1 \input texinfo @c -*-texinfo-*-
2 @c Copyright 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998,
3 @c 1999, 2000, 2001, 2002, 2003, 2004, 2005
4 @c Free Software Foundation, Inc.
7 @c makeinfo ignores cmds prev to setfilename, so its arg cannot make use
8 @c of @set vars. However, you can override filename with makeinfo -o.
13 @settitle Debugging with @value{GDBN}
14 @setchapternewpage odd
25 @c readline appendices use @vindex, @findex and @ftable,
26 @c annotate.texi and gdbmi use @findex.
30 @c !!set GDB manual's edition---not the same as GDB version!
31 @c This is updated by GNU Press.
34 @c !!set GDB edit command default editor
37 @c THIS MANUAL REQUIRES TEXINFO 4.0 OR LATER.
39 @c This is a dir.info fragment to support semi-automated addition of
40 @c manuals to an info tree.
41 @dircategory Software development
43 * Gdb: (gdb). The GNU debugger.
47 This file documents the @sc{gnu} debugger @value{GDBN}.
50 This is the @value{EDITION} Edition, of @cite{Debugging with
51 @value{GDBN}: the @sc{gnu} Source-Level Debugger} for @value{GDBN}
52 Version @value{GDBVN}.
54 Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998,@*
55 1999, 2000, 2001, 2002, 2003, 2004, 2005@*
56 Free Software Foundation, Inc.
58 Permission is granted to copy, distribute and/or modify this document
59 under the terms of the GNU Free Documentation License, Version 1.1 or
60 any later version published by the Free Software Foundation; with the
61 Invariant Sections being ``Free Software'' and ``Free Software Needs
62 Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,''
63 and with the Back-Cover Texts as in (a) below.
65 (a) The Free Software Foundation's Back-Cover Text is: ``You have
66 freedom to copy and modify this GNU Manual, like GNU software. Copies
67 published by the Free Software Foundation raise funds for GNU
72 @title Debugging with @value{GDBN}
73 @subtitle The @sc{gnu} Source-Level Debugger
75 @subtitle @value{EDITION} Edition, for @value{GDBN} version @value{GDBVN}
76 @author Richard Stallman, Roland Pesch, Stan Shebs, et al.
80 \hfill (Send bugs and comments on @value{GDBN} to bug-gdb\@gnu.org.)\par
81 \hfill {\it Debugging with @value{GDBN}}\par
82 \hfill \TeX{}info \texinfoversion\par
86 @vskip 0pt plus 1filll
87 Copyright @copyright{} 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
88 1996, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
89 Free Software Foundation, Inc.
91 Published by the Free Software Foundation @*
92 59 Temple Place - Suite 330, @*
93 Boston, MA 02111-1307 USA @*
96 Permission is granted to copy, distribute and/or modify this document
97 under the terms of the GNU Free Documentation License, Version 1.1 or
98 any later version published by the Free Software Foundation; with the
99 Invariant Sections being ``Free Software'' and ``Free Software Needs
100 Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,''
101 and with the Back-Cover Texts as in (a) below.
103 (a) The Free Software Foundation's Back-Cover Text is: ``You have
104 freedom to copy and modify this GNU Manual, like GNU software. Copies
105 published by the Free Software Foundation raise funds for GNU
111 @node Top, Summary, (dir), (dir)
113 @top Debugging with @value{GDBN}
115 This file describes @value{GDBN}, the @sc{gnu} symbolic debugger.
117 This is the @value{EDITION} Edition, for @value{GDBN} Version
120 Copyright (C) 1988-2005 Free Software Foundation, Inc.
123 * Summary:: Summary of @value{GDBN}
124 * Sample Session:: A sample @value{GDBN} session
126 * Invocation:: Getting in and out of @value{GDBN}
127 * Commands:: @value{GDBN} commands
128 * Running:: Running programs under @value{GDBN}
129 * Stopping:: Stopping and continuing
130 * Stack:: Examining the stack
131 * Source:: Examining source files
132 * Data:: Examining data
133 * Macros:: Preprocessor Macros
134 * Tracepoints:: Debugging remote targets non-intrusively
135 * Overlays:: Debugging programs that use overlays
137 * Languages:: Using @value{GDBN} with different languages
139 * Symbols:: Examining the symbol table
140 * Altering:: Altering execution
141 * GDB Files:: @value{GDBN} files
142 * Targets:: Specifying a debugging target
143 * Remote Debugging:: Debugging remote programs
144 * Configurations:: Configuration-specific information
145 * Controlling GDB:: Controlling @value{GDBN}
146 * Sequences:: Canned sequences of commands
147 * TUI:: @value{GDBN} Text User Interface
148 * Interpreters:: Command Interpreters
149 * Emacs:: Using @value{GDBN} under @sc{gnu} Emacs
150 * Annotations:: @value{GDBN}'s annotation interface.
151 * GDB/MI:: @value{GDBN}'s Machine Interface.
153 * GDB Bugs:: Reporting bugs in @value{GDBN}
154 * Formatting Documentation:: How to format and print @value{GDBN} documentation
156 * Command Line Editing:: Command Line Editing
157 * Using History Interactively:: Using History Interactively
158 * Installing GDB:: Installing GDB
159 * Maintenance Commands:: Maintenance Commands
160 * Remote Protocol:: GDB Remote Serial Protocol
161 * Agent Expressions:: The GDB Agent Expression Mechanism
162 * Copying:: GNU General Public License says
163 how you can copy and share GDB
164 * GNU Free Documentation License:: The license for this documentation
173 @unnumbered Summary of @value{GDBN}
175 The purpose of a debugger such as @value{GDBN} is to allow you to see what is
176 going on ``inside'' another program while it executes---or what another
177 program was doing at the moment it crashed.
179 @value{GDBN} can do four main kinds of things (plus other things in support of
180 these) to help you catch bugs in the act:
184 Start your program, specifying anything that might affect its behavior.
187 Make your program stop on specified conditions.
190 Examine what has happened, when your program has stopped.
193 Change things in your program, so you can experiment with correcting the
194 effects of one bug and go on to learn about another.
197 You can use @value{GDBN} to debug programs written in C and C@t{++}.
198 For more information, see @ref{Supported languages,,Supported languages}.
199 For more information, see @ref{C,,C and C++}.
202 Support for Modula-2 is partial. For information on Modula-2, see
203 @ref{Modula-2,,Modula-2}.
206 Debugging Pascal programs which use sets, subranges, file variables, or
207 nested functions does not currently work. @value{GDBN} does not support
208 entering expressions, printing values, or similar features using Pascal
212 @value{GDBN} can be used to debug programs written in Fortran, although
213 it may be necessary to refer to some variables with a trailing
216 @value{GDBN} can be used to debug programs written in Objective-C,
217 using either the Apple/NeXT or the GNU Objective-C runtime.
220 * Free Software:: Freely redistributable software
221 * Contributors:: Contributors to GDB
225 @unnumberedsec Free software
227 @value{GDBN} is @dfn{free software}, protected by the @sc{gnu}
228 General Public License
229 (GPL). The GPL gives you the freedom to copy or adapt a licensed
230 program---but every person getting a copy also gets with it the
231 freedom to modify that copy (which means that they must get access to
232 the source code), and the freedom to distribute further copies.
233 Typical software companies use copyrights to limit your freedoms; the
234 Free Software Foundation uses the GPL to preserve these freedoms.
236 Fundamentally, the General Public License is a license which says that
237 you have these freedoms and that you cannot take these freedoms away
240 @unnumberedsec Free Software Needs Free Documentation
242 The biggest deficiency in the free software community today is not in
243 the software---it is the lack of good free documentation that we can
244 include with the free software. Many of our most important
245 programs do not come with free reference manuals and free introductory
246 texts. Documentation is an essential part of any software package;
247 when an important free software package does not come with a free
248 manual and a free tutorial, that is a major gap. We have many such
251 Consider Perl, for instance. The tutorial manuals that people
252 normally use are non-free. How did this come about? Because the
253 authors of those manuals published them with restrictive terms---no
254 copying, no modification, source files not available---which exclude
255 them from the free software world.
257 That wasn't the first time this sort of thing happened, and it was far
258 from the last. Many times we have heard a GNU user eagerly describe a
259 manual that he is writing, his intended contribution to the community,
260 only to learn that he had ruined everything by signing a publication
261 contract to make it non-free.
263 Free documentation, like free software, is a matter of freedom, not
264 price. The problem with the non-free manual is not that publishers
265 charge a price for printed copies---that in itself is fine. (The Free
266 Software Foundation sells printed copies of manuals, too.) The
267 problem is the restrictions on the use of the manual. Free manuals
268 are available in source code form, and give you permission to copy and
269 modify. Non-free manuals do not allow this.
271 The criteria of freedom for a free manual are roughly the same as for
272 free software. Redistribution (including the normal kinds of
273 commercial redistribution) must be permitted, so that the manual can
274 accompany every copy of the program, both on-line and on paper.
276 Permission for modification of the technical content is crucial too.
277 When people modify the software, adding or changing features, if they
278 are conscientious they will change the manual too---so they can
279 provide accurate and clear documentation for the modified program. A
280 manual that leaves you no choice but to write a new manual to document
281 a changed version of the program is not really available to our
284 Some kinds of limits on the way modification is handled are
285 acceptable. For example, requirements to preserve the original
286 author's copyright notice, the distribution terms, or the list of
287 authors, are ok. It is also no problem to require modified versions
288 to include notice that they were modified. Even entire sections that
289 may not be deleted or changed are acceptable, as long as they deal
290 with nontechnical topics (like this one). These kinds of restrictions
291 are acceptable because they don't obstruct the community's normal use
294 However, it must be possible to modify all the @emph{technical}
295 content of the manual, and then distribute the result in all the usual
296 media, through all the usual channels. Otherwise, the restrictions
297 obstruct the use of the manual, it is not free, and we need another
298 manual to replace it.
300 Please spread the word about this issue. Our community continues to
301 lose manuals to proprietary publishing. If we spread the word that
302 free software needs free reference manuals and free tutorials, perhaps
303 the next person who wants to contribute by writing documentation will
304 realize, before it is too late, that only free manuals contribute to
305 the free software community.
307 If you are writing documentation, please insist on publishing it under
308 the GNU Free Documentation License or another free documentation
309 license. Remember that this decision requires your approval---you
310 don't have to let the publisher decide. Some commercial publishers
311 will use a free license if you insist, but they will not propose the
312 option; it is up to you to raise the issue and say firmly that this is
313 what you want. If the publisher you are dealing with refuses, please
314 try other publishers. If you're not sure whether a proposed license
315 is free, write to @email{licensing@@gnu.org}.
317 You can encourage commercial publishers to sell more free, copylefted
318 manuals and tutorials by buying them, and particularly by buying
319 copies from the publishers that paid for their writing or for major
320 improvements. Meanwhile, try to avoid buying non-free documentation
321 at all. Check the distribution terms of a manual before you buy it,
322 and insist that whoever seeks your business must respect your freedom.
323 Check the history of the book, and try to reward the publishers that
324 have paid or pay the authors to work on it.
326 The Free Software Foundation maintains a list of free documentation
327 published by other publishers, at
328 @url{http://www.fsf.org/doc/other-free-books.html}.
331 @unnumberedsec Contributors to @value{GDBN}
333 Richard Stallman was the original author of @value{GDBN}, and of many
334 other @sc{gnu} programs. Many others have contributed to its
335 development. This section attempts to credit major contributors. One
336 of the virtues of free software is that everyone is free to contribute
337 to it; with regret, we cannot actually acknowledge everyone here. The
338 file @file{ChangeLog} in the @value{GDBN} distribution approximates a
339 blow-by-blow account.
341 Changes much prior to version 2.0 are lost in the mists of time.
344 @emph{Plea:} Additions to this section are particularly welcome. If you
345 or your friends (or enemies, to be evenhanded) have been unfairly
346 omitted from this list, we would like to add your names!
349 So that they may not regard their many labors as thankless, we
350 particularly thank those who shepherded @value{GDBN} through major
352 Andrew Cagney (releases 6.1, 6.0, 5.3, 5.2, 5.1 and 5.0);
353 Jim Blandy (release 4.18);
354 Jason Molenda (release 4.17);
355 Stan Shebs (release 4.14);
356 Fred Fish (releases 4.16, 4.15, 4.13, 4.12, 4.11, 4.10, and 4.9);
357 Stu Grossman and John Gilmore (releases 4.8, 4.7, 4.6, 4.5, and 4.4);
358 John Gilmore (releases 4.3, 4.2, 4.1, 4.0, and 3.9);
359 Jim Kingdon (releases 3.5, 3.4, and 3.3);
360 and Randy Smith (releases 3.2, 3.1, and 3.0).
362 Richard Stallman, assisted at various times by Peter TerMaat, Chris
363 Hanson, and Richard Mlynarik, handled releases through 2.8.
365 Michael Tiemann is the author of most of the @sc{gnu} C@t{++} support
366 in @value{GDBN}, with significant additional contributions from Per
367 Bothner and Daniel Berlin. James Clark wrote the @sc{gnu} C@t{++}
368 demangler. Early work on C@t{++} was by Peter TerMaat (who also did
369 much general update work leading to release 3.0).
371 @value{GDBN} uses the BFD subroutine library to examine multiple
372 object-file formats; BFD was a joint project of David V.
373 Henkel-Wallace, Rich Pixley, Steve Chamberlain, and John Gilmore.
375 David Johnson wrote the original COFF support; Pace Willison did
376 the original support for encapsulated COFF.
378 Brent Benson of Harris Computer Systems contributed DWARF 2 support.
380 Adam de Boor and Bradley Davis contributed the ISI Optimum V support.
381 Per Bothner, Noboyuki Hikichi, and Alessandro Forin contributed MIPS
383 Jean-Daniel Fekete contributed Sun 386i support.
384 Chris Hanson improved the HP9000 support.
385 Noboyuki Hikichi and Tomoyuki Hasei contributed Sony/News OS 3 support.
386 David Johnson contributed Encore Umax support.
387 Jyrki Kuoppala contributed Altos 3068 support.
388 Jeff Law contributed HP PA and SOM support.
389 Keith Packard contributed NS32K support.
390 Doug Rabson contributed Acorn Risc Machine support.
391 Bob Rusk contributed Harris Nighthawk CX-UX support.
392 Chris Smith contributed Convex support (and Fortran debugging).
393 Jonathan Stone contributed Pyramid support.
394 Michael Tiemann contributed SPARC support.
395 Tim Tucker contributed support for the Gould NP1 and Gould Powernode.
396 Pace Willison contributed Intel 386 support.
397 Jay Vosburgh contributed Symmetry support.
398 Marko Mlinar contributed OpenRISC 1000 support.
400 Andreas Schwab contributed M68K @sc{gnu}/Linux support.
402 Rich Schaefer and Peter Schauer helped with support of SunOS shared
405 Jay Fenlason and Roland McGrath ensured that @value{GDBN} and GAS agree
406 about several machine instruction sets.
408 Patrick Duval, Ted Goldstein, Vikram Koka and Glenn Engel helped develop
409 remote debugging. Intel Corporation, Wind River Systems, AMD, and ARM
410 contributed remote debugging modules for the i960, VxWorks, A29K UDI,
411 and RDI targets, respectively.
413 Brian Fox is the author of the readline libraries providing
414 command-line editing and command history.
416 Andrew Beers of SUNY Buffalo wrote the language-switching code, the
417 Modula-2 support, and contributed the Languages chapter of this manual.
419 Fred Fish wrote most of the support for Unix System Vr4.
420 He also enhanced the command-completion support to cover C@t{++} overloaded
423 Hitachi America (now Renesas America), Ltd. sponsored the support for
424 H8/300, H8/500, and Super-H processors.
426 NEC sponsored the support for the v850, Vr4xxx, and Vr5xxx processors.
428 Mitsubishi (now Renesas) sponsored the support for D10V, D30V, and M32R/D
431 Toshiba sponsored the support for the TX39 Mips processor.
433 Matsushita sponsored the support for the MN10200 and MN10300 processors.
435 Fujitsu sponsored the support for SPARClite and FR30 processors.
437 Kung Hsu, Jeff Law, and Rick Sladkey added support for hardware
440 Michael Snyder added support for tracepoints.
442 Stu Grossman wrote gdbserver.
444 Jim Kingdon, Peter Schauer, Ian Taylor, and Stu Grossman made
445 nearly innumerable bug fixes and cleanups throughout @value{GDBN}.
447 The following people at the Hewlett-Packard Company contributed
448 support for the PA-RISC 2.0 architecture, HP-UX 10.20, 10.30, and 11.0
449 (narrow mode), HP's implementation of kernel threads, HP's aC@t{++}
450 compiler, and the Text User Interface (nee Terminal User Interface):
451 Ben Krepp, Richard Title, John Bishop, Susan Macchia, Kathy Mann,
452 Satish Pai, India Paul, Steve Rehrauer, and Elena Zannoni. Kim Haase
453 provided HP-specific information in this manual.
455 DJ Delorie ported @value{GDBN} to MS-DOS, for the DJGPP project.
456 Robert Hoehne made significant contributions to the DJGPP port.
458 Cygnus Solutions has sponsored @value{GDBN} maintenance and much of its
459 development since 1991. Cygnus engineers who have worked on @value{GDBN}
460 fulltime include Mark Alexander, Jim Blandy, Per Bothner, Kevin
461 Buettner, Edith Epstein, Chris Faylor, Fred Fish, Martin Hunt, Jim
462 Ingham, John Gilmore, Stu Grossman, Kung Hsu, Jim Kingdon, John Metzler,
463 Fernando Nasser, Geoffrey Noer, Dawn Perchik, Rich Pixley, Zdenek
464 Radouch, Keith Seitz, Stan Shebs, David Taylor, and Elena Zannoni. In
465 addition, Dave Brolley, Ian Carmichael, Steve Chamberlain, Nick Clifton,
466 JT Conklin, Stan Cox, DJ Delorie, Ulrich Drepper, Frank Eigler, Doug
467 Evans, Sean Fagan, David Henkel-Wallace, Richard Henderson, Jeff
468 Holcomb, Jeff Law, Jim Lemke, Tom Lord, Bob Manson, Michael Meissner,
469 Jason Merrill, Catherine Moore, Drew Moseley, Ken Raeburn, Gavin
470 Romig-Koch, Rob Savoye, Jamie Smith, Mike Stump, Ian Taylor, Angela
471 Thomas, Michael Tiemann, Tom Tromey, Ron Unrau, Jim Wilson, and David
472 Zuhn have made contributions both large and small.
474 Andrew Cagney, Fernando Nasser, and Elena Zannoni, while working for
475 Cygnus Solutions, implemented the original @sc{gdb/mi} interface.
477 Jim Blandy added support for preprocessor macros, while working for Red
480 Andrew Cagney designed @value{GDBN}'s architecture vector. Many
481 people including Andrew Cagney, Stephane Carrez, Randolph Chung, Nick
482 Duffek, Richard Henderson, Mark Kettenis, Grace Sainsbury, Kei
483 Sakamoto, Yoshinori Sato, Michael Snyder, Andreas Schwab, Jason
484 Thorpe, Corinna Vinschen, Ulrich Weigand, and Elena Zannoni, helped
485 with the migration of old architectures to this new framework.
488 @chapter A Sample @value{GDBN} Session
490 You can use this manual at your leisure to read all about @value{GDBN}.
491 However, a handful of commands are enough to get started using the
492 debugger. This chapter illustrates those commands.
495 In this sample session, we emphasize user input like this: @b{input},
496 to make it easier to pick out from the surrounding output.
499 @c FIXME: this example may not be appropriate for some configs, where
500 @c FIXME...primary interest is in remote use.
502 One of the preliminary versions of @sc{gnu} @code{m4} (a generic macro
503 processor) exhibits the following bug: sometimes, when we change its
504 quote strings from the default, the commands used to capture one macro
505 definition within another stop working. In the following short @code{m4}
506 session, we define a macro @code{foo} which expands to @code{0000}; we
507 then use the @code{m4} built-in @code{defn} to define @code{bar} as the
508 same thing. However, when we change the open quote string to
509 @code{<QUOTE>} and the close quote string to @code{<UNQUOTE>}, the same
510 procedure fails to define a new synonym @code{baz}:
519 @b{define(bar,defn(`foo'))}
523 @b{changequote(<QUOTE>,<UNQUOTE>)}
525 @b{define(baz,defn(<QUOTE>foo<UNQUOTE>))}
528 m4: End of input: 0: fatal error: EOF in string
532 Let us use @value{GDBN} to try to see what is going on.
535 $ @b{@value{GDBP} m4}
536 @c FIXME: this falsifies the exact text played out, to permit smallbook
537 @c FIXME... format to come out better.
538 @value{GDBN} is free software and you are welcome to distribute copies
539 of it under certain conditions; type "show copying" to see
541 There is absolutely no warranty for @value{GDBN}; type "show warranty"
544 @value{GDBN} @value{GDBVN}, Copyright 1999 Free Software Foundation, Inc...
549 @value{GDBN} reads only enough symbol data to know where to find the
550 rest when needed; as a result, the first prompt comes up very quickly.
551 We now tell @value{GDBN} to use a narrower display width than usual, so
552 that examples fit in this manual.
555 (@value{GDBP}) @b{set width 70}
559 We need to see how the @code{m4} built-in @code{changequote} works.
560 Having looked at the source, we know the relevant subroutine is
561 @code{m4_changequote}, so we set a breakpoint there with the @value{GDBN}
562 @code{break} command.
565 (@value{GDBP}) @b{break m4_changequote}
566 Breakpoint 1 at 0x62f4: file builtin.c, line 879.
570 Using the @code{run} command, we start @code{m4} running under @value{GDBN}
571 control; as long as control does not reach the @code{m4_changequote}
572 subroutine, the program runs as usual:
575 (@value{GDBP}) @b{run}
576 Starting program: /work/Editorial/gdb/gnu/m4/m4
584 To trigger the breakpoint, we call @code{changequote}. @value{GDBN}
585 suspends execution of @code{m4}, displaying information about the
586 context where it stops.
589 @b{changequote(<QUOTE>,<UNQUOTE>)}
591 Breakpoint 1, m4_changequote (argc=3, argv=0x33c70)
593 879 if (bad_argc(TOKEN_DATA_TEXT(argv[0]),argc,1,3))
597 Now we use the command @code{n} (@code{next}) to advance execution to
598 the next line of the current function.
602 882 set_quotes((argc >= 2) ? TOKEN_DATA_TEXT(argv[1])\
607 @code{set_quotes} looks like a promising subroutine. We can go into it
608 by using the command @code{s} (@code{step}) instead of @code{next}.
609 @code{step} goes to the next line to be executed in @emph{any}
610 subroutine, so it steps into @code{set_quotes}.
614 set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>")
616 530 if (lquote != def_lquote)
620 The display that shows the subroutine where @code{m4} is now
621 suspended (and its arguments) is called a stack frame display. It
622 shows a summary of the stack. We can use the @code{backtrace}
623 command (which can also be spelled @code{bt}), to see where we are
624 in the stack as a whole: the @code{backtrace} command displays a
625 stack frame for each active subroutine.
628 (@value{GDBP}) @b{bt}
629 #0 set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>")
631 #1 0x6344 in m4_changequote (argc=3, argv=0x33c70)
633 #2 0x8174 in expand_macro (sym=0x33320) at macro.c:242
634 #3 0x7a88 in expand_token (obs=0x0, t=209696, td=0xf7fffa30)
636 #4 0x79dc in expand_input () at macro.c:40
637 #5 0x2930 in main (argc=0, argv=0xf7fffb20) at m4.c:195
641 We step through a few more lines to see what happens. The first two
642 times, we can use @samp{s}; the next two times we use @code{n} to avoid
643 falling into the @code{xstrdup} subroutine.
647 0x3b5c 532 if (rquote != def_rquote)
649 0x3b80 535 lquote = (lq == nil || *lq == '\0') ? \
650 def_lquote : xstrdup(lq);
652 536 rquote = (rq == nil || *rq == '\0') ? def_rquote\
655 538 len_lquote = strlen(rquote);
659 The last line displayed looks a little odd; we can examine the variables
660 @code{lquote} and @code{rquote} to see if they are in fact the new left
661 and right quotes we specified. We use the command @code{p}
662 (@code{print}) to see their values.
665 (@value{GDBP}) @b{p lquote}
666 $1 = 0x35d40 "<QUOTE>"
667 (@value{GDBP}) @b{p rquote}
668 $2 = 0x35d50 "<UNQUOTE>"
672 @code{lquote} and @code{rquote} are indeed the new left and right quotes.
673 To look at some context, we can display ten lines of source
674 surrounding the current line with the @code{l} (@code{list}) command.
680 535 lquote = (lq == nil || *lq == '\0') ? def_lquote\
682 536 rquote = (rq == nil || *rq == '\0') ? def_rquote\
685 538 len_lquote = strlen(rquote);
686 539 len_rquote = strlen(lquote);
693 Let us step past the two lines that set @code{len_lquote} and
694 @code{len_rquote}, and then examine the values of those variables.
698 539 len_rquote = strlen(lquote);
701 (@value{GDBP}) @b{p len_lquote}
703 (@value{GDBP}) @b{p len_rquote}
708 That certainly looks wrong, assuming @code{len_lquote} and
709 @code{len_rquote} are meant to be the lengths of @code{lquote} and
710 @code{rquote} respectively. We can set them to better values using
711 the @code{p} command, since it can print the value of
712 any expression---and that expression can include subroutine calls and
716 (@value{GDBP}) @b{p len_lquote=strlen(lquote)}
718 (@value{GDBP}) @b{p len_rquote=strlen(rquote)}
723 Is that enough to fix the problem of using the new quotes with the
724 @code{m4} built-in @code{defn}? We can allow @code{m4} to continue
725 executing with the @code{c} (@code{continue}) command, and then try the
726 example that caused trouble initially:
732 @b{define(baz,defn(<QUOTE>foo<UNQUOTE>))}
739 Success! The new quotes now work just as well as the default ones. The
740 problem seems to have been just the two typos defining the wrong
741 lengths. We allow @code{m4} exit by giving it an EOF as input:
745 Program exited normally.
749 The message @samp{Program exited normally.} is from @value{GDBN}; it
750 indicates @code{m4} has finished executing. We can end our @value{GDBN}
751 session with the @value{GDBN} @code{quit} command.
754 (@value{GDBP}) @b{quit}
758 @chapter Getting In and Out of @value{GDBN}
760 This chapter discusses how to start @value{GDBN}, and how to get out of it.
764 type @samp{@value{GDBP}} to start @value{GDBN}.
766 type @kbd{quit} or @kbd{C-d} to exit.
770 * Invoking GDB:: How to start @value{GDBN}
771 * Quitting GDB:: How to quit @value{GDBN}
772 * Shell Commands:: How to use shell commands inside @value{GDBN}
773 * Logging output:: How to log @value{GDBN}'s output to a file
777 @section Invoking @value{GDBN}
779 Invoke @value{GDBN} by running the program @code{@value{GDBP}}. Once started,
780 @value{GDBN} reads commands from the terminal until you tell it to exit.
782 You can also run @code{@value{GDBP}} with a variety of arguments and options,
783 to specify more of your debugging environment at the outset.
785 The command-line options described here are designed
786 to cover a variety of situations; in some environments, some of these
787 options may effectively be unavailable.
789 The most usual way to start @value{GDBN} is with one argument,
790 specifying an executable program:
793 @value{GDBP} @var{program}
797 You can also start with both an executable program and a core file
801 @value{GDBP} @var{program} @var{core}
804 You can, instead, specify a process ID as a second argument, if you want
805 to debug a running process:
808 @value{GDBP} @var{program} 1234
812 would attach @value{GDBN} to process @code{1234} (unless you also have a file
813 named @file{1234}; @value{GDBN} does check for a core file first).
815 Taking advantage of the second command-line argument requires a fairly
816 complete operating system; when you use @value{GDBN} as a remote
817 debugger attached to a bare board, there may not be any notion of
818 ``process'', and there is often no way to get a core dump. @value{GDBN}
819 will warn you if it is unable to attach or to read core dumps.
821 You can optionally have @code{@value{GDBP}} pass any arguments after the
822 executable file to the inferior using @code{--args}. This option stops
825 gdb --args gcc -O2 -c foo.c
827 This will cause @code{@value{GDBP}} to debug @code{gcc}, and to set
828 @code{gcc}'s command-line arguments (@pxref{Arguments}) to @samp{-O2 -c foo.c}.
830 You can run @code{@value{GDBP}} without printing the front material, which describes
831 @value{GDBN}'s non-warranty, by specifying @code{-silent}:
838 You can further control how @value{GDBN} starts up by using command-line
839 options. @value{GDBN} itself can remind you of the options available.
849 to display all available options and briefly describe their use
850 (@samp{@value{GDBP} -h} is a shorter equivalent).
852 All options and command line arguments you give are processed
853 in sequential order. The order makes a difference when the
854 @samp{-x} option is used.
858 * File Options:: Choosing files
859 * Mode Options:: Choosing modes
860 * Startup:: What @value{GDBN} does during startup
864 @subsection Choosing files
866 When @value{GDBN} starts, it reads any arguments other than options as
867 specifying an executable file and core file (or process ID). This is
868 the same as if the arguments were specified by the @samp{-se} and
869 @samp{-c} (or @samp{-p} options respectively. (@value{GDBN} reads the
870 first argument that does not have an associated option flag as
871 equivalent to the @samp{-se} option followed by that argument; and the
872 second argument that does not have an associated option flag, if any, as
873 equivalent to the @samp{-c}/@samp{-p} option followed by that argument.)
874 If the second argument begins with a decimal digit, @value{GDBN} will
875 first attempt to attach to it as a process, and if that fails, attempt
876 to open it as a corefile. If you have a corefile whose name begins with
877 a digit, you can prevent @value{GDBN} from treating it as a pid by
878 prefixing it with @file{./}, eg. @file{./12345}.
880 If @value{GDBN} has not been configured to included core file support,
881 such as for most embedded targets, then it will complain about a second
882 argument and ignore it.
884 Many options have both long and short forms; both are shown in the
885 following list. @value{GDBN} also recognizes the long forms if you truncate
886 them, so long as enough of the option is present to be unambiguous.
887 (If you prefer, you can flag option arguments with @samp{--} rather
888 than @samp{-}, though we illustrate the more usual convention.)
890 @c NOTE: the @cindex entries here use double dashes ON PURPOSE. This
891 @c way, both those who look for -foo and --foo in the index, will find
895 @item -symbols @var{file}
897 @cindex @code{--symbols}
899 Read symbol table from file @var{file}.
901 @item -exec @var{file}
903 @cindex @code{--exec}
905 Use file @var{file} as the executable file to execute when appropriate,
906 and for examining pure data in conjunction with a core dump.
910 Read symbol table from file @var{file} and use it as the executable
913 @item -core @var{file}
915 @cindex @code{--core}
917 Use file @var{file} as a core dump to examine.
919 @item -c @var{number}
920 @item -pid @var{number}
921 @itemx -p @var{number}
924 Connect to process ID @var{number}, as with the @code{attach} command.
925 If there is no such process, @value{GDBN} will attempt to open a core
926 file named @var{number}.
928 @item -command @var{file}
930 @cindex @code{--command}
932 Execute @value{GDBN} commands from file @var{file}. @xref{Command
933 Files,, Command files}.
935 @item -directory @var{directory}
936 @itemx -d @var{directory}
937 @cindex @code{--directory}
939 Add @var{directory} to the path to search for source files.
943 @cindex @code{--mapped}
945 @emph{Warning: this option depends on operating system facilities that are not
946 supported on all systems.}@*
947 If memory-mapped files are available on your system through the @code{mmap}
948 system call, you can use this option
949 to have @value{GDBN} write the symbols from your
950 program into a reusable file in the current directory. If the program you are debugging is
951 called @file{/tmp/fred}, the mapped symbol file is @file{/tmp/fred.syms}.
952 Future @value{GDBN} debugging sessions notice the presence of this file,
953 and can quickly map in symbol information from it, rather than reading
954 the symbol table from the executable program.
956 The @file{.syms} file is specific to the host machine where @value{GDBN}
957 is run. It holds an exact image of the internal @value{GDBN} symbol
958 table. It cannot be shared across multiple host platforms.
962 @cindex @code{--readnow}
964 Read each symbol file's entire symbol table immediately, rather than
965 the default, which is to read it incrementally as it is needed.
966 This makes startup slower, but makes future operations faster.
970 You typically combine the @code{-mapped} and @code{-readnow} options in
971 order to build a @file{.syms} file that contains complete symbol
972 information. (@xref{Files,,Commands to specify files}, for information
973 on @file{.syms} files.) A simple @value{GDBN} invocation to do nothing
974 but build a @file{.syms} file for future use is:
977 gdb -batch -nx -mapped -readnow programname
981 @subsection Choosing modes
983 You can run @value{GDBN} in various alternative modes---for example, in
984 batch mode or quiet mode.
991 Do not execute commands found in any initialization files. Normally,
992 @value{GDBN} executes the commands in these files after all the command
993 options and arguments have been processed. @xref{Command Files,,Command
999 @cindex @code{--quiet}
1000 @cindex @code{--silent}
1002 ``Quiet''. Do not print the introductory and copyright messages. These
1003 messages are also suppressed in batch mode.
1006 @cindex @code{--batch}
1007 Run in batch mode. Exit with status @code{0} after processing all the
1008 command files specified with @samp{-x} (and all commands from
1009 initialization files, if not inhibited with @samp{-n}). Exit with
1010 nonzero status if an error occurs in executing the @value{GDBN} commands
1011 in the command files.
1013 Batch mode may be useful for running @value{GDBN} as a filter, for
1014 example to download and run a program on another computer; in order to
1015 make this more useful, the message
1018 Program exited normally.
1022 (which is ordinarily issued whenever a program running under
1023 @value{GDBN} control terminates) is not issued when running in batch
1028 @cindex @code{--nowindows}
1030 ``No windows''. If @value{GDBN} comes with a graphical user interface
1031 (GUI) built in, then this option tells @value{GDBN} to only use the command-line
1032 interface. If no GUI is available, this option has no effect.
1036 @cindex @code{--windows}
1038 If @value{GDBN} includes a GUI, then this option requires it to be
1041 @item -cd @var{directory}
1043 Run @value{GDBN} using @var{directory} as its working directory,
1044 instead of the current directory.
1048 @cindex @code{--fullname}
1050 @sc{gnu} Emacs sets this option when it runs @value{GDBN} as a
1051 subprocess. It tells @value{GDBN} to output the full file name and line
1052 number in a standard, recognizable fashion each time a stack frame is
1053 displayed (which includes each time your program stops). This
1054 recognizable format looks like two @samp{\032} characters, followed by
1055 the file name, line number and character position separated by colons,
1056 and a newline. The Emacs-to-@value{GDBN} interface program uses the two
1057 @samp{\032} characters as a signal to display the source code for the
1061 @cindex @code{--epoch}
1062 The Epoch Emacs-@value{GDBN} interface sets this option when it runs
1063 @value{GDBN} as a subprocess. It tells @value{GDBN} to modify its print
1064 routines so as to allow Epoch to display values of expressions in a
1067 @item -annotate @var{level}
1068 @cindex @code{--annotate}
1069 This option sets the @dfn{annotation level} inside @value{GDBN}. Its
1070 effect is identical to using @samp{set annotate @var{level}}
1071 (@pxref{Annotations}). The annotation @var{level} controls how much
1072 information @value{GDBN} prints together with its prompt, values of
1073 expressions, source lines, and other types of output. Level 0 is the
1074 normal, level 1 is for use when @value{GDBN} is run as a subprocess of
1075 @sc{gnu} Emacs, level 3 is the maximum annotation suitable for programs
1076 that control @value{GDBN}, and level 2 has been deprecated.
1078 The annotation mechanism has largely been superseded by @sc{gdb/mi}
1082 @cindex @code{--args}
1083 Change interpretation of command line so that arguments following the
1084 executable file are passed as command line arguments to the inferior.
1085 This option stops option processing.
1087 @item -baud @var{bps}
1089 @cindex @code{--baud}
1091 Set the line speed (baud rate or bits per second) of any serial
1092 interface used by @value{GDBN} for remote debugging.
1094 @item -l @var{timeout}
1096 Set the timeout (in seconds) of any communication used by @value{GDBN}
1097 for remote debugging.
1099 @item -tty @var{device}
1100 @itemx -t @var{device}
1101 @cindex @code{--tty}
1103 Run using @var{device} for your program's standard input and output.
1104 @c FIXME: kingdon thinks there is more to -tty. Investigate.
1106 @c resolve the situation of these eventually
1108 @cindex @code{--tui}
1109 Activate the @dfn{Text User Interface} when starting. The Text User
1110 Interface manages several text windows on the terminal, showing
1111 source, assembly, registers and @value{GDBN} command outputs
1112 (@pxref{TUI, ,@value{GDBN} Text User Interface}). Alternatively, the
1113 Text User Interface can be enabled by invoking the program
1114 @samp{gdbtui}. Do not use this option if you run @value{GDBN} from
1115 Emacs (@pxref{Emacs, ,Using @value{GDBN} under @sc{gnu} Emacs}).
1118 @c @cindex @code{--xdb}
1119 @c Run in XDB compatibility mode, allowing the use of certain XDB commands.
1120 @c For information, see the file @file{xdb_trans.html}, which is usually
1121 @c installed in the directory @code{/opt/langtools/wdb/doc} on HP-UX
1124 @item -interpreter @var{interp}
1125 @cindex @code{--interpreter}
1126 Use the interpreter @var{interp} for interface with the controlling
1127 program or device. This option is meant to be set by programs which
1128 communicate with @value{GDBN} using it as a back end.
1129 @xref{Interpreters, , Command Interpreters}.
1131 @samp{--interpreter=mi} (or @samp{--interpreter=mi2}) causes
1132 @value{GDBN} to use the @dfn{@sc{gdb/mi} interface} (@pxref{GDB/MI, ,
1133 The @sc{gdb/mi} Interface}) included since @value{GDBN} version 6.0. The
1134 previous @sc{gdb/mi} interface, included in @value{GDBN} version 5.3 and
1135 selected with @samp{--interpreter=mi1}, is deprecated. Earlier
1136 @sc{gdb/mi} interfaces are no longer supported.
1139 @cindex @code{--write}
1140 Open the executable and core files for both reading and writing. This
1141 is equivalent to the @samp{set write on} command inside @value{GDBN}
1145 @cindex @code{--statistics}
1146 This option causes @value{GDBN} to print statistics about time and
1147 memory usage after it completes each command and returns to the prompt.
1150 @cindex @code{--version}
1151 This option causes @value{GDBN} to print its version number and
1152 no-warranty blurb, and exit.
1157 @subsection What @value{GDBN} does during startup
1158 @cindex @value{GDBN} startup
1160 Here's the description of what @value{GDBN} does during session startup:
1164 Sets up the command interpreter as specified by the command line
1165 (@pxref{Mode Options, interpreter}).
1169 Reads the @dfn{init file} (if any) in your home directory@footnote{On
1170 DOS/Windows systems, the home directory is the one pointed to by the
1171 @code{HOME} environment variable.} and executes all the commands in
1175 Processes command line options and operands.
1178 Reads and executes the commands from init file (if any) in the current
1179 working directory. This is only done if the current directory is
1180 different from your home directory. Thus, you can have more than one
1181 init file, one generic in your home directory, and another, specific
1182 to the program you are debugging, in the directory where you invoke
1186 Reads command files specified by the @samp{-x} option. @xref{Command
1187 Files}, for more details about @value{GDBN} command files.
1190 Reads the command history recorded in the @dfn{history file}.
1191 @xref{Command History}, for more details about the command history and the
1192 files where @value{GDBN} records it.
1195 Init files use the same syntax as @dfn{command files} (@pxref{Command
1196 Files}) and are processed by @value{GDBN} in the same way. The init
1197 file in your home directory can set options (such as @samp{set
1198 complaints}) that affect subsequent processing of command line options
1199 and operands. Init files are not executed if you use the @samp{-nx}
1200 option (@pxref{Mode Options, ,Choosing modes}).
1202 @cindex init file name
1203 @cindex @file{.gdbinit}
1204 The @value{GDBN} init files are normally called @file{.gdbinit}.
1205 On some configurations of @value{GDBN}, the init file is known by a
1206 different name (these are typically environments where a specialized
1207 form of @value{GDBN} may need to coexist with other forms, hence a
1208 different name for the specialized version's init file). These are the
1209 environments with special init file names:
1212 @cindex @file{gdb.ini}
1214 The DJGPP port of @value{GDBN} uses the name @file{gdb.ini}, due to
1215 the limitations of file names imposed by DOS filesystems. The Windows
1216 ports of @value{GDBN} use the standard name, but if they find a
1217 @file{gdb.ini} file, they warn you about that and suggest to rename
1218 the file to the standard name.
1220 @cindex @file{.vxgdbinit}
1222 VxWorks (Wind River Systems real-time OS): @file{.vxgdbinit}
1224 @cindex @file{.os68gdbinit}
1226 OS68K (Enea Data Systems real-time OS): @file{.os68gdbinit}
1228 @cindex @file{.esgdbinit}
1230 ES-1800 (Ericsson Telecom AB M68000 emulator): @file{.esgdbinit}
1233 CISCO 68k: @file{.cisco-gdbinit}
1238 @section Quitting @value{GDBN}
1239 @cindex exiting @value{GDBN}
1240 @cindex leaving @value{GDBN}
1243 @kindex quit @r{[}@var{expression}@r{]}
1244 @kindex q @r{(@code{quit})}
1245 @item quit @r{[}@var{expression}@r{]}
1247 To exit @value{GDBN}, use the @code{quit} command (abbreviated
1248 @code{q}), or type an end-of-file character (usually @kbd{C-d}). If you
1249 do not supply @var{expression}, @value{GDBN} will terminate normally;
1250 otherwise it will terminate using the result of @var{expression} as the
1255 An interrupt (often @kbd{C-c}) does not exit from @value{GDBN}, but rather
1256 terminates the action of any @value{GDBN} command that is in progress and
1257 returns to @value{GDBN} command level. It is safe to type the interrupt
1258 character at any time because @value{GDBN} does not allow it to take effect
1259 until a time when it is safe.
1261 If you have been using @value{GDBN} to control an attached process or
1262 device, you can release it with the @code{detach} command
1263 (@pxref{Attach, ,Debugging an already-running process}).
1265 @node Shell Commands
1266 @section Shell commands
1268 If you need to execute occasional shell commands during your
1269 debugging session, there is no need to leave or suspend @value{GDBN}; you can
1270 just use the @code{shell} command.
1274 @cindex shell escape
1275 @item shell @var{command string}
1276 Invoke a standard shell to execute @var{command string}.
1277 If it exists, the environment variable @code{SHELL} determines which
1278 shell to run. Otherwise @value{GDBN} uses the default shell
1279 (@file{/bin/sh} on Unix systems, @file{COMMAND.COM} on MS-DOS, etc.).
1282 The utility @code{make} is often needed in development environments.
1283 You do not have to use the @code{shell} command for this purpose in
1288 @cindex calling make
1289 @item make @var{make-args}
1290 Execute the @code{make} program with the specified
1291 arguments. This is equivalent to @samp{shell make @var{make-args}}.
1294 @node Logging output
1295 @section Logging output
1296 @cindex logging @value{GDBN} output
1297 @cindex save @value{GDBN} output to a file
1299 You may want to save the output of @value{GDBN} commands to a file.
1300 There are several commands to control @value{GDBN}'s logging.
1304 @item set logging on
1306 @item set logging off
1308 @cindex logging file name
1309 @item set logging file @var{file}
1310 Change the name of the current logfile. The default logfile is @file{gdb.txt}.
1311 @item set logging overwrite [on|off]
1312 By default, @value{GDBN} will append to the logfile. Set @code{overwrite} if
1313 you want @code{set logging on} to overwrite the logfile instead.
1314 @item set logging redirect [on|off]
1315 By default, @value{GDBN} output will go to both the terminal and the logfile.
1316 Set @code{redirect} if you want output to go only to the log file.
1317 @kindex show logging
1319 Show the current values of the logging settings.
1323 @chapter @value{GDBN} Commands
1325 You can abbreviate a @value{GDBN} command to the first few letters of the command
1326 name, if that abbreviation is unambiguous; and you can repeat certain
1327 @value{GDBN} commands by typing just @key{RET}. You can also use the @key{TAB}
1328 key to get @value{GDBN} to fill out the rest of a word in a command (or to
1329 show you the alternatives available, if there is more than one possibility).
1332 * Command Syntax:: How to give commands to @value{GDBN}
1333 * Completion:: Command completion
1334 * Help:: How to ask @value{GDBN} for help
1337 @node Command Syntax
1338 @section Command syntax
1340 A @value{GDBN} command is a single line of input. There is no limit on
1341 how long it can be. It starts with a command name, which is followed by
1342 arguments whose meaning depends on the command name. For example, the
1343 command @code{step} accepts an argument which is the number of times to
1344 step, as in @samp{step 5}. You can also use the @code{step} command
1345 with no arguments. Some commands do not allow any arguments.
1347 @cindex abbreviation
1348 @value{GDBN} command names may always be truncated if that abbreviation is
1349 unambiguous. Other possible command abbreviations are listed in the
1350 documentation for individual commands. In some cases, even ambiguous
1351 abbreviations are allowed; for example, @code{s} is specially defined as
1352 equivalent to @code{step} even though there are other commands whose
1353 names start with @code{s}. You can test abbreviations by using them as
1354 arguments to the @code{help} command.
1356 @cindex repeating commands
1357 @kindex RET @r{(repeat last command)}
1358 A blank line as input to @value{GDBN} (typing just @key{RET}) means to
1359 repeat the previous command. Certain commands (for example, @code{run})
1360 will not repeat this way; these are commands whose unintentional
1361 repetition might cause trouble and which you are unlikely to want to
1362 repeat. User-defined commands can disable this feature; see
1363 @ref{Define, dont-repeat}.
1365 The @code{list} and @code{x} commands, when you repeat them with
1366 @key{RET}, construct new arguments rather than repeating
1367 exactly as typed. This permits easy scanning of source or memory.
1369 @value{GDBN} can also use @key{RET} in another way: to partition lengthy
1370 output, in a way similar to the common utility @code{more}
1371 (@pxref{Screen Size,,Screen size}). Since it is easy to press one
1372 @key{RET} too many in this situation, @value{GDBN} disables command
1373 repetition after any command that generates this sort of display.
1375 @kindex # @r{(a comment)}
1377 Any text from a @kbd{#} to the end of the line is a comment; it does
1378 nothing. This is useful mainly in command files (@pxref{Command
1379 Files,,Command files}).
1381 @cindex repeating command sequences
1382 @kindex C-o @r{(operate-and-get-next)}
1383 The @kbd{C-o} binding is useful for repeating a complex sequence of
1384 commands. This command accepts the current line, like @kbd{RET}, and
1385 then fetches the next line relative to the current line from the history
1389 @section Command completion
1392 @cindex word completion
1393 @value{GDBN} can fill in the rest of a word in a command for you, if there is
1394 only one possibility; it can also show you what the valid possibilities
1395 are for the next word in a command, at any time. This works for @value{GDBN}
1396 commands, @value{GDBN} subcommands, and the names of symbols in your program.
1398 Press the @key{TAB} key whenever you want @value{GDBN} to fill out the rest
1399 of a word. If there is only one possibility, @value{GDBN} fills in the
1400 word, and waits for you to finish the command (or press @key{RET} to
1401 enter it). For example, if you type
1403 @c FIXME "@key" does not distinguish its argument sufficiently to permit
1404 @c complete accuracy in these examples; space introduced for clarity.
1405 @c If texinfo enhancements make it unnecessary, it would be nice to
1406 @c replace " @key" by "@key" in the following...
1408 (@value{GDBP}) info bre @key{TAB}
1412 @value{GDBN} fills in the rest of the word @samp{breakpoints}, since that is
1413 the only @code{info} subcommand beginning with @samp{bre}:
1416 (@value{GDBP}) info breakpoints
1420 You can either press @key{RET} at this point, to run the @code{info
1421 breakpoints} command, or backspace and enter something else, if
1422 @samp{breakpoints} does not look like the command you expected. (If you
1423 were sure you wanted @code{info breakpoints} in the first place, you
1424 might as well just type @key{RET} immediately after @samp{info bre},
1425 to exploit command abbreviations rather than command completion).
1427 If there is more than one possibility for the next word when you press
1428 @key{TAB}, @value{GDBN} sounds a bell. You can either supply more
1429 characters and try again, or just press @key{TAB} a second time;
1430 @value{GDBN} displays all the possible completions for that word. For
1431 example, you might want to set a breakpoint on a subroutine whose name
1432 begins with @samp{make_}, but when you type @kbd{b make_@key{TAB}} @value{GDBN}
1433 just sounds the bell. Typing @key{TAB} again displays all the
1434 function names in your program that begin with those characters, for
1438 (@value{GDBP}) b make_ @key{TAB}
1439 @exdent @value{GDBN} sounds bell; press @key{TAB} again, to see:
1440 make_a_section_from_file make_environ
1441 make_abs_section make_function_type
1442 make_blockvector make_pointer_type
1443 make_cleanup make_reference_type
1444 make_command make_symbol_completion_list
1445 (@value{GDBP}) b make_
1449 After displaying the available possibilities, @value{GDBN} copies your
1450 partial input (@samp{b make_} in the example) so you can finish the
1453 If you just want to see the list of alternatives in the first place, you
1454 can press @kbd{M-?} rather than pressing @key{TAB} twice. @kbd{M-?}
1455 means @kbd{@key{META} ?}. You can type this either by holding down a
1456 key designated as the @key{META} shift on your keyboard (if there is
1457 one) while typing @kbd{?}, or as @key{ESC} followed by @kbd{?}.
1459 @cindex quotes in commands
1460 @cindex completion of quoted strings
1461 Sometimes the string you need, while logically a ``word'', may contain
1462 parentheses or other characters that @value{GDBN} normally excludes from
1463 its notion of a word. To permit word completion to work in this
1464 situation, you may enclose words in @code{'} (single quote marks) in
1465 @value{GDBN} commands.
1467 The most likely situation where you might need this is in typing the
1468 name of a C@t{++} function. This is because C@t{++} allows function
1469 overloading (multiple definitions of the same function, distinguished
1470 by argument type). For example, when you want to set a breakpoint you
1471 may need to distinguish whether you mean the version of @code{name}
1472 that takes an @code{int} parameter, @code{name(int)}, or the version
1473 that takes a @code{float} parameter, @code{name(float)}. To use the
1474 word-completion facilities in this situation, type a single quote
1475 @code{'} at the beginning of the function name. This alerts
1476 @value{GDBN} that it may need to consider more information than usual
1477 when you press @key{TAB} or @kbd{M-?} to request word completion:
1480 (@value{GDBP}) b 'bubble( @kbd{M-?}
1481 bubble(double,double) bubble(int,int)
1482 (@value{GDBP}) b 'bubble(
1485 In some cases, @value{GDBN} can tell that completing a name requires using
1486 quotes. When this happens, @value{GDBN} inserts the quote for you (while
1487 completing as much as it can) if you do not type the quote in the first
1491 (@value{GDBP}) b bub @key{TAB}
1492 @exdent @value{GDBN} alters your input line to the following, and rings a bell:
1493 (@value{GDBP}) b 'bubble(
1497 In general, @value{GDBN} can tell that a quote is needed (and inserts it) if
1498 you have not yet started typing the argument list when you ask for
1499 completion on an overloaded symbol.
1501 For more information about overloaded functions, see @ref{C plus plus
1502 expressions, ,C@t{++} expressions}. You can use the command @code{set
1503 overload-resolution off} to disable overload resolution;
1504 see @ref{Debugging C plus plus, ,@value{GDBN} features for C@t{++}}.
1508 @section Getting help
1509 @cindex online documentation
1512 You can always ask @value{GDBN} itself for information on its commands,
1513 using the command @code{help}.
1516 @kindex h @r{(@code{help})}
1519 You can use @code{help} (abbreviated @code{h}) with no arguments to
1520 display a short list of named classes of commands:
1524 List of classes of commands:
1526 aliases -- Aliases of other commands
1527 breakpoints -- Making program stop at certain points
1528 data -- Examining data
1529 files -- Specifying and examining files
1530 internals -- Maintenance commands
1531 obscure -- Obscure features
1532 running -- Running the program
1533 stack -- Examining the stack
1534 status -- Status inquiries
1535 support -- Support facilities
1536 tracepoints -- Tracing of program execution without@*
1537 stopping the program
1538 user-defined -- User-defined commands
1540 Type "help" followed by a class name for a list of
1541 commands in that class.
1542 Type "help" followed by command name for full
1544 Command name abbreviations are allowed if unambiguous.
1547 @c the above line break eliminates huge line overfull...
1549 @item help @var{class}
1550 Using one of the general help classes as an argument, you can get a
1551 list of the individual commands in that class. For example, here is the
1552 help display for the class @code{status}:
1555 (@value{GDBP}) help status
1560 @c Line break in "show" line falsifies real output, but needed
1561 @c to fit in smallbook page size.
1562 info -- Generic command for showing things
1563 about the program being debugged
1564 show -- Generic command for showing things
1567 Type "help" followed by command name for full
1569 Command name abbreviations are allowed if unambiguous.
1573 @item help @var{command}
1574 With a command name as @code{help} argument, @value{GDBN} displays a
1575 short paragraph on how to use that command.
1578 @item apropos @var{args}
1579 The @code{apropos} command searches through all of the @value{GDBN}
1580 commands, and their documentation, for the regular expression specified in
1581 @var{args}. It prints out all matches found. For example:
1592 set symbol-reloading -- Set dynamic symbol table reloading
1593 multiple times in one run
1594 show symbol-reloading -- Show dynamic symbol table reloading
1595 multiple times in one run
1600 @item complete @var{args}
1601 The @code{complete @var{args}} command lists all the possible completions
1602 for the beginning of a command. Use @var{args} to specify the beginning of the
1603 command you want completed. For example:
1609 @noindent results in:
1620 @noindent This is intended for use by @sc{gnu} Emacs.
1623 In addition to @code{help}, you can use the @value{GDBN} commands @code{info}
1624 and @code{show} to inquire about the state of your program, or the state
1625 of @value{GDBN} itself. Each command supports many topics of inquiry; this
1626 manual introduces each of them in the appropriate context. The listings
1627 under @code{info} and under @code{show} in the Index point to
1628 all the sub-commands. @xref{Index}.
1633 @kindex i @r{(@code{info})}
1635 This command (abbreviated @code{i}) is for describing the state of your
1636 program. For example, you can list the arguments given to your program
1637 with @code{info args}, list the registers currently in use with @code{info
1638 registers}, or list the breakpoints you have set with @code{info breakpoints}.
1639 You can get a complete list of the @code{info} sub-commands with
1640 @w{@code{help info}}.
1644 You can assign the result of an expression to an environment variable with
1645 @code{set}. For example, you can set the @value{GDBN} prompt to a $-sign with
1646 @code{set prompt $}.
1650 In contrast to @code{info}, @code{show} is for describing the state of
1651 @value{GDBN} itself.
1652 You can change most of the things you can @code{show}, by using the
1653 related command @code{set}; for example, you can control what number
1654 system is used for displays with @code{set radix}, or simply inquire
1655 which is currently in use with @code{show radix}.
1658 To display all the settable parameters and their current
1659 values, you can use @code{show} with no arguments; you may also use
1660 @code{info set}. Both commands produce the same display.
1661 @c FIXME: "info set" violates the rule that "info" is for state of
1662 @c FIXME...program. Ck w/ GNU: "info set" to be called something else,
1663 @c FIXME...or change desc of rule---eg "state of prog and debugging session"?
1667 Here are three miscellaneous @code{show} subcommands, all of which are
1668 exceptional in lacking corresponding @code{set} commands:
1671 @kindex show version
1672 @cindex @value{GDBN} version number
1674 Show what version of @value{GDBN} is running. You should include this
1675 information in @value{GDBN} bug-reports. If multiple versions of
1676 @value{GDBN} are in use at your site, you may need to determine which
1677 version of @value{GDBN} you are running; as @value{GDBN} evolves, new
1678 commands are introduced, and old ones may wither away. Also, many
1679 system vendors ship variant versions of @value{GDBN}, and there are
1680 variant versions of @value{GDBN} in @sc{gnu}/Linux distributions as well.
1681 The version number is the same as the one announced when you start
1684 @kindex show copying
1685 @kindex info copying
1686 @cindex display @value{GDBN} copyright
1689 Display information about permission for copying @value{GDBN}.
1691 @kindex show warranty
1692 @kindex info warranty
1694 @itemx info warranty
1695 Display the @sc{gnu} ``NO WARRANTY'' statement, or a warranty,
1696 if your version of @value{GDBN} comes with one.
1701 @chapter Running Programs Under @value{GDBN}
1703 When you run a program under @value{GDBN}, you must first generate
1704 debugging information when you compile it.
1706 You may start @value{GDBN} with its arguments, if any, in an environment
1707 of your choice. If you are doing native debugging, you may redirect
1708 your program's input and output, debug an already running process, or
1709 kill a child process.
1712 * Compilation:: Compiling for debugging
1713 * Starting:: Starting your program
1714 * Arguments:: Your program's arguments
1715 * Environment:: Your program's environment
1717 * Working Directory:: Your program's working directory
1718 * Input/Output:: Your program's input and output
1719 * Attach:: Debugging an already-running process
1720 * Kill Process:: Killing the child process
1722 * Threads:: Debugging programs with multiple threads
1723 * Processes:: Debugging programs with multiple processes
1727 @section Compiling for debugging
1729 In order to debug a program effectively, you need to generate
1730 debugging information when you compile it. This debugging information
1731 is stored in the object file; it describes the data type of each
1732 variable or function and the correspondence between source line numbers
1733 and addresses in the executable code.
1735 To request debugging information, specify the @samp{-g} option when you run
1738 Programs that are to be shipped to your customers are compiled with
1739 optimizations, using the @samp{-O} compiler option. However, many
1740 compilers are unable to handle the @samp{-g} and @samp{-O} options
1741 together. Using those compilers, you cannot generate optimized
1742 executables containing debugging information.
1744 @value{NGCC}, the @sc{gnu} C/C@t{++} compiler, supports @samp{-g} with or
1745 without @samp{-O}, making it possible to debug optimized code. We
1746 recommend that you @emph{always} use @samp{-g} whenever you compile a
1747 program. You may think your program is correct, but there is no sense
1748 in pushing your luck.
1750 @cindex optimized code, debugging
1751 @cindex debugging optimized code
1752 When you debug a program compiled with @samp{-g -O}, remember that the
1753 optimizer is rearranging your code; the debugger shows you what is
1754 really there. Do not be too surprised when the execution path does not
1755 exactly match your source file! An extreme example: if you define a
1756 variable, but never use it, @value{GDBN} never sees that
1757 variable---because the compiler optimizes it out of existence.
1759 Some things do not work as well with @samp{-g -O} as with just
1760 @samp{-g}, particularly on machines with instruction scheduling. If in
1761 doubt, recompile with @samp{-g} alone, and if this fixes the problem,
1762 please report it to us as a bug (including a test case!).
1763 @xref{Variables}, for more information about debugging optimized code.
1765 Older versions of the @sc{gnu} C compiler permitted a variant option
1766 @w{@samp{-gg}} for debugging information. @value{GDBN} no longer supports this
1767 format; if your @sc{gnu} C compiler has this option, do not use it.
1769 @value{GDBN} knows about preprocessor macros and can show you their
1770 expansion (@pxref{Macros}). Most compilers do not include information
1771 about preprocessor macros in the debugging information if you specify
1772 the @option{-g} flag alone, because this information is rather large.
1773 Version 3.1 and later of @value{NGCC}, the @sc{gnu} C compiler,
1774 provides macro information if you specify the options
1775 @option{-gdwarf-2} and @option{-g3}; the former option requests
1776 debugging information in the Dwarf 2 format, and the latter requests
1777 ``extra information''. In the future, we hope to find more compact
1778 ways to represent macro information, so that it can be included with
1783 @section Starting your program
1789 @kindex r @r{(@code{run})}
1792 Use the @code{run} command to start your program under @value{GDBN}.
1793 You must first specify the program name (except on VxWorks) with an
1794 argument to @value{GDBN} (@pxref{Invocation, ,Getting In and Out of
1795 @value{GDBN}}), or by using the @code{file} or @code{exec-file} command
1796 (@pxref{Files, ,Commands to specify files}).
1800 If you are running your program in an execution environment that
1801 supports processes, @code{run} creates an inferior process and makes
1802 that process run your program. (In environments without processes,
1803 @code{run} jumps to the start of your program.)
1805 The execution of a program is affected by certain information it
1806 receives from its superior. @value{GDBN} provides ways to specify this
1807 information, which you must do @emph{before} starting your program. (You
1808 can change it after starting your program, but such changes only affect
1809 your program the next time you start it.) This information may be
1810 divided into four categories:
1813 @item The @emph{arguments.}
1814 Specify the arguments to give your program as the arguments of the
1815 @code{run} command. If a shell is available on your target, the shell
1816 is used to pass the arguments, so that you may use normal conventions
1817 (such as wildcard expansion or variable substitution) in describing
1819 In Unix systems, you can control which shell is used with the
1820 @code{SHELL} environment variable.
1821 @xref{Arguments, ,Your program's arguments}.
1823 @item The @emph{environment.}
1824 Your program normally inherits its environment from @value{GDBN}, but you can
1825 use the @value{GDBN} commands @code{set environment} and @code{unset
1826 environment} to change parts of the environment that affect
1827 your program. @xref{Environment, ,Your program's environment}.
1829 @item The @emph{working directory.}
1830 Your program inherits its working directory from @value{GDBN}. You can set
1831 the @value{GDBN} working directory with the @code{cd} command in @value{GDBN}.
1832 @xref{Working Directory, ,Your program's working directory}.
1834 @item The @emph{standard input and output.}
1835 Your program normally uses the same device for standard input and
1836 standard output as @value{GDBN} is using. You can redirect input and output
1837 in the @code{run} command line, or you can use the @code{tty} command to
1838 set a different device for your program.
1839 @xref{Input/Output, ,Your program's input and output}.
1842 @emph{Warning:} While input and output redirection work, you cannot use
1843 pipes to pass the output of the program you are debugging to another
1844 program; if you attempt this, @value{GDBN} is likely to wind up debugging the
1848 When you issue the @code{run} command, your program begins to execute
1849 immediately. @xref{Stopping, ,Stopping and continuing}, for discussion
1850 of how to arrange for your program to stop. Once your program has
1851 stopped, you may call functions in your program, using the @code{print}
1852 or @code{call} commands. @xref{Data, ,Examining Data}.
1854 If the modification time of your symbol file has changed since the last
1855 time @value{GDBN} read its symbols, @value{GDBN} discards its symbol
1856 table, and reads it again. When it does this, @value{GDBN} tries to retain
1857 your current breakpoints.
1862 @cindex run to main procedure
1863 The name of the main procedure can vary from language to language.
1864 With C or C@t{++}, the main procedure name is always @code{main}, but
1865 other languages such as Ada do not require a specific name for their
1866 main procedure. The debugger provides a convenient way to start the
1867 execution of the program and to stop at the beginning of the main
1868 procedure, depending on the language used.
1870 The @samp{start} command does the equivalent of setting a temporary
1871 breakpoint at the beginning of the main procedure and then invoking
1872 the @samp{run} command.
1874 @cindex elaboration phase
1875 Some programs contain an @dfn{elaboration} phase where some startup code is
1876 executed before the main procedure is called. This depends on the
1877 languages used to write your program. In C@t{++}, for instance,
1878 constructors for static and global objects are executed before
1879 @code{main} is called. It is therefore possible that the debugger stops
1880 before reaching the main procedure. However, the temporary breakpoint
1881 will remain to halt execution.
1883 Specify the arguments to give to your program as arguments to the
1884 @samp{start} command. These arguments will be given verbatim to the
1885 underlying @samp{run} command. Note that the same arguments will be
1886 reused if no argument is provided during subsequent calls to
1887 @samp{start} or @samp{run}.
1889 It is sometimes necessary to debug the program during elaboration. In
1890 these cases, using the @code{start} command would stop the execution of
1891 your program too late, as the program would have already completed the
1892 elaboration phase. Under these circumstances, insert breakpoints in your
1893 elaboration code before running your program.
1897 @section Your program's arguments
1899 @cindex arguments (to your program)
1900 The arguments to your program can be specified by the arguments of the
1902 They are passed to a shell, which expands wildcard characters and
1903 performs redirection of I/O, and thence to your program. Your
1904 @code{SHELL} environment variable (if it exists) specifies what shell
1905 @value{GDBN} uses. If you do not define @code{SHELL}, @value{GDBN} uses
1906 the default shell (@file{/bin/sh} on Unix).
1908 On non-Unix systems, the program is usually invoked directly by
1909 @value{GDBN}, which emulates I/O redirection via the appropriate system
1910 calls, and the wildcard characters are expanded by the startup code of
1911 the program, not by the shell.
1913 @code{run} with no arguments uses the same arguments used by the previous
1914 @code{run}, or those set by the @code{set args} command.
1919 Specify the arguments to be used the next time your program is run. If
1920 @code{set args} has no arguments, @code{run} executes your program
1921 with no arguments. Once you have run your program with arguments,
1922 using @code{set args} before the next @code{run} is the only way to run
1923 it again without arguments.
1927 Show the arguments to give your program when it is started.
1931 @section Your program's environment
1933 @cindex environment (of your program)
1934 The @dfn{environment} consists of a set of environment variables and
1935 their values. Environment variables conventionally record such things as
1936 your user name, your home directory, your terminal type, and your search
1937 path for programs to run. Usually you set up environment variables with
1938 the shell and they are inherited by all the other programs you run. When
1939 debugging, it can be useful to try running your program with a modified
1940 environment without having to start @value{GDBN} over again.
1944 @item path @var{directory}
1945 Add @var{directory} to the front of the @code{PATH} environment variable
1946 (the search path for executables) that will be passed to your program.
1947 The value of @code{PATH} used by @value{GDBN} does not change.
1948 You may specify several directory names, separated by whitespace or by a
1949 system-dependent separator character (@samp{:} on Unix, @samp{;} on
1950 MS-DOS and MS-Windows). If @var{directory} is already in the path, it
1951 is moved to the front, so it is searched sooner.
1953 You can use the string @samp{$cwd} to refer to whatever is the current
1954 working directory at the time @value{GDBN} searches the path. If you
1955 use @samp{.} instead, it refers to the directory where you executed the
1956 @code{path} command. @value{GDBN} replaces @samp{.} in the
1957 @var{directory} argument (with the current path) before adding
1958 @var{directory} to the search path.
1959 @c 'path' is explicitly nonrepeatable, but RMS points out it is silly to
1960 @c document that, since repeating it would be a no-op.
1964 Display the list of search paths for executables (the @code{PATH}
1965 environment variable).
1967 @kindex show environment
1968 @item show environment @r{[}@var{varname}@r{]}
1969 Print the value of environment variable @var{varname} to be given to
1970 your program when it starts. If you do not supply @var{varname},
1971 print the names and values of all environment variables to be given to
1972 your program. You can abbreviate @code{environment} as @code{env}.
1974 @kindex set environment
1975 @item set environment @var{varname} @r{[}=@var{value}@r{]}
1976 Set environment variable @var{varname} to @var{value}. The value
1977 changes for your program only, not for @value{GDBN} itself. @var{value} may
1978 be any string; the values of environment variables are just strings, and
1979 any interpretation is supplied by your program itself. The @var{value}
1980 parameter is optional; if it is eliminated, the variable is set to a
1982 @c "any string" here does not include leading, trailing
1983 @c blanks. Gnu asks: does anyone care?
1985 For example, this command:
1992 tells the debugged program, when subsequently run, that its user is named
1993 @samp{foo}. (The spaces around @samp{=} are used for clarity here; they
1994 are not actually required.)
1996 @kindex unset environment
1997 @item unset environment @var{varname}
1998 Remove variable @var{varname} from the environment to be passed to your
1999 program. This is different from @samp{set env @var{varname} =};
2000 @code{unset environment} removes the variable from the environment,
2001 rather than assigning it an empty value.
2004 @emph{Warning:} On Unix systems, @value{GDBN} runs your program using
2006 by your @code{SHELL} environment variable if it exists (or
2007 @code{/bin/sh} if not). If your @code{SHELL} variable names a shell
2008 that runs an initialization file---such as @file{.cshrc} for C-shell, or
2009 @file{.bashrc} for BASH---any variables you set in that file affect
2010 your program. You may wish to move setting of environment variables to
2011 files that are only run when you sign on, such as @file{.login} or
2014 @node Working Directory
2015 @section Your program's working directory
2017 @cindex working directory (of your program)
2018 Each time you start your program with @code{run}, it inherits its
2019 working directory from the current working directory of @value{GDBN}.
2020 The @value{GDBN} working directory is initially whatever it inherited
2021 from its parent process (typically the shell), but you can specify a new
2022 working directory in @value{GDBN} with the @code{cd} command.
2024 The @value{GDBN} working directory also serves as a default for the commands
2025 that specify files for @value{GDBN} to operate on. @xref{Files, ,Commands to
2030 @cindex change working directory
2031 @item cd @var{directory}
2032 Set the @value{GDBN} working directory to @var{directory}.
2036 Print the @value{GDBN} working directory.
2039 It is generally impossible to find the current working directory of
2040 the process being debugged (since a program can change its directory
2041 during its run). If you work on a system where @value{GDBN} is
2042 configured with the @file{/proc} support, you can use the @code{info
2043 proc} command (@pxref{SVR4 Process Information}) to find out the
2044 current working directory of the debuggee.
2047 @section Your program's input and output
2052 By default, the program you run under @value{GDBN} does input and output to
2053 the same terminal that @value{GDBN} uses. @value{GDBN} switches the terminal
2054 to its own terminal modes to interact with you, but it records the terminal
2055 modes your program was using and switches back to them when you continue
2056 running your program.
2059 @kindex info terminal
2061 Displays information recorded by @value{GDBN} about the terminal modes your
2065 You can redirect your program's input and/or output using shell
2066 redirection with the @code{run} command. For example,
2073 starts your program, diverting its output to the file @file{outfile}.
2076 @cindex controlling terminal
2077 Another way to specify where your program should do input and output is
2078 with the @code{tty} command. This command accepts a file name as
2079 argument, and causes this file to be the default for future @code{run}
2080 commands. It also resets the controlling terminal for the child
2081 process, for future @code{run} commands. For example,
2088 directs that processes started with subsequent @code{run} commands
2089 default to do input and output on the terminal @file{/dev/ttyb} and have
2090 that as their controlling terminal.
2092 An explicit redirection in @code{run} overrides the @code{tty} command's
2093 effect on the input/output device, but not its effect on the controlling
2096 When you use the @code{tty} command or redirect input in the @code{run}
2097 command, only the input @emph{for your program} is affected. The input
2098 for @value{GDBN} still comes from your terminal. @code{tty} is an alias
2099 for @code{set inferior-tty}.
2101 @cindex inferior tty
2102 @cindex set inferior controlling terminal
2103 You can use the @code{show inferior-tty} command to tell @value{GDBN} to
2104 display the name of the terminal that will be used for future runs of your
2108 @item set inferior-tty /dev/ttyb
2109 @kindex set inferior-tty
2110 Set the tty for the program being debugged to /dev/ttyb.
2112 @item show inferior-tty
2113 @kindex show inferior-tty
2114 Show the current tty for the program being debugged.
2118 @section Debugging an already-running process
2123 @item attach @var{process-id}
2124 This command attaches to a running process---one that was started
2125 outside @value{GDBN}. (@code{info files} shows your active
2126 targets.) The command takes as argument a process ID. The usual way to
2127 find out the @var{process-id} of a Unix process is with the @code{ps} utility,
2128 or with the @samp{jobs -l} shell command.
2130 @code{attach} does not repeat if you press @key{RET} a second time after
2131 executing the command.
2134 To use @code{attach}, your program must be running in an environment
2135 which supports processes; for example, @code{attach} does not work for
2136 programs on bare-board targets that lack an operating system. You must
2137 also have permission to send the process a signal.
2139 When you use @code{attach}, the debugger finds the program running in
2140 the process first by looking in the current working directory, then (if
2141 the program is not found) by using the source file search path
2142 (@pxref{Source Path, ,Specifying source directories}). You can also use
2143 the @code{file} command to load the program. @xref{Files, ,Commands to
2146 The first thing @value{GDBN} does after arranging to debug the specified
2147 process is to stop it. You can examine and modify an attached process
2148 with all the @value{GDBN} commands that are ordinarily available when
2149 you start processes with @code{run}. You can insert breakpoints; you
2150 can step and continue; you can modify storage. If you would rather the
2151 process continue running, you may use the @code{continue} command after
2152 attaching @value{GDBN} to the process.
2157 When you have finished debugging the attached process, you can use the
2158 @code{detach} command to release it from @value{GDBN} control. Detaching
2159 the process continues its execution. After the @code{detach} command,
2160 that process and @value{GDBN} become completely independent once more, and you
2161 are ready to @code{attach} another process or start one with @code{run}.
2162 @code{detach} does not repeat if you press @key{RET} again after
2163 executing the command.
2166 If you exit @value{GDBN} or use the @code{run} command while you have an
2167 attached process, you kill that process. By default, @value{GDBN} asks
2168 for confirmation if you try to do either of these things; you can
2169 control whether or not you need to confirm by using the @code{set
2170 confirm} command (@pxref{Messages/Warnings, ,Optional warnings and
2174 @section Killing the child process
2179 Kill the child process in which your program is running under @value{GDBN}.
2182 This command is useful if you wish to debug a core dump instead of a
2183 running process. @value{GDBN} ignores any core dump file while your program
2186 On some operating systems, a program cannot be executed outside @value{GDBN}
2187 while you have breakpoints set on it inside @value{GDBN}. You can use the
2188 @code{kill} command in this situation to permit running your program
2189 outside the debugger.
2191 The @code{kill} command is also useful if you wish to recompile and
2192 relink your program, since on many systems it is impossible to modify an
2193 executable file while it is running in a process. In this case, when you
2194 next type @code{run}, @value{GDBN} notices that the file has changed, and
2195 reads the symbol table again (while trying to preserve your current
2196 breakpoint settings).
2199 @section Debugging programs with multiple threads
2201 @cindex threads of execution
2202 @cindex multiple threads
2203 @cindex switching threads
2204 In some operating systems, such as HP-UX and Solaris, a single program
2205 may have more than one @dfn{thread} of execution. The precise semantics
2206 of threads differ from one operating system to another, but in general
2207 the threads of a single program are akin to multiple processes---except
2208 that they share one address space (that is, they can all examine and
2209 modify the same variables). On the other hand, each thread has its own
2210 registers and execution stack, and perhaps private memory.
2212 @value{GDBN} provides these facilities for debugging multi-thread
2216 @item automatic notification of new threads
2217 @item @samp{thread @var{threadno}}, a command to switch among threads
2218 @item @samp{info threads}, a command to inquire about existing threads
2219 @item @samp{thread apply [@var{threadno}] [@var{all}] @var{args}},
2220 a command to apply a command to a list of threads
2221 @item thread-specific breakpoints
2225 @emph{Warning:} These facilities are not yet available on every
2226 @value{GDBN} configuration where the operating system supports threads.
2227 If your @value{GDBN} does not support threads, these commands have no
2228 effect. For example, a system without thread support shows no output
2229 from @samp{info threads}, and always rejects the @code{thread} command,
2233 (@value{GDBP}) info threads
2234 (@value{GDBP}) thread 1
2235 Thread ID 1 not known. Use the "info threads" command to
2236 see the IDs of currently known threads.
2238 @c FIXME to implementors: how hard would it be to say "sorry, this GDB
2239 @c doesn't support threads"?
2242 @cindex focus of debugging
2243 @cindex current thread
2244 The @value{GDBN} thread debugging facility allows you to observe all
2245 threads while your program runs---but whenever @value{GDBN} takes
2246 control, one thread in particular is always the focus of debugging.
2247 This thread is called the @dfn{current thread}. Debugging commands show
2248 program information from the perspective of the current thread.
2250 @cindex @code{New} @var{systag} message
2251 @cindex thread identifier (system)
2252 @c FIXME-implementors!! It would be more helpful if the [New...] message
2253 @c included GDB's numeric thread handle, so you could just go to that
2254 @c thread without first checking `info threads'.
2255 Whenever @value{GDBN} detects a new thread in your program, it displays
2256 the target system's identification for the thread with a message in the
2257 form @samp{[New @var{systag}]}. @var{systag} is a thread identifier
2258 whose form varies depending on the particular system. For example, on
2259 LynxOS, you might see
2262 [New process 35 thread 27]
2266 when @value{GDBN} notices a new thread. In contrast, on an SGI system,
2267 the @var{systag} is simply something like @samp{process 368}, with no
2270 @c FIXME!! (1) Does the [New...] message appear even for the very first
2271 @c thread of a program, or does it only appear for the
2272 @c second---i.e.@: when it becomes obvious we have a multithread
2274 @c (2) *Is* there necessarily a first thread always? Or do some
2275 @c multithread systems permit starting a program with multiple
2276 @c threads ab initio?
2278 @cindex thread number
2279 @cindex thread identifier (GDB)
2280 For debugging purposes, @value{GDBN} associates its own thread
2281 number---always a single integer---with each thread in your program.
2284 @kindex info threads
2286 Display a summary of all threads currently in your
2287 program. @value{GDBN} displays for each thread (in this order):
2291 the thread number assigned by @value{GDBN}
2294 the target system's thread identifier (@var{systag})
2297 the current stack frame summary for that thread
2301 An asterisk @samp{*} to the left of the @value{GDBN} thread number
2302 indicates the current thread.
2306 @c end table here to get a little more width for example
2309 (@value{GDBP}) info threads
2310 3 process 35 thread 27 0x34e5 in sigpause ()
2311 2 process 35 thread 23 0x34e5 in sigpause ()
2312 * 1 process 35 thread 13 main (argc=1, argv=0x7ffffff8)
2318 @cindex debugging multithreaded programs (on HP-UX)
2319 @cindex thread identifier (GDB), on HP-UX
2320 For debugging purposes, @value{GDBN} associates its own thread
2321 number---a small integer assigned in thread-creation order---with each
2322 thread in your program.
2324 @cindex @code{New} @var{systag} message, on HP-UX
2325 @cindex thread identifier (system), on HP-UX
2326 @c FIXME-implementors!! It would be more helpful if the [New...] message
2327 @c included GDB's numeric thread handle, so you could just go to that
2328 @c thread without first checking `info threads'.
2329 Whenever @value{GDBN} detects a new thread in your program, it displays
2330 both @value{GDBN}'s thread number and the target system's identification for the thread with a message in the
2331 form @samp{[New @var{systag}]}. @var{systag} is a thread identifier
2332 whose form varies depending on the particular system. For example, on
2336 [New thread 2 (system thread 26594)]
2340 when @value{GDBN} notices a new thread.
2343 @kindex info threads (HP-UX)
2345 Display a summary of all threads currently in your
2346 program. @value{GDBN} displays for each thread (in this order):
2349 @item the thread number assigned by @value{GDBN}
2351 @item the target system's thread identifier (@var{systag})
2353 @item the current stack frame summary for that thread
2357 An asterisk @samp{*} to the left of the @value{GDBN} thread number
2358 indicates the current thread.
2362 @c end table here to get a little more width for example
2365 (@value{GDBP}) info threads
2366 * 3 system thread 26607 worker (wptr=0x7b09c318 "@@") \@*
2368 2 system thread 26606 0x7b0030d8 in __ksleep () \@*
2369 from /usr/lib/libc.2
2370 1 system thread 27905 0x7b003498 in _brk () \@*
2371 from /usr/lib/libc.2
2374 On Solaris, you can display more information about user threads with a
2375 Solaris-specific command:
2378 @item maint info sol-threads
2379 @kindex maint info sol-threads
2380 @cindex thread info (Solaris)
2381 Display info on Solaris user threads.
2385 @kindex thread @var{threadno}
2386 @item thread @var{threadno}
2387 Make thread number @var{threadno} the current thread. The command
2388 argument @var{threadno} is the internal @value{GDBN} thread number, as
2389 shown in the first field of the @samp{info threads} display.
2390 @value{GDBN} responds by displaying the system identifier of the thread
2391 you selected, and its current stack frame summary:
2394 @c FIXME!! This example made up; find a @value{GDBN} w/threads and get real one
2395 (@value{GDBP}) thread 2
2396 [Switching to process 35 thread 23]
2397 0x34e5 in sigpause ()
2401 As with the @samp{[New @dots{}]} message, the form of the text after
2402 @samp{Switching to} depends on your system's conventions for identifying
2405 @kindex thread apply
2406 @cindex apply command to several threads
2407 @item thread apply [@var{threadno}] [@var{all}] @var{args}
2408 The @code{thread apply} command allows you to apply a command to one or
2409 more threads. Specify the numbers of the threads that you want affected
2410 with the command argument @var{threadno}. @var{threadno} is the internal
2411 @value{GDBN} thread number, as shown in the first field of the @samp{info
2412 threads} display. To apply a command to all threads, use
2413 @code{thread apply all} @var{args}.
2416 @cindex automatic thread selection
2417 @cindex switching threads automatically
2418 @cindex threads, automatic switching
2419 Whenever @value{GDBN} stops your program, due to a breakpoint or a
2420 signal, it automatically selects the thread where that breakpoint or
2421 signal happened. @value{GDBN} alerts you to the context switch with a
2422 message of the form @samp{[Switching to @var{systag}]} to identify the
2425 @xref{Thread Stops,,Stopping and starting multi-thread programs}, for
2426 more information about how @value{GDBN} behaves when you stop and start
2427 programs with multiple threads.
2429 @xref{Set Watchpoints,,Setting watchpoints}, for information about
2430 watchpoints in programs with multiple threads.
2433 @section Debugging programs with multiple processes
2435 @cindex fork, debugging programs which call
2436 @cindex multiple processes
2437 @cindex processes, multiple
2438 On most systems, @value{GDBN} has no special support for debugging
2439 programs which create additional processes using the @code{fork}
2440 function. When a program forks, @value{GDBN} will continue to debug the
2441 parent process and the child process will run unimpeded. If you have
2442 set a breakpoint in any code which the child then executes, the child
2443 will get a @code{SIGTRAP} signal which (unless it catches the signal)
2444 will cause it to terminate.
2446 However, if you want to debug the child process there is a workaround
2447 which isn't too painful. Put a call to @code{sleep} in the code which
2448 the child process executes after the fork. It may be useful to sleep
2449 only if a certain environment variable is set, or a certain file exists,
2450 so that the delay need not occur when you don't want to run @value{GDBN}
2451 on the child. While the child is sleeping, use the @code{ps} program to
2452 get its process ID. Then tell @value{GDBN} (a new invocation of
2453 @value{GDBN} if you are also debugging the parent process) to attach to
2454 the child process (@pxref{Attach}). From that point on you can debug
2455 the child process just like any other process which you attached to.
2457 On some systems, @value{GDBN} provides support for debugging programs that
2458 create additional processes using the @code{fork} or @code{vfork} functions.
2459 Currently, the only platforms with this feature are HP-UX (11.x and later
2460 only?) and GNU/Linux (kernel version 2.5.60 and later).
2462 By default, when a program forks, @value{GDBN} will continue to debug
2463 the parent process and the child process will run unimpeded.
2465 If you want to follow the child process instead of the parent process,
2466 use the command @w{@code{set follow-fork-mode}}.
2469 @kindex set follow-fork-mode
2470 @item set follow-fork-mode @var{mode}
2471 Set the debugger response to a program call of @code{fork} or
2472 @code{vfork}. A call to @code{fork} or @code{vfork} creates a new
2473 process. The @var{mode} argument can be:
2477 The original process is debugged after a fork. The child process runs
2478 unimpeded. This is the default.
2481 The new process is debugged after a fork. The parent process runs
2486 @kindex show follow-fork-mode
2487 @item show follow-fork-mode
2488 Display the current debugger response to a @code{fork} or @code{vfork} call.
2491 If you ask to debug a child process and a @code{vfork} is followed by an
2492 @code{exec}, @value{GDBN} executes the new target up to the first
2493 breakpoint in the new target. If you have a breakpoint set on
2494 @code{main} in your original program, the breakpoint will also be set on
2495 the child process's @code{main}.
2497 When a child process is spawned by @code{vfork}, you cannot debug the
2498 child or parent until an @code{exec} call completes.
2500 If you issue a @code{run} command to @value{GDBN} after an @code{exec}
2501 call executes, the new target restarts. To restart the parent process,
2502 use the @code{file} command with the parent executable name as its
2505 You can use the @code{catch} command to make @value{GDBN} stop whenever
2506 a @code{fork}, @code{vfork}, or @code{exec} call is made. @xref{Set
2507 Catchpoints, ,Setting catchpoints}.
2510 @chapter Stopping and Continuing
2512 The principal purposes of using a debugger are so that you can stop your
2513 program before it terminates; or so that, if your program runs into
2514 trouble, you can investigate and find out why.
2516 Inside @value{GDBN}, your program may stop for any of several reasons,
2517 such as a signal, a breakpoint, or reaching a new line after a
2518 @value{GDBN} command such as @code{step}. You may then examine and
2519 change variables, set new breakpoints or remove old ones, and then
2520 continue execution. Usually, the messages shown by @value{GDBN} provide
2521 ample explanation of the status of your program---but you can also
2522 explicitly request this information at any time.
2525 @kindex info program
2527 Display information about the status of your program: whether it is
2528 running or not, what process it is, and why it stopped.
2532 * Breakpoints:: Breakpoints, watchpoints, and catchpoints
2533 * Continuing and Stepping:: Resuming execution
2535 * Thread Stops:: Stopping and starting multi-thread programs
2539 @section Breakpoints, watchpoints, and catchpoints
2542 A @dfn{breakpoint} makes your program stop whenever a certain point in
2543 the program is reached. For each breakpoint, you can add conditions to
2544 control in finer detail whether your program stops. You can set
2545 breakpoints with the @code{break} command and its variants (@pxref{Set
2546 Breaks, ,Setting breakpoints}), to specify the place where your program
2547 should stop by line number, function name or exact address in the
2550 On some systems, you can set breakpoints in shared libraries before
2551 the executable is run. There is a minor limitation on HP-UX systems:
2552 you must wait until the executable is run in order to set breakpoints
2553 in shared library routines that are not called directly by the program
2554 (for example, routines that are arguments in a @code{pthread_create}
2558 @cindex memory tracing
2559 @cindex breakpoint on memory address
2560 @cindex breakpoint on variable modification
2561 A @dfn{watchpoint} is a special breakpoint that stops your program
2562 when the value of an expression changes. You must use a different
2563 command to set watchpoints (@pxref{Set Watchpoints, ,Setting
2564 watchpoints}), but aside from that, you can manage a watchpoint like
2565 any other breakpoint: you enable, disable, and delete both breakpoints
2566 and watchpoints using the same commands.
2568 You can arrange to have values from your program displayed automatically
2569 whenever @value{GDBN} stops at a breakpoint. @xref{Auto Display,,
2573 @cindex breakpoint on events
2574 A @dfn{catchpoint} is another special breakpoint that stops your program
2575 when a certain kind of event occurs, such as the throwing of a C@t{++}
2576 exception or the loading of a library. As with watchpoints, you use a
2577 different command to set a catchpoint (@pxref{Set Catchpoints, ,Setting
2578 catchpoints}), but aside from that, you can manage a catchpoint like any
2579 other breakpoint. (To stop when your program receives a signal, use the
2580 @code{handle} command; see @ref{Signals, ,Signals}.)
2582 @cindex breakpoint numbers
2583 @cindex numbers for breakpoints
2584 @value{GDBN} assigns a number to each breakpoint, watchpoint, or
2585 catchpoint when you create it; these numbers are successive integers
2586 starting with one. In many of the commands for controlling various
2587 features of breakpoints you use the breakpoint number to say which
2588 breakpoint you want to change. Each breakpoint may be @dfn{enabled} or
2589 @dfn{disabled}; if disabled, it has no effect on your program until you
2592 @cindex breakpoint ranges
2593 @cindex ranges of breakpoints
2594 Some @value{GDBN} commands accept a range of breakpoints on which to
2595 operate. A breakpoint range is either a single breakpoint number, like
2596 @samp{5}, or two such numbers, in increasing order, separated by a
2597 hyphen, like @samp{5-7}. When a breakpoint range is given to a command,
2598 all breakpoint in that range are operated on.
2601 * Set Breaks:: Setting breakpoints
2602 * Set Watchpoints:: Setting watchpoints
2603 * Set Catchpoints:: Setting catchpoints
2604 * Delete Breaks:: Deleting breakpoints
2605 * Disabling:: Disabling breakpoints
2606 * Conditions:: Break conditions
2607 * Break Commands:: Breakpoint command lists
2608 * Breakpoint Menus:: Breakpoint menus
2609 * Error in Breakpoints:: ``Cannot insert breakpoints''
2610 * Breakpoint related warnings:: ``Breakpoint address adjusted...''
2614 @subsection Setting breakpoints
2616 @c FIXME LMB what does GDB do if no code on line of breakpt?
2617 @c consider in particular declaration with/without initialization.
2619 @c FIXME 2 is there stuff on this already? break at fun start, already init?
2622 @kindex b @r{(@code{break})}
2623 @vindex $bpnum@r{, convenience variable}
2624 @cindex latest breakpoint
2625 Breakpoints are set with the @code{break} command (abbreviated
2626 @code{b}). The debugger convenience variable @samp{$bpnum} records the
2627 number of the breakpoint you've set most recently; see @ref{Convenience
2628 Vars,, Convenience variables}, for a discussion of what you can do with
2629 convenience variables.
2631 You have several ways to say where the breakpoint should go.
2634 @item break @var{function}
2635 Set a breakpoint at entry to function @var{function}.
2636 When using source languages that permit overloading of symbols, such as
2637 C@t{++}, @var{function} may refer to more than one possible place to break.
2638 @xref{Breakpoint Menus,,Breakpoint menus}, for a discussion of that situation.
2640 @item break +@var{offset}
2641 @itemx break -@var{offset}
2642 Set a breakpoint some number of lines forward or back from the position
2643 at which execution stopped in the currently selected @dfn{stack frame}.
2644 (@xref{Frames, ,Frames}, for a description of stack frames.)
2646 @item break @var{linenum}
2647 Set a breakpoint at line @var{linenum} in the current source file.
2648 The current source file is the last file whose source text was printed.
2649 The breakpoint will stop your program just before it executes any of the
2652 @item break @var{filename}:@var{linenum}
2653 Set a breakpoint at line @var{linenum} in source file @var{filename}.
2655 @item break @var{filename}:@var{function}
2656 Set a breakpoint at entry to function @var{function} found in file
2657 @var{filename}. Specifying a file name as well as a function name is
2658 superfluous except when multiple files contain similarly named
2661 @item break *@var{address}
2662 Set a breakpoint at address @var{address}. You can use this to set
2663 breakpoints in parts of your program which do not have debugging
2664 information or source files.
2667 When called without any arguments, @code{break} sets a breakpoint at
2668 the next instruction to be executed in the selected stack frame
2669 (@pxref{Stack, ,Examining the Stack}). In any selected frame but the
2670 innermost, this makes your program stop as soon as control
2671 returns to that frame. This is similar to the effect of a
2672 @code{finish} command in the frame inside the selected frame---except
2673 that @code{finish} does not leave an active breakpoint. If you use
2674 @code{break} without an argument in the innermost frame, @value{GDBN} stops
2675 the next time it reaches the current location; this may be useful
2678 @value{GDBN} normally ignores breakpoints when it resumes execution, until at
2679 least one instruction has been executed. If it did not do this, you
2680 would be unable to proceed past a breakpoint without first disabling the
2681 breakpoint. This rule applies whether or not the breakpoint already
2682 existed when your program stopped.
2684 @item break @dots{} if @var{cond}
2685 Set a breakpoint with condition @var{cond}; evaluate the expression
2686 @var{cond} each time the breakpoint is reached, and stop only if the
2687 value is nonzero---that is, if @var{cond} evaluates as true.
2688 @samp{@dots{}} stands for one of the possible arguments described
2689 above (or no argument) specifying where to break. @xref{Conditions,
2690 ,Break conditions}, for more information on breakpoint conditions.
2693 @item tbreak @var{args}
2694 Set a breakpoint enabled only for one stop. @var{args} are the
2695 same as for the @code{break} command, and the breakpoint is set in the same
2696 way, but the breakpoint is automatically deleted after the first time your
2697 program stops there. @xref{Disabling, ,Disabling breakpoints}.
2700 @cindex hardware breakpoints
2701 @item hbreak @var{args}
2702 Set a hardware-assisted breakpoint. @var{args} are the same as for the
2703 @code{break} command and the breakpoint is set in the same way, but the
2704 breakpoint requires hardware support and some target hardware may not
2705 have this support. The main purpose of this is EPROM/ROM code
2706 debugging, so you can set a breakpoint at an instruction without
2707 changing the instruction. This can be used with the new trap-generation
2708 provided by SPARClite DSU and most x86-based targets. These targets
2709 will generate traps when a program accesses some data or instruction
2710 address that is assigned to the debug registers. However the hardware
2711 breakpoint registers can take a limited number of breakpoints. For
2712 example, on the DSU, only two data breakpoints can be set at a time, and
2713 @value{GDBN} will reject this command if more than two are used. Delete
2714 or disable unused hardware breakpoints before setting new ones
2715 (@pxref{Disabling, ,Disabling}). @xref{Conditions, ,Break conditions}.
2716 For remote targets, you can restrict the number of hardware
2717 breakpoints @value{GDBN} will use, see @ref{set remote
2718 hardware-breakpoint-limit}.
2722 @item thbreak @var{args}
2723 Set a hardware-assisted breakpoint enabled only for one stop. @var{args}
2724 are the same as for the @code{hbreak} command and the breakpoint is set in
2725 the same way. However, like the @code{tbreak} command,
2726 the breakpoint is automatically deleted after the
2727 first time your program stops there. Also, like the @code{hbreak}
2728 command, the breakpoint requires hardware support and some target hardware
2729 may not have this support. @xref{Disabling, ,Disabling breakpoints}.
2730 See also @ref{Conditions, ,Break conditions}.
2733 @cindex regular expression
2734 @cindex breakpoints in functions matching a regexp
2735 @cindex set breakpoints in many functions
2736 @item rbreak @var{regex}
2737 Set breakpoints on all functions matching the regular expression
2738 @var{regex}. This command sets an unconditional breakpoint on all
2739 matches, printing a list of all breakpoints it set. Once these
2740 breakpoints are set, they are treated just like the breakpoints set with
2741 the @code{break} command. You can delete them, disable them, or make
2742 them conditional the same way as any other breakpoint.
2744 The syntax of the regular expression is the standard one used with tools
2745 like @file{grep}. Note that this is different from the syntax used by
2746 shells, so for instance @code{foo*} matches all functions that include
2747 an @code{fo} followed by zero or more @code{o}s. There is an implicit
2748 @code{.*} leading and trailing the regular expression you supply, so to
2749 match only functions that begin with @code{foo}, use @code{^foo}.
2751 @cindex non-member C@t{++} functions, set breakpoint in
2752 When debugging C@t{++} programs, @code{rbreak} is useful for setting
2753 breakpoints on overloaded functions that are not members of any special
2756 @cindex set breakpoints on all functions
2757 The @code{rbreak} command can be used to set breakpoints in
2758 @strong{all} the functions in a program, like this:
2761 (@value{GDBP}) rbreak .
2764 @kindex info breakpoints
2765 @cindex @code{$_} and @code{info breakpoints}
2766 @item info breakpoints @r{[}@var{n}@r{]}
2767 @itemx info break @r{[}@var{n}@r{]}
2768 @itemx info watchpoints @r{[}@var{n}@r{]}
2769 Print a table of all breakpoints, watchpoints, and catchpoints set and
2770 not deleted, with the following columns for each breakpoint:
2773 @item Breakpoint Numbers
2775 Breakpoint, watchpoint, or catchpoint.
2777 Whether the breakpoint is marked to be disabled or deleted when hit.
2778 @item Enabled or Disabled
2779 Enabled breakpoints are marked with @samp{y}. @samp{n} marks breakpoints
2780 that are not enabled.
2782 Where the breakpoint is in your program, as a memory address. If the
2783 breakpoint is pending (see below for details) on a future load of a shared library, the address
2784 will be listed as @samp{<PENDING>}.
2786 Where the breakpoint is in the source for your program, as a file and
2787 line number. For a pending breakpoint, the original string passed to
2788 the breakpoint command will be listed as it cannot be resolved until
2789 the appropriate shared library is loaded in the future.
2793 If a breakpoint is conditional, @code{info break} shows the condition on
2794 the line following the affected breakpoint; breakpoint commands, if any,
2795 are listed after that. A pending breakpoint is allowed to have a condition
2796 specified for it. The condition is not parsed for validity until a shared
2797 library is loaded that allows the pending breakpoint to resolve to a
2801 @code{info break} with a breakpoint
2802 number @var{n} as argument lists only that breakpoint. The
2803 convenience variable @code{$_} and the default examining-address for
2804 the @code{x} command are set to the address of the last breakpoint
2805 listed (@pxref{Memory, ,Examining memory}).
2808 @code{info break} displays a count of the number of times the breakpoint
2809 has been hit. This is especially useful in conjunction with the
2810 @code{ignore} command. You can ignore a large number of breakpoint
2811 hits, look at the breakpoint info to see how many times the breakpoint
2812 was hit, and then run again, ignoring one less than that number. This
2813 will get you quickly to the last hit of that breakpoint.
2816 @value{GDBN} allows you to set any number of breakpoints at the same place in
2817 your program. There is nothing silly or meaningless about this. When
2818 the breakpoints are conditional, this is even useful
2819 (@pxref{Conditions, ,Break conditions}).
2821 @cindex pending breakpoints
2822 If a specified breakpoint location cannot be found, it may be due to the fact
2823 that the location is in a shared library that is yet to be loaded. In such
2824 a case, you may want @value{GDBN} to create a special breakpoint (known as
2825 a @dfn{pending breakpoint}) that
2826 attempts to resolve itself in the future when an appropriate shared library
2829 Pending breakpoints are useful to set at the start of your
2830 @value{GDBN} session for locations that you know will be dynamically loaded
2831 later by the program being debugged. When shared libraries are loaded,
2832 a check is made to see if the load resolves any pending breakpoint locations.
2833 If a pending breakpoint location gets resolved,
2834 a regular breakpoint is created and the original pending breakpoint is removed.
2836 @value{GDBN} provides some additional commands for controlling pending
2839 @kindex set breakpoint pending
2840 @kindex show breakpoint pending
2842 @item set breakpoint pending auto
2843 This is the default behavior. When @value{GDBN} cannot find the breakpoint
2844 location, it queries you whether a pending breakpoint should be created.
2846 @item set breakpoint pending on
2847 This indicates that an unrecognized breakpoint location should automatically
2848 result in a pending breakpoint being created.
2850 @item set breakpoint pending off
2851 This indicates that pending breakpoints are not to be created. Any
2852 unrecognized breakpoint location results in an error. This setting does
2853 not affect any pending breakpoints previously created.
2855 @item show breakpoint pending
2856 Show the current behavior setting for creating pending breakpoints.
2859 @cindex operations allowed on pending breakpoints
2860 Normal breakpoint operations apply to pending breakpoints as well. You may
2861 specify a condition for a pending breakpoint and/or commands to run when the
2862 breakpoint is reached. You can also enable or disable
2863 the pending breakpoint. When you specify a condition for a pending breakpoint,
2864 the parsing of the condition will be deferred until the point where the
2865 pending breakpoint location is resolved. Disabling a pending breakpoint
2866 tells @value{GDBN} to not attempt to resolve the breakpoint on any subsequent
2867 shared library load. When a pending breakpoint is re-enabled,
2868 @value{GDBN} checks to see if the location is already resolved.
2869 This is done because any number of shared library loads could have
2870 occurred since the time the breakpoint was disabled and one or more
2871 of these loads could resolve the location.
2873 @cindex negative breakpoint numbers
2874 @cindex internal @value{GDBN} breakpoints
2875 @value{GDBN} itself sometimes sets breakpoints in your program for
2876 special purposes, such as proper handling of @code{longjmp} (in C
2877 programs). These internal breakpoints are assigned negative numbers,
2878 starting with @code{-1}; @samp{info breakpoints} does not display them.
2879 You can see these breakpoints with the @value{GDBN} maintenance command
2880 @samp{maint info breakpoints} (@pxref{maint info breakpoints}).
2883 @node Set Watchpoints
2884 @subsection Setting watchpoints
2886 @cindex setting watchpoints
2887 You can use a watchpoint to stop execution whenever the value of an
2888 expression changes, without having to predict a particular place where
2891 @cindex software watchpoints
2892 @cindex hardware watchpoints
2893 Depending on your system, watchpoints may be implemented in software or
2894 hardware. @value{GDBN} does software watchpointing by single-stepping your
2895 program and testing the variable's value each time, which is hundreds of
2896 times slower than normal execution. (But this may still be worth it, to
2897 catch errors where you have no clue what part of your program is the
2900 On some systems, such as HP-UX, @sc{gnu}/Linux and most other
2901 x86-based targets, @value{GDBN} includes support for hardware
2902 watchpoints, which do not slow down the running of your program.
2906 @item watch @var{expr}
2907 Set a watchpoint for an expression. @value{GDBN} will break when @var{expr}
2908 is written into by the program and its value changes.
2911 @item rwatch @var{expr}
2912 Set a watchpoint that will break when the value of @var{expr} is read
2916 @item awatch @var{expr}
2917 Set a watchpoint that will break when @var{expr} is either read from
2918 or written into by the program.
2920 @kindex info watchpoints
2921 @item info watchpoints
2922 This command prints a list of watchpoints, breakpoints, and catchpoints;
2923 it is the same as @code{info break} (@pxref{Set Breaks}).
2926 @value{GDBN} sets a @dfn{hardware watchpoint} if possible. Hardware
2927 watchpoints execute very quickly, and the debugger reports a change in
2928 value at the exact instruction where the change occurs. If @value{GDBN}
2929 cannot set a hardware watchpoint, it sets a software watchpoint, which
2930 executes more slowly and reports the change in value at the next
2931 @emph{statement}, not the instruction, after the change occurs.
2933 @cindex use only software watchpoints
2934 You can force @value{GDBN} to use only software watchpoints with the
2935 @kbd{set can-use-hw-watchpoints 0} command. With this variable set to
2936 zero, @value{GDBN} will never try to use hardware watchpoints, even if
2937 the underlying system supports them. (Note that hardware-assisted
2938 watchpoints that were set @emph{before} setting
2939 @code{can-use-hw-watchpoints} to zero will still use the hardware
2940 mechanism of watching expressiion values.)
2943 @item set can-use-hw-watchpoints
2944 @kindex set can-use-hw-watchpoints
2945 Set whether or not to use hardware watchpoints.
2947 @item show can-use-hw-watchpoints
2948 @kindex show can-use-hw-watchpoints
2949 Show the current mode of using hardware watchpoints.
2952 For remote targets, you can restrict the number of hardware
2953 watchpoints @value{GDBN} will use, see @ref{set remote
2954 hardware-breakpoint-limit}.
2956 When you issue the @code{watch} command, @value{GDBN} reports
2959 Hardware watchpoint @var{num}: @var{expr}
2963 if it was able to set a hardware watchpoint.
2965 Currently, the @code{awatch} and @code{rwatch} commands can only set
2966 hardware watchpoints, because accesses to data that don't change the
2967 value of the watched expression cannot be detected without examining
2968 every instruction as it is being executed, and @value{GDBN} does not do
2969 that currently. If @value{GDBN} finds that it is unable to set a
2970 hardware breakpoint with the @code{awatch} or @code{rwatch} command, it
2971 will print a message like this:
2974 Expression cannot be implemented with read/access watchpoint.
2977 Sometimes, @value{GDBN} cannot set a hardware watchpoint because the
2978 data type of the watched expression is wider than what a hardware
2979 watchpoint on the target machine can handle. For example, some systems
2980 can only watch regions that are up to 4 bytes wide; on such systems you
2981 cannot set hardware watchpoints for an expression that yields a
2982 double-precision floating-point number (which is typically 8 bytes
2983 wide). As a work-around, it might be possible to break the large region
2984 into a series of smaller ones and watch them with separate watchpoints.
2986 If you set too many hardware watchpoints, @value{GDBN} might be unable
2987 to insert all of them when you resume the execution of your program.
2988 Since the precise number of active watchpoints is unknown until such
2989 time as the program is about to be resumed, @value{GDBN} might not be
2990 able to warn you about this when you set the watchpoints, and the
2991 warning will be printed only when the program is resumed:
2994 Hardware watchpoint @var{num}: Could not insert watchpoint
2998 If this happens, delete or disable some of the watchpoints.
3000 The SPARClite DSU will generate traps when a program accesses some data
3001 or instruction address that is assigned to the debug registers. For the
3002 data addresses, DSU facilitates the @code{watch} command. However the
3003 hardware breakpoint registers can only take two data watchpoints, and
3004 both watchpoints must be the same kind. For example, you can set two
3005 watchpoints with @code{watch} commands, two with @code{rwatch} commands,
3006 @strong{or} two with @code{awatch} commands, but you cannot set one
3007 watchpoint with one command and the other with a different command.
3008 @value{GDBN} will reject the command if you try to mix watchpoints.
3009 Delete or disable unused watchpoint commands before setting new ones.
3011 If you call a function interactively using @code{print} or @code{call},
3012 any watchpoints you have set will be inactive until @value{GDBN} reaches another
3013 kind of breakpoint or the call completes.
3015 @value{GDBN} automatically deletes watchpoints that watch local
3016 (automatic) variables, or expressions that involve such variables, when
3017 they go out of scope, that is, when the execution leaves the block in
3018 which these variables were defined. In particular, when the program
3019 being debugged terminates, @emph{all} local variables go out of scope,
3020 and so only watchpoints that watch global variables remain set. If you
3021 rerun the program, you will need to set all such watchpoints again. One
3022 way of doing that would be to set a code breakpoint at the entry to the
3023 @code{main} function and when it breaks, set all the watchpoints.
3026 @cindex watchpoints and threads
3027 @cindex threads and watchpoints
3028 @emph{Warning:} In multi-thread programs, watchpoints have only limited
3029 usefulness. With the current watchpoint implementation, @value{GDBN}
3030 can only watch the value of an expression @emph{in a single thread}. If
3031 you are confident that the expression can only change due to the current
3032 thread's activity (and if you are also confident that no other thread
3033 can become current), then you can use watchpoints as usual. However,
3034 @value{GDBN} may not notice when a non-current thread's activity changes
3037 @c FIXME: this is almost identical to the previous paragraph.
3038 @emph{HP-UX Warning:} In multi-thread programs, software watchpoints
3039 have only limited usefulness. If @value{GDBN} creates a software
3040 watchpoint, it can only watch the value of an expression @emph{in a
3041 single thread}. If you are confident that the expression can only
3042 change due to the current thread's activity (and if you are also
3043 confident that no other thread can become current), then you can use
3044 software watchpoints as usual. However, @value{GDBN} may not notice
3045 when a non-current thread's activity changes the expression. (Hardware
3046 watchpoints, in contrast, watch an expression in all threads.)
3049 @xref{set remote hardware-watchpoint-limit}.
3051 @node Set Catchpoints
3052 @subsection Setting catchpoints
3053 @cindex catchpoints, setting
3054 @cindex exception handlers
3055 @cindex event handling
3057 You can use @dfn{catchpoints} to cause the debugger to stop for certain
3058 kinds of program events, such as C@t{++} exceptions or the loading of a
3059 shared library. Use the @code{catch} command to set a catchpoint.
3063 @item catch @var{event}
3064 Stop when @var{event} occurs. @var{event} can be any of the following:
3067 @cindex stop on C@t{++} exceptions
3068 The throwing of a C@t{++} exception.
3071 The catching of a C@t{++} exception.
3074 @cindex break on fork/exec
3075 A call to @code{exec}. This is currently only available for HP-UX.
3078 A call to @code{fork}. This is currently only available for HP-UX.
3081 A call to @code{vfork}. This is currently only available for HP-UX.
3084 @itemx load @var{libname}
3085 @cindex break on load/unload of shared library
3086 The dynamic loading of any shared library, or the loading of the library
3087 @var{libname}. This is currently only available for HP-UX.
3090 @itemx unload @var{libname}
3091 The unloading of any dynamically loaded shared library, or the unloading
3092 of the library @var{libname}. This is currently only available for HP-UX.
3095 @item tcatch @var{event}
3096 Set a catchpoint that is enabled only for one stop. The catchpoint is
3097 automatically deleted after the first time the event is caught.
3101 Use the @code{info break} command to list the current catchpoints.
3103 There are currently some limitations to C@t{++} exception handling
3104 (@code{catch throw} and @code{catch catch}) in @value{GDBN}:
3108 If you call a function interactively, @value{GDBN} normally returns
3109 control to you when the function has finished executing. If the call
3110 raises an exception, however, the call may bypass the mechanism that
3111 returns control to you and cause your program either to abort or to
3112 simply continue running until it hits a breakpoint, catches a signal
3113 that @value{GDBN} is listening for, or exits. This is the case even if
3114 you set a catchpoint for the exception; catchpoints on exceptions are
3115 disabled within interactive calls.
3118 You cannot raise an exception interactively.
3121 You cannot install an exception handler interactively.
3124 @cindex raise exceptions
3125 Sometimes @code{catch} is not the best way to debug exception handling:
3126 if you need to know exactly where an exception is raised, it is better to
3127 stop @emph{before} the exception handler is called, since that way you
3128 can see the stack before any unwinding takes place. If you set a
3129 breakpoint in an exception handler instead, it may not be easy to find
3130 out where the exception was raised.
3132 To stop just before an exception handler is called, you need some
3133 knowledge of the implementation. In the case of @sc{gnu} C@t{++}, exceptions are
3134 raised by calling a library function named @code{__raise_exception}
3135 which has the following ANSI C interface:
3138 /* @var{addr} is where the exception identifier is stored.
3139 @var{id} is the exception identifier. */
3140 void __raise_exception (void **addr, void *id);
3144 To make the debugger catch all exceptions before any stack
3145 unwinding takes place, set a breakpoint on @code{__raise_exception}
3146 (@pxref{Breakpoints, ,Breakpoints; watchpoints; and exceptions}).
3148 With a conditional breakpoint (@pxref{Conditions, ,Break conditions})
3149 that depends on the value of @var{id}, you can stop your program when
3150 a specific exception is raised. You can use multiple conditional
3151 breakpoints to stop your program when any of a number of exceptions are
3156 @subsection Deleting breakpoints
3158 @cindex clearing breakpoints, watchpoints, catchpoints
3159 @cindex deleting breakpoints, watchpoints, catchpoints
3160 It is often necessary to eliminate a breakpoint, watchpoint, or
3161 catchpoint once it has done its job and you no longer want your program
3162 to stop there. This is called @dfn{deleting} the breakpoint. A
3163 breakpoint that has been deleted no longer exists; it is forgotten.
3165 With the @code{clear} command you can delete breakpoints according to
3166 where they are in your program. With the @code{delete} command you can
3167 delete individual breakpoints, watchpoints, or catchpoints by specifying
3168 their breakpoint numbers.
3170 It is not necessary to delete a breakpoint to proceed past it. @value{GDBN}
3171 automatically ignores breakpoints on the first instruction to be executed
3172 when you continue execution without changing the execution address.
3177 Delete any breakpoints at the next instruction to be executed in the
3178 selected stack frame (@pxref{Selection, ,Selecting a frame}). When
3179 the innermost frame is selected, this is a good way to delete a
3180 breakpoint where your program just stopped.
3182 @item clear @var{function}
3183 @itemx clear @var{filename}:@var{function}
3184 Delete any breakpoints set at entry to the named @var{function}.
3186 @item clear @var{linenum}
3187 @itemx clear @var{filename}:@var{linenum}
3188 Delete any breakpoints set at or within the code of the specified
3189 @var{linenum} of the specified @var{filename}.
3191 @cindex delete breakpoints
3193 @kindex d @r{(@code{delete})}
3194 @item delete @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]}
3195 Delete the breakpoints, watchpoints, or catchpoints of the breakpoint
3196 ranges specified as arguments. If no argument is specified, delete all
3197 breakpoints (@value{GDBN} asks confirmation, unless you have @code{set
3198 confirm off}). You can abbreviate this command as @code{d}.
3202 @subsection Disabling breakpoints
3204 @cindex enable/disable a breakpoint
3205 Rather than deleting a breakpoint, watchpoint, or catchpoint, you might
3206 prefer to @dfn{disable} it. This makes the breakpoint inoperative as if
3207 it had been deleted, but remembers the information on the breakpoint so
3208 that you can @dfn{enable} it again later.
3210 You disable and enable breakpoints, watchpoints, and catchpoints with
3211 the @code{enable} and @code{disable} commands, optionally specifying one
3212 or more breakpoint numbers as arguments. Use @code{info break} or
3213 @code{info watch} to print a list of breakpoints, watchpoints, and
3214 catchpoints if you do not know which numbers to use.
3216 A breakpoint, watchpoint, or catchpoint can have any of four different
3217 states of enablement:
3221 Enabled. The breakpoint stops your program. A breakpoint set
3222 with the @code{break} command starts out in this state.
3224 Disabled. The breakpoint has no effect on your program.
3226 Enabled once. The breakpoint stops your program, but then becomes
3229 Enabled for deletion. The breakpoint stops your program, but
3230 immediately after it does so it is deleted permanently. A breakpoint
3231 set with the @code{tbreak} command starts out in this state.
3234 You can use the following commands to enable or disable breakpoints,
3235 watchpoints, and catchpoints:
3239 @kindex dis @r{(@code{disable})}
3240 @item disable @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]}
3241 Disable the specified breakpoints---or all breakpoints, if none are
3242 listed. A disabled breakpoint has no effect but is not forgotten. All
3243 options such as ignore-counts, conditions and commands are remembered in
3244 case the breakpoint is enabled again later. You may abbreviate
3245 @code{disable} as @code{dis}.
3248 @item enable @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]}
3249 Enable the specified breakpoints (or all defined breakpoints). They
3250 become effective once again in stopping your program.
3252 @item enable @r{[}breakpoints@r{]} once @var{range}@dots{}
3253 Enable the specified breakpoints temporarily. @value{GDBN} disables any
3254 of these breakpoints immediately after stopping your program.
3256 @item enable @r{[}breakpoints@r{]} delete @var{range}@dots{}
3257 Enable the specified breakpoints to work once, then die. @value{GDBN}
3258 deletes any of these breakpoints as soon as your program stops there.
3259 Breakpoints set by the @code{tbreak} command start out in this state.
3262 @c FIXME: I think the following ``Except for [...] @code{tbreak}'' is
3263 @c confusing: tbreak is also initially enabled.
3264 Except for a breakpoint set with @code{tbreak} (@pxref{Set Breaks,
3265 ,Setting breakpoints}), breakpoints that you set are initially enabled;
3266 subsequently, they become disabled or enabled only when you use one of
3267 the commands above. (The command @code{until} can set and delete a
3268 breakpoint of its own, but it does not change the state of your other
3269 breakpoints; see @ref{Continuing and Stepping, ,Continuing and
3273 @subsection Break conditions
3274 @cindex conditional breakpoints
3275 @cindex breakpoint conditions
3277 @c FIXME what is scope of break condition expr? Context where wanted?
3278 @c in particular for a watchpoint?
3279 The simplest sort of breakpoint breaks every time your program reaches a
3280 specified place. You can also specify a @dfn{condition} for a
3281 breakpoint. A condition is just a Boolean expression in your
3282 programming language (@pxref{Expressions, ,Expressions}). A breakpoint with
3283 a condition evaluates the expression each time your program reaches it,
3284 and your program stops only if the condition is @emph{true}.
3286 This is the converse of using assertions for program validation; in that
3287 situation, you want to stop when the assertion is violated---that is,
3288 when the condition is false. In C, if you want to test an assertion expressed
3289 by the condition @var{assert}, you should set the condition
3290 @samp{! @var{assert}} on the appropriate breakpoint.
3292 Conditions are also accepted for watchpoints; you may not need them,
3293 since a watchpoint is inspecting the value of an expression anyhow---but
3294 it might be simpler, say, to just set a watchpoint on a variable name,
3295 and specify a condition that tests whether the new value is an interesting
3298 Break conditions can have side effects, and may even call functions in
3299 your program. This can be useful, for example, to activate functions
3300 that log program progress, or to use your own print functions to
3301 format special data structures. The effects are completely predictable
3302 unless there is another enabled breakpoint at the same address. (In
3303 that case, @value{GDBN} might see the other breakpoint first and stop your
3304 program without checking the condition of this one.) Note that
3305 breakpoint commands are usually more convenient and flexible than break
3307 purpose of performing side effects when a breakpoint is reached
3308 (@pxref{Break Commands, ,Breakpoint command lists}).
3310 Break conditions can be specified when a breakpoint is set, by using
3311 @samp{if} in the arguments to the @code{break} command. @xref{Set
3312 Breaks, ,Setting breakpoints}. They can also be changed at any time
3313 with the @code{condition} command.
3315 You can also use the @code{if} keyword with the @code{watch} command.
3316 The @code{catch} command does not recognize the @code{if} keyword;
3317 @code{condition} is the only way to impose a further condition on a
3322 @item condition @var{bnum} @var{expression}
3323 Specify @var{expression} as the break condition for breakpoint,
3324 watchpoint, or catchpoint number @var{bnum}. After you set a condition,
3325 breakpoint @var{bnum} stops your program only if the value of
3326 @var{expression} is true (nonzero, in C). When you use
3327 @code{condition}, @value{GDBN} checks @var{expression} immediately for
3328 syntactic correctness, and to determine whether symbols in it have
3329 referents in the context of your breakpoint. If @var{expression} uses
3330 symbols not referenced in the context of the breakpoint, @value{GDBN}
3331 prints an error message:
3334 No symbol "foo" in current context.
3339 not actually evaluate @var{expression} at the time the @code{condition}
3340 command (or a command that sets a breakpoint with a condition, like
3341 @code{break if @dots{}}) is given, however. @xref{Expressions, ,Expressions}.
3343 @item condition @var{bnum}
3344 Remove the condition from breakpoint number @var{bnum}. It becomes
3345 an ordinary unconditional breakpoint.
3348 @cindex ignore count (of breakpoint)
3349 A special case of a breakpoint condition is to stop only when the
3350 breakpoint has been reached a certain number of times. This is so
3351 useful that there is a special way to do it, using the @dfn{ignore
3352 count} of the breakpoint. Every breakpoint has an ignore count, which
3353 is an integer. Most of the time, the ignore count is zero, and
3354 therefore has no effect. But if your program reaches a breakpoint whose
3355 ignore count is positive, then instead of stopping, it just decrements
3356 the ignore count by one and continues. As a result, if the ignore count
3357 value is @var{n}, the breakpoint does not stop the next @var{n} times
3358 your program reaches it.
3362 @item ignore @var{bnum} @var{count}
3363 Set the ignore count of breakpoint number @var{bnum} to @var{count}.
3364 The next @var{count} times the breakpoint is reached, your program's
3365 execution does not stop; other than to decrement the ignore count, @value{GDBN}
3368 To make the breakpoint stop the next time it is reached, specify
3371 When you use @code{continue} to resume execution of your program from a
3372 breakpoint, you can specify an ignore count directly as an argument to
3373 @code{continue}, rather than using @code{ignore}. @xref{Continuing and
3374 Stepping,,Continuing and stepping}.
3376 If a breakpoint has a positive ignore count and a condition, the
3377 condition is not checked. Once the ignore count reaches zero,
3378 @value{GDBN} resumes checking the condition.
3380 You could achieve the effect of the ignore count with a condition such
3381 as @w{@samp{$foo-- <= 0}} using a debugger convenience variable that
3382 is decremented each time. @xref{Convenience Vars, ,Convenience
3386 Ignore counts apply to breakpoints, watchpoints, and catchpoints.
3389 @node Break Commands
3390 @subsection Breakpoint command lists
3392 @cindex breakpoint commands
3393 You can give any breakpoint (or watchpoint or catchpoint) a series of
3394 commands to execute when your program stops due to that breakpoint. For
3395 example, you might want to print the values of certain expressions, or
3396 enable other breakpoints.
3401 @item commands @r{[}@var{bnum}@r{]}
3402 @itemx @dots{} @var{command-list} @dots{}
3404 Specify a list of commands for breakpoint number @var{bnum}. The commands
3405 themselves appear on the following lines. Type a line containing just
3406 @code{end} to terminate the commands.
3408 To remove all commands from a breakpoint, type @code{commands} and
3409 follow it immediately with @code{end}; that is, give no commands.
3411 With no @var{bnum} argument, @code{commands} refers to the last
3412 breakpoint, watchpoint, or catchpoint set (not to the breakpoint most
3413 recently encountered).
3416 Pressing @key{RET} as a means of repeating the last @value{GDBN} command is
3417 disabled within a @var{command-list}.
3419 You can use breakpoint commands to start your program up again. Simply
3420 use the @code{continue} command, or @code{step}, or any other command
3421 that resumes execution.
3423 Any other commands in the command list, after a command that resumes
3424 execution, are ignored. This is because any time you resume execution
3425 (even with a simple @code{next} or @code{step}), you may encounter
3426 another breakpoint---which could have its own command list, leading to
3427 ambiguities about which list to execute.
3430 If the first command you specify in a command list is @code{silent}, the
3431 usual message about stopping at a breakpoint is not printed. This may
3432 be desirable for breakpoints that are to print a specific message and
3433 then continue. If none of the remaining commands print anything, you
3434 see no sign that the breakpoint was reached. @code{silent} is
3435 meaningful only at the beginning of a breakpoint command list.
3437 The commands @code{echo}, @code{output}, and @code{printf} allow you to
3438 print precisely controlled output, and are often useful in silent
3439 breakpoints. @xref{Output, ,Commands for controlled output}.
3441 For example, here is how you could use breakpoint commands to print the
3442 value of @code{x} at entry to @code{foo} whenever @code{x} is positive.
3448 printf "x is %d\n",x
3453 One application for breakpoint commands is to compensate for one bug so
3454 you can test for another. Put a breakpoint just after the erroneous line
3455 of code, give it a condition to detect the case in which something
3456 erroneous has been done, and give it commands to assign correct values
3457 to any variables that need them. End with the @code{continue} command
3458 so that your program does not stop, and start with the @code{silent}
3459 command so that no output is produced. Here is an example:
3470 @node Breakpoint Menus
3471 @subsection Breakpoint menus
3473 @cindex symbol overloading
3475 Some programming languages (notably C@t{++} and Objective-C) permit a
3476 single function name
3477 to be defined several times, for application in different contexts.
3478 This is called @dfn{overloading}. When a function name is overloaded,
3479 @samp{break @var{function}} is not enough to tell @value{GDBN} where you want
3480 a breakpoint. If you realize this is a problem, you can use
3481 something like @samp{break @var{function}(@var{types})} to specify which
3482 particular version of the function you want. Otherwise, @value{GDBN} offers
3483 you a menu of numbered choices for different possible breakpoints, and
3484 waits for your selection with the prompt @samp{>}. The first two
3485 options are always @samp{[0] cancel} and @samp{[1] all}. Typing @kbd{1}
3486 sets a breakpoint at each definition of @var{function}, and typing
3487 @kbd{0} aborts the @code{break} command without setting any new
3490 For example, the following session excerpt shows an attempt to set a
3491 breakpoint at the overloaded symbol @code{String::after}.
3492 We choose three particular definitions of that function name:
3494 @c FIXME! This is likely to change to show arg type lists, at least
3497 (@value{GDBP}) b String::after
3500 [2] file:String.cc; line number:867
3501 [3] file:String.cc; line number:860
3502 [4] file:String.cc; line number:875
3503 [5] file:String.cc; line number:853
3504 [6] file:String.cc; line number:846
3505 [7] file:String.cc; line number:735
3507 Breakpoint 1 at 0xb26c: file String.cc, line 867.
3508 Breakpoint 2 at 0xb344: file String.cc, line 875.
3509 Breakpoint 3 at 0xafcc: file String.cc, line 846.
3510 Multiple breakpoints were set.
3511 Use the "delete" command to delete unwanted
3517 @c @ifclear BARETARGET
3518 @node Error in Breakpoints
3519 @subsection ``Cannot insert breakpoints''
3521 @c FIXME!! 14/6/95 Is there a real example of this? Let's use it.
3523 Under some operating systems, breakpoints cannot be used in a program if
3524 any other process is running that program. In this situation,
3525 attempting to run or continue a program with a breakpoint causes
3526 @value{GDBN} to print an error message:
3529 Cannot insert breakpoints.
3530 The same program may be running in another process.
3533 When this happens, you have three ways to proceed:
3537 Remove or disable the breakpoints, then continue.
3540 Suspend @value{GDBN}, and copy the file containing your program to a new
3541 name. Resume @value{GDBN} and use the @code{exec-file} command to specify
3542 that @value{GDBN} should run your program under that name.
3543 Then start your program again.
3546 Relink your program so that the text segment is nonsharable, using the
3547 linker option @samp{-N}. The operating system limitation may not apply
3548 to nonsharable executables.
3552 A similar message can be printed if you request too many active
3553 hardware-assisted breakpoints and watchpoints:
3555 @c FIXME: the precise wording of this message may change; the relevant
3556 @c source change is not committed yet (Sep 3, 1999).
3558 Stopped; cannot insert breakpoints.
3559 You may have requested too many hardware breakpoints and watchpoints.
3563 This message is printed when you attempt to resume the program, since
3564 only then @value{GDBN} knows exactly how many hardware breakpoints and
3565 watchpoints it needs to insert.
3567 When this message is printed, you need to disable or remove some of the
3568 hardware-assisted breakpoints and watchpoints, and then continue.
3570 @node Breakpoint related warnings
3571 @subsection ``Breakpoint address adjusted...''
3572 @cindex breakpoint address adjusted
3574 Some processor architectures place constraints on the addresses at
3575 which breakpoints may be placed. For architectures thus constrained,
3576 @value{GDBN} will attempt to adjust the breakpoint's address to comply
3577 with the constraints dictated by the architecture.
3579 One example of such an architecture is the Fujitsu FR-V. The FR-V is
3580 a VLIW architecture in which a number of RISC-like instructions may be
3581 bundled together for parallel execution. The FR-V architecture
3582 constrains the location of a breakpoint instruction within such a
3583 bundle to the instruction with the lowest address. @value{GDBN}
3584 honors this constraint by adjusting a breakpoint's address to the
3585 first in the bundle.
3587 It is not uncommon for optimized code to have bundles which contain
3588 instructions from different source statements, thus it may happen that
3589 a breakpoint's address will be adjusted from one source statement to
3590 another. Since this adjustment may significantly alter @value{GDBN}'s
3591 breakpoint related behavior from what the user expects, a warning is
3592 printed when the breakpoint is first set and also when the breakpoint
3595 A warning like the one below is printed when setting a breakpoint
3596 that's been subject to address adjustment:
3599 warning: Breakpoint address adjusted from 0x00010414 to 0x00010410.
3602 Such warnings are printed both for user settable and @value{GDBN}'s
3603 internal breakpoints. If you see one of these warnings, you should
3604 verify that a breakpoint set at the adjusted address will have the
3605 desired affect. If not, the breakpoint in question may be removed and
3606 other breakpoints may be set which will have the desired behavior.
3607 E.g., it may be sufficient to place the breakpoint at a later
3608 instruction. A conditional breakpoint may also be useful in some
3609 cases to prevent the breakpoint from triggering too often.
3611 @value{GDBN} will also issue a warning when stopping at one of these
3612 adjusted breakpoints:
3615 warning: Breakpoint 1 address previously adjusted from 0x00010414
3619 When this warning is encountered, it may be too late to take remedial
3620 action except in cases where the breakpoint is hit earlier or more
3621 frequently than expected.
3623 @node Continuing and Stepping
3624 @section Continuing and stepping
3628 @cindex resuming execution
3629 @dfn{Continuing} means resuming program execution until your program
3630 completes normally. In contrast, @dfn{stepping} means executing just
3631 one more ``step'' of your program, where ``step'' may mean either one
3632 line of source code, or one machine instruction (depending on what
3633 particular command you use). Either when continuing or when stepping,
3634 your program may stop even sooner, due to a breakpoint or a signal. (If
3635 it stops due to a signal, you may want to use @code{handle}, or use
3636 @samp{signal 0} to resume execution. @xref{Signals, ,Signals}.)
3640 @kindex c @r{(@code{continue})}
3641 @kindex fg @r{(resume foreground execution)}
3642 @item continue @r{[}@var{ignore-count}@r{]}
3643 @itemx c @r{[}@var{ignore-count}@r{]}
3644 @itemx fg @r{[}@var{ignore-count}@r{]}
3645 Resume program execution, at the address where your program last stopped;
3646 any breakpoints set at that address are bypassed. The optional argument
3647 @var{ignore-count} allows you to specify a further number of times to
3648 ignore a breakpoint at this location; its effect is like that of
3649 @code{ignore} (@pxref{Conditions, ,Break conditions}).
3651 The argument @var{ignore-count} is meaningful only when your program
3652 stopped due to a breakpoint. At other times, the argument to
3653 @code{continue} is ignored.
3655 The synonyms @code{c} and @code{fg} (for @dfn{foreground}, as the
3656 debugged program is deemed to be the foreground program) are provided
3657 purely for convenience, and have exactly the same behavior as
3661 To resume execution at a different place, you can use @code{return}
3662 (@pxref{Returning, ,Returning from a function}) to go back to the
3663 calling function; or @code{jump} (@pxref{Jumping, ,Continuing at a
3664 different address}) to go to an arbitrary location in your program.
3666 A typical technique for using stepping is to set a breakpoint
3667 (@pxref{Breakpoints, ,Breakpoints; watchpoints; and catchpoints}) at the
3668 beginning of the function or the section of your program where a problem
3669 is believed to lie, run your program until it stops at that breakpoint,
3670 and then step through the suspect area, examining the variables that are
3671 interesting, until you see the problem happen.
3675 @kindex s @r{(@code{step})}
3677 Continue running your program until control reaches a different source
3678 line, then stop it and return control to @value{GDBN}. This command is
3679 abbreviated @code{s}.
3682 @c "without debugging information" is imprecise; actually "without line
3683 @c numbers in the debugging information". (gcc -g1 has debugging info but
3684 @c not line numbers). But it seems complex to try to make that
3685 @c distinction here.
3686 @emph{Warning:} If you use the @code{step} command while control is
3687 within a function that was compiled without debugging information,
3688 execution proceeds until control reaches a function that does have
3689 debugging information. Likewise, it will not step into a function which
3690 is compiled without debugging information. To step through functions
3691 without debugging information, use the @code{stepi} command, described
3695 The @code{step} command only stops at the first instruction of a source
3696 line. This prevents the multiple stops that could otherwise occur in
3697 @code{switch} statements, @code{for} loops, etc. @code{step} continues
3698 to stop if a function that has debugging information is called within
3699 the line. In other words, @code{step} @emph{steps inside} any functions
3700 called within the line.
3702 Also, the @code{step} command only enters a function if there is line
3703 number information for the function. Otherwise it acts like the
3704 @code{next} command. This avoids problems when using @code{cc -gl}
3705 on MIPS machines. Previously, @code{step} entered subroutines if there
3706 was any debugging information about the routine.
3708 @item step @var{count}
3709 Continue running as in @code{step}, but do so @var{count} times. If a
3710 breakpoint is reached, or a signal not related to stepping occurs before
3711 @var{count} steps, stepping stops right away.
3714 @kindex n @r{(@code{next})}
3715 @item next @r{[}@var{count}@r{]}
3716 Continue to the next source line in the current (innermost) stack frame.
3717 This is similar to @code{step}, but function calls that appear within
3718 the line of code are executed without stopping. Execution stops when
3719 control reaches a different line of code at the original stack level
3720 that was executing when you gave the @code{next} command. This command
3721 is abbreviated @code{n}.
3723 An argument @var{count} is a repeat count, as for @code{step}.
3726 @c FIX ME!! Do we delete this, or is there a way it fits in with
3727 @c the following paragraph? --- Vctoria
3729 @c @code{next} within a function that lacks debugging information acts like
3730 @c @code{step}, but any function calls appearing within the code of the
3731 @c function are executed without stopping.
3733 The @code{next} command only stops at the first instruction of a
3734 source line. This prevents multiple stops that could otherwise occur in
3735 @code{switch} statements, @code{for} loops, etc.
3737 @kindex set step-mode
3739 @cindex functions without line info, and stepping
3740 @cindex stepping into functions with no line info
3741 @itemx set step-mode on
3742 The @code{set step-mode on} command causes the @code{step} command to
3743 stop at the first instruction of a function which contains no debug line
3744 information rather than stepping over it.
3746 This is useful in cases where you may be interested in inspecting the
3747 machine instructions of a function which has no symbolic info and do not
3748 want @value{GDBN} to automatically skip over this function.
3750 @item set step-mode off
3751 Causes the @code{step} command to step over any functions which contains no
3752 debug information. This is the default.
3754 @item show step-mode
3755 Show whether @value{GDBN} will stop in or step over functions without
3756 source line debug information.
3760 Continue running until just after function in the selected stack frame
3761 returns. Print the returned value (if any).
3763 Contrast this with the @code{return} command (@pxref{Returning,
3764 ,Returning from a function}).
3767 @kindex u @r{(@code{until})}
3768 @cindex run until specified location
3771 Continue running until a source line past the current line, in the
3772 current stack frame, is reached. This command is used to avoid single
3773 stepping through a loop more than once. It is like the @code{next}
3774 command, except that when @code{until} encounters a jump, it
3775 automatically continues execution until the program counter is greater
3776 than the address of the jump.
3778 This means that when you reach the end of a loop after single stepping
3779 though it, @code{until} makes your program continue execution until it
3780 exits the loop. In contrast, a @code{next} command at the end of a loop
3781 simply steps back to the beginning of the loop, which forces you to step
3782 through the next iteration.
3784 @code{until} always stops your program if it attempts to exit the current
3787 @code{until} may produce somewhat counterintuitive results if the order
3788 of machine code does not match the order of the source lines. For
3789 example, in the following excerpt from a debugging session, the @code{f}
3790 (@code{frame}) command shows that execution is stopped at line
3791 @code{206}; yet when we use @code{until}, we get to line @code{195}:
3795 #0 main (argc=4, argv=0xf7fffae8) at m4.c:206
3797 (@value{GDBP}) until
3798 195 for ( ; argc > 0; NEXTARG) @{
3801 This happened because, for execution efficiency, the compiler had
3802 generated code for the loop closure test at the end, rather than the
3803 start, of the loop---even though the test in a C @code{for}-loop is
3804 written before the body of the loop. The @code{until} command appeared
3805 to step back to the beginning of the loop when it advanced to this
3806 expression; however, it has not really gone to an earlier
3807 statement---not in terms of the actual machine code.
3809 @code{until} with no argument works by means of single
3810 instruction stepping, and hence is slower than @code{until} with an
3813 @item until @var{location}
3814 @itemx u @var{location}
3815 Continue running your program until either the specified location is
3816 reached, or the current stack frame returns. @var{location} is any of
3817 the forms of argument acceptable to @code{break} (@pxref{Set Breaks,
3818 ,Setting breakpoints}). This form of the command uses breakpoints, and
3819 hence is quicker than @code{until} without an argument. The specified
3820 location is actually reached only if it is in the current frame. This
3821 implies that @code{until} can be used to skip over recursive function
3822 invocations. For instance in the code below, if the current location is
3823 line @code{96}, issuing @code{until 99} will execute the program up to
3824 line @code{99} in the same invocation of factorial, i.e. after the inner
3825 invocations have returned.
3828 94 int factorial (int value)
3830 96 if (value > 1) @{
3831 97 value *= factorial (value - 1);
3838 @kindex advance @var{location}
3839 @itemx advance @var{location}
3840 Continue running the program up to the given @var{location}. An argument is
3841 required, which should be of the same form as arguments for the @code{break}
3842 command. Execution will also stop upon exit from the current stack
3843 frame. This command is similar to @code{until}, but @code{advance} will
3844 not skip over recursive function calls, and the target location doesn't
3845 have to be in the same frame as the current one.
3849 @kindex si @r{(@code{stepi})}
3851 @itemx stepi @var{arg}
3853 Execute one machine instruction, then stop and return to the debugger.
3855 It is often useful to do @samp{display/i $pc} when stepping by machine
3856 instructions. This makes @value{GDBN} automatically display the next
3857 instruction to be executed, each time your program stops. @xref{Auto
3858 Display,, Automatic display}.
3860 An argument is a repeat count, as in @code{step}.
3864 @kindex ni @r{(@code{nexti})}
3866 @itemx nexti @var{arg}
3868 Execute one machine instruction, but if it is a function call,
3869 proceed until the function returns.
3871 An argument is a repeat count, as in @code{next}.
3878 A signal is an asynchronous event that can happen in a program. The
3879 operating system defines the possible kinds of signals, and gives each
3880 kind a name and a number. For example, in Unix @code{SIGINT} is the
3881 signal a program gets when you type an interrupt character (often @kbd{C-c});
3882 @code{SIGSEGV} is the signal a program gets from referencing a place in
3883 memory far away from all the areas in use; @code{SIGALRM} occurs when
3884 the alarm clock timer goes off (which happens only if your program has
3885 requested an alarm).
3887 @cindex fatal signals
3888 Some signals, including @code{SIGALRM}, are a normal part of the
3889 functioning of your program. Others, such as @code{SIGSEGV}, indicate
3890 errors; these signals are @dfn{fatal} (they kill your program immediately) if the
3891 program has not specified in advance some other way to handle the signal.
3892 @code{SIGINT} does not indicate an error in your program, but it is normally
3893 fatal so it can carry out the purpose of the interrupt: to kill the program.
3895 @value{GDBN} has the ability to detect any occurrence of a signal in your
3896 program. You can tell @value{GDBN} in advance what to do for each kind of
3899 @cindex handling signals
3900 Normally, @value{GDBN} is set up to let the non-erroneous signals like
3901 @code{SIGALRM} be silently passed to your program
3902 (so as not to interfere with their role in the program's functioning)
3903 but to stop your program immediately whenever an error signal happens.
3904 You can change these settings with the @code{handle} command.
3907 @kindex info signals
3911 Print a table of all the kinds of signals and how @value{GDBN} has been told to
3912 handle each one. You can use this to see the signal numbers of all
3913 the defined types of signals.
3915 @code{info handle} is an alias for @code{info signals}.
3918 @item handle @var{signal} @var{keywords}@dots{}
3919 Change the way @value{GDBN} handles signal @var{signal}. @var{signal}
3920 can be the number of a signal or its name (with or without the
3921 @samp{SIG} at the beginning); a list of signal numbers of the form
3922 @samp{@var{low}-@var{high}}; or the word @samp{all}, meaning all the
3923 known signals. The @var{keywords} say what change to make.
3927 The keywords allowed by the @code{handle} command can be abbreviated.
3928 Their full names are:
3932 @value{GDBN} should not stop your program when this signal happens. It may
3933 still print a message telling you that the signal has come in.
3936 @value{GDBN} should stop your program when this signal happens. This implies
3937 the @code{print} keyword as well.
3940 @value{GDBN} should print a message when this signal happens.
3943 @value{GDBN} should not mention the occurrence of the signal at all. This
3944 implies the @code{nostop} keyword as well.
3948 @value{GDBN} should allow your program to see this signal; your program
3949 can handle the signal, or else it may terminate if the signal is fatal
3950 and not handled. @code{pass} and @code{noignore} are synonyms.
3954 @value{GDBN} should not allow your program to see this signal.
3955 @code{nopass} and @code{ignore} are synonyms.
3959 When a signal stops your program, the signal is not visible to the
3961 continue. Your program sees the signal then, if @code{pass} is in
3962 effect for the signal in question @emph{at that time}. In other words,
3963 after @value{GDBN} reports a signal, you can use the @code{handle}
3964 command with @code{pass} or @code{nopass} to control whether your
3965 program sees that signal when you continue.
3967 The default is set to @code{nostop}, @code{noprint}, @code{pass} for
3968 non-erroneous signals such as @code{SIGALRM}, @code{SIGWINCH} and
3969 @code{SIGCHLD}, and to @code{stop}, @code{print}, @code{pass} for the
3972 You can also use the @code{signal} command to prevent your program from
3973 seeing a signal, or cause it to see a signal it normally would not see,
3974 or to give it any signal at any time. For example, if your program stopped
3975 due to some sort of memory reference error, you might store correct
3976 values into the erroneous variables and continue, hoping to see more
3977 execution; but your program would probably terminate immediately as
3978 a result of the fatal signal once it saw the signal. To prevent this,
3979 you can continue with @samp{signal 0}. @xref{Signaling, ,Giving your
3983 @section Stopping and starting multi-thread programs
3985 When your program has multiple threads (@pxref{Threads,, Debugging
3986 programs with multiple threads}), you can choose whether to set
3987 breakpoints on all threads, or on a particular thread.
3990 @cindex breakpoints and threads
3991 @cindex thread breakpoints
3992 @kindex break @dots{} thread @var{threadno}
3993 @item break @var{linespec} thread @var{threadno}
3994 @itemx break @var{linespec} thread @var{threadno} if @dots{}
3995 @var{linespec} specifies source lines; there are several ways of
3996 writing them, but the effect is always to specify some source line.
3998 Use the qualifier @samp{thread @var{threadno}} with a breakpoint command
3999 to specify that you only want @value{GDBN} to stop the program when a
4000 particular thread reaches this breakpoint. @var{threadno} is one of the
4001 numeric thread identifiers assigned by @value{GDBN}, shown in the first
4002 column of the @samp{info threads} display.
4004 If you do not specify @samp{thread @var{threadno}} when you set a
4005 breakpoint, the breakpoint applies to @emph{all} threads of your
4008 You can use the @code{thread} qualifier on conditional breakpoints as
4009 well; in this case, place @samp{thread @var{threadno}} before the
4010 breakpoint condition, like this:
4013 (@value{GDBP}) break frik.c:13 thread 28 if bartab > lim
4018 @cindex stopped threads
4019 @cindex threads, stopped
4020 Whenever your program stops under @value{GDBN} for any reason,
4021 @emph{all} threads of execution stop, not just the current thread. This
4022 allows you to examine the overall state of the program, including
4023 switching between threads, without worrying that things may change
4026 @cindex thread breakpoints and system calls
4027 @cindex system calls and thread breakpoints
4028 @cindex premature return from system calls
4029 There is an unfortunate side effect. If one thread stops for a
4030 breakpoint, or for some other reason, and another thread is blocked in a
4031 system call, then the system call may return prematurely. This is a
4032 consequence of the interaction between multiple threads and the signals
4033 that @value{GDBN} uses to implement breakpoints and other events that
4036 To handle this problem, your program should check the return value of
4037 each system call and react appropriately. This is good programming
4040 For example, do not write code like this:
4046 The call to @code{sleep} will return early if a different thread stops
4047 at a breakpoint or for some other reason.
4049 Instead, write this:
4054 unslept = sleep (unslept);
4057 A system call is allowed to return early, so the system is still
4058 conforming to its specification. But @value{GDBN} does cause your
4059 multi-threaded program to behave differently than it would without
4062 Also, @value{GDBN} uses internal breakpoints in the thread library to
4063 monitor certain events such as thread creation and thread destruction.
4064 When such an event happens, a system call in another thread may return
4065 prematurely, even though your program does not appear to stop.
4067 @cindex continuing threads
4068 @cindex threads, continuing
4069 Conversely, whenever you restart the program, @emph{all} threads start
4070 executing. @emph{This is true even when single-stepping} with commands
4071 like @code{step} or @code{next}.
4073 In particular, @value{GDBN} cannot single-step all threads in lockstep.
4074 Since thread scheduling is up to your debugging target's operating
4075 system (not controlled by @value{GDBN}), other threads may
4076 execute more than one statement while the current thread completes a
4077 single step. Moreover, in general other threads stop in the middle of a
4078 statement, rather than at a clean statement boundary, when the program
4081 You might even find your program stopped in another thread after
4082 continuing or even single-stepping. This happens whenever some other
4083 thread runs into a breakpoint, a signal, or an exception before the
4084 first thread completes whatever you requested.
4086 On some OSes, you can lock the OS scheduler and thus allow only a single
4090 @item set scheduler-locking @var{mode}
4091 @cindex scheduler locking mode
4092 @cindex lock scheduler
4093 Set the scheduler locking mode. If it is @code{off}, then there is no
4094 locking and any thread may run at any time. If @code{on}, then only the
4095 current thread may run when the inferior is resumed. The @code{step}
4096 mode optimizes for single-stepping. It stops other threads from
4097 ``seizing the prompt'' by preempting the current thread while you are
4098 stepping. Other threads will only rarely (or never) get a chance to run
4099 when you step. They are more likely to run when you @samp{next} over a
4100 function call, and they are completely free to run when you use commands
4101 like @samp{continue}, @samp{until}, or @samp{finish}. However, unless another
4102 thread hits a breakpoint during its timeslice, they will never steal the
4103 @value{GDBN} prompt away from the thread that you are debugging.
4105 @item show scheduler-locking
4106 Display the current scheduler locking mode.
4111 @chapter Examining the Stack
4113 When your program has stopped, the first thing you need to know is where it
4114 stopped and how it got there.
4117 Each time your program performs a function call, information about the call
4119 That information includes the location of the call in your program,
4120 the arguments of the call,
4121 and the local variables of the function being called.
4122 The information is saved in a block of data called a @dfn{stack frame}.
4123 The stack frames are allocated in a region of memory called the @dfn{call
4126 When your program stops, the @value{GDBN} commands for examining the
4127 stack allow you to see all of this information.
4129 @cindex selected frame
4130 One of the stack frames is @dfn{selected} by @value{GDBN} and many
4131 @value{GDBN} commands refer implicitly to the selected frame. In
4132 particular, whenever you ask @value{GDBN} for the value of a variable in
4133 your program, the value is found in the selected frame. There are
4134 special @value{GDBN} commands to select whichever frame you are
4135 interested in. @xref{Selection, ,Selecting a frame}.
4137 When your program stops, @value{GDBN} automatically selects the
4138 currently executing frame and describes it briefly, similar to the
4139 @code{frame} command (@pxref{Frame Info, ,Information about a frame}).
4142 * Frames:: Stack frames
4143 * Backtrace:: Backtraces
4144 * Selection:: Selecting a frame
4145 * Frame Info:: Information on a frame
4150 @section Stack frames
4152 @cindex frame, definition
4154 The call stack is divided up into contiguous pieces called @dfn{stack
4155 frames}, or @dfn{frames} for short; each frame is the data associated
4156 with one call to one function. The frame contains the arguments given
4157 to the function, the function's local variables, and the address at
4158 which the function is executing.
4160 @cindex initial frame
4161 @cindex outermost frame
4162 @cindex innermost frame
4163 When your program is started, the stack has only one frame, that of the
4164 function @code{main}. This is called the @dfn{initial} frame or the
4165 @dfn{outermost} frame. Each time a function is called, a new frame is
4166 made. Each time a function returns, the frame for that function invocation
4167 is eliminated. If a function is recursive, there can be many frames for
4168 the same function. The frame for the function in which execution is
4169 actually occurring is called the @dfn{innermost} frame. This is the most
4170 recently created of all the stack frames that still exist.
4172 @cindex frame pointer
4173 Inside your program, stack frames are identified by their addresses. A
4174 stack frame consists of many bytes, each of which has its own address; each
4175 kind of computer has a convention for choosing one byte whose
4176 address serves as the address of the frame. Usually this address is kept
4177 in a register called the @dfn{frame pointer register}
4178 (@pxref{Registers, $fp}) while execution is going on in that frame.
4180 @cindex frame number
4181 @value{GDBN} assigns numbers to all existing stack frames, starting with
4182 zero for the innermost frame, one for the frame that called it,
4183 and so on upward. These numbers do not really exist in your program;
4184 they are assigned by @value{GDBN} to give you a way of designating stack
4185 frames in @value{GDBN} commands.
4187 @c The -fomit-frame-pointer below perennially causes hbox overflow
4188 @c underflow problems.
4189 @cindex frameless execution
4190 Some compilers provide a way to compile functions so that they operate
4191 without stack frames. (For example, the @value{GCC} option
4193 @samp{-fomit-frame-pointer}
4195 generates functions without a frame.)
4196 This is occasionally done with heavily used library functions to save
4197 the frame setup time. @value{GDBN} has limited facilities for dealing
4198 with these function invocations. If the innermost function invocation
4199 has no stack frame, @value{GDBN} nevertheless regards it as though
4200 it had a separate frame, which is numbered zero as usual, allowing
4201 correct tracing of the function call chain. However, @value{GDBN} has
4202 no provision for frameless functions elsewhere in the stack.
4205 @kindex frame@r{, command}
4206 @cindex current stack frame
4207 @item frame @var{args}
4208 The @code{frame} command allows you to move from one stack frame to another,
4209 and to print the stack frame you select. @var{args} may be either the
4210 address of the frame or the stack frame number. Without an argument,
4211 @code{frame} prints the current stack frame.
4213 @kindex select-frame
4214 @cindex selecting frame silently
4216 The @code{select-frame} command allows you to move from one stack frame
4217 to another without printing the frame. This is the silent version of
4225 @cindex call stack traces
4226 A backtrace is a summary of how your program got where it is. It shows one
4227 line per frame, for many frames, starting with the currently executing
4228 frame (frame zero), followed by its caller (frame one), and on up the
4233 @kindex bt @r{(@code{backtrace})}
4236 Print a backtrace of the entire stack: one line per frame for all
4237 frames in the stack.
4239 You can stop the backtrace at any time by typing the system interrupt
4240 character, normally @kbd{C-c}.
4242 @item backtrace @var{n}
4244 Similar, but print only the innermost @var{n} frames.
4246 @item backtrace -@var{n}
4248 Similar, but print only the outermost @var{n} frames.
4250 @item backtrace full
4251 Print the values of the local variables also.
4257 The names @code{where} and @code{info stack} (abbreviated @code{info s})
4258 are additional aliases for @code{backtrace}.
4260 Each line in the backtrace shows the frame number and the function name.
4261 The program counter value is also shown---unless you use @code{set
4262 print address off}. The backtrace also shows the source file name and
4263 line number, as well as the arguments to the function. The program
4264 counter value is omitted if it is at the beginning of the code for that
4267 Here is an example of a backtrace. It was made with the command
4268 @samp{bt 3}, so it shows the innermost three frames.
4272 #0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8)
4274 #1 0x6e38 in expand_macro (sym=0x2b600) at macro.c:242
4275 #2 0x6840 in expand_token (obs=0x0, t=177664, td=0xf7fffb08)
4277 (More stack frames follow...)
4282 The display for frame zero does not begin with a program counter
4283 value, indicating that your program has stopped at the beginning of the
4284 code for line @code{993} of @code{builtin.c}.
4286 @cindex value optimized out, in backtrace
4287 @cindex function call arguments, optimized out
4288 If your program was compiled with optimizations, some compilers will
4289 optimize away arguments passed to functions if those arguments are
4290 never used after the call. Such optimizations generate code that
4291 passes arguments through registers, but doesn't store those arguments
4292 in the stack frame. @value{GDBN} has no way of displaying such
4293 arguments in stack frames other than the innermost one. Here's what
4294 such a backtrace might look like:
4298 #0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8)
4300 #1 0x6e38 in expand_macro (sym=<value optimized out>) at macro.c:242
4301 #2 0x6840 in expand_token (obs=0x0, t=<value optimized out>, td=0xf7fffb08)
4303 (More stack frames follow...)
4308 The values of arguments that were not saved in their stack frames are
4309 shown as @samp{<value optimized out>}.
4311 If you need to display the values of such optimized-out arguments,
4312 either deduce that from other variables whose values depend on the one
4313 you are interested in, or recompile without optimizations.
4315 @cindex backtrace beyond @code{main} function
4316 @cindex program entry point
4317 @cindex startup code, and backtrace
4318 Most programs have a standard user entry point---a place where system
4319 libraries and startup code transition into user code. For C this is
4320 @code{main}@footnote{
4321 Note that embedded programs (the so-called ``free-standing''
4322 environment) are not required to have a @code{main} function as the
4323 entry point. They could even have multiple entry points.}.
4324 When @value{GDBN} finds the entry function in a backtrace
4325 it will terminate the backtrace, to avoid tracing into highly
4326 system-specific (and generally uninteresting) code.
4328 If you need to examine the startup code, or limit the number of levels
4329 in a backtrace, you can change this behavior:
4332 @item set backtrace past-main
4333 @itemx set backtrace past-main on
4334 @kindex set backtrace
4335 Backtraces will continue past the user entry point.
4337 @item set backtrace past-main off
4338 Backtraces will stop when they encounter the user entry point. This is the
4341 @item show backtrace past-main
4342 @kindex show backtrace
4343 Display the current user entry point backtrace policy.
4345 @item set backtrace past-entry
4346 @itemx set backtrace past-entry on
4347 Backtraces will continue past the internal entry point of an application.
4348 This entry point is encoded by the linker when the application is built,
4349 and is likely before the user entry point @code{main} (or equivalent) is called.
4351 @item set backtrace past-entry off
4352 Backtraces will stop when they encouter the internal entry point of an
4353 application. This is the default.
4355 @item show backtrace past-entry
4356 Display the current internal entry point backtrace policy.
4358 @item set backtrace limit @var{n}
4359 @itemx set backtrace limit 0
4360 @cindex backtrace limit
4361 Limit the backtrace to @var{n} levels. A value of zero means
4364 @item show backtrace limit
4365 Display the current limit on backtrace levels.
4369 @section Selecting a frame
4371 Most commands for examining the stack and other data in your program work on
4372 whichever stack frame is selected at the moment. Here are the commands for
4373 selecting a stack frame; all of them finish by printing a brief description
4374 of the stack frame just selected.
4377 @kindex frame@r{, selecting}
4378 @kindex f @r{(@code{frame})}
4381 Select frame number @var{n}. Recall that frame zero is the innermost
4382 (currently executing) frame, frame one is the frame that called the
4383 innermost one, and so on. The highest-numbered frame is the one for
4386 @item frame @var{addr}
4388 Select the frame at address @var{addr}. This is useful mainly if the
4389 chaining of stack frames has been damaged by a bug, making it
4390 impossible for @value{GDBN} to assign numbers properly to all frames. In
4391 addition, this can be useful when your program has multiple stacks and
4392 switches between them.
4394 On the SPARC architecture, @code{frame} needs two addresses to
4395 select an arbitrary frame: a frame pointer and a stack pointer.
4397 On the MIPS and Alpha architecture, it needs two addresses: a stack
4398 pointer and a program counter.
4400 On the 29k architecture, it needs three addresses: a register stack
4401 pointer, a program counter, and a memory stack pointer.
4402 @c note to future updaters: this is conditioned on a flag
4403 @c SETUP_ARBITRARY_FRAME in the tm-*.h files. The above is up to date
4404 @c as of 27 Jan 1994.
4408 Move @var{n} frames up the stack. For positive numbers @var{n}, this
4409 advances toward the outermost frame, to higher frame numbers, to frames
4410 that have existed longer. @var{n} defaults to one.
4413 @kindex do @r{(@code{down})}
4415 Move @var{n} frames down the stack. For positive numbers @var{n}, this
4416 advances toward the innermost frame, to lower frame numbers, to frames
4417 that were created more recently. @var{n} defaults to one. You may
4418 abbreviate @code{down} as @code{do}.
4421 All of these commands end by printing two lines of output describing the
4422 frame. The first line shows the frame number, the function name, the
4423 arguments, and the source file and line number of execution in that
4424 frame. The second line shows the text of that source line.
4432 #1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc)
4434 10 read_input_file (argv[i]);
4438 After such a printout, the @code{list} command with no arguments
4439 prints ten lines centered on the point of execution in the frame.
4440 You can also edit the program at the point of execution with your favorite
4441 editing program by typing @code{edit}.
4442 @xref{List, ,Printing source lines},
4446 @kindex down-silently
4448 @item up-silently @var{n}
4449 @itemx down-silently @var{n}
4450 These two commands are variants of @code{up} and @code{down},
4451 respectively; they differ in that they do their work silently, without
4452 causing display of the new frame. They are intended primarily for use
4453 in @value{GDBN} command scripts, where the output might be unnecessary and
4458 @section Information about a frame
4460 There are several other commands to print information about the selected
4466 When used without any argument, this command does not change which
4467 frame is selected, but prints a brief description of the currently
4468 selected stack frame. It can be abbreviated @code{f}. With an
4469 argument, this command is used to select a stack frame.
4470 @xref{Selection, ,Selecting a frame}.
4473 @kindex info f @r{(@code{info frame})}
4476 This command prints a verbose description of the selected stack frame,
4481 the address of the frame
4483 the address of the next frame down (called by this frame)
4485 the address of the next frame up (caller of this frame)
4487 the language in which the source code corresponding to this frame is written
4489 the address of the frame's arguments
4491 the address of the frame's local variables
4493 the program counter saved in it (the address of execution in the caller frame)
4495 which registers were saved in the frame
4498 @noindent The verbose description is useful when
4499 something has gone wrong that has made the stack format fail to fit
4500 the usual conventions.
4502 @item info frame @var{addr}
4503 @itemx info f @var{addr}
4504 Print a verbose description of the frame at address @var{addr}, without
4505 selecting that frame. The selected frame remains unchanged by this
4506 command. This requires the same kind of address (more than one for some
4507 architectures) that you specify in the @code{frame} command.
4508 @xref{Selection, ,Selecting a frame}.
4512 Print the arguments of the selected frame, each on a separate line.
4516 Print the local variables of the selected frame, each on a separate
4517 line. These are all variables (declared either static or automatic)
4518 accessible at the point of execution of the selected frame.
4521 @cindex catch exceptions, list active handlers
4522 @cindex exception handlers, how to list
4524 Print a list of all the exception handlers that are active in the
4525 current stack frame at the current point of execution. To see other
4526 exception handlers, visit the associated frame (using the @code{up},
4527 @code{down}, or @code{frame} commands); then type @code{info catch}.
4528 @xref{Set Catchpoints, , Setting catchpoints}.
4534 @chapter Examining Source Files
4536 @value{GDBN} can print parts of your program's source, since the debugging
4537 information recorded in the program tells @value{GDBN} what source files were
4538 used to build it. When your program stops, @value{GDBN} spontaneously prints
4539 the line where it stopped. Likewise, when you select a stack frame
4540 (@pxref{Selection, ,Selecting a frame}), @value{GDBN} prints the line where
4541 execution in that frame has stopped. You can print other portions of
4542 source files by explicit command.
4544 If you use @value{GDBN} through its @sc{gnu} Emacs interface, you may
4545 prefer to use Emacs facilities to view source; see @ref{Emacs, ,Using
4546 @value{GDBN} under @sc{gnu} Emacs}.
4549 * List:: Printing source lines
4550 * Edit:: Editing source files
4551 * Search:: Searching source files
4552 * Source Path:: Specifying source directories
4553 * Machine Code:: Source and machine code
4557 @section Printing source lines
4560 @kindex l @r{(@code{list})}
4561 To print lines from a source file, use the @code{list} command
4562 (abbreviated @code{l}). By default, ten lines are printed.
4563 There are several ways to specify what part of the file you want to print.
4565 Here are the forms of the @code{list} command most commonly used:
4568 @item list @var{linenum}
4569 Print lines centered around line number @var{linenum} in the
4570 current source file.
4572 @item list @var{function}
4573 Print lines centered around the beginning of function
4577 Print more lines. If the last lines printed were printed with a
4578 @code{list} command, this prints lines following the last lines
4579 printed; however, if the last line printed was a solitary line printed
4580 as part of displaying a stack frame (@pxref{Stack, ,Examining the
4581 Stack}), this prints lines centered around that line.
4584 Print lines just before the lines last printed.
4587 @cindex @code{list}, how many lines to display
4588 By default, @value{GDBN} prints ten source lines with any of these forms of
4589 the @code{list} command. You can change this using @code{set listsize}:
4592 @kindex set listsize
4593 @item set listsize @var{count}
4594 Make the @code{list} command display @var{count} source lines (unless
4595 the @code{list} argument explicitly specifies some other number).
4597 @kindex show listsize
4599 Display the number of lines that @code{list} prints.
4602 Repeating a @code{list} command with @key{RET} discards the argument,
4603 so it is equivalent to typing just @code{list}. This is more useful
4604 than listing the same lines again. An exception is made for an
4605 argument of @samp{-}; that argument is preserved in repetition so that
4606 each repetition moves up in the source file.
4609 In general, the @code{list} command expects you to supply zero, one or two
4610 @dfn{linespecs}. Linespecs specify source lines; there are several ways
4611 of writing them, but the effect is always to specify some source line.
4612 Here is a complete description of the possible arguments for @code{list}:
4615 @item list @var{linespec}
4616 Print lines centered around the line specified by @var{linespec}.
4618 @item list @var{first},@var{last}
4619 Print lines from @var{first} to @var{last}. Both arguments are
4622 @item list ,@var{last}
4623 Print lines ending with @var{last}.
4625 @item list @var{first},
4626 Print lines starting with @var{first}.
4629 Print lines just after the lines last printed.
4632 Print lines just before the lines last printed.
4635 As described in the preceding table.
4638 Here are the ways of specifying a single source line---all the
4643 Specifies line @var{number} of the current source file.
4644 When a @code{list} command has two linespecs, this refers to
4645 the same source file as the first linespec.
4648 Specifies the line @var{offset} lines after the last line printed.
4649 When used as the second linespec in a @code{list} command that has
4650 two, this specifies the line @var{offset} lines down from the
4654 Specifies the line @var{offset} lines before the last line printed.
4656 @item @var{filename}:@var{number}
4657 Specifies line @var{number} in the source file @var{filename}.
4659 @item @var{function}
4660 Specifies the line that begins the body of the function @var{function}.
4661 For example: in C, this is the line with the open brace.
4663 @item @var{filename}:@var{function}
4664 Specifies the line of the open-brace that begins the body of the
4665 function @var{function} in the file @var{filename}. You only need the
4666 file name with a function name to avoid ambiguity when there are
4667 identically named functions in different source files.
4669 @item *@var{address}
4670 Specifies the line containing the program address @var{address}.
4671 @var{address} may be any expression.
4675 @section Editing source files
4676 @cindex editing source files
4679 @kindex e @r{(@code{edit})}
4680 To edit the lines in a source file, use the @code{edit} command.
4681 The editing program of your choice
4682 is invoked with the current line set to
4683 the active line in the program.
4684 Alternatively, there are several ways to specify what part of the file you
4685 want to print if you want to see other parts of the program.
4687 Here are the forms of the @code{edit} command most commonly used:
4691 Edit the current source file at the active line number in the program.
4693 @item edit @var{number}
4694 Edit the current source file with @var{number} as the active line number.
4696 @item edit @var{function}
4697 Edit the file containing @var{function} at the beginning of its definition.
4699 @item edit @var{filename}:@var{number}
4700 Specifies line @var{number} in the source file @var{filename}.
4702 @item edit @var{filename}:@var{function}
4703 Specifies the line that begins the body of the
4704 function @var{function} in the file @var{filename}. You only need the
4705 file name with a function name to avoid ambiguity when there are
4706 identically named functions in different source files.
4708 @item edit *@var{address}
4709 Specifies the line containing the program address @var{address}.
4710 @var{address} may be any expression.
4713 @subsection Choosing your editor
4714 You can customize @value{GDBN} to use any editor you want
4716 The only restriction is that your editor (say @code{ex}), recognizes the
4717 following command-line syntax:
4719 ex +@var{number} file
4721 The optional numeric value +@var{number} specifies the number of the line in
4722 the file where to start editing.}.
4723 By default, it is @file{@value{EDITOR}}, but you can change this
4724 by setting the environment variable @code{EDITOR} before using
4725 @value{GDBN}. For example, to configure @value{GDBN} to use the
4726 @code{vi} editor, you could use these commands with the @code{sh} shell:
4732 or in the @code{csh} shell,
4734 setenv EDITOR /usr/bin/vi
4739 @section Searching source files
4740 @cindex searching source files
4742 There are two commands for searching through the current source file for a
4747 @kindex forward-search
4748 @item forward-search @var{regexp}
4749 @itemx search @var{regexp}
4750 The command @samp{forward-search @var{regexp}} checks each line,
4751 starting with the one following the last line listed, for a match for
4752 @var{regexp}. It lists the line that is found. You can use the
4753 synonym @samp{search @var{regexp}} or abbreviate the command name as
4756 @kindex reverse-search
4757 @item reverse-search @var{regexp}
4758 The command @samp{reverse-search @var{regexp}} checks each line, starting
4759 with the one before the last line listed and going backward, for a match
4760 for @var{regexp}. It lists the line that is found. You can abbreviate
4761 this command as @code{rev}.
4765 @section Specifying source directories
4768 @cindex directories for source files
4769 Executable programs sometimes do not record the directories of the source
4770 files from which they were compiled, just the names. Even when they do,
4771 the directories could be moved between the compilation and your debugging
4772 session. @value{GDBN} has a list of directories to search for source files;
4773 this is called the @dfn{source path}. Each time @value{GDBN} wants a source file,
4774 it tries all the directories in the list, in the order they are present
4775 in the list, until it finds a file with the desired name.
4777 For example, suppose an executable references the file
4778 @file{/usr/src/foo-1.0/lib/foo.c}, and our source path is
4779 @file{/mnt/cross}. The file is first looked up literally; if this
4780 fails, @file{/mnt/cross/usr/src/foo-1.0/lib/foo.c} is tried; if this
4781 fails, @file{/mnt/cross/foo.c} is opened; if this fails, an error
4782 message is printed. @value{GDBN} does not look up the parts of the
4783 source file name, such as @file{/mnt/cross/src/foo-1.0/lib/foo.c}.
4784 Likewise, the subdirectories of the source path are not searched: if
4785 the source path is @file{/mnt/cross}, and the binary refers to
4786 @file{foo.c}, @value{GDBN} would not find it under
4787 @file{/mnt/cross/usr/src/foo-1.0/lib}.
4789 Plain file names, relative file names with leading directories, file
4790 names containing dots, etc.@: are all treated as described above; for
4791 instance, if the source path is @file{/mnt/cross}, and the source file
4792 is recorded as @file{../lib/foo.c}, @value{GDBN} would first try
4793 @file{../lib/foo.c}, then @file{/mnt/cross/../lib/foo.c}, and after
4794 that---@file{/mnt/cross/foo.c}.
4796 Note that the executable search path is @emph{not} used to locate the
4797 source files. Neither is the current working directory, unless it
4798 happens to be in the source path.
4800 Whenever you reset or rearrange the source path, @value{GDBN} clears out
4801 any information it has cached about where source files are found and where
4802 each line is in the file.
4806 When you start @value{GDBN}, its source path includes only @samp{cdir}
4807 and @samp{cwd}, in that order.
4808 To add other directories, use the @code{directory} command.
4811 @item directory @var{dirname} @dots{}
4812 @item dir @var{dirname} @dots{}
4813 Add directory @var{dirname} to the front of the source path. Several
4814 directory names may be given to this command, separated by @samp{:}
4815 (@samp{;} on MS-DOS and MS-Windows, where @samp{:} usually appears as
4816 part of absolute file names) or
4817 whitespace. You may specify a directory that is already in the source
4818 path; this moves it forward, so @value{GDBN} searches it sooner.
4822 @vindex $cdir@r{, convenience variable}
4823 @vindex $cwdr@r{, convenience variable}
4824 @cindex compilation directory
4825 @cindex current directory
4826 @cindex working directory
4827 @cindex directory, current
4828 @cindex directory, compilation
4829 You can use the string @samp{$cdir} to refer to the compilation
4830 directory (if one is recorded), and @samp{$cwd} to refer to the current
4831 working directory. @samp{$cwd} is not the same as @samp{.}---the former
4832 tracks the current working directory as it changes during your @value{GDBN}
4833 session, while the latter is immediately expanded to the current
4834 directory at the time you add an entry to the source path.
4837 Reset the source path to empty again. This requires confirmation.
4839 @c RET-repeat for @code{directory} is explicitly disabled, but since
4840 @c repeating it would be a no-op we do not say that. (thanks to RMS)
4842 @item show directories
4843 @kindex show directories
4844 Print the source path: show which directories it contains.
4847 If your source path is cluttered with directories that are no longer of
4848 interest, @value{GDBN} may sometimes cause confusion by finding the wrong
4849 versions of source. You can correct the situation as follows:
4853 Use @code{directory} with no argument to reset the source path to empty.
4856 Use @code{directory} with suitable arguments to reinstall the
4857 directories you want in the source path. You can add all the
4858 directories in one command.
4862 @section Source and machine code
4863 @cindex source line and its code address
4865 You can use the command @code{info line} to map source lines to program
4866 addresses (and vice versa), and the command @code{disassemble} to display
4867 a range of addresses as machine instructions. When run under @sc{gnu} Emacs
4868 mode, the @code{info line} command causes the arrow to point to the
4869 line specified. Also, @code{info line} prints addresses in symbolic form as
4874 @item info line @var{linespec}
4875 Print the starting and ending addresses of the compiled code for
4876 source line @var{linespec}. You can specify source lines in any of
4877 the ways understood by the @code{list} command (@pxref{List, ,Printing
4881 For example, we can use @code{info line} to discover the location of
4882 the object code for the first line of function
4883 @code{m4_changequote}:
4885 @c FIXME: I think this example should also show the addresses in
4886 @c symbolic form, as they usually would be displayed.
4888 (@value{GDBP}) info line m4_changequote
4889 Line 895 of "builtin.c" starts at pc 0x634c and ends at 0x6350.
4893 @cindex code address and its source line
4894 We can also inquire (using @code{*@var{addr}} as the form for
4895 @var{linespec}) what source line covers a particular address:
4897 (@value{GDBP}) info line *0x63ff
4898 Line 926 of "builtin.c" starts at pc 0x63e4 and ends at 0x6404.
4901 @cindex @code{$_} and @code{info line}
4902 @cindex @code{x} command, default address
4903 @kindex x@r{(examine), and} info line
4904 After @code{info line}, the default address for the @code{x} command
4905 is changed to the starting address of the line, so that @samp{x/i} is
4906 sufficient to begin examining the machine code (@pxref{Memory,
4907 ,Examining memory}). Also, this address is saved as the value of the
4908 convenience variable @code{$_} (@pxref{Convenience Vars, ,Convenience
4913 @cindex assembly instructions
4914 @cindex instructions, assembly
4915 @cindex machine instructions
4916 @cindex listing machine instructions
4918 This specialized command dumps a range of memory as machine
4919 instructions. The default memory range is the function surrounding the
4920 program counter of the selected frame. A single argument to this
4921 command is a program counter value; @value{GDBN} dumps the function
4922 surrounding this value. Two arguments specify a range of addresses
4923 (first inclusive, second exclusive) to dump.
4926 The following example shows the disassembly of a range of addresses of
4927 HP PA-RISC 2.0 code:
4930 (@value{GDBP}) disas 0x32c4 0x32e4
4931 Dump of assembler code from 0x32c4 to 0x32e4:
4932 0x32c4 <main+204>: addil 0,dp
4933 0x32c8 <main+208>: ldw 0x22c(sr0,r1),r26
4934 0x32cc <main+212>: ldil 0x3000,r31
4935 0x32d0 <main+216>: ble 0x3f8(sr4,r31)
4936 0x32d4 <main+220>: ldo 0(r31),rp
4937 0x32d8 <main+224>: addil -0x800,dp
4938 0x32dc <main+228>: ldo 0x588(r1),r26
4939 0x32e0 <main+232>: ldil 0x3000,r31
4940 End of assembler dump.
4943 Some architectures have more than one commonly-used set of instruction
4944 mnemonics or other syntax.
4946 For programs that were dynamically linked and use shared libraries,
4947 instructions that call functions or branch to locations in the shared
4948 libraries might show a seemingly bogus location---it's actually a
4949 location of the relocation table. On some architectures, @value{GDBN}
4950 might be able to resolve these to actual function names.
4953 @kindex set disassembly-flavor
4954 @cindex Intel disassembly flavor
4955 @cindex AT&T disassembly flavor
4956 @item set disassembly-flavor @var{instruction-set}
4957 Select the instruction set to use when disassembling the
4958 program via the @code{disassemble} or @code{x/i} commands.
4960 Currently this command is only defined for the Intel x86 family. You
4961 can set @var{instruction-set} to either @code{intel} or @code{att}.
4962 The default is @code{att}, the AT&T flavor used by default by Unix
4963 assemblers for x86-based targets.
4965 @kindex show disassembly-flavor
4966 @item show disassembly-flavor
4967 Show the current setting of the disassembly flavor.
4972 @chapter Examining Data
4974 @cindex printing data
4975 @cindex examining data
4978 @c "inspect" is not quite a synonym if you are using Epoch, which we do not
4979 @c document because it is nonstandard... Under Epoch it displays in a
4980 @c different window or something like that.
4981 The usual way to examine data in your program is with the @code{print}
4982 command (abbreviated @code{p}), or its synonym @code{inspect}. It
4983 evaluates and prints the value of an expression of the language your
4984 program is written in (@pxref{Languages, ,Using @value{GDBN} with
4985 Different Languages}).
4988 @item print @var{expr}
4989 @itemx print /@var{f} @var{expr}
4990 @var{expr} is an expression (in the source language). By default the
4991 value of @var{expr} is printed in a format appropriate to its data type;
4992 you can choose a different format by specifying @samp{/@var{f}}, where
4993 @var{f} is a letter specifying the format; see @ref{Output Formats,,Output
4997 @itemx print /@var{f}
4998 @cindex reprint the last value
4999 If you omit @var{expr}, @value{GDBN} displays the last value again (from the
5000 @dfn{value history}; @pxref{Value History, ,Value history}). This allows you to
5001 conveniently inspect the same value in an alternative format.
5004 A more low-level way of examining data is with the @code{x} command.
5005 It examines data in memory at a specified address and prints it in a
5006 specified format. @xref{Memory, ,Examining memory}.
5008 If you are interested in information about types, or about how the
5009 fields of a struct or a class are declared, use the @code{ptype @var{exp}}
5010 command rather than @code{print}. @xref{Symbols, ,Examining the Symbol
5014 * Expressions:: Expressions
5015 * Variables:: Program variables
5016 * Arrays:: Artificial arrays
5017 * Output Formats:: Output formats
5018 * Memory:: Examining memory
5019 * Auto Display:: Automatic display
5020 * Print Settings:: Print settings
5021 * Value History:: Value history
5022 * Convenience Vars:: Convenience variables
5023 * Registers:: Registers
5024 * Floating Point Hardware:: Floating point hardware
5025 * Vector Unit:: Vector Unit
5026 * OS Information:: Auxiliary data provided by operating system
5027 * Memory Region Attributes:: Memory region attributes
5028 * Dump/Restore Files:: Copy between memory and a file
5029 * Core File Generation:: Cause a program dump its core
5030 * Character Sets:: Debugging programs that use a different
5031 character set than GDB does
5032 * Caching Remote Data:: Data caching for remote targets
5036 @section Expressions
5039 @code{print} and many other @value{GDBN} commands accept an expression and
5040 compute its value. Any kind of constant, variable or operator defined
5041 by the programming language you are using is valid in an expression in
5042 @value{GDBN}. This includes conditional expressions, function calls,
5043 casts, and string constants. It also includes preprocessor macros, if
5044 you compiled your program to include this information; see
5047 @cindex arrays in expressions
5048 @value{GDBN} supports array constants in expressions input by
5049 the user. The syntax is @{@var{element}, @var{element}@dots{}@}. For example,
5050 you can use the command @code{print @{1, 2, 3@}} to build up an array in
5051 memory that is @code{malloc}ed in the target program.
5053 Because C is so widespread, most of the expressions shown in examples in
5054 this manual are in C. @xref{Languages, , Using @value{GDBN} with Different
5055 Languages}, for information on how to use expressions in other
5058 In this section, we discuss operators that you can use in @value{GDBN}
5059 expressions regardless of your programming language.
5061 @cindex casts, in expressions
5062 Casts are supported in all languages, not just in C, because it is so
5063 useful to cast a number into a pointer in order to examine a structure
5064 at that address in memory.
5065 @c FIXME: casts supported---Mod2 true?
5067 @value{GDBN} supports these operators, in addition to those common
5068 to programming languages:
5072 @samp{@@} is a binary operator for treating parts of memory as arrays.
5073 @xref{Arrays, ,Artificial arrays}, for more information.
5076 @samp{::} allows you to specify a variable in terms of the file or
5077 function where it is defined. @xref{Variables, ,Program variables}.
5079 @cindex @{@var{type}@}
5080 @cindex type casting memory
5081 @cindex memory, viewing as typed object
5082 @cindex casts, to view memory
5083 @item @{@var{type}@} @var{addr}
5084 Refers to an object of type @var{type} stored at address @var{addr} in
5085 memory. @var{addr} may be any expression whose value is an integer or
5086 pointer (but parentheses are required around binary operators, just as in
5087 a cast). This construct is allowed regardless of what kind of data is
5088 normally supposed to reside at @var{addr}.
5092 @section Program variables
5094 The most common kind of expression to use is the name of a variable
5097 Variables in expressions are understood in the selected stack frame
5098 (@pxref{Selection, ,Selecting a frame}); they must be either:
5102 global (or file-static)
5109 visible according to the scope rules of the
5110 programming language from the point of execution in that frame
5113 @noindent This means that in the function
5128 you can examine and use the variable @code{a} whenever your program is
5129 executing within the function @code{foo}, but you can only use or
5130 examine the variable @code{b} while your program is executing inside
5131 the block where @code{b} is declared.
5133 @cindex variable name conflict
5134 There is an exception: you can refer to a variable or function whose
5135 scope is a single source file even if the current execution point is not
5136 in this file. But it is possible to have more than one such variable or
5137 function with the same name (in different source files). If that
5138 happens, referring to that name has unpredictable effects. If you wish,
5139 you can specify a static variable in a particular function or file,
5140 using the colon-colon (@code{::}) notation:
5142 @cindex colon-colon, context for variables/functions
5144 @c info cannot cope with a :: index entry, but why deprive hard copy readers?
5145 @cindex @code{::}, context for variables/functions
5148 @var{file}::@var{variable}
5149 @var{function}::@var{variable}
5153 Here @var{file} or @var{function} is the name of the context for the
5154 static @var{variable}. In the case of file names, you can use quotes to
5155 make sure @value{GDBN} parses the file name as a single word---for example,
5156 to print a global value of @code{x} defined in @file{f2.c}:
5159 (@value{GDBP}) p 'f2.c'::x
5162 @cindex C@t{++} scope resolution
5163 This use of @samp{::} is very rarely in conflict with the very similar
5164 use of the same notation in C@t{++}. @value{GDBN} also supports use of the C@t{++}
5165 scope resolution operator in @value{GDBN} expressions.
5166 @c FIXME: Um, so what happens in one of those rare cases where it's in
5169 @cindex wrong values
5170 @cindex variable values, wrong
5171 @cindex function entry/exit, wrong values of variables
5172 @cindex optimized code, wrong values of variables
5174 @emph{Warning:} Occasionally, a local variable may appear to have the
5175 wrong value at certain points in a function---just after entry to a new
5176 scope, and just before exit.
5178 You may see this problem when you are stepping by machine instructions.
5179 This is because, on most machines, it takes more than one instruction to
5180 set up a stack frame (including local variable definitions); if you are
5181 stepping by machine instructions, variables may appear to have the wrong
5182 values until the stack frame is completely built. On exit, it usually
5183 also takes more than one machine instruction to destroy a stack frame;
5184 after you begin stepping through that group of instructions, local
5185 variable definitions may be gone.
5187 This may also happen when the compiler does significant optimizations.
5188 To be sure of always seeing accurate values, turn off all optimization
5191 @cindex ``No symbol "foo" in current context''
5192 Another possible effect of compiler optimizations is to optimize
5193 unused variables out of existence, or assign variables to registers (as
5194 opposed to memory addresses). Depending on the support for such cases
5195 offered by the debug info format used by the compiler, @value{GDBN}
5196 might not be able to display values for such local variables. If that
5197 happens, @value{GDBN} will print a message like this:
5200 No symbol "foo" in current context.
5203 To solve such problems, either recompile without optimizations, or use a
5204 different debug info format, if the compiler supports several such
5205 formats. For example, @value{NGCC}, the @sc{gnu} C/C@t{++} compiler,
5206 usually supports the @option{-gstabs+} option. @option{-gstabs+}
5207 produces debug info in a format that is superior to formats such as
5208 COFF. You may be able to use DWARF 2 (@option{-gdwarf-2}), which is also
5209 an effective form for debug info. @xref{Debugging Options,,Options
5210 for Debugging Your Program or @sc{gnu} CC, gcc.info, Using @sc{gnu} CC}.
5211 @xref{C, , Debugging C++}, for more info about debug info formats
5212 that are best suited to C@t{++} programs.
5215 @section Artificial arrays
5217 @cindex artificial array
5219 @kindex @@@r{, referencing memory as an array}
5220 It is often useful to print out several successive objects of the
5221 same type in memory; a section of an array, or an array of
5222 dynamically determined size for which only a pointer exists in the
5225 You can do this by referring to a contiguous span of memory as an
5226 @dfn{artificial array}, using the binary operator @samp{@@}. The left
5227 operand of @samp{@@} should be the first element of the desired array
5228 and be an individual object. The right operand should be the desired length
5229 of the array. The result is an array value whose elements are all of
5230 the type of the left argument. The first element is actually the left
5231 argument; the second element comes from bytes of memory immediately
5232 following those that hold the first element, and so on. Here is an
5233 example. If a program says
5236 int *array = (int *) malloc (len * sizeof (int));
5240 you can print the contents of @code{array} with
5246 The left operand of @samp{@@} must reside in memory. Array values made
5247 with @samp{@@} in this way behave just like other arrays in terms of
5248 subscripting, and are coerced to pointers when used in expressions.
5249 Artificial arrays most often appear in expressions via the value history
5250 (@pxref{Value History, ,Value history}), after printing one out.
5252 Another way to create an artificial array is to use a cast.
5253 This re-interprets a value as if it were an array.
5254 The value need not be in memory:
5256 (@value{GDBP}) p/x (short[2])0x12345678
5257 $1 = @{0x1234, 0x5678@}
5260 As a convenience, if you leave the array length out (as in
5261 @samp{(@var{type}[])@var{value}}) @value{GDBN} calculates the size to fill
5262 the value (as @samp{sizeof(@var{value})/sizeof(@var{type})}:
5264 (@value{GDBP}) p/x (short[])0x12345678
5265 $2 = @{0x1234, 0x5678@}
5268 Sometimes the artificial array mechanism is not quite enough; in
5269 moderately complex data structures, the elements of interest may not
5270 actually be adjacent---for example, if you are interested in the values
5271 of pointers in an array. One useful work-around in this situation is
5272 to use a convenience variable (@pxref{Convenience Vars, ,Convenience
5273 variables}) as a counter in an expression that prints the first
5274 interesting value, and then repeat that expression via @key{RET}. For
5275 instance, suppose you have an array @code{dtab} of pointers to
5276 structures, and you are interested in the values of a field @code{fv}
5277 in each structure. Here is an example of what you might type:
5287 @node Output Formats
5288 @section Output formats
5290 @cindex formatted output
5291 @cindex output formats
5292 By default, @value{GDBN} prints a value according to its data type. Sometimes
5293 this is not what you want. For example, you might want to print a number
5294 in hex, or a pointer in decimal. Or you might want to view data in memory
5295 at a certain address as a character string or as an instruction. To do
5296 these things, specify an @dfn{output format} when you print a value.
5298 The simplest use of output formats is to say how to print a value
5299 already computed. This is done by starting the arguments of the
5300 @code{print} command with a slash and a format letter. The format
5301 letters supported are:
5305 Regard the bits of the value as an integer, and print the integer in
5309 Print as integer in signed decimal.
5312 Print as integer in unsigned decimal.
5315 Print as integer in octal.
5318 Print as integer in binary. The letter @samp{t} stands for ``two''.
5319 @footnote{@samp{b} cannot be used because these format letters are also
5320 used with the @code{x} command, where @samp{b} stands for ``byte'';
5321 see @ref{Memory,,Examining memory}.}
5324 @cindex unknown address, locating
5325 @cindex locate address
5326 Print as an address, both absolute in hexadecimal and as an offset from
5327 the nearest preceding symbol. You can use this format used to discover
5328 where (in what function) an unknown address is located:
5331 (@value{GDBP}) p/a 0x54320
5332 $3 = 0x54320 <_initialize_vx+396>
5336 The command @code{info symbol 0x54320} yields similar results.
5337 @xref{Symbols, info symbol}.
5340 Regard as an integer and print it as a character constant. This
5341 prints both the numerical value and its character representation. The
5342 character representation is replaced with the octal escape @samp{\nnn}
5343 for characters outside the 7-bit @sc{ascii} range.
5346 Regard the bits of the value as a floating point number and print
5347 using typical floating point syntax.
5350 For example, to print the program counter in hex (@pxref{Registers}), type
5357 Note that no space is required before the slash; this is because command
5358 names in @value{GDBN} cannot contain a slash.
5360 To reprint the last value in the value history with a different format,
5361 you can use the @code{print} command with just a format and no
5362 expression. For example, @samp{p/x} reprints the last value in hex.
5365 @section Examining memory
5367 You can use the command @code{x} (for ``examine'') to examine memory in
5368 any of several formats, independently of your program's data types.
5370 @cindex examining memory
5372 @kindex x @r{(examine memory)}
5373 @item x/@var{nfu} @var{addr}
5376 Use the @code{x} command to examine memory.
5379 @var{n}, @var{f}, and @var{u} are all optional parameters that specify how
5380 much memory to display and how to format it; @var{addr} is an
5381 expression giving the address where you want to start displaying memory.
5382 If you use defaults for @var{nfu}, you need not type the slash @samp{/}.
5383 Several commands set convenient defaults for @var{addr}.
5386 @item @var{n}, the repeat count
5387 The repeat count is a decimal integer; the default is 1. It specifies
5388 how much memory (counting by units @var{u}) to display.
5389 @c This really is **decimal**; unaffected by 'set radix' as of GDB
5392 @item @var{f}, the display format
5393 The display format is one of the formats used by @code{print}
5394 (@samp{x}, @samp{d}, @samp{u}, @samp{o}, @samp{t}, @samp{a}, @samp{c},
5395 @samp{f}), and in addition @samp{s} (for null-terminated strings) and
5396 @samp{i} (for machine instructions). The default is @samp{x}
5397 (hexadecimal) initially. The default changes each time you use either
5398 @code{x} or @code{print}.
5400 @item @var{u}, the unit size
5401 The unit size is any of
5407 Halfwords (two bytes).
5409 Words (four bytes). This is the initial default.
5411 Giant words (eight bytes).
5414 Each time you specify a unit size with @code{x}, that size becomes the
5415 default unit the next time you use @code{x}. (For the @samp{s} and
5416 @samp{i} formats, the unit size is ignored and is normally not written.)
5418 @item @var{addr}, starting display address
5419 @var{addr} is the address where you want @value{GDBN} to begin displaying
5420 memory. The expression need not have a pointer value (though it may);
5421 it is always interpreted as an integer address of a byte of memory.
5422 @xref{Expressions, ,Expressions}, for more information on expressions. The default for
5423 @var{addr} is usually just after the last address examined---but several
5424 other commands also set the default address: @code{info breakpoints} (to
5425 the address of the last breakpoint listed), @code{info line} (to the
5426 starting address of a line), and @code{print} (if you use it to display
5427 a value from memory).
5430 For example, @samp{x/3uh 0x54320} is a request to display three halfwords
5431 (@code{h}) of memory, formatted as unsigned decimal integers (@samp{u}),
5432 starting at address @code{0x54320}. @samp{x/4xw $sp} prints the four
5433 words (@samp{w}) of memory above the stack pointer (here, @samp{$sp};
5434 @pxref{Registers, ,Registers}) in hexadecimal (@samp{x}).
5436 Since the letters indicating unit sizes are all distinct from the
5437 letters specifying output formats, you do not have to remember whether
5438 unit size or format comes first; either order works. The output
5439 specifications @samp{4xw} and @samp{4wx} mean exactly the same thing.
5440 (However, the count @var{n} must come first; @samp{wx4} does not work.)
5442 Even though the unit size @var{u} is ignored for the formats @samp{s}
5443 and @samp{i}, you might still want to use a count @var{n}; for example,
5444 @samp{3i} specifies that you want to see three machine instructions,
5445 including any operands. The command @code{disassemble} gives an
5446 alternative way of inspecting machine instructions; see @ref{Machine
5447 Code,,Source and machine code}.
5449 All the defaults for the arguments to @code{x} are designed to make it
5450 easy to continue scanning memory with minimal specifications each time
5451 you use @code{x}. For example, after you have inspected three machine
5452 instructions with @samp{x/3i @var{addr}}, you can inspect the next seven
5453 with just @samp{x/7}. If you use @key{RET} to repeat the @code{x} command,
5454 the repeat count @var{n} is used again; the other arguments default as
5455 for successive uses of @code{x}.
5457 @cindex @code{$_}, @code{$__}, and value history
5458 The addresses and contents printed by the @code{x} command are not saved
5459 in the value history because there is often too much of them and they
5460 would get in the way. Instead, @value{GDBN} makes these values available for
5461 subsequent use in expressions as values of the convenience variables
5462 @code{$_} and @code{$__}. After an @code{x} command, the last address
5463 examined is available for use in expressions in the convenience variable
5464 @code{$_}. The contents of that address, as examined, are available in
5465 the convenience variable @code{$__}.
5467 If the @code{x} command has a repeat count, the address and contents saved
5468 are from the last memory unit printed; this is not the same as the last
5469 address printed if several units were printed on the last line of output.
5471 @cindex remote memory comparison
5472 @cindex verify remote memory image
5473 When you are debugging a program running on a remote target machine
5474 (@pxref{Remote}), you may wish to verify the program's image in the
5475 remote machine's memory against the executable file you downloaded to
5476 the target. The @code{compare-sections} command is provided for such
5480 @kindex compare-sections
5481 @item compare-sections @r{[}@var{section-name}@r{]}
5482 Compare the data of a loadable section @var{section-name} in the
5483 executable file of the program being debugged with the same section in
5484 the remote machine's memory, and report any mismatches. With no
5485 arguments, compares all loadable sections. This command's
5486 availability depends on the target's support for the @code{"qCRC"}
5491 @section Automatic display
5492 @cindex automatic display
5493 @cindex display of expressions
5495 If you find that you want to print the value of an expression frequently
5496 (to see how it changes), you might want to add it to the @dfn{automatic
5497 display list} so that @value{GDBN} prints its value each time your program stops.
5498 Each expression added to the list is given a number to identify it;
5499 to remove an expression from the list, you specify that number.
5500 The automatic display looks like this:
5504 3: bar[5] = (struct hack *) 0x3804
5508 This display shows item numbers, expressions and their current values. As with
5509 displays you request manually using @code{x} or @code{print}, you can
5510 specify the output format you prefer; in fact, @code{display} decides
5511 whether to use @code{print} or @code{x} depending on how elaborate your
5512 format specification is---it uses @code{x} if you specify a unit size,
5513 or one of the two formats (@samp{i} and @samp{s}) that are only
5514 supported by @code{x}; otherwise it uses @code{print}.
5518 @item display @var{expr}
5519 Add the expression @var{expr} to the list of expressions to display
5520 each time your program stops. @xref{Expressions, ,Expressions}.
5522 @code{display} does not repeat if you press @key{RET} again after using it.
5524 @item display/@var{fmt} @var{expr}
5525 For @var{fmt} specifying only a display format and not a size or
5526 count, add the expression @var{expr} to the auto-display list but
5527 arrange to display it each time in the specified format @var{fmt}.
5528 @xref{Output Formats,,Output formats}.
5530 @item display/@var{fmt} @var{addr}
5531 For @var{fmt} @samp{i} or @samp{s}, or including a unit-size or a
5532 number of units, add the expression @var{addr} as a memory address to
5533 be examined each time your program stops. Examining means in effect
5534 doing @samp{x/@var{fmt} @var{addr}}. @xref{Memory, ,Examining memory}.
5537 For example, @samp{display/i $pc} can be helpful, to see the machine
5538 instruction about to be executed each time execution stops (@samp{$pc}
5539 is a common name for the program counter; @pxref{Registers, ,Registers}).
5542 @kindex delete display
5544 @item undisplay @var{dnums}@dots{}
5545 @itemx delete display @var{dnums}@dots{}
5546 Remove item numbers @var{dnums} from the list of expressions to display.
5548 @code{undisplay} does not repeat if you press @key{RET} after using it.
5549 (Otherwise you would just get the error @samp{No display number @dots{}}.)
5551 @kindex disable display
5552 @item disable display @var{dnums}@dots{}
5553 Disable the display of item numbers @var{dnums}. A disabled display
5554 item is not printed automatically, but is not forgotten. It may be
5555 enabled again later.
5557 @kindex enable display
5558 @item enable display @var{dnums}@dots{}
5559 Enable display of item numbers @var{dnums}. It becomes effective once
5560 again in auto display of its expression, until you specify otherwise.
5563 Display the current values of the expressions on the list, just as is
5564 done when your program stops.
5566 @kindex info display
5568 Print the list of expressions previously set up to display
5569 automatically, each one with its item number, but without showing the
5570 values. This includes disabled expressions, which are marked as such.
5571 It also includes expressions which would not be displayed right now
5572 because they refer to automatic variables not currently available.
5575 @cindex display disabled out of scope
5576 If a display expression refers to local variables, then it does not make
5577 sense outside the lexical context for which it was set up. Such an
5578 expression is disabled when execution enters a context where one of its
5579 variables is not defined. For example, if you give the command
5580 @code{display last_char} while inside a function with an argument
5581 @code{last_char}, @value{GDBN} displays this argument while your program
5582 continues to stop inside that function. When it stops elsewhere---where
5583 there is no variable @code{last_char}---the display is disabled
5584 automatically. The next time your program stops where @code{last_char}
5585 is meaningful, you can enable the display expression once again.
5587 @node Print Settings
5588 @section Print settings
5590 @cindex format options
5591 @cindex print settings
5592 @value{GDBN} provides the following ways to control how arrays, structures,
5593 and symbols are printed.
5596 These settings are useful for debugging programs in any language:
5600 @item set print address
5601 @itemx set print address on
5602 @cindex print/don't print memory addresses
5603 @value{GDBN} prints memory addresses showing the location of stack
5604 traces, structure values, pointer values, breakpoints, and so forth,
5605 even when it also displays the contents of those addresses. The default
5606 is @code{on}. For example, this is what a stack frame display looks like with
5607 @code{set print address on}:
5612 #0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>")
5614 530 if (lquote != def_lquote)
5618 @item set print address off
5619 Do not print addresses when displaying their contents. For example,
5620 this is the same stack frame displayed with @code{set print address off}:
5624 (@value{GDBP}) set print addr off
5626 #0 set_quotes (lq="<<", rq=">>") at input.c:530
5627 530 if (lquote != def_lquote)
5631 You can use @samp{set print address off} to eliminate all machine
5632 dependent displays from the @value{GDBN} interface. For example, with
5633 @code{print address off}, you should get the same text for backtraces on
5634 all machines---whether or not they involve pointer arguments.
5637 @item show print address
5638 Show whether or not addresses are to be printed.
5641 When @value{GDBN} prints a symbolic address, it normally prints the
5642 closest earlier symbol plus an offset. If that symbol does not uniquely
5643 identify the address (for example, it is a name whose scope is a single
5644 source file), you may need to clarify. One way to do this is with
5645 @code{info line}, for example @samp{info line *0x4537}. Alternately,
5646 you can set @value{GDBN} to print the source file and line number when
5647 it prints a symbolic address:
5650 @item set print symbol-filename on
5651 @cindex source file and line of a symbol
5652 @cindex symbol, source file and line
5653 Tell @value{GDBN} to print the source file name and line number of a
5654 symbol in the symbolic form of an address.
5656 @item set print symbol-filename off
5657 Do not print source file name and line number of a symbol. This is the
5660 @item show print symbol-filename
5661 Show whether or not @value{GDBN} will print the source file name and
5662 line number of a symbol in the symbolic form of an address.
5665 Another situation where it is helpful to show symbol filenames and line
5666 numbers is when disassembling code; @value{GDBN} shows you the line
5667 number and source file that corresponds to each instruction.
5669 Also, you may wish to see the symbolic form only if the address being
5670 printed is reasonably close to the closest earlier symbol:
5673 @item set print max-symbolic-offset @var{max-offset}
5674 @cindex maximum value for offset of closest symbol
5675 Tell @value{GDBN} to only display the symbolic form of an address if the
5676 offset between the closest earlier symbol and the address is less than
5677 @var{max-offset}. The default is 0, which tells @value{GDBN}
5678 to always print the symbolic form of an address if any symbol precedes it.
5680 @item show print max-symbolic-offset
5681 Ask how large the maximum offset is that @value{GDBN} prints in a
5685 @cindex wild pointer, interpreting
5686 @cindex pointer, finding referent
5687 If you have a pointer and you are not sure where it points, try
5688 @samp{set print symbol-filename on}. Then you can determine the name
5689 and source file location of the variable where it points, using
5690 @samp{p/a @var{pointer}}. This interprets the address in symbolic form.
5691 For example, here @value{GDBN} shows that a variable @code{ptt} points
5692 at another variable @code{t}, defined in @file{hi2.c}:
5695 (@value{GDBP}) set print symbol-filename on
5696 (@value{GDBP}) p/a ptt
5697 $4 = 0xe008 <t in hi2.c>
5701 @emph{Warning:} For pointers that point to a local variable, @samp{p/a}
5702 does not show the symbol name and filename of the referent, even with
5703 the appropriate @code{set print} options turned on.
5706 Other settings control how different kinds of objects are printed:
5709 @item set print array
5710 @itemx set print array on
5711 @cindex pretty print arrays
5712 Pretty print arrays. This format is more convenient to read,
5713 but uses more space. The default is off.
5715 @item set print array off
5716 Return to compressed format for arrays.
5718 @item show print array
5719 Show whether compressed or pretty format is selected for displaying
5722 @item set print elements @var{number-of-elements}
5723 @cindex number of array elements to print
5724 @cindex limit on number of printed array elements
5725 Set a limit on how many elements of an array @value{GDBN} will print.
5726 If @value{GDBN} is printing a large array, it stops printing after it has
5727 printed the number of elements set by the @code{set print elements} command.
5728 This limit also applies to the display of strings.
5729 When @value{GDBN} starts, this limit is set to 200.
5730 Setting @var{number-of-elements} to zero means that the printing is unlimited.
5732 @item show print elements
5733 Display the number of elements of a large array that @value{GDBN} will print.
5734 If the number is 0, then the printing is unlimited.
5736 @item set print repeats
5737 @cindex repeated array elements
5738 Set the threshold for suppressing display of repeated array
5739 elelments. When the number of consecutive identical elements of an
5740 array exceeds the threshold, @value{GDBN} prints the string
5741 @code{"<repeats @var{n} times>"}, where @var{n} is the number of
5742 identical repetitions, instead of displaying the identical elements
5743 themselves. Setting the threshold to zero will cause all elements to
5744 be individually printed. The default threshold is 10.
5746 @item show print repeats
5747 Display the current threshold for printing repeated identical
5750 @item set print null-stop
5751 @cindex @sc{null} elements in arrays
5752 Cause @value{GDBN} to stop printing the characters of an array when the first
5753 @sc{null} is encountered. This is useful when large arrays actually
5754 contain only short strings.
5757 @item show print null-stop
5758 Show whether @value{GDBN} stops printing an array on the first
5759 @sc{null} character.
5761 @item set print pretty on
5762 @cindex print structures in indented form
5763 @cindex indentation in structure display
5764 Cause @value{GDBN} to print structures in an indented format with one member
5765 per line, like this:
5780 @item set print pretty off
5781 Cause @value{GDBN} to print structures in a compact format, like this:
5785 $1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, \
5786 meat = 0x54 "Pork"@}
5791 This is the default format.
5793 @item show print pretty
5794 Show which format @value{GDBN} is using to print structures.
5796 @item set print sevenbit-strings on
5797 @cindex eight-bit characters in strings
5798 @cindex octal escapes in strings
5799 Print using only seven-bit characters; if this option is set,
5800 @value{GDBN} displays any eight-bit characters (in strings or
5801 character values) using the notation @code{\}@var{nnn}. This setting is
5802 best if you are working in English (@sc{ascii}) and you use the
5803 high-order bit of characters as a marker or ``meta'' bit.
5805 @item set print sevenbit-strings off
5806 Print full eight-bit characters. This allows the use of more
5807 international character sets, and is the default.
5809 @item show print sevenbit-strings
5810 Show whether or not @value{GDBN} is printing only seven-bit characters.
5812 @item set print union on
5813 @cindex unions in structures, printing
5814 Tell @value{GDBN} to print unions which are contained in structures
5815 and other unions. This is the default setting.
5817 @item set print union off
5818 Tell @value{GDBN} not to print unions which are contained in
5819 structures and other unions. @value{GDBN} will print @code{"@{...@}"}
5822 @item show print union
5823 Ask @value{GDBN} whether or not it will print unions which are contained in
5824 structures and other unions.
5826 For example, given the declarations
5829 typedef enum @{Tree, Bug@} Species;
5830 typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms;
5831 typedef enum @{Caterpillar, Cocoon, Butterfly@}
5842 struct thing foo = @{Tree, @{Acorn@}@};
5846 with @code{set print union on} in effect @samp{p foo} would print
5849 $1 = @{it = Tree, form = @{tree = Acorn, bug = Cocoon@}@}
5853 and with @code{set print union off} in effect it would print
5856 $1 = @{it = Tree, form = @{...@}@}
5860 @code{set print union} affects programs written in C-like languages
5866 These settings are of interest when debugging C@t{++} programs:
5869 @cindex demangling C@t{++} names
5870 @item set print demangle
5871 @itemx set print demangle on
5872 Print C@t{++} names in their source form rather than in the encoded
5873 (``mangled'') form passed to the assembler and linker for type-safe
5874 linkage. The default is on.
5876 @item show print demangle
5877 Show whether C@t{++} names are printed in mangled or demangled form.
5879 @item set print asm-demangle
5880 @itemx set print asm-demangle on
5881 Print C@t{++} names in their source form rather than their mangled form, even
5882 in assembler code printouts such as instruction disassemblies.
5885 @item show print asm-demangle
5886 Show whether C@t{++} names in assembly listings are printed in mangled
5889 @cindex C@t{++} symbol decoding style
5890 @cindex symbol decoding style, C@t{++}
5891 @kindex set demangle-style
5892 @item set demangle-style @var{style}
5893 Choose among several encoding schemes used by different compilers to
5894 represent C@t{++} names. The choices for @var{style} are currently:
5898 Allow @value{GDBN} to choose a decoding style by inspecting your program.
5901 Decode based on the @sc{gnu} C@t{++} compiler (@code{g++}) encoding algorithm.
5902 This is the default.
5905 Decode based on the HP ANSI C@t{++} (@code{aCC}) encoding algorithm.
5908 Decode based on the Lucid C@t{++} compiler (@code{lcc}) encoding algorithm.
5911 Decode using the algorithm in the @cite{C@t{++} Annotated Reference Manual}.
5912 @strong{Warning:} this setting alone is not sufficient to allow
5913 debugging @code{cfront}-generated executables. @value{GDBN} would
5914 require further enhancement to permit that.
5917 If you omit @var{style}, you will see a list of possible formats.
5919 @item show demangle-style
5920 Display the encoding style currently in use for decoding C@t{++} symbols.
5922 @item set print object
5923 @itemx set print object on
5924 @cindex derived type of an object, printing
5925 @cindex display derived types
5926 When displaying a pointer to an object, identify the @emph{actual}
5927 (derived) type of the object rather than the @emph{declared} type, using
5928 the virtual function table.
5930 @item set print object off
5931 Display only the declared type of objects, without reference to the
5932 virtual function table. This is the default setting.
5934 @item show print object
5935 Show whether actual, or declared, object types are displayed.
5937 @item set print static-members
5938 @itemx set print static-members on
5939 @cindex static members of C@t{++} objects
5940 Print static members when displaying a C@t{++} object. The default is on.
5942 @item set print static-members off
5943 Do not print static members when displaying a C@t{++} object.
5945 @item show print static-members
5946 Show whether C@t{++} static members are printed or not.
5948 @item set print pascal_static-members
5949 @itemx set print pascal_static-members on
5950 @cindex static members of Pacal objects
5951 @cindex Pacal objects, static members display
5952 Print static members when displaying a Pascal object. The default is on.
5954 @item set print pascal_static-members off
5955 Do not print static members when displaying a Pascal object.
5957 @item show print pascal_static-members
5958 Show whether Pascal static members are printed or not.
5960 @c These don't work with HP ANSI C++ yet.
5961 @item set print vtbl
5962 @itemx set print vtbl on
5963 @cindex pretty print C@t{++} virtual function tables
5964 @cindex virtual functions (C@t{++}) display
5965 @cindex VTBL display
5966 Pretty print C@t{++} virtual function tables. The default is off.
5967 (The @code{vtbl} commands do not work on programs compiled with the HP
5968 ANSI C@t{++} compiler (@code{aCC}).)
5970 @item set print vtbl off
5971 Do not pretty print C@t{++} virtual function tables.
5973 @item show print vtbl
5974 Show whether C@t{++} virtual function tables are pretty printed, or not.
5978 @section Value history
5980 @cindex value history
5981 @cindex history of values printed by @value{GDBN}
5982 Values printed by the @code{print} command are saved in the @value{GDBN}
5983 @dfn{value history}. This allows you to refer to them in other expressions.
5984 Values are kept until the symbol table is re-read or discarded
5985 (for example with the @code{file} or @code{symbol-file} commands).
5986 When the symbol table changes, the value history is discarded,
5987 since the values may contain pointers back to the types defined in the
5992 @cindex history number
5993 The values printed are given @dfn{history numbers} by which you can
5994 refer to them. These are successive integers starting with one.
5995 @code{print} shows you the history number assigned to a value by
5996 printing @samp{$@var{num} = } before the value; here @var{num} is the
5999 To refer to any previous value, use @samp{$} followed by the value's
6000 history number. The way @code{print} labels its output is designed to
6001 remind you of this. Just @code{$} refers to the most recent value in
6002 the history, and @code{$$} refers to the value before that.
6003 @code{$$@var{n}} refers to the @var{n}th value from the end; @code{$$2}
6004 is the value just prior to @code{$$}, @code{$$1} is equivalent to
6005 @code{$$}, and @code{$$0} is equivalent to @code{$}.
6007 For example, suppose you have just printed a pointer to a structure and
6008 want to see the contents of the structure. It suffices to type
6014 If you have a chain of structures where the component @code{next} points
6015 to the next one, you can print the contents of the next one with this:
6022 You can print successive links in the chain by repeating this
6023 command---which you can do by just typing @key{RET}.
6025 Note that the history records values, not expressions. If the value of
6026 @code{x} is 4 and you type these commands:
6034 then the value recorded in the value history by the @code{print} command
6035 remains 4 even though the value of @code{x} has changed.
6040 Print the last ten values in the value history, with their item numbers.
6041 This is like @samp{p@ $$9} repeated ten times, except that @code{show
6042 values} does not change the history.
6044 @item show values @var{n}
6045 Print ten history values centered on history item number @var{n}.
6048 Print ten history values just after the values last printed. If no more
6049 values are available, @code{show values +} produces no display.
6052 Pressing @key{RET} to repeat @code{show values @var{n}} has exactly the
6053 same effect as @samp{show values +}.
6055 @node Convenience Vars
6056 @section Convenience variables
6058 @cindex convenience variables
6059 @cindex user-defined variables
6060 @value{GDBN} provides @dfn{convenience variables} that you can use within
6061 @value{GDBN} to hold on to a value and refer to it later. These variables
6062 exist entirely within @value{GDBN}; they are not part of your program, and
6063 setting a convenience variable has no direct effect on further execution
6064 of your program. That is why you can use them freely.
6066 Convenience variables are prefixed with @samp{$}. Any name preceded by
6067 @samp{$} can be used for a convenience variable, unless it is one of
6068 the predefined machine-specific register names (@pxref{Registers, ,Registers}).
6069 (Value history references, in contrast, are @emph{numbers} preceded
6070 by @samp{$}. @xref{Value History, ,Value history}.)
6072 You can save a value in a convenience variable with an assignment
6073 expression, just as you would set a variable in your program.
6077 set $foo = *object_ptr
6081 would save in @code{$foo} the value contained in the object pointed to by
6084 Using a convenience variable for the first time creates it, but its
6085 value is @code{void} until you assign a new value. You can alter the
6086 value with another assignment at any time.
6088 Convenience variables have no fixed types. You can assign a convenience
6089 variable any type of value, including structures and arrays, even if
6090 that variable already has a value of a different type. The convenience
6091 variable, when used as an expression, has the type of its current value.
6094 @kindex show convenience
6095 @cindex show all user variables
6096 @item show convenience
6097 Print a list of convenience variables used so far, and their values.
6098 Abbreviated @code{show conv}.
6101 One of the ways to use a convenience variable is as a counter to be
6102 incremented or a pointer to be advanced. For example, to print
6103 a field from successive elements of an array of structures:
6107 print bar[$i++]->contents
6111 Repeat that command by typing @key{RET}.
6113 Some convenience variables are created automatically by @value{GDBN} and given
6114 values likely to be useful.
6117 @vindex $_@r{, convenience variable}
6119 The variable @code{$_} is automatically set by the @code{x} command to
6120 the last address examined (@pxref{Memory, ,Examining memory}). Other
6121 commands which provide a default address for @code{x} to examine also
6122 set @code{$_} to that address; these commands include @code{info line}
6123 and @code{info breakpoint}. The type of @code{$_} is @code{void *}
6124 except when set by the @code{x} command, in which case it is a pointer
6125 to the type of @code{$__}.
6127 @vindex $__@r{, convenience variable}
6129 The variable @code{$__} is automatically set by the @code{x} command
6130 to the value found in the last address examined. Its type is chosen
6131 to match the format in which the data was printed.
6134 @vindex $_exitcode@r{, convenience variable}
6135 The variable @code{$_exitcode} is automatically set to the exit code when
6136 the program being debugged terminates.
6139 On HP-UX systems, if you refer to a function or variable name that
6140 begins with a dollar sign, @value{GDBN} searches for a user or system
6141 name first, before it searches for a convenience variable.
6147 You can refer to machine register contents, in expressions, as variables
6148 with names starting with @samp{$}. The names of registers are different
6149 for each machine; use @code{info registers} to see the names used on
6153 @kindex info registers
6154 @item info registers
6155 Print the names and values of all registers except floating-point
6156 and vector registers (in the selected stack frame).
6158 @kindex info all-registers
6159 @cindex floating point registers
6160 @item info all-registers
6161 Print the names and values of all registers, including floating-point
6162 and vector registers (in the selected stack frame).
6164 @item info registers @var{regname} @dots{}
6165 Print the @dfn{relativized} value of each specified register @var{regname}.
6166 As discussed in detail below, register values are normally relative to
6167 the selected stack frame. @var{regname} may be any register name valid on
6168 the machine you are using, with or without the initial @samp{$}.
6171 @cindex stack pointer register
6172 @cindex program counter register
6173 @cindex process status register
6174 @cindex frame pointer register
6175 @cindex standard registers
6176 @value{GDBN} has four ``standard'' register names that are available (in
6177 expressions) on most machines---whenever they do not conflict with an
6178 architecture's canonical mnemonics for registers. The register names
6179 @code{$pc} and @code{$sp} are used for the program counter register and
6180 the stack pointer. @code{$fp} is used for a register that contains a
6181 pointer to the current stack frame, and @code{$ps} is used for a
6182 register that contains the processor status. For example,
6183 you could print the program counter in hex with
6190 or print the instruction to be executed next with
6197 or add four to the stack pointer@footnote{This is a way of removing
6198 one word from the stack, on machines where stacks grow downward in
6199 memory (most machines, nowadays). This assumes that the innermost
6200 stack frame is selected; setting @code{$sp} is not allowed when other
6201 stack frames are selected. To pop entire frames off the stack,
6202 regardless of machine architecture, use @code{return};
6203 see @ref{Returning, ,Returning from a function}.} with
6209 Whenever possible, these four standard register names are available on
6210 your machine even though the machine has different canonical mnemonics,
6211 so long as there is no conflict. The @code{info registers} command
6212 shows the canonical names. For example, on the SPARC, @code{info
6213 registers} displays the processor status register as @code{$psr} but you
6214 can also refer to it as @code{$ps}; and on x86-based machines @code{$ps}
6215 is an alias for the @sc{eflags} register.
6217 @value{GDBN} always considers the contents of an ordinary register as an
6218 integer when the register is examined in this way. Some machines have
6219 special registers which can hold nothing but floating point; these
6220 registers are considered to have floating point values. There is no way
6221 to refer to the contents of an ordinary register as floating point value
6222 (although you can @emph{print} it as a floating point value with
6223 @samp{print/f $@var{regname}}).
6225 Some registers have distinct ``raw'' and ``virtual'' data formats. This
6226 means that the data format in which the register contents are saved by
6227 the operating system is not the same one that your program normally
6228 sees. For example, the registers of the 68881 floating point
6229 coprocessor are always saved in ``extended'' (raw) format, but all C
6230 programs expect to work with ``double'' (virtual) format. In such
6231 cases, @value{GDBN} normally works with the virtual format only (the format
6232 that makes sense for your program), but the @code{info registers} command
6233 prints the data in both formats.
6235 Normally, register values are relative to the selected stack frame
6236 (@pxref{Selection, ,Selecting a frame}). This means that you get the
6237 value that the register would contain if all stack frames farther in
6238 were exited and their saved registers restored. In order to see the
6239 true contents of hardware registers, you must select the innermost
6240 frame (with @samp{frame 0}).
6242 However, @value{GDBN} must deduce where registers are saved, from the machine
6243 code generated by your compiler. If some registers are not saved, or if
6244 @value{GDBN} is unable to locate the saved registers, the selected stack
6245 frame makes no difference.
6247 @node Floating Point Hardware
6248 @section Floating point hardware
6249 @cindex floating point
6251 Depending on the configuration, @value{GDBN} may be able to give
6252 you more information about the status of the floating point hardware.
6257 Display hardware-dependent information about the floating
6258 point unit. The exact contents and layout vary depending on the
6259 floating point chip. Currently, @samp{info float} is supported on
6260 the ARM and x86 machines.
6264 @section Vector Unit
6267 Depending on the configuration, @value{GDBN} may be able to give you
6268 more information about the status of the vector unit.
6273 Display information about the vector unit. The exact contents and
6274 layout vary depending on the hardware.
6277 @node OS Information
6278 @section Operating system auxiliary information
6279 @cindex OS information
6281 @value{GDBN} provides interfaces to useful OS facilities that can help
6282 you debug your program.
6284 @cindex @code{ptrace} system call
6285 @cindex @code{struct user} contents
6286 When @value{GDBN} runs on a @dfn{Posix system} (such as GNU or Unix
6287 machines), it interfaces with the inferior via the @code{ptrace}
6288 system call. The operating system creates a special sata structure,
6289 called @code{struct user}, for this interface. You can use the
6290 command @code{info udot} to display the contents of this data
6296 Display the contents of the @code{struct user} maintained by the OS
6297 kernel for the program being debugged. @value{GDBN} displays the
6298 contents of @code{struct user} as a list of hex numbers, similar to
6299 the @code{examine} command.
6302 @cindex auxiliary vector
6303 @cindex vector, auxiliary
6304 Some operating systems supply an @dfn{auxiliary vector} to programs at
6305 startup. This is akin to the arguments and environment that you
6306 specify for a program, but contains a system-dependent variety of
6307 binary values that tell system libraries important details about the
6308 hardware, operating system, and process. Each value's purpose is
6309 identified by an integer tag; the meanings are well-known but system-specific.
6310 Depending on the configuration and operating system facilities,
6311 @value{GDBN} may be able to show you this information. For remote
6312 targets, this functionality may further depend on the remote stub's
6313 support of the @samp{qPart:auxv:read} packet, see @ref{Remote
6314 configuration, auxiliary vector}.
6319 Display the auxiliary vector of the inferior, which can be either a
6320 live process or a core dump file. @value{GDBN} prints each tag value
6321 numerically, and also shows names and text descriptions for recognized
6322 tags. Some values in the vector are numbers, some bit masks, and some
6323 pointers to strings or other data. @value{GDBN} displays each value in the
6324 most appropriate form for a recognized tag, and in hexadecimal for
6325 an unrecognized tag.
6329 @node Memory Region Attributes
6330 @section Memory region attributes
6331 @cindex memory region attributes
6333 @dfn{Memory region attributes} allow you to describe special handling
6334 required by regions of your target's memory. @value{GDBN} uses attributes
6335 to determine whether to allow certain types of memory accesses; whether to
6336 use specific width accesses; and whether to cache target memory.
6338 Defined memory regions can be individually enabled and disabled. When a
6339 memory region is disabled, @value{GDBN} uses the default attributes when
6340 accessing memory in that region. Similarly, if no memory regions have
6341 been defined, @value{GDBN} uses the default attributes when accessing
6344 When a memory region is defined, it is given a number to identify it;
6345 to enable, disable, or remove a memory region, you specify that number.
6349 @item mem @var{lower} @var{upper} @var{attributes}@dots{}
6350 Define a memory region bounded by @var{lower} and @var{upper} with
6351 attributes @var{attributes}@dots{}, and add it to the list of regions
6352 monitored by @value{GDBN}. Note that @var{upper} == 0 is a special
6353 case: it is treated as the the target's maximum memory address.
6354 (0xffff on 16 bit targets, 0xffffffff on 32 bit targets, etc.)
6357 @item delete mem @var{nums}@dots{}
6358 Remove memory regions @var{nums}@dots{} from the list of regions
6359 monitored by @value{GDBN}.
6362 @item disable mem @var{nums}@dots{}
6363 Disable monitoring of memory regions @var{nums}@dots{}.
6364 A disabled memory region is not forgotten.
6365 It may be enabled again later.
6368 @item enable mem @var{nums}@dots{}
6369 Enable monitoring of memory regions @var{nums}@dots{}.
6373 Print a table of all defined memory regions, with the following columns
6377 @item Memory Region Number
6378 @item Enabled or Disabled.
6379 Enabled memory regions are marked with @samp{y}.
6380 Disabled memory regions are marked with @samp{n}.
6383 The address defining the inclusive lower bound of the memory region.
6386 The address defining the exclusive upper bound of the memory region.
6389 The list of attributes set for this memory region.
6394 @subsection Attributes
6396 @subsubsection Memory Access Mode
6397 The access mode attributes set whether @value{GDBN} may make read or
6398 write accesses to a memory region.
6400 While these attributes prevent @value{GDBN} from performing invalid
6401 memory accesses, they do nothing to prevent the target system, I/O DMA,
6402 etc. from accessing memory.
6406 Memory is read only.
6408 Memory is write only.
6410 Memory is read/write. This is the default.
6413 @subsubsection Memory Access Size
6414 The acccess size attributes tells @value{GDBN} to use specific sized
6415 accesses in the memory region. Often memory mapped device registers
6416 require specific sized accesses. If no access size attribute is
6417 specified, @value{GDBN} may use accesses of any size.
6421 Use 8 bit memory accesses.
6423 Use 16 bit memory accesses.
6425 Use 32 bit memory accesses.
6427 Use 64 bit memory accesses.
6430 @c @subsubsection Hardware/Software Breakpoints
6431 @c The hardware/software breakpoint attributes set whether @value{GDBN}
6432 @c will use hardware or software breakpoints for the internal breakpoints
6433 @c used by the step, next, finish, until, etc. commands.
6437 @c Always use hardware breakpoints
6438 @c @item swbreak (default)
6441 @subsubsection Data Cache
6442 The data cache attributes set whether @value{GDBN} will cache target
6443 memory. While this generally improves performance by reducing debug
6444 protocol overhead, it can lead to incorrect results because @value{GDBN}
6445 does not know about volatile variables or memory mapped device
6450 Enable @value{GDBN} to cache target memory.
6452 Disable @value{GDBN} from caching target memory. This is the default.
6455 @c @subsubsection Memory Write Verification
6456 @c The memory write verification attributes set whether @value{GDBN}
6457 @c will re-reads data after each write to verify the write was successful.
6461 @c @item noverify (default)
6464 @node Dump/Restore Files
6465 @section Copy between memory and a file
6466 @cindex dump/restore files
6467 @cindex append data to a file
6468 @cindex dump data to a file
6469 @cindex restore data from a file
6471 You can use the commands @code{dump}, @code{append}, and
6472 @code{restore} to copy data between target memory and a file. The
6473 @code{dump} and @code{append} commands write data to a file, and the
6474 @code{restore} command reads data from a file back into the inferior's
6475 memory. Files may be in binary, Motorola S-record, Intel hex, or
6476 Tektronix Hex format; however, @value{GDBN} can only append to binary
6482 @item dump @r{[}@var{format}@r{]} memory @var{filename} @var{start_addr} @var{end_addr}
6483 @itemx dump @r{[}@var{format}@r{]} value @var{filename} @var{expr}
6484 Dump the contents of memory from @var{start_addr} to @var{end_addr},
6485 or the value of @var{expr}, to @var{filename} in the given format.
6487 The @var{format} parameter may be any one of:
6494 Motorola S-record format.
6496 Tektronix Hex format.
6499 @value{GDBN} uses the same definitions of these formats as the
6500 @sc{gnu} binary utilities, like @samp{objdump} and @samp{objcopy}. If
6501 @var{format} is omitted, @value{GDBN} dumps the data in raw binary
6505 @item append @r{[}binary@r{]} memory @var{filename} @var{start_addr} @var{end_addr}
6506 @itemx append @r{[}binary@r{]} value @var{filename} @var{expr}
6507 Append the contents of memory from @var{start_addr} to @var{end_addr},
6508 or the value of @var{expr}, to the file @var{filename}, in raw binary form.
6509 (@value{GDBN} can only append data to files in raw binary form.)
6512 @item restore @var{filename} @r{[}binary@r{]} @var{bias} @var{start} @var{end}
6513 Restore the contents of file @var{filename} into memory. The
6514 @code{restore} command can automatically recognize any known @sc{bfd}
6515 file format, except for raw binary. To restore a raw binary file you
6516 must specify the optional keyword @code{binary} after the filename.
6518 If @var{bias} is non-zero, its value will be added to the addresses
6519 contained in the file. Binary files always start at address zero, so
6520 they will be restored at address @var{bias}. Other bfd files have
6521 a built-in location; they will be restored at offset @var{bias}
6524 If @var{start} and/or @var{end} are non-zero, then only data between
6525 file offset @var{start} and file offset @var{end} will be restored.
6526 These offsets are relative to the addresses in the file, before
6527 the @var{bias} argument is applied.
6531 @node Core File Generation
6532 @section How to Produce a Core File from Your Program
6533 @cindex dump core from inferior
6535 A @dfn{core file} or @dfn{core dump} is a file that records the memory
6536 image of a running process and its process status (register values
6537 etc.). Its primary use is post-mortem debugging of a program that
6538 crashed while it ran outside a debugger. A program that crashes
6539 automatically produces a core file, unless this feature is disabled by
6540 the user. @xref{Files}, for information on invoking @value{GDBN} in
6541 the post-mortem debugging mode.
6543 Occasionally, you may wish to produce a core file of the program you
6544 are debugging in order to preserve a snapshot of its state.
6545 @value{GDBN} has a special command for that.
6549 @kindex generate-core-file
6550 @item generate-core-file [@var{file}]
6551 @itemx gcore [@var{file}]
6552 Produce a core dump of the inferior process. The optional argument
6553 @var{file} specifies the file name where to put the core dump. If not
6554 specified, the file name defaults to @file{core.@var{pid}}, where
6555 @var{pid} is the inferior process ID.
6557 Note that this command is implemented only for some systems (as of
6558 this writing, @sc{gnu}/Linux, FreeBSD, Solaris, Unixware, and S390).
6561 @node Character Sets
6562 @section Character Sets
6563 @cindex character sets
6565 @cindex translating between character sets
6566 @cindex host character set
6567 @cindex target character set
6569 If the program you are debugging uses a different character set to
6570 represent characters and strings than the one @value{GDBN} uses itself,
6571 @value{GDBN} can automatically translate between the character sets for
6572 you. The character set @value{GDBN} uses we call the @dfn{host
6573 character set}; the one the inferior program uses we call the
6574 @dfn{target character set}.
6576 For example, if you are running @value{GDBN} on a @sc{gnu}/Linux system, which
6577 uses the ISO Latin 1 character set, but you are using @value{GDBN}'s
6578 remote protocol (@pxref{Remote,Remote Debugging}) to debug a program
6579 running on an IBM mainframe, which uses the @sc{ebcdic} character set,
6580 then the host character set is Latin-1, and the target character set is
6581 @sc{ebcdic}. If you give @value{GDBN} the command @code{set
6582 target-charset EBCDIC-US}, then @value{GDBN} translates between
6583 @sc{ebcdic} and Latin 1 as you print character or string values, or use
6584 character and string literals in expressions.
6586 @value{GDBN} has no way to automatically recognize which character set
6587 the inferior program uses; you must tell it, using the @code{set
6588 target-charset} command, described below.
6590 Here are the commands for controlling @value{GDBN}'s character set
6594 @item set target-charset @var{charset}
6595 @kindex set target-charset
6596 Set the current target character set to @var{charset}. We list the
6597 character set names @value{GDBN} recognizes below, but if you type
6598 @code{set target-charset} followed by @key{TAB}@key{TAB}, @value{GDBN} will
6599 list the target character sets it supports.
6603 @item set host-charset @var{charset}
6604 @kindex set host-charset
6605 Set the current host character set to @var{charset}.
6607 By default, @value{GDBN} uses a host character set appropriate to the
6608 system it is running on; you can override that default using the
6609 @code{set host-charset} command.
6611 @value{GDBN} can only use certain character sets as its host character
6612 set. We list the character set names @value{GDBN} recognizes below, and
6613 indicate which can be host character sets, but if you type
6614 @code{set target-charset} followed by @key{TAB}@key{TAB}, @value{GDBN} will
6615 list the host character sets it supports.
6617 @item set charset @var{charset}
6619 Set the current host and target character sets to @var{charset}. As
6620 above, if you type @code{set charset} followed by @key{TAB}@key{TAB},
6621 @value{GDBN} will list the name of the character sets that can be used
6622 for both host and target.
6626 @kindex show charset
6627 Show the names of the current host and target charsets.
6629 @itemx show host-charset
6630 @kindex show host-charset
6631 Show the name of the current host charset.
6633 @itemx show target-charset
6634 @kindex show target-charset
6635 Show the name of the current target charset.
6639 @value{GDBN} currently includes support for the following character
6645 @cindex ASCII character set
6646 Seven-bit U.S. @sc{ascii}. @value{GDBN} can use this as its host
6650 @cindex ISO 8859-1 character set
6651 @cindex ISO Latin 1 character set
6652 The ISO Latin 1 character set. This extends @sc{ascii} with accented
6653 characters needed for French, German, and Spanish. @value{GDBN} can use
6654 this as its host character set.
6658 @cindex EBCDIC character set
6659 @cindex IBM1047 character set
6660 Variants of the @sc{ebcdic} character set, used on some of IBM's
6661 mainframe operating systems. (@sc{gnu}/Linux on the S/390 uses U.S. @sc{ascii}.)
6662 @value{GDBN} cannot use these as its host character set.
6666 Note that these are all single-byte character sets. More work inside
6667 GDB is needed to support multi-byte or variable-width character
6668 encodings, like the UTF-8 and UCS-2 encodings of Unicode.
6670 Here is an example of @value{GDBN}'s character set support in action.
6671 Assume that the following source code has been placed in the file
6672 @file{charset-test.c}:
6678 = @{72, 101, 108, 108, 111, 44, 32, 119,
6679 111, 114, 108, 100, 33, 10, 0@};
6680 char ibm1047_hello[]
6681 = @{200, 133, 147, 147, 150, 107, 64, 166,
6682 150, 153, 147, 132, 90, 37, 0@};
6686 printf ("Hello, world!\n");
6690 In this program, @code{ascii_hello} and @code{ibm1047_hello} are arrays
6691 containing the string @samp{Hello, world!} followed by a newline,
6692 encoded in the @sc{ascii} and @sc{ibm1047} character sets.
6694 We compile the program, and invoke the debugger on it:
6697 $ gcc -g charset-test.c -o charset-test
6698 $ gdb -nw charset-test
6699 GNU gdb 2001-12-19-cvs
6700 Copyright 2001 Free Software Foundation, Inc.
6705 We can use the @code{show charset} command to see what character sets
6706 @value{GDBN} is currently using to interpret and display characters and
6710 (@value{GDBP}) show charset
6711 The current host and target character set is `ISO-8859-1'.
6715 For the sake of printing this manual, let's use @sc{ascii} as our
6716 initial character set:
6718 (@value{GDBP}) set charset ASCII
6719 (@value{GDBP}) show charset
6720 The current host and target character set is `ASCII'.
6724 Let's assume that @sc{ascii} is indeed the correct character set for our
6725 host system --- in other words, let's assume that if @value{GDBN} prints
6726 characters using the @sc{ascii} character set, our terminal will display
6727 them properly. Since our current target character set is also
6728 @sc{ascii}, the contents of @code{ascii_hello} print legibly:
6731 (@value{GDBP}) print ascii_hello
6732 $1 = 0x401698 "Hello, world!\n"
6733 (@value{GDBP}) print ascii_hello[0]
6738 @value{GDBN} uses the target character set for character and string
6739 literals you use in expressions:
6742 (@value{GDBP}) print '+'
6747 The @sc{ascii} character set uses the number 43 to encode the @samp{+}
6750 @value{GDBN} relies on the user to tell it which character set the
6751 target program uses. If we print @code{ibm1047_hello} while our target
6752 character set is still @sc{ascii}, we get jibberish:
6755 (@value{GDBP}) print ibm1047_hello
6756 $4 = 0x4016a8 "\310\205\223\223\226k@@\246\226\231\223\204Z%"
6757 (@value{GDBP}) print ibm1047_hello[0]
6762 If we invoke the @code{set target-charset} followed by @key{TAB}@key{TAB},
6763 @value{GDBN} tells us the character sets it supports:
6766 (@value{GDBP}) set target-charset
6767 ASCII EBCDIC-US IBM1047 ISO-8859-1
6768 (@value{GDBP}) set target-charset
6771 We can select @sc{ibm1047} as our target character set, and examine the
6772 program's strings again. Now the @sc{ascii} string is wrong, but
6773 @value{GDBN} translates the contents of @code{ibm1047_hello} from the
6774 target character set, @sc{ibm1047}, to the host character set,
6775 @sc{ascii}, and they display correctly:
6778 (@value{GDBP}) set target-charset IBM1047
6779 (@value{GDBP}) show charset
6780 The current host character set is `ASCII'.
6781 The current target character set is `IBM1047'.
6782 (@value{GDBP}) print ascii_hello
6783 $6 = 0x401698 "\110\145%%?\054\040\167?\162%\144\041\012"
6784 (@value{GDBP}) print ascii_hello[0]
6786 (@value{GDBP}) print ibm1047_hello
6787 $8 = 0x4016a8 "Hello, world!\n"
6788 (@value{GDBP}) print ibm1047_hello[0]
6793 As above, @value{GDBN} uses the target character set for character and
6794 string literals you use in expressions:
6797 (@value{GDBP}) print '+'
6802 The @sc{ibm1047} character set uses the number 78 to encode the @samp{+}
6805 @node Caching Remote Data
6806 @section Caching Data of Remote Targets
6807 @cindex caching data of remote targets
6809 @value{GDBN} can cache data exchanged between the debugger and a
6810 remote target (@pxref{Remote}). Such caching generally improves
6811 performance, because it reduces the overhead of the remote protocol by
6812 bundling memory reads and writes into large chunks. Unfortunately,
6813 @value{GDBN} does not currently know anything about volatile
6814 registers, and thus data caching will produce incorrect results when
6815 volatile registers are in use.
6818 @kindex set remotecache
6819 @item set remotecache on
6820 @itemx set remotecache off
6821 Set caching state for remote targets. When @code{ON}, use data
6822 caching. By default, this option is @code{OFF}.
6824 @kindex show remotecache
6825 @item show remotecache
6826 Show the current state of data caching for remote targets.
6830 Print the information about the data cache performance. The
6831 information displayed includes: the dcache width and depth; and for
6832 each cache line, how many times it was referenced, and its data and
6833 state (dirty, bad, ok, etc.). This command is useful for debugging
6834 the data cache operation.
6839 @chapter C Preprocessor Macros
6841 Some languages, such as C and C@t{++}, provide a way to define and invoke
6842 ``preprocessor macros'' which expand into strings of tokens.
6843 @value{GDBN} can evaluate expressions containing macro invocations, show
6844 the result of macro expansion, and show a macro's definition, including
6845 where it was defined.
6847 You may need to compile your program specially to provide @value{GDBN}
6848 with information about preprocessor macros. Most compilers do not
6849 include macros in their debugging information, even when you compile
6850 with the @option{-g} flag. @xref{Compilation}.
6852 A program may define a macro at one point, remove that definition later,
6853 and then provide a different definition after that. Thus, at different
6854 points in the program, a macro may have different definitions, or have
6855 no definition at all. If there is a current stack frame, @value{GDBN}
6856 uses the macros in scope at that frame's source code line. Otherwise,
6857 @value{GDBN} uses the macros in scope at the current listing location;
6860 At the moment, @value{GDBN} does not support the @code{##}
6861 token-splicing operator, the @code{#} stringification operator, or
6862 variable-arity macros.
6864 Whenever @value{GDBN} evaluates an expression, it always expands any
6865 macro invocations present in the expression. @value{GDBN} also provides
6866 the following commands for working with macros explicitly.
6870 @kindex macro expand
6871 @cindex macro expansion, showing the results of preprocessor
6872 @cindex preprocessor macro expansion, showing the results of
6873 @cindex expanding preprocessor macros
6874 @item macro expand @var{expression}
6875 @itemx macro exp @var{expression}
6876 Show the results of expanding all preprocessor macro invocations in
6877 @var{expression}. Since @value{GDBN} simply expands macros, but does
6878 not parse the result, @var{expression} need not be a valid expression;
6879 it can be any string of tokens.
6882 @item macro expand-once @var{expression}
6883 @itemx macro exp1 @var{expression}
6884 @cindex expand macro once
6885 @i{(This command is not yet implemented.)} Show the results of
6886 expanding those preprocessor macro invocations that appear explicitly in
6887 @var{expression}. Macro invocations appearing in that expansion are
6888 left unchanged. This command allows you to see the effect of a
6889 particular macro more clearly, without being confused by further
6890 expansions. Since @value{GDBN} simply expands macros, but does not
6891 parse the result, @var{expression} need not be a valid expression; it
6892 can be any string of tokens.
6895 @cindex macro definition, showing
6896 @cindex definition, showing a macro's
6897 @item info macro @var{macro}
6898 Show the definition of the macro named @var{macro}, and describe the
6899 source location where that definition was established.
6901 @kindex macro define
6902 @cindex user-defined macros
6903 @cindex defining macros interactively
6904 @cindex macros, user-defined
6905 @item macro define @var{macro} @var{replacement-list}
6906 @itemx macro define @var{macro}(@var{arglist}) @var{replacement-list}
6907 @i{(This command is not yet implemented.)} Introduce a definition for a
6908 preprocessor macro named @var{macro}, invocations of which are replaced
6909 by the tokens given in @var{replacement-list}. The first form of this
6910 command defines an ``object-like'' macro, which takes no arguments; the
6911 second form defines a ``function-like'' macro, which takes the arguments
6912 given in @var{arglist}.
6914 A definition introduced by this command is in scope in every expression
6915 evaluated in @value{GDBN}, until it is removed with the @command{macro
6916 undef} command, described below. The definition overrides all
6917 definitions for @var{macro} present in the program being debugged, as
6918 well as any previous user-supplied definition.
6921 @item macro undef @var{macro}
6922 @i{(This command is not yet implemented.)} Remove any user-supplied
6923 definition for the macro named @var{macro}. This command only affects
6924 definitions provided with the @command{macro define} command, described
6925 above; it cannot remove definitions present in the program being
6930 @i{(This command is not yet implemented.)} List all the macros
6931 defined using the @code{macro define} command.
6934 @cindex macros, example of debugging with
6935 Here is a transcript showing the above commands in action. First, we
6936 show our source files:
6944 #define ADD(x) (M + x)
6949 printf ("Hello, world!\n");
6951 printf ("We're so creative.\n");
6953 printf ("Goodbye, world!\n");
6960 Now, we compile the program using the @sc{gnu} C compiler, @value{NGCC}.
6961 We pass the @option{-gdwarf-2} and @option{-g3} flags to ensure the
6962 compiler includes information about preprocessor macros in the debugging
6966 $ gcc -gdwarf-2 -g3 sample.c -o sample
6970 Now, we start @value{GDBN} on our sample program:
6974 GNU gdb 2002-05-06-cvs
6975 Copyright 2002 Free Software Foundation, Inc.
6976 GDB is free software, @dots{}
6980 We can expand macros and examine their definitions, even when the
6981 program is not running. @value{GDBN} uses the current listing position
6982 to decide which macro definitions are in scope:
6985 (@value{GDBP}) list main
6988 5 #define ADD(x) (M + x)
6993 10 printf ("Hello, world!\n");
6995 12 printf ("We're so creative.\n");
6996 (@value{GDBP}) info macro ADD
6997 Defined at /home/jimb/gdb/macros/play/sample.c:5
6998 #define ADD(x) (M + x)
6999 (@value{GDBP}) info macro Q
7000 Defined at /home/jimb/gdb/macros/play/sample.h:1
7001 included at /home/jimb/gdb/macros/play/sample.c:2
7003 (@value{GDBP}) macro expand ADD(1)
7004 expands to: (42 + 1)
7005 (@value{GDBP}) macro expand-once ADD(1)
7006 expands to: once (M + 1)
7010 In the example above, note that @command{macro expand-once} expands only
7011 the macro invocation explicit in the original text --- the invocation of
7012 @code{ADD} --- but does not expand the invocation of the macro @code{M},
7013 which was introduced by @code{ADD}.
7015 Once the program is running, GDB uses the macro definitions in force at
7016 the source line of the current stack frame:
7019 (@value{GDBP}) break main
7020 Breakpoint 1 at 0x8048370: file sample.c, line 10.
7022 Starting program: /home/jimb/gdb/macros/play/sample
7024 Breakpoint 1, main () at sample.c:10
7025 10 printf ("Hello, world!\n");
7029 At line 10, the definition of the macro @code{N} at line 9 is in force:
7032 (@value{GDBP}) info macro N
7033 Defined at /home/jimb/gdb/macros/play/sample.c:9
7035 (@value{GDBP}) macro expand N Q M
7037 (@value{GDBP}) print N Q M
7042 As we step over directives that remove @code{N}'s definition, and then
7043 give it a new definition, @value{GDBN} finds the definition (or lack
7044 thereof) in force at each point:
7049 12 printf ("We're so creative.\n");
7050 (@value{GDBP}) info macro N
7051 The symbol `N' has no definition as a C/C++ preprocessor macro
7052 at /home/jimb/gdb/macros/play/sample.c:12
7055 14 printf ("Goodbye, world!\n");
7056 (@value{GDBP}) info macro N
7057 Defined at /home/jimb/gdb/macros/play/sample.c:13
7059 (@value{GDBP}) macro expand N Q M
7060 expands to: 1729 < 42
7061 (@value{GDBP}) print N Q M
7068 @chapter Tracepoints
7069 @c This chapter is based on the documentation written by Michael
7070 @c Snyder, David Taylor, Jim Blandy, and Elena Zannoni.
7073 In some applications, it is not feasible for the debugger to interrupt
7074 the program's execution long enough for the developer to learn
7075 anything helpful about its behavior. If the program's correctness
7076 depends on its real-time behavior, delays introduced by a debugger
7077 might cause the program to change its behavior drastically, or perhaps
7078 fail, even when the code itself is correct. It is useful to be able
7079 to observe the program's behavior without interrupting it.
7081 Using @value{GDBN}'s @code{trace} and @code{collect} commands, you can
7082 specify locations in the program, called @dfn{tracepoints}, and
7083 arbitrary expressions to evaluate when those tracepoints are reached.
7084 Later, using the @code{tfind} command, you can examine the values
7085 those expressions had when the program hit the tracepoints. The
7086 expressions may also denote objects in memory---structures or arrays,
7087 for example---whose values @value{GDBN} should record; while visiting
7088 a particular tracepoint, you may inspect those objects as if they were
7089 in memory at that moment. However, because @value{GDBN} records these
7090 values without interacting with you, it can do so quickly and
7091 unobtrusively, hopefully not disturbing the program's behavior.
7093 The tracepoint facility is currently available only for remote
7094 targets. @xref{Targets}. In addition, your remote target must know how
7095 to collect trace data. This functionality is implemented in the remote
7096 stub; however, none of the stubs distributed with @value{GDBN} support
7097 tracepoints as of this writing.
7099 This chapter describes the tracepoint commands and features.
7103 * Analyze Collected Data::
7104 * Tracepoint Variables::
7107 @node Set Tracepoints
7108 @section Commands to Set Tracepoints
7110 Before running such a @dfn{trace experiment}, an arbitrary number of
7111 tracepoints can be set. Like a breakpoint (@pxref{Set Breaks}), a
7112 tracepoint has a number assigned to it by @value{GDBN}. Like with
7113 breakpoints, tracepoint numbers are successive integers starting from
7114 one. Many of the commands associated with tracepoints take the
7115 tracepoint number as their argument, to identify which tracepoint to
7118 For each tracepoint, you can specify, in advance, some arbitrary set
7119 of data that you want the target to collect in the trace buffer when
7120 it hits that tracepoint. The collected data can include registers,
7121 local variables, or global data. Later, you can use @value{GDBN}
7122 commands to examine the values these data had at the time the
7125 This section describes commands to set tracepoints and associated
7126 conditions and actions.
7129 * Create and Delete Tracepoints::
7130 * Enable and Disable Tracepoints::
7131 * Tracepoint Passcounts::
7132 * Tracepoint Actions::
7133 * Listing Tracepoints::
7134 * Starting and Stopping Trace Experiment::
7137 @node Create and Delete Tracepoints
7138 @subsection Create and Delete Tracepoints
7141 @cindex set tracepoint
7144 The @code{trace} command is very similar to the @code{break} command.
7145 Its argument can be a source line, a function name, or an address in
7146 the target program. @xref{Set Breaks}. The @code{trace} command
7147 defines a tracepoint, which is a point in the target program where the
7148 debugger will briefly stop, collect some data, and then allow the
7149 program to continue. Setting a tracepoint or changing its commands
7150 doesn't take effect until the next @code{tstart} command; thus, you
7151 cannot change the tracepoint attributes once a trace experiment is
7154 Here are some examples of using the @code{trace} command:
7157 (@value{GDBP}) @b{trace foo.c:121} // a source file and line number
7159 (@value{GDBP}) @b{trace +2} // 2 lines forward
7161 (@value{GDBP}) @b{trace my_function} // first source line of function
7163 (@value{GDBP}) @b{trace *my_function} // EXACT start address of function
7165 (@value{GDBP}) @b{trace *0x2117c4} // an address
7169 You can abbreviate @code{trace} as @code{tr}.
7172 @cindex last tracepoint number
7173 @cindex recent tracepoint number
7174 @cindex tracepoint number
7175 The convenience variable @code{$tpnum} records the tracepoint number
7176 of the most recently set tracepoint.
7178 @kindex delete tracepoint
7179 @cindex tracepoint deletion
7180 @item delete tracepoint @r{[}@var{num}@r{]}
7181 Permanently delete one or more tracepoints. With no argument, the
7182 default is to delete all tracepoints.
7187 (@value{GDBP}) @b{delete trace 1 2 3} // remove three tracepoints
7189 (@value{GDBP}) @b{delete trace} // remove all tracepoints
7193 You can abbreviate this command as @code{del tr}.
7196 @node Enable and Disable Tracepoints
7197 @subsection Enable and Disable Tracepoints
7200 @kindex disable tracepoint
7201 @item disable tracepoint @r{[}@var{num}@r{]}
7202 Disable tracepoint @var{num}, or all tracepoints if no argument
7203 @var{num} is given. A disabled tracepoint will have no effect during
7204 the next trace experiment, but it is not forgotten. You can re-enable
7205 a disabled tracepoint using the @code{enable tracepoint} command.
7207 @kindex enable tracepoint
7208 @item enable tracepoint @r{[}@var{num}@r{]}
7209 Enable tracepoint @var{num}, or all tracepoints. The enabled
7210 tracepoints will become effective the next time a trace experiment is
7214 @node Tracepoint Passcounts
7215 @subsection Tracepoint Passcounts
7219 @cindex tracepoint pass count
7220 @item passcount @r{[}@var{n} @r{[}@var{num}@r{]]}
7221 Set the @dfn{passcount} of a tracepoint. The passcount is a way to
7222 automatically stop a trace experiment. If a tracepoint's passcount is
7223 @var{n}, then the trace experiment will be automatically stopped on
7224 the @var{n}'th time that tracepoint is hit. If the tracepoint number
7225 @var{num} is not specified, the @code{passcount} command sets the
7226 passcount of the most recently defined tracepoint. If no passcount is
7227 given, the trace experiment will run until stopped explicitly by the
7233 (@value{GDBP}) @b{passcount 5 2} // Stop on the 5th execution of
7234 @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// tracepoint 2}
7236 (@value{GDBP}) @b{passcount 12} // Stop on the 12th execution of the
7237 @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// most recently defined tracepoint.}
7238 (@value{GDBP}) @b{trace foo}
7239 (@value{GDBP}) @b{pass 3}
7240 (@value{GDBP}) @b{trace bar}
7241 (@value{GDBP}) @b{pass 2}
7242 (@value{GDBP}) @b{trace baz}
7243 (@value{GDBP}) @b{pass 1} // Stop tracing when foo has been
7244 @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// executed 3 times OR when bar has}
7245 @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// been executed 2 times}
7246 @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// OR when baz has been executed 1 time.}
7250 @node Tracepoint Actions
7251 @subsection Tracepoint Action Lists
7255 @cindex tracepoint actions
7256 @item actions @r{[}@var{num}@r{]}
7257 This command will prompt for a list of actions to be taken when the
7258 tracepoint is hit. If the tracepoint number @var{num} is not
7259 specified, this command sets the actions for the one that was most
7260 recently defined (so that you can define a tracepoint and then say
7261 @code{actions} without bothering about its number). You specify the
7262 actions themselves on the following lines, one action at a time, and
7263 terminate the actions list with a line containing just @code{end}. So
7264 far, the only defined actions are @code{collect} and
7265 @code{while-stepping}.
7267 @cindex remove actions from a tracepoint
7268 To remove all actions from a tracepoint, type @samp{actions @var{num}}
7269 and follow it immediately with @samp{end}.
7272 (@value{GDBP}) @b{collect @var{data}} // collect some data
7274 (@value{GDBP}) @b{while-stepping 5} // single-step 5 times, collect data
7276 (@value{GDBP}) @b{end} // signals the end of actions.
7279 In the following example, the action list begins with @code{collect}
7280 commands indicating the things to be collected when the tracepoint is
7281 hit. Then, in order to single-step and collect additional data
7282 following the tracepoint, a @code{while-stepping} command is used,
7283 followed by the list of things to be collected while stepping. The
7284 @code{while-stepping} command is terminated by its own separate
7285 @code{end} command. Lastly, the action list is terminated by an
7289 (@value{GDBP}) @b{trace foo}
7290 (@value{GDBP}) @b{actions}
7291 Enter actions for tracepoint 1, one per line:
7300 @kindex collect @r{(tracepoints)}
7301 @item collect @var{expr1}, @var{expr2}, @dots{}
7302 Collect values of the given expressions when the tracepoint is hit.
7303 This command accepts a comma-separated list of any valid expressions.
7304 In addition to global, static, or local variables, the following
7305 special arguments are supported:
7309 collect all registers
7312 collect all function arguments
7315 collect all local variables.
7318 You can give several consecutive @code{collect} commands, each one
7319 with a single argument, or one @code{collect} command with several
7320 arguments separated by commas: the effect is the same.
7322 The command @code{info scope} (@pxref{Symbols, info scope}) is
7323 particularly useful for figuring out what data to collect.
7325 @kindex while-stepping @r{(tracepoints)}
7326 @item while-stepping @var{n}
7327 Perform @var{n} single-step traces after the tracepoint, collecting
7328 new data at each step. The @code{while-stepping} command is
7329 followed by the list of what to collect while stepping (followed by
7330 its own @code{end} command):
7334 > collect $regs, myglobal
7340 You may abbreviate @code{while-stepping} as @code{ws} or
7344 @node Listing Tracepoints
7345 @subsection Listing Tracepoints
7348 @kindex info tracepoints
7350 @cindex information about tracepoints
7351 @item info tracepoints @r{[}@var{num}@r{]}
7352 Display information about the tracepoint @var{num}. If you don't specify
7353 a tracepoint number, displays information about all the tracepoints
7354 defined so far. For each tracepoint, the following information is
7361 whether it is enabled or disabled
7365 its passcount as given by the @code{passcount @var{n}} command
7367 its step count as given by the @code{while-stepping @var{n}} command
7369 where in the source files is the tracepoint set
7371 its action list as given by the @code{actions} command
7375 (@value{GDBP}) @b{info trace}
7376 Num Enb Address PassC StepC What
7377 1 y 0x002117c4 0 0 <gdb_asm>
7378 2 y 0x0020dc64 0 0 in g_test at g_test.c:1375
7379 3 y 0x0020b1f4 0 0 in get_data at ../foo.c:41
7384 This command can be abbreviated @code{info tp}.
7387 @node Starting and Stopping Trace Experiment
7388 @subsection Starting and Stopping Trace Experiment
7392 @cindex start a new trace experiment
7393 @cindex collected data discarded
7395 This command takes no arguments. It starts the trace experiment, and
7396 begins collecting data. This has the side effect of discarding all
7397 the data collected in the trace buffer during the previous trace
7401 @cindex stop a running trace experiment
7403 This command takes no arguments. It ends the trace experiment, and
7404 stops collecting data.
7406 @strong{Note}: a trace experiment and data collection may stop
7407 automatically if any tracepoint's passcount is reached
7408 (@pxref{Tracepoint Passcounts}), or if the trace buffer becomes full.
7411 @cindex status of trace data collection
7412 @cindex trace experiment, status of
7414 This command displays the status of the current trace data
7418 Here is an example of the commands we described so far:
7421 (@value{GDBP}) @b{trace gdb_c_test}
7422 (@value{GDBP}) @b{actions}
7423 Enter actions for tracepoint #1, one per line.
7424 > collect $regs,$locals,$args
7429 (@value{GDBP}) @b{tstart}
7430 [time passes @dots{}]
7431 (@value{GDBP}) @b{tstop}
7435 @node Analyze Collected Data
7436 @section Using the collected data
7438 After the tracepoint experiment ends, you use @value{GDBN} commands
7439 for examining the trace data. The basic idea is that each tracepoint
7440 collects a trace @dfn{snapshot} every time it is hit and another
7441 snapshot every time it single-steps. All these snapshots are
7442 consecutively numbered from zero and go into a buffer, and you can
7443 examine them later. The way you examine them is to @dfn{focus} on a
7444 specific trace snapshot. When the remote stub is focused on a trace
7445 snapshot, it will respond to all @value{GDBN} requests for memory and
7446 registers by reading from the buffer which belongs to that snapshot,
7447 rather than from @emph{real} memory or registers of the program being
7448 debugged. This means that @strong{all} @value{GDBN} commands
7449 (@code{print}, @code{info registers}, @code{backtrace}, etc.) will
7450 behave as if we were currently debugging the program state as it was
7451 when the tracepoint occurred. Any requests for data that are not in
7452 the buffer will fail.
7455 * tfind:: How to select a trace snapshot
7456 * tdump:: How to display all data for a snapshot
7457 * save-tracepoints:: How to save tracepoints for a future run
7461 @subsection @code{tfind @var{n}}
7464 @cindex select trace snapshot
7465 @cindex find trace snapshot
7466 The basic command for selecting a trace snapshot from the buffer is
7467 @code{tfind @var{n}}, which finds trace snapshot number @var{n},
7468 counting from zero. If no argument @var{n} is given, the next
7469 snapshot is selected.
7471 Here are the various forms of using the @code{tfind} command.
7475 Find the first snapshot in the buffer. This is a synonym for
7476 @code{tfind 0} (since 0 is the number of the first snapshot).
7479 Stop debugging trace snapshots, resume @emph{live} debugging.
7482 Same as @samp{tfind none}.
7485 No argument means find the next trace snapshot.
7488 Find the previous trace snapshot before the current one. This permits
7489 retracing earlier steps.
7491 @item tfind tracepoint @var{num}
7492 Find the next snapshot associated with tracepoint @var{num}. Search
7493 proceeds forward from the last examined trace snapshot. If no
7494 argument @var{num} is given, it means find the next snapshot collected
7495 for the same tracepoint as the current snapshot.
7497 @item tfind pc @var{addr}
7498 Find the next snapshot associated with the value @var{addr} of the
7499 program counter. Search proceeds forward from the last examined trace
7500 snapshot. If no argument @var{addr} is given, it means find the next
7501 snapshot with the same value of PC as the current snapshot.
7503 @item tfind outside @var{addr1}, @var{addr2}
7504 Find the next snapshot whose PC is outside the given range of
7507 @item tfind range @var{addr1}, @var{addr2}
7508 Find the next snapshot whose PC is between @var{addr1} and
7509 @var{addr2}. @c FIXME: Is the range inclusive or exclusive?
7511 @item tfind line @r{[}@var{file}:@r{]}@var{n}
7512 Find the next snapshot associated with the source line @var{n}. If
7513 the optional argument @var{file} is given, refer to line @var{n} in
7514 that source file. Search proceeds forward from the last examined
7515 trace snapshot. If no argument @var{n} is given, it means find the
7516 next line other than the one currently being examined; thus saying
7517 @code{tfind line} repeatedly can appear to have the same effect as
7518 stepping from line to line in a @emph{live} debugging session.
7521 The default arguments for the @code{tfind} commands are specifically
7522 designed to make it easy to scan through the trace buffer. For
7523 instance, @code{tfind} with no argument selects the next trace
7524 snapshot, and @code{tfind -} with no argument selects the previous
7525 trace snapshot. So, by giving one @code{tfind} command, and then
7526 simply hitting @key{RET} repeatedly you can examine all the trace
7527 snapshots in order. Or, by saying @code{tfind -} and then hitting
7528 @key{RET} repeatedly you can examine the snapshots in reverse order.
7529 The @code{tfind line} command with no argument selects the snapshot
7530 for the next source line executed. The @code{tfind pc} command with
7531 no argument selects the next snapshot with the same program counter
7532 (PC) as the current frame. The @code{tfind tracepoint} command with
7533 no argument selects the next trace snapshot collected by the same
7534 tracepoint as the current one.
7536 In addition to letting you scan through the trace buffer manually,
7537 these commands make it easy to construct @value{GDBN} scripts that
7538 scan through the trace buffer and print out whatever collected data
7539 you are interested in. Thus, if we want to examine the PC, FP, and SP
7540 registers from each trace frame in the buffer, we can say this:
7543 (@value{GDBP}) @b{tfind start}
7544 (@value{GDBP}) @b{while ($trace_frame != -1)}
7545 > printf "Frame %d, PC = %08X, SP = %08X, FP = %08X\n", \
7546 $trace_frame, $pc, $sp, $fp
7550 Frame 0, PC = 0020DC64, SP = 0030BF3C, FP = 0030BF44
7551 Frame 1, PC = 0020DC6C, SP = 0030BF38, FP = 0030BF44
7552 Frame 2, PC = 0020DC70, SP = 0030BF34, FP = 0030BF44
7553 Frame 3, PC = 0020DC74, SP = 0030BF30, FP = 0030BF44
7554 Frame 4, PC = 0020DC78, SP = 0030BF2C, FP = 0030BF44
7555 Frame 5, PC = 0020DC7C, SP = 0030BF28, FP = 0030BF44
7556 Frame 6, PC = 0020DC80, SP = 0030BF24, FP = 0030BF44
7557 Frame 7, PC = 0020DC84, SP = 0030BF20, FP = 0030BF44
7558 Frame 8, PC = 0020DC88, SP = 0030BF1C, FP = 0030BF44
7559 Frame 9, PC = 0020DC8E, SP = 0030BF18, FP = 0030BF44
7560 Frame 10, PC = 00203F6C, SP = 0030BE3C, FP = 0030BF14
7563 Or, if we want to examine the variable @code{X} at each source line in
7567 (@value{GDBP}) @b{tfind start}
7568 (@value{GDBP}) @b{while ($trace_frame != -1)}
7569 > printf "Frame %d, X == %d\n", $trace_frame, X
7579 @subsection @code{tdump}
7581 @cindex dump all data collected at tracepoint
7582 @cindex tracepoint data, display
7584 This command takes no arguments. It prints all the data collected at
7585 the current trace snapshot.
7588 (@value{GDBP}) @b{trace 444}
7589 (@value{GDBP}) @b{actions}
7590 Enter actions for tracepoint #2, one per line:
7591 > collect $regs, $locals, $args, gdb_long_test
7594 (@value{GDBP}) @b{tstart}
7596 (@value{GDBP}) @b{tfind line 444}
7597 #0 gdb_test (p1=0x11, p2=0x22, p3=0x33, p4=0x44, p5=0x55, p6=0x66)
7599 444 printp( "%s: arguments = 0x%X 0x%X 0x%X 0x%X 0x%X 0x%X\n", )
7601 (@value{GDBP}) @b{tdump}
7602 Data collected at tracepoint 2, trace frame 1:
7603 d0 0xc4aa0085 -995491707
7607 d4 0x71aea3d 119204413
7612 a1 0x3000668 50333288
7615 a4 0x3000698 50333336
7617 fp 0x30bf3c 0x30bf3c
7618 sp 0x30bf34 0x30bf34
7620 pc 0x20b2c8 0x20b2c8
7624 p = 0x20e5b4 "gdb-test"
7631 gdb_long_test = 17 '\021'
7636 @node save-tracepoints
7637 @subsection @code{save-tracepoints @var{filename}}
7638 @kindex save-tracepoints
7639 @cindex save tracepoints for future sessions
7641 This command saves all current tracepoint definitions together with
7642 their actions and passcounts, into a file @file{@var{filename}}
7643 suitable for use in a later debugging session. To read the saved
7644 tracepoint definitions, use the @code{source} command (@pxref{Command
7647 @node Tracepoint Variables
7648 @section Convenience Variables for Tracepoints
7649 @cindex tracepoint variables
7650 @cindex convenience variables for tracepoints
7653 @vindex $trace_frame
7654 @item (int) $trace_frame
7655 The current trace snapshot (a.k.a.@: @dfn{frame}) number, or -1 if no
7656 snapshot is selected.
7659 @item (int) $tracepoint
7660 The tracepoint for the current trace snapshot.
7663 @item (int) $trace_line
7664 The line number for the current trace snapshot.
7667 @item (char []) $trace_file
7668 The source file for the current trace snapshot.
7671 @item (char []) $trace_func
7672 The name of the function containing @code{$tracepoint}.
7675 Note: @code{$trace_file} is not suitable for use in @code{printf},
7676 use @code{output} instead.
7678 Here's a simple example of using these convenience variables for
7679 stepping through all the trace snapshots and printing some of their
7683 (@value{GDBP}) @b{tfind start}
7685 (@value{GDBP}) @b{while $trace_frame != -1}
7686 > output $trace_file
7687 > printf ", line %d (tracepoint #%d)\n", $trace_line, $tracepoint
7693 @chapter Debugging Programs That Use Overlays
7696 If your program is too large to fit completely in your target system's
7697 memory, you can sometimes use @dfn{overlays} to work around this
7698 problem. @value{GDBN} provides some support for debugging programs that
7702 * How Overlays Work:: A general explanation of overlays.
7703 * Overlay Commands:: Managing overlays in @value{GDBN}.
7704 * Automatic Overlay Debugging:: @value{GDBN} can find out which overlays are
7705 mapped by asking the inferior.
7706 * Overlay Sample Program:: A sample program using overlays.
7709 @node How Overlays Work
7710 @section How Overlays Work
7711 @cindex mapped overlays
7712 @cindex unmapped overlays
7713 @cindex load address, overlay's
7714 @cindex mapped address
7715 @cindex overlay area
7717 Suppose you have a computer whose instruction address space is only 64
7718 kilobytes long, but which has much more memory which can be accessed by
7719 other means: special instructions, segment registers, or memory
7720 management hardware, for example. Suppose further that you want to
7721 adapt a program which is larger than 64 kilobytes to run on this system.
7723 One solution is to identify modules of your program which are relatively
7724 independent, and need not call each other directly; call these modules
7725 @dfn{overlays}. Separate the overlays from the main program, and place
7726 their machine code in the larger memory. Place your main program in
7727 instruction memory, but leave at least enough space there to hold the
7728 largest overlay as well.
7730 Now, to call a function located in an overlay, you must first copy that
7731 overlay's machine code from the large memory into the space set aside
7732 for it in the instruction memory, and then jump to its entry point
7735 @c NB: In the below the mapped area's size is greater or equal to the
7736 @c size of all overlays. This is intentional to remind the developer
7737 @c that overlays don't necessarily need to be the same size.
7741 Data Instruction Larger
7742 Address Space Address Space Address Space
7743 +-----------+ +-----------+ +-----------+
7745 +-----------+ +-----------+ +-----------+<-- overlay 1
7746 | program | | main | .----| overlay 1 | load address
7747 | variables | | program | | +-----------+
7748 | and heap | | | | | |
7749 +-----------+ | | | +-----------+<-- overlay 2
7750 | | +-----------+ | | | load address
7751 +-----------+ | | | .-| overlay 2 |
7753 mapped --->+-----------+ | | +-----------+
7755 | overlay | <-' | | |
7756 | area | <---' +-----------+<-- overlay 3
7757 | | <---. | | load address
7758 +-----------+ `--| overlay 3 |
7765 @anchor{A code overlay}A code overlay
7769 The diagram (@pxref{A code overlay}) shows a system with separate data
7770 and instruction address spaces. To map an overlay, the program copies
7771 its code from the larger address space to the instruction address space.
7772 Since the overlays shown here all use the same mapped address, only one
7773 may be mapped at a time. For a system with a single address space for
7774 data and instructions, the diagram would be similar, except that the
7775 program variables and heap would share an address space with the main
7776 program and the overlay area.
7778 An overlay loaded into instruction memory and ready for use is called a
7779 @dfn{mapped} overlay; its @dfn{mapped address} is its address in the
7780 instruction memory. An overlay not present (or only partially present)
7781 in instruction memory is called @dfn{unmapped}; its @dfn{load address}
7782 is its address in the larger memory. The mapped address is also called
7783 the @dfn{virtual memory address}, or @dfn{VMA}; the load address is also
7784 called the @dfn{load memory address}, or @dfn{LMA}.
7786 Unfortunately, overlays are not a completely transparent way to adapt a
7787 program to limited instruction memory. They introduce a new set of
7788 global constraints you must keep in mind as you design your program:
7793 Before calling or returning to a function in an overlay, your program
7794 must make sure that overlay is actually mapped. Otherwise, the call or
7795 return will transfer control to the right address, but in the wrong
7796 overlay, and your program will probably crash.
7799 If the process of mapping an overlay is expensive on your system, you
7800 will need to choose your overlays carefully to minimize their effect on
7801 your program's performance.
7804 The executable file you load onto your system must contain each
7805 overlay's instructions, appearing at the overlay's load address, not its
7806 mapped address. However, each overlay's instructions must be relocated
7807 and its symbols defined as if the overlay were at its mapped address.
7808 You can use GNU linker scripts to specify different load and relocation
7809 addresses for pieces of your program; see @ref{Overlay Description,,,
7810 ld.info, Using ld: the GNU linker}.
7813 The procedure for loading executable files onto your system must be able
7814 to load their contents into the larger address space as well as the
7815 instruction and data spaces.
7819 The overlay system described above is rather simple, and could be
7820 improved in many ways:
7825 If your system has suitable bank switch registers or memory management
7826 hardware, you could use those facilities to make an overlay's load area
7827 contents simply appear at their mapped address in instruction space.
7828 This would probably be faster than copying the overlay to its mapped
7829 area in the usual way.
7832 If your overlays are small enough, you could set aside more than one
7833 overlay area, and have more than one overlay mapped at a time.
7836 You can use overlays to manage data, as well as instructions. In
7837 general, data overlays are even less transparent to your design than
7838 code overlays: whereas code overlays only require care when you call or
7839 return to functions, data overlays require care every time you access
7840 the data. Also, if you change the contents of a data overlay, you
7841 must copy its contents back out to its load address before you can copy a
7842 different data overlay into the same mapped area.
7847 @node Overlay Commands
7848 @section Overlay Commands
7850 To use @value{GDBN}'s overlay support, each overlay in your program must
7851 correspond to a separate section of the executable file. The section's
7852 virtual memory address and load memory address must be the overlay's
7853 mapped and load addresses. Identifying overlays with sections allows
7854 @value{GDBN} to determine the appropriate address of a function or
7855 variable, depending on whether the overlay is mapped or not.
7857 @value{GDBN}'s overlay commands all start with the word @code{overlay};
7858 you can abbreviate this as @code{ov} or @code{ovly}. The commands are:
7863 Disable @value{GDBN}'s overlay support. When overlay support is
7864 disabled, @value{GDBN} assumes that all functions and variables are
7865 always present at their mapped addresses. By default, @value{GDBN}'s
7866 overlay support is disabled.
7868 @item overlay manual
7869 @cindex manual overlay debugging
7870 Enable @dfn{manual} overlay debugging. In this mode, @value{GDBN}
7871 relies on you to tell it which overlays are mapped, and which are not,
7872 using the @code{overlay map-overlay} and @code{overlay unmap-overlay}
7873 commands described below.
7875 @item overlay map-overlay @var{overlay}
7876 @itemx overlay map @var{overlay}
7877 @cindex map an overlay
7878 Tell @value{GDBN} that @var{overlay} is now mapped; @var{overlay} must
7879 be the name of the object file section containing the overlay. When an
7880 overlay is mapped, @value{GDBN} assumes it can find the overlay's
7881 functions and variables at their mapped addresses. @value{GDBN} assumes
7882 that any other overlays whose mapped ranges overlap that of
7883 @var{overlay} are now unmapped.
7885 @item overlay unmap-overlay @var{overlay}
7886 @itemx overlay unmap @var{overlay}
7887 @cindex unmap an overlay
7888 Tell @value{GDBN} that @var{overlay} is no longer mapped; @var{overlay}
7889 must be the name of the object file section containing the overlay.
7890 When an overlay is unmapped, @value{GDBN} assumes it can find the
7891 overlay's functions and variables at their load addresses.
7894 Enable @dfn{automatic} overlay debugging. In this mode, @value{GDBN}
7895 consults a data structure the overlay manager maintains in the inferior
7896 to see which overlays are mapped. For details, see @ref{Automatic
7899 @item overlay load-target
7901 @cindex reloading the overlay table
7902 Re-read the overlay table from the inferior. Normally, @value{GDBN}
7903 re-reads the table @value{GDBN} automatically each time the inferior
7904 stops, so this command should only be necessary if you have changed the
7905 overlay mapping yourself using @value{GDBN}. This command is only
7906 useful when using automatic overlay debugging.
7908 @item overlay list-overlays
7910 @cindex listing mapped overlays
7911 Display a list of the overlays currently mapped, along with their mapped
7912 addresses, load addresses, and sizes.
7916 Normally, when @value{GDBN} prints a code address, it includes the name
7917 of the function the address falls in:
7920 (@value{GDBP}) print main
7921 $3 = @{int ()@} 0x11a0 <main>
7924 When overlay debugging is enabled, @value{GDBN} recognizes code in
7925 unmapped overlays, and prints the names of unmapped functions with
7926 asterisks around them. For example, if @code{foo} is a function in an
7927 unmapped overlay, @value{GDBN} prints it this way:
7930 (@value{GDBP}) overlay list
7931 No sections are mapped.
7932 (@value{GDBP}) print foo
7933 $5 = @{int (int)@} 0x100000 <*foo*>
7936 When @code{foo}'s overlay is mapped, @value{GDBN} prints the function's
7940 (@value{GDBP}) overlay list
7941 Section .ov.foo.text, loaded at 0x100000 - 0x100034,
7942 mapped at 0x1016 - 0x104a
7943 (@value{GDBP}) print foo
7944 $6 = @{int (int)@} 0x1016 <foo>
7947 When overlay debugging is enabled, @value{GDBN} can find the correct
7948 address for functions and variables in an overlay, whether or not the
7949 overlay is mapped. This allows most @value{GDBN} commands, like
7950 @code{break} and @code{disassemble}, to work normally, even on unmapped
7951 code. However, @value{GDBN}'s breakpoint support has some limitations:
7955 @cindex breakpoints in overlays
7956 @cindex overlays, setting breakpoints in
7957 You can set breakpoints in functions in unmapped overlays, as long as
7958 @value{GDBN} can write to the overlay at its load address.
7960 @value{GDBN} can not set hardware or simulator-based breakpoints in
7961 unmapped overlays. However, if you set a breakpoint at the end of your
7962 overlay manager (and tell @value{GDBN} which overlays are now mapped, if
7963 you are using manual overlay management), @value{GDBN} will re-set its
7964 breakpoints properly.
7968 @node Automatic Overlay Debugging
7969 @section Automatic Overlay Debugging
7970 @cindex automatic overlay debugging
7972 @value{GDBN} can automatically track which overlays are mapped and which
7973 are not, given some simple co-operation from the overlay manager in the
7974 inferior. If you enable automatic overlay debugging with the
7975 @code{overlay auto} command (@pxref{Overlay Commands}), @value{GDBN}
7976 looks in the inferior's memory for certain variables describing the
7977 current state of the overlays.
7979 Here are the variables your overlay manager must define to support
7980 @value{GDBN}'s automatic overlay debugging:
7984 @item @code{_ovly_table}:
7985 This variable must be an array of the following structures:
7990 /* The overlay's mapped address. */
7993 /* The size of the overlay, in bytes. */
7996 /* The overlay's load address. */
7999 /* Non-zero if the overlay is currently mapped;
8001 unsigned long mapped;
8005 @item @code{_novlys}:
8006 This variable must be a four-byte signed integer, holding the total
8007 number of elements in @code{_ovly_table}.
8011 To decide whether a particular overlay is mapped or not, @value{GDBN}
8012 looks for an entry in @w{@code{_ovly_table}} whose @code{vma} and
8013 @code{lma} members equal the VMA and LMA of the overlay's section in the
8014 executable file. When @value{GDBN} finds a matching entry, it consults
8015 the entry's @code{mapped} member to determine whether the overlay is
8018 In addition, your overlay manager may define a function called
8019 @code{_ovly_debug_event}. If this function is defined, @value{GDBN}
8020 will silently set a breakpoint there. If the overlay manager then
8021 calls this function whenever it has changed the overlay table, this
8022 will enable @value{GDBN} to accurately keep track of which overlays
8023 are in program memory, and update any breakpoints that may be set
8024 in overlays. This will allow breakpoints to work even if the
8025 overlays are kept in ROM or other non-writable memory while they
8026 are not being executed.
8028 @node Overlay Sample Program
8029 @section Overlay Sample Program
8030 @cindex overlay example program
8032 When linking a program which uses overlays, you must place the overlays
8033 at their load addresses, while relocating them to run at their mapped
8034 addresses. To do this, you must write a linker script (@pxref{Overlay
8035 Description,,, ld.info, Using ld: the GNU linker}). Unfortunately,
8036 since linker scripts are specific to a particular host system, target
8037 architecture, and target memory layout, this manual cannot provide
8038 portable sample code demonstrating @value{GDBN}'s overlay support.
8040 However, the @value{GDBN} source distribution does contain an overlaid
8041 program, with linker scripts for a few systems, as part of its test
8042 suite. The program consists of the following files from
8043 @file{gdb/testsuite/gdb.base}:
8047 The main program file.
8049 A simple overlay manager, used by @file{overlays.c}.
8054 Overlay modules, loaded and used by @file{overlays.c}.
8057 Linker scripts for linking the test program on the @code{d10v-elf}
8058 and @code{m32r-elf} targets.
8061 You can build the test program using the @code{d10v-elf} GCC
8062 cross-compiler like this:
8065 $ d10v-elf-gcc -g -c overlays.c
8066 $ d10v-elf-gcc -g -c ovlymgr.c
8067 $ d10v-elf-gcc -g -c foo.c
8068 $ d10v-elf-gcc -g -c bar.c
8069 $ d10v-elf-gcc -g -c baz.c
8070 $ d10v-elf-gcc -g -c grbx.c
8071 $ d10v-elf-gcc -g overlays.o ovlymgr.o foo.o bar.o \
8072 baz.o grbx.o -Wl,-Td10v.ld -o overlays
8075 The build process is identical for any other architecture, except that
8076 you must substitute the appropriate compiler and linker script for the
8077 target system for @code{d10v-elf-gcc} and @code{d10v.ld}.
8081 @chapter Using @value{GDBN} with Different Languages
8084 Although programming languages generally have common aspects, they are
8085 rarely expressed in the same manner. For instance, in ANSI C,
8086 dereferencing a pointer @code{p} is accomplished by @code{*p}, but in
8087 Modula-2, it is accomplished by @code{p^}. Values can also be
8088 represented (and displayed) differently. Hex numbers in C appear as
8089 @samp{0x1ae}, while in Modula-2 they appear as @samp{1AEH}.
8091 @cindex working language
8092 Language-specific information is built into @value{GDBN} for some languages,
8093 allowing you to express operations like the above in your program's
8094 native language, and allowing @value{GDBN} to output values in a manner
8095 consistent with the syntax of your program's native language. The
8096 language you use to build expressions is called the @dfn{working
8100 * Setting:: Switching between source languages
8101 * Show:: Displaying the language
8102 * Checks:: Type and range checks
8103 * Supported languages:: Supported languages
8104 * Unsupported languages:: Unsupported languages
8108 @section Switching between source languages
8110 There are two ways to control the working language---either have @value{GDBN}
8111 set it automatically, or select it manually yourself. You can use the
8112 @code{set language} command for either purpose. On startup, @value{GDBN}
8113 defaults to setting the language automatically. The working language is
8114 used to determine how expressions you type are interpreted, how values
8117 In addition to the working language, every source file that
8118 @value{GDBN} knows about has its own working language. For some object
8119 file formats, the compiler might indicate which language a particular
8120 source file is in. However, most of the time @value{GDBN} infers the
8121 language from the name of the file. The language of a source file
8122 controls whether C@t{++} names are demangled---this way @code{backtrace} can
8123 show each frame appropriately for its own language. There is no way to
8124 set the language of a source file from within @value{GDBN}, but you can
8125 set the language associated with a filename extension. @xref{Show, ,
8126 Displaying the language}.
8128 This is most commonly a problem when you use a program, such
8129 as @code{cfront} or @code{f2c}, that generates C but is written in
8130 another language. In that case, make the
8131 program use @code{#line} directives in its C output; that way
8132 @value{GDBN} will know the correct language of the source code of the original
8133 program, and will display that source code, not the generated C code.
8136 * Filenames:: Filename extensions and languages.
8137 * Manually:: Setting the working language manually
8138 * Automatically:: Having @value{GDBN} infer the source language
8142 @subsection List of filename extensions and languages
8144 If a source file name ends in one of the following extensions, then
8145 @value{GDBN} infers that its language is the one indicated.
8166 Objective-C source file
8173 Modula-2 source file
8177 Assembler source file. This actually behaves almost like C, but
8178 @value{GDBN} does not skip over function prologues when stepping.
8181 In addition, you may set the language associated with a filename
8182 extension. @xref{Show, , Displaying the language}.
8185 @subsection Setting the working language
8187 If you allow @value{GDBN} to set the language automatically,
8188 expressions are interpreted the same way in your debugging session and
8191 @kindex set language
8192 If you wish, you may set the language manually. To do this, issue the
8193 command @samp{set language @var{lang}}, where @var{lang} is the name of
8195 @code{c} or @code{modula-2}.
8196 For a list of the supported languages, type @samp{set language}.
8198 Setting the language manually prevents @value{GDBN} from updating the working
8199 language automatically. This can lead to confusion if you try
8200 to debug a program when the working language is not the same as the
8201 source language, when an expression is acceptable to both
8202 languages---but means different things. For instance, if the current
8203 source file were written in C, and @value{GDBN} was parsing Modula-2, a
8211 might not have the effect you intended. In C, this means to add
8212 @code{b} and @code{c} and place the result in @code{a}. The result
8213 printed would be the value of @code{a}. In Modula-2, this means to compare
8214 @code{a} to the result of @code{b+c}, yielding a @code{BOOLEAN} value.
8217 @subsection Having @value{GDBN} infer the source language
8219 To have @value{GDBN} set the working language automatically, use
8220 @samp{set language local} or @samp{set language auto}. @value{GDBN}
8221 then infers the working language. That is, when your program stops in a
8222 frame (usually by encountering a breakpoint), @value{GDBN} sets the
8223 working language to the language recorded for the function in that
8224 frame. If the language for a frame is unknown (that is, if the function
8225 or block corresponding to the frame was defined in a source file that
8226 does not have a recognized extension), the current working language is
8227 not changed, and @value{GDBN} issues a warning.
8229 This may not seem necessary for most programs, which are written
8230 entirely in one source language. However, program modules and libraries
8231 written in one source language can be used by a main program written in
8232 a different source language. Using @samp{set language auto} in this
8233 case frees you from having to set the working language manually.
8236 @section Displaying the language
8238 The following commands help you find out which language is the
8239 working language, and also what language source files were written in.
8243 @kindex show language
8244 Display the current working language. This is the
8245 language you can use with commands such as @code{print} to
8246 build and compute expressions that may involve variables in your program.
8249 @kindex info frame@r{, show the source language}
8250 Display the source language for this frame. This language becomes the
8251 working language if you use an identifier from this frame.
8252 @xref{Frame Info, ,Information about a frame}, to identify the other
8253 information listed here.
8256 @kindex info source@r{, show the source language}
8257 Display the source language of this source file.
8258 @xref{Symbols, ,Examining the Symbol Table}, to identify the other
8259 information listed here.
8262 In unusual circumstances, you may have source files with extensions
8263 not in the standard list. You can then set the extension associated
8264 with a language explicitly:
8267 @item set extension-language @var{ext} @var{language}
8268 @kindex set extension-language
8269 Tell @value{GDBN} that source files with extension @var{ext} are to be
8270 assumed as written in the source language @var{language}.
8272 @item info extensions
8273 @kindex info extensions
8274 List all the filename extensions and the associated languages.
8278 @section Type and range checking
8281 @emph{Warning:} In this release, the @value{GDBN} commands for type and range
8282 checking are included, but they do not yet have any effect. This
8283 section documents the intended facilities.
8285 @c FIXME remove warning when type/range code added
8287 Some languages are designed to guard you against making seemingly common
8288 errors through a series of compile- and run-time checks. These include
8289 checking the type of arguments to functions and operators, and making
8290 sure mathematical overflows are caught at run time. Checks such as
8291 these help to ensure a program's correctness once it has been compiled
8292 by eliminating type mismatches, and providing active checks for range
8293 errors when your program is running.
8295 @value{GDBN} can check for conditions like the above if you wish.
8296 Although @value{GDBN} does not check the statements in your program,
8297 it can check expressions entered directly into @value{GDBN} for
8298 evaluation via the @code{print} command, for example. As with the
8299 working language, @value{GDBN} can also decide whether or not to check
8300 automatically based on your program's source language.
8301 @xref{Supported languages, ,Supported languages}, for the default
8302 settings of supported languages.
8305 * Type Checking:: An overview of type checking
8306 * Range Checking:: An overview of range checking
8309 @cindex type checking
8310 @cindex checks, type
8312 @subsection An overview of type checking
8314 Some languages, such as Modula-2, are strongly typed, meaning that the
8315 arguments to operators and functions have to be of the correct type,
8316 otherwise an error occurs. These checks prevent type mismatch
8317 errors from ever causing any run-time problems. For example,
8325 The second example fails because the @code{CARDINAL} 1 is not
8326 type-compatible with the @code{REAL} 2.3.
8328 For the expressions you use in @value{GDBN} commands, you can tell the
8329 @value{GDBN} type checker to skip checking;
8330 to treat any mismatches as errors and abandon the expression;
8331 or to only issue warnings when type mismatches occur,
8332 but evaluate the expression anyway. When you choose the last of
8333 these, @value{GDBN} evaluates expressions like the second example above, but
8334 also issues a warning.
8336 Even if you turn type checking off, there may be other reasons
8337 related to type that prevent @value{GDBN} from evaluating an expression.
8338 For instance, @value{GDBN} does not know how to add an @code{int} and
8339 a @code{struct foo}. These particular type errors have nothing to do
8340 with the language in use, and usually arise from expressions, such as
8341 the one described above, which make little sense to evaluate anyway.
8343 Each language defines to what degree it is strict about type. For
8344 instance, both Modula-2 and C require the arguments to arithmetical
8345 operators to be numbers. In C, enumerated types and pointers can be
8346 represented as numbers, so that they are valid arguments to mathematical
8347 operators. @xref{Supported languages, ,Supported languages}, for further
8348 details on specific languages.
8350 @value{GDBN} provides some additional commands for controlling the type checker:
8352 @kindex set check type
8353 @kindex show check type
8355 @item set check type auto
8356 Set type checking on or off based on the current working language.
8357 @xref{Supported languages, ,Supported languages}, for the default settings for
8360 @item set check type on
8361 @itemx set check type off
8362 Set type checking on or off, overriding the default setting for the
8363 current working language. Issue a warning if the setting does not
8364 match the language default. If any type mismatches occur in
8365 evaluating an expression while type checking is on, @value{GDBN} prints a
8366 message and aborts evaluation of the expression.
8368 @item set check type warn
8369 Cause the type checker to issue warnings, but to always attempt to
8370 evaluate the expression. Evaluating the expression may still
8371 be impossible for other reasons. For example, @value{GDBN} cannot add
8372 numbers and structures.
8375 Show the current setting of the type checker, and whether or not @value{GDBN}
8376 is setting it automatically.
8379 @cindex range checking
8380 @cindex checks, range
8381 @node Range Checking
8382 @subsection An overview of range checking
8384 In some languages (such as Modula-2), it is an error to exceed the
8385 bounds of a type; this is enforced with run-time checks. Such range
8386 checking is meant to ensure program correctness by making sure
8387 computations do not overflow, or indices on an array element access do
8388 not exceed the bounds of the array.
8390 For expressions you use in @value{GDBN} commands, you can tell
8391 @value{GDBN} to treat range errors in one of three ways: ignore them,
8392 always treat them as errors and abandon the expression, or issue
8393 warnings but evaluate the expression anyway.
8395 A range error can result from numerical overflow, from exceeding an
8396 array index bound, or when you type a constant that is not a member
8397 of any type. Some languages, however, do not treat overflows as an
8398 error. In many implementations of C, mathematical overflow causes the
8399 result to ``wrap around'' to lower values---for example, if @var{m} is
8400 the largest integer value, and @var{s} is the smallest, then
8403 @var{m} + 1 @result{} @var{s}
8406 This, too, is specific to individual languages, and in some cases
8407 specific to individual compilers or machines. @xref{Supported languages, ,
8408 Supported languages}, for further details on specific languages.
8410 @value{GDBN} provides some additional commands for controlling the range checker:
8412 @kindex set check range
8413 @kindex show check range
8415 @item set check range auto
8416 Set range checking on or off based on the current working language.
8417 @xref{Supported languages, ,Supported languages}, for the default settings for
8420 @item set check range on
8421 @itemx set check range off
8422 Set range checking on or off, overriding the default setting for the
8423 current working language. A warning is issued if the setting does not
8424 match the language default. If a range error occurs and range checking is on,
8425 then a message is printed and evaluation of the expression is aborted.
8427 @item set check range warn
8428 Output messages when the @value{GDBN} range checker detects a range error,
8429 but attempt to evaluate the expression anyway. Evaluating the
8430 expression may still be impossible for other reasons, such as accessing
8431 memory that the process does not own (a typical example from many Unix
8435 Show the current setting of the range checker, and whether or not it is
8436 being set automatically by @value{GDBN}.
8439 @node Supported languages
8440 @section Supported languages
8442 @value{GDBN} supports C, C@t{++}, Objective-C, Fortran, Java, Pascal,
8443 assembly, Modula-2, and Ada.
8444 @c This is false ...
8445 Some @value{GDBN} features may be used in expressions regardless of the
8446 language you use: the @value{GDBN} @code{@@} and @code{::} operators,
8447 and the @samp{@{type@}addr} construct (@pxref{Expressions,
8448 ,Expressions}) can be used with the constructs of any supported
8451 The following sections detail to what degree each source language is
8452 supported by @value{GDBN}. These sections are not meant to be language
8453 tutorials or references, but serve only as a reference guide to what the
8454 @value{GDBN} expression parser accepts, and what input and output
8455 formats should look like for different languages. There are many good
8456 books written on each of these languages; please look to these for a
8457 language reference or tutorial.
8461 * Objective-C:: Objective-C
8464 * Modula-2:: Modula-2
8469 @subsection C and C@t{++}
8471 @cindex C and C@t{++}
8472 @cindex expressions in C or C@t{++}
8474 Since C and C@t{++} are so closely related, many features of @value{GDBN} apply
8475 to both languages. Whenever this is the case, we discuss those languages
8479 @cindex @code{g++}, @sc{gnu} C@t{++} compiler
8480 @cindex @sc{gnu} C@t{++}
8481 The C@t{++} debugging facilities are jointly implemented by the C@t{++}
8482 compiler and @value{GDBN}. Therefore, to debug your C@t{++} code
8483 effectively, you must compile your C@t{++} programs with a supported
8484 C@t{++} compiler, such as @sc{gnu} @code{g++}, or the HP ANSI C@t{++}
8485 compiler (@code{aCC}).
8487 For best results when using @sc{gnu} C@t{++}, use the DWARF 2 debugging
8488 format; if it doesn't work on your system, try the stabs+ debugging
8489 format. You can select those formats explicitly with the @code{g++}
8490 command-line options @option{-gdwarf-2} and @option{-gstabs+}.
8491 @xref{Debugging Options,,Options for Debugging Your Program or @sc{gnu}
8492 CC, gcc.info, Using @sc{gnu} CC}.
8495 * C Operators:: C and C@t{++} operators
8496 * C Constants:: C and C@t{++} constants
8497 * C plus plus expressions:: C@t{++} expressions
8498 * C Defaults:: Default settings for C and C@t{++}
8499 * C Checks:: C and C@t{++} type and range checks
8500 * Debugging C:: @value{GDBN} and C
8501 * Debugging C plus plus:: @value{GDBN} features for C@t{++}
8505 @subsubsection C and C@t{++} operators
8507 @cindex C and C@t{++} operators
8509 Operators must be defined on values of specific types. For instance,
8510 @code{+} is defined on numbers, but not on structures. Operators are
8511 often defined on groups of types.
8513 For the purposes of C and C@t{++}, the following definitions hold:
8518 @emph{Integral types} include @code{int} with any of its storage-class
8519 specifiers; @code{char}; @code{enum}; and, for C@t{++}, @code{bool}.
8522 @emph{Floating-point types} include @code{float}, @code{double}, and
8523 @code{long double} (if supported by the target platform).
8526 @emph{Pointer types} include all types defined as @code{(@var{type} *)}.
8529 @emph{Scalar types} include all of the above.
8534 The following operators are supported. They are listed here
8535 in order of increasing precedence:
8539 The comma or sequencing operator. Expressions in a comma-separated list
8540 are evaluated from left to right, with the result of the entire
8541 expression being the last expression evaluated.
8544 Assignment. The value of an assignment expression is the value
8545 assigned. Defined on scalar types.
8548 Used in an expression of the form @w{@code{@var{a} @var{op}= @var{b}}},
8549 and translated to @w{@code{@var{a} = @var{a op b}}}.
8550 @w{@code{@var{op}=}} and @code{=} have the same precedence.
8551 @var{op} is any one of the operators @code{|}, @code{^}, @code{&},
8552 @code{<<}, @code{>>}, @code{+}, @code{-}, @code{*}, @code{/}, @code{%}.
8555 The ternary operator. @code{@var{a} ? @var{b} : @var{c}} can be thought
8556 of as: if @var{a} then @var{b} else @var{c}. @var{a} should be of an
8560 Logical @sc{or}. Defined on integral types.
8563 Logical @sc{and}. Defined on integral types.
8566 Bitwise @sc{or}. Defined on integral types.
8569 Bitwise exclusive-@sc{or}. Defined on integral types.
8572 Bitwise @sc{and}. Defined on integral types.
8575 Equality and inequality. Defined on scalar types. The value of these
8576 expressions is 0 for false and non-zero for true.
8578 @item <@r{, }>@r{, }<=@r{, }>=
8579 Less than, greater than, less than or equal, greater than or equal.
8580 Defined on scalar types. The value of these expressions is 0 for false
8581 and non-zero for true.
8584 left shift, and right shift. Defined on integral types.
8587 The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}).
8590 Addition and subtraction. Defined on integral types, floating-point types and
8593 @item *@r{, }/@r{, }%
8594 Multiplication, division, and modulus. Multiplication and division are
8595 defined on integral and floating-point types. Modulus is defined on
8599 Increment and decrement. When appearing before a variable, the
8600 operation is performed before the variable is used in an expression;
8601 when appearing after it, the variable's value is used before the
8602 operation takes place.
8605 Pointer dereferencing. Defined on pointer types. Same precedence as
8609 Address operator. Defined on variables. Same precedence as @code{++}.
8611 For debugging C@t{++}, @value{GDBN} implements a use of @samp{&} beyond what is
8612 allowed in the C@t{++} language itself: you can use @samp{&(&@var{ref})}
8613 (or, if you prefer, simply @samp{&&@var{ref}}) to examine the address
8614 where a C@t{++} reference variable (declared with @samp{&@var{ref}}) is
8618 Negative. Defined on integral and floating-point types. Same
8619 precedence as @code{++}.
8622 Logical negation. Defined on integral types. Same precedence as
8626 Bitwise complement operator. Defined on integral types. Same precedence as
8631 Structure member, and pointer-to-structure member. For convenience,
8632 @value{GDBN} regards the two as equivalent, choosing whether to dereference a
8633 pointer based on the stored type information.
8634 Defined on @code{struct} and @code{union} data.
8637 Dereferences of pointers to members.
8640 Array indexing. @code{@var{a}[@var{i}]} is defined as
8641 @code{*(@var{a}+@var{i})}. Same precedence as @code{->}.
8644 Function parameter list. Same precedence as @code{->}.
8647 C@t{++} scope resolution operator. Defined on @code{struct}, @code{union},
8648 and @code{class} types.
8651 Doubled colons also represent the @value{GDBN} scope operator
8652 (@pxref{Expressions, ,Expressions}). Same precedence as @code{::},
8656 If an operator is redefined in the user code, @value{GDBN} usually
8657 attempts to invoke the redefined version instead of using the operator's
8665 @subsubsection C and C@t{++} constants
8667 @cindex C and C@t{++} constants
8669 @value{GDBN} allows you to express the constants of C and C@t{++} in the
8674 Integer constants are a sequence of digits. Octal constants are
8675 specified by a leading @samp{0} (i.e.@: zero), and hexadecimal constants
8676 by a leading @samp{0x} or @samp{0X}. Constants may also end with a letter
8677 @samp{l}, specifying that the constant should be treated as a
8681 Floating point constants are a sequence of digits, followed by a decimal
8682 point, followed by a sequence of digits, and optionally followed by an
8683 exponent. An exponent is of the form:
8684 @samp{@w{e@r{[[}+@r{]|}-@r{]}@var{nnn}}}, where @var{nnn} is another
8685 sequence of digits. The @samp{+} is optional for positive exponents.
8686 A floating-point constant may also end with a letter @samp{f} or
8687 @samp{F}, specifying that the constant should be treated as being of
8688 the @code{float} (as opposed to the default @code{double}) type; or with
8689 a letter @samp{l} or @samp{L}, which specifies a @code{long double}
8693 Enumerated constants consist of enumerated identifiers, or their
8694 integral equivalents.
8697 Character constants are a single character surrounded by single quotes
8698 (@code{'}), or a number---the ordinal value of the corresponding character
8699 (usually its @sc{ascii} value). Within quotes, the single character may
8700 be represented by a letter or by @dfn{escape sequences}, which are of
8701 the form @samp{\@var{nnn}}, where @var{nnn} is the octal representation
8702 of the character's ordinal value; or of the form @samp{\@var{x}}, where
8703 @samp{@var{x}} is a predefined special character---for example,
8704 @samp{\n} for newline.
8707 String constants are a sequence of character constants surrounded by
8708 double quotes (@code{"}). Any valid character constant (as described
8709 above) may appear. Double quotes within the string must be preceded by
8710 a backslash, so for instance @samp{"a\"b'c"} is a string of five
8714 Pointer constants are an integral value. You can also write pointers
8715 to constants using the C operator @samp{&}.
8718 Array constants are comma-separated lists surrounded by braces @samp{@{}
8719 and @samp{@}}; for example, @samp{@{1,2,3@}} is a three-element array of
8720 integers, @samp{@{@{1,2@}, @{3,4@}, @{5,6@}@}} is a three-by-two array,
8721 and @samp{@{&"hi", &"there", &"fred"@}} is a three-element array of pointers.
8725 * C plus plus expressions::
8732 @node C plus plus expressions
8733 @subsubsection C@t{++} expressions
8735 @cindex expressions in C@t{++}
8736 @value{GDBN} expression handling can interpret most C@t{++} expressions.
8738 @cindex debugging C@t{++} programs
8739 @cindex C@t{++} compilers
8740 @cindex debug formats and C@t{++}
8741 @cindex @value{NGCC} and C@t{++}
8743 @emph{Warning:} @value{GDBN} can only debug C@t{++} code if you use the
8744 proper compiler and the proper debug format. Currently, @value{GDBN}
8745 works best when debugging C@t{++} code that is compiled with
8746 @value{NGCC} 2.95.3 or with @value{NGCC} 3.1 or newer, using the options
8747 @option{-gdwarf-2} or @option{-gstabs+}. DWARF 2 is preferred over
8748 stabs+. Most configurations of @value{NGCC} emit either DWARF 2 or
8749 stabs+ as their default debug format, so you usually don't need to
8750 specify a debug format explicitly. Other compilers and/or debug formats
8751 are likely to work badly or not at all when using @value{GDBN} to debug
8757 @cindex member functions
8759 Member function calls are allowed; you can use expressions like
8762 count = aml->GetOriginal(x, y)
8765 @vindex this@r{, inside C@t{++} member functions}
8766 @cindex namespace in C@t{++}
8768 While a member function is active (in the selected stack frame), your
8769 expressions have the same namespace available as the member function;
8770 that is, @value{GDBN} allows implicit references to the class instance
8771 pointer @code{this} following the same rules as C@t{++}.
8773 @cindex call overloaded functions
8774 @cindex overloaded functions, calling
8775 @cindex type conversions in C@t{++}
8777 You can call overloaded functions; @value{GDBN} resolves the function
8778 call to the right definition, with some restrictions. @value{GDBN} does not
8779 perform overload resolution involving user-defined type conversions,
8780 calls to constructors, or instantiations of templates that do not exist
8781 in the program. It also cannot handle ellipsis argument lists or
8784 It does perform integral conversions and promotions, floating-point
8785 promotions, arithmetic conversions, pointer conversions, conversions of
8786 class objects to base classes, and standard conversions such as those of
8787 functions or arrays to pointers; it requires an exact match on the
8788 number of function arguments.
8790 Overload resolution is always performed, unless you have specified
8791 @code{set overload-resolution off}. @xref{Debugging C plus plus,
8792 ,@value{GDBN} features for C@t{++}}.
8794 You must specify @code{set overload-resolution off} in order to use an
8795 explicit function signature to call an overloaded function, as in
8797 p 'foo(char,int)'('x', 13)
8800 The @value{GDBN} command-completion facility can simplify this;
8801 see @ref{Completion, ,Command completion}.
8803 @cindex reference declarations
8805 @value{GDBN} understands variables declared as C@t{++} references; you can use
8806 them in expressions just as you do in C@t{++} source---they are automatically
8809 In the parameter list shown when @value{GDBN} displays a frame, the values of
8810 reference variables are not displayed (unlike other variables); this
8811 avoids clutter, since references are often used for large structures.
8812 The @emph{address} of a reference variable is always shown, unless
8813 you have specified @samp{set print address off}.
8816 @value{GDBN} supports the C@t{++} name resolution operator @code{::}---your
8817 expressions can use it just as expressions in your program do. Since
8818 one scope may be defined in another, you can use @code{::} repeatedly if
8819 necessary, for example in an expression like
8820 @samp{@var{scope1}::@var{scope2}::@var{name}}. @value{GDBN} also allows
8821 resolving name scope by reference to source files, in both C and C@t{++}
8822 debugging (@pxref{Variables, ,Program variables}).
8825 In addition, when used with HP's C@t{++} compiler, @value{GDBN} supports
8826 calling virtual functions correctly, printing out virtual bases of
8827 objects, calling functions in a base subobject, casting objects, and
8828 invoking user-defined operators.
8831 @subsubsection C and C@t{++} defaults
8833 @cindex C and C@t{++} defaults
8835 If you allow @value{GDBN} to set type and range checking automatically, they
8836 both default to @code{off} whenever the working language changes to
8837 C or C@t{++}. This happens regardless of whether you or @value{GDBN}
8838 selects the working language.
8840 If you allow @value{GDBN} to set the language automatically, it
8841 recognizes source files whose names end with @file{.c}, @file{.C}, or
8842 @file{.cc}, etc, and when @value{GDBN} enters code compiled from one of
8843 these files, it sets the working language to C or C@t{++}.
8844 @xref{Automatically, ,Having @value{GDBN} infer the source language},
8845 for further details.
8847 @c Type checking is (a) primarily motivated by Modula-2, and (b)
8848 @c unimplemented. If (b) changes, it might make sense to let this node
8849 @c appear even if Mod-2 does not, but meanwhile ignore it. roland 16jul93.
8852 @subsubsection C and C@t{++} type and range checks
8854 @cindex C and C@t{++} checks
8856 By default, when @value{GDBN} parses C or C@t{++} expressions, type checking
8857 is not used. However, if you turn type checking on, @value{GDBN}
8858 considers two variables type equivalent if:
8862 The two variables are structured and have the same structure, union, or
8866 The two variables have the same type name, or types that have been
8867 declared equivalent through @code{typedef}.
8870 @c leaving this out because neither J Gilmore nor R Pesch understand it.
8873 The two @code{struct}, @code{union}, or @code{enum} variables are
8874 declared in the same declaration. (Note: this may not be true for all C
8879 Range checking, if turned on, is done on mathematical operations. Array
8880 indices are not checked, since they are often used to index a pointer
8881 that is not itself an array.
8884 @subsubsection @value{GDBN} and C
8886 The @code{set print union} and @code{show print union} commands apply to
8887 the @code{union} type. When set to @samp{on}, any @code{union} that is
8888 inside a @code{struct} or @code{class} is also printed. Otherwise, it
8889 appears as @samp{@{...@}}.
8891 The @code{@@} operator aids in the debugging of dynamic arrays, formed
8892 with pointers and a memory allocation function. @xref{Expressions,
8896 * Debugging C plus plus::
8899 @node Debugging C plus plus
8900 @subsubsection @value{GDBN} features for C@t{++}
8902 @cindex commands for C@t{++}
8904 Some @value{GDBN} commands are particularly useful with C@t{++}, and some are
8905 designed specifically for use with C@t{++}. Here is a summary:
8908 @cindex break in overloaded functions
8909 @item @r{breakpoint menus}
8910 When you want a breakpoint in a function whose name is overloaded,
8911 @value{GDBN} breakpoint menus help you specify which function definition
8912 you want. @xref{Breakpoint Menus,,Breakpoint menus}.
8914 @cindex overloading in C@t{++}
8915 @item rbreak @var{regex}
8916 Setting breakpoints using regular expressions is helpful for setting
8917 breakpoints on overloaded functions that are not members of any special
8919 @xref{Set Breaks, ,Setting breakpoints}.
8921 @cindex C@t{++} exception handling
8924 Debug C@t{++} exception handling using these commands. @xref{Set
8925 Catchpoints, , Setting catchpoints}.
8928 @item ptype @var{typename}
8929 Print inheritance relationships as well as other information for type
8931 @xref{Symbols, ,Examining the Symbol Table}.
8933 @cindex C@t{++} symbol display
8934 @item set print demangle
8935 @itemx show print demangle
8936 @itemx set print asm-demangle
8937 @itemx show print asm-demangle
8938 Control whether C@t{++} symbols display in their source form, both when
8939 displaying code as C@t{++} source and when displaying disassemblies.
8940 @xref{Print Settings, ,Print settings}.
8942 @item set print object
8943 @itemx show print object
8944 Choose whether to print derived (actual) or declared types of objects.
8945 @xref{Print Settings, ,Print settings}.
8947 @item set print vtbl
8948 @itemx show print vtbl
8949 Control the format for printing virtual function tables.
8950 @xref{Print Settings, ,Print settings}.
8951 (The @code{vtbl} commands do not work on programs compiled with the HP
8952 ANSI C@t{++} compiler (@code{aCC}).)
8954 @kindex set overload-resolution
8955 @cindex overloaded functions, overload resolution
8956 @item set overload-resolution on
8957 Enable overload resolution for C@t{++} expression evaluation. The default
8958 is on. For overloaded functions, @value{GDBN} evaluates the arguments
8959 and searches for a function whose signature matches the argument types,
8960 using the standard C@t{++} conversion rules (see @ref{C plus plus expressions, ,C@t{++}
8961 expressions}, for details). If it cannot find a match, it emits a
8964 @item set overload-resolution off
8965 Disable overload resolution for C@t{++} expression evaluation. For
8966 overloaded functions that are not class member functions, @value{GDBN}
8967 chooses the first function of the specified name that it finds in the
8968 symbol table, whether or not its arguments are of the correct type. For
8969 overloaded functions that are class member functions, @value{GDBN}
8970 searches for a function whose signature @emph{exactly} matches the
8973 @kindex show overload-resolution
8974 @item show overload-resolution
8975 Show the current setting of overload resolution.
8977 @item @r{Overloaded symbol names}
8978 You can specify a particular definition of an overloaded symbol, using
8979 the same notation that is used to declare such symbols in C@t{++}: type
8980 @code{@var{symbol}(@var{types})} rather than just @var{symbol}. You can
8981 also use the @value{GDBN} command-line word completion facilities to list the
8982 available choices, or to finish the type list for you.
8983 @xref{Completion,, Command completion}, for details on how to do this.
8987 @subsection Objective-C
8990 This section provides information about some commands and command
8991 options that are useful for debugging Objective-C code. See also
8992 @ref{Symbols, info classes}, and @ref{Symbols, info selectors}, for a
8993 few more commands specific to Objective-C support.
8996 * Method Names in Commands::
8997 * The Print Command with Objective-C::
9000 @node Method Names in Commands, The Print Command with Objective-C, Objective-C, Objective-C
9001 @subsubsection Method Names in Commands
9003 The following commands have been extended to accept Objective-C method
9004 names as line specifications:
9006 @kindex clear@r{, and Objective-C}
9007 @kindex break@r{, and Objective-C}
9008 @kindex info line@r{, and Objective-C}
9009 @kindex jump@r{, and Objective-C}
9010 @kindex list@r{, and Objective-C}
9014 @item @code{info line}
9019 A fully qualified Objective-C method name is specified as
9022 -[@var{Class} @var{methodName}]
9025 where the minus sign is used to indicate an instance method and a
9026 plus sign (not shown) is used to indicate a class method. The class
9027 name @var{Class} and method name @var{methodName} are enclosed in
9028 brackets, similar to the way messages are specified in Objective-C
9029 source code. For example, to set a breakpoint at the @code{create}
9030 instance method of class @code{Fruit} in the program currently being
9034 break -[Fruit create]
9037 To list ten program lines around the @code{initialize} class method,
9041 list +[NSText initialize]
9044 In the current version of @value{GDBN}, the plus or minus sign is
9045 required. In future versions of @value{GDBN}, the plus or minus
9046 sign will be optional, but you can use it to narrow the search. It
9047 is also possible to specify just a method name:
9053 You must specify the complete method name, including any colons. If
9054 your program's source files contain more than one @code{create} method,
9055 you'll be presented with a numbered list of classes that implement that
9056 method. Indicate your choice by number, or type @samp{0} to exit if
9059 As another example, to clear a breakpoint established at the
9060 @code{makeKeyAndOrderFront:} method of the @code{NSWindow} class, enter:
9063 clear -[NSWindow makeKeyAndOrderFront:]
9066 @node The Print Command with Objective-C
9067 @subsubsection The Print Command With Objective-C
9068 @cindex Objective-C, print objects
9069 @kindex print-object
9070 @kindex po @r{(@code{print-object})}
9072 The print command has also been extended to accept methods. For example:
9075 print -[@var{object} hash]
9078 @cindex print an Objective-C object description
9079 @cindex @code{_NSPrintForDebugger}, and printing Objective-C objects
9081 will tell @value{GDBN} to send the @code{hash} message to @var{object}
9082 and print the result. Also, an additional command has been added,
9083 @code{print-object} or @code{po} for short, which is meant to print
9084 the description of an object. However, this command may only work
9085 with certain Objective-C libraries that have a particular hook
9086 function, @code{_NSPrintForDebugger}, defined.
9090 @cindex Fortran-specific support in @value{GDBN}
9093 @cindex @code{COMMON} blocks, Fortran
9095 @item info common @r{[}@var{common-name}@r{]}
9096 This command prints the values contained in the Fortran @code{COMMON}
9097 block whose name is @var{common-name}. With no argument, the names of
9098 all @code{COMMON} blocks visible at current program location are
9102 Fortran symbols are usually case-insensitive, so @value{GDBN} by
9103 default uses case-insensitive matches for Fortran symbols. You can
9104 change that with the @samp{set case-insensitive} command, see
9105 @ref{Symbols}, for the details.
9110 @cindex Pascal support in @value{GDBN}, limitations
9111 Debugging Pascal programs which use sets, subranges, file variables, or
9112 nested functions does not currently work. @value{GDBN} does not support
9113 entering expressions, printing values, or similar features using Pascal
9116 The Pascal-specific command @code{set print pascal_static-members}
9117 controls whether static members of Pascal objects are displayed.
9118 @xref{Print Settings, pascal_static-members}.
9121 @subsection Modula-2
9123 @cindex Modula-2, @value{GDBN} support
9125 The extensions made to @value{GDBN} to support Modula-2 only support
9126 output from the @sc{gnu} Modula-2 compiler (which is currently being
9127 developed). Other Modula-2 compilers are not currently supported, and
9128 attempting to debug executables produced by them is most likely
9129 to give an error as @value{GDBN} reads in the executable's symbol
9132 @cindex expressions in Modula-2
9134 * M2 Operators:: Built-in operators
9135 * Built-In Func/Proc:: Built-in functions and procedures
9136 * M2 Constants:: Modula-2 constants
9137 * M2 Defaults:: Default settings for Modula-2
9138 * Deviations:: Deviations from standard Modula-2
9139 * M2 Checks:: Modula-2 type and range checks
9140 * M2 Scope:: The scope operators @code{::} and @code{.}
9141 * GDB/M2:: @value{GDBN} and Modula-2
9145 @subsubsection Operators
9146 @cindex Modula-2 operators
9148 Operators must be defined on values of specific types. For instance,
9149 @code{+} is defined on numbers, but not on structures. Operators are
9150 often defined on groups of types. For the purposes of Modula-2, the
9151 following definitions hold:
9156 @emph{Integral types} consist of @code{INTEGER}, @code{CARDINAL}, and
9160 @emph{Character types} consist of @code{CHAR} and its subranges.
9163 @emph{Floating-point types} consist of @code{REAL}.
9166 @emph{Pointer types} consist of anything declared as @code{POINTER TO
9170 @emph{Scalar types} consist of all of the above.
9173 @emph{Set types} consist of @code{SET} and @code{BITSET} types.
9176 @emph{Boolean types} consist of @code{BOOLEAN}.
9180 The following operators are supported, and appear in order of
9181 increasing precedence:
9185 Function argument or array index separator.
9188 Assignment. The value of @var{var} @code{:=} @var{value} is
9192 Less than, greater than on integral, floating-point, or enumerated
9196 Less than or equal to, greater than or equal to
9197 on integral, floating-point and enumerated types, or set inclusion on
9198 set types. Same precedence as @code{<}.
9200 @item =@r{, }<>@r{, }#
9201 Equality and two ways of expressing inequality, valid on scalar types.
9202 Same precedence as @code{<}. In @value{GDBN} scripts, only @code{<>} is
9203 available for inequality, since @code{#} conflicts with the script
9207 Set membership. Defined on set types and the types of their members.
9208 Same precedence as @code{<}.
9211 Boolean disjunction. Defined on boolean types.
9214 Boolean conjunction. Defined on boolean types.
9217 The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}).
9220 Addition and subtraction on integral and floating-point types, or union
9221 and difference on set types.
9224 Multiplication on integral and floating-point types, or set intersection
9228 Division on floating-point types, or symmetric set difference on set
9229 types. Same precedence as @code{*}.
9232 Integer division and remainder. Defined on integral types. Same
9233 precedence as @code{*}.
9236 Negative. Defined on @code{INTEGER} and @code{REAL} data.
9239 Pointer dereferencing. Defined on pointer types.
9242 Boolean negation. Defined on boolean types. Same precedence as
9246 @code{RECORD} field selector. Defined on @code{RECORD} data. Same
9247 precedence as @code{^}.
9250 Array indexing. Defined on @code{ARRAY} data. Same precedence as @code{^}.
9253 Procedure argument list. Defined on @code{PROCEDURE} objects. Same precedence
9257 @value{GDBN} and Modula-2 scope operators.
9261 @emph{Warning:} Sets and their operations are not yet supported, so @value{GDBN}
9262 treats the use of the operator @code{IN}, or the use of operators
9263 @code{+}, @code{-}, @code{*}, @code{/}, @code{=}, , @code{<>}, @code{#},
9264 @code{<=}, and @code{>=} on sets as an error.
9268 @node Built-In Func/Proc
9269 @subsubsection Built-in functions and procedures
9270 @cindex Modula-2 built-ins
9272 Modula-2 also makes available several built-in procedures and functions.
9273 In describing these, the following metavariables are used:
9278 represents an @code{ARRAY} variable.
9281 represents a @code{CHAR} constant or variable.
9284 represents a variable or constant of integral type.
9287 represents an identifier that belongs to a set. Generally used in the
9288 same function with the metavariable @var{s}. The type of @var{s} should
9289 be @code{SET OF @var{mtype}} (where @var{mtype} is the type of @var{m}).
9292 represents a variable or constant of integral or floating-point type.
9295 represents a variable or constant of floating-point type.
9301 represents a variable.
9304 represents a variable or constant of one of many types. See the
9305 explanation of the function for details.
9308 All Modula-2 built-in procedures also return a result, described below.
9312 Returns the absolute value of @var{n}.
9315 If @var{c} is a lower case letter, it returns its upper case
9316 equivalent, otherwise it returns its argument.
9319 Returns the character whose ordinal value is @var{i}.
9322 Decrements the value in the variable @var{v} by one. Returns the new value.
9324 @item DEC(@var{v},@var{i})
9325 Decrements the value in the variable @var{v} by @var{i}. Returns the
9328 @item EXCL(@var{m},@var{s})
9329 Removes the element @var{m} from the set @var{s}. Returns the new
9332 @item FLOAT(@var{i})
9333 Returns the floating point equivalent of the integer @var{i}.
9336 Returns the index of the last member of @var{a}.
9339 Increments the value in the variable @var{v} by one. Returns the new value.
9341 @item INC(@var{v},@var{i})
9342 Increments the value in the variable @var{v} by @var{i}. Returns the
9345 @item INCL(@var{m},@var{s})
9346 Adds the element @var{m} to the set @var{s} if it is not already
9347 there. Returns the new set.
9350 Returns the maximum value of the type @var{t}.
9353 Returns the minimum value of the type @var{t}.
9356 Returns boolean TRUE if @var{i} is an odd number.
9359 Returns the ordinal value of its argument. For example, the ordinal
9360 value of a character is its @sc{ascii} value (on machines supporting the
9361 @sc{ascii} character set). @var{x} must be of an ordered type, which include
9362 integral, character and enumerated types.
9365 Returns the size of its argument. @var{x} can be a variable or a type.
9367 @item TRUNC(@var{r})
9368 Returns the integral part of @var{r}.
9370 @item VAL(@var{t},@var{i})
9371 Returns the member of the type @var{t} whose ordinal value is @var{i}.
9375 @emph{Warning:} Sets and their operations are not yet supported, so
9376 @value{GDBN} treats the use of procedures @code{INCL} and @code{EXCL} as
9380 @cindex Modula-2 constants
9382 @subsubsection Constants
9384 @value{GDBN} allows you to express the constants of Modula-2 in the following
9390 Integer constants are simply a sequence of digits. When used in an
9391 expression, a constant is interpreted to be type-compatible with the
9392 rest of the expression. Hexadecimal integers are specified by a
9393 trailing @samp{H}, and octal integers by a trailing @samp{B}.
9396 Floating point constants appear as a sequence of digits, followed by a
9397 decimal point and another sequence of digits. An optional exponent can
9398 then be specified, in the form @samp{E@r{[}+@r{|}-@r{]}@var{nnn}}, where
9399 @samp{@r{[}+@r{|}-@r{]}@var{nnn}} is the desired exponent. All of the
9400 digits of the floating point constant must be valid decimal (base 10)
9404 Character constants consist of a single character enclosed by a pair of
9405 like quotes, either single (@code{'}) or double (@code{"}). They may
9406 also be expressed by their ordinal value (their @sc{ascii} value, usually)
9407 followed by a @samp{C}.
9410 String constants consist of a sequence of characters enclosed by a
9411 pair of like quotes, either single (@code{'}) or double (@code{"}).
9412 Escape sequences in the style of C are also allowed. @xref{C
9413 Constants, ,C and C@t{++} constants}, for a brief explanation of escape
9417 Enumerated constants consist of an enumerated identifier.
9420 Boolean constants consist of the identifiers @code{TRUE} and
9424 Pointer constants consist of integral values only.
9427 Set constants are not yet supported.
9431 @subsubsection Modula-2 defaults
9432 @cindex Modula-2 defaults
9434 If type and range checking are set automatically by @value{GDBN}, they
9435 both default to @code{on} whenever the working language changes to
9436 Modula-2. This happens regardless of whether you or @value{GDBN}
9437 selected the working language.
9439 If you allow @value{GDBN} to set the language automatically, then entering
9440 code compiled from a file whose name ends with @file{.mod} sets the
9441 working language to Modula-2. @xref{Automatically, ,Having @value{GDBN} set
9442 the language automatically}, for further details.
9445 @subsubsection Deviations from standard Modula-2
9446 @cindex Modula-2, deviations from
9448 A few changes have been made to make Modula-2 programs easier to debug.
9449 This is done primarily via loosening its type strictness:
9453 Unlike in standard Modula-2, pointer constants can be formed by
9454 integers. This allows you to modify pointer variables during
9455 debugging. (In standard Modula-2, the actual address contained in a
9456 pointer variable is hidden from you; it can only be modified
9457 through direct assignment to another pointer variable or expression that
9458 returned a pointer.)
9461 C escape sequences can be used in strings and characters to represent
9462 non-printable characters. @value{GDBN} prints out strings with these
9463 escape sequences embedded. Single non-printable characters are
9464 printed using the @samp{CHR(@var{nnn})} format.
9467 The assignment operator (@code{:=}) returns the value of its right-hand
9471 All built-in procedures both modify @emph{and} return their argument.
9475 @subsubsection Modula-2 type and range checks
9476 @cindex Modula-2 checks
9479 @emph{Warning:} in this release, @value{GDBN} does not yet perform type or
9482 @c FIXME remove warning when type/range checks added
9484 @value{GDBN} considers two Modula-2 variables type equivalent if:
9488 They are of types that have been declared equivalent via a @code{TYPE
9489 @var{t1} = @var{t2}} statement
9492 They have been declared on the same line. (Note: This is true of the
9493 @sc{gnu} Modula-2 compiler, but it may not be true of other compilers.)
9496 As long as type checking is enabled, any attempt to combine variables
9497 whose types are not equivalent is an error.
9499 Range checking is done on all mathematical operations, assignment, array
9500 index bounds, and all built-in functions and procedures.
9503 @subsubsection The scope operators @code{::} and @code{.}
9505 @cindex @code{.}, Modula-2 scope operator
9506 @cindex colon, doubled as scope operator
9508 @vindex colon-colon@r{, in Modula-2}
9509 @c Info cannot handle :: but TeX can.
9512 @vindex ::@r{, in Modula-2}
9515 There are a few subtle differences between the Modula-2 scope operator
9516 (@code{.}) and the @value{GDBN} scope operator (@code{::}). The two have
9521 @var{module} . @var{id}
9522 @var{scope} :: @var{id}
9526 where @var{scope} is the name of a module or a procedure,
9527 @var{module} the name of a module, and @var{id} is any declared
9528 identifier within your program, except another module.
9530 Using the @code{::} operator makes @value{GDBN} search the scope
9531 specified by @var{scope} for the identifier @var{id}. If it is not
9532 found in the specified scope, then @value{GDBN} searches all scopes
9533 enclosing the one specified by @var{scope}.
9535 Using the @code{.} operator makes @value{GDBN} search the current scope for
9536 the identifier specified by @var{id} that was imported from the
9537 definition module specified by @var{module}. With this operator, it is
9538 an error if the identifier @var{id} was not imported from definition
9539 module @var{module}, or if @var{id} is not an identifier in
9543 @subsubsection @value{GDBN} and Modula-2
9545 Some @value{GDBN} commands have little use when debugging Modula-2 programs.
9546 Five subcommands of @code{set print} and @code{show print} apply
9547 specifically to C and C@t{++}: @samp{vtbl}, @samp{demangle},
9548 @samp{asm-demangle}, @samp{object}, and @samp{union}. The first four
9549 apply to C@t{++}, and the last to the C @code{union} type, which has no direct
9550 analogue in Modula-2.
9552 The @code{@@} operator (@pxref{Expressions, ,Expressions}), while available
9553 with any language, is not useful with Modula-2. Its
9554 intent is to aid the debugging of @dfn{dynamic arrays}, which cannot be
9555 created in Modula-2 as they can in C or C@t{++}. However, because an
9556 address can be specified by an integral constant, the construct
9557 @samp{@{@var{type}@}@var{adrexp}} is still useful.
9559 @cindex @code{#} in Modula-2
9560 In @value{GDBN} scripts, the Modula-2 inequality operator @code{#} is
9561 interpreted as the beginning of a comment. Use @code{<>} instead.
9567 The extensions made to @value{GDBN} for Ada only support
9568 output from the @sc{gnu} Ada (GNAT) compiler.
9569 Other Ada compilers are not currently supported, and
9570 attempting to debug executables produced by them is most likely
9574 @cindex expressions in Ada
9576 * Ada Mode Intro:: General remarks on the Ada syntax
9577 and semantics supported by Ada mode
9579 * Omissions from Ada:: Restrictions on the Ada expression syntax.
9580 * Additions to Ada:: Extensions of the Ada expression syntax.
9581 * Stopping Before Main Program:: Debugging the program during elaboration.
9582 * Ada Glitches:: Known peculiarities of Ada mode.
9585 @node Ada Mode Intro
9586 @subsubsection Introduction
9587 @cindex Ada mode, general
9589 The Ada mode of @value{GDBN} supports a fairly large subset of Ada expression
9590 syntax, with some extensions.
9591 The philosophy behind the design of this subset is
9595 That @value{GDBN} should provide basic literals and access to operations for
9596 arithmetic, dereferencing, field selection, indexing, and subprogram calls,
9597 leaving more sophisticated computations to subprograms written into the
9598 program (which therefore may be called from @value{GDBN}).
9601 That type safety and strict adherence to Ada language restrictions
9602 are not particularly important to the @value{GDBN} user.
9605 That brevity is important to the @value{GDBN} user.
9608 Thus, for brevity, the debugger acts as if there were
9609 implicit @code{with} and @code{use} clauses in effect for all user-written
9610 packages, making it unnecessary to fully qualify most names with
9611 their packages, regardless of context. Where this causes ambiguity,
9612 @value{GDBN} asks the user's intent.
9614 The debugger will start in Ada mode if it detects an Ada main program.
9615 As for other languages, it will enter Ada mode when stopped in a program that
9616 was translated from an Ada source file.
9618 While in Ada mode, you may use `@t{--}' for comments. This is useful
9619 mostly for documenting command files. The standard @value{GDBN} comment
9620 (@samp{#}) still works at the beginning of a line in Ada mode, but not in the
9621 middle (to allow based literals).
9623 The debugger supports limited overloading. Given a subprogram call in which
9624 the function symbol has multiple definitions, it will use the number of
9625 actual parameters and some information about their types to attempt to narrow
9626 the set of definitions. It also makes very limited use of context, preferring
9627 procedures to functions in the context of the @code{call} command, and
9628 functions to procedures elsewhere.
9630 @node Omissions from Ada
9631 @subsubsection Omissions from Ada
9632 @cindex Ada, omissions from
9634 Here are the notable omissions from the subset:
9638 Only a subset of the attributes are supported:
9642 @t{'First}, @t{'Last}, and @t{'Length}
9643 on array objects (not on types and subtypes).
9646 @t{'Min} and @t{'Max}.
9649 @t{'Pos} and @t{'Val}.
9655 @t{'Range} on array objects (not subtypes), but only as the right
9656 operand of the membership (@code{in}) operator.
9659 @t{'Access}, @t{'Unchecked_Access}, and
9660 @t{'Unrestricted_Access} (a GNAT extension).
9668 @code{Characters.Latin_1} are not available and
9669 concatenation is not implemented. Thus, escape characters in strings are
9670 not currently available.
9673 Equality tests (@samp{=} and @samp{/=}) on arrays test for bitwise
9674 equality of representations. They will generally work correctly
9675 for strings and arrays whose elements have integer or enumeration types.
9676 They may not work correctly for arrays whose element
9677 types have user-defined equality, for arrays of real values
9678 (in particular, IEEE-conformant floating point, because of negative
9679 zeroes and NaNs), and for arrays whose elements contain unused bits with
9680 indeterminate values.
9683 The other component-by-component array operations (@code{and}, @code{or},
9684 @code{xor}, @code{not}, and relational tests other than equality)
9685 are not implemented.
9688 There are no record or array aggregates.
9691 Calls to dispatching subprograms are not implemented.
9694 The overloading algorithm is much more limited (i.e., less selective)
9695 than that of real Ada. It makes only limited use of the context in which a subexpression
9696 appears to resolve its meaning, and it is much looser in its rules for allowing
9697 type matches. As a result, some function calls will be ambiguous, and the user
9698 will be asked to choose the proper resolution.
9701 The @code{new} operator is not implemented.
9704 Entry calls are not implemented.
9707 Aside from printing, arithmetic operations on the native VAX floating-point
9708 formats are not supported.
9711 It is not possible to slice a packed array.
9714 @node Additions to Ada
9715 @subsubsection Additions to Ada
9716 @cindex Ada, deviations from
9718 As it does for other languages, @value{GDBN} makes certain generic
9719 extensions to Ada (@pxref{Expressions}):
9723 If the expression @var{E} is a variable residing in memory
9724 (typically a local variable or array element) and @var{N} is
9725 a positive integer, then @code{@var{E}@@@var{N}} displays the values of
9726 @var{E} and the @var{N}-1 adjacent variables following it in memory as an array.
9727 In Ada, this operator is generally not necessary, since its prime use
9728 is in displaying parts of an array, and slicing will usually do this in Ada.
9729 However, there are occasional uses when debugging programs
9730 in which certain debugging information has been optimized away.
9733 @code{@var{B}::@var{var}} means ``the variable named @var{var} that appears
9734 in function or file @var{B}.'' When @var{B} is a file name, you must typically
9735 surround it in single quotes.
9738 The expression @code{@{@var{type}@} @var{addr}} means ``the variable of type
9739 @var{type} that appears at address @var{addr}.''
9742 A name starting with @samp{$} is a convenience variable
9743 (@pxref{Convenience Vars}) or a machine register (@pxref{Registers}).
9746 In addition, @value{GDBN} provides a few other shortcuts and outright additions specific
9751 The assignment statement is allowed as an expression, returning
9752 its right-hand operand as its value. Thus, you may enter
9756 print A(tmp := y + 1)
9760 The semicolon is allowed as an ``operator,'' returning as its value
9761 the value of its right-hand operand.
9762 This allows, for example,
9763 complex conditional breaks:
9767 condition 1 (report(i); k += 1; A(k) > 100)
9771 Rather than use catenation and symbolic character names to introduce special
9772 characters into strings, one may instead use a special bracket notation,
9773 which is also used to print strings. A sequence of characters of the form
9774 @samp{["@var{XX}"]} within a string or character literal denotes the
9775 (single) character whose numeric encoding is @var{XX} in hexadecimal. The
9776 sequence of characters @samp{["""]} also denotes a single quotation mark
9777 in strings. For example,
9779 "One line.["0a"]Next line.["0a"]"
9782 contains an ASCII newline character (@code{Ada.Characters.Latin_1.LF}) after each
9786 The subtype used as a prefix for the attributes @t{'Pos}, @t{'Min}, and
9787 @t{'Max} is optional (and is ignored in any case). For example, it is valid
9795 When printing arrays, @value{GDBN} uses positional notation when the
9796 array has a lower bound of 1, and uses a modified named notation otherwise.
9797 For example, a one-dimensional array of three integers with a lower bound of 3 might print as
9804 That is, in contrast to valid Ada, only the first component has a @code{=>}
9808 You may abbreviate attributes in expressions with any unique,
9809 multi-character subsequence of
9810 their names (an exact match gets preference).
9811 For example, you may use @t{a'len}, @t{a'gth}, or @t{a'lh}
9812 in place of @t{a'length}.
9815 @cindex quoting Ada internal identifiers
9816 Since Ada is case-insensitive, the debugger normally maps identifiers you type
9817 to lower case. The GNAT compiler uses upper-case characters for
9818 some of its internal identifiers, which are normally of no interest to users.
9819 For the rare occasions when you actually have to look at them,
9820 enclose them in angle brackets to avoid the lower-case mapping.
9823 @value{GDBP} print <JMPBUF_SAVE>[0]
9827 Printing an object of class-wide type or dereferencing an
9828 access-to-class-wide value will display all the components of the object's
9829 specific type (as indicated by its run-time tag). Likewise, component
9830 selection on such a value will operate on the specific type of the
9835 @node Stopping Before Main Program
9836 @subsubsection Stopping at the Very Beginning
9838 @cindex breakpointing Ada elaboration code
9839 It is sometimes necessary to debug the program during elaboration, and
9840 before reaching the main procedure.
9841 As defined in the Ada Reference
9842 Manual, the elaboration code is invoked from a procedure called
9843 @code{adainit}. To run your program up to the beginning of
9844 elaboration, simply use the following two commands:
9845 @code{tbreak adainit} and @code{run}.
9848 @subsubsection Known Peculiarities of Ada Mode
9849 @cindex Ada, problems
9851 Besides the omissions listed previously (@pxref{Omissions from Ada}),
9852 we know of several problems with and limitations of Ada mode in
9854 some of which will be fixed with planned future releases of the debugger
9855 and the GNU Ada compiler.
9859 Currently, the debugger
9860 has insufficient information to determine whether certain pointers represent
9861 pointers to objects or the objects themselves.
9862 Thus, the user may have to tack an extra @code{.all} after an expression
9863 to get it printed properly.
9866 Static constants that the compiler chooses not to materialize as objects in
9867 storage are invisible to the debugger.
9870 Named parameter associations in function argument lists are ignored (the
9871 argument lists are treated as positional).
9874 Many useful library packages are currently invisible to the debugger.
9877 Fixed-point arithmetic, conversions, input, and output is carried out using
9878 floating-point arithmetic, and may give results that only approximate those on
9882 The type of the @t{'Address} attribute may not be @code{System.Address}.
9885 The GNAT compiler never generates the prefix @code{Standard} for any of
9886 the standard symbols defined by the Ada language. @value{GDBN} knows about
9887 this: it will strip the prefix from names when you use it, and will never
9888 look for a name you have so qualified among local symbols, nor match against
9889 symbols in other packages or subprograms. If you have
9890 defined entities anywhere in your program other than parameters and
9891 local variables whose simple names match names in @code{Standard},
9892 GNAT's lack of qualification here can cause confusion. When this happens,
9893 you can usually resolve the confusion
9894 by qualifying the problematic names with package
9895 @code{Standard} explicitly.
9898 @node Unsupported languages
9899 @section Unsupported languages
9901 @cindex unsupported languages
9902 @cindex minimal language
9903 In addition to the other fully-supported programming languages,
9904 @value{GDBN} also provides a pseudo-language, called @code{minimal}.
9905 It does not represent a real programming language, but provides a set
9906 of capabilities close to what the C or assembly languages provide.
9907 This should allow most simple operations to be performed while debugging
9908 an application that uses a language currently not supported by @value{GDBN}.
9910 If the language is set to @code{auto}, @value{GDBN} will automatically
9911 select this language if the current frame corresponds to an unsupported
9915 @chapter Examining the Symbol Table
9917 The commands described in this chapter allow you to inquire about the
9918 symbols (names of variables, functions and types) defined in your
9919 program. This information is inherent in the text of your program and
9920 does not change as your program executes. @value{GDBN} finds it in your
9921 program's symbol table, in the file indicated when you started @value{GDBN}
9922 (@pxref{File Options, ,Choosing files}), or by one of the
9923 file-management commands (@pxref{Files, ,Commands to specify files}).
9925 @cindex symbol names
9926 @cindex names of symbols
9927 @cindex quoting names
9928 Occasionally, you may need to refer to symbols that contain unusual
9929 characters, which @value{GDBN} ordinarily treats as word delimiters. The
9930 most frequent case is in referring to static variables in other
9931 source files (@pxref{Variables,,Program variables}). File names
9932 are recorded in object files as debugging symbols, but @value{GDBN} would
9933 ordinarily parse a typical file name, like @file{foo.c}, as the three words
9934 @samp{foo} @samp{.} @samp{c}. To allow @value{GDBN} to recognize
9935 @samp{foo.c} as a single symbol, enclose it in single quotes; for example,
9942 looks up the value of @code{x} in the scope of the file @file{foo.c}.
9945 @cindex case-insensitive symbol names
9946 @cindex case sensitivity in symbol names
9947 @kindex set case-sensitive
9948 @item set case-sensitive on
9949 @itemx set case-sensitive off
9950 @itemx set case-sensitive auto
9951 Normally, when @value{GDBN} looks up symbols, it matches their names
9952 with case sensitivity determined by the current source language.
9953 Occasionally, you may wish to control that. The command @code{set
9954 case-sensitive} lets you do that by specifying @code{on} for
9955 case-sensitive matches or @code{off} for case-insensitive ones. If
9956 you specify @code{auto}, case sensitivity is reset to the default
9957 suitable for the source language. The default is case-sensitive
9958 matches for all languages except for Fortran, for which the default is
9959 case-insensitive matches.
9961 @kindex show case-sensitive
9962 @item show case-sensitive
9963 This command shows the current setting of case sensitivity for symbols
9966 @kindex info address
9967 @cindex address of a symbol
9968 @item info address @var{symbol}
9969 Describe where the data for @var{symbol} is stored. For a register
9970 variable, this says which register it is kept in. For a non-register
9971 local variable, this prints the stack-frame offset at which the variable
9974 Note the contrast with @samp{print &@var{symbol}}, which does not work
9975 at all for a register variable, and for a stack local variable prints
9976 the exact address of the current instantiation of the variable.
9979 @cindex symbol from address
9980 @cindex closest symbol and offset for an address
9981 @item info symbol @var{addr}
9982 Print the name of a symbol which is stored at the address @var{addr}.
9983 If no symbol is stored exactly at @var{addr}, @value{GDBN} prints the
9984 nearest symbol and an offset from it:
9987 (@value{GDBP}) info symbol 0x54320
9988 _initialize_vx + 396 in section .text
9992 This is the opposite of the @code{info address} command. You can use
9993 it to find out the name of a variable or a function given its address.
9996 @item whatis @var{expr}
9997 Print the data type of expression @var{expr}. @var{expr} is not
9998 actually evaluated, and any side-effecting operations (such as
9999 assignments or function calls) inside it do not take place.
10000 @xref{Expressions, ,Expressions}.
10003 Print the data type of @code{$}, the last value in the value history.
10006 @item ptype @var{typename}
10007 Print a description of data type @var{typename}. @var{typename} may be
10008 the name of a type, or for C code it may have the form @samp{class
10009 @var{class-name}}, @samp{struct @var{struct-tag}}, @samp{union
10010 @var{union-tag}} or @samp{enum @var{enum-tag}}.
10012 @item ptype @var{expr}
10014 Print a description of the type of expression @var{expr}. @code{ptype}
10015 differs from @code{whatis} by printing a detailed description, instead
10016 of just the name of the type.
10018 For example, for this variable declaration:
10021 struct complex @{double real; double imag;@} v;
10025 the two commands give this output:
10029 (@value{GDBP}) whatis v
10030 type = struct complex
10031 (@value{GDBP}) ptype v
10032 type = struct complex @{
10040 As with @code{whatis}, using @code{ptype} without an argument refers to
10041 the type of @code{$}, the last value in the value history.
10044 @item info types @var{regexp}
10046 Print a brief description of all types whose names match the regular
10047 expression @var{regexp} (or all types in your program, if you supply
10048 no argument). Each complete typename is matched as though it were a
10049 complete line; thus, @samp{i type value} gives information on all
10050 types in your program whose names include the string @code{value}, but
10051 @samp{i type ^value$} gives information only on types whose complete
10052 name is @code{value}.
10054 This command differs from @code{ptype} in two ways: first, like
10055 @code{whatis}, it does not print a detailed description; second, it
10056 lists all source files where a type is defined.
10059 @cindex local variables
10060 @item info scope @var{location}
10061 List all the variables local to a particular scope. This command
10062 accepts a @var{location} argument---a function name, a source line, or
10063 an address preceded by a @samp{*}, and prints all the variables local
10064 to the scope defined by that location. For example:
10067 (@value{GDBP}) @b{info scope command_line_handler}
10068 Scope for command_line_handler:
10069 Symbol rl is an argument at stack/frame offset 8, length 4.
10070 Symbol linebuffer is in static storage at address 0x150a18, length 4.
10071 Symbol linelength is in static storage at address 0x150a1c, length 4.
10072 Symbol p is a local variable in register $esi, length 4.
10073 Symbol p1 is a local variable in register $ebx, length 4.
10074 Symbol nline is a local variable in register $edx, length 4.
10075 Symbol repeat is a local variable at frame offset -8, length 4.
10079 This command is especially useful for determining what data to collect
10080 during a @dfn{trace experiment}, see @ref{Tracepoint Actions,
10083 @kindex info source
10085 Show information about the current source file---that is, the source file for
10086 the function containing the current point of execution:
10089 the name of the source file, and the directory containing it,
10091 the directory it was compiled in,
10093 its length, in lines,
10095 which programming language it is written in,
10097 whether the executable includes debugging information for that file, and
10098 if so, what format the information is in (e.g., STABS, Dwarf 2, etc.), and
10100 whether the debugging information includes information about
10101 preprocessor macros.
10105 @kindex info sources
10107 Print the names of all source files in your program for which there is
10108 debugging information, organized into two lists: files whose symbols
10109 have already been read, and files whose symbols will be read when needed.
10111 @kindex info functions
10112 @item info functions
10113 Print the names and data types of all defined functions.
10115 @item info functions @var{regexp}
10116 Print the names and data types of all defined functions
10117 whose names contain a match for regular expression @var{regexp}.
10118 Thus, @samp{info fun step} finds all functions whose names
10119 include @code{step}; @samp{info fun ^step} finds those whose names
10120 start with @code{step}. If a function name contains characters
10121 that conflict with the regular expression language (eg.
10122 @samp{operator*()}), they may be quoted with a backslash.
10124 @kindex info variables
10125 @item info variables
10126 Print the names and data types of all variables that are declared
10127 outside of functions (i.e.@: excluding local variables).
10129 @item info variables @var{regexp}
10130 Print the names and data types of all variables (except for local
10131 variables) whose names contain a match for regular expression
10134 @kindex info classes
10135 @cindex Objective-C, classes and selectors
10137 @itemx info classes @var{regexp}
10138 Display all Objective-C classes in your program, or
10139 (with the @var{regexp} argument) all those matching a particular regular
10142 @kindex info selectors
10143 @item info selectors
10144 @itemx info selectors @var{regexp}
10145 Display all Objective-C selectors in your program, or
10146 (with the @var{regexp} argument) all those matching a particular regular
10150 This was never implemented.
10151 @kindex info methods
10153 @itemx info methods @var{regexp}
10154 The @code{info methods} command permits the user to examine all defined
10155 methods within C@t{++} program, or (with the @var{regexp} argument) a
10156 specific set of methods found in the various C@t{++} classes. Many
10157 C@t{++} classes provide a large number of methods. Thus, the output
10158 from the @code{ptype} command can be overwhelming and hard to use. The
10159 @code{info-methods} command filters the methods, printing only those
10160 which match the regular-expression @var{regexp}.
10163 @cindex reloading symbols
10164 Some systems allow individual object files that make up your program to
10165 be replaced without stopping and restarting your program. For example,
10166 in VxWorks you can simply recompile a defective object file and keep on
10167 running. If you are running on one of these systems, you can allow
10168 @value{GDBN} to reload the symbols for automatically relinked modules:
10171 @kindex set symbol-reloading
10172 @item set symbol-reloading on
10173 Replace symbol definitions for the corresponding source file when an
10174 object file with a particular name is seen again.
10176 @item set symbol-reloading off
10177 Do not replace symbol definitions when encountering object files of the
10178 same name more than once. This is the default state; if you are not
10179 running on a system that permits automatic relinking of modules, you
10180 should leave @code{symbol-reloading} off, since otherwise @value{GDBN}
10181 may discard symbols when linking large programs, that may contain
10182 several modules (from different directories or libraries) with the same
10185 @kindex show symbol-reloading
10186 @item show symbol-reloading
10187 Show the current @code{on} or @code{off} setting.
10190 @cindex opaque data types
10191 @kindex set opaque-type-resolution
10192 @item set opaque-type-resolution on
10193 Tell @value{GDBN} to resolve opaque types. An opaque type is a type
10194 declared as a pointer to a @code{struct}, @code{class}, or
10195 @code{union}---for example, @code{struct MyType *}---that is used in one
10196 source file although the full declaration of @code{struct MyType} is in
10197 another source file. The default is on.
10199 A change in the setting of this subcommand will not take effect until
10200 the next time symbols for a file are loaded.
10202 @item set opaque-type-resolution off
10203 Tell @value{GDBN} not to resolve opaque types. In this case, the type
10204 is printed as follows:
10206 @{<no data fields>@}
10209 @kindex show opaque-type-resolution
10210 @item show opaque-type-resolution
10211 Show whether opaque types are resolved or not.
10213 @kindex maint print symbols
10214 @cindex symbol dump
10215 @kindex maint print psymbols
10216 @cindex partial symbol dump
10217 @item maint print symbols @var{filename}
10218 @itemx maint print psymbols @var{filename}
10219 @itemx maint print msymbols @var{filename}
10220 Write a dump of debugging symbol data into the file @var{filename}.
10221 These commands are used to debug the @value{GDBN} symbol-reading code. Only
10222 symbols with debugging data are included. If you use @samp{maint print
10223 symbols}, @value{GDBN} includes all the symbols for which it has already
10224 collected full details: that is, @var{filename} reflects symbols for
10225 only those files whose symbols @value{GDBN} has read. You can use the
10226 command @code{info sources} to find out which files these are. If you
10227 use @samp{maint print psymbols} instead, the dump shows information about
10228 symbols that @value{GDBN} only knows partially---that is, symbols defined in
10229 files that @value{GDBN} has skimmed, but not yet read completely. Finally,
10230 @samp{maint print msymbols} dumps just the minimal symbol information
10231 required for each object file from which @value{GDBN} has read some symbols.
10232 @xref{Files, ,Commands to specify files}, for a discussion of how
10233 @value{GDBN} reads symbols (in the description of @code{symbol-file}).
10235 @kindex maint info symtabs
10236 @kindex maint info psymtabs
10237 @cindex listing @value{GDBN}'s internal symbol tables
10238 @cindex symbol tables, listing @value{GDBN}'s internal
10239 @cindex full symbol tables, listing @value{GDBN}'s internal
10240 @cindex partial symbol tables, listing @value{GDBN}'s internal
10241 @item maint info symtabs @r{[} @var{regexp} @r{]}
10242 @itemx maint info psymtabs @r{[} @var{regexp} @r{]}
10244 List the @code{struct symtab} or @code{struct partial_symtab}
10245 structures whose names match @var{regexp}. If @var{regexp} is not
10246 given, list them all. The output includes expressions which you can
10247 copy into a @value{GDBN} debugging this one to examine a particular
10248 structure in more detail. For example:
10251 (@value{GDBP}) maint info psymtabs dwarf2read
10252 @{ objfile /home/gnu/build/gdb/gdb
10253 ((struct objfile *) 0x82e69d0)
10254 @{ psymtab /home/gnu/src/gdb/dwarf2read.c
10255 ((struct partial_symtab *) 0x8474b10)
10258 text addresses 0x814d3c8 -- 0x8158074
10259 globals (* (struct partial_symbol **) 0x8507a08 @@ 9)
10260 statics (* (struct partial_symbol **) 0x40e95b78 @@ 2882)
10261 dependencies (none)
10264 (@value{GDBP}) maint info symtabs
10268 We see that there is one partial symbol table whose filename contains
10269 the string @samp{dwarf2read}, belonging to the @samp{gdb} executable;
10270 and we see that @value{GDBN} has not read in any symtabs yet at all.
10271 If we set a breakpoint on a function, that will cause @value{GDBN} to
10272 read the symtab for the compilation unit containing that function:
10275 (@value{GDBP}) break dwarf2_psymtab_to_symtab
10276 Breakpoint 1 at 0x814e5da: file /home/gnu/src/gdb/dwarf2read.c,
10278 (@value{GDBP}) maint info symtabs
10279 @{ objfile /home/gnu/build/gdb/gdb
10280 ((struct objfile *) 0x82e69d0)
10281 @{ symtab /home/gnu/src/gdb/dwarf2read.c
10282 ((struct symtab *) 0x86c1f38)
10285 blockvector ((struct blockvector *) 0x86c1bd0) (primary)
10286 debugformat DWARF 2
10295 @chapter Altering Execution
10297 Once you think you have found an error in your program, you might want to
10298 find out for certain whether correcting the apparent error would lead to
10299 correct results in the rest of the run. You can find the answer by
10300 experiment, using the @value{GDBN} features for altering execution of the
10303 For example, you can store new values into variables or memory
10304 locations, give your program a signal, restart it at a different
10305 address, or even return prematurely from a function.
10308 * Assignment:: Assignment to variables
10309 * Jumping:: Continuing at a different address
10310 * Signaling:: Giving your program a signal
10311 * Returning:: Returning from a function
10312 * Calling:: Calling your program's functions
10313 * Patching:: Patching your program
10317 @section Assignment to variables
10320 @cindex setting variables
10321 To alter the value of a variable, evaluate an assignment expression.
10322 @xref{Expressions, ,Expressions}. For example,
10329 stores the value 4 into the variable @code{x}, and then prints the
10330 value of the assignment expression (which is 4).
10331 @xref{Languages, ,Using @value{GDBN} with Different Languages}, for more
10332 information on operators in supported languages.
10334 @kindex set variable
10335 @cindex variables, setting
10336 If you are not interested in seeing the value of the assignment, use the
10337 @code{set} command instead of the @code{print} command. @code{set} is
10338 really the same as @code{print} except that the expression's value is
10339 not printed and is not put in the value history (@pxref{Value History,
10340 ,Value history}). The expression is evaluated only for its effects.
10342 If the beginning of the argument string of the @code{set} command
10343 appears identical to a @code{set} subcommand, use the @code{set
10344 variable} command instead of just @code{set}. This command is identical
10345 to @code{set} except for its lack of subcommands. For example, if your
10346 program has a variable @code{width}, you get an error if you try to set
10347 a new value with just @samp{set width=13}, because @value{GDBN} has the
10348 command @code{set width}:
10351 (@value{GDBP}) whatis width
10353 (@value{GDBP}) p width
10355 (@value{GDBP}) set width=47
10356 Invalid syntax in expression.
10360 The invalid expression, of course, is @samp{=47}. In
10361 order to actually set the program's variable @code{width}, use
10364 (@value{GDBP}) set var width=47
10367 Because the @code{set} command has many subcommands that can conflict
10368 with the names of program variables, it is a good idea to use the
10369 @code{set variable} command instead of just @code{set}. For example, if
10370 your program has a variable @code{g}, you run into problems if you try
10371 to set a new value with just @samp{set g=4}, because @value{GDBN} has
10372 the command @code{set gnutarget}, abbreviated @code{set g}:
10376 (@value{GDBP}) whatis g
10380 (@value{GDBP}) set g=4
10384 The program being debugged has been started already.
10385 Start it from the beginning? (y or n) y
10386 Starting program: /home/smith/cc_progs/a.out
10387 "/home/smith/cc_progs/a.out": can't open to read symbols:
10388 Invalid bfd target.
10389 (@value{GDBP}) show g
10390 The current BFD target is "=4".
10395 The program variable @code{g} did not change, and you silently set the
10396 @code{gnutarget} to an invalid value. In order to set the variable
10400 (@value{GDBP}) set var g=4
10403 @value{GDBN} allows more implicit conversions in assignments than C; you can
10404 freely store an integer value into a pointer variable or vice versa,
10405 and you can convert any structure to any other structure that is the
10406 same length or shorter.
10407 @comment FIXME: how do structs align/pad in these conversions?
10408 @comment /doc@cygnus.com 18dec1990
10410 To store values into arbitrary places in memory, use the @samp{@{@dots{}@}}
10411 construct to generate a value of specified type at a specified address
10412 (@pxref{Expressions, ,Expressions}). For example, @code{@{int@}0x83040} refers
10413 to memory location @code{0x83040} as an integer (which implies a certain size
10414 and representation in memory), and
10417 set @{int@}0x83040 = 4
10421 stores the value 4 into that memory location.
10424 @section Continuing at a different address
10426 Ordinarily, when you continue your program, you do so at the place where
10427 it stopped, with the @code{continue} command. You can instead continue at
10428 an address of your own choosing, with the following commands:
10432 @item jump @var{linespec}
10433 Resume execution at line @var{linespec}. Execution stops again
10434 immediately if there is a breakpoint there. @xref{List, ,Printing
10435 source lines}, for a description of the different forms of
10436 @var{linespec}. It is common practice to use the @code{tbreak} command
10437 in conjunction with @code{jump}. @xref{Set Breaks, ,Setting
10440 The @code{jump} command does not change the current stack frame, or
10441 the stack pointer, or the contents of any memory location or any
10442 register other than the program counter. If line @var{linespec} is in
10443 a different function from the one currently executing, the results may
10444 be bizarre if the two functions expect different patterns of arguments or
10445 of local variables. For this reason, the @code{jump} command requests
10446 confirmation if the specified line is not in the function currently
10447 executing. However, even bizarre results are predictable if you are
10448 well acquainted with the machine-language code of your program.
10450 @item jump *@var{address}
10451 Resume execution at the instruction at address @var{address}.
10454 @c Doesn't work on HP-UX; have to set $pcoqh and $pcoqt.
10455 On many systems, you can get much the same effect as the @code{jump}
10456 command by storing a new value into the register @code{$pc}. The
10457 difference is that this does not start your program running; it only
10458 changes the address of where it @emph{will} run when you continue. For
10466 makes the next @code{continue} command or stepping command execute at
10467 address @code{0x485}, rather than at the address where your program stopped.
10468 @xref{Continuing and Stepping, ,Continuing and stepping}.
10470 The most common occasion to use the @code{jump} command is to back
10471 up---perhaps with more breakpoints set---over a portion of a program
10472 that has already executed, in order to examine its execution in more
10477 @section Giving your program a signal
10478 @cindex deliver a signal to a program
10482 @item signal @var{signal}
10483 Resume execution where your program stopped, but immediately give it the
10484 signal @var{signal}. @var{signal} can be the name or the number of a
10485 signal. For example, on many systems @code{signal 2} and @code{signal
10486 SIGINT} are both ways of sending an interrupt signal.
10488 Alternatively, if @var{signal} is zero, continue execution without
10489 giving a signal. This is useful when your program stopped on account of
10490 a signal and would ordinary see the signal when resumed with the
10491 @code{continue} command; @samp{signal 0} causes it to resume without a
10494 @code{signal} does not repeat when you press @key{RET} a second time
10495 after executing the command.
10499 Invoking the @code{signal} command is not the same as invoking the
10500 @code{kill} utility from the shell. Sending a signal with @code{kill}
10501 causes @value{GDBN} to decide what to do with the signal depending on
10502 the signal handling tables (@pxref{Signals}). The @code{signal} command
10503 passes the signal directly to your program.
10507 @section Returning from a function
10510 @cindex returning from a function
10513 @itemx return @var{expression}
10514 You can cancel execution of a function call with the @code{return}
10515 command. If you give an
10516 @var{expression} argument, its value is used as the function's return
10520 When you use @code{return}, @value{GDBN} discards the selected stack frame
10521 (and all frames within it). You can think of this as making the
10522 discarded frame return prematurely. If you wish to specify a value to
10523 be returned, give that value as the argument to @code{return}.
10525 This pops the selected stack frame (@pxref{Selection, ,Selecting a
10526 frame}), and any other frames inside of it, leaving its caller as the
10527 innermost remaining frame. That frame becomes selected. The
10528 specified value is stored in the registers used for returning values
10531 The @code{return} command does not resume execution; it leaves the
10532 program stopped in the state that would exist if the function had just
10533 returned. In contrast, the @code{finish} command (@pxref{Continuing
10534 and Stepping, ,Continuing and stepping}) resumes execution until the
10535 selected stack frame returns naturally.
10538 @section Calling program functions
10541 @cindex calling functions
10542 @cindex inferior functions, calling
10543 @item print @var{expr}
10544 Evaluate the expression @var{expr} and display the resuling value.
10545 @var{expr} may include calls to functions in the program being
10549 @item call @var{expr}
10550 Evaluate the expression @var{expr} without displaying @code{void}
10553 You can use this variant of the @code{print} command if you want to
10554 execute a function from your program that does not return anything
10555 (a.k.a.@: @dfn{a void function}), but without cluttering the output
10556 with @code{void} returned values that @value{GDBN} will otherwise
10557 print. If the result is not void, it is printed and saved in the
10561 It is possible for the function you call via the @code{print} or
10562 @code{call} command to generate a signal (e.g., if there's a bug in
10563 the function, or if you passed it incorrect arguments). What happens
10564 in that case is controlled by the @code{set unwindonsignal} command.
10567 @item set unwindonsignal
10568 @kindex set unwindonsignal
10569 @cindex unwind stack in called functions
10570 @cindex call dummy stack unwinding
10571 Set unwinding of the stack if a signal is received while in a function
10572 that @value{GDBN} called in the program being debugged. If set to on,
10573 @value{GDBN} unwinds the stack it created for the call and restores
10574 the context to what it was before the call. If set to off (the
10575 default), @value{GDBN} stops in the frame where the signal was
10578 @item show unwindonsignal
10579 @kindex show unwindonsignal
10580 Show the current setting of stack unwinding in the functions called by
10584 @cindex weak alias functions
10585 Sometimes, a function you wish to call is actually a @dfn{weak alias}
10586 for another function. In such case, @value{GDBN} might not pick up
10587 the type information, including the types of the function arguments,
10588 which causes @value{GDBN} to call the inferior function incorrectly.
10589 As a result, the called function will function erroneously and may
10590 even crash. A solution to that is to use the name of the aliased
10594 @section Patching programs
10596 @cindex patching binaries
10597 @cindex writing into executables
10598 @cindex writing into corefiles
10600 By default, @value{GDBN} opens the file containing your program's
10601 executable code (or the corefile) read-only. This prevents accidental
10602 alterations to machine code; but it also prevents you from intentionally
10603 patching your program's binary.
10605 If you'd like to be able to patch the binary, you can specify that
10606 explicitly with the @code{set write} command. For example, you might
10607 want to turn on internal debugging flags, or even to make emergency
10613 @itemx set write off
10614 If you specify @samp{set write on}, @value{GDBN} opens executable and
10615 core files for both reading and writing; if you specify @samp{set write
10616 off} (the default), @value{GDBN} opens them read-only.
10618 If you have already loaded a file, you must load it again (using the
10619 @code{exec-file} or @code{core-file} command) after changing @code{set
10620 write}, for your new setting to take effect.
10624 Display whether executable files and core files are opened for writing
10625 as well as reading.
10629 @chapter @value{GDBN} Files
10631 @value{GDBN} needs to know the file name of the program to be debugged,
10632 both in order to read its symbol table and in order to start your
10633 program. To debug a core dump of a previous run, you must also tell
10634 @value{GDBN} the name of the core dump file.
10637 * Files:: Commands to specify files
10638 * Separate Debug Files:: Debugging information in separate files
10639 * Symbol Errors:: Errors reading symbol files
10643 @section Commands to specify files
10645 @cindex symbol table
10646 @cindex core dump file
10648 You may want to specify executable and core dump file names. The usual
10649 way to do this is at start-up time, using the arguments to
10650 @value{GDBN}'s start-up commands (@pxref{Invocation, , Getting In and
10651 Out of @value{GDBN}}).
10653 Occasionally it is necessary to change to a different file during a
10654 @value{GDBN} session. Or you may run @value{GDBN} and forget to
10655 specify a file you want to use. Or you are debugging a remote target
10656 via @code{gdbserver} (@pxref{Server, file}). In these situations the
10657 @value{GDBN} commands to specify new files are useful.
10660 @cindex executable file
10662 @item file @var{filename}
10663 Use @var{filename} as the program to be debugged. It is read for its
10664 symbols and for the contents of pure memory. It is also the program
10665 executed when you use the @code{run} command. If you do not specify a
10666 directory and the file is not found in the @value{GDBN} working directory,
10667 @value{GDBN} uses the environment variable @code{PATH} as a list of
10668 directories to search, just as the shell does when looking for a program
10669 to run. You can change the value of this variable, for both @value{GDBN}
10670 and your program, using the @code{path} command.
10672 On systems with memory-mapped files, an auxiliary file named
10673 @file{@var{filename}.syms} may hold symbol table information for
10674 @var{filename}. If so, @value{GDBN} maps in the symbol table from
10675 @file{@var{filename}.syms}, starting up more quickly. See the
10676 descriptions of the file options @samp{-mapped} and @samp{-readnow}
10677 (available on the command line, see @ref{File Options, , -readnow},
10678 and with the commands @code{file}, @code{symbol-file}, or
10679 @code{add-symbol-file}, described below), for more information.
10681 @cindex unlinked object files
10682 @cindex patching object files
10683 You can load unlinked object @file{.o} files into @value{GDBN} using
10684 the @code{file} command. You will not be able to ``run'' an object
10685 file, but you can disassemble functions and inspect variables. Also,
10686 if the underlying BFD functionality supports it, you could use
10687 @kbd{gdb -write} to patch object files using this technique. Note
10688 that @value{GDBN} can neither interpret nor modify relocations in this
10689 case, so branches and some initialized variables will appear to go to
10690 the wrong place. But this feature is still handy from time to time.
10693 @code{file} with no argument makes @value{GDBN} discard any information it
10694 has on both executable file and the symbol table.
10697 @item exec-file @r{[} @var{filename} @r{]}
10698 Specify that the program to be run (but not the symbol table) is found
10699 in @var{filename}. @value{GDBN} searches the environment variable @code{PATH}
10700 if necessary to locate your program. Omitting @var{filename} means to
10701 discard information on the executable file.
10703 @kindex symbol-file
10704 @item symbol-file @r{[} @var{filename} @r{]}
10705 Read symbol table information from file @var{filename}. @code{PATH} is
10706 searched when necessary. Use the @code{file} command to get both symbol
10707 table and program to run from the same file.
10709 @code{symbol-file} with no argument clears out @value{GDBN} information on your
10710 program's symbol table.
10712 The @code{symbol-file} command causes @value{GDBN} to forget the contents
10713 of its convenience variables, the value history, and all breakpoints and
10714 auto-display expressions. This is because they may contain pointers to
10715 the internal data recording symbols and data types, which are part of
10716 the old symbol table data being discarded inside @value{GDBN}.
10718 @code{symbol-file} does not repeat if you press @key{RET} again after
10721 When @value{GDBN} is configured for a particular environment, it
10722 understands debugging information in whatever format is the standard
10723 generated for that environment; you may use either a @sc{gnu} compiler, or
10724 other compilers that adhere to the local conventions.
10725 Best results are usually obtained from @sc{gnu} compilers; for example,
10726 using @code{@value{GCC}} you can generate debugging information for
10729 For most kinds of object files, with the exception of old SVR3 systems
10730 using COFF, the @code{symbol-file} command does not normally read the
10731 symbol table in full right away. Instead, it scans the symbol table
10732 quickly to find which source files and which symbols are present. The
10733 details are read later, one source file at a time, as they are needed.
10735 The purpose of this two-stage reading strategy is to make @value{GDBN}
10736 start up faster. For the most part, it is invisible except for
10737 occasional pauses while the symbol table details for a particular source
10738 file are being read. (The @code{set verbose} command can turn these
10739 pauses into messages if desired. @xref{Messages/Warnings, ,Optional
10740 warnings and messages}.)
10742 We have not implemented the two-stage strategy for COFF yet. When the
10743 symbol table is stored in COFF format, @code{symbol-file} reads the
10744 symbol table data in full right away. Note that ``stabs-in-COFF''
10745 still does the two-stage strategy, since the debug info is actually
10749 @cindex reading symbols immediately
10750 @cindex symbols, reading immediately
10752 @cindex memory-mapped symbol file
10753 @cindex saving symbol table
10754 @item symbol-file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]}
10755 @itemx file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]}
10756 You can override the @value{GDBN} two-stage strategy for reading symbol
10757 tables by using the @samp{-readnow} option with any of the commands that
10758 load symbol table information, if you want to be sure @value{GDBN} has the
10759 entire symbol table available.
10761 If memory-mapped files are available on your system through the
10762 @code{mmap} system call, you can use another option, @samp{-mapped}, to
10763 cause @value{GDBN} to write the symbols for your program into a reusable
10764 file. Future @value{GDBN} debugging sessions map in symbol information
10765 from this auxiliary symbol file (if the program has not changed), rather
10766 than spending time reading the symbol table from the executable
10767 program. Using the @samp{-mapped} option has the same effect as
10768 starting @value{GDBN} with the @samp{-mapped} command-line option.
10770 You can use both options together, to make sure the auxiliary symbol
10771 file has all the symbol information for your program.
10773 The auxiliary symbol file for a program called @var{myprog} is called
10774 @samp{@var{myprog}.syms}. Once this file exists (so long as it is newer
10775 than the corresponding executable), @value{GDBN} always attempts to use
10776 it when you debug @var{myprog}; no special options or commands are
10779 The @file{.syms} file is specific to the host machine where you run
10780 @value{GDBN}. It holds an exact image of the internal @value{GDBN}
10781 symbol table. It cannot be shared across multiple host platforms.
10783 @c FIXME: for now no mention of directories, since this seems to be in
10784 @c flux. 13mar1992 status is that in theory GDB would look either in
10785 @c current dir or in same dir as myprog; but issues like competing
10786 @c GDB's, or clutter in system dirs, mean that in practice right now
10787 @c only current dir is used. FFish says maybe a special GDB hierarchy
10788 @c (eg rooted in val of env var GDBSYMS) could exist for mappable symbol
10792 @item core-file @r{[}@var{filename}@r{]}
10794 Specify the whereabouts of a core dump file to be used as the ``contents
10795 of memory''. Traditionally, core files contain only some parts of the
10796 address space of the process that generated them; @value{GDBN} can access the
10797 executable file itself for other parts.
10799 @code{core-file} with no argument specifies that no core file is
10802 Note that the core file is ignored when your program is actually running
10803 under @value{GDBN}. So, if you have been running your program and you
10804 wish to debug a core file instead, you must kill the subprocess in which
10805 the program is running. To do this, use the @code{kill} command
10806 (@pxref{Kill Process, ,Killing the child process}).
10808 @kindex add-symbol-file
10809 @cindex dynamic linking
10810 @item add-symbol-file @var{filename} @var{address}
10811 @itemx add-symbol-file @var{filename} @var{address} @r{[} -readnow @r{]} @r{[} -mapped @r{]}
10812 @itemx add-symbol-file @var{filename} @r{-s}@var{section} @var{address} @dots{}
10813 The @code{add-symbol-file} command reads additional symbol table
10814 information from the file @var{filename}. You would use this command
10815 when @var{filename} has been dynamically loaded (by some other means)
10816 into the program that is running. @var{address} should be the memory
10817 address at which the file has been loaded; @value{GDBN} cannot figure
10818 this out for itself. You can additionally specify an arbitrary number
10819 of @samp{@r{-s}@var{section} @var{address}} pairs, to give an explicit
10820 section name and base address for that section. You can specify any
10821 @var{address} as an expression.
10823 The symbol table of the file @var{filename} is added to the symbol table
10824 originally read with the @code{symbol-file} command. You can use the
10825 @code{add-symbol-file} command any number of times; the new symbol data
10826 thus read keeps adding to the old. To discard all old symbol data
10827 instead, use the @code{symbol-file} command without any arguments.
10829 @cindex relocatable object files, reading symbols from
10830 @cindex object files, relocatable, reading symbols from
10831 @cindex reading symbols from relocatable object files
10832 @cindex symbols, reading from relocatable object files
10833 @cindex @file{.o} files, reading symbols from
10834 Although @var{filename} is typically a shared library file, an
10835 executable file, or some other object file which has been fully
10836 relocated for loading into a process, you can also load symbolic
10837 information from relocatable @file{.o} files, as long as:
10841 the file's symbolic information refers only to linker symbols defined in
10842 that file, not to symbols defined by other object files,
10844 every section the file's symbolic information refers to has actually
10845 been loaded into the inferior, as it appears in the file, and
10847 you can determine the address at which every section was loaded, and
10848 provide these to the @code{add-symbol-file} command.
10852 Some embedded operating systems, like Sun Chorus and VxWorks, can load
10853 relocatable files into an already running program; such systems
10854 typically make the requirements above easy to meet. However, it's
10855 important to recognize that many native systems use complex link
10856 procedures (@code{.linkonce} section factoring and C@t{++} constructor table
10857 assembly, for example) that make the requirements difficult to meet. In
10858 general, one cannot assume that using @code{add-symbol-file} to read a
10859 relocatable object file's symbolic information will have the same effect
10860 as linking the relocatable object file into the program in the normal
10863 @code{add-symbol-file} does not repeat if you press @key{RET} after using it.
10865 You can use the @samp{-mapped} and @samp{-readnow} options just as with
10866 the @code{symbol-file} command, to change how @value{GDBN} manages the symbol
10867 table information for @var{filename}.
10869 @kindex add-symbol-file-from-memory
10870 @cindex @code{syscall DSO}
10871 @cindex load symbols from memory
10872 @item add-symbol-file-from-memory @var{address}
10873 Load symbols from the given @var{address} in a dynamically loaded
10874 object file whose image is mapped directly into the inferior's memory.
10875 For example, the Linux kernel maps a @code{syscall DSO} into each
10876 process's address space; this DSO provides kernel-specific code for
10877 some system calls. The argument can be any expression whose
10878 evaluation yields the address of the file's shared object file header.
10879 For this command to work, you must have used @code{symbol-file} or
10880 @code{exec-file} commands in advance.
10882 @kindex add-shared-symbol-files
10884 @item add-shared-symbol-files @var{library-file}
10885 @itemx assf @var{library-file}
10886 The @code{add-shared-symbol-files} command can currently be used only
10887 in the Cygwin build of @value{GDBN} on MS-Windows OS, where it is an
10888 alias for the @code{dll-symbols} command (@pxref{Cygwin Native}).
10889 @value{GDBN} automatically looks for shared libraries, however if
10890 @value{GDBN} does not find yours, you can invoke
10891 @code{add-shared-symbol-files}. It takes one argument: the shared
10892 library's file name. @code{assf} is a shorthand alias for
10893 @code{add-shared-symbol-files}.
10896 @item section @var{section} @var{addr}
10897 The @code{section} command changes the base address of the named
10898 @var{section} of the exec file to @var{addr}. This can be used if the
10899 exec file does not contain section addresses, (such as in the
10900 @code{a.out} format), or when the addresses specified in the file
10901 itself are wrong. Each section must be changed separately. The
10902 @code{info files} command, described below, lists all the sections and
10906 @kindex info target
10909 @code{info files} and @code{info target} are synonymous; both print the
10910 current target (@pxref{Targets, ,Specifying a Debugging Target}),
10911 including the names of the executable and core dump files currently in
10912 use by @value{GDBN}, and the files from which symbols were loaded. The
10913 command @code{help target} lists all possible targets rather than
10916 @kindex maint info sections
10917 @item maint info sections
10918 Another command that can give you extra information about program sections
10919 is @code{maint info sections}. In addition to the section information
10920 displayed by @code{info files}, this command displays the flags and file
10921 offset of each section in the executable and core dump files. In addition,
10922 @code{maint info sections} provides the following command options (which
10923 may be arbitrarily combined):
10927 Display sections for all loaded object files, including shared libraries.
10928 @item @var{sections}
10929 Display info only for named @var{sections}.
10930 @item @var{section-flags}
10931 Display info only for sections for which @var{section-flags} are true.
10932 The section flags that @value{GDBN} currently knows about are:
10935 Section will have space allocated in the process when loaded.
10936 Set for all sections except those containing debug information.
10938 Section will be loaded from the file into the child process memory.
10939 Set for pre-initialized code and data, clear for @code{.bss} sections.
10941 Section needs to be relocated before loading.
10943 Section cannot be modified by the child process.
10945 Section contains executable code only.
10947 Section contains data only (no executable code).
10949 Section will reside in ROM.
10951 Section contains data for constructor/destructor lists.
10953 Section is not empty.
10955 An instruction to the linker to not output the section.
10956 @item COFF_SHARED_LIBRARY
10957 A notification to the linker that the section contains
10958 COFF shared library information.
10960 Section contains common symbols.
10963 @kindex set trust-readonly-sections
10964 @cindex read-only sections
10965 @item set trust-readonly-sections on
10966 Tell @value{GDBN} that readonly sections in your object file
10967 really are read-only (i.e.@: that their contents will not change).
10968 In that case, @value{GDBN} can fetch values from these sections
10969 out of the object file, rather than from the target program.
10970 For some targets (notably embedded ones), this can be a significant
10971 enhancement to debugging performance.
10973 The default is off.
10975 @item set trust-readonly-sections off
10976 Tell @value{GDBN} not to trust readonly sections. This means that
10977 the contents of the section might change while the program is running,
10978 and must therefore be fetched from the target when needed.
10980 @item show trust-readonly-sections
10981 Show the current setting of trusting readonly sections.
10984 All file-specifying commands allow both absolute and relative file names
10985 as arguments. @value{GDBN} always converts the file name to an absolute file
10986 name and remembers it that way.
10988 @cindex shared libraries
10989 @value{GDBN} supports GNU/Linux, MS-Windows, HP-UX, SunOS, SVr4, Irix,
10990 and IBM RS/6000 AIX shared libraries.
10992 @value{GDBN} automatically loads symbol definitions from shared libraries
10993 when you use the @code{run} command, or when you examine a core file.
10994 (Before you issue the @code{run} command, @value{GDBN} does not understand
10995 references to a function in a shared library, however---unless you are
10996 debugging a core file).
10998 On HP-UX, if the program loads a library explicitly, @value{GDBN}
10999 automatically loads the symbols at the time of the @code{shl_load} call.
11001 @c FIXME: some @value{GDBN} release may permit some refs to undef
11002 @c FIXME...symbols---eg in a break cmd---assuming they are from a shared
11003 @c FIXME...lib; check this from time to time when updating manual
11005 There are times, however, when you may wish to not automatically load
11006 symbol definitions from shared libraries, such as when they are
11007 particularly large or there are many of them.
11009 To control the automatic loading of shared library symbols, use the
11013 @kindex set auto-solib-add
11014 @item set auto-solib-add @var{mode}
11015 If @var{mode} is @code{on}, symbols from all shared object libraries
11016 will be loaded automatically when the inferior begins execution, you
11017 attach to an independently started inferior, or when the dynamic linker
11018 informs @value{GDBN} that a new library has been loaded. If @var{mode}
11019 is @code{off}, symbols must be loaded manually, using the
11020 @code{sharedlibrary} command. The default value is @code{on}.
11022 @cindex memory used for symbol tables
11023 If your program uses lots of shared libraries with debug info that
11024 takes large amounts of memory, you can decrease the @value{GDBN}
11025 memory footprint by preventing it from automatically loading the
11026 symbols from shared libraries. To that end, type @kbd{set
11027 auto-solib-add off} before running the inferior, then load each
11028 library whose debug symbols you do need with @kbd{sharedlibrary
11029 @var{regexp}}, where @var{regexp} is a regular expresion that matches
11030 the libraries whose symbols you want to be loaded.
11032 @kindex show auto-solib-add
11033 @item show auto-solib-add
11034 Display the current autoloading mode.
11037 @cindex load shared library
11038 To explicitly load shared library symbols, use the @code{sharedlibrary}
11042 @kindex info sharedlibrary
11045 @itemx info sharedlibrary
11046 Print the names of the shared libraries which are currently loaded.
11048 @kindex sharedlibrary
11050 @item sharedlibrary @var{regex}
11051 @itemx share @var{regex}
11052 Load shared object library symbols for files matching a
11053 Unix regular expression.
11054 As with files loaded automatically, it only loads shared libraries
11055 required by your program for a core file or after typing @code{run}. If
11056 @var{regex} is omitted all shared libraries required by your program are
11059 @item nosharedlibrary
11060 @kindex nosharedlibrary
11061 @cindex unload symbols from shared libraries
11062 Unload all shared object library symbols. This discards all symbols
11063 that have been loaded from all shared libraries. Symbols from shared
11064 libraries that were loaded by explicit user requests are not
11068 Sometimes you may wish that @value{GDBN} stops and gives you control
11069 when any of shared library events happen. Use the @code{set
11070 stop-on-solib-events} command for this:
11073 @item set stop-on-solib-events
11074 @kindex set stop-on-solib-events
11075 This command controls whether @value{GDBN} should give you control
11076 when the dynamic linker notifies it about some shared library event.
11077 The most common event of interest is loading or unloading of a new
11080 @item show stop-on-solib-events
11081 @kindex show stop-on-solib-events
11082 Show whether @value{GDBN} stops and gives you control when shared
11083 library events happen.
11086 Shared libraries are also supported in many cross or remote debugging
11087 configurations. A copy of the target's libraries need to be present on the
11088 host system; they need to be the same as the target libraries, although the
11089 copies on the target can be stripped as long as the copies on the host are
11092 @cindex where to look for shared libraries
11093 For remote debugging, you need to tell @value{GDBN} where the target
11094 libraries are, so that it can load the correct copies---otherwise, it
11095 may try to load the host's libraries. @value{GDBN} has two variables
11096 to specify the search directories for target libraries.
11099 @cindex prefix for shared library file names
11100 @kindex set solib-absolute-prefix
11101 @item set solib-absolute-prefix @var{path}
11102 If this variable is set, @var{path} will be used as a prefix for any
11103 absolute shared library paths; many runtime loaders store the absolute
11104 paths to the shared library in the target program's memory. If you use
11105 @samp{solib-absolute-prefix} to find shared libraries, they need to be laid
11106 out in the same way that they are on the target, with e.g.@: a
11107 @file{/usr/lib} hierarchy under @var{path}.
11109 @cindex default value of @samp{solib-absolute-prefix}
11110 @cindex @samp{--with-sysroot}
11111 You can set the default value of @samp{solib-absolute-prefix} by using the
11112 configure-time @samp{--with-sysroot} option.
11114 @kindex show solib-absolute-prefix
11115 @item show solib-absolute-prefix
11116 Display the current shared library prefix.
11118 @kindex set solib-search-path
11119 @item set solib-search-path @var{path}
11120 If this variable is set, @var{path} is a colon-separated list of directories
11121 to search for shared libraries. @samp{solib-search-path} is used after
11122 @samp{solib-absolute-prefix} fails to locate the library, or if the path to
11123 the library is relative instead of absolute. If you want to use
11124 @samp{solib-search-path} instead of @samp{solib-absolute-prefix}, be sure to
11125 set @samp{solib-absolute-prefix} to a nonexistant directory to prevent
11126 @value{GDBN} from finding your host's libraries.
11128 @kindex show solib-search-path
11129 @item show solib-search-path
11130 Display the current shared library search path.
11134 @node Separate Debug Files
11135 @section Debugging Information in Separate Files
11136 @cindex separate debugging information files
11137 @cindex debugging information in separate files
11138 @cindex @file{.debug} subdirectories
11139 @cindex debugging information directory, global
11140 @cindex global debugging information directory
11142 @value{GDBN} allows you to put a program's debugging information in a
11143 file separate from the executable itself, in a way that allows
11144 @value{GDBN} to find and load the debugging information automatically.
11145 Since debugging information can be very large --- sometimes larger
11146 than the executable code itself --- some systems distribute debugging
11147 information for their executables in separate files, which users can
11148 install only when they need to debug a problem.
11150 If an executable's debugging information has been extracted to a
11151 separate file, the executable should contain a @dfn{debug link} giving
11152 the name of the debugging information file (with no directory
11153 components), and a checksum of its contents. (The exact form of a
11154 debug link is described below.) If the full name of the directory
11155 containing the executable is @var{execdir}, and the executable has a
11156 debug link that specifies the name @var{debugfile}, then @value{GDBN}
11157 will automatically search for the debugging information file in three
11162 the directory containing the executable file (that is, it will look
11163 for a file named @file{@var{execdir}/@var{debugfile}},
11165 a subdirectory of that directory named @file{.debug} (that is, the
11166 file @file{@var{execdir}/.debug/@var{debugfile}}, and
11168 a subdirectory of the global debug file directory that includes the
11169 executable's full path, and the name from the link (that is, the file
11170 @file{@var{globaldebugdir}/@var{execdir}/@var{debugfile}}, where
11171 @var{globaldebugdir} is the global debug file directory, and
11172 @var{execdir} has been turned into a relative path).
11175 @value{GDBN} checks under each of these names for a debugging
11176 information file whose checksum matches that given in the link, and
11177 reads the debugging information from the first one it finds.
11179 So, for example, if you ask @value{GDBN} to debug @file{/usr/bin/ls},
11180 which has a link containing the name @file{ls.debug}, and the global
11181 debug directory is @file{/usr/lib/debug}, then @value{GDBN} will look
11182 for debug information in @file{/usr/bin/ls.debug},
11183 @file{/usr/bin/.debug/ls.debug}, and
11184 @file{/usr/lib/debug/usr/bin/ls.debug}.
11186 You can set the global debugging info directory's name, and view the
11187 name @value{GDBN} is currently using.
11191 @kindex set debug-file-directory
11192 @item set debug-file-directory @var{directory}
11193 Set the directory which @value{GDBN} searches for separate debugging
11194 information files to @var{directory}.
11196 @kindex show debug-file-directory
11197 @item show debug-file-directory
11198 Show the directory @value{GDBN} searches for separate debugging
11203 @cindex @code{.gnu_debuglink} sections
11204 @cindex debug links
11205 A debug link is a special section of the executable file named
11206 @code{.gnu_debuglink}. The section must contain:
11210 A filename, with any leading directory components removed, followed by
11213 zero to three bytes of padding, as needed to reach the next four-byte
11214 boundary within the section, and
11216 a four-byte CRC checksum, stored in the same endianness used for the
11217 executable file itself. The checksum is computed on the debugging
11218 information file's full contents by the function given below, passing
11219 zero as the @var{crc} argument.
11222 Any executable file format can carry a debug link, as long as it can
11223 contain a section named @code{.gnu_debuglink} with the contents
11226 The debugging information file itself should be an ordinary
11227 executable, containing a full set of linker symbols, sections, and
11228 debugging information. The sections of the debugging information file
11229 should have the same names, addresses and sizes as the original file,
11230 but they need not contain any data --- much like a @code{.bss} section
11231 in an ordinary executable.
11233 As of December 2002, there is no standard GNU utility to produce
11234 separated executable / debugging information file pairs. Ulrich
11235 Drepper's @file{elfutils} package, starting with version 0.53,
11236 contains a version of the @code{strip} command such that the command
11237 @kbd{strip foo -f foo.debug} removes the debugging information from
11238 the executable file @file{foo}, places it in the file
11239 @file{foo.debug}, and leaves behind a debug link in @file{foo}.
11241 Since there are many different ways to compute CRC's (different
11242 polynomials, reversals, byte ordering, etc.), the simplest way to
11243 describe the CRC used in @code{.gnu_debuglink} sections is to give the
11244 complete code for a function that computes it:
11246 @kindex gnu_debuglink_crc32
11249 gnu_debuglink_crc32 (unsigned long crc,
11250 unsigned char *buf, size_t len)
11252 static const unsigned long crc32_table[256] =
11254 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
11255 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
11256 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
11257 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
11258 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
11259 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
11260 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
11261 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
11262 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
11263 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
11264 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
11265 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
11266 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
11267 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
11268 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
11269 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
11270 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
11271 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
11272 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
11273 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
11274 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
11275 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
11276 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
11277 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
11278 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
11279 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
11280 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
11281 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
11282 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
11283 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
11284 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
11285 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
11286 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
11287 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
11288 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
11289 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
11290 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
11291 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
11292 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
11293 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
11294 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
11295 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
11296 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
11297 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
11298 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
11299 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
11300 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
11301 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
11302 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
11303 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
11304 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
11307 unsigned char *end;
11309 crc = ~crc & 0xffffffff;
11310 for (end = buf + len; buf < end; ++buf)
11311 crc = crc32_table[(crc ^ *buf) & 0xff] ^ (crc >> 8);
11312 return ~crc & 0xffffffff;
11317 @node Symbol Errors
11318 @section Errors reading symbol files
11320 While reading a symbol file, @value{GDBN} occasionally encounters problems,
11321 such as symbol types it does not recognize, or known bugs in compiler
11322 output. By default, @value{GDBN} does not notify you of such problems, since
11323 they are relatively common and primarily of interest to people
11324 debugging compilers. If you are interested in seeing information
11325 about ill-constructed symbol tables, you can either ask @value{GDBN} to print
11326 only one message about each such type of problem, no matter how many
11327 times the problem occurs; or you can ask @value{GDBN} to print more messages,
11328 to see how many times the problems occur, with the @code{set
11329 complaints} command (@pxref{Messages/Warnings, ,Optional warnings and
11332 The messages currently printed, and their meanings, include:
11335 @item inner block not inside outer block in @var{symbol}
11337 The symbol information shows where symbol scopes begin and end
11338 (such as at the start of a function or a block of statements). This
11339 error indicates that an inner scope block is not fully contained
11340 in its outer scope blocks.
11342 @value{GDBN} circumvents the problem by treating the inner block as if it had
11343 the same scope as the outer block. In the error message, @var{symbol}
11344 may be shown as ``@code{(don't know)}'' if the outer block is not a
11347 @item block at @var{address} out of order
11349 The symbol information for symbol scope blocks should occur in
11350 order of increasing addresses. This error indicates that it does not
11353 @value{GDBN} does not circumvent this problem, and has trouble
11354 locating symbols in the source file whose symbols it is reading. (You
11355 can often determine what source file is affected by specifying
11356 @code{set verbose on}. @xref{Messages/Warnings, ,Optional warnings and
11359 @item bad block start address patched
11361 The symbol information for a symbol scope block has a start address
11362 smaller than the address of the preceding source line. This is known
11363 to occur in the SunOS 4.1.1 (and earlier) C compiler.
11365 @value{GDBN} circumvents the problem by treating the symbol scope block as
11366 starting on the previous source line.
11368 @item bad string table offset in symbol @var{n}
11371 Symbol number @var{n} contains a pointer into the string table which is
11372 larger than the size of the string table.
11374 @value{GDBN} circumvents the problem by considering the symbol to have the
11375 name @code{foo}, which may cause other problems if many symbols end up
11378 @item unknown symbol type @code{0x@var{nn}}
11380 The symbol information contains new data types that @value{GDBN} does
11381 not yet know how to read. @code{0x@var{nn}} is the symbol type of the
11382 uncomprehended information, in hexadecimal.
11384 @value{GDBN} circumvents the error by ignoring this symbol information.
11385 This usually allows you to debug your program, though certain symbols
11386 are not accessible. If you encounter such a problem and feel like
11387 debugging it, you can debug @code{@value{GDBP}} with itself, breakpoint
11388 on @code{complain}, then go up to the function @code{read_dbx_symtab}
11389 and examine @code{*bufp} to see the symbol.
11391 @item stub type has NULL name
11393 @value{GDBN} could not find the full definition for a struct or class.
11395 @item const/volatile indicator missing (ok if using g++ v1.x), got@dots{}
11396 The symbol information for a C@t{++} member function is missing some
11397 information that recent versions of the compiler should have output for
11400 @item info mismatch between compiler and debugger
11402 @value{GDBN} could not parse a type specification output by the compiler.
11407 @chapter Specifying a Debugging Target
11409 @cindex debugging target
11410 A @dfn{target} is the execution environment occupied by your program.
11412 Often, @value{GDBN} runs in the same host environment as your program;
11413 in that case, the debugging target is specified as a side effect when
11414 you use the @code{file} or @code{core} commands. When you need more
11415 flexibility---for example, running @value{GDBN} on a physically separate
11416 host, or controlling a standalone system over a serial port or a
11417 realtime system over a TCP/IP connection---you can use the @code{target}
11418 command to specify one of the target types configured for @value{GDBN}
11419 (@pxref{Target Commands, ,Commands for managing targets}).
11421 @cindex target architecture
11422 It is possible to build @value{GDBN} for several different @dfn{target
11423 architectures}. When @value{GDBN} is built like that, you can choose
11424 one of the available architectures with the @kbd{set architecture}
11428 @kindex set architecture
11429 @kindex show architecture
11430 @item set architecture @var{arch}
11431 This command sets the current target architecture to @var{arch}. The
11432 value of @var{arch} can be @code{"auto"}, in addition to one of the
11433 supported architectures.
11435 @item show architecture
11436 Show the current target architecture.
11438 @item set processor
11440 @kindex set processor
11441 @kindex show processor
11442 These are alias commands for, respectively, @code{set architecture}
11443 and @code{show architecture}.
11447 * Active Targets:: Active targets
11448 * Target Commands:: Commands for managing targets
11449 * Byte Order:: Choosing target byte order
11450 * Remote:: Remote debugging
11451 * KOD:: Kernel Object Display
11455 @node Active Targets
11456 @section Active targets
11458 @cindex stacking targets
11459 @cindex active targets
11460 @cindex multiple targets
11462 There are three classes of targets: processes, core files, and
11463 executable files. @value{GDBN} can work concurrently on up to three
11464 active targets, one in each class. This allows you to (for example)
11465 start a process and inspect its activity without abandoning your work on
11468 For example, if you execute @samp{gdb a.out}, then the executable file
11469 @code{a.out} is the only active target. If you designate a core file as
11470 well---presumably from a prior run that crashed and coredumped---then
11471 @value{GDBN} has two active targets and uses them in tandem, looking
11472 first in the corefile target, then in the executable file, to satisfy
11473 requests for memory addresses. (Typically, these two classes of target
11474 are complementary, since core files contain only a program's
11475 read-write memory---variables and so on---plus machine status, while
11476 executable files contain only the program text and initialized data.)
11478 When you type @code{run}, your executable file becomes an active process
11479 target as well. When a process target is active, all @value{GDBN}
11480 commands requesting memory addresses refer to that target; addresses in
11481 an active core file or executable file target are obscured while the
11482 process target is active.
11484 Use the @code{core-file} and @code{exec-file} commands to select a new
11485 core file or executable target (@pxref{Files, ,Commands to specify
11486 files}). To specify as a target a process that is already running, use
11487 the @code{attach} command (@pxref{Attach, ,Debugging an already-running
11490 @node Target Commands
11491 @section Commands for managing targets
11494 @item target @var{type} @var{parameters}
11495 Connects the @value{GDBN} host environment to a target machine or
11496 process. A target is typically a protocol for talking to debugging
11497 facilities. You use the argument @var{type} to specify the type or
11498 protocol of the target machine.
11500 Further @var{parameters} are interpreted by the target protocol, but
11501 typically include things like device names or host names to connect
11502 with, process numbers, and baud rates.
11504 The @code{target} command does not repeat if you press @key{RET} again
11505 after executing the command.
11507 @kindex help target
11509 Displays the names of all targets available. To display targets
11510 currently selected, use either @code{info target} or @code{info files}
11511 (@pxref{Files, ,Commands to specify files}).
11513 @item help target @var{name}
11514 Describe a particular target, including any parameters necessary to
11517 @kindex set gnutarget
11518 @item set gnutarget @var{args}
11519 @value{GDBN} uses its own library BFD to read your files. @value{GDBN}
11520 knows whether it is reading an @dfn{executable},
11521 a @dfn{core}, or a @dfn{.o} file; however, you can specify the file format
11522 with the @code{set gnutarget} command. Unlike most @code{target} commands,
11523 with @code{gnutarget} the @code{target} refers to a program, not a machine.
11526 @emph{Warning:} To specify a file format with @code{set gnutarget},
11527 you must know the actual BFD name.
11531 @xref{Files, , Commands to specify files}.
11533 @kindex show gnutarget
11534 @item show gnutarget
11535 Use the @code{show gnutarget} command to display what file format
11536 @code{gnutarget} is set to read. If you have not set @code{gnutarget},
11537 @value{GDBN} will determine the file format for each file automatically,
11538 and @code{show gnutarget} displays @samp{The current BDF target is "auto"}.
11541 @cindex common targets
11542 Here are some common targets (available, or not, depending on the GDB
11547 @item target exec @var{program}
11548 @cindex executable file target
11549 An executable file. @samp{target exec @var{program}} is the same as
11550 @samp{exec-file @var{program}}.
11552 @item target core @var{filename}
11553 @cindex core dump file target
11554 A core dump file. @samp{target core @var{filename}} is the same as
11555 @samp{core-file @var{filename}}.
11557 @item target remote @var{dev}
11558 @cindex remote target
11559 Remote serial target in GDB-specific protocol. The argument @var{dev}
11560 specifies what serial device to use for the connection (e.g.
11561 @file{/dev/ttya}). @xref{Remote, ,Remote debugging}. @code{target remote}
11562 supports the @code{load} command. This is only useful if you have
11563 some other way of getting the stub to the target system, and you can put
11564 it somewhere in memory where it won't get clobbered by the download.
11567 @cindex built-in simulator target
11568 Builtin CPU simulator. @value{GDBN} includes simulators for most architectures.
11576 works; however, you cannot assume that a specific memory map, device
11577 drivers, or even basic I/O is available, although some simulators do
11578 provide these. For info about any processor-specific simulator details,
11579 see the appropriate section in @ref{Embedded Processors, ,Embedded
11584 Some configurations may include these targets as well:
11588 @item target nrom @var{dev}
11589 @cindex NetROM ROM emulator target
11590 NetROM ROM emulator. This target only supports downloading.
11594 Different targets are available on different configurations of @value{GDBN};
11595 your configuration may have more or fewer targets.
11597 Many remote targets require you to download the executable's code once
11598 you've successfully established a connection. You may wish to control
11599 various aspects of this process, such as the size of the data chunks
11600 used by @value{GDBN} to download program parts to the remote target.
11603 @kindex set download-write-size
11604 @item set download-write-size @var{size}
11605 Set the write size used when downloading a program. Only used when
11606 downloading a program onto a remote target. Specify zero or a
11607 negative value to disable blocked writes. The actual size of each
11608 transfer is also limited by the size of the target packet and the
11611 @kindex show download-write-size
11612 @item show download-write-size
11613 @kindex show download-write-size
11614 Show the current value of the write size.
11617 @kindex set hash@r{, for remote monitors}
11618 @cindex hash mark while downloading
11619 This command controls whether a hash mark @samp{#} is displayed while
11620 downloading a file to the remote monitor. If on, a hash mark is
11621 displayed after each S-record is successfully downloaded to the
11625 @kindex show hash@r{, for remote monitors}
11626 Show the current status of displaying the hash mark.
11628 @item set debug monitor
11629 @kindex set debug monitor
11630 @cindex display remote monitor communications
11631 Enable or disable display of communications messages between
11632 @value{GDBN} and the remote monitor.
11634 @item show debug monitor
11635 @kindex show debug monitor
11636 Show the current status of displaying communications between
11637 @value{GDBN} and the remote monitor.
11642 @kindex load @var{filename}
11643 @item load @var{filename}
11644 Depending on what remote debugging facilities are configured into
11645 @value{GDBN}, the @code{load} command may be available. Where it exists, it
11646 is meant to make @var{filename} (an executable) available for debugging
11647 on the remote system---by downloading, or dynamic linking, for example.
11648 @code{load} also records the @var{filename} symbol table in @value{GDBN}, like
11649 the @code{add-symbol-file} command.
11651 If your @value{GDBN} does not have a @code{load} command, attempting to
11652 execute it gets the error message ``@code{You can't do that when your
11653 target is @dots{}}''
11655 The file is loaded at whatever address is specified in the executable.
11656 For some object file formats, you can specify the load address when you
11657 link the program; for other formats, like a.out, the object file format
11658 specifies a fixed address.
11659 @c FIXME! This would be a good place for an xref to the GNU linker doc.
11661 @code{load} does not repeat if you press @key{RET} again after using it.
11665 @section Choosing target byte order
11667 @cindex choosing target byte order
11668 @cindex target byte order
11670 Some types of processors, such as the MIPS, PowerPC, and Renesas SH,
11671 offer the ability to run either big-endian or little-endian byte
11672 orders. Usually the executable or symbol will include a bit to
11673 designate the endian-ness, and you will not need to worry about
11674 which to use. However, you may still find it useful to adjust
11675 @value{GDBN}'s idea of processor endian-ness manually.
11679 @item set endian big
11680 Instruct @value{GDBN} to assume the target is big-endian.
11682 @item set endian little
11683 Instruct @value{GDBN} to assume the target is little-endian.
11685 @item set endian auto
11686 Instruct @value{GDBN} to use the byte order associated with the
11690 Display @value{GDBN}'s current idea of the target byte order.
11694 Note that these commands merely adjust interpretation of symbolic
11695 data on the host, and that they have absolutely no effect on the
11699 @section Remote debugging
11700 @cindex remote debugging
11702 If you are trying to debug a program running on a machine that cannot run
11703 @value{GDBN} in the usual way, it is often useful to use remote debugging.
11704 For example, you might use remote debugging on an operating system kernel,
11705 or on a small system which does not have a general purpose operating system
11706 powerful enough to run a full-featured debugger.
11708 Some configurations of @value{GDBN} have special serial or TCP/IP interfaces
11709 to make this work with particular debugging targets. In addition,
11710 @value{GDBN} comes with a generic serial protocol (specific to @value{GDBN},
11711 but not specific to any particular target system) which you can use if you
11712 write the remote stubs---the code that runs on the remote system to
11713 communicate with @value{GDBN}.
11715 Other remote targets may be available in your
11716 configuration of @value{GDBN}; use @code{help target} to list them.
11718 Once you've connected to the remote target, @value{GDBN} allows you to
11719 send arbitrary commands to the remote monitor:
11722 @item remote @var{command}
11723 @kindex remote@r{, a command}
11724 @cindex send command to remote monitor
11725 Send an arbitrary @var{command} string to the remote monitor.
11730 @section Kernel Object Display
11731 @cindex kernel object display
11734 Some targets support kernel object display. Using this facility,
11735 @value{GDBN} communicates specially with the underlying operating system
11736 and can display information about operating system-level objects such as
11737 mutexes and other synchronization objects. Exactly which objects can be
11738 displayed is determined on a per-OS basis.
11741 Use the @code{set os} command to set the operating system. This tells
11742 @value{GDBN} which kernel object display module to initialize:
11745 (@value{GDBP}) set os cisco
11749 The associated command @code{show os} displays the operating system
11750 set with the @code{set os} command; if no operating system has been
11751 set, @code{show os} will display an empty string @samp{""}.
11753 If @code{set os} succeeds, @value{GDBN} will display some information
11754 about the operating system, and will create a new @code{info} command
11755 which can be used to query the target. The @code{info} command is named
11756 after the operating system:
11760 (@value{GDBP}) info cisco
11761 List of Cisco Kernel Objects
11763 any Any and all objects
11766 Further subcommands can be used to query about particular objects known
11769 There is currently no way to determine whether a given operating
11770 system is supported other than to try setting it with @kbd{set os
11771 @var{name}}, where @var{name} is the name of the operating system you
11775 @node Remote Debugging
11776 @chapter Debugging remote programs
11779 * Connecting:: Connecting to a remote target
11780 * Server:: Using the gdbserver program
11781 * NetWare:: Using the gdbserve.nlm program
11782 * Remote configuration:: Remote configuration
11783 * remote stub:: Implementing a remote stub
11787 @section Connecting to a remote target
11789 On the @value{GDBN} host machine, you will need an unstripped copy of
11790 your program, since @value{GDBN} needs symobl and debugging information.
11791 Start up @value{GDBN} as usual, using the name of the local copy of your
11792 program as the first argument.
11794 @cindex serial line, @code{target remote}
11795 If you're using a serial line, you may want to give @value{GDBN} the
11796 @w{@samp{--baud}} option, or use the @code{set remotebaud} command
11797 (@pxref{Remote configuration, set remotebaud}) before the
11798 @code{target} command.
11800 After that, use @code{target remote} to establish communications with
11801 the target machine. Its argument specifies how to communicate---either
11802 via a devicename attached to a direct serial line, or a TCP or UDP port
11803 (possibly to a terminal server which in turn has a serial line to the
11804 target). For example, to use a serial line connected to the device
11805 named @file{/dev/ttyb}:
11808 target remote /dev/ttyb
11811 @cindex TCP port, @code{target remote}
11812 To use a TCP connection, use an argument of the form
11813 @code{@var{host}:@var{port}} or @code{tcp:@var{host}:@var{port}}.
11814 For example, to connect to port 2828 on a
11815 terminal server named @code{manyfarms}:
11818 target remote manyfarms:2828
11821 If your remote target is actually running on the same machine as
11822 your debugger session (e.g.@: a simulator of your target running on
11823 the same host), you can omit the hostname. For example, to connect
11824 to port 1234 on your local machine:
11827 target remote :1234
11831 Note that the colon is still required here.
11833 @cindex UDP port, @code{target remote}
11834 To use a UDP connection, use an argument of the form
11835 @code{udp:@var{host}:@var{port}}. For example, to connect to UDP port 2828
11836 on a terminal server named @code{manyfarms}:
11839 target remote udp:manyfarms:2828
11842 When using a UDP connection for remote debugging, you should keep in mind
11843 that the `U' stands for ``Unreliable''. UDP can silently drop packets on
11844 busy or unreliable networks, which will cause havoc with your debugging
11847 Now you can use all the usual commands to examine and change data and to
11848 step and continue the remote program.
11850 @cindex interrupting remote programs
11851 @cindex remote programs, interrupting
11852 Whenever @value{GDBN} is waiting for the remote program, if you type the
11853 interrupt character (often @key{C-C}), @value{GDBN} attempts to stop the
11854 program. This may or may not succeed, depending in part on the hardware
11855 and the serial drivers the remote system uses. If you type the
11856 interrupt character once again, @value{GDBN} displays this prompt:
11859 Interrupted while waiting for the program.
11860 Give up (and stop debugging it)? (y or n)
11863 If you type @kbd{y}, @value{GDBN} abandons the remote debugging session.
11864 (If you decide you want to try again later, you can use @samp{target
11865 remote} again to connect once more.) If you type @kbd{n}, @value{GDBN}
11866 goes back to waiting.
11869 @kindex detach (remote)
11871 When you have finished debugging the remote program, you can use the
11872 @code{detach} command to release it from @value{GDBN} control.
11873 Detaching from the target normally resumes its execution, but the results
11874 will depend on your particular remote stub. After the @code{detach}
11875 command, @value{GDBN} is free to connect to another target.
11879 The @code{disconnect} command behaves like @code{detach}, except that
11880 the target is generally not resumed. It will wait for @value{GDBN}
11881 (this instance or another one) to connect and continue debugging. After
11882 the @code{disconnect} command, @value{GDBN} is again free to connect to
11885 @cindex send command to remote monitor
11887 @item monitor @var{cmd}
11888 This command allows you to send commands directly to the remote
11893 @section Using the @code{gdbserver} program
11896 @cindex remote connection without stubs
11897 @code{gdbserver} is a control program for Unix-like systems, which
11898 allows you to connect your program with a remote @value{GDBN} via
11899 @code{target remote}---but without linking in the usual debugging stub.
11901 @code{gdbserver} is not a complete replacement for the debugging stubs,
11902 because it requires essentially the same operating-system facilities
11903 that @value{GDBN} itself does. In fact, a system that can run
11904 @code{gdbserver} to connect to a remote @value{GDBN} could also run
11905 @value{GDBN} locally! @code{gdbserver} is sometimes useful nevertheless,
11906 because it is a much smaller program than @value{GDBN} itself. It is
11907 also easier to port than all of @value{GDBN}, so you may be able to get
11908 started more quickly on a new system by using @code{gdbserver}.
11909 Finally, if you develop code for real-time systems, you may find that
11910 the tradeoffs involved in real-time operation make it more convenient to
11911 do as much development work as possible on another system, for example
11912 by cross-compiling. You can use @code{gdbserver} to make a similar
11913 choice for debugging.
11915 @value{GDBN} and @code{gdbserver} communicate via either a serial line
11916 or a TCP connection, using the standard @value{GDBN} remote serial
11920 @item On the target machine,
11921 you need to have a copy of the program you want to debug.
11922 @code{gdbserver} does not need your program's symbol table, so you can
11923 strip the program if necessary to save space. @value{GDBN} on the host
11924 system does all the symbol handling.
11926 To use the server, you must tell it how to communicate with @value{GDBN};
11927 the name of your program; and the arguments for your program. The usual
11931 target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ]
11934 @var{comm} is either a device name (to use a serial line) or a TCP
11935 hostname and portnumber. For example, to debug Emacs with the argument
11936 @samp{foo.txt} and communicate with @value{GDBN} over the serial port
11940 target> gdbserver /dev/com1 emacs foo.txt
11943 @code{gdbserver} waits passively for the host @value{GDBN} to communicate
11946 To use a TCP connection instead of a serial line:
11949 target> gdbserver host:2345 emacs foo.txt
11952 The only difference from the previous example is the first argument,
11953 specifying that you are communicating with the host @value{GDBN} via
11954 TCP. The @samp{host:2345} argument means that @code{gdbserver} is to
11955 expect a TCP connection from machine @samp{host} to local TCP port 2345.
11956 (Currently, the @samp{host} part is ignored.) You can choose any number
11957 you want for the port number as long as it does not conflict with any
11958 TCP ports already in use on the target system (for example, @code{23} is
11959 reserved for @code{telnet}).@footnote{If you choose a port number that
11960 conflicts with another service, @code{gdbserver} prints an error message
11961 and exits.} You must use the same port number with the host @value{GDBN}
11962 @code{target remote} command.
11964 On some targets, @code{gdbserver} can also attach to running programs.
11965 This is accomplished via the @code{--attach} argument. The syntax is:
11968 target> gdbserver @var{comm} --attach @var{pid}
11971 @var{pid} is the process ID of a currently running process. It isn't necessary
11972 to point @code{gdbserver} at a binary for the running process.
11975 @cindex attach to a program by name
11976 You can debug processes by name instead of process ID if your target has the
11977 @code{pidof} utility:
11980 target> gdbserver @var{comm} --attach `pidof @var{PROGRAM}`
11983 In case more than one copy of @var{PROGRAM} is running, or @var{PROGRAM}
11984 has multiple threads, most versions of @code{pidof} support the
11985 @code{-s} option to only return the first process ID.
11987 @item On the host machine,
11988 connect to your target (@pxref{Connecting,,Connecting to a remote target}).
11989 For TCP connections, you must start up @code{gdbserver} prior to using
11990 the @code{target remote} command. Otherwise you may get an error whose
11991 text depends on the host system, but which usually looks something like
11992 @samp{Connection refused}. You don't need to use the @code{load}
11993 command in @value{GDBN} when using @code{gdbserver}, since the program is
11994 already on the target. However, if you want to load the symbols (as
11995 you normally would), do that with the @code{file} command, and issue
11996 it @emph{before} connecting to the server; otherwise, you will get an
11997 error message saying @code{"Program is already running"}, since the
11998 program is considered running after the connection.
12003 @section Using the @code{gdbserve.nlm} program
12005 @kindex gdbserve.nlm
12006 @code{gdbserve.nlm} is a control program for NetWare systems, which
12007 allows you to connect your program with a remote @value{GDBN} via
12008 @code{target remote}.
12010 @value{GDBN} and @code{gdbserve.nlm} communicate via a serial line,
12011 using the standard @value{GDBN} remote serial protocol.
12014 @item On the target machine,
12015 you need to have a copy of the program you want to debug.
12016 @code{gdbserve.nlm} does not need your program's symbol table, so you
12017 can strip the program if necessary to save space. @value{GDBN} on the
12018 host system does all the symbol handling.
12020 To use the server, you must tell it how to communicate with
12021 @value{GDBN}; the name of your program; and the arguments for your
12022 program. The syntax is:
12025 load gdbserve [ BOARD=@var{board} ] [ PORT=@var{port} ]
12026 [ BAUD=@var{baud} ] @var{program} [ @var{args} @dots{} ]
12029 @var{board} and @var{port} specify the serial line; @var{baud} specifies
12030 the baud rate used by the connection. @var{port} and @var{node} default
12031 to 0, @var{baud} defaults to 9600@dmn{bps}.
12033 For example, to debug Emacs with the argument @samp{foo.txt}and
12034 communicate with @value{GDBN} over serial port number 2 or board 1
12035 using a 19200@dmn{bps} connection:
12038 load gdbserve BOARD=1 PORT=2 BAUD=19200 emacs foo.txt
12042 On the @value{GDBN} host machine, connect to your target (@pxref{Connecting,,
12043 Connecting to a remote target}).
12047 @node Remote configuration
12048 @section Remote configuration
12051 @kindex show remote
12052 This section documents the configuration options available when
12053 debugging remote programs. For the options related to the File I/O
12054 extensions of the remote protocol, see @ref{The system call,
12055 system-call-allowed}.
12058 @item set remoteaddresssize @var{bits}
12059 @cindex adress size for remote targets
12060 @cindex bits in remote address
12061 Set the maximum size of address in a memory packet to the specified
12062 number of bits. @value{GDBN} will mask off the address bits above
12063 that number, when it passes addresses to the remote target. The
12064 default value is the number of bits in the target's address.
12066 @item show remoteaddresssize
12067 Show the current value of remote address size in bits.
12069 @item set remotebaud @var{n}
12070 @cindex baud rate for remote targets
12071 Set the baud rate for the remote serial I/O to @var{n} baud. The
12072 value is used to set the speed of the serial port used for debugging
12075 @item show remotebaud
12076 Show the current speed of the remote connection.
12078 @item set remotebreak
12079 @cindex interrupt remote programs
12080 @cindex BREAK signal instead of Ctrl-C
12081 If set to on, @value{GDBN} sends a @code{BREAK} signal to the remote
12082 when you press the @key{Ctrl-C} key to interrupt the program running
12083 on the remote. If set to off, @value{GDBN} sends the @samp{Strl-C}
12084 character instead. The default is off, since most remote systems
12085 expect to see @samp{Ctrl-C} as the interrupt signal.
12087 @item show remotebreak
12088 Show whether @value{GDBN} sends @code{BREAK} or @samp{Ctrl-C} to
12089 interrupt the remote program.
12091 @item set remotedebug
12092 @cindex debug remote protocol
12093 @cindex remote protocol debugging
12094 @cindex display remote packets
12095 Control the debugging of the remote protocol. When enabled, each
12096 packet sent to or received from the remote target is displayed. The
12099 @item show remotedebug
12100 Show the current setting of the remote protocol debugging.
12102 @item set remotedevice @var{device}
12103 @cindex serial port name
12104 Set the name of the serial port through which to communicate to the
12105 remote target to @var{device}. This is the device used by
12106 @value{GDBN} to open the serial communications line to the remote
12107 target. There's no default, so you must set a valid port name for the
12108 remote serial communications to work. (Some varieties of the
12109 @code{target} command accept the port name as part of their
12112 @item show remotedevice
12113 Show the current name of the serial port.
12115 @item set remotelogbase @var{base}
12116 Set the base (a.k.a.@: radix) of logging serial protocol
12117 communications to @var{base}. Supported values of @var{base} are:
12118 @code{ascii}, @code{octal}, and @code{hex}. The default is
12121 @item show remotelogbase
12122 Show the current setting of the radix for logging remote serial
12125 @item set remotelogfile @var{file}
12126 @cindex record serial communications on file
12127 Record remote serial communications on the named @var{file}. The
12128 default is not to record at all.
12130 @item show remotelogfile.
12131 Show the current setting of the file name on which to record the
12132 serial communications.
12134 @item set remotetimeout @var{num}
12135 @cindex timeout for serial communications
12136 @cindex remote timeout
12137 Set the timeout limit to wait for the remote target to respond to
12138 @var{num} seconds. The default is 2 seconds.
12140 @item show remotetimeout
12141 Show the current number of seconds to wait for the remote target
12144 @cindex limit hardware breakpoints and watchpoints
12145 @cindex remote target, limit break- and watchpoints
12146 @anchor{set remote hardware-watchpoint-limit}
12147 @anchor{set remote hardware-breakpoint-limit}
12148 @item set remote hardware-watchpoint-limit @var{limit}
12149 @itemx set remote hardware-breakpoint-limit @var{limit}
12150 Restrict @value{GDBN} to using @var{limit} remote hardware breakpoint or
12151 watchpoints. A limit of -1, the default, is treated as unlimited.
12153 @item set remote fetch-register-packet
12154 @itemx set remote set-register-packet
12155 @itemx set remote P-packet
12156 @itemx set remote p-packet
12158 @cindex fetch registers from remote targets
12159 @cindex set registers in remote targets
12160 Determine whether @value{GDBN} can set and fetch registers from the
12161 remote target using the @samp{P} packets. The default depends on the
12162 remote stub's support of the @samp{P} packets (@value{GDBN} queries
12163 the stub when this packet is first required).
12165 @item show remote fetch-register-packet
12166 @itemx show remote set-register-packet
12167 @itemx show remote P-packet
12168 @itemx show remote p-packet
12169 Show the current setting of using the @samp{P} packets for setting and
12170 fetching registers from the remote target.
12172 @cindex binary downloads
12174 @item set remote binary-download-packet
12175 @itemx set remote X-packet
12176 Determine whether @value{GDBN} sends downloads in binary mode using
12177 the @samp{X} packets. The default is on.
12179 @item show remote binary-download-packet
12180 @itemx show remote X-packet
12181 Show the current setting of using the @samp{X} packets for binary
12184 @item set remote read-aux-vector-packet
12185 @cindex auxiliary vector of remote target
12186 @cindex @code{auxv}, and remote targets
12187 Set the use of the remote protocol's @samp{qPart:auxv:read} (target
12188 auxiliary vector read) request. This request is used to fetch the
12189 remote target's @dfn{auxiliary vector}, see @ref{OS Information,
12190 Auxiliary Vector}. The default setting depends on the remote stub's
12191 support of this request (@value{GDBN} queries the stub when this
12192 request is first required). @xref{General Query Packets, qPart}, for
12193 more information about this request.
12195 @item show remote read-aux-vector-packet
12196 Show the current setting of use of the @samp{qPart:auxv:read} request.
12198 @item set remote symbol-lookup-packet
12199 @cindex remote symbol lookup request
12200 Set the use of the remote protocol's @samp{qSymbol} (target symbol
12201 lookup) request. This request is used to communicate symbol
12202 information to the remote target, e.g., whenever a new shared library
12203 is loaded by the remote (@pxref{Files, shared libraries}). The
12204 default setting depends on the remote stub's support of this request
12205 (@value{GDBN} queries the stub when this request is first required).
12206 @xref{General Query Packets, qSymbol}, for more information about this
12209 @item show remote symbol-lookup-packet
12210 Show the current setting of use of the @samp{qSymbol} request.
12212 @item set remote verbose-resume-packet
12213 @cindex resume remote target
12214 @cindex signal thread, and remote targets
12215 @cindex single-step thread, and remote targets
12216 @cindex thread-specific operations on remote targets
12217 Set the use of the remote protocol's @samp{vCont} (descriptive resume)
12218 request. This request is used to resume specific threads in the
12219 remote target, and to single-step or signal them. The default setting
12220 depends on the remote stub's support of this request (@value{GDBN}
12221 queries the stub when this request is first required). This setting
12222 affects debugging of multithreaded programs: if @samp{vCont} cannot be
12223 used, @value{GDBN} might be unable to single-step a specific thread,
12224 especially under @code{set scheduler-locking off}; it is also
12225 impossible to pause a specific thread. @xref{Packets, vCont}, for
12228 @item show remote verbose-resume-packet
12229 Show the current setting of use of the @samp{vCont} request
12231 @item set remote software-breakpoint-packet
12232 @itemx set remote hardware-breakpoint-packet
12233 @itemx set remote write-watchpoint-packet
12234 @itemx set remote read-watchpoint-packet
12235 @itemx set remote access-watchpoint-packet
12236 @itemx set remote Z-packet
12238 @cindex remote hardware breakpoints and watchpoints
12239 These commands enable or disable the use of @samp{Z} packets for
12240 setting breakpoints and watchpoints in the remote target. The default
12241 depends on the remote stub's support of the @samp{Z} packets
12242 (@value{GDBN} queries the stub when each packet is first required).
12243 The command @code{set remote Z-packet}, kept for back-compatibility,
12244 turns on or off all the features that require the use of @samp{Z}
12247 @item show remote software-breakpoint-packet
12248 @itemx show remote hardware-breakpoint-packet
12249 @itemx show remote write-watchpoint-packet
12250 @itemx show remote read-watchpoint-packet
12251 @itemx show remote access-watchpoint-packet
12252 @itemx show remote Z-packet
12253 Show the current setting of @samp{Z} packets usage.
12255 @item set remote get-thread-local-storage-address
12256 @kindex set remote get-thread-local-storage-address
12257 @cindex thread local storage of remote targets
12258 This command enables or disables the use of the @samp{qGetTLSAddr}
12259 (Get Thread Local Storage Address) request packet. The default
12260 depends on whether the remote stub supports this request.
12261 @xref{General Query Packets, qGetTLSAddr}, for more details about this
12264 @item show remote get-thread-local-storage-address
12265 @kindex show remote get-thread-local-storage-address
12266 Show the current setting of @samp{qGetTLSAddr} packet usage.
12270 @section Implementing a remote stub
12272 @cindex debugging stub, example
12273 @cindex remote stub, example
12274 @cindex stub example, remote debugging
12275 The stub files provided with @value{GDBN} implement the target side of the
12276 communication protocol, and the @value{GDBN} side is implemented in the
12277 @value{GDBN} source file @file{remote.c}. Normally, you can simply allow
12278 these subroutines to communicate, and ignore the details. (If you're
12279 implementing your own stub file, you can still ignore the details: start
12280 with one of the existing stub files. @file{sparc-stub.c} is the best
12281 organized, and therefore the easiest to read.)
12283 @cindex remote serial debugging, overview
12284 To debug a program running on another machine (the debugging
12285 @dfn{target} machine), you must first arrange for all the usual
12286 prerequisites for the program to run by itself. For example, for a C
12291 A startup routine to set up the C runtime environment; these usually
12292 have a name like @file{crt0}. The startup routine may be supplied by
12293 your hardware supplier, or you may have to write your own.
12296 A C subroutine library to support your program's
12297 subroutine calls, notably managing input and output.
12300 A way of getting your program to the other machine---for example, a
12301 download program. These are often supplied by the hardware
12302 manufacturer, but you may have to write your own from hardware
12306 The next step is to arrange for your program to use a serial port to
12307 communicate with the machine where @value{GDBN} is running (the @dfn{host}
12308 machine). In general terms, the scheme looks like this:
12312 @value{GDBN} already understands how to use this protocol; when everything
12313 else is set up, you can simply use the @samp{target remote} command
12314 (@pxref{Targets,,Specifying a Debugging Target}).
12316 @item On the target,
12317 you must link with your program a few special-purpose subroutines that
12318 implement the @value{GDBN} remote serial protocol. The file containing these
12319 subroutines is called a @dfn{debugging stub}.
12321 On certain remote targets, you can use an auxiliary program
12322 @code{gdbserver} instead of linking a stub into your program.
12323 @xref{Server,,Using the @code{gdbserver} program}, for details.
12326 The debugging stub is specific to the architecture of the remote
12327 machine; for example, use @file{sparc-stub.c} to debug programs on
12330 @cindex remote serial stub list
12331 These working remote stubs are distributed with @value{GDBN}:
12336 @cindex @file{i386-stub.c}
12339 For Intel 386 and compatible architectures.
12342 @cindex @file{m68k-stub.c}
12343 @cindex Motorola 680x0
12345 For Motorola 680x0 architectures.
12348 @cindex @file{sh-stub.c}
12351 For Renesas SH architectures.
12354 @cindex @file{sparc-stub.c}
12356 For @sc{sparc} architectures.
12358 @item sparcl-stub.c
12359 @cindex @file{sparcl-stub.c}
12362 For Fujitsu @sc{sparclite} architectures.
12366 The @file{README} file in the @value{GDBN} distribution may list other
12367 recently added stubs.
12370 * Stub Contents:: What the stub can do for you
12371 * Bootstrapping:: What you must do for the stub
12372 * Debug Session:: Putting it all together
12375 @node Stub Contents
12376 @subsection What the stub can do for you
12378 @cindex remote serial stub
12379 The debugging stub for your architecture supplies these three
12383 @item set_debug_traps
12384 @findex set_debug_traps
12385 @cindex remote serial stub, initialization
12386 This routine arranges for @code{handle_exception} to run when your
12387 program stops. You must call this subroutine explicitly near the
12388 beginning of your program.
12390 @item handle_exception
12391 @findex handle_exception
12392 @cindex remote serial stub, main routine
12393 This is the central workhorse, but your program never calls it
12394 explicitly---the setup code arranges for @code{handle_exception} to
12395 run when a trap is triggered.
12397 @code{handle_exception} takes control when your program stops during
12398 execution (for example, on a breakpoint), and mediates communications
12399 with @value{GDBN} on the host machine. This is where the communications
12400 protocol is implemented; @code{handle_exception} acts as the @value{GDBN}
12401 representative on the target machine. It begins by sending summary
12402 information on the state of your program, then continues to execute,
12403 retrieving and transmitting any information @value{GDBN} needs, until you
12404 execute a @value{GDBN} command that makes your program resume; at that point,
12405 @code{handle_exception} returns control to your own code on the target
12409 @cindex @code{breakpoint} subroutine, remote
12410 Use this auxiliary subroutine to make your program contain a
12411 breakpoint. Depending on the particular situation, this may be the only
12412 way for @value{GDBN} to get control. For instance, if your target
12413 machine has some sort of interrupt button, you won't need to call this;
12414 pressing the interrupt button transfers control to
12415 @code{handle_exception}---in effect, to @value{GDBN}. On some machines,
12416 simply receiving characters on the serial port may also trigger a trap;
12417 again, in that situation, you don't need to call @code{breakpoint} from
12418 your own program---simply running @samp{target remote} from the host
12419 @value{GDBN} session gets control.
12421 Call @code{breakpoint} if none of these is true, or if you simply want
12422 to make certain your program stops at a predetermined point for the
12423 start of your debugging session.
12426 @node Bootstrapping
12427 @subsection What you must do for the stub
12429 @cindex remote stub, support routines
12430 The debugging stubs that come with @value{GDBN} are set up for a particular
12431 chip architecture, but they have no information about the rest of your
12432 debugging target machine.
12434 First of all you need to tell the stub how to communicate with the
12438 @item int getDebugChar()
12439 @findex getDebugChar
12440 Write this subroutine to read a single character from the serial port.
12441 It may be identical to @code{getchar} for your target system; a
12442 different name is used to allow you to distinguish the two if you wish.
12444 @item void putDebugChar(int)
12445 @findex putDebugChar
12446 Write this subroutine to write a single character to the serial port.
12447 It may be identical to @code{putchar} for your target system; a
12448 different name is used to allow you to distinguish the two if you wish.
12451 @cindex control C, and remote debugging
12452 @cindex interrupting remote targets
12453 If you want @value{GDBN} to be able to stop your program while it is
12454 running, you need to use an interrupt-driven serial driver, and arrange
12455 for it to stop when it receives a @code{^C} (@samp{\003}, the control-C
12456 character). That is the character which @value{GDBN} uses to tell the
12457 remote system to stop.
12459 Getting the debugging target to return the proper status to @value{GDBN}
12460 probably requires changes to the standard stub; one quick and dirty way
12461 is to just execute a breakpoint instruction (the ``dirty'' part is that
12462 @value{GDBN} reports a @code{SIGTRAP} instead of a @code{SIGINT}).
12464 Other routines you need to supply are:
12467 @item void exceptionHandler (int @var{exception_number}, void *@var{exception_address})
12468 @findex exceptionHandler
12469 Write this function to install @var{exception_address} in the exception
12470 handling tables. You need to do this because the stub does not have any
12471 way of knowing what the exception handling tables on your target system
12472 are like (for example, the processor's table might be in @sc{rom},
12473 containing entries which point to a table in @sc{ram}).
12474 @var{exception_number} is the exception number which should be changed;
12475 its meaning is architecture-dependent (for example, different numbers
12476 might represent divide by zero, misaligned access, etc). When this
12477 exception occurs, control should be transferred directly to
12478 @var{exception_address}, and the processor state (stack, registers,
12479 and so on) should be just as it is when a processor exception occurs. So if
12480 you want to use a jump instruction to reach @var{exception_address}, it
12481 should be a simple jump, not a jump to subroutine.
12483 For the 386, @var{exception_address} should be installed as an interrupt
12484 gate so that interrupts are masked while the handler runs. The gate
12485 should be at privilege level 0 (the most privileged level). The
12486 @sc{sparc} and 68k stubs are able to mask interrupts themselves without
12487 help from @code{exceptionHandler}.
12489 @item void flush_i_cache()
12490 @findex flush_i_cache
12491 On @sc{sparc} and @sc{sparclite} only, write this subroutine to flush the
12492 instruction cache, if any, on your target machine. If there is no
12493 instruction cache, this subroutine may be a no-op.
12495 On target machines that have instruction caches, @value{GDBN} requires this
12496 function to make certain that the state of your program is stable.
12500 You must also make sure this library routine is available:
12503 @item void *memset(void *, int, int)
12505 This is the standard library function @code{memset} that sets an area of
12506 memory to a known value. If you have one of the free versions of
12507 @code{libc.a}, @code{memset} can be found there; otherwise, you must
12508 either obtain it from your hardware manufacturer, or write your own.
12511 If you do not use the GNU C compiler, you may need other standard
12512 library subroutines as well; this varies from one stub to another,
12513 but in general the stubs are likely to use any of the common library
12514 subroutines which @code{@value{GCC}} generates as inline code.
12517 @node Debug Session
12518 @subsection Putting it all together
12520 @cindex remote serial debugging summary
12521 In summary, when your program is ready to debug, you must follow these
12526 Make sure you have defined the supporting low-level routines
12527 (@pxref{Bootstrapping,,What you must do for the stub}):
12529 @code{getDebugChar}, @code{putDebugChar},
12530 @code{flush_i_cache}, @code{memset}, @code{exceptionHandler}.
12534 Insert these lines near the top of your program:
12542 For the 680x0 stub only, you need to provide a variable called
12543 @code{exceptionHook}. Normally you just use:
12546 void (*exceptionHook)() = 0;
12550 but if before calling @code{set_debug_traps}, you set it to point to a
12551 function in your program, that function is called when
12552 @code{@value{GDBN}} continues after stopping on a trap (for example, bus
12553 error). The function indicated by @code{exceptionHook} is called with
12554 one parameter: an @code{int} which is the exception number.
12557 Compile and link together: your program, the @value{GDBN} debugging stub for
12558 your target architecture, and the supporting subroutines.
12561 Make sure you have a serial connection between your target machine and
12562 the @value{GDBN} host, and identify the serial port on the host.
12565 @c The "remote" target now provides a `load' command, so we should
12566 @c document that. FIXME.
12567 Download your program to your target machine (or get it there by
12568 whatever means the manufacturer provides), and start it.
12571 Start @value{GDBN} on the host, and connect to the target
12572 (@pxref{Connecting,,Connecting to a remote target}).
12576 @node Configurations
12577 @chapter Configuration-Specific Information
12579 While nearly all @value{GDBN} commands are available for all native and
12580 cross versions of the debugger, there are some exceptions. This chapter
12581 describes things that are only available in certain configurations.
12583 There are three major categories of configurations: native
12584 configurations, where the host and target are the same, embedded
12585 operating system configurations, which are usually the same for several
12586 different processor architectures, and bare embedded processors, which
12587 are quite different from each other.
12592 * Embedded Processors::
12599 This section describes details specific to particular native
12604 * BSD libkvm Interface:: Debugging BSD kernel memory images
12605 * SVR4 Process Information:: SVR4 process information
12606 * DJGPP Native:: Features specific to the DJGPP port
12607 * Cygwin Native:: Features specific to the Cygwin port
12608 * Hurd Native:: Features specific to @sc{gnu} Hurd
12609 * Neutrino:: Features specific to QNX Neutrino
12615 On HP-UX systems, if you refer to a function or variable name that
12616 begins with a dollar sign, @value{GDBN} searches for a user or system
12617 name first, before it searches for a convenience variable.
12620 @node BSD libkvm Interface
12621 @subsection BSD libkvm Interface
12624 @cindex kernel memory image
12625 @cindex kernel crash dump
12627 BSD-derived systems (FreeBSD/NetBSD/OpenBSD) have a kernel memory
12628 interface that provides a uniform interface for accessing kernel virtual
12629 memory images, including live systems and crash dumps. @value{GDBN}
12630 uses this interface to allow you to debug live kernels and kernel crash
12631 dumps on many native BSD configurations. This is implemented as a
12632 special @code{kvm} debugging target. For debugging a live system, load
12633 the currently running kernel into @value{GDBN} and connect to the
12637 (@value{GDBP}) @b{target kvm}
12640 For debugging crash dumps, provide the file name of the crash dump as an
12644 (@value{GDBP}) @b{target kvm /var/crash/bsd.0}
12647 Once connected to the @code{kvm} target, the following commands are
12653 Set current context from the @dfn{Process Control Block} (PCB) address.
12656 Set current context from proc address. This command isn't available on
12657 modern FreeBSD systems.
12660 @node SVR4 Process Information
12661 @subsection SVR4 process information
12663 @cindex examine process image
12664 @cindex process info via @file{/proc}
12666 Many versions of SVR4 and compatible systems provide a facility called
12667 @samp{/proc} that can be used to examine the image of a running
12668 process using file-system subroutines. If @value{GDBN} is configured
12669 for an operating system with this facility, the command @code{info
12670 proc} is available to report information about the process running
12671 your program, or about any process running on your system. @code{info
12672 proc} works only on SVR4 systems that include the @code{procfs} code.
12673 This includes, as of this writing, @sc{gnu}/Linux, OSF/1 (Digital
12674 Unix), Solaris, Irix, and Unixware, but not HP-UX, for example.
12680 @itemx info proc @var{process-id}
12681 Summarize available information about any running process. If a
12682 process ID is specified by @var{process-id}, display information about
12683 that process; otherwise display information about the program being
12684 debugged. The summary includes the debugged process ID, the command
12685 line used to invoke it, its current working directory, and its
12686 executable file's absolute file name.
12688 On some systems, @var{process-id} can be of the form
12689 @samp{[@var{pid}]/@var{tid}} which specifies a certain thread ID
12690 within a process. If the optional @var{pid} part is missing, it means
12691 a thread from the process being debugged (the leading @samp{/} still
12692 needs to be present, or else @value{GDBN} will interpret the number as
12693 a process ID rather than a thread ID).
12695 @item info proc mappings
12696 @cindex memory address space mappings
12697 Report the memory address space ranges accessible in the program, with
12698 information on whether the process has read, write, or execute access
12699 rights to each range. On @sc{gnu}/Linux systems, each memory range
12700 includes the object file which is mapped to that range, instead of the
12701 memory access rights to that range.
12703 @item info proc stat
12704 @itemx info proc status
12705 @cindex process detailed status information
12706 These subcommands are specific to @sc{gnu}/Linux systems. They show
12707 the process-related information, including the user ID and group ID;
12708 how many threads are there in the process; its virtual memory usage;
12709 the signals that are pending, blocked, and ignored; its TTY; its
12710 consumption of system and user time; its stack size; its @samp{nice}
12711 value; etc. For more information, see the @samp{proc} man page
12712 (type @kbd{man 5 proc} from your shell prompt).
12714 @item info proc all
12715 Show all the information about the process described under all of the
12716 above @code{info proc} subcommands.
12719 @comment These sub-options of 'info proc' were not included when
12720 @comment procfs.c was re-written. Keep their descriptions around
12721 @comment against the day when someone finds the time to put them back in.
12722 @kindex info proc times
12723 @item info proc times
12724 Starting time, user CPU time, and system CPU time for your program and
12727 @kindex info proc id
12729 Report on the process IDs related to your program: its own process ID,
12730 the ID of its parent, the process group ID, and the session ID.
12733 @item set procfs-trace
12734 @kindex set procfs-trace
12735 @cindex @code{procfs} API calls
12736 This command enables and disables tracing of @code{procfs} API calls.
12738 @item show procfs-trace
12739 @kindex show procfs-trace
12740 Show the current state of @code{procfs} API call tracing.
12742 @item set procfs-file @var{file}
12743 @kindex set procfs-file
12744 Tell @value{GDBN} to write @code{procfs} API trace to the named
12745 @var{file}. @value{GDBN} appends the trace info to the previous
12746 contents of the file. The default is to display the trace on the
12749 @item show procfs-file
12750 @kindex show procfs-file
12751 Show the file to which @code{procfs} API trace is written.
12753 @item proc-trace-entry
12754 @itemx proc-trace-exit
12755 @itemx proc-untrace-entry
12756 @itemx proc-untrace-exit
12757 @kindex proc-trace-entry
12758 @kindex proc-trace-exit
12759 @kindex proc-untrace-entry
12760 @kindex proc-untrace-exit
12761 These commands enable and disable tracing of entries into and exits
12762 from the @code{syscall} interface.
12765 @kindex info pidlist
12766 @cindex process list, QNX Neutrino
12767 For QNX Neutrino only, this command displays the list of all the
12768 processes and all the threads within each process.
12771 @kindex info meminfo
12772 @cindex mapinfo list, QNX Neutrino
12773 For QNX Neutrino only, this command displays the list of all mapinfos.
12777 @subsection Features for Debugging @sc{djgpp} Programs
12778 @cindex @sc{djgpp} debugging
12779 @cindex native @sc{djgpp} debugging
12780 @cindex MS-DOS-specific commands
12783 @sc{djgpp} is a port of the @sc{gnu} development tools to MS-DOS and
12784 MS-Windows. @sc{djgpp} programs are 32-bit protected-mode programs
12785 that use the @dfn{DPMI} (DOS Protected-Mode Interface) API to run on
12786 top of real-mode DOS systems and their emulations.
12788 @value{GDBN} supports native debugging of @sc{djgpp} programs, and
12789 defines a few commands specific to the @sc{djgpp} port. This
12790 subsection describes those commands.
12795 This is a prefix of @sc{djgpp}-specific commands which print
12796 information about the target system and important OS structures.
12799 @cindex MS-DOS system info
12800 @cindex free memory information (MS-DOS)
12801 @item info dos sysinfo
12802 This command displays assorted information about the underlying
12803 platform: the CPU type and features, the OS version and flavor, the
12804 DPMI version, and the available conventional and DPMI memory.
12809 @cindex segment descriptor tables
12810 @cindex descriptor tables display
12812 @itemx info dos ldt
12813 @itemx info dos idt
12814 These 3 commands display entries from, respectively, Global, Local,
12815 and Interrupt Descriptor Tables (GDT, LDT, and IDT). The descriptor
12816 tables are data structures which store a descriptor for each segment
12817 that is currently in use. The segment's selector is an index into a
12818 descriptor table; the table entry for that index holds the
12819 descriptor's base address and limit, and its attributes and access
12822 A typical @sc{djgpp} program uses 3 segments: a code segment, a data
12823 segment (used for both data and the stack), and a DOS segment (which
12824 allows access to DOS/BIOS data structures and absolute addresses in
12825 conventional memory). However, the DPMI host will usually define
12826 additional segments in order to support the DPMI environment.
12828 @cindex garbled pointers
12829 These commands allow to display entries from the descriptor tables.
12830 Without an argument, all entries from the specified table are
12831 displayed. An argument, which should be an integer expression, means
12832 display a single entry whose index is given by the argument. For
12833 example, here's a convenient way to display information about the
12834 debugged program's data segment:
12837 @exdent @code{(@value{GDBP}) info dos ldt $ds}
12838 @exdent @code{0x13f: base=0x11970000 limit=0x0009ffff 32-Bit Data (Read/Write, Exp-up)}
12842 This comes in handy when you want to see whether a pointer is outside
12843 the data segment's limit (i.e.@: @dfn{garbled}).
12845 @cindex page tables display (MS-DOS)
12847 @itemx info dos pte
12848 These two commands display entries from, respectively, the Page
12849 Directory and the Page Tables. Page Directories and Page Tables are
12850 data structures which control how virtual memory addresses are mapped
12851 into physical addresses. A Page Table includes an entry for every
12852 page of memory that is mapped into the program's address space; there
12853 may be several Page Tables, each one holding up to 4096 entries. A
12854 Page Directory has up to 4096 entries, one each for every Page Table
12855 that is currently in use.
12857 Without an argument, @kbd{info dos pde} displays the entire Page
12858 Directory, and @kbd{info dos pte} displays all the entries in all of
12859 the Page Tables. An argument, an integer expression, given to the
12860 @kbd{info dos pde} command means display only that entry from the Page
12861 Directory table. An argument given to the @kbd{info dos pte} command
12862 means display entries from a single Page Table, the one pointed to by
12863 the specified entry in the Page Directory.
12865 @cindex direct memory access (DMA) on MS-DOS
12866 These commands are useful when your program uses @dfn{DMA} (Direct
12867 Memory Access), which needs physical addresses to program the DMA
12870 These commands are supported only with some DPMI servers.
12872 @cindex physical address from linear address
12873 @item info dos address-pte @var{addr}
12874 This command displays the Page Table entry for a specified linear
12875 address. The argument @var{addr} is a linear address which should
12876 already have the appropriate segment's base address added to it,
12877 because this command accepts addresses which may belong to @emph{any}
12878 segment. For example, here's how to display the Page Table entry for
12879 the page where a variable @code{i} is stored:
12882 @exdent @code{(@value{GDBP}) info dos address-pte __djgpp_base_address + (char *)&i}
12883 @exdent @code{Page Table entry for address 0x11a00d30:}
12884 @exdent @code{Base=0x02698000 Dirty Acc. Not-Cached Write-Back Usr Read-Write +0xd30}
12888 This says that @code{i} is stored at offset @code{0xd30} from the page
12889 whose physical base address is @code{0x02698000}, and shows all the
12890 attributes of that page.
12892 Note that you must cast the addresses of variables to a @code{char *},
12893 since otherwise the value of @code{__djgpp_base_address}, the base
12894 address of all variables and functions in a @sc{djgpp} program, will
12895 be added using the rules of C pointer arithmetics: if @code{i} is
12896 declared an @code{int}, @value{GDBN} will add 4 times the value of
12897 @code{__djgpp_base_address} to the address of @code{i}.
12899 Here's another example, it displays the Page Table entry for the
12903 @exdent @code{(@value{GDBP}) info dos address-pte *((unsigned *)&_go32_info_block + 3)}
12904 @exdent @code{Page Table entry for address 0x29110:}
12905 @exdent @code{Base=0x00029000 Dirty Acc. Not-Cached Write-Back Usr Read-Write +0x110}
12909 (The @code{+ 3} offset is because the transfer buffer's address is the
12910 3rd member of the @code{_go32_info_block} structure.) The output
12911 clearly shows that this DPMI server maps the addresses in conventional
12912 memory 1:1, i.e.@: the physical (@code{0x00029000} + @code{0x110}) and
12913 linear (@code{0x29110}) addresses are identical.
12915 This command is supported only with some DPMI servers.
12918 @cindex DOS serial data link, remote debugging
12919 In addition to native debugging, the DJGPP port supports remote
12920 debugging via a serial data link. The following commands are specific
12921 to remote serial debugging in the DJGPP port of @value{GDBN}.
12924 @kindex set com1base
12925 @kindex set com1irq
12926 @kindex set com2base
12927 @kindex set com2irq
12928 @kindex set com3base
12929 @kindex set com3irq
12930 @kindex set com4base
12931 @kindex set com4irq
12932 @item set com1base @var{addr}
12933 This command sets the base I/O port address of the @file{COM1} serial
12936 @item set com1irq @var{irq}
12937 This command sets the @dfn{Interrupt Request} (@code{IRQ}) line to use
12938 for the @file{COM1} serial port.
12940 There are similar commands @samp{set com2base}, @samp{set com3irq},
12941 etc.@: for setting the port address and the @code{IRQ} lines for the
12944 @kindex show com1base
12945 @kindex show com1irq
12946 @kindex show com2base
12947 @kindex show com2irq
12948 @kindex show com3base
12949 @kindex show com3irq
12950 @kindex show com4base
12951 @kindex show com4irq
12952 The related commands @samp{show com1base}, @samp{show com1irq} etc.@:
12953 display the current settings of the base address and the @code{IRQ}
12954 lines used by the COM ports.
12957 @kindex info serial
12958 @cindex DOS serial port status
12959 This command prints the status of the 4 DOS serial ports. For each
12960 port, it prints whether it's active or not, its I/O base address and
12961 IRQ number, whether it uses a 16550-style FIFO, its baudrate, and the
12962 counts of various errors encountered so far.
12966 @node Cygwin Native
12967 @subsection Features for Debugging MS Windows PE executables
12968 @cindex MS Windows debugging
12969 @cindex native Cygwin debugging
12970 @cindex Cygwin-specific commands
12972 @value{GDBN} supports native debugging of MS Windows programs, including
12973 DLLs with and without symbolic debugging information. There are various
12974 additional Cygwin-specific commands, described in this subsection. The
12975 subsubsection @pxref{Non-debug DLL symbols} describes working with DLLs
12976 that have no debugging symbols.
12982 This is a prefix of MS Windows specific commands which print
12983 information about the target system and important OS structures.
12985 @item info w32 selector
12986 This command displays information returned by
12987 the Win32 API @code{GetThreadSelectorEntry} function.
12988 It takes an optional argument that is evaluated to
12989 a long value to give the information about this given selector.
12990 Without argument, this command displays information
12991 about the the six segment registers.
12995 This is a Cygwin specific alias of info shared.
12997 @kindex dll-symbols
12999 This command loads symbols from a dll similarly to
13000 add-sym command but without the need to specify a base address.
13002 @kindex set new-console
13003 @item set new-console @var{mode}
13004 If @var{mode} is @code{on} the debuggee will
13005 be started in a new console on next start.
13006 If @var{mode} is @code{off}i, the debuggee will
13007 be started in the same console as the debugger.
13009 @kindex show new-console
13010 @item show new-console
13011 Displays whether a new console is used
13012 when the debuggee is started.
13014 @kindex set new-group
13015 @item set new-group @var{mode}
13016 This boolean value controls whether the debuggee should
13017 start a new group or stay in the same group as the debugger.
13018 This affects the way the Windows OS handles
13021 @kindex show new-group
13022 @item show new-group
13023 Displays current value of new-group boolean.
13025 @kindex set debugevents
13026 @item set debugevents
13027 This boolean value adds debug output concerning events seen by the debugger.
13029 @kindex set debugexec
13030 @item set debugexec
13031 This boolean value adds debug output concerning execute events
13032 seen by the debugger.
13034 @kindex set debugexceptions
13035 @item set debugexceptions
13036 This boolean value adds debug ouptut concerning exception events
13037 seen by the debugger.
13039 @kindex set debugmemory
13040 @item set debugmemory
13041 This boolean value adds debug ouptut concerning memory events
13042 seen by the debugger.
13046 This boolean values specifies whether the debuggee is called
13047 via a shell or directly (default value is on).
13051 Displays if the debuggee will be started with a shell.
13056 * Non-debug DLL symbols:: Support for DLLs without debugging symbols
13059 @node Non-debug DLL symbols
13060 @subsubsection Support for DLLs without debugging symbols
13061 @cindex DLLs with no debugging symbols
13062 @cindex Minimal symbols and DLLs
13064 Very often on windows, some of the DLLs that your program relies on do
13065 not include symbolic debugging information (for example,
13066 @file{kernel32.dll}). When @value{GDBN} doesn't recognize any debugging
13067 symbols in a DLL, it relies on the minimal amount of symbolic
13068 information contained in the DLL's export table. This subsubsection
13069 describes working with such symbols, known internally to @value{GDBN} as
13070 ``minimal symbols''.
13072 Note that before the debugged program has started execution, no DLLs
13073 will have been loaded. The easiest way around this problem is simply to
13074 start the program --- either by setting a breakpoint or letting the
13075 program run once to completion. It is also possible to force
13076 @value{GDBN} to load a particular DLL before starting the executable ---
13077 see the shared library information in @pxref{Files} or the
13078 @code{dll-symbols} command in @pxref{Cygwin Native}. Currently,
13079 explicitly loading symbols from a DLL with no debugging information will
13080 cause the symbol names to be duplicated in @value{GDBN}'s lookup table,
13081 which may adversely affect symbol lookup performance.
13083 @subsubsection DLL name prefixes
13085 In keeping with the naming conventions used by the Microsoft debugging
13086 tools, DLL export symbols are made available with a prefix based on the
13087 DLL name, for instance @code{KERNEL32!CreateFileA}. The plain name is
13088 also entered into the symbol table, so @code{CreateFileA} is often
13089 sufficient. In some cases there will be name clashes within a program
13090 (particularly if the executable itself includes full debugging symbols)
13091 necessitating the use of the fully qualified name when referring to the
13092 contents of the DLL. Use single-quotes around the name to avoid the
13093 exclamation mark (``!'') being interpreted as a language operator.
13095 Note that the internal name of the DLL may be all upper-case, even
13096 though the file name of the DLL is lower-case, or vice-versa. Since
13097 symbols within @value{GDBN} are @emph{case-sensitive} this may cause
13098 some confusion. If in doubt, try the @code{info functions} and
13099 @code{info variables} commands or even @code{maint print msymbols} (see
13100 @pxref{Symbols}). Here's an example:
13103 (@value{GDBP}) info function CreateFileA
13104 All functions matching regular expression "CreateFileA":
13106 Non-debugging symbols:
13107 0x77e885f4 CreateFileA
13108 0x77e885f4 KERNEL32!CreateFileA
13112 (@value{GDBP}) info function !
13113 All functions matching regular expression "!":
13115 Non-debugging symbols:
13116 0x6100114c cygwin1!__assert
13117 0x61004034 cygwin1!_dll_crt0@@0
13118 0x61004240 cygwin1!dll_crt0(per_process *)
13122 @subsubsection Working with minimal symbols
13124 Symbols extracted from a DLL's export table do not contain very much
13125 type information. All that @value{GDBN} can do is guess whether a symbol
13126 refers to a function or variable depending on the linker section that
13127 contains the symbol. Also note that the actual contents of the memory
13128 contained in a DLL are not available unless the program is running. This
13129 means that you cannot examine the contents of a variable or disassemble
13130 a function within a DLL without a running program.
13132 Variables are generally treated as pointers and dereferenced
13133 automatically. For this reason, it is often necessary to prefix a
13134 variable name with the address-of operator (``&'') and provide explicit
13135 type information in the command. Here's an example of the type of
13139 (@value{GDBP}) print 'cygwin1!__argv'
13144 (@value{GDBP}) x 'cygwin1!__argv'
13145 0x10021610: "\230y\""
13148 And two possible solutions:
13151 (@value{GDBP}) print ((char **)'cygwin1!__argv')[0]
13152 $2 = 0x22fd98 "/cygdrive/c/mydirectory/myprogram"
13156 (@value{GDBP}) x/2x &'cygwin1!__argv'
13157 0x610c0aa8 <cygwin1!__argv>: 0x10021608 0x00000000
13158 (@value{GDBP}) x/x 0x10021608
13159 0x10021608: 0x0022fd98
13160 (@value{GDBP}) x/s 0x0022fd98
13161 0x22fd98: "/cygdrive/c/mydirectory/myprogram"
13164 Setting a break point within a DLL is possible even before the program
13165 starts execution. However, under these circumstances, @value{GDBN} can't
13166 examine the initial instructions of the function in order to skip the
13167 function's frame set-up code. You can work around this by using ``*&''
13168 to set the breakpoint at a raw memory address:
13171 (@value{GDBP}) break *&'python22!PyOS_Readline'
13172 Breakpoint 1 at 0x1e04eff0
13175 The author of these extensions is not entirely convinced that setting a
13176 break point within a shared DLL like @file{kernel32.dll} is completely
13180 @subsection Commands specific to @sc{gnu} Hurd systems
13181 @cindex @sc{gnu} Hurd debugging
13183 This subsection describes @value{GDBN} commands specific to the
13184 @sc{gnu} Hurd native debugging.
13189 @kindex set signals@r{, Hurd command}
13190 @kindex set sigs@r{, Hurd command}
13191 This command toggles the state of inferior signal interception by
13192 @value{GDBN}. Mach exceptions, such as breakpoint traps, are not
13193 affected by this command. @code{sigs} is a shorthand alias for
13198 @kindex show signals@r{, Hurd command}
13199 @kindex show sigs@r{, Hurd command}
13200 Show the current state of intercepting inferior's signals.
13202 @item set signal-thread
13203 @itemx set sigthread
13204 @kindex set signal-thread
13205 @kindex set sigthread
13206 This command tells @value{GDBN} which thread is the @code{libc} signal
13207 thread. That thread is run when a signal is delivered to a running
13208 process. @code{set sigthread} is the shorthand alias of @code{set
13211 @item show signal-thread
13212 @itemx show sigthread
13213 @kindex show signal-thread
13214 @kindex show sigthread
13215 These two commands show which thread will run when the inferior is
13216 delivered a signal.
13219 @kindex set stopped@r{, Hurd command}
13220 This commands tells @value{GDBN} that the inferior process is stopped,
13221 as with the @code{SIGSTOP} signal. The stopped process can be
13222 continued by delivering a signal to it.
13225 @kindex show stopped@r{, Hurd command}
13226 This command shows whether @value{GDBN} thinks the debuggee is
13229 @item set exceptions
13230 @kindex set exceptions@r{, Hurd command}
13231 Use this command to turn off trapping of exceptions in the inferior.
13232 When exception trapping is off, neither breakpoints nor
13233 single-stepping will work. To restore the default, set exception
13236 @item show exceptions
13237 @kindex show exceptions@r{, Hurd command}
13238 Show the current state of trapping exceptions in the inferior.
13240 @item set task pause
13241 @kindex set task@r{, Hurd commands}
13242 @cindex task attributes (@sc{gnu} Hurd)
13243 @cindex pause current task (@sc{gnu} Hurd)
13244 This command toggles task suspension when @value{GDBN} has control.
13245 Setting it to on takes effect immediately, and the task is suspended
13246 whenever @value{GDBN} gets control. Setting it to off will take
13247 effect the next time the inferior is continued. If this option is set
13248 to off, you can use @code{set thread default pause on} or @code{set
13249 thread pause on} (see below) to pause individual threads.
13251 @item show task pause
13252 @kindex show task@r{, Hurd commands}
13253 Show the current state of task suspension.
13255 @item set task detach-suspend-count
13256 @cindex task suspend count
13257 @cindex detach from task, @sc{gnu} Hurd
13258 This command sets the suspend count the task will be left with when
13259 @value{GDBN} detaches from it.
13261 @item show task detach-suspend-count
13262 Show the suspend count the task will be left with when detaching.
13264 @item set task exception-port
13265 @itemx set task excp
13266 @cindex task exception port, @sc{gnu} Hurd
13267 This command sets the task exception port to which @value{GDBN} will
13268 forward exceptions. The argument should be the value of the @dfn{send
13269 rights} of the task. @code{set task excp} is a shorthand alias.
13271 @item set noninvasive
13272 @cindex noninvasive task options
13273 This command switches @value{GDBN} to a mode that is the least
13274 invasive as far as interfering with the inferior is concerned. This
13275 is the same as using @code{set task pause}, @code{set exceptions}, and
13276 @code{set signals} to values opposite to the defaults.
13278 @item info send-rights
13279 @itemx info receive-rights
13280 @itemx info port-rights
13281 @itemx info port-sets
13282 @itemx info dead-names
13285 @cindex send rights, @sc{gnu} Hurd
13286 @cindex receive rights, @sc{gnu} Hurd
13287 @cindex port rights, @sc{gnu} Hurd
13288 @cindex port sets, @sc{gnu} Hurd
13289 @cindex dead names, @sc{gnu} Hurd
13290 These commands display information about, respectively, send rights,
13291 receive rights, port rights, port sets, and dead names of a task.
13292 There are also shorthand aliases: @code{info ports} for @code{info
13293 port-rights} and @code{info psets} for @code{info port-sets}.
13295 @item set thread pause
13296 @kindex set thread@r{, Hurd command}
13297 @cindex thread properties, @sc{gnu} Hurd
13298 @cindex pause current thread (@sc{gnu} Hurd)
13299 This command toggles current thread suspension when @value{GDBN} has
13300 control. Setting it to on takes effect immediately, and the current
13301 thread is suspended whenever @value{GDBN} gets control. Setting it to
13302 off will take effect the next time the inferior is continued.
13303 Normally, this command has no effect, since when @value{GDBN} has
13304 control, the whole task is suspended. However, if you used @code{set
13305 task pause off} (see above), this command comes in handy to suspend
13306 only the current thread.
13308 @item show thread pause
13309 @kindex show thread@r{, Hurd command}
13310 This command shows the state of current thread suspension.
13312 @item set thread run
13313 This comamnd sets whether the current thread is allowed to run.
13315 @item show thread run
13316 Show whether the current thread is allowed to run.
13318 @item set thread detach-suspend-count
13319 @cindex thread suspend count, @sc{gnu} Hurd
13320 @cindex detach from thread, @sc{gnu} Hurd
13321 This command sets the suspend count @value{GDBN} will leave on a
13322 thread when detaching. This number is relative to the suspend count
13323 found by @value{GDBN} when it notices the thread; use @code{set thread
13324 takeover-suspend-count} to force it to an absolute value.
13326 @item show thread detach-suspend-count
13327 Show the suspend count @value{GDBN} will leave on the thread when
13330 @item set thread exception-port
13331 @itemx set thread excp
13332 Set the thread exception port to which to forward exceptions. This
13333 overrides the port set by @code{set task exception-port} (see above).
13334 @code{set thread excp} is the shorthand alias.
13336 @item set thread takeover-suspend-count
13337 Normally, @value{GDBN}'s thread suspend counts are relative to the
13338 value @value{GDBN} finds when it notices each thread. This command
13339 changes the suspend counts to be absolute instead.
13341 @item set thread default
13342 @itemx show thread default
13343 @cindex thread default settings, @sc{gnu} Hurd
13344 Each of the above @code{set thread} commands has a @code{set thread
13345 default} counterpart (e.g., @code{set thread default pause}, @code{set
13346 thread default exception-port}, etc.). The @code{thread default}
13347 variety of commands sets the default thread properties for all
13348 threads; you can then change the properties of individual threads with
13349 the non-default commands.
13354 @subsection QNX Neutrino
13355 @cindex QNX Neutrino
13357 @value{GDBN} provides the following commands specific to the QNX
13361 @item set debug nto-debug
13362 @kindex set debug nto-debug
13363 When set to on, enables debugging messages specific to the QNX
13366 @item show debug nto-debug
13367 @kindex show debug nto-debug
13368 Show the current state of QNX Neutrino messages.
13373 @section Embedded Operating Systems
13375 This section describes configurations involving the debugging of
13376 embedded operating systems that are available for several different
13380 * VxWorks:: Using @value{GDBN} with VxWorks
13383 @value{GDBN} includes the ability to debug programs running on
13384 various real-time operating systems.
13387 @subsection Using @value{GDBN} with VxWorks
13393 @kindex target vxworks
13394 @item target vxworks @var{machinename}
13395 A VxWorks system, attached via TCP/IP. The argument @var{machinename}
13396 is the target system's machine name or IP address.
13400 On VxWorks, @code{load} links @var{filename} dynamically on the
13401 current target system as well as adding its symbols in @value{GDBN}.
13403 @value{GDBN} enables developers to spawn and debug tasks running on networked
13404 VxWorks targets from a Unix host. Already-running tasks spawned from
13405 the VxWorks shell can also be debugged. @value{GDBN} uses code that runs on
13406 both the Unix host and on the VxWorks target. The program
13407 @code{@value{GDBP}} is installed and executed on the Unix host. (It may be
13408 installed with the name @code{vxgdb}, to distinguish it from a
13409 @value{GDBN} for debugging programs on the host itself.)
13412 @item VxWorks-timeout @var{args}
13413 @kindex vxworks-timeout
13414 All VxWorks-based targets now support the option @code{vxworks-timeout}.
13415 This option is set by the user, and @var{args} represents the number of
13416 seconds @value{GDBN} waits for responses to rpc's. You might use this if
13417 your VxWorks target is a slow software simulator or is on the far side
13418 of a thin network line.
13421 The following information on connecting to VxWorks was current when
13422 this manual was produced; newer releases of VxWorks may use revised
13425 @findex INCLUDE_RDB
13426 To use @value{GDBN} with VxWorks, you must rebuild your VxWorks kernel
13427 to include the remote debugging interface routines in the VxWorks
13428 library @file{rdb.a}. To do this, define @code{INCLUDE_RDB} in the
13429 VxWorks configuration file @file{configAll.h} and rebuild your VxWorks
13430 kernel. The resulting kernel contains @file{rdb.a}, and spawns the
13431 source debugging task @code{tRdbTask} when VxWorks is booted. For more
13432 information on configuring and remaking VxWorks, see the manufacturer's
13434 @c VxWorks, see the @cite{VxWorks Programmer's Guide}.
13436 Once you have included @file{rdb.a} in your VxWorks system image and set
13437 your Unix execution search path to find @value{GDBN}, you are ready to
13438 run @value{GDBN}. From your Unix host, run @code{@value{GDBP}} (or
13439 @code{vxgdb}, depending on your installation).
13441 @value{GDBN} comes up showing the prompt:
13448 * VxWorks Connection:: Connecting to VxWorks
13449 * VxWorks Download:: VxWorks download
13450 * VxWorks Attach:: Running tasks
13453 @node VxWorks Connection
13454 @subsubsection Connecting to VxWorks
13456 The @value{GDBN} command @code{target} lets you connect to a VxWorks target on the
13457 network. To connect to a target whose host name is ``@code{tt}'', type:
13460 (vxgdb) target vxworks tt
13464 @value{GDBN} displays messages like these:
13467 Attaching remote machine across net...
13472 @value{GDBN} then attempts to read the symbol tables of any object modules
13473 loaded into the VxWorks target since it was last booted. @value{GDBN} locates
13474 these files by searching the directories listed in the command search
13475 path (@pxref{Environment, ,Your program's environment}); if it fails
13476 to find an object file, it displays a message such as:
13479 prog.o: No such file or directory.
13482 When this happens, add the appropriate directory to the search path with
13483 the @value{GDBN} command @code{path}, and execute the @code{target}
13486 @node VxWorks Download
13487 @subsubsection VxWorks download
13489 @cindex download to VxWorks
13490 If you have connected to the VxWorks target and you want to debug an
13491 object that has not yet been loaded, you can use the @value{GDBN}
13492 @code{load} command to download a file from Unix to VxWorks
13493 incrementally. The object file given as an argument to the @code{load}
13494 command is actually opened twice: first by the VxWorks target in order
13495 to download the code, then by @value{GDBN} in order to read the symbol
13496 table. This can lead to problems if the current working directories on
13497 the two systems differ. If both systems have NFS mounted the same
13498 filesystems, you can avoid these problems by using absolute paths.
13499 Otherwise, it is simplest to set the working directory on both systems
13500 to the directory in which the object file resides, and then to reference
13501 the file by its name, without any path. For instance, a program
13502 @file{prog.o} may reside in @file{@var{vxpath}/vw/demo/rdb} in VxWorks
13503 and in @file{@var{hostpath}/vw/demo/rdb} on the host. To load this
13504 program, type this on VxWorks:
13507 -> cd "@var{vxpath}/vw/demo/rdb"
13511 Then, in @value{GDBN}, type:
13514 (vxgdb) cd @var{hostpath}/vw/demo/rdb
13515 (vxgdb) load prog.o
13518 @value{GDBN} displays a response similar to this:
13521 Reading symbol data from wherever/vw/demo/rdb/prog.o... done.
13524 You can also use the @code{load} command to reload an object module
13525 after editing and recompiling the corresponding source file. Note that
13526 this makes @value{GDBN} delete all currently-defined breakpoints,
13527 auto-displays, and convenience variables, and to clear the value
13528 history. (This is necessary in order to preserve the integrity of
13529 debugger's data structures that reference the target system's symbol
13532 @node VxWorks Attach
13533 @subsubsection Running tasks
13535 @cindex running VxWorks tasks
13536 You can also attach to an existing task using the @code{attach} command as
13540 (vxgdb) attach @var{task}
13544 where @var{task} is the VxWorks hexadecimal task ID. The task can be running
13545 or suspended when you attach to it. Running tasks are suspended at
13546 the time of attachment.
13548 @node Embedded Processors
13549 @section Embedded Processors
13551 This section goes into details specific to particular embedded
13554 @cindex send command to simulator
13555 Whenever a specific embedded processor has a simulator, @value{GDBN}
13556 allows to send an arbitrary command to the simulator.
13559 @item sim @var{command}
13560 @kindex sim@r{, a command}
13561 Send an arbitrary @var{command} string to the simulator. Consult the
13562 documentation for the specific simulator in use for information about
13563 acceptable commands.
13569 * H8/300:: Renesas H8/300
13570 * H8/500:: Renesas H8/500
13571 * M32R/D:: Renesas M32R/D
13572 * M68K:: Motorola M68K
13573 * MIPS Embedded:: MIPS Embedded
13574 * OpenRISC 1000:: OpenRisc 1000
13575 * PA:: HP PA Embedded
13578 * Sparclet:: Tsqware Sparclet
13579 * Sparclite:: Fujitsu Sparclite
13580 * ST2000:: Tandem ST2000
13581 * Z8000:: Zilog Z8000
13584 * Super-H:: Renesas Super-H
13585 * WinCE:: Windows CE child processes
13594 @item target rdi @var{dev}
13595 ARM Angel monitor, via RDI library interface to ADP protocol. You may
13596 use this target to communicate with both boards running the Angel
13597 monitor, or with the EmbeddedICE JTAG debug device.
13600 @item target rdp @var{dev}
13605 @value{GDBN} provides the following ARM-specific commands:
13608 @item set arm disassembler
13610 This commands selects from a list of disassembly styles. The
13611 @code{"std"} style is the standard style.
13613 @item show arm disassembler
13615 Show the current disassembly style.
13617 @item set arm apcs32
13618 @cindex ARM 32-bit mode
13619 This command toggles ARM operation mode between 32-bit and 26-bit.
13621 @item show arm apcs32
13622 Display the current usage of the ARM 32-bit mode.
13624 @item set arm fpu @var{fputype}
13625 This command sets the ARM floating-point unit (FPU) type. The
13626 argument @var{fputype} can be one of these:
13630 Determine the FPU type by querying the OS ABI.
13632 Software FPU, with mixed-endian doubles on little-endian ARM
13635 GCC-compiled FPA co-processor.
13637 Software FPU with pure-endian doubles.
13643 Show the current type of the FPU.
13646 This command forces @value{GDBN} to use the specified ABI.
13649 Show the currently used ABI.
13651 @item set debug arm
13652 Toggle whether to display ARM-specific debugging messages from the ARM
13653 target support subsystem.
13655 @item show debug arm
13656 Show whether ARM-specific debugging messages are enabled.
13659 The following commands are available when an ARM target is debugged
13660 using the RDI interface:
13663 @item rdilogfile @r{[}@var{file}@r{]}
13665 @cindex ADP (Angel Debugger Protocol) logging
13666 Set the filename for the ADP (Angel Debugger Protocol) packet log.
13667 With an argument, sets the log file to the specified @var{file}. With
13668 no argument, show the current log file name. The default log file is
13671 @item rdilogenable @r{[}@var{arg}@r{]}
13672 @kindex rdilogenable
13673 Control logging of ADP packets. With an argument of 1 or @code{"yes"}
13674 enables logging, with an argument 0 or @code{"no"} disables it. With
13675 no arguments displays the current setting. When logging is enabled,
13676 ADP packets exchanged between @value{GDBN} and the RDI target device
13677 are logged to a file.
13679 @item set rdiromatzero
13680 @kindex set rdiromatzero
13681 @cindex ROM at zero address, RDI
13682 Tell @value{GDBN} whether the target has ROM at address 0. If on,
13683 vector catching is disabled, so that zero address can be used. If off
13684 (the default), vector catching is enabled. For this command to take
13685 effect, it needs to be invoked prior to the @code{target rdi} command.
13687 @item show rdiromatzero
13688 @kindex show rdiromatzero
13689 Show the current setting of ROM at zero address.
13691 @item set rdiheartbeat
13692 @kindex set rdiheartbeat
13693 @cindex RDI heartbeat
13694 Enable or disable RDI heartbeat packets. It is not recommended to
13695 turn on this option, since it confuses ARM and EPI JTAG interface, as
13696 well as the Angel monitor.
13698 @item show rdiheartbeat
13699 @kindex show rdiheartbeat
13700 Show the setting of RDI heartbeat packets.
13705 @subsection Renesas H8/300
13709 @kindex target hms@r{, with H8/300}
13710 @item target hms @var{dev}
13711 A Renesas SH, H8/300, or H8/500 board, attached via serial line to your host.
13712 Use special commands @code{device} and @code{speed} to control the serial
13713 line and the communications speed used.
13715 @kindex target e7000@r{, with H8/300}
13716 @item target e7000 @var{dev}
13717 E7000 emulator for Renesas H8 and SH.
13719 @kindex target sh3@r{, with H8/300}
13720 @kindex target sh3e@r{, with H8/300}
13721 @item target sh3 @var{dev}
13722 @itemx target sh3e @var{dev}
13723 Renesas SH-3 and SH-3E target systems.
13727 @cindex download to H8/300 or H8/500
13728 @cindex H8/300 or H8/500 download
13729 @cindex download to Renesas SH
13730 @cindex Renesas SH download
13731 When you select remote debugging to a Renesas SH, H8/300, or H8/500
13732 board, the @code{load} command downloads your program to the Renesas
13733 board and also opens it as the current executable target for
13734 @value{GDBN} on your host (like the @code{file} command).
13736 @value{GDBN} needs to know these things to talk to your
13737 Renesas SH, H8/300, or H8/500:
13741 that you want to use @samp{target hms}, the remote debugging interface
13742 for Renesas microprocessors, or @samp{target e7000}, the in-circuit
13743 emulator for the Renesas SH and the Renesas 300H. (@samp{target hms} is
13744 the default when @value{GDBN} is configured specifically for the Renesas SH,
13745 H8/300, or H8/500.)
13748 what serial device connects your host to your Renesas board (the first
13749 serial device available on your host is the default).
13752 what speed to use over the serial device.
13756 * Renesas Boards:: Connecting to Renesas boards.
13757 * Renesas ICE:: Using the E7000 In-Circuit Emulator.
13758 * Renesas Special:: Special @value{GDBN} commands for Renesas micros.
13761 @node Renesas Boards
13762 @subsubsection Connecting to Renesas boards
13764 @c only for Unix hosts
13766 @cindex serial device, Renesas micros
13767 Use the special @code{@value{GDBN}} command @samp{device @var{port}} if you
13768 need to explicitly set the serial device. The default @var{port} is the
13769 first available port on your host. This is only necessary on Unix
13770 hosts, where it is typically something like @file{/dev/ttya}.
13773 @cindex serial line speed, Renesas micros
13774 @code{@value{GDBN}} has another special command to set the communications
13775 speed: @samp{speed @var{bps}}. This command also is only used from Unix
13776 hosts; on DOS hosts, set the line speed as usual from outside @value{GDBN} with
13777 the DOS @code{mode} command (for instance,
13778 @w{@kbd{mode com2:9600,n,8,1,p}} for a 9600@dmn{bps} connection).
13780 The @samp{device} and @samp{speed} commands are available only when you
13781 use a Unix host to debug your Renesas microprocessor programs. If you
13783 @value{GDBN} depends on an auxiliary terminate-and-stay-resident program
13784 called @code{asynctsr} to communicate with the development board
13785 through a PC serial port. You must also use the DOS @code{mode} command
13786 to set up the serial port on the DOS side.
13788 The following sample session illustrates the steps needed to start a
13789 program under @value{GDBN} control on an H8/300. The example uses a
13790 sample H8/300 program called @file{t.x}. The procedure is the same for
13791 the Renesas SH and the H8/500.
13793 First hook up your development board. In this example, we use a
13794 board attached to serial port @code{COM2}; if you use a different serial
13795 port, substitute its name in the argument of the @code{mode} command.
13796 When you call @code{asynctsr}, the auxiliary comms program used by the
13797 debugger, you give it just the numeric part of the serial port's name;
13798 for example, @samp{asyncstr 2} below runs @code{asyncstr} on
13802 C:\H8300\TEST> asynctsr 2
13803 C:\H8300\TEST> mode com2:9600,n,8,1,p
13805 Resident portion of MODE loaded
13807 COM2: 9600, n, 8, 1, p
13812 @emph{Warning:} We have noticed a bug in PC-NFS that conflicts with
13813 @code{asynctsr}. If you also run PC-NFS on your DOS host, you may need to
13814 disable it, or even boot without it, to use @code{asynctsr} to control
13815 your development board.
13818 @kindex target hms@r{, and serial protocol}
13819 Now that serial communications are set up, and the development board is
13820 connected, you can start up @value{GDBN}. Call @code{@value{GDBN}} with
13821 the name of your program as the argument. @code{@value{GDBN}} prompts
13822 you, as usual, with the prompt @samp{(@value{GDBP})}. Use two special
13823 commands to begin your debugging session: @samp{target hms} to specify
13824 cross-debugging to the Renesas board, and the @code{load} command to
13825 download your program to the board. @code{load} displays the names of
13826 the program's sections, and a @samp{*} for each 2K of data downloaded.
13827 (If you want to refresh @value{GDBN} data on symbols or on the
13828 executable file without downloading, use the @value{GDBN} commands
13829 @code{file} or @code{symbol-file}. These commands, and @code{load}
13830 itself, are described in @ref{Files,,Commands to specify files}.)
13833 (eg-C:\H8300\TEST) @value{GDBP} t.x
13834 @value{GDBN} is free software and you are welcome to distribute copies
13835 of it under certain conditions; type "show copying" to see
13837 There is absolutely no warranty for @value{GDBN}; type "show warranty"
13839 @value{GDBN} @value{GDBVN}, Copyright 1992 Free Software Foundation, Inc...
13840 (@value{GDBP}) target hms
13841 Connected to remote H8/300 HMS system.
13842 (@value{GDBP}) load t.x
13843 .text : 0x8000 .. 0xabde ***********
13844 .data : 0xabde .. 0xad30 *
13845 .stack : 0xf000 .. 0xf014 *
13848 At this point, you're ready to run or debug your program. From here on,
13849 you can use all the usual @value{GDBN} commands. The @code{break} command
13850 sets breakpoints; the @code{run} command starts your program;
13851 @code{print} or @code{x} display data; the @code{continue} command
13852 resumes execution after stopping at a breakpoint. You can use the
13853 @code{help} command at any time to find out more about @value{GDBN} commands.
13855 Remember, however, that @emph{operating system} facilities aren't
13856 available on your development board; for example, if your program hangs,
13857 you can't send an interrupt---but you can press the @sc{reset} switch!
13859 Use the @sc{reset} button on the development board
13862 to interrupt your program (don't use @kbd{ctl-C} on the DOS host---it has
13863 no way to pass an interrupt signal to the development board); and
13866 to return to the @value{GDBN} command prompt after your program finishes
13867 normally. The communications protocol provides no other way for @value{GDBN}
13868 to detect program completion.
13871 In either case, @value{GDBN} sees the effect of a @sc{reset} on the
13872 development board as a ``normal exit'' of your program.
13875 @subsubsection Using the E7000 in-circuit emulator
13877 @kindex target e7000@r{, with Renesas ICE}
13878 You can use the E7000 in-circuit emulator to develop code for either the
13879 Renesas SH or the H8/300H. Use one of these forms of the @samp{target
13880 e7000} command to connect @value{GDBN} to your E7000:
13883 @item target e7000 @var{port} @var{speed}
13884 Use this form if your E7000 is connected to a serial port. The
13885 @var{port} argument identifies what serial port to use (for example,
13886 @samp{com2}). The third argument is the line speed in bits per second
13887 (for example, @samp{9600}).
13889 @item target e7000 @var{hostname}
13890 If your E7000 is installed as a host on a TCP/IP network, you can just
13891 specify its hostname; @value{GDBN} uses @code{telnet} to connect.
13894 The following special commands are available when debugging with the
13898 @item e7000 @var{command}
13900 @cindex send command to E7000 monitor
13901 This sends the specified @var{command} to the E7000 monitor.
13903 @item ftplogin @var{machine} @var{username} @var{password} @var{dir}
13904 @kindex ftplogin@r{, E7000}
13905 This command records information for subsequent interface with the
13906 E7000 monitor via the FTP protocol: @value{GDBN} will log into the
13907 named @var{machine} using specified @var{username} and @var{password},
13908 and then chdir to the named directory @var{dir}.
13910 @item ftpload @var{file}
13911 @kindex ftpload@r{, E7000}
13912 This command uses credentials recorded by @code{ftplogin} to fetch and
13913 load the named @var{file} from the E7000 monitor.
13916 @kindex drain@r{, E7000}
13917 This command drains any pending text buffers stored on the E7000.
13919 @item set usehardbreakpoints
13920 @itemx show usehardbreakpoints
13921 @kindex set usehardbreakpoints@r{, E7000}
13922 @kindex show usehardbreakpoints@r{, E7000}
13923 @cindex hardware breakpoints, and E7000
13924 These commands set and show the use of hardware breakpoints for all
13925 breakpoints. @xref{Set Breaks, hardware-assisted breakpoint}, for
13926 more information about using hardware breakpoints selectively.
13929 @node Renesas Special
13930 @subsubsection Special @value{GDBN} commands for Renesas micros
13932 Some @value{GDBN} commands are available only for the H8/300:
13936 @kindex set machine
13937 @kindex show machine
13938 @item set machine h8300
13939 @itemx set machine h8300h
13940 Condition @value{GDBN} for one of the two variants of the H8/300
13941 architecture with @samp{set machine}. You can use @samp{show machine}
13942 to check which variant is currently in effect.
13951 @kindex set memory @var{mod}
13952 @cindex memory models, H8/500
13953 @item set memory @var{mod}
13955 Specify which H8/500 memory model (@var{mod}) you are using with
13956 @samp{set memory}; check which memory model is in effect with @samp{show
13957 memory}. The accepted values for @var{mod} are @code{small},
13958 @code{big}, @code{medium}, and @code{compact}.
13963 @subsection Renesas M32R/D and M32R/SDI
13966 @kindex target m32r
13967 @item target m32r @var{dev}
13968 Renesas M32R/D ROM monitor.
13970 @kindex target m32rsdi
13971 @item target m32rsdi @var{dev}
13972 Renesas M32R SDI server, connected via parallel port to the board.
13975 The following @value{GDBN} commands are specific to the M32R monitor:
13978 @item set download-path @var{path}
13979 @kindex set download-path
13980 @cindex find downloadable @sc{srec} files (M32R)
13981 Set the default path for finding donwloadable @sc{srec} files.
13983 @item show download-path
13984 @kindex show download-path
13985 Show the default path for downloadable @sc{srec} files.
13987 @item set board-address @var{addr}
13988 @kindex set board-address
13989 @cindex M32-EVA target board address
13990 Set the IP address for the M32R-EVA target board.
13992 @item show board-address
13993 @kindex show board-address
13994 Show the current IP address of the target board.
13996 @item set server-address @var{addr}
13997 @kindex set server-address
13998 @cindex download server address (M32R)
13999 Set the IP address for the download server, which is the @value{GDBN}'s
14002 @item show server-address
14003 @kindex show server-address
14004 Display the IP address of the download server.
14006 @item upload @r{[}@var{file}@r{]}
14007 @kindex upload@r{, M32R}
14008 Upload the specified @sc{srec} @var{file} via the monitor's Ethernet
14009 upload capability. If no @var{file} argument is given, the current
14010 executable file is uploaded.
14012 @item tload @r{[}@var{file}@r{]}
14013 @kindex tload@r{, M32R}
14014 Test the @code{upload} command.
14017 The following commands are available for M32R/SDI:
14022 @cindex reset SDI connection, M32R
14023 This command resets the SDI connection.
14027 This command shows the SDI connection status.
14030 @kindex debug_chaos
14031 @cindex M32R/Chaos debugging
14032 Instructs the remote that M32R/Chaos debugging is to be used.
14034 @item use_debug_dma
14035 @kindex use_debug_dma
14036 Instructs the remote to use the DEBUG_DMA method of accessing memory.
14039 @kindex use_mon_code
14040 Instructs the remote to use the MON_CODE method of accessing memory.
14043 @kindex use_ib_break
14044 Instructs the remote to set breakpoints by IB break.
14046 @item use_dbt_break
14047 @kindex use_dbt_break
14048 Instructs the remote to set breakpoints by DBT.
14054 The Motorola m68k configuration includes ColdFire support, and
14055 target command for the following ROM monitors.
14059 @kindex target abug
14060 @item target abug @var{dev}
14061 ABug ROM monitor for M68K.
14063 @kindex target cpu32bug
14064 @item target cpu32bug @var{dev}
14065 CPU32BUG monitor, running on a CPU32 (M68K) board.
14067 @kindex target dbug
14068 @item target dbug @var{dev}
14069 dBUG ROM monitor for Motorola ColdFire.
14072 @item target est @var{dev}
14073 EST-300 ICE monitor, running on a CPU32 (M68K) board.
14075 @kindex target rom68k
14076 @item target rom68k @var{dev}
14077 ROM 68K monitor, running on an M68K IDP board.
14083 @kindex target rombug
14084 @item target rombug @var{dev}
14085 ROMBUG ROM monitor for OS/9000.
14089 @node MIPS Embedded
14090 @subsection MIPS Embedded
14092 @cindex MIPS boards
14093 @value{GDBN} can use the MIPS remote debugging protocol to talk to a
14094 MIPS board attached to a serial line. This is available when
14095 you configure @value{GDBN} with @samp{--target=mips-idt-ecoff}.
14098 Use these @value{GDBN} commands to specify the connection to your target board:
14101 @item target mips @var{port}
14102 @kindex target mips @var{port}
14103 To run a program on the board, start up @code{@value{GDBP}} with the
14104 name of your program as the argument. To connect to the board, use the
14105 command @samp{target mips @var{port}}, where @var{port} is the name of
14106 the serial port connected to the board. If the program has not already
14107 been downloaded to the board, you may use the @code{load} command to
14108 download it. You can then use all the usual @value{GDBN} commands.
14110 For example, this sequence connects to the target board through a serial
14111 port, and loads and runs a program called @var{prog} through the
14115 host$ @value{GDBP} @var{prog}
14116 @value{GDBN} is free software and @dots{}
14117 (@value{GDBP}) target mips /dev/ttyb
14118 (@value{GDBP}) load @var{prog}
14122 @item target mips @var{hostname}:@var{portnumber}
14123 On some @value{GDBN} host configurations, you can specify a TCP
14124 connection (for instance, to a serial line managed by a terminal
14125 concentrator) instead of a serial port, using the syntax
14126 @samp{@var{hostname}:@var{portnumber}}.
14128 @item target pmon @var{port}
14129 @kindex target pmon @var{port}
14132 @item target ddb @var{port}
14133 @kindex target ddb @var{port}
14134 NEC's DDB variant of PMON for Vr4300.
14136 @item target lsi @var{port}
14137 @kindex target lsi @var{port}
14138 LSI variant of PMON.
14140 @kindex target r3900
14141 @item target r3900 @var{dev}
14142 Densan DVE-R3900 ROM monitor for Toshiba R3900 Mips.
14144 @kindex target array
14145 @item target array @var{dev}
14146 Array Tech LSI33K RAID controller board.
14152 @value{GDBN} also supports these special commands for MIPS targets:
14155 @item set mipsfpu double
14156 @itemx set mipsfpu single
14157 @itemx set mipsfpu none
14158 @itemx set mipsfpu auto
14159 @itemx show mipsfpu
14160 @kindex set mipsfpu
14161 @kindex show mipsfpu
14162 @cindex MIPS remote floating point
14163 @cindex floating point, MIPS remote
14164 If your target board does not support the MIPS floating point
14165 coprocessor, you should use the command @samp{set mipsfpu none} (if you
14166 need this, you may wish to put the command in your @value{GDBN} init
14167 file). This tells @value{GDBN} how to find the return value of
14168 functions which return floating point values. It also allows
14169 @value{GDBN} to avoid saving the floating point registers when calling
14170 functions on the board. If you are using a floating point coprocessor
14171 with only single precision floating point support, as on the @sc{r4650}
14172 processor, use the command @samp{set mipsfpu single}. The default
14173 double precision floating point coprocessor may be selected using
14174 @samp{set mipsfpu double}.
14176 In previous versions the only choices were double precision or no
14177 floating point, so @samp{set mipsfpu on} will select double precision
14178 and @samp{set mipsfpu off} will select no floating point.
14180 As usual, you can inquire about the @code{mipsfpu} variable with
14181 @samp{show mipsfpu}.
14183 @item set timeout @var{seconds}
14184 @itemx set retransmit-timeout @var{seconds}
14185 @itemx show timeout
14186 @itemx show retransmit-timeout
14187 @cindex @code{timeout}, MIPS protocol
14188 @cindex @code{retransmit-timeout}, MIPS protocol
14189 @kindex set timeout
14190 @kindex show timeout
14191 @kindex set retransmit-timeout
14192 @kindex show retransmit-timeout
14193 You can control the timeout used while waiting for a packet, in the MIPS
14194 remote protocol, with the @code{set timeout @var{seconds}} command. The
14195 default is 5 seconds. Similarly, you can control the timeout used while
14196 waiting for an acknowledgement of a packet with the @code{set
14197 retransmit-timeout @var{seconds}} command. The default is 3 seconds.
14198 You can inspect both values with @code{show timeout} and @code{show
14199 retransmit-timeout}. (These commands are @emph{only} available when
14200 @value{GDBN} is configured for @samp{--target=mips-idt-ecoff}.)
14202 The timeout set by @code{set timeout} does not apply when @value{GDBN}
14203 is waiting for your program to stop. In that case, @value{GDBN} waits
14204 forever because it has no way of knowing how long the program is going
14205 to run before stopping.
14207 @item set syn-garbage-limit @var{num}
14208 @kindex set syn-garbage-limit@r{, MIPS remote}
14209 @cindex synchronize with remote MIPS target
14210 Limit the maximum number of characters @value{GDBN} should ignore when
14211 it tries to synchronize with the remote target. The default is 10
14212 characters. Setting the limit to -1 means there's no limit.
14214 @item show syn-garbage-limit
14215 @kindex show syn-garbage-limit@r{, MIPS remote}
14216 Show the current limit on the number of characters to ignore when
14217 trying to synchronize with the remote system.
14219 @item set monitor-prompt @var{prompt}
14220 @kindex set monitor-prompt@r{, MIPS remote}
14221 @cindex remote monitor prompt
14222 Tell @value{GDBN} to expect the specified @var{prompt} string from the
14223 remote monitor. The default depends on the target:
14233 @item show monitor-prompt
14234 @kindex show monitor-prompt@r{, MIPS remote}
14235 Show the current strings @value{GDBN} expects as the prompt from the
14238 @item set monitor-warnings
14239 @kindex set monitor-warnings@r{, MIPS remote}
14240 Enable or disable monitor warnings about hardware breakpoints. This
14241 has effect only for the @code{lsi} target. When on, @value{GDBN} will
14242 display warning messages whose codes are returned by the @code{lsi}
14243 PMON monitor for breakpoint commands.
14245 @item show monitor-warnings
14246 @kindex show monitor-warnings@r{, MIPS remote}
14247 Show the current setting of printing monitor warnings.
14249 @item pmon @var{command}
14250 @kindex pmon@r{, MIPS remote}
14251 @cindex send PMON command
14252 This command allows sending an arbitrary @var{command} string to the
14253 monitor. The monitor must be in debug mode for this to work.
14256 @node OpenRISC 1000
14257 @subsection OpenRISC 1000
14258 @cindex OpenRISC 1000
14260 @cindex or1k boards
14261 See OR1k Architecture document (@uref{www.opencores.org}) for more information
14262 about platform and commands.
14266 @kindex target jtag
14267 @item target jtag jtag://@var{host}:@var{port}
14269 Connects to remote JTAG server.
14270 JTAG remote server can be either an or1ksim or JTAG server,
14271 connected via parallel port to the board.
14273 Example: @code{target jtag jtag://localhost:9999}
14276 @item or1ksim @var{command}
14277 If connected to @code{or1ksim} OpenRISC 1000 Architectural
14278 Simulator, proprietary commands can be executed.
14280 @kindex info or1k spr
14281 @item info or1k spr
14282 Displays spr groups.
14284 @item info or1k spr @var{group}
14285 @itemx info or1k spr @var{groupno}
14286 Displays register names in selected group.
14288 @item info or1k spr @var{group} @var{register}
14289 @itemx info or1k spr @var{register}
14290 @itemx info or1k spr @var{groupno} @var{registerno}
14291 @itemx info or1k spr @var{registerno}
14292 Shows information about specified spr register.
14295 @item spr @var{group} @var{register} @var{value}
14296 @itemx spr @var{register @var{value}}
14297 @itemx spr @var{groupno} @var{registerno @var{value}}
14298 @itemx spr @var{registerno @var{value}}
14299 Writes @var{value} to specified spr register.
14302 Some implementations of OpenRISC 1000 Architecture also have hardware trace.
14303 It is very similar to @value{GDBN} trace, except it does not interfere with normal
14304 program execution and is thus much faster. Hardware breakpoints/watchpoint
14305 triggers can be set using:
14308 Load effective address/data
14310 Store effective address/data
14312 Access effective address ($SEA or $LEA) or data ($SDATA/$LDATA)
14317 When triggered, it can capture low level data, like: @code{PC}, @code{LSEA},
14318 @code{LDATA}, @code{SDATA}, @code{READSPR}, @code{WRITESPR}, @code{INSTR}.
14320 @code{htrace} commands:
14321 @cindex OpenRISC 1000 htrace
14324 @item hwatch @var{conditional}
14325 Set hardware watchpoint on combination of Load/Store Effecive Address(es)
14326 or Data. For example:
14328 @code{hwatch ($LEA == my_var) && ($LDATA < 50) || ($SEA == my_var) && ($SDATA >= 50)}
14330 @code{hwatch ($LEA == my_var) && ($LDATA < 50) || ($SEA == my_var) && ($SDATA >= 50)}
14334 Display information about current HW trace configuration.
14336 @item htrace trigger @var{conditional}
14337 Set starting criteria for HW trace.
14339 @item htrace qualifier @var{conditional}
14340 Set acquisition qualifier for HW trace.
14342 @item htrace stop @var{conditional}
14343 Set HW trace stopping criteria.
14345 @item htrace record [@var{data}]*
14346 Selects the data to be recorded, when qualifier is met and HW trace was
14349 @item htrace enable
14350 @itemx htrace disable
14351 Enables/disables the HW trace.
14353 @item htrace rewind [@var{filename}]
14354 Clears currently recorded trace data.
14356 If filename is specified, new trace file is made and any newly collected data
14357 will be written there.
14359 @item htrace print [@var{start} [@var{len}]]
14360 Prints trace buffer, using current record configuration.
14362 @item htrace mode continuous
14363 Set continuous trace mode.
14365 @item htrace mode suspend
14366 Set suspend trace mode.
14371 @subsection PowerPC
14374 @kindex target dink32
14375 @item target dink32 @var{dev}
14376 DINK32 ROM monitor.
14378 @kindex target ppcbug
14379 @item target ppcbug @var{dev}
14380 @kindex target ppcbug1
14381 @item target ppcbug1 @var{dev}
14382 PPCBUG ROM monitor for PowerPC.
14385 @item target sds @var{dev}
14386 SDS monitor, running on a PowerPC board (such as Motorola's ADS).
14389 @cindex SDS protocol
14390 The following commands specifi to the SDS protocol are supported
14394 @item set sdstimeout @var{nsec}
14395 @kindex set sdstimeout
14396 Set the timeout for SDS protocol reads to be @var{nsec} seconds. The
14397 default is 2 seconds.
14399 @item show sdstimeout
14400 @kindex show sdstimeout
14401 Show the current value of the SDS timeout.
14403 @item sds @var{command}
14404 @kindex sds@r{, a command}
14405 Send the specified @var{command} string to the SDS monitor.
14410 @subsection HP PA Embedded
14414 @kindex target op50n
14415 @item target op50n @var{dev}
14416 OP50N monitor, running on an OKI HPPA board.
14418 @kindex target w89k
14419 @item target w89k @var{dev}
14420 W89K monitor, running on a Winbond HPPA board.
14425 @subsection Renesas SH
14429 @kindex target hms@r{, with Renesas SH}
14430 @item target hms @var{dev}
14431 A Renesas SH board attached via serial line to your host. Use special
14432 commands @code{device} and @code{speed} to control the serial line and
14433 the communications speed used.
14435 @kindex target e7000@r{, with Renesas SH}
14436 @item target e7000 @var{dev}
14437 E7000 emulator for Renesas SH.
14439 @kindex target sh3@r{, with SH}
14440 @kindex target sh3e@r{, with SH}
14441 @item target sh3 @var{dev}
14442 @item target sh3e @var{dev}
14443 Renesas SH-3 and SH-3E target systems.
14448 @subsection Tsqware Sparclet
14452 @value{GDBN} enables developers to debug tasks running on
14453 Sparclet targets from a Unix host.
14454 @value{GDBN} uses code that runs on
14455 both the Unix host and on the Sparclet target. The program
14456 @code{@value{GDBP}} is installed and executed on the Unix host.
14459 @item remotetimeout @var{args}
14460 @kindex remotetimeout
14461 @value{GDBN} supports the option @code{remotetimeout}.
14462 This option is set by the user, and @var{args} represents the number of
14463 seconds @value{GDBN} waits for responses.
14466 @cindex compiling, on Sparclet
14467 When compiling for debugging, include the options @samp{-g} to get debug
14468 information and @samp{-Ttext} to relocate the program to where you wish to
14469 load it on the target. You may also want to add the options @samp{-n} or
14470 @samp{-N} in order to reduce the size of the sections. Example:
14473 sparclet-aout-gcc prog.c -Ttext 0x12010000 -g -o prog -N
14476 You can use @code{objdump} to verify that the addresses are what you intended:
14479 sparclet-aout-objdump --headers --syms prog
14482 @cindex running, on Sparclet
14484 your Unix execution search path to find @value{GDBN}, you are ready to
14485 run @value{GDBN}. From your Unix host, run @code{@value{GDBP}}
14486 (or @code{sparclet-aout-gdb}, depending on your installation).
14488 @value{GDBN} comes up showing the prompt:
14495 * Sparclet File:: Setting the file to debug
14496 * Sparclet Connection:: Connecting to Sparclet
14497 * Sparclet Download:: Sparclet download
14498 * Sparclet Execution:: Running and debugging
14501 @node Sparclet File
14502 @subsubsection Setting file to debug
14504 The @value{GDBN} command @code{file} lets you choose with program to debug.
14507 (gdbslet) file prog
14511 @value{GDBN} then attempts to read the symbol table of @file{prog}.
14512 @value{GDBN} locates
14513 the file by searching the directories listed in the command search
14515 If the file was compiled with debug information (option "-g"), source
14516 files will be searched as well.
14517 @value{GDBN} locates
14518 the source files by searching the directories listed in the directory search
14519 path (@pxref{Environment, ,Your program's environment}).
14521 to find a file, it displays a message such as:
14524 prog: No such file or directory.
14527 When this happens, add the appropriate directories to the search paths with
14528 the @value{GDBN} commands @code{path} and @code{dir}, and execute the
14529 @code{target} command again.
14531 @node Sparclet Connection
14532 @subsubsection Connecting to Sparclet
14534 The @value{GDBN} command @code{target} lets you connect to a Sparclet target.
14535 To connect to a target on serial port ``@code{ttya}'', type:
14538 (gdbslet) target sparclet /dev/ttya
14539 Remote target sparclet connected to /dev/ttya
14540 main () at ../prog.c:3
14544 @value{GDBN} displays messages like these:
14550 @node Sparclet Download
14551 @subsubsection Sparclet download
14553 @cindex download to Sparclet
14554 Once connected to the Sparclet target,
14555 you can use the @value{GDBN}
14556 @code{load} command to download the file from the host to the target.
14557 The file name and load offset should be given as arguments to the @code{load}
14559 Since the file format is aout, the program must be loaded to the starting
14560 address. You can use @code{objdump} to find out what this value is. The load
14561 offset is an offset which is added to the VMA (virtual memory address)
14562 of each of the file's sections.
14563 For instance, if the program
14564 @file{prog} was linked to text address 0x1201000, with data at 0x12010160
14565 and bss at 0x12010170, in @value{GDBN}, type:
14568 (gdbslet) load prog 0x12010000
14569 Loading section .text, size 0xdb0 vma 0x12010000
14572 If the code is loaded at a different address then what the program was linked
14573 to, you may need to use the @code{section} and @code{add-symbol-file} commands
14574 to tell @value{GDBN} where to map the symbol table.
14576 @node Sparclet Execution
14577 @subsubsection Running and debugging
14579 @cindex running and debugging Sparclet programs
14580 You can now begin debugging the task using @value{GDBN}'s execution control
14581 commands, @code{b}, @code{step}, @code{run}, etc. See the @value{GDBN}
14582 manual for the list of commands.
14586 Breakpoint 1 at 0x12010000: file prog.c, line 3.
14588 Starting program: prog
14589 Breakpoint 1, main (argc=1, argv=0xeffff21c) at prog.c:3
14590 3 char *symarg = 0;
14592 4 char *execarg = "hello!";
14597 @subsection Fujitsu Sparclite
14601 @kindex target sparclite
14602 @item target sparclite @var{dev}
14603 Fujitsu sparclite boards, used only for the purpose of loading.
14604 You must use an additional command to debug the program.
14605 For example: target remote @var{dev} using @value{GDBN} standard
14611 @subsection Tandem ST2000
14613 @value{GDBN} may be used with a Tandem ST2000 phone switch, running Tandem's
14616 To connect your ST2000 to the host system, see the manufacturer's
14617 manual. Once the ST2000 is physically attached, you can run:
14620 target st2000 @var{dev} @var{speed}
14624 to establish it as your debugging environment. @var{dev} is normally
14625 the name of a serial device, such as @file{/dev/ttya}, connected to the
14626 ST2000 via a serial line. You can instead specify @var{dev} as a TCP
14627 connection (for example, to a serial line attached via a terminal
14628 concentrator) using the syntax @code{@var{hostname}:@var{portnumber}}.
14630 The @code{load} and @code{attach} commands are @emph{not} defined for
14631 this target; you must load your program into the ST2000 as you normally
14632 would for standalone operation. @value{GDBN} reads debugging information
14633 (such as symbols) from a separate, debugging version of the program
14634 available on your host computer.
14635 @c FIXME!! This is terribly vague; what little content is here is
14636 @c basically hearsay.
14638 @cindex ST2000 auxiliary commands
14639 These auxiliary @value{GDBN} commands are available to help you with the ST2000
14643 @item st2000 @var{command}
14644 @kindex st2000 @var{cmd}
14645 @cindex STDBUG commands (ST2000)
14646 @cindex commands to STDBUG (ST2000)
14647 Send a @var{command} to the STDBUG monitor. See the manufacturer's
14648 manual for available commands.
14651 @cindex connect (to STDBUG)
14652 Connect the controlling terminal to the STDBUG command monitor. When
14653 you are done interacting with STDBUG, typing either of two character
14654 sequences gets you back to the @value{GDBN} command prompt:
14655 @kbd{@key{RET}~.} (Return, followed by tilde and period) or
14656 @kbd{@key{RET}~@key{C-d}} (Return, followed by tilde and control-D).
14660 @subsection Zilog Z8000
14663 @cindex simulator, Z8000
14664 @cindex Zilog Z8000 simulator
14666 When configured for debugging Zilog Z8000 targets, @value{GDBN} includes
14669 For the Z8000 family, @samp{target sim} simulates either the Z8002 (the
14670 unsegmented variant of the Z8000 architecture) or the Z8001 (the
14671 segmented variant). The simulator recognizes which architecture is
14672 appropriate by inspecting the object code.
14675 @item target sim @var{args}
14677 @kindex target sim@r{, with Z8000}
14678 Debug programs on a simulated CPU. If the simulator supports setup
14679 options, specify them via @var{args}.
14683 After specifying this target, you can debug programs for the simulated
14684 CPU in the same style as programs for your host computer; use the
14685 @code{file} command to load a new program image, the @code{run} command
14686 to run your program, and so on.
14688 As well as making available all the usual machine registers
14689 (@pxref{Registers, ,Registers}), the Z8000 simulator provides three
14690 additional items of information as specially named registers:
14695 Counts clock-ticks in the simulator.
14698 Counts instructions run in the simulator.
14701 Execution time in 60ths of a second.
14705 You can refer to these values in @value{GDBN} expressions with the usual
14706 conventions; for example, @w{@samp{b fputc if $cycles>5000}} sets a
14707 conditional breakpoint that suspends only after at least 5000
14708 simulated clock ticks.
14711 @subsection Atmel AVR
14714 When configured for debugging the Atmel AVR, @value{GDBN} supports the
14715 following AVR-specific commands:
14718 @item info io_registers
14719 @kindex info io_registers@r{, AVR}
14720 @cindex I/O registers (Atmel AVR)
14721 This command displays information about the AVR I/O registers. For
14722 each register, @value{GDBN} prints its number and value.
14729 When configured for debugging CRIS, @value{GDBN} provides the
14730 following CRIS-specific commands:
14733 @item set cris-version @var{ver}
14734 @cindex CRIS version
14735 Set the current CRIS version to @var{ver}, either @samp{10} or @samp{32}.
14736 The CRIS version affects register names and sizes. This command is useful in
14737 case autodetection of the CRIS version fails.
14739 @item show cris-version
14740 Show the current CRIS version.
14742 @item set cris-dwarf2-cfi
14743 @cindex DWARF-2 CFI and CRIS
14744 Set the usage of DWARF-2 CFI for CRIS debugging. The default is @samp{on}.
14745 Change to @samp{off} when using @code{gcc-cris} whose version is below
14748 @item show cris-dwarf2-cfi
14749 Show the current state of using DWARF-2 CFI.
14751 @item set cris-mode @var{mode}
14753 Set the current CRIS mode to @var{mode}. It should only be changed when
14754 debugging in guru mode, in which case it should be set to
14755 @samp{guru} (the default is @samp{normal}).
14757 @item show cris-mode
14758 Show the current CRIS mode.
14762 @subsection Renesas Super-H
14765 For the Renesas Super-H processor, @value{GDBN} provides these
14770 @kindex regs@r{, Super-H}
14771 Show the values of all Super-H registers.
14775 @subsection Windows CE
14778 The following commands are available for Windows CE:
14781 @item set remotedirectory @var{dir}
14782 @kindex set remotedirectory
14783 Tell @value{GDBN} to upload files from the named directory @var{dir}.
14784 The default is @file{/gdb}, i.e.@: the root directory on the current
14787 @item show remotedirectory
14788 @kindex show remotedirectory
14789 Show the current value of the upload directory.
14791 @item set remoteupload @var{method}
14792 @kindex set remoteupload
14793 Set the method used to upload files to remote device. Valid values
14794 for @var{method} are @samp{always}, @samp{newer}, and @samp{never}.
14795 The default is @samp{newer}.
14797 @item show remoteupload
14798 @kindex show remoteupload
14799 Show the current setting of the upload method.
14801 @item set remoteaddhost
14802 @kindex set remoteaddhost
14803 Tell @value{GDBN} whether to add this host to the remote stub's
14804 arguments when you debug over a network.
14806 @item show remoteaddhost
14807 @kindex show remoteaddhost
14808 Show whether to add this host to remote stub's arguments when
14809 debugging over a network.
14813 @node Architectures
14814 @section Architectures
14816 This section describes characteristics of architectures that affect
14817 all uses of @value{GDBN} with the architecture, both native and cross.
14824 * HPPA:: HP PA architecture
14828 @subsection x86 Architecture-specific issues.
14831 @item set struct-convention @var{mode}
14832 @kindex set struct-convention
14833 @cindex struct return convention
14834 @cindex struct/union returned in registers
14835 Set the convention used by the inferior to return @code{struct}s and
14836 @code{union}s from functions to @var{mode}. Possible values of
14837 @var{mode} are @code{"pcc"}, @code{"reg"}, and @code{"default"} (the
14838 default). @code{"default"} or @code{"pcc"} means that @code{struct}s
14839 are returned on the stack, while @code{"reg"} means that a
14840 @code{struct} or a @code{union} whose size is 1, 2, 4, or 8 bytes will
14841 be returned in a register.
14843 @item show struct-convention
14844 @kindex show struct-convention
14845 Show the current setting of the convention to return @code{struct}s
14854 @kindex set rstack_high_address
14855 @cindex AMD 29K register stack
14856 @cindex register stack, AMD29K
14857 @item set rstack_high_address @var{address}
14858 On AMD 29000 family processors, registers are saved in a separate
14859 @dfn{register stack}. There is no way for @value{GDBN} to determine the
14860 extent of this stack. Normally, @value{GDBN} just assumes that the
14861 stack is ``large enough''. This may result in @value{GDBN} referencing
14862 memory locations that do not exist. If necessary, you can get around
14863 this problem by specifying the ending address of the register stack with
14864 the @code{set rstack_high_address} command. The argument should be an
14865 address, which you probably want to precede with @samp{0x} to specify in
14868 @kindex show rstack_high_address
14869 @item show rstack_high_address
14870 Display the current limit of the register stack, on AMD 29000 family
14878 See the following section.
14883 @cindex stack on Alpha
14884 @cindex stack on MIPS
14885 @cindex Alpha stack
14887 Alpha- and MIPS-based computers use an unusual stack frame, which
14888 sometimes requires @value{GDBN} to search backward in the object code to
14889 find the beginning of a function.
14891 @cindex response time, MIPS debugging
14892 To improve response time (especially for embedded applications, where
14893 @value{GDBN} may be restricted to a slow serial line for this search)
14894 you may want to limit the size of this search, using one of these
14898 @cindex @code{heuristic-fence-post} (Alpha, MIPS)
14899 @item set heuristic-fence-post @var{limit}
14900 Restrict @value{GDBN} to examining at most @var{limit} bytes in its
14901 search for the beginning of a function. A value of @var{0} (the
14902 default) means there is no limit. However, except for @var{0}, the
14903 larger the limit the more bytes @code{heuristic-fence-post} must search
14904 and therefore the longer it takes to run. You should only need to use
14905 this command when debugging a stripped executable.
14907 @item show heuristic-fence-post
14908 Display the current limit.
14912 These commands are available @emph{only} when @value{GDBN} is configured
14913 for debugging programs on Alpha or MIPS processors.
14915 Several MIPS-specific commands are available when debugging MIPS
14919 @item set mips saved-gpreg-size @var{size}
14920 @kindex set mips saved-gpreg-size
14921 @cindex MIPS GP register size on stack
14922 Set the size of MIPS general-purpose registers saved on the stack.
14923 The argument @var{size} can be one of the following:
14927 32-bit GP registers
14929 64-bit GP registers
14931 Use the target's default setting or autodetect the saved size from the
14932 information contained in the executable. This is the default
14935 @item show mips saved-gpreg-size
14936 @kindex show mips saved-gpreg-size
14937 Show the current size of MIPS GP registers on the stack.
14939 @item set mips stack-arg-size @var{size}
14940 @kindex set mips stack-arg-size
14941 @cindex MIPS stack space for arguments
14942 Set the amount of stack space reserved for arguments to functions.
14943 The argument can be one of @code{"32"}, @code{"64"} or @code{"auto"}
14946 @item set mips abi @var{arg}
14947 @kindex set mips abi
14948 @cindex set ABI for MIPS
14949 Tell @value{GDBN} which MIPS ABI is used by the inferior. Possible
14950 values of @var{arg} are:
14954 The default ABI associated with the current binary (this is the
14965 @item show mips abi
14966 @kindex show mips abi
14967 Show the MIPS ABI used by @value{GDBN} to debug the inferior.
14970 @itemx show mipsfpu
14971 @xref{MIPS Embedded, set mipsfpu}.
14973 @item set mips mask-address @var{arg}
14974 @kindex set mips mask-address
14975 @cindex MIPS addresses, masking
14976 This command determines whether the most-significant 32 bits of 64-bit
14977 MIPS addresses are masked off. The argument @var{arg} can be
14978 @samp{on}, @samp{off}, or @samp{auto}. The latter is the default
14979 setting, which lets @value{GDBN} determine the correct value.
14981 @item show mips mask-address
14982 @kindex show mips mask-address
14983 Show whether the upper 32 bits of MIPS addresses are masked off or
14986 @item set remote-mips64-transfers-32bit-regs
14987 @kindex set remote-mips64-transfers-32bit-regs
14988 This command controls compatibility with 64-bit MIPS targets that
14989 transfer data in 32-bit quantities. If you have an old MIPS 64 target
14990 that transfers 32 bits for some registers, like @sc{sr} and @sc{fsr},
14991 and 64 bits for other registers, set this option to @samp{on}.
14993 @item show remote-mips64-transfers-32bit-regs
14994 @kindex show remote-mips64-transfers-32bit-regs
14995 Show the current setting of compatibility with older MIPS 64 targets.
14997 @item set debug mips
14998 @kindex set debug mips
14999 This command turns on and off debugging messages for the MIPS-specific
15000 target code in @value{GDBN}.
15002 @item show debug mips
15003 @kindex show debug mips
15004 Show the current setting of MIPS debugging messages.
15010 @cindex HPPA support
15012 When @value{GDBN} is debugging te HP PA architecture, it provides the
15013 following special commands:
15016 @item set debug hppa
15017 @kindex set debug hppa
15018 THis command determines whether HPPA architecture specific debugging
15019 messages are to be displayed.
15021 @item show debug hppa
15022 Show whether HPPA debugging messages are displayed.
15024 @item maint print unwind @var{address}
15025 @kindex maint print unwind@r{, HPPA}
15026 This command displays the contents of the unwind table entry at the
15027 given @var{address}.
15032 @node Controlling GDB
15033 @chapter Controlling @value{GDBN}
15035 You can alter the way @value{GDBN} interacts with you by using the
15036 @code{set} command. For commands controlling how @value{GDBN} displays
15037 data, see @ref{Print Settings, ,Print settings}. Other settings are
15042 * Editing:: Command editing
15043 * Command History:: Command history
15044 * Screen Size:: Screen size
15045 * Numbers:: Numbers
15046 * ABI:: Configuring the current ABI
15047 * Messages/Warnings:: Optional warnings and messages
15048 * Debugging Output:: Optional messages about internal happenings
15056 @value{GDBN} indicates its readiness to read a command by printing a string
15057 called the @dfn{prompt}. This string is normally @samp{(@value{GDBP})}. You
15058 can change the prompt string with the @code{set prompt} command. For
15059 instance, when debugging @value{GDBN} with @value{GDBN}, it is useful to change
15060 the prompt in one of the @value{GDBN} sessions so that you can always tell
15061 which one you are talking to.
15063 @emph{Note:} @code{set prompt} does not add a space for you after the
15064 prompt you set. This allows you to set a prompt which ends in a space
15065 or a prompt that does not.
15069 @item set prompt @var{newprompt}
15070 Directs @value{GDBN} to use @var{newprompt} as its prompt string henceforth.
15072 @kindex show prompt
15074 Prints a line of the form: @samp{Gdb's prompt is: @var{your-prompt}}
15078 @section Command editing
15080 @cindex command line editing
15082 @value{GDBN} reads its input commands via the @dfn{Readline} interface. This
15083 @sc{gnu} library provides consistent behavior for programs which provide a
15084 command line interface to the user. Advantages are @sc{gnu} Emacs-style
15085 or @dfn{vi}-style inline editing of commands, @code{csh}-like history
15086 substitution, and a storage and recall of command history across
15087 debugging sessions.
15089 You may control the behavior of command line editing in @value{GDBN} with the
15090 command @code{set}.
15093 @kindex set editing
15096 @itemx set editing on
15097 Enable command line editing (enabled by default).
15099 @item set editing off
15100 Disable command line editing.
15102 @kindex show editing
15104 Show whether command line editing is enabled.
15107 @xref{Command Line Editing}, for more details about the Readline
15108 interface. Users unfamiliar with @sc{gnu} Emacs or @code{vi} are
15109 encouraged to read that chapter.
15111 @node Command History
15112 @section Command history
15113 @cindex command history
15115 @value{GDBN} can keep track of the commands you type during your
15116 debugging sessions, so that you can be certain of precisely what
15117 happened. Use these commands to manage the @value{GDBN} command
15120 @value{GDBN} uses the @sc{gnu} History library, a part of the Readline
15121 package, to provide the history facility. @xref{Using History
15122 Interactively}, for the detailed description of the History library.
15124 To issue a command to @value{GDBN} without affecting certain aspects of
15125 the state which is seen by users, prefix it with @samp{server }. This
15126 means that this command will not affect the command history, nor will it
15127 affect @value{GDBN}'s notion of which command to repeat if @key{RET} is
15128 pressed on a line by itself.
15130 @cindex @code{server}, command prefix
15131 The server prefix does not affect the recording of values into the value
15132 history; to print a value without recording it into the value history,
15133 use the @code{output} command instead of the @code{print} command.
15135 Here is the description of @value{GDBN} commands related to command
15139 @cindex history substitution
15140 @cindex history file
15141 @kindex set history filename
15142 @cindex @env{GDBHISTFILE}, environment variable
15143 @item set history filename @var{fname}
15144 Set the name of the @value{GDBN} command history file to @var{fname}.
15145 This is the file where @value{GDBN} reads an initial command history
15146 list, and where it writes the command history from this session when it
15147 exits. You can access this list through history expansion or through
15148 the history command editing characters listed below. This file defaults
15149 to the value of the environment variable @code{GDBHISTFILE}, or to
15150 @file{./.gdb_history} (@file{./_gdb_history} on MS-DOS) if this variable
15153 @cindex save command history
15154 @kindex set history save
15155 @item set history save
15156 @itemx set history save on
15157 Record command history in a file, whose name may be specified with the
15158 @code{set history filename} command. By default, this option is disabled.
15160 @item set history save off
15161 Stop recording command history in a file.
15163 @cindex history size
15164 @kindex set history size
15165 @cindex @env{HISTSIZE}, environment variable
15166 @item set history size @var{size}
15167 Set the number of commands which @value{GDBN} keeps in its history list.
15168 This defaults to the value of the environment variable
15169 @code{HISTSIZE}, or to 256 if this variable is not set.
15172 History expansion assigns special meaning to the character @kbd{!}.
15173 @xref{Event Designators}, for more details.
15175 @cindex history expansion, turn on/off
15176 Since @kbd{!} is also the logical not operator in C, history expansion
15177 is off by default. If you decide to enable history expansion with the
15178 @code{set history expansion on} command, you may sometimes need to
15179 follow @kbd{!} (when it is used as logical not, in an expression) with
15180 a space or a tab to prevent it from being expanded. The readline
15181 history facilities do not attempt substitution on the strings
15182 @kbd{!=} and @kbd{!(}, even when history expansion is enabled.
15184 The commands to control history expansion are:
15187 @item set history expansion on
15188 @itemx set history expansion
15189 @kindex set history expansion
15190 Enable history expansion. History expansion is off by default.
15192 @item set history expansion off
15193 Disable history expansion.
15196 @kindex show history
15198 @itemx show history filename
15199 @itemx show history save
15200 @itemx show history size
15201 @itemx show history expansion
15202 These commands display the state of the @value{GDBN} history parameters.
15203 @code{show history} by itself displays all four states.
15208 @kindex show commands
15209 @cindex show last commands
15210 @cindex display command history
15211 @item show commands
15212 Display the last ten commands in the command history.
15214 @item show commands @var{n}
15215 Print ten commands centered on command number @var{n}.
15217 @item show commands +
15218 Print ten commands just after the commands last printed.
15222 @section Screen size
15223 @cindex size of screen
15224 @cindex pauses in output
15226 Certain commands to @value{GDBN} may produce large amounts of
15227 information output to the screen. To help you read all of it,
15228 @value{GDBN} pauses and asks you for input at the end of each page of
15229 output. Type @key{RET} when you want to continue the output, or @kbd{q}
15230 to discard the remaining output. Also, the screen width setting
15231 determines when to wrap lines of output. Depending on what is being
15232 printed, @value{GDBN} tries to break the line at a readable place,
15233 rather than simply letting it overflow onto the following line.
15235 Normally @value{GDBN} knows the size of the screen from the terminal
15236 driver software. For example, on Unix @value{GDBN} uses the termcap data base
15237 together with the value of the @code{TERM} environment variable and the
15238 @code{stty rows} and @code{stty cols} settings. If this is not correct,
15239 you can override it with the @code{set height} and @code{set
15246 @kindex show height
15247 @item set height @var{lpp}
15249 @itemx set width @var{cpl}
15251 These @code{set} commands specify a screen height of @var{lpp} lines and
15252 a screen width of @var{cpl} characters. The associated @code{show}
15253 commands display the current settings.
15255 If you specify a height of zero lines, @value{GDBN} does not pause during
15256 output no matter how long the output is. This is useful if output is to a
15257 file or to an editor buffer.
15259 Likewise, you can specify @samp{set width 0} to prevent @value{GDBN}
15260 from wrapping its output.
15262 @item set pagination on
15263 @itemx set pagination off
15264 @kindex set pagination
15265 Turn the output pagination on or off; the default is on. Turning
15266 pagination off is the alternative to @code{set height 0}.
15268 @item show pagination
15269 @kindex show pagination
15270 Show the current pagination mode.
15275 @cindex number representation
15276 @cindex entering numbers
15278 You can always enter numbers in octal, decimal, or hexadecimal in
15279 @value{GDBN} by the usual conventions: octal numbers begin with
15280 @samp{0}, decimal numbers end with @samp{.}, and hexadecimal numbers
15281 begin with @samp{0x}. Numbers that neither begin with @samp{0} or
15282 @samp{0x}, nor end with a @samp{.} are, by default, entered in base
15283 10; likewise, the default display for numbers---when no particular
15284 format is specified---is base 10. You can change the default base for
15285 both input and output with the commands described below.
15288 @kindex set input-radix
15289 @item set input-radix @var{base}
15290 Set the default base for numeric input. Supported choices
15291 for @var{base} are decimal 8, 10, or 16. @var{base} must itself be
15292 specified either unambiguously or using the current input radix; for
15296 set input-radix 012
15297 set input-radix 10.
15298 set input-radix 0xa
15302 sets the input base to decimal. On the other hand, @samp{set input-radix 10}
15303 leaves the input radix unchanged, no matter what it was, since
15304 @samp{10}, being without any leading or trailing signs of its base, is
15305 interpreted in the current radix. Thus, if the current radix is 16,
15306 @samp{10} is interpreted in hex, i.e.@: as 16 decimal, which doesn't
15309 @kindex set output-radix
15310 @item set output-radix @var{base}
15311 Set the default base for numeric display. Supported choices
15312 for @var{base} are decimal 8, 10, or 16. @var{base} must itself be
15313 specified either unambiguously or using the current input radix.
15315 @kindex show input-radix
15316 @item show input-radix
15317 Display the current default base for numeric input.
15319 @kindex show output-radix
15320 @item show output-radix
15321 Display the current default base for numeric display.
15323 @item set radix @r{[}@var{base}@r{]}
15327 These commands set and show the default base for both input and output
15328 of numbers. @code{set radix} sets the radix of input and output to
15329 the same base; without an argument, it resets the radix back to its
15330 default value of 10.
15335 @section Configuring the current ABI
15337 @value{GDBN} can determine the @dfn{ABI} (Application Binary Interface) of your
15338 application automatically. However, sometimes you need to override its
15339 conclusions. Use these commands to manage @value{GDBN}'s view of the
15346 One @value{GDBN} configuration can debug binaries for multiple operating
15347 system targets, either via remote debugging or native emulation.
15348 @value{GDBN} will autodetect the @dfn{OS ABI} (Operating System ABI) in use,
15349 but you can override its conclusion using the @code{set osabi} command.
15350 One example where this is useful is in debugging of binaries which use
15351 an alternate C library (e.g.@: @sc{uClibc} for @sc{gnu}/Linux) which does
15352 not have the same identifying marks that the standard C library for your
15357 Show the OS ABI currently in use.
15360 With no argument, show the list of registered available OS ABI's.
15362 @item set osabi @var{abi}
15363 Set the current OS ABI to @var{abi}.
15366 @cindex float promotion
15368 Generally, the way that an argument of type @code{float} is passed to a
15369 function depends on whether the function is prototyped. For a prototyped
15370 (i.e.@: ANSI/ISO style) function, @code{float} arguments are passed unchanged,
15371 according to the architecture's convention for @code{float}. For unprototyped
15372 (i.e.@: K&R style) functions, @code{float} arguments are first promoted to type
15373 @code{double} and then passed.
15375 Unfortunately, some forms of debug information do not reliably indicate whether
15376 a function is prototyped. If @value{GDBN} calls a function that is not marked
15377 as prototyped, it consults @kbd{set coerce-float-to-double}.
15380 @kindex set coerce-float-to-double
15381 @item set coerce-float-to-double
15382 @itemx set coerce-float-to-double on
15383 Arguments of type @code{float} will be promoted to @code{double} when passed
15384 to an unprototyped function. This is the default setting.
15386 @item set coerce-float-to-double off
15387 Arguments of type @code{float} will be passed directly to unprototyped
15390 @kindex show coerce-float-to-double
15391 @item show coerce-float-to-double
15392 Show the current setting of promoting @code{float} to @code{double}.
15396 @kindex show cp-abi
15397 @value{GDBN} needs to know the ABI used for your program's C@t{++}
15398 objects. The correct C@t{++} ABI depends on which C@t{++} compiler was
15399 used to build your application. @value{GDBN} only fully supports
15400 programs with a single C@t{++} ABI; if your program contains code using
15401 multiple C@t{++} ABI's or if @value{GDBN} can not identify your
15402 program's ABI correctly, you can tell @value{GDBN} which ABI to use.
15403 Currently supported ABI's include ``gnu-v2'', for @code{g++} versions
15404 before 3.0, ``gnu-v3'', for @code{g++} versions 3.0 and later, and
15405 ``hpaCC'' for the HP ANSI C@t{++} compiler. Other C@t{++} compilers may
15406 use the ``gnu-v2'' or ``gnu-v3'' ABI's as well. The default setting is
15411 Show the C@t{++} ABI currently in use.
15414 With no argument, show the list of supported C@t{++} ABI's.
15416 @item set cp-abi @var{abi}
15417 @itemx set cp-abi auto
15418 Set the current C@t{++} ABI to @var{abi}, or return to automatic detection.
15421 @node Messages/Warnings
15422 @section Optional warnings and messages
15424 @cindex verbose operation
15425 @cindex optional warnings
15426 By default, @value{GDBN} is silent about its inner workings. If you are
15427 running on a slow machine, you may want to use the @code{set verbose}
15428 command. This makes @value{GDBN} tell you when it does a lengthy
15429 internal operation, so you will not think it has crashed.
15431 Currently, the messages controlled by @code{set verbose} are those
15432 which announce that the symbol table for a source file is being read;
15433 see @code{symbol-file} in @ref{Files, ,Commands to specify files}.
15436 @kindex set verbose
15437 @item set verbose on
15438 Enables @value{GDBN} output of certain informational messages.
15440 @item set verbose off
15441 Disables @value{GDBN} output of certain informational messages.
15443 @kindex show verbose
15445 Displays whether @code{set verbose} is on or off.
15448 By default, if @value{GDBN} encounters bugs in the symbol table of an
15449 object file, it is silent; but if you are debugging a compiler, you may
15450 find this information useful (@pxref{Symbol Errors, ,Errors reading
15455 @kindex set complaints
15456 @item set complaints @var{limit}
15457 Permits @value{GDBN} to output @var{limit} complaints about each type of
15458 unusual symbols before becoming silent about the problem. Set
15459 @var{limit} to zero to suppress all complaints; set it to a large number
15460 to prevent complaints from being suppressed.
15462 @kindex show complaints
15463 @item show complaints
15464 Displays how many symbol complaints @value{GDBN} is permitted to produce.
15468 By default, @value{GDBN} is cautious, and asks what sometimes seems to be a
15469 lot of stupid questions to confirm certain commands. For example, if
15470 you try to run a program which is already running:
15474 The program being debugged has been started already.
15475 Start it from the beginning? (y or n)
15478 If you are willing to unflinchingly face the consequences of your own
15479 commands, you can disable this ``feature'':
15483 @kindex set confirm
15485 @cindex confirmation
15486 @cindex stupid questions
15487 @item set confirm off
15488 Disables confirmation requests.
15490 @item set confirm on
15491 Enables confirmation requests (the default).
15493 @kindex show confirm
15495 Displays state of confirmation requests.
15499 @node Debugging Output
15500 @section Optional messages about internal happenings
15501 @cindex optional debugging messages
15503 @value{GDBN} has commands that enable optional debugging messages from
15504 various @value{GDBN} subsystems; normally these commands are of
15505 interest to @value{GDBN} maintainers, or when reporting a bug. This
15506 section documents those commands.
15509 @kindex set exec-done-display
15510 @item set exec-done-display
15511 Turns on or off the notification of asynchronous commands'
15512 completion. When on, @value{GDBN} will print a message when an
15513 asynchronous command finishes its execution. The default is off.
15514 @kindex show exec-done-display
15515 @item show exec-done-display
15516 Displays the current setting of asynchronous command completion
15519 @cindex gdbarch debugging info
15520 @cindex architecture debugging info
15521 @item set debug arch
15522 Turns on or off display of gdbarch debugging info. The default is off
15524 @item show debug arch
15525 Displays the current state of displaying gdbarch debugging info.
15526 @item set debug aix-thread
15527 @cindex AIX threads
15528 Display debugging messages about inner workings of the AIX thread
15530 @item show debug aix-thread
15531 Show the current state of AIX thread debugging info display.
15532 @item set debug event
15533 @cindex event debugging info
15534 Turns on or off display of @value{GDBN} event debugging info. The
15536 @item show debug event
15537 Displays the current state of displaying @value{GDBN} event debugging
15539 @item set debug expression
15540 @cindex expression debugging info
15541 Turns on or off display of debugging info about @value{GDBN}
15542 expression parsing. The default is off.
15543 @item show debug expression
15544 Displays the current state of displaying debugging info about
15545 @value{GDBN} expression parsing.
15546 @item set debug frame
15547 @cindex frame debugging info
15548 Turns on or off display of @value{GDBN} frame debugging info. The
15550 @item show debug frame
15551 Displays the current state of displaying @value{GDBN} frame debugging
15553 @item set debug infrun
15554 @cindex inferior debugging info
15555 Turns on or off display of @value{GDBN} debugging info for running the inferior.
15556 The default is off. @file{infrun.c} contains GDB's runtime state machine used
15557 for implementing operations such as single-stepping the inferior.
15558 @item show debug infrun
15559 Displays the current state of @value{GDBN} inferior debugging.
15560 @item set debug lin-lwp
15561 @cindex @sc{gnu}/Linux LWP debug messages
15562 @cindex Linux lightweight processes
15563 Turns on or off debugging messages from the Linux LWP debug support.
15564 @item show debug lin-lwp
15565 Show the current state of Linux LWP debugging messages.
15566 @item set debug observer
15567 @cindex observer debugging info
15568 Turns on or off display of @value{GDBN} observer debugging. This
15569 includes info such as the notification of observable events.
15570 @item show debug observer
15571 Displays the current state of observer debugging.
15572 @item set debug overload
15573 @cindex C@t{++} overload debugging info
15574 Turns on or off display of @value{GDBN} C@t{++} overload debugging
15575 info. This includes info such as ranking of functions, etc. The default
15577 @item show debug overload
15578 Displays the current state of displaying @value{GDBN} C@t{++} overload
15580 @cindex packets, reporting on stdout
15581 @cindex serial connections, debugging
15582 @item set debug remote
15583 Turns on or off display of reports on all packets sent back and forth across
15584 the serial line to the remote machine. The info is printed on the
15585 @value{GDBN} standard output stream. The default is off.
15586 @item show debug remote
15587 Displays the state of display of remote packets.
15588 @item set debug serial
15589 Turns on or off display of @value{GDBN} serial debugging info. The
15591 @item show debug serial
15592 Displays the current state of displaying @value{GDBN} serial debugging
15594 @item set debug solib-frv
15595 @cindex FR-V shared-library debugging
15596 Turns on or off debugging messages for FR-V shared-library code.
15597 @item show debug solib-frv
15598 Display the current state of FR-V shared-library code debugging
15600 @item set debug target
15601 @cindex target debugging info
15602 Turns on or off display of @value{GDBN} target debugging info. This info
15603 includes what is going on at the target level of GDB, as it happens. The
15604 default is 0. Set it to 1 to track events, and to 2 to also track the
15605 value of large memory transfers. Changes to this flag do not take effect
15606 until the next time you connect to a target or use the @code{run} command.
15607 @item show debug target
15608 Displays the current state of displaying @value{GDBN} target debugging
15610 @item set debugvarobj
15611 @cindex variable object debugging info
15612 Turns on or off display of @value{GDBN} variable object debugging
15613 info. The default is off.
15614 @item show debugvarobj
15615 Displays the current state of displaying @value{GDBN} variable object
15620 @chapter Canned Sequences of Commands
15622 Aside from breakpoint commands (@pxref{Break Commands, ,Breakpoint
15623 command lists}), @value{GDBN} provides two ways to store sequences of
15624 commands for execution as a unit: user-defined commands and command
15628 * Define:: User-defined commands
15629 * Hooks:: User-defined command hooks
15630 * Command Files:: Command files
15631 * Output:: Commands for controlled output
15635 @section User-defined commands
15637 @cindex user-defined command
15638 A @dfn{user-defined command} is a sequence of @value{GDBN} commands to
15639 which you assign a new name as a command. This is done with the
15640 @code{define} command. User commands may accept up to 10 arguments
15641 separated by whitespace. Arguments are accessed within the user command
15642 via @var{$arg0@dots{}$arg9}. A trivial example:
15646 print $arg0 + $arg1 + $arg2
15650 To execute the command use:
15657 This defines the command @code{adder}, which prints the sum of
15658 its three arguments. Note the arguments are text substitutions, so they may
15659 reference variables, use complex expressions, or even perform inferior
15665 @item define @var{commandname}
15666 Define a command named @var{commandname}. If there is already a command
15667 by that name, you are asked to confirm that you want to redefine it.
15669 The definition of the command is made up of other @value{GDBN} command lines,
15670 which are given following the @code{define} command. The end of these
15671 commands is marked by a line containing @code{end}.
15677 Takes a single argument, which is an expression to evaluate.
15678 It is followed by a series of commands that are executed
15679 only if the expression is true (nonzero).
15680 There can then optionally be a line @code{else}, followed
15681 by a series of commands that are only executed if the expression
15682 was false. The end of the list is marked by a line containing @code{end}.
15686 The syntax is similar to @code{if}: the command takes a single argument,
15687 which is an expression to evaluate, and must be followed by the commands to
15688 execute, one per line, terminated by an @code{end}.
15689 The commands are executed repeatedly as long as the expression
15693 @item document @var{commandname}
15694 Document the user-defined command @var{commandname}, so that it can be
15695 accessed by @code{help}. The command @var{commandname} must already be
15696 defined. This command reads lines of documentation just as @code{define}
15697 reads the lines of the command definition, ending with @code{end}.
15698 After the @code{document} command is finished, @code{help} on command
15699 @var{commandname} displays the documentation you have written.
15701 You may use the @code{document} command again to change the
15702 documentation of a command. Redefining the command with @code{define}
15703 does not change the documentation.
15705 @kindex dont-repeat
15706 @cindex don't repeat command
15708 Used inside a user-defined command, this tells @value{GDBN} that this
15709 command should not be repeated when the user hits @key{RET}
15710 (@pxref{Command Syntax, repeat last command}).
15712 @kindex help user-defined
15713 @item help user-defined
15714 List all user-defined commands, with the first line of the documentation
15719 @itemx show user @var{commandname}
15720 Display the @value{GDBN} commands used to define @var{commandname} (but
15721 not its documentation). If no @var{commandname} is given, display the
15722 definitions for all user-defined commands.
15724 @cindex infinite recusrion in user-defined commands
15725 @kindex show max-user-call-depth
15726 @kindex set max-user-call-depth
15727 @item show max-user-call-depth
15728 @itemx set max-user-call-depth
15729 The value of @code{max-user-call-depth} controls how many recursion
15730 levels are allowed in user-defined commands before GDB suspects an
15731 infinite recursion and aborts the command.
15735 When user-defined commands are executed, the
15736 commands of the definition are not printed. An error in any command
15737 stops execution of the user-defined command.
15739 If used interactively, commands that would ask for confirmation proceed
15740 without asking when used inside a user-defined command. Many @value{GDBN}
15741 commands that normally print messages to say what they are doing omit the
15742 messages when used in a user-defined command.
15745 @section User-defined command hooks
15746 @cindex command hooks
15747 @cindex hooks, for commands
15748 @cindex hooks, pre-command
15751 You may define @dfn{hooks}, which are a special kind of user-defined
15752 command. Whenever you run the command @samp{foo}, if the user-defined
15753 command @samp{hook-foo} exists, it is executed (with no arguments)
15754 before that command.
15756 @cindex hooks, post-command
15758 A hook may also be defined which is run after the command you executed.
15759 Whenever you run the command @samp{foo}, if the user-defined command
15760 @samp{hookpost-foo} exists, it is executed (with no arguments) after
15761 that command. Post-execution hooks may exist simultaneously with
15762 pre-execution hooks, for the same command.
15764 It is valid for a hook to call the command which it hooks. If this
15765 occurs, the hook is not re-executed, thereby avoiding infinite recursion.
15767 @c It would be nice if hookpost could be passed a parameter indicating
15768 @c if the command it hooks executed properly or not. FIXME!
15770 @kindex stop@r{, a pseudo-command}
15771 In addition, a pseudo-command, @samp{stop} exists. Defining
15772 (@samp{hook-stop}) makes the associated commands execute every time
15773 execution stops in your program: before breakpoint commands are run,
15774 displays are printed, or the stack frame is printed.
15776 For example, to ignore @code{SIGALRM} signals while
15777 single-stepping, but treat them normally during normal execution,
15782 handle SIGALRM nopass
15786 handle SIGALRM pass
15789 define hook-continue
15790 handle SIGLARM pass
15794 As a further example, to hook at the begining and end of the @code{echo}
15795 command, and to add extra text to the beginning and end of the message,
15803 define hookpost-echo
15807 (@value{GDBP}) echo Hello World
15808 <<<---Hello World--->>>
15813 You can define a hook for any single-word command in @value{GDBN}, but
15814 not for command aliases; you should define a hook for the basic command
15815 name, e.g. @code{backtrace} rather than @code{bt}.
15816 @c FIXME! So how does Joe User discover whether a command is an alias
15818 If an error occurs during the execution of your hook, execution of
15819 @value{GDBN} commands stops and @value{GDBN} issues a prompt
15820 (before the command that you actually typed had a chance to run).
15822 If you try to define a hook which does not match any known command, you
15823 get a warning from the @code{define} command.
15825 @node Command Files
15826 @section Command files
15828 @cindex command files
15829 A command file for @value{GDBN} is a text file made of lines that are
15830 @value{GDBN} commands. Comments (lines starting with @kbd{#}) may
15831 also be included. An empty line in a command file does nothing; it
15832 does not mean to repeat the last command, as it would from the
15835 You can request the execution of a command file with the @code{source}
15840 @item source @var{filename}
15841 Execute the command file @var{filename}.
15844 The lines in a command file are executed sequentially. They are not
15845 printed as they are executed. An error in any command terminates
15846 execution of the command file and control is returned to the console.
15848 Commands that would ask for confirmation if used interactively proceed
15849 without asking when used in a command file. Many @value{GDBN} commands that
15850 normally print messages to say what they are doing omit the messages
15851 when called from command files.
15853 @value{GDBN} also accepts command input from standard input. In this
15854 mode, normal output goes to standard output and error output goes to
15855 standard error. Errors in a command file supplied on standard input do
15856 not terminate execution of the command file---execution continues with
15860 gdb < cmds > log 2>&1
15863 (The syntax above will vary depending on the shell used.) This example
15864 will execute commands from the file @file{cmds}. All output and errors
15865 would be directed to @file{log}.
15868 @section Commands for controlled output
15870 During the execution of a command file or a user-defined command, normal
15871 @value{GDBN} output is suppressed; the only output that appears is what is
15872 explicitly printed by the commands in the definition. This section
15873 describes three commands useful for generating exactly the output you
15878 @item echo @var{text}
15879 @c I do not consider backslash-space a standard C escape sequence
15880 @c because it is not in ANSI.
15881 Print @var{text}. Nonprinting characters can be included in
15882 @var{text} using C escape sequences, such as @samp{\n} to print a
15883 newline. @strong{No newline is printed unless you specify one.}
15884 In addition to the standard C escape sequences, a backslash followed
15885 by a space stands for a space. This is useful for displaying a
15886 string with spaces at the beginning or the end, since leading and
15887 trailing spaces are otherwise trimmed from all arguments.
15888 To print @samp{@w{ }and foo =@w{ }}, use the command
15889 @samp{echo \@w{ }and foo = \@w{ }}.
15891 A backslash at the end of @var{text} can be used, as in C, to continue
15892 the command onto subsequent lines. For example,
15895 echo This is some text\n\
15896 which is continued\n\
15897 onto several lines.\n
15900 produces the same output as
15903 echo This is some text\n
15904 echo which is continued\n
15905 echo onto several lines.\n
15909 @item output @var{expression}
15910 Print the value of @var{expression} and nothing but that value: no
15911 newlines, no @samp{$@var{nn} = }. The value is not entered in the
15912 value history either. @xref{Expressions, ,Expressions}, for more information
15915 @item output/@var{fmt} @var{expression}
15916 Print the value of @var{expression} in format @var{fmt}. You can use
15917 the same formats as for @code{print}. @xref{Output Formats,,Output
15918 formats}, for more information.
15921 @item printf @var{string}, @var{expressions}@dots{}
15922 Print the values of the @var{expressions} under the control of
15923 @var{string}. The @var{expressions} are separated by commas and may be
15924 either numbers or pointers. Their values are printed as specified by
15925 @var{string}, exactly as if your program were to execute the C
15927 @c FIXME: the above implies that at least all ANSI C formats are
15928 @c supported, but it isn't true: %E and %G don't work (or so it seems).
15929 @c Either this is a bug, or the manual should document what formats are
15933 printf (@var{string}, @var{expressions}@dots{});
15936 For example, you can print two values in hex like this:
15939 printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo
15942 The only backslash-escape sequences that you can use in the format
15943 string are the simple ones that consist of backslash followed by a
15948 @chapter Command Interpreters
15949 @cindex command interpreters
15951 @value{GDBN} supports multiple command interpreters, and some command
15952 infrastructure to allow users or user interface writers to switch
15953 between interpreters or run commands in other interpreters.
15955 @value{GDBN} currently supports two command interpreters, the console
15956 interpreter (sometimes called the command-line interpreter or @sc{cli})
15957 and the machine interface interpreter (or @sc{gdb/mi}). This manual
15958 describes both of these interfaces in great detail.
15960 By default, @value{GDBN} will start with the console interpreter.
15961 However, the user may choose to start @value{GDBN} with another
15962 interpreter by specifying the @option{-i} or @option{--interpreter}
15963 startup options. Defined interpreters include:
15967 @cindex console interpreter
15968 The traditional console or command-line interpreter. This is the most often
15969 used interpreter with @value{GDBN}. With no interpreter specified at runtime,
15970 @value{GDBN} will use this interpreter.
15973 @cindex mi interpreter
15974 The newest @sc{gdb/mi} interface (currently @code{mi2}). Used primarily
15975 by programs wishing to use @value{GDBN} as a backend for a debugger GUI
15976 or an IDE. For more information, see @ref{GDB/MI, ,The @sc{gdb/mi}
15980 @cindex mi2 interpreter
15981 The current @sc{gdb/mi} interface.
15984 @cindex mi1 interpreter
15985 The @sc{gdb/mi} interface included in @value{GDBN} 5.1, 5.2, and 5.3.
15989 @cindex invoke another interpreter
15990 The interpreter being used by @value{GDBN} may not be dynamically
15991 switched at runtime. Although possible, this could lead to a very
15992 precarious situation. Consider an IDE using @sc{gdb/mi}. If a user
15993 enters the command "interpreter-set console" in a console view,
15994 @value{GDBN} would switch to using the console interpreter, rendering
15995 the IDE inoperable!
15997 @kindex interpreter-exec
15998 Although you may only choose a single interpreter at startup, you may execute
15999 commands in any interpreter from the current interpreter using the appropriate
16000 command. If you are running the console interpreter, simply use the
16001 @code{interpreter-exec} command:
16004 interpreter-exec mi "-data-list-register-names"
16007 @sc{gdb/mi} has a similar command, although it is only available in versions of
16008 @value{GDBN} which support @sc{gdb/mi} version 2 (or greater).
16011 @chapter @value{GDBN} Text User Interface
16013 @cindex Text User Interface
16016 * TUI Overview:: TUI overview
16017 * TUI Keys:: TUI key bindings
16018 * TUI Single Key Mode:: TUI single key mode
16019 * TUI Commands:: TUI specific commands
16020 * TUI Configuration:: TUI configuration variables
16023 The @value{GDBN} Text User Interface, TUI in short, is a terminal
16024 interface which uses the @code{curses} library to show the source
16025 file, the assembly output, the program registers and @value{GDBN}
16026 commands in separate text windows.
16028 The TUI is enabled by invoking @value{GDBN} using either
16030 @samp{gdbtui} or @samp{gdb -tui}.
16033 @section TUI overview
16035 The TUI has two display modes that can be switched while
16040 A curses (or TUI) mode in which it displays several text
16041 windows on the terminal.
16044 A standard mode which corresponds to the @value{GDBN} configured without
16048 In the TUI mode, @value{GDBN} can display several text window
16053 This window is the @value{GDBN} command window with the @value{GDBN}
16054 prompt and the @value{GDBN} outputs. The @value{GDBN} input is still
16055 managed using readline but through the TUI. The @emph{command}
16056 window is always visible.
16059 The source window shows the source file of the program. The current
16060 line as well as active breakpoints are displayed in this window.
16063 The assembly window shows the disassembly output of the program.
16066 This window shows the processor registers. It detects when
16067 a register is changed and when this is the case, registers that have
16068 changed are highlighted.
16072 The source and assembly windows show the current program position
16073 by highlighting the current line and marking them with the @samp{>} marker.
16074 Breakpoints are also indicated with two markers. A first one
16075 indicates the breakpoint type:
16079 Breakpoint which was hit at least once.
16082 Breakpoint which was never hit.
16085 Hardware breakpoint which was hit at least once.
16088 Hardware breakpoint which was never hit.
16092 The second marker indicates whether the breakpoint is enabled or not:
16096 Breakpoint is enabled.
16099 Breakpoint is disabled.
16103 The source, assembly and register windows are attached to the thread
16104 and the frame position. They are updated when the current thread
16105 changes, when the frame changes or when the program counter changes.
16106 These three windows are arranged by the TUI according to several
16107 layouts. The layout defines which of these three windows are visible.
16108 The following layouts are available:
16118 source and assembly
16121 source and registers
16124 assembly and registers
16128 On top of the command window a status line gives various information
16129 concerning the current process begin debugged. The status line is
16130 updated when the information it shows changes. The following fields
16135 Indicates the current gdb target
16136 (@pxref{Targets, ,Specifying a Debugging Target}).
16139 Gives information about the current process or thread number.
16140 When no process is being debugged, this field is set to @code{No process}.
16143 Gives the current function name for the selected frame.
16144 The name is demangled if demangling is turned on (@pxref{Print Settings}).
16145 When there is no symbol corresponding to the current program counter
16146 the string @code{??} is displayed.
16149 Indicates the current line number for the selected frame.
16150 When the current line number is not known the string @code{??} is displayed.
16153 Indicates the current program counter address.
16158 @section TUI Key Bindings
16159 @cindex TUI key bindings
16161 The TUI installs several key bindings in the readline keymaps
16162 (@pxref{Command Line Editing}).
16163 They allow to leave or enter in the TUI mode or they operate
16164 directly on the TUI layout and windows. The TUI also provides
16165 a @emph{SingleKey} keymap which binds several keys directly to
16166 @value{GDBN} commands. The following key bindings
16167 are installed for both TUI mode and the @value{GDBN} standard mode.
16176 Enter or leave the TUI mode. When the TUI mode is left,
16177 the curses window management is left and @value{GDBN} operates using
16178 its standard mode writing on the terminal directly. When the TUI
16179 mode is entered, the control is given back to the curses windows.
16180 The screen is then refreshed.
16184 Use a TUI layout with only one window. The layout will
16185 either be @samp{source} or @samp{assembly}. When the TUI mode
16186 is not active, it will switch to the TUI mode.
16188 Think of this key binding as the Emacs @kbd{C-x 1} binding.
16192 Use a TUI layout with at least two windows. When the current
16193 layout shows already two windows, a next layout with two windows is used.
16194 When a new layout is chosen, one window will always be common to the
16195 previous layout and the new one.
16197 Think of it as the Emacs @kbd{C-x 2} binding.
16201 Change the active window. The TUI associates several key bindings
16202 (like scrolling and arrow keys) to the active window. This command
16203 gives the focus to the next TUI window.
16205 Think of it as the Emacs @kbd{C-x o} binding.
16209 Use the TUI @emph{SingleKey} keymap that binds single key to gdb commands
16210 (@pxref{TUI Single Key Mode}).
16214 The following key bindings are handled only by the TUI mode:
16219 Scroll the active window one page up.
16223 Scroll the active window one page down.
16227 Scroll the active window one line up.
16231 Scroll the active window one line down.
16235 Scroll the active window one column left.
16239 Scroll the active window one column right.
16243 Refresh the screen.
16247 In the TUI mode, the arrow keys are used by the active window
16248 for scrolling. This means they are available for readline when the
16249 active window is the command window. When the command window
16250 does not have the focus, it is necessary to use other readline
16251 key bindings such as @key{C-p}, @key{C-n}, @key{C-b} and @key{C-f}.
16253 @node TUI Single Key Mode
16254 @section TUI Single Key Mode
16255 @cindex TUI single key mode
16257 The TUI provides a @emph{SingleKey} mode in which it installs a particular
16258 key binding in the readline keymaps to connect single keys to
16262 @kindex c @r{(SingleKey TUI key)}
16266 @kindex d @r{(SingleKey TUI key)}
16270 @kindex f @r{(SingleKey TUI key)}
16274 @kindex n @r{(SingleKey TUI key)}
16278 @kindex q @r{(SingleKey TUI key)}
16280 exit the @emph{SingleKey} mode.
16282 @kindex r @r{(SingleKey TUI key)}
16286 @kindex s @r{(SingleKey TUI key)}
16290 @kindex u @r{(SingleKey TUI key)}
16294 @kindex v @r{(SingleKey TUI key)}
16298 @kindex w @r{(SingleKey TUI key)}
16304 Other keys temporarily switch to the @value{GDBN} command prompt.
16305 The key that was pressed is inserted in the editing buffer so that
16306 it is possible to type most @value{GDBN} commands without interaction
16307 with the TUI @emph{SingleKey} mode. Once the command is entered the TUI
16308 @emph{SingleKey} mode is restored. The only way to permanently leave
16309 this mode is by hitting @key{q} or @samp{@key{C-x} @key{s}}.
16313 @section TUI specific commands
16314 @cindex TUI commands
16316 The TUI has specific commands to control the text windows.
16317 These commands are always available, that is they do not depend on
16318 the current terminal mode in which @value{GDBN} runs. When @value{GDBN}
16319 is in the standard mode, using these commands will automatically switch
16325 List and give the size of all displayed windows.
16329 Display the next layout.
16332 Display the previous layout.
16335 Display the source window only.
16338 Display the assembly window only.
16341 Display the source and assembly window.
16344 Display the register window together with the source or assembly window.
16346 @item focus next | prev | src | asm | regs | split
16348 Set the focus to the named window.
16349 This command allows to change the active window so that scrolling keys
16350 can be affected to another window.
16354 Refresh the screen. This is similar to using @key{C-L} key.
16356 @item tui reg float
16358 Show the floating point registers in the register window.
16360 @item tui reg general
16361 Show the general registers in the register window.
16364 Show the next register group. The list of register groups as well as
16365 their order is target specific. The predefined register groups are the
16366 following: @code{general}, @code{float}, @code{system}, @code{vector},
16367 @code{all}, @code{save}, @code{restore}.
16369 @item tui reg system
16370 Show the system registers in the register window.
16374 Update the source window and the current execution point.
16376 @item winheight @var{name} +@var{count}
16377 @itemx winheight @var{name} -@var{count}
16379 Change the height of the window @var{name} by @var{count}
16380 lines. Positive counts increase the height, while negative counts
16384 @kindex tabset @var{nchars}
16385 Set the width of tab stops to be @var{nchars} characters.
16389 @node TUI Configuration
16390 @section TUI configuration variables
16391 @cindex TUI configuration variables
16393 The TUI has several configuration variables that control the
16394 appearance of windows on the terminal.
16397 @item set tui border-kind @var{kind}
16398 @kindex set tui border-kind
16399 Select the border appearance for the source, assembly and register windows.
16400 The possible values are the following:
16403 Use a space character to draw the border.
16406 Use ascii characters + - and | to draw the border.
16409 Use the Alternate Character Set to draw the border. The border is
16410 drawn using character line graphics if the terminal supports them.
16414 @item set tui active-border-mode @var{mode}
16415 @kindex set tui active-border-mode
16416 Select the attributes to display the border of the active window.
16417 The possible values are @code{normal}, @code{standout}, @code{reverse},
16418 @code{half}, @code{half-standout}, @code{bold} and @code{bold-standout}.
16420 @item set tui border-mode @var{mode}
16421 @kindex set tui border-mode
16422 Select the attributes to display the border of other windows.
16423 The @var{mode} can be one of the following:
16426 Use normal attributes to display the border.
16432 Use reverse video mode.
16435 Use half bright mode.
16437 @item half-standout
16438 Use half bright and standout mode.
16441 Use extra bright or bold mode.
16443 @item bold-standout
16444 Use extra bright or bold and standout mode.
16451 @chapter Using @value{GDBN} under @sc{gnu} Emacs
16454 @cindex @sc{gnu} Emacs
16455 A special interface allows you to use @sc{gnu} Emacs to view (and
16456 edit) the source files for the program you are debugging with
16459 To use this interface, use the command @kbd{M-x gdb} in Emacs. Give the
16460 executable file you want to debug as an argument. This command starts
16461 @value{GDBN} as a subprocess of Emacs, with input and output through a newly
16462 created Emacs buffer.
16463 @c (Do not use the @code{-tui} option to run @value{GDBN} from Emacs.)
16465 Using @value{GDBN} under Emacs is just like using @value{GDBN} normally except for two
16470 All ``terminal'' input and output goes through the Emacs buffer.
16473 This applies both to @value{GDBN} commands and their output, and to the input
16474 and output done by the program you are debugging.
16476 This is useful because it means that you can copy the text of previous
16477 commands and input them again; you can even use parts of the output
16480 All the facilities of Emacs' Shell mode are available for interacting
16481 with your program. In particular, you can send signals the usual
16482 way---for example, @kbd{C-c C-c} for an interrupt, @kbd{C-c C-z} for a
16487 @value{GDBN} displays source code through Emacs.
16490 Each time @value{GDBN} displays a stack frame, Emacs automatically finds the
16491 source file for that frame and puts an arrow (@samp{=>}) at the
16492 left margin of the current line. Emacs uses a separate buffer for
16493 source display, and splits the screen to show both your @value{GDBN} session
16496 Explicit @value{GDBN} @code{list} or search commands still produce output as
16497 usual, but you probably have no reason to use them from Emacs.
16499 If you specify an absolute file name when prompted for the @kbd{M-x
16500 gdb} argument, then Emacs sets your current working directory to where
16501 your program resides. If you only specify the file name, then Emacs
16502 sets your current working directory to to the directory associated
16503 with the previous buffer. In this case, @value{GDBN} may find your
16504 program by searching your environment's @code{PATH} variable, but on
16505 some operating systems it might not find the source. So, although the
16506 @value{GDBN} input and output session proceeds normally, the auxiliary
16507 buffer does not display the current source and line of execution.
16509 The initial working directory of @value{GDBN} is printed on the top
16510 line of the @value{GDBN} I/O buffer and this serves as a default for
16511 the commands that specify files for @value{GDBN} to operate
16512 on. @xref{Files, ,Commands to specify files}.
16514 By default, @kbd{M-x gdb} calls the program called @file{gdb}. If you
16515 need to call @value{GDBN} by a different name (for example, if you
16516 keep several configurations around, with different names) you can
16517 customize the Emacs variable @code{gud-gdb-command-name} to run the
16520 In the @value{GDBN} I/O buffer, you can use these special Emacs commands in
16521 addition to the standard Shell mode commands:
16525 Describe the features of Emacs' @value{GDBN} Mode.
16528 Execute to another source line, like the @value{GDBN} @code{step} command; also
16529 update the display window to show the current file and location.
16532 Execute to next source line in this function, skipping all function
16533 calls, like the @value{GDBN} @code{next} command. Then update the display window
16534 to show the current file and location.
16537 Execute one instruction, like the @value{GDBN} @code{stepi} command; update
16538 display window accordingly.
16541 Execute until exit from the selected stack frame, like the @value{GDBN}
16542 @code{finish} command.
16545 Continue execution of your program, like the @value{GDBN} @code{continue}
16549 Go up the number of frames indicated by the numeric argument
16550 (@pxref{Arguments, , Numeric Arguments, Emacs, The @sc{gnu} Emacs Manual}),
16551 like the @value{GDBN} @code{up} command.
16554 Go down the number of frames indicated by the numeric argument, like the
16555 @value{GDBN} @code{down} command.
16558 In any source file, the Emacs command @kbd{C-x SPC} (@code{gud-break})
16559 tells @value{GDBN} to set a breakpoint on the source line point is on.
16561 If you type @kbd{M-x speedbar}, then Emacs displays a separate frame which
16562 shows a backtrace when the @value{GDBN} I/O buffer is current. Move
16563 point to any frame in the stack and type @key{RET} to make it become the
16564 current frame and display the associated source in the source buffer.
16565 Alternatively, click @kbd{Mouse-2} to make the selected frame become the
16568 If you accidentally delete the source-display buffer, an easy way to get
16569 it back is to type the command @code{f} in the @value{GDBN} buffer, to
16570 request a frame display; when you run under Emacs, this recreates
16571 the source buffer if necessary to show you the context of the current
16574 The source files displayed in Emacs are in ordinary Emacs buffers
16575 which are visiting the source files in the usual way. You can edit
16576 the files with these buffers if you wish; but keep in mind that @value{GDBN}
16577 communicates with Emacs in terms of line numbers. If you add or
16578 delete lines from the text, the line numbers that @value{GDBN} knows cease
16579 to correspond properly with the code.
16581 The description given here is for GNU Emacs version 21.3 and a more
16582 detailed description of its interaction with @value{GDBN} is given in
16583 the Emacs manual (@pxref{Debuggers,,, Emacs, The @sc{gnu} Emacs Manual}).
16585 @c The following dropped because Epoch is nonstandard. Reactivate
16586 @c if/when v19 does something similar. ---doc@cygnus.com 19dec1990
16588 @kindex Emacs Epoch environment
16592 Version 18 of @sc{gnu} Emacs has a built-in window system
16593 called the @code{epoch}
16594 environment. Users of this environment can use a new command,
16595 @code{inspect} which performs identically to @code{print} except that
16596 each value is printed in its own window.
16601 @chapter The @sc{gdb/mi} Interface
16603 @unnumberedsec Function and Purpose
16605 @cindex @sc{gdb/mi}, its purpose
16606 @sc{gdb/mi} is a line based machine oriented text interface to
16607 @value{GDBN} and is activated by specifying using the
16608 @option{--interpreter} command line option (@pxref{Mode Options}). It
16609 is specifically intended to support the development of systems which
16610 use the debugger as just one small component of a larger system.
16612 This chapter is a specification of the @sc{gdb/mi} interface. It is written
16613 in the form of a reference manual.
16615 Note that @sc{gdb/mi} is still under construction, so some of the
16616 features described below are incomplete and subject to change.
16618 @unnumberedsec Notation and Terminology
16620 @cindex notational conventions, for @sc{gdb/mi}
16621 This chapter uses the following notation:
16625 @code{|} separates two alternatives.
16628 @code{[ @var{something} ]} indicates that @var{something} is optional:
16629 it may or may not be given.
16632 @code{( @var{group} )*} means that @var{group} inside the parentheses
16633 may repeat zero or more times.
16636 @code{( @var{group} )+} means that @var{group} inside the parentheses
16637 may repeat one or more times.
16640 @code{"@var{string}"} means a literal @var{string}.
16644 @heading Dependencies
16647 @heading Acknowledgments
16649 In alphabetic order: Andrew Cagney, Fernando Nasser, Stan Shebs and
16653 * GDB/MI Command Syntax::
16654 * GDB/MI Compatibility with CLI::
16655 * GDB/MI Output Records::
16656 * GDB/MI Command Description Format::
16657 * GDB/MI Breakpoint Table Commands::
16658 * GDB/MI Data Manipulation::
16659 * GDB/MI Program Control::
16660 * GDB/MI Miscellaneous Commands::
16662 * GDB/MI Kod Commands::
16663 * GDB/MI Memory Overlay Commands::
16664 * GDB/MI Signal Handling Commands::
16666 * GDB/MI Stack Manipulation::
16667 * GDB/MI Symbol Query::
16668 * GDB/MI Target Manipulation::
16669 * GDB/MI Thread Commands::
16670 * GDB/MI Tracepoint Commands::
16671 * GDB/MI Variable Objects::
16674 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
16675 @node GDB/MI Command Syntax
16676 @section @sc{gdb/mi} Command Syntax
16679 * GDB/MI Input Syntax::
16680 * GDB/MI Output Syntax::
16681 * GDB/MI Simple Examples::
16684 @node GDB/MI Input Syntax
16685 @subsection @sc{gdb/mi} Input Syntax
16687 @cindex input syntax for @sc{gdb/mi}
16688 @cindex @sc{gdb/mi}, input syntax
16690 @item @var{command} @expansion{}
16691 @code{@var{cli-command} | @var{mi-command}}
16693 @item @var{cli-command} @expansion{}
16694 @code{[ @var{token} ] @var{cli-command} @var{nl}}, where
16695 @var{cli-command} is any existing @value{GDBN} CLI command.
16697 @item @var{mi-command} @expansion{}
16698 @code{[ @var{token} ] "-" @var{operation} ( " " @var{option} )*
16699 @code{[} " --" @code{]} ( " " @var{parameter} )* @var{nl}}
16701 @item @var{token} @expansion{}
16702 "any sequence of digits"
16704 @item @var{option} @expansion{}
16705 @code{"-" @var{parameter} [ " " @var{parameter} ]}
16707 @item @var{parameter} @expansion{}
16708 @code{@var{non-blank-sequence} | @var{c-string}}
16710 @item @var{operation} @expansion{}
16711 @emph{any of the operations described in this chapter}
16713 @item @var{non-blank-sequence} @expansion{}
16714 @emph{anything, provided it doesn't contain special characters such as
16715 "-", @var{nl}, """ and of course " "}
16717 @item @var{c-string} @expansion{}
16718 @code{""" @var{seven-bit-iso-c-string-content} """}
16720 @item @var{nl} @expansion{}
16729 The CLI commands are still handled by the @sc{mi} interpreter; their
16730 output is described below.
16733 The @code{@var{token}}, when present, is passed back when the command
16737 Some @sc{mi} commands accept optional arguments as part of the parameter
16738 list. Each option is identified by a leading @samp{-} (dash) and may be
16739 followed by an optional argument parameter. Options occur first in the
16740 parameter list and can be delimited from normal parameters using
16741 @samp{--} (this is useful when some parameters begin with a dash).
16748 We want easy access to the existing CLI syntax (for debugging).
16751 We want it to be easy to spot a @sc{mi} operation.
16754 @node GDB/MI Output Syntax
16755 @subsection @sc{gdb/mi} Output Syntax
16757 @cindex output syntax of @sc{gdb/mi}
16758 @cindex @sc{gdb/mi}, output syntax
16759 The output from @sc{gdb/mi} consists of zero or more out-of-band records
16760 followed, optionally, by a single result record. This result record
16761 is for the most recent command. The sequence of output records is
16762 terminated by @samp{(@value{GDBP})}.
16764 If an input command was prefixed with a @code{@var{token}} then the
16765 corresponding output for that command will also be prefixed by that same
16769 @item @var{output} @expansion{}
16770 @code{( @var{out-of-band-record} )* [ @var{result-record} ] "(@value{GDBP})" @var{nl}}
16772 @item @var{result-record} @expansion{}
16773 @code{ [ @var{token} ] "^" @var{result-class} ( "," @var{result} )* @var{nl}}
16775 @item @var{out-of-band-record} @expansion{}
16776 @code{@var{async-record} | @var{stream-record}}
16778 @item @var{async-record} @expansion{}
16779 @code{@var{exec-async-output} | @var{status-async-output} | @var{notify-async-output}}
16781 @item @var{exec-async-output} @expansion{}
16782 @code{[ @var{token} ] "*" @var{async-output}}
16784 @item @var{status-async-output} @expansion{}
16785 @code{[ @var{token} ] "+" @var{async-output}}
16787 @item @var{notify-async-output} @expansion{}
16788 @code{[ @var{token} ] "=" @var{async-output}}
16790 @item @var{async-output} @expansion{}
16791 @code{@var{async-class} ( "," @var{result} )* @var{nl}}
16793 @item @var{result-class} @expansion{}
16794 @code{"done" | "running" | "connected" | "error" | "exit"}
16796 @item @var{async-class} @expansion{}
16797 @code{"stopped" | @var{others}} (where @var{others} will be added
16798 depending on the needs---this is still in development).
16800 @item @var{result} @expansion{}
16801 @code{ @var{variable} "=" @var{value}}
16803 @item @var{variable} @expansion{}
16804 @code{ @var{string} }
16806 @item @var{value} @expansion{}
16807 @code{ @var{const} | @var{tuple} | @var{list} }
16809 @item @var{const} @expansion{}
16810 @code{@var{c-string}}
16812 @item @var{tuple} @expansion{}
16813 @code{ "@{@}" | "@{" @var{result} ( "," @var{result} )* "@}" }
16815 @item @var{list} @expansion{}
16816 @code{ "[]" | "[" @var{value} ( "," @var{value} )* "]" | "["
16817 @var{result} ( "," @var{result} )* "]" }
16819 @item @var{stream-record} @expansion{}
16820 @code{@var{console-stream-output} | @var{target-stream-output} | @var{log-stream-output}}
16822 @item @var{console-stream-output} @expansion{}
16823 @code{"~" @var{c-string}}
16825 @item @var{target-stream-output} @expansion{}
16826 @code{"@@" @var{c-string}}
16828 @item @var{log-stream-output} @expansion{}
16829 @code{"&" @var{c-string}}
16831 @item @var{nl} @expansion{}
16834 @item @var{token} @expansion{}
16835 @emph{any sequence of digits}.
16843 All output sequences end in a single line containing a period.
16846 The @code{@var{token}} is from the corresponding request. If an execution
16847 command is interrupted by the @samp{-exec-interrupt} command, the
16848 @var{token} associated with the @samp{*stopped} message is the one of the
16849 original execution command, not the one of the interrupt command.
16852 @cindex status output in @sc{gdb/mi}
16853 @var{status-async-output} contains on-going status information about the
16854 progress of a slow operation. It can be discarded. All status output is
16855 prefixed by @samp{+}.
16858 @cindex async output in @sc{gdb/mi}
16859 @var{exec-async-output} contains asynchronous state change on the target
16860 (stopped, started, disappeared). All async output is prefixed by
16864 @cindex notify output in @sc{gdb/mi}
16865 @var{notify-async-output} contains supplementary information that the
16866 client should handle (e.g., a new breakpoint information). All notify
16867 output is prefixed by @samp{=}.
16870 @cindex console output in @sc{gdb/mi}
16871 @var{console-stream-output} is output that should be displayed as is in the
16872 console. It is the textual response to a CLI command. All the console
16873 output is prefixed by @samp{~}.
16876 @cindex target output in @sc{gdb/mi}
16877 @var{target-stream-output} is the output produced by the target program.
16878 All the target output is prefixed by @samp{@@}.
16881 @cindex log output in @sc{gdb/mi}
16882 @var{log-stream-output} is output text coming from @value{GDBN}'s internals, for
16883 instance messages that should be displayed as part of an error log. All
16884 the log output is prefixed by @samp{&}.
16887 @cindex list output in @sc{gdb/mi}
16888 New @sc{gdb/mi} commands should only output @var{lists} containing
16894 @xref{GDB/MI Stream Records, , @sc{gdb/mi} Stream Records}, for more
16895 details about the various output records.
16897 @node GDB/MI Simple Examples
16898 @subsection Simple Examples of @sc{gdb/mi} Interaction
16899 @cindex @sc{gdb/mi}, simple examples
16901 This subsection presents several simple examples of interaction using
16902 the @sc{gdb/mi} interface. In these examples, @samp{->} means that the
16903 following line is passed to @sc{gdb/mi} as input, while @samp{<-} means
16904 the output received from @sc{gdb/mi}.
16906 @subsubheading Target Stop
16907 @c Ummm... There is no "-stop" command. This assumes async, no?
16908 Here's an example of stopping the inferior process:
16919 <- *stop,reason="stop",address="0x123",source="a.c:123"
16923 @subsubheading Simple CLI Command
16925 Here's an example of a simple CLI command being passed through
16926 @sc{gdb/mi} and on to the CLI.
16936 @subsubheading Command With Side Effects
16939 -> -symbol-file xyz.exe
16940 <- *breakpoint,nr="3",address="0x123",source="a.c:123"
16944 @subsubheading A Bad Command
16946 Here's what happens if you pass a non-existent command:
16950 <- ^error,msg="Undefined MI command: rubbish"
16954 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
16955 @node GDB/MI Compatibility with CLI
16956 @section @sc{gdb/mi} Compatibility with CLI
16958 @cindex compatibility, @sc{gdb/mi} and CLI
16959 @cindex @sc{gdb/mi}, compatibility with CLI
16960 To help users familiar with @value{GDBN}'s existing CLI interface, @sc{gdb/mi}
16961 accepts existing CLI commands. As specified by the syntax, such
16962 commands can be directly entered into the @sc{gdb/mi} interface and @value{GDBN} will
16965 This mechanism is provided as an aid to developers of @sc{gdb/mi}
16966 clients and not as a reliable interface into the CLI. Since the command
16967 is being interpreteted in an environment that assumes @sc{gdb/mi}
16968 behaviour, the exact output of such commands is likely to end up being
16969 an un-supported hybrid of @sc{gdb/mi} and CLI output.
16971 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
16972 @node GDB/MI Output Records
16973 @section @sc{gdb/mi} Output Records
16976 * GDB/MI Result Records::
16977 * GDB/MI Stream Records::
16978 * GDB/MI Out-of-band Records::
16981 @node GDB/MI Result Records
16982 @subsection @sc{gdb/mi} Result Records
16984 @cindex result records in @sc{gdb/mi}
16985 @cindex @sc{gdb/mi}, result records
16986 In addition to a number of out-of-band notifications, the response to a
16987 @sc{gdb/mi} command includes one of the following result indications:
16991 @item "^done" [ "," @var{results} ]
16992 The synchronous operation was successful, @code{@var{results}} are the return
16997 @c Is this one correct? Should it be an out-of-band notification?
16998 The asynchronous operation was successfully started. The target is
17001 @item "^error" "," @var{c-string}
17003 The operation failed. The @code{@var{c-string}} contains the corresponding
17007 @node GDB/MI Stream Records
17008 @subsection @sc{gdb/mi} Stream Records
17010 @cindex @sc{gdb/mi}, stream records
17011 @cindex stream records in @sc{gdb/mi}
17012 @value{GDBN} internally maintains a number of output streams: the console, the
17013 target, and the log. The output intended for each of these streams is
17014 funneled through the @sc{gdb/mi} interface using @dfn{stream records}.
17016 Each stream record begins with a unique @dfn{prefix character} which
17017 identifies its stream (@pxref{GDB/MI Output Syntax, , @sc{gdb/mi} Output
17018 Syntax}). In addition to the prefix, each stream record contains a
17019 @code{@var{string-output}}. This is either raw text (with an implicit new
17020 line) or a quoted C string (which does not contain an implicit newline).
17023 @item "~" @var{string-output}
17024 The console output stream contains text that should be displayed in the
17025 CLI console window. It contains the textual responses to CLI commands.
17027 @item "@@" @var{string-output}
17028 The target output stream contains any textual output from the running
17031 @item "&" @var{string-output}
17032 The log stream contains debugging messages being produced by @value{GDBN}'s
17036 @node GDB/MI Out-of-band Records
17037 @subsection @sc{gdb/mi} Out-of-band Records
17039 @cindex out-of-band records in @sc{gdb/mi}
17040 @cindex @sc{gdb/mi}, out-of-band records
17041 @dfn{Out-of-band} records are used to notify the @sc{gdb/mi} client of
17042 additional changes that have occurred. Those changes can either be a
17043 consequence of @sc{gdb/mi} (e.g., a breakpoint modified) or a result of
17044 target activity (e.g., target stopped).
17046 The following is a preliminary list of possible out-of-band records.
17047 In particular, the @var{exec-async-output} records.
17050 @item *stopped,reason="@var{reason}"
17053 @var{reason} can be one of the following:
17056 @item breakpoint-hit
17057 A breakpoint was reached.
17058 @item watchpoint-trigger
17059 A watchpoint was triggered.
17060 @item read-watchpoint-trigger
17061 A read watchpoint was triggered.
17062 @item access-watchpoint-trigger
17063 An access watchpoint was triggered.
17064 @item function-finished
17065 An -exec-finish or similar CLI command was accomplished.
17066 @item location-reached
17067 An -exec-until or similar CLI command was accomplished.
17068 @item watchpoint-scope
17069 A watchpoint has gone out of scope.
17070 @item end-stepping-range
17071 An -exec-next, -exec-next-instruction, -exec-step, -exec-step-instruction or
17072 similar CLI command was accomplished.
17073 @item exited-signalled
17074 The inferior exited because of a signal.
17076 The inferior exited.
17077 @item exited-normally
17078 The inferior exited normally.
17079 @item signal-received
17080 A signal was received by the inferior.
17084 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
17085 @node GDB/MI Command Description Format
17086 @section @sc{gdb/mi} Command Description Format
17088 The remaining sections describe blocks of commands. Each block of
17089 commands is laid out in a fashion similar to this section.
17091 Note the the line breaks shown in the examples are here only for
17092 readability. They don't appear in the real output.
17093 Also note that the commands with a non-available example (N.A.@:) are
17094 not yet implemented.
17096 @subheading Motivation
17098 The motivation for this collection of commands.
17100 @subheading Introduction
17102 A brief introduction to this collection of commands as a whole.
17104 @subheading Commands
17106 For each command in the block, the following is described:
17108 @subsubheading Synopsis
17111 -command @var{args}@dots{}
17114 @subsubheading Result
17116 @subsubheading @value{GDBN} Command
17118 The corresponding @value{GDBN} CLI command(s), if any.
17120 @subsubheading Example
17122 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
17123 @node GDB/MI Breakpoint Table Commands
17124 @section @sc{gdb/mi} Breakpoint table commands
17126 @cindex breakpoint commands for @sc{gdb/mi}
17127 @cindex @sc{gdb/mi}, breakpoint commands
17128 This section documents @sc{gdb/mi} commands for manipulating
17131 @subheading The @code{-break-after} Command
17132 @findex -break-after
17134 @subsubheading Synopsis
17137 -break-after @var{number} @var{count}
17140 The breakpoint number @var{number} is not in effect until it has been
17141 hit @var{count} times. To see how this is reflected in the output of
17142 the @samp{-break-list} command, see the description of the
17143 @samp{-break-list} command below.
17145 @subsubheading @value{GDBN} Command
17147 The corresponding @value{GDBN} command is @samp{ignore}.
17149 @subsubheading Example
17154 ^done,bkpt=@{number="1",addr="0x000100d0",file="hello.c",line="5"@}
17161 ^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
17162 hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
17163 @{width="14",alignment="-1",col_name="type",colhdr="Type"@},
17164 @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
17165 @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
17166 @{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
17167 @{width="40",alignment="2",col_name="what",colhdr="What"@}],
17168 body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
17169 addr="0x000100d0",func="main",file="hello.c",line="5",times="0",
17175 @subheading The @code{-break-catch} Command
17176 @findex -break-catch
17178 @subheading The @code{-break-commands} Command
17179 @findex -break-commands
17183 @subheading The @code{-break-condition} Command
17184 @findex -break-condition
17186 @subsubheading Synopsis
17189 -break-condition @var{number} @var{expr}
17192 Breakpoint @var{number} will stop the program only if the condition in
17193 @var{expr} is true. The condition becomes part of the
17194 @samp{-break-list} output (see the description of the @samp{-break-list}
17197 @subsubheading @value{GDBN} Command
17199 The corresponding @value{GDBN} command is @samp{condition}.
17201 @subsubheading Example
17205 -break-condition 1 1
17209 ^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
17210 hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
17211 @{width="14",alignment="-1",col_name="type",colhdr="Type"@},
17212 @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
17213 @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
17214 @{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
17215 @{width="40",alignment="2",col_name="what",colhdr="What"@}],
17216 body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
17217 addr="0x000100d0",func="main",file="hello.c",line="5",cond="1",
17218 times="0",ignore="3"@}]@}
17222 @subheading The @code{-break-delete} Command
17223 @findex -break-delete
17225 @subsubheading Synopsis
17228 -break-delete ( @var{breakpoint} )+
17231 Delete the breakpoint(s) whose number(s) are specified in the argument
17232 list. This is obviously reflected in the breakpoint list.
17234 @subsubheading @value{GDBN} command
17236 The corresponding @value{GDBN} command is @samp{delete}.
17238 @subsubheading Example
17246 ^done,BreakpointTable=@{nr_rows="0",nr_cols="6",
17247 hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
17248 @{width="14",alignment="-1",col_name="type",colhdr="Type"@},
17249 @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
17250 @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
17251 @{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
17252 @{width="40",alignment="2",col_name="what",colhdr="What"@}],
17257 @subheading The @code{-break-disable} Command
17258 @findex -break-disable
17260 @subsubheading Synopsis
17263 -break-disable ( @var{breakpoint} )+
17266 Disable the named @var{breakpoint}(s). The field @samp{enabled} in the
17267 break list is now set to @samp{n} for the named @var{breakpoint}(s).
17269 @subsubheading @value{GDBN} Command
17271 The corresponding @value{GDBN} command is @samp{disable}.
17273 @subsubheading Example
17281 ^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
17282 hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
17283 @{width="14",alignment="-1",col_name="type",colhdr="Type"@},
17284 @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
17285 @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
17286 @{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
17287 @{width="40",alignment="2",col_name="what",colhdr="What"@}],
17288 body=[bkpt=@{number="2",type="breakpoint",disp="keep",enabled="n",
17289 addr="0x000100d0",func="main",file="hello.c",line="5",times="0"@}]@}
17293 @subheading The @code{-break-enable} Command
17294 @findex -break-enable
17296 @subsubheading Synopsis
17299 -break-enable ( @var{breakpoint} )+
17302 Enable (previously disabled) @var{breakpoint}(s).
17304 @subsubheading @value{GDBN} Command
17306 The corresponding @value{GDBN} command is @samp{enable}.
17308 @subsubheading Example
17316 ^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
17317 hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
17318 @{width="14",alignment="-1",col_name="type",colhdr="Type"@},
17319 @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
17320 @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
17321 @{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
17322 @{width="40",alignment="2",col_name="what",colhdr="What"@}],
17323 body=[bkpt=@{number="2",type="breakpoint",disp="keep",enabled="y",
17324 addr="0x000100d0",func="main",file="hello.c",line="5",times="0"@}]@}
17328 @subheading The @code{-break-info} Command
17329 @findex -break-info
17331 @subsubheading Synopsis
17334 -break-info @var{breakpoint}
17338 Get information about a single breakpoint.
17340 @subsubheading @value{GDBN} command
17342 The corresponding @value{GDBN} command is @samp{info break @var{breakpoint}}.
17344 @subsubheading Example
17347 @subheading The @code{-break-insert} Command
17348 @findex -break-insert
17350 @subsubheading Synopsis
17353 -break-insert [ -t ] [ -h ] [ -r ]
17354 [ -c @var{condition} ] [ -i @var{ignore-count} ]
17355 [ -p @var{thread} ] [ @var{line} | @var{addr} ]
17359 If specified, @var{line}, can be one of:
17366 @item filename:linenum
17367 @item filename:function
17371 The possible optional parameters of this command are:
17375 Insert a tempoary breakpoint.
17377 Insert a hardware breakpoint.
17378 @item -c @var{condition}
17379 Make the breakpoint conditional on @var{condition}.
17380 @item -i @var{ignore-count}
17381 Initialize the @var{ignore-count}.
17383 Insert a regular breakpoint in all the functions whose names match the
17384 given regular expression. Other flags are not applicable to regular
17388 @subsubheading Result
17390 The result is in the form:
17393 ^done,bkptno="@var{number}",func="@var{funcname}",
17394 file="@var{filename}",line="@var{lineno}"
17398 where @var{number} is the @value{GDBN} number for this breakpoint, @var{funcname}
17399 is the name of the function where the breakpoint was inserted,
17400 @var{filename} is the name of the source file which contains this
17401 function, and @var{lineno} is the source line number within that file.
17403 Note: this format is open to change.
17404 @c An out-of-band breakpoint instead of part of the result?
17406 @subsubheading @value{GDBN} Command
17408 The corresponding @value{GDBN} commands are @samp{break}, @samp{tbreak},
17409 @samp{hbreak}, @samp{thbreak}, and @samp{rbreak}.
17411 @subsubheading Example
17416 ^done,bkpt=@{number="1",addr="0x0001072c",file="recursive2.c",line="4"@}
17418 -break-insert -t foo
17419 ^done,bkpt=@{number="2",addr="0x00010774",file="recursive2.c",line="11"@}
17422 ^done,BreakpointTable=@{nr_rows="2",nr_cols="6",
17423 hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
17424 @{width="14",alignment="-1",col_name="type",colhdr="Type"@},
17425 @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
17426 @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
17427 @{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
17428 @{width="40",alignment="2",col_name="what",colhdr="What"@}],
17429 body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
17430 addr="0x0001072c", func="main",file="recursive2.c",line="4",times="0"@},
17431 bkpt=@{number="2",type="breakpoint",disp="del",enabled="y",
17432 addr="0x00010774",func="foo",file="recursive2.c",line="11",times="0"@}]@}
17434 -break-insert -r foo.*
17435 ~int foo(int, int);
17436 ^done,bkpt=@{number="3",addr="0x00010774",file="recursive2.c",line="11"@}
17440 @subheading The @code{-break-list} Command
17441 @findex -break-list
17443 @subsubheading Synopsis
17449 Displays the list of inserted breakpoints, showing the following fields:
17453 number of the breakpoint
17455 type of the breakpoint: @samp{breakpoint} or @samp{watchpoint}
17457 should the breakpoint be deleted or disabled when it is hit: @samp{keep}
17460 is the breakpoint enabled or no: @samp{y} or @samp{n}
17462 memory location at which the breakpoint is set
17464 logical location of the breakpoint, expressed by function name, file
17467 number of times the breakpoint has been hit
17470 If there are no breakpoints or watchpoints, the @code{BreakpointTable}
17471 @code{body} field is an empty list.
17473 @subsubheading @value{GDBN} Command
17475 The corresponding @value{GDBN} command is @samp{info break}.
17477 @subsubheading Example
17482 ^done,BreakpointTable=@{nr_rows="2",nr_cols="6",
17483 hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
17484 @{width="14",alignment="-1",col_name="type",colhdr="Type"@},
17485 @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
17486 @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
17487 @{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
17488 @{width="40",alignment="2",col_name="what",colhdr="What"@}],
17489 body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
17490 addr="0x000100d0",func="main",file="hello.c",line="5",times="0"@},
17491 bkpt=@{number="2",type="breakpoint",disp="keep",enabled="y",
17492 addr="0x00010114",func="foo",file="hello.c",line="13",times="0"@}]@}
17496 Here's an example of the result when there are no breakpoints:
17501 ^done,BreakpointTable=@{nr_rows="0",nr_cols="6",
17502 hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
17503 @{width="14",alignment="-1",col_name="type",colhdr="Type"@},
17504 @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
17505 @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
17506 @{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
17507 @{width="40",alignment="2",col_name="what",colhdr="What"@}],
17512 @subheading The @code{-break-watch} Command
17513 @findex -break-watch
17515 @subsubheading Synopsis
17518 -break-watch [ -a | -r ]
17521 Create a watchpoint. With the @samp{-a} option it will create an
17522 @dfn{access} watchpoint, i.e. a watchpoint that triggers either on a
17523 read from or on a write to the memory location. With the @samp{-r}
17524 option, the watchpoint created is a @dfn{read} watchpoint, i.e. it will
17525 trigger only when the memory location is accessed for reading. Without
17526 either of the options, the watchpoint created is a regular watchpoint,
17527 i.e. it will trigger when the memory location is accessed for writing.
17528 @xref{Set Watchpoints, , Setting watchpoints}.
17530 Note that @samp{-break-list} will report a single list of watchpoints and
17531 breakpoints inserted.
17533 @subsubheading @value{GDBN} Command
17535 The corresponding @value{GDBN} commands are @samp{watch}, @samp{awatch}, and
17538 @subsubheading Example
17540 Setting a watchpoint on a variable in the @code{main} function:
17545 ^done,wpt=@{number="2",exp="x"@}
17549 ^done,reason="watchpoint-trigger",wpt=@{number="2",exp="x"@},
17550 value=@{old="-268439212",new="55"@},
17551 frame=@{func="main",args=[],file="recursive2.c",
17552 fullname="/home/foo/bar/devo/myproject/recursive2.c",line="5"@}
17556 Setting a watchpoint on a variable local to a function. @value{GDBN} will stop
17557 the program execution twice: first for the variable changing value, then
17558 for the watchpoint going out of scope.
17563 ^done,wpt=@{number="5",exp="C"@}
17567 ^done,reason="watchpoint-trigger",
17568 wpt=@{number="5",exp="C"@},value=@{old="-276895068",new="3"@},
17569 frame=@{func="callee4",args=[],
17570 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
17571 fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13"@}
17575 ^done,reason="watchpoint-scope",wpnum="5",
17576 frame=@{func="callee3",args=[@{name="strarg",
17577 value="0x11940 \"A string argument.\""@}],
17578 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
17579 fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"@}
17583 Listing breakpoints and watchpoints, at different points in the program
17584 execution. Note that once the watchpoint goes out of scope, it is
17590 ^done,wpt=@{number="2",exp="C"@}
17593 ^done,BreakpointTable=@{nr_rows="2",nr_cols="6",
17594 hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
17595 @{width="14",alignment="-1",col_name="type",colhdr="Type"@},
17596 @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
17597 @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
17598 @{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
17599 @{width="40",alignment="2",col_name="what",colhdr="What"@}],
17600 body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
17601 addr="0x00010734",func="callee4",
17602 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8",times="1"@},
17603 bkpt=@{number="2",type="watchpoint",disp="keep",
17604 enabled="y",addr="",what="C",times="0"@}]@}
17608 ^done,reason="watchpoint-trigger",wpt=@{number="2",exp="C"@},
17609 value=@{old="-276895068",new="3"@},
17610 frame=@{func="callee4",args=[],
17611 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
17612 fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13"@}
17615 ^done,BreakpointTable=@{nr_rows="2",nr_cols="6",
17616 hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
17617 @{width="14",alignment="-1",col_name="type",colhdr="Type"@},
17618 @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
17619 @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
17620 @{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
17621 @{width="40",alignment="2",col_name="what",colhdr="What"@}],
17622 body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
17623 addr="0x00010734",func="callee4",
17624 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8",times="1"@},
17625 bkpt=@{number="2",type="watchpoint",disp="keep",
17626 enabled="y",addr="",what="C",times="-5"@}]@}
17630 ^done,reason="watchpoint-scope",wpnum="2",
17631 frame=@{func="callee3",args=[@{name="strarg",
17632 value="0x11940 \"A string argument.\""@}],
17633 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
17634 fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"@}
17637 ^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
17638 hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
17639 @{width="14",alignment="-1",col_name="type",colhdr="Type"@},
17640 @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
17641 @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
17642 @{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
17643 @{width="40",alignment="2",col_name="what",colhdr="What"@}],
17644 body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
17645 addr="0x00010734",func="callee4",
17646 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8",times="1"@}]@}
17650 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
17651 @node GDB/MI Data Manipulation
17652 @section @sc{gdb/mi} Data Manipulation
17654 @cindex data manipulation, in @sc{gdb/mi}
17655 @cindex @sc{gdb/mi}, data manipulation
17656 This section describes the @sc{gdb/mi} commands that manipulate data:
17657 examine memory and registers, evaluate expressions, etc.
17659 @c REMOVED FROM THE INTERFACE.
17660 @c @subheading -data-assign
17661 @c Change the value of a program variable. Plenty of side effects.
17662 @c @subsubheading GDB command
17664 @c @subsubheading Example
17667 @subheading The @code{-data-disassemble} Command
17668 @findex -data-disassemble
17670 @subsubheading Synopsis
17674 [ -s @var{start-addr} -e @var{end-addr} ]
17675 | [ -f @var{filename} -l @var{linenum} [ -n @var{lines} ] ]
17683 @item @var{start-addr}
17684 is the beginning address (or @code{$pc})
17685 @item @var{end-addr}
17687 @item @var{filename}
17688 is the name of the file to disassemble
17689 @item @var{linenum}
17690 is the line number to disassemble around
17692 is the the number of disassembly lines to be produced. If it is -1,
17693 the whole function will be disassembled, in case no @var{end-addr} is
17694 specified. If @var{end-addr} is specified as a non-zero value, and
17695 @var{lines} is lower than the number of disassembly lines between
17696 @var{start-addr} and @var{end-addr}, only @var{lines} lines are
17697 displayed; if @var{lines} is higher than the number of lines between
17698 @var{start-addr} and @var{end-addr}, only the lines up to @var{end-addr}
17701 is either 0 (meaning only disassembly) or 1 (meaning mixed source and
17705 @subsubheading Result
17707 The output for each instruction is composed of four fields:
17716 Note that whatever included in the instruction field, is not manipulated
17717 directely by @sc{gdb/mi}, i.e. it is not possible to adjust its format.
17719 @subsubheading @value{GDBN} Command
17721 There's no direct mapping from this command to the CLI.
17723 @subsubheading Example
17725 Disassemble from the current value of @code{$pc} to @code{$pc + 20}:
17729 -data-disassemble -s $pc -e "$pc + 20" -- 0
17732 @{address="0x000107c0",func-name="main",offset="4",
17733 inst="mov 2, %o0"@},
17734 @{address="0x000107c4",func-name="main",offset="8",
17735 inst="sethi %hi(0x11800), %o2"@},
17736 @{address="0x000107c8",func-name="main",offset="12",
17737 inst="or %o2, 0x140, %o1\t! 0x11940 <_lib_version+8>"@},
17738 @{address="0x000107cc",func-name="main",offset="16",
17739 inst="sethi %hi(0x11800), %o2"@},
17740 @{address="0x000107d0",func-name="main",offset="20",
17741 inst="or %o2, 0x168, %o4\t! 0x11968 <_lib_version+48>"@}]
17745 Disassemble the whole @code{main} function. Line 32 is part of
17749 -data-disassemble -f basics.c -l 32 -- 0
17751 @{address="0x000107bc",func-name="main",offset="0",
17752 inst="save %sp, -112, %sp"@},
17753 @{address="0x000107c0",func-name="main",offset="4",
17754 inst="mov 2, %o0"@},
17755 @{address="0x000107c4",func-name="main",offset="8",
17756 inst="sethi %hi(0x11800), %o2"@},
17758 @{address="0x0001081c",func-name="main",offset="96",inst="ret "@},
17759 @{address="0x00010820",func-name="main",offset="100",inst="restore "@}]
17763 Disassemble 3 instructions from the start of @code{main}:
17767 -data-disassemble -f basics.c -l 32 -n 3 -- 0
17769 @{address="0x000107bc",func-name="main",offset="0",
17770 inst="save %sp, -112, %sp"@},
17771 @{address="0x000107c0",func-name="main",offset="4",
17772 inst="mov 2, %o0"@},
17773 @{address="0x000107c4",func-name="main",offset="8",
17774 inst="sethi %hi(0x11800), %o2"@}]
17778 Disassemble 3 instructions from the start of @code{main} in mixed mode:
17782 -data-disassemble -f basics.c -l 32 -n 3 -- 1
17784 src_and_asm_line=@{line="31",
17785 file="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb/ \
17786 testsuite/gdb.mi/basics.c",line_asm_insn=[
17787 @{address="0x000107bc",func-name="main",offset="0",
17788 inst="save %sp, -112, %sp"@}]@},
17789 src_and_asm_line=@{line="32",
17790 file="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb/ \
17791 testsuite/gdb.mi/basics.c",line_asm_insn=[
17792 @{address="0x000107c0",func-name="main",offset="4",
17793 inst="mov 2, %o0"@},
17794 @{address="0x000107c4",func-name="main",offset="8",
17795 inst="sethi %hi(0x11800), %o2"@}]@}]
17800 @subheading The @code{-data-evaluate-expression} Command
17801 @findex -data-evaluate-expression
17803 @subsubheading Synopsis
17806 -data-evaluate-expression @var{expr}
17809 Evaluate @var{expr} as an expression. The expression could contain an
17810 inferior function call. The function call will execute synchronously.
17811 If the expression contains spaces, it must be enclosed in double quotes.
17813 @subsubheading @value{GDBN} Command
17815 The corresponding @value{GDBN} commands are @samp{print}, @samp{output}, and
17816 @samp{call}. In @code{gdbtk} only, there's a corresponding
17817 @samp{gdb_eval} command.
17819 @subsubheading Example
17821 In the following example, the numbers that precede the commands are the
17822 @dfn{tokens} described in @ref{GDB/MI Command Syntax, ,@sc{gdb/mi}
17823 Command Syntax}. Notice how @sc{gdb/mi} returns the same tokens in its
17827 211-data-evaluate-expression A
17830 311-data-evaluate-expression &A
17831 311^done,value="0xefffeb7c"
17833 411-data-evaluate-expression A+3
17836 511-data-evaluate-expression "A + 3"
17842 @subheading The @code{-data-list-changed-registers} Command
17843 @findex -data-list-changed-registers
17845 @subsubheading Synopsis
17848 -data-list-changed-registers
17851 Display a list of the registers that have changed.
17853 @subsubheading @value{GDBN} Command
17855 @value{GDBN} doesn't have a direct analog for this command; @code{gdbtk}
17856 has the corresponding command @samp{gdb_changed_register_list}.
17858 @subsubheading Example
17860 On a PPC MBX board:
17868 *stopped,reason="breakpoint-hit",bkptno="1",frame=@{func="main",
17869 args=[],file="try.c",fullname="/home/foo/bar/devo/myproject/try.c",line="5"@}
17871 -data-list-changed-registers
17872 ^done,changed-registers=["0","1","2","4","5","6","7","8","9",
17873 "10","11","13","14","15","16","17","18","19","20","21","22","23",
17874 "24","25","26","27","28","30","31","64","65","66","67","69"]
17879 @subheading The @code{-data-list-register-names} Command
17880 @findex -data-list-register-names
17882 @subsubheading Synopsis
17885 -data-list-register-names [ ( @var{regno} )+ ]
17888 Show a list of register names for the current target. If no arguments
17889 are given, it shows a list of the names of all the registers. If
17890 integer numbers are given as arguments, it will print a list of the
17891 names of the registers corresponding to the arguments. To ensure
17892 consistency between a register name and its number, the output list may
17893 include empty register names.
17895 @subsubheading @value{GDBN} Command
17897 @value{GDBN} does not have a command which corresponds to
17898 @samp{-data-list-register-names}. In @code{gdbtk} there is a
17899 corresponding command @samp{gdb_regnames}.
17901 @subsubheading Example
17903 For the PPC MBX board:
17906 -data-list-register-names
17907 ^done,register-names=["r0","r1","r2","r3","r4","r5","r6","r7",
17908 "r8","r9","r10","r11","r12","r13","r14","r15","r16","r17","r18",
17909 "r19","r20","r21","r22","r23","r24","r25","r26","r27","r28","r29",
17910 "r30","r31","f0","f1","f2","f3","f4","f5","f6","f7","f8","f9",
17911 "f10","f11","f12","f13","f14","f15","f16","f17","f18","f19","f20",
17912 "f21","f22","f23","f24","f25","f26","f27","f28","f29","f30","f31",
17913 "", "pc","ps","cr","lr","ctr","xer"]
17915 -data-list-register-names 1 2 3
17916 ^done,register-names=["r1","r2","r3"]
17920 @subheading The @code{-data-list-register-values} Command
17921 @findex -data-list-register-values
17923 @subsubheading Synopsis
17926 -data-list-register-values @var{fmt} [ ( @var{regno} )*]
17929 Display the registers' contents. @var{fmt} is the format according to
17930 which the registers' contents are to be returned, followed by an optional
17931 list of numbers specifying the registers to display. A missing list of
17932 numbers indicates that the contents of all the registers must be returned.
17934 Allowed formats for @var{fmt} are:
17951 @subsubheading @value{GDBN} Command
17953 The corresponding @value{GDBN} commands are @samp{info reg}, @samp{info
17954 all-reg}, and (in @code{gdbtk}) @samp{gdb_fetch_registers}.
17956 @subsubheading Example
17958 For a PPC MBX board (note: line breaks are for readability only, they
17959 don't appear in the actual output):
17963 -data-list-register-values r 64 65
17964 ^done,register-values=[@{number="64",value="0xfe00a300"@},
17965 @{number="65",value="0x00029002"@}]
17967 -data-list-register-values x
17968 ^done,register-values=[@{number="0",value="0xfe0043c8"@},
17969 @{number="1",value="0x3fff88"@},@{number="2",value="0xfffffffe"@},
17970 @{number="3",value="0x0"@},@{number="4",value="0xa"@},
17971 @{number="5",value="0x3fff68"@},@{number="6",value="0x3fff58"@},
17972 @{number="7",value="0xfe011e98"@},@{number="8",value="0x2"@},
17973 @{number="9",value="0xfa202820"@},@{number="10",value="0xfa202808"@},
17974 @{number="11",value="0x1"@},@{number="12",value="0x0"@},
17975 @{number="13",value="0x4544"@},@{number="14",value="0xffdfffff"@},
17976 @{number="15",value="0xffffffff"@},@{number="16",value="0xfffffeff"@},
17977 @{number="17",value="0xefffffed"@},@{number="18",value="0xfffffffe"@},
17978 @{number="19",value="0xffffffff"@},@{number="20",value="0xffffffff"@},
17979 @{number="21",value="0xffffffff"@},@{number="22",value="0xfffffff7"@},
17980 @{number="23",value="0xffffffff"@},@{number="24",value="0xffffffff"@},
17981 @{number="25",value="0xffffffff"@},@{number="26",value="0xfffffffb"@},
17982 @{number="27",value="0xffffffff"@},@{number="28",value="0xf7bfffff"@},
17983 @{number="29",value="0x0"@},@{number="30",value="0xfe010000"@},
17984 @{number="31",value="0x0"@},@{number="32",value="0x0"@},
17985 @{number="33",value="0x0"@},@{number="34",value="0x0"@},
17986 @{number="35",value="0x0"@},@{number="36",value="0x0"@},
17987 @{number="37",value="0x0"@},@{number="38",value="0x0"@},
17988 @{number="39",value="0x0"@},@{number="40",value="0x0"@},
17989 @{number="41",value="0x0"@},@{number="42",value="0x0"@},
17990 @{number="43",value="0x0"@},@{number="44",value="0x0"@},
17991 @{number="45",value="0x0"@},@{number="46",value="0x0"@},
17992 @{number="47",value="0x0"@},@{number="48",value="0x0"@},
17993 @{number="49",value="0x0"@},@{number="50",value="0x0"@},
17994 @{number="51",value="0x0"@},@{number="52",value="0x0"@},
17995 @{number="53",value="0x0"@},@{number="54",value="0x0"@},
17996 @{number="55",value="0x0"@},@{number="56",value="0x0"@},
17997 @{number="57",value="0x0"@},@{number="58",value="0x0"@},
17998 @{number="59",value="0x0"@},@{number="60",value="0x0"@},
17999 @{number="61",value="0x0"@},@{number="62",value="0x0"@},
18000 @{number="63",value="0x0"@},@{number="64",value="0xfe00a300"@},
18001 @{number="65",value="0x29002"@},@{number="66",value="0x202f04b5"@},
18002 @{number="67",value="0xfe0043b0"@},@{number="68",value="0xfe00b3e4"@},
18003 @{number="69",value="0x20002b03"@}]
18008 @subheading The @code{-data-read-memory} Command
18009 @findex -data-read-memory
18011 @subsubheading Synopsis
18014 -data-read-memory [ -o @var{byte-offset} ]
18015 @var{address} @var{word-format} @var{word-size}
18016 @var{nr-rows} @var{nr-cols} [ @var{aschar} ]
18023 @item @var{address}
18024 An expression specifying the address of the first memory word to be
18025 read. Complex expressions containing embedded white space should be
18026 quoted using the C convention.
18028 @item @var{word-format}
18029 The format to be used to print the memory words. The notation is the
18030 same as for @value{GDBN}'s @code{print} command (@pxref{Output Formats,
18033 @item @var{word-size}
18034 The size of each memory word in bytes.
18036 @item @var{nr-rows}
18037 The number of rows in the output table.
18039 @item @var{nr-cols}
18040 The number of columns in the output table.
18043 If present, indicates that each row should include an @sc{ascii} dump. The
18044 value of @var{aschar} is used as a padding character when a byte is not a
18045 member of the printable @sc{ascii} character set (printable @sc{ascii}
18046 characters are those whose code is between 32 and 126, inclusively).
18048 @item @var{byte-offset}
18049 An offset to add to the @var{address} before fetching memory.
18052 This command displays memory contents as a table of @var{nr-rows} by
18053 @var{nr-cols} words, each word being @var{word-size} bytes. In total,
18054 @code{@var{nr-rows} * @var{nr-cols} * @var{word-size}} bytes are read
18055 (returned as @samp{total-bytes}). Should less than the requested number
18056 of bytes be returned by the target, the missing words are identified
18057 using @samp{N/A}. The number of bytes read from the target is returned
18058 in @samp{nr-bytes} and the starting address used to read memory in
18061 The address of the next/previous row or page is available in
18062 @samp{next-row} and @samp{prev-row}, @samp{next-page} and
18065 @subsubheading @value{GDBN} Command
18067 The corresponding @value{GDBN} command is @samp{x}. @code{gdbtk} has
18068 @samp{gdb_get_mem} memory read command.
18070 @subsubheading Example
18072 Read six bytes of memory starting at @code{bytes+6} but then offset by
18073 @code{-6} bytes. Format as three rows of two columns. One byte per
18074 word. Display each word in hex.
18078 9-data-read-memory -o -6 -- bytes+6 x 1 3 2
18079 9^done,addr="0x00001390",nr-bytes="6",total-bytes="6",
18080 next-row="0x00001396",prev-row="0x0000138e",next-page="0x00001396",
18081 prev-page="0x0000138a",memory=[
18082 @{addr="0x00001390",data=["0x00","0x01"]@},
18083 @{addr="0x00001392",data=["0x02","0x03"]@},
18084 @{addr="0x00001394",data=["0x04","0x05"]@}]
18088 Read two bytes of memory starting at address @code{shorts + 64} and
18089 display as a single word formatted in decimal.
18093 5-data-read-memory shorts+64 d 2 1 1
18094 5^done,addr="0x00001510",nr-bytes="2",total-bytes="2",
18095 next-row="0x00001512",prev-row="0x0000150e",
18096 next-page="0x00001512",prev-page="0x0000150e",memory=[
18097 @{addr="0x00001510",data=["128"]@}]
18101 Read thirty two bytes of memory starting at @code{bytes+16} and format
18102 as eight rows of four columns. Include a string encoding with @samp{x}
18103 used as the non-printable character.
18107 4-data-read-memory bytes+16 x 1 8 4 x
18108 4^done,addr="0x000013a0",nr-bytes="32",total-bytes="32",
18109 next-row="0x000013c0",prev-row="0x0000139c",
18110 next-page="0x000013c0",prev-page="0x00001380",memory=[
18111 @{addr="0x000013a0",data=["0x10","0x11","0x12","0x13"],ascii="xxxx"@},
18112 @{addr="0x000013a4",data=["0x14","0x15","0x16","0x17"],ascii="xxxx"@},
18113 @{addr="0x000013a8",data=["0x18","0x19","0x1a","0x1b"],ascii="xxxx"@},
18114 @{addr="0x000013ac",data=["0x1c","0x1d","0x1e","0x1f"],ascii="xxxx"@},
18115 @{addr="0x000013b0",data=["0x20","0x21","0x22","0x23"],ascii=" !\"#"@},
18116 @{addr="0x000013b4",data=["0x24","0x25","0x26","0x27"],ascii="$%&'"@},
18117 @{addr="0x000013b8",data=["0x28","0x29","0x2a","0x2b"],ascii="()*+"@},
18118 @{addr="0x000013bc",data=["0x2c","0x2d","0x2e","0x2f"],ascii=",-./"@}]
18122 @subheading The @code{-display-delete} Command
18123 @findex -display-delete
18125 @subsubheading Synopsis
18128 -display-delete @var{number}
18131 Delete the display @var{number}.
18133 @subsubheading @value{GDBN} Command
18135 The corresponding @value{GDBN} command is @samp{delete display}.
18137 @subsubheading Example
18141 @subheading The @code{-display-disable} Command
18142 @findex -display-disable
18144 @subsubheading Synopsis
18147 -display-disable @var{number}
18150 Disable display @var{number}.
18152 @subsubheading @value{GDBN} Command
18154 The corresponding @value{GDBN} command is @samp{disable display}.
18156 @subsubheading Example
18160 @subheading The @code{-display-enable} Command
18161 @findex -display-enable
18163 @subsubheading Synopsis
18166 -display-enable @var{number}
18169 Enable display @var{number}.
18171 @subsubheading @value{GDBN} Command
18173 The corresponding @value{GDBN} command is @samp{enable display}.
18175 @subsubheading Example
18179 @subheading The @code{-display-insert} Command
18180 @findex -display-insert
18182 @subsubheading Synopsis
18185 -display-insert @var{expression}
18188 Display @var{expression} every time the program stops.
18190 @subsubheading @value{GDBN} Command
18192 The corresponding @value{GDBN} command is @samp{display}.
18194 @subsubheading Example
18198 @subheading The @code{-display-list} Command
18199 @findex -display-list
18201 @subsubheading Synopsis
18207 List the displays. Do not show the current values.
18209 @subsubheading @value{GDBN} Command
18211 The corresponding @value{GDBN} command is @samp{info display}.
18213 @subsubheading Example
18217 @subheading The @code{-environment-cd} Command
18218 @findex -environment-cd
18220 @subsubheading Synopsis
18223 -environment-cd @var{pathdir}
18226 Set @value{GDBN}'s working directory.
18228 @subsubheading @value{GDBN} Command
18230 The corresponding @value{GDBN} command is @samp{cd}.
18232 @subsubheading Example
18236 -environment-cd /kwikemart/marge/ezannoni/flathead-dev/devo/gdb
18242 @subheading The @code{-environment-directory} Command
18243 @findex -environment-directory
18245 @subsubheading Synopsis
18248 -environment-directory [ -r ] [ @var{pathdir} ]+
18251 Add directories @var{pathdir} to beginning of search path for source files.
18252 If the @samp{-r} option is used, the search path is reset to the default
18253 search path. If directories @var{pathdir} are supplied in addition to the
18254 @samp{-r} option, the search path is first reset and then addition
18256 Multiple directories may be specified, separated by blanks. Specifying
18257 multiple directories in a single command
18258 results in the directories added to the beginning of the
18259 search path in the same order they were presented in the command.
18260 If blanks are needed as
18261 part of a directory name, double-quotes should be used around
18262 the name. In the command output, the path will show up separated
18263 by the system directory-separator character. The directory-seperator
18264 character must not be used
18265 in any directory name.
18266 If no directories are specified, the current search path is displayed.
18268 @subsubheading @value{GDBN} Command
18270 The corresponding @value{GDBN} command is @samp{dir}.
18272 @subsubheading Example
18276 -environment-directory /kwikemart/marge/ezannoni/flathead-dev/devo/gdb
18277 ^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd"
18279 -environment-directory ""
18280 ^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd"
18282 -environment-directory -r /home/jjohnstn/src/gdb /usr/src
18283 ^done,source-path="/home/jjohnstn/src/gdb:/usr/src:$cdir:$cwd"
18285 -environment-directory -r
18286 ^done,source-path="$cdir:$cwd"
18291 @subheading The @code{-environment-path} Command
18292 @findex -environment-path
18294 @subsubheading Synopsis
18297 -environment-path [ -r ] [ @var{pathdir} ]+
18300 Add directories @var{pathdir} to beginning of search path for object files.
18301 If the @samp{-r} option is used, the search path is reset to the original
18302 search path that existed at gdb start-up. If directories @var{pathdir} are
18303 supplied in addition to the
18304 @samp{-r} option, the search path is first reset and then addition
18306 Multiple directories may be specified, separated by blanks. Specifying
18307 multiple directories in a single command
18308 results in the directories added to the beginning of the
18309 search path in the same order they were presented in the command.
18310 If blanks are needed as
18311 part of a directory name, double-quotes should be used around
18312 the name. In the command output, the path will show up separated
18313 by the system directory-separator character. The directory-seperator
18314 character must not be used
18315 in any directory name.
18316 If no directories are specified, the current path is displayed.
18319 @subsubheading @value{GDBN} Command
18321 The corresponding @value{GDBN} command is @samp{path}.
18323 @subsubheading Example
18328 ^done,path="/usr/bin"
18330 -environment-path /kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb /bin
18331 ^done,path="/kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb:/bin:/usr/bin"
18333 -environment-path -r /usr/local/bin
18334 ^done,path="/usr/local/bin:/usr/bin"
18339 @subheading The @code{-environment-pwd} Command
18340 @findex -environment-pwd
18342 @subsubheading Synopsis
18348 Show the current working directory.
18350 @subsubheading @value{GDBN} command
18352 The corresponding @value{GDBN} command is @samp{pwd}.
18354 @subsubheading Example
18359 ^done,cwd="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb"
18363 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
18364 @node GDB/MI Program Control
18365 @section @sc{gdb/mi} Program control
18367 @subsubheading Program termination
18369 As a result of execution, the inferior program can run to completion, if
18370 it doesn't encounter any breakpoints. In this case the output will
18371 include an exit code, if the program has exited exceptionally.
18373 @subsubheading Examples
18376 Program exited normally:
18384 *stopped,reason="exited-normally"
18389 Program exited exceptionally:
18397 *stopped,reason="exited",exit-code="01"
18401 Another way the program can terminate is if it receives a signal such as
18402 @code{SIGINT}. In this case, @sc{gdb/mi} displays this:
18406 *stopped,reason="exited-signalled",signal-name="SIGINT",
18407 signal-meaning="Interrupt"
18411 @subheading The @code{-exec-abort} Command
18412 @findex -exec-abort
18414 @subsubheading Synopsis
18420 Kill the inferior running program.
18422 @subsubheading @value{GDBN} Command
18424 The corresponding @value{GDBN} command is @samp{kill}.
18426 @subsubheading Example
18430 @subheading The @code{-exec-arguments} Command
18431 @findex -exec-arguments
18433 @subsubheading Synopsis
18436 -exec-arguments @var{args}
18439 Set the inferior program arguments, to be used in the next
18442 @subsubheading @value{GDBN} Command
18444 The corresponding @value{GDBN} command is @samp{set args}.
18446 @subsubheading Example
18449 Don't have one around.
18452 @subheading The @code{-exec-continue} Command
18453 @findex -exec-continue
18455 @subsubheading Synopsis
18461 Asynchronous command. Resumes the execution of the inferior program
18462 until a breakpoint is encountered, or until the inferior exits.
18464 @subsubheading @value{GDBN} Command
18466 The corresponding @value{GDBN} corresponding is @samp{continue}.
18468 @subsubheading Example
18475 *stopped,reason="breakpoint-hit",bkptno="2",frame=@{func="foo",args=[],
18476 file="hello.c",fullname="/home/foo/bar/devo/myproject/hello.c",line="13"@}
18481 @subheading The @code{-exec-finish} Command
18482 @findex -exec-finish
18484 @subsubheading Synopsis
18490 Asynchronous command. Resumes the execution of the inferior program
18491 until the current function is exited. Displays the results returned by
18494 @subsubheading @value{GDBN} Command
18496 The corresponding @value{GDBN} command is @samp{finish}.
18498 @subsubheading Example
18500 Function returning @code{void}.
18507 *stopped,reason="function-finished",frame=@{func="main",args=[],
18508 file="hello.c",fullname="/home/foo/bar/devo/myproject/hello.c",line="7"@}
18512 Function returning other than @code{void}. The name of the internal
18513 @value{GDBN} variable storing the result is printed, together with the
18520 *stopped,reason="function-finished",frame=@{addr="0x000107b0",func="foo",
18521 args=[@{name="a",value="1"],@{name="b",value="9"@}@},
18522 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@},
18523 gdb-result-var="$1",return-value="0"
18528 @subheading The @code{-exec-interrupt} Command
18529 @findex -exec-interrupt
18531 @subsubheading Synopsis
18537 Asynchronous command. Interrupts the background execution of the target.
18538 Note how the token associated with the stop message is the one for the
18539 execution command that has been interrupted. The token for the interrupt
18540 itself only appears in the @samp{^done} output. If the user is trying to
18541 interrupt a non-running program, an error message will be printed.
18543 @subsubheading @value{GDBN} Command
18545 The corresponding @value{GDBN} command is @samp{interrupt}.
18547 @subsubheading Example
18558 111*stopped,signal-name="SIGINT",signal-meaning="Interrupt",
18559 frame=@{addr="0x00010140",func="foo",args=[],file="try.c",
18560 fullname="/home/foo/bar/devo/myproject/try.c",line="13"@}
18565 ^error,msg="mi_cmd_exec_interrupt: Inferior not executing."
18570 @subheading The @code{-exec-next} Command
18573 @subsubheading Synopsis
18579 Asynchronous command. Resumes execution of the inferior program, stopping
18580 when the beginning of the next source line is reached.
18582 @subsubheading @value{GDBN} Command
18584 The corresponding @value{GDBN} command is @samp{next}.
18586 @subsubheading Example
18592 *stopped,reason="end-stepping-range",line="8",file="hello.c"
18597 @subheading The @code{-exec-next-instruction} Command
18598 @findex -exec-next-instruction
18600 @subsubheading Synopsis
18603 -exec-next-instruction
18606 Asynchronous command. Executes one machine instruction. If the
18607 instruction is a function call continues until the function returns. If
18608 the program stops at an instruction in the middle of a source line, the
18609 address will be printed as well.
18611 @subsubheading @value{GDBN} Command
18613 The corresponding @value{GDBN} command is @samp{nexti}.
18615 @subsubheading Example
18619 -exec-next-instruction
18623 *stopped,reason="end-stepping-range",
18624 addr="0x000100d4",line="5",file="hello.c"
18629 @subheading The @code{-exec-return} Command
18630 @findex -exec-return
18632 @subsubheading Synopsis
18638 Makes current function return immediately. Doesn't execute the inferior.
18639 Displays the new current frame.
18641 @subsubheading @value{GDBN} Command
18643 The corresponding @value{GDBN} command is @samp{return}.
18645 @subsubheading Example
18649 200-break-insert callee4
18650 200^done,bkpt=@{number="1",addr="0x00010734",
18651 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8"@}
18656 000*stopped,reason="breakpoint-hit",bkptno="1",
18657 frame=@{func="callee4",args=[],
18658 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
18659 fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8"@}
18665 111^done,frame=@{level="0",func="callee3",
18666 args=[@{name="strarg",
18667 value="0x11940 \"A string argument.\""@}],
18668 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
18669 fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"@}
18674 @subheading The @code{-exec-run} Command
18677 @subsubheading Synopsis
18683 Asynchronous command. Starts execution of the inferior from the
18684 beginning. The inferior executes until either a breakpoint is
18685 encountered or the program exits.
18687 @subsubheading @value{GDBN} Command
18689 The corresponding @value{GDBN} command is @samp{run}.
18691 @subsubheading Example
18696 ^done,bkpt=@{number="1",addr="0x0001072c",file="recursive2.c",line="4"@}
18701 *stopped,reason="breakpoint-hit",bkptno="1",
18702 frame=@{func="main",args=[],file="recursive2.c",
18703 fullname="/home/foo/bar/devo/myproject/recursive2.c",line="4"@}
18708 @subheading The @code{-exec-show-arguments} Command
18709 @findex -exec-show-arguments
18711 @subsubheading Synopsis
18714 -exec-show-arguments
18717 Print the arguments of the program.
18719 @subsubheading @value{GDBN} Command
18721 The corresponding @value{GDBN} command is @samp{show args}.
18723 @subsubheading Example
18726 @c @subheading -exec-signal
18728 @subheading The @code{-exec-step} Command
18731 @subsubheading Synopsis
18737 Asynchronous command. Resumes execution of the inferior program, stopping
18738 when the beginning of the next source line is reached, if the next
18739 source line is not a function call. If it is, stop at the first
18740 instruction of the called function.
18742 @subsubheading @value{GDBN} Command
18744 The corresponding @value{GDBN} command is @samp{step}.
18746 @subsubheading Example
18748 Stepping into a function:
18754 *stopped,reason="end-stepping-range",
18755 frame=@{func="foo",args=[@{name="a",value="10"@},
18756 @{name="b",value="0"@}],file="recursive2.c",
18757 fullname="/home/foo/bar/devo/myproject/recursive2.c",line="11"@}
18767 *stopped,reason="end-stepping-range",line="14",file="recursive2.c"
18772 @subheading The @code{-exec-step-instruction} Command
18773 @findex -exec-step-instruction
18775 @subsubheading Synopsis
18778 -exec-step-instruction
18781 Asynchronous command. Resumes the inferior which executes one machine
18782 instruction. The output, once @value{GDBN} has stopped, will vary depending on
18783 whether we have stopped in the middle of a source line or not. In the
18784 former case, the address at which the program stopped will be printed as
18787 @subsubheading @value{GDBN} Command
18789 The corresponding @value{GDBN} command is @samp{stepi}.
18791 @subsubheading Example
18795 -exec-step-instruction
18799 *stopped,reason="end-stepping-range",
18800 frame=@{func="foo",args=[],file="try.c",
18801 fullname="/home/foo/bar/devo/myproject/try.c",line="10"@}
18803 -exec-step-instruction
18807 *stopped,reason="end-stepping-range",
18808 frame=@{addr="0x000100f4",func="foo",args=[],file="try.c",
18809 fullname="/home/foo/bar/devo/myproject/try.c",line="10"@}
18814 @subheading The @code{-exec-until} Command
18815 @findex -exec-until
18817 @subsubheading Synopsis
18820 -exec-until [ @var{location} ]
18823 Asynchronous command. Executes the inferior until the @var{location}
18824 specified in the argument is reached. If there is no argument, the inferior
18825 executes until a source line greater than the current one is reached.
18826 The reason for stopping in this case will be @samp{location-reached}.
18828 @subsubheading @value{GDBN} Command
18830 The corresponding @value{GDBN} command is @samp{until}.
18832 @subsubheading Example
18836 -exec-until recursive2.c:6
18840 *stopped,reason="location-reached",frame=@{func="main",args=[],
18841 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="6"@}
18846 @subheading -file-clear
18847 Is this going away????
18851 @subheading The @code{-file-exec-and-symbols} Command
18852 @findex -file-exec-and-symbols
18854 @subsubheading Synopsis
18857 -file-exec-and-symbols @var{file}
18860 Specify the executable file to be debugged. This file is the one from
18861 which the symbol table is also read. If no file is specified, the
18862 command clears the executable and symbol information. If breakpoints
18863 are set when using this command with no arguments, @value{GDBN} will produce
18864 error messages. Otherwise, no output is produced, except a completion
18867 @subsubheading @value{GDBN} Command
18869 The corresponding @value{GDBN} command is @samp{file}.
18871 @subsubheading Example
18875 -file-exec-and-symbols /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
18881 @subheading The @code{-file-exec-file} Command
18882 @findex -file-exec-file
18884 @subsubheading Synopsis
18887 -file-exec-file @var{file}
18890 Specify the executable file to be debugged. Unlike
18891 @samp{-file-exec-and-symbols}, the symbol table is @emph{not} read
18892 from this file. If used without argument, @value{GDBN} clears the information
18893 about the executable file. No output is produced, except a completion
18896 @subsubheading @value{GDBN} Command
18898 The corresponding @value{GDBN} command is @samp{exec-file}.
18900 @subsubheading Example
18904 -file-exec-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
18910 @subheading The @code{-file-list-exec-sections} Command
18911 @findex -file-list-exec-sections
18913 @subsubheading Synopsis
18916 -file-list-exec-sections
18919 List the sections of the current executable file.
18921 @subsubheading @value{GDBN} Command
18923 The @value{GDBN} command @samp{info file} shows, among the rest, the same
18924 information as this command. @code{gdbtk} has a corresponding command
18925 @samp{gdb_load_info}.
18927 @subsubheading Example
18931 @subheading The @code{-file-list-exec-source-file} Command
18932 @findex -file-list-exec-source-file
18934 @subsubheading Synopsis
18937 -file-list-exec-source-file
18940 List the line number, the current source file, and the absolute path
18941 to the current source file for the current executable.
18943 @subsubheading @value{GDBN} Command
18945 There's no @value{GDBN} command which directly corresponds to this one.
18947 @subsubheading Example
18951 123-file-list-exec-source-file
18952 123^done,line="1",file="foo.c",fullname="/home/bar/foo.c"
18957 @subheading The @code{-file-list-exec-source-files} Command
18958 @findex -file-list-exec-source-files
18960 @subsubheading Synopsis
18963 -file-list-exec-source-files
18966 List the source files for the current executable.
18968 It will always output the filename, but only when GDB can find the absolute
18969 file name of a source file, will it output the fullname.
18971 @subsubheading @value{GDBN} Command
18973 There's no @value{GDBN} command which directly corresponds to this one.
18974 @code{gdbtk} has an analogous command @samp{gdb_listfiles}.
18976 @subsubheading Example
18979 -file-list-exec-source-files
18981 @{file=foo.c,fullname=/home/foo.c@},
18982 @{file=/home/bar.c,fullname=/home/bar.c@},
18983 @{file=gdb_could_not_find_fullpath.c@}]
18987 @subheading The @code{-file-list-shared-libraries} Command
18988 @findex -file-list-shared-libraries
18990 @subsubheading Synopsis
18993 -file-list-shared-libraries
18996 List the shared libraries in the program.
18998 @subsubheading @value{GDBN} Command
19000 The corresponding @value{GDBN} command is @samp{info shared}.
19002 @subsubheading Example
19006 @subheading The @code{-file-list-symbol-files} Command
19007 @findex -file-list-symbol-files
19009 @subsubheading Synopsis
19012 -file-list-symbol-files
19017 @subsubheading @value{GDBN} Command
19019 The corresponding @value{GDBN} command is @samp{info file} (part of it).
19021 @subsubheading Example
19025 @subheading The @code{-file-symbol-file} Command
19026 @findex -file-symbol-file
19028 @subsubheading Synopsis
19031 -file-symbol-file @var{file}
19034 Read symbol table info from the specified @var{file} argument. When
19035 used without arguments, clears @value{GDBN}'s symbol table info. No output is
19036 produced, except for a completion notification.
19038 @subsubheading @value{GDBN} Command
19040 The corresponding @value{GDBN} command is @samp{symbol-file}.
19042 @subsubheading Example
19046 -file-symbol-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
19051 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
19052 @node GDB/MI Miscellaneous Commands
19053 @section Miscellaneous @value{GDBN} commands in @sc{gdb/mi}
19055 @c @subheading -gdb-complete
19057 @subheading The @code{-gdb-exit} Command
19060 @subsubheading Synopsis
19066 Exit @value{GDBN} immediately.
19068 @subsubheading @value{GDBN} Command
19070 Approximately corresponds to @samp{quit}.
19072 @subsubheading Example
19079 @subheading The @code{-gdb-set} Command
19082 @subsubheading Synopsis
19088 Set an internal @value{GDBN} variable.
19089 @c IS THIS A DOLLAR VARIABLE? OR SOMETHING LIKE ANNOTATE ?????
19091 @subsubheading @value{GDBN} Command
19093 The corresponding @value{GDBN} command is @samp{set}.
19095 @subsubheading Example
19105 @subheading The @code{-gdb-show} Command
19108 @subsubheading Synopsis
19114 Show the current value of a @value{GDBN} variable.
19116 @subsubheading @value{GDBN} command
19118 The corresponding @value{GDBN} command is @samp{show}.
19120 @subsubheading Example
19129 @c @subheading -gdb-source
19132 @subheading The @code{-gdb-version} Command
19133 @findex -gdb-version
19135 @subsubheading Synopsis
19141 Show version information for @value{GDBN}. Used mostly in testing.
19143 @subsubheading @value{GDBN} Command
19145 There's no equivalent @value{GDBN} command. @value{GDBN} by default shows this
19146 information when you start an interactive session.
19148 @subsubheading Example
19150 @c This example modifies the actual output from GDB to avoid overfull
19156 ~Copyright 2000 Free Software Foundation, Inc.
19157 ~GDB is free software, covered by the GNU General Public License, and
19158 ~you are welcome to change it and/or distribute copies of it under
19159 ~ certain conditions.
19160 ~Type "show copying" to see the conditions.
19161 ~There is absolutely no warranty for GDB. Type "show warranty" for
19163 ~This GDB was configured as
19164 "--host=sparc-sun-solaris2.5.1 --target=ppc-eabi".
19169 @subheading The @code{-interpreter-exec} Command
19170 @findex -interpreter-exec
19172 @subheading Synopsis
19175 -interpreter-exec @var{interpreter} @var{command}
19178 Execute the specified @var{command} in the given @var{interpreter}.
19180 @subheading @value{GDBN} Command
19182 The corresponding @value{GDBN} command is @samp{interpreter-exec}.
19184 @subheading Example
19188 -interpreter-exec console "break main"
19189 &"During symbol reading, couldn't parse type; debugger out of date?.\n"
19190 &"During symbol reading, bad structure-type format.\n"
19191 ~"Breakpoint 1 at 0x8074fc6: file ../../src/gdb/main.c, line 743.\n"
19196 @subheading The @code{-inferior-tty-set} Command
19197 @findex -inferior-tty-set
19199 @subheading Synopsis
19202 -inferior-tty-set /dev/pts/1
19205 Set terminal for future runs of the program being debugged.
19207 @subheading @value{GDBN} Command
19209 The corresponding @value{GDBN} command is @samp{set inferior-tty /dev/pts/1}.
19211 @subheading Example
19215 -inferior-tty-set /dev/pts/1
19220 @subheading The @code{-inferior-tty-show} Command
19221 @findex -inferior-tty-show
19223 @subheading Synopsis
19229 Show terminal for future runs of program being debugged.
19231 @subheading @value{GDBN} Command
19233 The corresponding @value{GDBN} command is @samp{show inferior-tty}.
19235 @subheading Example
19239 -inferior-tty-set /dev/pts/1
19243 ^done,inferior_tty_terminal="/dev/pts/1"
19248 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
19249 @node GDB/MI Kod Commands
19250 @section @sc{gdb/mi} Kod Commands
19252 The Kod commands are not implemented.
19254 @c @subheading -kod-info
19256 @c @subheading -kod-list
19258 @c @subheading -kod-list-object-types
19260 @c @subheading -kod-show
19262 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
19263 @node GDB/MI Memory Overlay Commands
19264 @section @sc{gdb/mi} Memory Overlay Commands
19266 The memory overlay commands are not implemented.
19268 @c @subheading -overlay-auto
19270 @c @subheading -overlay-list-mapping-state
19272 @c @subheading -overlay-list-overlays
19274 @c @subheading -overlay-map
19276 @c @subheading -overlay-off
19278 @c @subheading -overlay-on
19280 @c @subheading -overlay-unmap
19282 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
19283 @node GDB/MI Signal Handling Commands
19284 @section @sc{gdb/mi} Signal Handling Commands
19286 Signal handling commands are not implemented.
19288 @c @subheading -signal-handle
19290 @c @subheading -signal-list-handle-actions
19292 @c @subheading -signal-list-signal-types
19296 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
19297 @node GDB/MI Stack Manipulation
19298 @section @sc{gdb/mi} Stack Manipulation Commands
19301 @subheading The @code{-stack-info-frame} Command
19302 @findex -stack-info-frame
19304 @subsubheading Synopsis
19310 Get info on the selected frame.
19312 @subsubheading @value{GDBN} Command
19314 The corresponding @value{GDBN} command is @samp{info frame} or @samp{frame}
19315 (without arguments).
19317 @subsubheading Example
19322 ^done,frame=@{level="1",addr="0x0001076c",func="callee3",
19323 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
19324 fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="17"@}
19328 @subheading The @code{-stack-info-depth} Command
19329 @findex -stack-info-depth
19331 @subsubheading Synopsis
19334 -stack-info-depth [ @var{max-depth} ]
19337 Return the depth of the stack. If the integer argument @var{max-depth}
19338 is specified, do not count beyond @var{max-depth} frames.
19340 @subsubheading @value{GDBN} Command
19342 There's no equivalent @value{GDBN} command.
19344 @subsubheading Example
19346 For a stack with frame levels 0 through 11:
19353 -stack-info-depth 4
19356 -stack-info-depth 12
19359 -stack-info-depth 11
19362 -stack-info-depth 13
19367 @subheading The @code{-stack-list-arguments} Command
19368 @findex -stack-list-arguments
19370 @subsubheading Synopsis
19373 -stack-list-arguments @var{show-values}
19374 [ @var{low-frame} @var{high-frame} ]
19377 Display a list of the arguments for the frames between @var{low-frame}
19378 and @var{high-frame} (inclusive). If @var{low-frame} and
19379 @var{high-frame} are not provided, list the arguments for the whole call
19382 The @var{show-values} argument must have a value of 0 or 1. A value of
19383 0 means that only the names of the arguments are listed, a value of 1
19384 means that both names and values of the arguments are printed.
19386 @subsubheading @value{GDBN} Command
19388 @value{GDBN} does not have an equivalent command. @code{gdbtk} has a
19389 @samp{gdb_get_args} command which partially overlaps with the
19390 functionality of @samp{-stack-list-arguments}.
19392 @subsubheading Example
19399 frame=@{level="0",addr="0x00010734",func="callee4",
19400 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
19401 fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8"@},
19402 frame=@{level="1",addr="0x0001076c",func="callee3",
19403 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
19404 fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="17"@},
19405 frame=@{level="2",addr="0x0001078c",func="callee2",
19406 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
19407 fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="22"@},
19408 frame=@{level="3",addr="0x000107b4",func="callee1",
19409 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
19410 fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="27"@},
19411 frame=@{level="4",addr="0x000107e0",func="main",
19412 file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
19413 fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="32"@}]
19415 -stack-list-arguments 0
19418 frame=@{level="0",args=[]@},
19419 frame=@{level="1",args=[name="strarg"]@},
19420 frame=@{level="2",args=[name="intarg",name="strarg"]@},
19421 frame=@{level="3",args=[name="intarg",name="strarg",name="fltarg"]@},
19422 frame=@{level="4",args=[]@}]
19424 -stack-list-arguments 1
19427 frame=@{level="0",args=[]@},
19429 args=[@{name="strarg",value="0x11940 \"A string argument.\""@}]@},
19430 frame=@{level="2",args=[
19431 @{name="intarg",value="2"@},
19432 @{name="strarg",value="0x11940 \"A string argument.\""@}]@},
19433 @{frame=@{level="3",args=[
19434 @{name="intarg",value="2"@},
19435 @{name="strarg",value="0x11940 \"A string argument.\""@},
19436 @{name="fltarg",value="3.5"@}]@},
19437 frame=@{level="4",args=[]@}]
19439 -stack-list-arguments 0 2 2
19440 ^done,stack-args=[frame=@{level="2",args=[name="intarg",name="strarg"]@}]
19442 -stack-list-arguments 1 2 2
19443 ^done,stack-args=[frame=@{level="2",
19444 args=[@{name="intarg",value="2"@},
19445 @{name="strarg",value="0x11940 \"A string argument.\""@}]@}]
19449 @c @subheading -stack-list-exception-handlers
19452 @subheading The @code{-stack-list-frames} Command
19453 @findex -stack-list-frames
19455 @subsubheading Synopsis
19458 -stack-list-frames [ @var{low-frame} @var{high-frame} ]
19461 List the frames currently on the stack. For each frame it displays the
19466 The frame number, 0 being the topmost frame, i.e. the innermost function.
19468 The @code{$pc} value for that frame.
19472 File name of the source file where the function lives.
19474 Line number corresponding to the @code{$pc}.
19477 If invoked without arguments, this command prints a backtrace for the
19478 whole stack. If given two integer arguments, it shows the frames whose
19479 levels are between the two arguments (inclusive). If the two arguments
19480 are equal, it shows the single frame at the corresponding level.
19482 @subsubheading @value{GDBN} Command
19484 The corresponding @value{GDBN} commands are @samp{backtrace} and @samp{where}.
19486 @subsubheading Example
19488 Full stack backtrace:
19494 [frame=@{level="0",addr="0x0001076c",func="foo",
19495 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="11"@},
19496 frame=@{level="1",addr="0x000107a4",func="foo",
19497 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@},
19498 frame=@{level="2",addr="0x000107a4",func="foo",
19499 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@},
19500 frame=@{level="3",addr="0x000107a4",func="foo",
19501 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@},
19502 frame=@{level="4",addr="0x000107a4",func="foo",
19503 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@},
19504 frame=@{level="5",addr="0x000107a4",func="foo",
19505 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@},
19506 frame=@{level="6",addr="0x000107a4",func="foo",
19507 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@},
19508 frame=@{level="7",addr="0x000107a4",func="foo",
19509 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@},
19510 frame=@{level="8",addr="0x000107a4",func="foo",
19511 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@},
19512 frame=@{level="9",addr="0x000107a4",func="foo",
19513 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@},
19514 frame=@{level="10",addr="0x000107a4",func="foo",
19515 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@},
19516 frame=@{level="11",addr="0x00010738",func="main",
19517 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="4"@}]
19521 Show frames between @var{low_frame} and @var{high_frame}:
19525 -stack-list-frames 3 5
19527 [frame=@{level="3",addr="0x000107a4",func="foo",
19528 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@},
19529 frame=@{level="4",addr="0x000107a4",func="foo",
19530 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@},
19531 frame=@{level="5",addr="0x000107a4",func="foo",
19532 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@}]
19536 Show a single frame:
19540 -stack-list-frames 3 3
19542 [frame=@{level="3",addr="0x000107a4",func="foo",
19543 file="recursive2.c",fullname="/home/foo/bar/devo/myproject/recursive2.c",line="14"@}]
19548 @subheading The @code{-stack-list-locals} Command
19549 @findex -stack-list-locals
19551 @subsubheading Synopsis
19554 -stack-list-locals @var{print-values}
19557 Display the local variable names for the selected frame. If
19558 @var{print-values} is 0 or @code{--no-values}, print only the names of
19559 the variables; if it is 1 or @code{--all-values}, print also their
19560 values; and if it is 2 or @code{--simple-values}, print the name,
19561 type and value for simple data types and the name and type for arrays,
19562 structures and unions. In this last case, a frontend can immediately
19563 display the value of simple data types and create variable objects for
19564 other data types when the the user wishes to explore their values in
19567 @subsubheading @value{GDBN} Command
19569 @samp{info locals} in @value{GDBN}, @samp{gdb_get_locals} in @code{gdbtk}.
19571 @subsubheading Example
19575 -stack-list-locals 0
19576 ^done,locals=[name="A",name="B",name="C"]
19578 -stack-list-locals --all-values
19579 ^done,locals=[@{name="A",value="1"@},@{name="B",value="2"@},
19580 @{name="C",value="@{1, 2, 3@}"@}]
19581 -stack-list-locals --simple-values
19582 ^done,locals=[@{name="A",type="int",value="1"@},
19583 @{name="B",type="int",value="2"@},@{name="C",type="int [3]"@}]
19588 @subheading The @code{-stack-select-frame} Command
19589 @findex -stack-select-frame
19591 @subsubheading Synopsis
19594 -stack-select-frame @var{framenum}
19597 Change the selected frame. Select a different frame @var{framenum} on
19600 @subsubheading @value{GDBN} Command
19602 The corresponding @value{GDBN} commands are @samp{frame}, @samp{up},
19603 @samp{down}, @samp{select-frame}, @samp{up-silent}, and @samp{down-silent}.
19605 @subsubheading Example
19609 -stack-select-frame 2
19614 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
19615 @node GDB/MI Symbol Query
19616 @section @sc{gdb/mi} Symbol Query Commands
19619 @subheading The @code{-symbol-info-address} Command
19620 @findex -symbol-info-address
19622 @subsubheading Synopsis
19625 -symbol-info-address @var{symbol}
19628 Describe where @var{symbol} is stored.
19630 @subsubheading @value{GDBN} Command
19632 The corresponding @value{GDBN} command is @samp{info address}.
19634 @subsubheading Example
19638 @subheading The @code{-symbol-info-file} Command
19639 @findex -symbol-info-file
19641 @subsubheading Synopsis
19647 Show the file for the symbol.
19649 @subsubheading @value{GDBN} Command
19651 There's no equivalent @value{GDBN} command. @code{gdbtk} has
19652 @samp{gdb_find_file}.
19654 @subsubheading Example
19658 @subheading The @code{-symbol-info-function} Command
19659 @findex -symbol-info-function
19661 @subsubheading Synopsis
19664 -symbol-info-function
19667 Show which function the symbol lives in.
19669 @subsubheading @value{GDBN} Command
19671 @samp{gdb_get_function} in @code{gdbtk}.
19673 @subsubheading Example
19677 @subheading The @code{-symbol-info-line} Command
19678 @findex -symbol-info-line
19680 @subsubheading Synopsis
19686 Show the core addresses of the code for a source line.
19688 @subsubheading @value{GDBN} Command
19690 The corresponding @value{GDBN} command is @samp{info line}.
19691 @code{gdbtk} has the @samp{gdb_get_line} and @samp{gdb_get_file} commands.
19693 @subsubheading Example
19697 @subheading The @code{-symbol-info-symbol} Command
19698 @findex -symbol-info-symbol
19700 @subsubheading Synopsis
19703 -symbol-info-symbol @var{addr}
19706 Describe what symbol is at location @var{addr}.
19708 @subsubheading @value{GDBN} Command
19710 The corresponding @value{GDBN} command is @samp{info symbol}.
19712 @subsubheading Example
19716 @subheading The @code{-symbol-list-functions} Command
19717 @findex -symbol-list-functions
19719 @subsubheading Synopsis
19722 -symbol-list-functions
19725 List the functions in the executable.
19727 @subsubheading @value{GDBN} Command
19729 @samp{info functions} in @value{GDBN}, @samp{gdb_listfunc} and
19730 @samp{gdb_search} in @code{gdbtk}.
19732 @subsubheading Example
19736 @subheading The @code{-symbol-list-lines} Command
19737 @findex -symbol-list-lines
19739 @subsubheading Synopsis
19742 -symbol-list-lines @var{filename}
19745 Print the list of lines that contain code and their associated program
19746 addresses for the given source filename. The entries are sorted in
19747 ascending PC order.
19749 @subsubheading @value{GDBN} Command
19751 There is no corresponding @value{GDBN} command.
19753 @subsubheading Example
19756 -symbol-list-lines basics.c
19757 ^done,lines=[@{pc="0x08048554",line="7"@},@{pc="0x0804855a",line="8"@}]
19762 @subheading The @code{-symbol-list-types} Command
19763 @findex -symbol-list-types
19765 @subsubheading Synopsis
19771 List all the type names.
19773 @subsubheading @value{GDBN} Command
19775 The corresponding commands are @samp{info types} in @value{GDBN},
19776 @samp{gdb_search} in @code{gdbtk}.
19778 @subsubheading Example
19782 @subheading The @code{-symbol-list-variables} Command
19783 @findex -symbol-list-variables
19785 @subsubheading Synopsis
19788 -symbol-list-variables
19791 List all the global and static variable names.
19793 @subsubheading @value{GDBN} Command
19795 @samp{info variables} in @value{GDBN}, @samp{gdb_search} in @code{gdbtk}.
19797 @subsubheading Example
19801 @subheading The @code{-symbol-locate} Command
19802 @findex -symbol-locate
19804 @subsubheading Synopsis
19810 @subsubheading @value{GDBN} Command
19812 @samp{gdb_loc} in @code{gdbtk}.
19814 @subsubheading Example
19818 @subheading The @code{-symbol-type} Command
19819 @findex -symbol-type
19821 @subsubheading Synopsis
19824 -symbol-type @var{variable}
19827 Show type of @var{variable}.
19829 @subsubheading @value{GDBN} Command
19831 The corresponding @value{GDBN} command is @samp{ptype}, @code{gdbtk} has
19832 @samp{gdb_obj_variable}.
19834 @subsubheading Example
19838 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
19839 @node GDB/MI Target Manipulation
19840 @section @sc{gdb/mi} Target Manipulation Commands
19843 @subheading The @code{-target-attach} Command
19844 @findex -target-attach
19846 @subsubheading Synopsis
19849 -target-attach @var{pid} | @var{file}
19852 Attach to a process @var{pid} or a file @var{file} outside of @value{GDBN}.
19854 @subsubheading @value{GDBN} command
19856 The corresponding @value{GDBN} command is @samp{attach}.
19858 @subsubheading Example
19862 @subheading The @code{-target-compare-sections} Command
19863 @findex -target-compare-sections
19865 @subsubheading Synopsis
19868 -target-compare-sections [ @var{section} ]
19871 Compare data of section @var{section} on target to the exec file.
19872 Without the argument, all sections are compared.
19874 @subsubheading @value{GDBN} Command
19876 The @value{GDBN} equivalent is @samp{compare-sections}.
19878 @subsubheading Example
19882 @subheading The @code{-target-detach} Command
19883 @findex -target-detach
19885 @subsubheading Synopsis
19891 Disconnect from the remote target. There's no output.
19893 @subsubheading @value{GDBN} command
19895 The corresponding @value{GDBN} command is @samp{detach}.
19897 @subsubheading Example
19907 @subheading The @code{-target-disconnect} Command
19908 @findex -target-disconnect
19910 @subsubheading Synopsis
19916 Disconnect from the remote target. There's no output.
19918 @subsubheading @value{GDBN} command
19920 The corresponding @value{GDBN} command is @samp{disconnect}.
19922 @subsubheading Example
19932 @subheading The @code{-target-download} Command
19933 @findex -target-download
19935 @subsubheading Synopsis
19941 Loads the executable onto the remote target.
19942 It prints out an update message every half second, which includes the fields:
19946 The name of the section.
19948 The size of what has been sent so far for that section.
19950 The size of the section.
19952 The total size of what was sent so far (the current and the previous sections).
19954 The size of the overall executable to download.
19958 Each message is sent as status record (@pxref{GDB/MI Output Syntax, ,
19959 @sc{gdb/mi} Output Syntax}).
19961 In addition, it prints the name and size of the sections, as they are
19962 downloaded. These messages include the following fields:
19966 The name of the section.
19968 The size of the section.
19970 The size of the overall executable to download.
19974 At the end, a summary is printed.
19976 @subsubheading @value{GDBN} Command
19978 The corresponding @value{GDBN} command is @samp{load}.
19980 @subsubheading Example
19982 Note: each status message appears on a single line. Here the messages
19983 have been broken down so that they can fit onto a page.
19988 +download,@{section=".text",section-size="6668",total-size="9880"@}
19989 +download,@{section=".text",section-sent="512",section-size="6668",
19990 total-sent="512",total-size="9880"@}
19991 +download,@{section=".text",section-sent="1024",section-size="6668",
19992 total-sent="1024",total-size="9880"@}
19993 +download,@{section=".text",section-sent="1536",section-size="6668",
19994 total-sent="1536",total-size="9880"@}
19995 +download,@{section=".text",section-sent="2048",section-size="6668",
19996 total-sent="2048",total-size="9880"@}
19997 +download,@{section=".text",section-sent="2560",section-size="6668",
19998 total-sent="2560",total-size="9880"@}
19999 +download,@{section=".text",section-sent="3072",section-size="6668",
20000 total-sent="3072",total-size="9880"@}
20001 +download,@{section=".text",section-sent="3584",section-size="6668",
20002 total-sent="3584",total-size="9880"@}
20003 +download,@{section=".text",section-sent="4096",section-size="6668",
20004 total-sent="4096",total-size="9880"@}
20005 +download,@{section=".text",section-sent="4608",section-size="6668",
20006 total-sent="4608",total-size="9880"@}
20007 +download,@{section=".text",section-sent="5120",section-size="6668",
20008 total-sent="5120",total-size="9880"@}
20009 +download,@{section=".text",section-sent="5632",section-size="6668",
20010 total-sent="5632",total-size="9880"@}
20011 +download,@{section=".text",section-sent="6144",section-size="6668",
20012 total-sent="6144",total-size="9880"@}
20013 +download,@{section=".text",section-sent="6656",section-size="6668",
20014 total-sent="6656",total-size="9880"@}
20015 +download,@{section=".init",section-size="28",total-size="9880"@}
20016 +download,@{section=".fini",section-size="28",total-size="9880"@}
20017 +download,@{section=".data",section-size="3156",total-size="9880"@}
20018 +download,@{section=".data",section-sent="512",section-size="3156",
20019 total-sent="7236",total-size="9880"@}
20020 +download,@{section=".data",section-sent="1024",section-size="3156",
20021 total-sent="7748",total-size="9880"@}
20022 +download,@{section=".data",section-sent="1536",section-size="3156",
20023 total-sent="8260",total-size="9880"@}
20024 +download,@{section=".data",section-sent="2048",section-size="3156",
20025 total-sent="8772",total-size="9880"@}
20026 +download,@{section=".data",section-sent="2560",section-size="3156",
20027 total-sent="9284",total-size="9880"@}
20028 +download,@{section=".data",section-sent="3072",section-size="3156",
20029 total-sent="9796",total-size="9880"@}
20030 ^done,address="0x10004",load-size="9880",transfer-rate="6586",
20036 @subheading The @code{-target-exec-status} Command
20037 @findex -target-exec-status
20039 @subsubheading Synopsis
20042 -target-exec-status
20045 Provide information on the state of the target (whether it is running or
20046 not, for instance).
20048 @subsubheading @value{GDBN} Command
20050 There's no equivalent @value{GDBN} command.
20052 @subsubheading Example
20056 @subheading The @code{-target-list-available-targets} Command
20057 @findex -target-list-available-targets
20059 @subsubheading Synopsis
20062 -target-list-available-targets
20065 List the possible targets to connect to.
20067 @subsubheading @value{GDBN} Command
20069 The corresponding @value{GDBN} command is @samp{help target}.
20071 @subsubheading Example
20075 @subheading The @code{-target-list-current-targets} Command
20076 @findex -target-list-current-targets
20078 @subsubheading Synopsis
20081 -target-list-current-targets
20084 Describe the current target.
20086 @subsubheading @value{GDBN} Command
20088 The corresponding information is printed by @samp{info file} (among
20091 @subsubheading Example
20095 @subheading The @code{-target-list-parameters} Command
20096 @findex -target-list-parameters
20098 @subsubheading Synopsis
20101 -target-list-parameters
20106 @subsubheading @value{GDBN} Command
20110 @subsubheading Example
20114 @subheading The @code{-target-select} Command
20115 @findex -target-select
20117 @subsubheading Synopsis
20120 -target-select @var{type} @var{parameters @dots{}}
20123 Connect @value{GDBN} to the remote target. This command takes two args:
20127 The type of target, for instance @samp{async}, @samp{remote}, etc.
20128 @item @var{parameters}
20129 Device names, host names and the like. @xref{Target Commands, ,
20130 Commands for managing targets}, for more details.
20133 The output is a connection notification, followed by the address at
20134 which the target program is, in the following form:
20137 ^connected,addr="@var{address}",func="@var{function name}",
20138 args=[@var{arg list}]
20141 @subsubheading @value{GDBN} Command
20143 The corresponding @value{GDBN} command is @samp{target}.
20145 @subsubheading Example
20149 -target-select async /dev/ttya
20150 ^connected,addr="0xfe00a300",func="??",args=[]
20154 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
20155 @node GDB/MI Thread Commands
20156 @section @sc{gdb/mi} Thread Commands
20159 @subheading The @code{-thread-info} Command
20160 @findex -thread-info
20162 @subsubheading Synopsis
20168 @subsubheading @value{GDBN} command
20172 @subsubheading Example
20176 @subheading The @code{-thread-list-all-threads} Command
20177 @findex -thread-list-all-threads
20179 @subsubheading Synopsis
20182 -thread-list-all-threads
20185 @subsubheading @value{GDBN} Command
20187 The equivalent @value{GDBN} command is @samp{info threads}.
20189 @subsubheading Example
20193 @subheading The @code{-thread-list-ids} Command
20194 @findex -thread-list-ids
20196 @subsubheading Synopsis
20202 Produces a list of the currently known @value{GDBN} thread ids. At the
20203 end of the list it also prints the total number of such threads.
20205 @subsubheading @value{GDBN} Command
20207 Part of @samp{info threads} supplies the same information.
20209 @subsubheading Example
20211 No threads present, besides the main process:
20216 ^done,thread-ids=@{@},number-of-threads="0"
20226 ^done,thread-ids=@{thread-id="3",thread-id="2",thread-id="1"@},
20227 number-of-threads="3"
20232 @subheading The @code{-thread-select} Command
20233 @findex -thread-select
20235 @subsubheading Synopsis
20238 -thread-select @var{threadnum}
20241 Make @var{threadnum} the current thread. It prints the number of the new
20242 current thread, and the topmost frame for that thread.
20244 @subsubheading @value{GDBN} Command
20246 The corresponding @value{GDBN} command is @samp{thread}.
20248 @subsubheading Example
20255 *stopped,reason="end-stepping-range",thread-id="2",line="187",
20256 file="../../../devo/gdb/testsuite/gdb.threads/linux-dp.c"
20260 thread-ids=@{thread-id="3",thread-id="2",thread-id="1"@},
20261 number-of-threads="3"
20264 ^done,new-thread-id="3",
20265 frame=@{level="0",func="vprintf",
20266 args=[@{name="format",value="0x8048e9c \"%*s%c %d %c\\n\""@},
20267 @{name="arg",value="0x2"@}],file="vprintf.c",line="31"@}
20271 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
20272 @node GDB/MI Tracepoint Commands
20273 @section @sc{gdb/mi} Tracepoint Commands
20275 The tracepoint commands are not yet implemented.
20277 @c @subheading -trace-actions
20279 @c @subheading -trace-delete
20281 @c @subheading -trace-disable
20283 @c @subheading -trace-dump
20285 @c @subheading -trace-enable
20287 @c @subheading -trace-exists
20289 @c @subheading -trace-find
20291 @c @subheading -trace-frame-number
20293 @c @subheading -trace-info
20295 @c @subheading -trace-insert
20297 @c @subheading -trace-list
20299 @c @subheading -trace-pass-count
20301 @c @subheading -trace-save
20303 @c @subheading -trace-start
20305 @c @subheading -trace-stop
20308 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
20309 @node GDB/MI Variable Objects
20310 @section @sc{gdb/mi} Variable Objects
20313 @subheading Motivation for Variable Objects in @sc{gdb/mi}
20315 For the implementation of a variable debugger window (locals, watched
20316 expressions, etc.), we are proposing the adaptation of the existing code
20317 used by @code{Insight}.
20319 The two main reasons for that are:
20323 It has been proven in practice (it is already on its second generation).
20326 It will shorten development time (needless to say how important it is
20330 The original interface was designed to be used by Tcl code, so it was
20331 slightly changed so it could be used through @sc{gdb/mi}. This section
20332 describes the @sc{gdb/mi} operations that will be available and gives some
20333 hints about their use.
20335 @emph{Note}: In addition to the set of operations described here, we
20336 expect the @sc{gui} implementation of a variable window to require, at
20337 least, the following operations:
20340 @item @code{-gdb-show} @code{output-radix}
20341 @item @code{-stack-list-arguments}
20342 @item @code{-stack-list-locals}
20343 @item @code{-stack-select-frame}
20346 @subheading Introduction to Variable Objects in @sc{gdb/mi}
20348 @cindex variable objects in @sc{gdb/mi}
20349 The basic idea behind variable objects is the creation of a named object
20350 to represent a variable, an expression, a memory location or even a CPU
20351 register. For each object created, a set of operations is available for
20352 examining or changing its properties.
20354 Furthermore, complex data types, such as C structures, are represented
20355 in a tree format. For instance, the @code{struct} type variable is the
20356 root and the children will represent the struct members. If a child
20357 is itself of a complex type, it will also have children of its own.
20358 Appropriate language differences are handled for C, C@t{++} and Java.
20360 When returning the actual values of the objects, this facility allows
20361 for the individual selection of the display format used in the result
20362 creation. It can be chosen among: binary, decimal, hexadecimal, octal
20363 and natural. Natural refers to a default format automatically
20364 chosen based on the variable type (like decimal for an @code{int}, hex
20365 for pointers, etc.).
20367 The following is the complete set of @sc{gdb/mi} operations defined to
20368 access this functionality:
20370 @multitable @columnfractions .4 .6
20371 @item @strong{Operation}
20372 @tab @strong{Description}
20374 @item @code{-var-create}
20375 @tab create a variable object
20376 @item @code{-var-delete}
20377 @tab delete the variable object and its children
20378 @item @code{-var-set-format}
20379 @tab set the display format of this variable
20380 @item @code{-var-show-format}
20381 @tab show the display format of this variable
20382 @item @code{-var-info-num-children}
20383 @tab tells how many children this object has
20384 @item @code{-var-list-children}
20385 @tab return a list of the object's children
20386 @item @code{-var-info-type}
20387 @tab show the type of this variable object
20388 @item @code{-var-info-expression}
20389 @tab print what this variable object represents
20390 @item @code{-var-show-attributes}
20391 @tab is this variable editable? does it exist here?
20392 @item @code{-var-evaluate-expression}
20393 @tab get the value of this variable
20394 @item @code{-var-assign}
20395 @tab set the value of this variable
20396 @item @code{-var-update}
20397 @tab update the variable and its children
20400 In the next subsection we describe each operation in detail and suggest
20401 how it can be used.
20403 @subheading Description And Use of Operations on Variable Objects
20405 @subheading The @code{-var-create} Command
20406 @findex -var-create
20408 @subsubheading Synopsis
20411 -var-create @{@var{name} | "-"@}
20412 @{@var{frame-addr} | "*"@} @var{expression}
20415 This operation creates a variable object, which allows the monitoring of
20416 a variable, the result of an expression, a memory cell or a CPU
20419 The @var{name} parameter is the string by which the object can be
20420 referenced. It must be unique. If @samp{-} is specified, the varobj
20421 system will generate a string ``varNNNNNN'' automatically. It will be
20422 unique provided that one does not specify @var{name} on that format.
20423 The command fails if a duplicate name is found.
20425 The frame under which the expression should be evaluated can be
20426 specified by @var{frame-addr}. A @samp{*} indicates that the current
20427 frame should be used.
20429 @var{expression} is any expression valid on the current language set (must not
20430 begin with a @samp{*}), or one of the following:
20434 @samp{*@var{addr}}, where @var{addr} is the address of a memory cell
20437 @samp{*@var{addr}-@var{addr}} --- a memory address range (TBD)
20440 @samp{$@var{regname}} --- a CPU register name
20443 @subsubheading Result
20445 This operation returns the name, number of children and the type of the
20446 object created. Type is returned as a string as the ones generated by
20447 the @value{GDBN} CLI:
20450 name="@var{name}",numchild="N",type="@var{type}"
20454 @subheading The @code{-var-delete} Command
20455 @findex -var-delete
20457 @subsubheading Synopsis
20460 -var-delete @var{name}
20463 Deletes a previously created variable object and all of its children.
20465 Returns an error if the object @var{name} is not found.
20468 @subheading The @code{-var-set-format} Command
20469 @findex -var-set-format
20471 @subsubheading Synopsis
20474 -var-set-format @var{name} @var{format-spec}
20477 Sets the output format for the value of the object @var{name} to be
20480 The syntax for the @var{format-spec} is as follows:
20483 @var{format-spec} @expansion{}
20484 @{binary | decimal | hexadecimal | octal | natural@}
20488 @subheading The @code{-var-show-format} Command
20489 @findex -var-show-format
20491 @subsubheading Synopsis
20494 -var-show-format @var{name}
20497 Returns the format used to display the value of the object @var{name}.
20500 @var{format} @expansion{}
20505 @subheading The @code{-var-info-num-children} Command
20506 @findex -var-info-num-children
20508 @subsubheading Synopsis
20511 -var-info-num-children @var{name}
20514 Returns the number of children of a variable object @var{name}:
20521 @subheading The @code{-var-list-children} Command
20522 @findex -var-list-children
20524 @subsubheading Synopsis
20527 -var-list-children [@var{print-values}] @var{name}
20529 @anchor{-var-list-children}
20531 Return a list of the children of the specified variable object and
20532 create variable objects for them, if they do not already exist. With
20533 a single argument or if @var{print-values} has a value for of 0 or
20534 @code{--no-values}, print only the names of the variables; if
20535 @var{print-values} is 1 or @code{--all-values}, also print their
20536 values; and if it is 2 or @code{--simple-values} print the name and
20537 value for simple data types and just the name for arrays, structures
20540 @subsubheading Example
20544 -var-list-children n
20545 ^done,numchild=@var{n},children=[@{name=@var{name},
20546 numchild=@var{n},type=@var{type}@},@r{(repeats N times)}]
20548 -var-list-children --all-values n
20549 ^done,numchild=@var{n},children=[@{name=@var{name},
20550 numchild=@var{n},value=@var{value},type=@var{type}@},@r{(repeats N times)}]
20554 @subheading The @code{-var-info-type} Command
20555 @findex -var-info-type
20557 @subsubheading Synopsis
20560 -var-info-type @var{name}
20563 Returns the type of the specified variable @var{name}. The type is
20564 returned as a string in the same format as it is output by the
20568 type=@var{typename}
20572 @subheading The @code{-var-info-expression} Command
20573 @findex -var-info-expression
20575 @subsubheading Synopsis
20578 -var-info-expression @var{name}
20581 Returns what is represented by the variable object @var{name}:
20584 lang=@var{lang-spec},exp=@var{expression}
20588 where @var{lang-spec} is @code{@{"C" | "C++" | "Java"@}}.
20590 @subheading The @code{-var-show-attributes} Command
20591 @findex -var-show-attributes
20593 @subsubheading Synopsis
20596 -var-show-attributes @var{name}
20599 List attributes of the specified variable object @var{name}:
20602 status=@var{attr} [ ( ,@var{attr} )* ]
20606 where @var{attr} is @code{@{ @{ editable | noneditable @} | TBD @}}.
20608 @subheading The @code{-var-evaluate-expression} Command
20609 @findex -var-evaluate-expression
20611 @subsubheading Synopsis
20614 -var-evaluate-expression @var{name}
20617 Evaluates the expression that is represented by the specified variable
20618 object and returns its value as a string in the current format specified
20625 Note that one must invoke @code{-var-list-children} for a variable
20626 before the value of a child variable can be evaluated.
20628 @subheading The @code{-var-assign} Command
20629 @findex -var-assign
20631 @subsubheading Synopsis
20634 -var-assign @var{name} @var{expression}
20637 Assigns the value of @var{expression} to the variable object specified
20638 by @var{name}. The object must be @samp{editable}. If the variable's
20639 value is altered by the assign, the variable will show up in any
20640 subsequent @code{-var-update} list.
20642 @subsubheading Example
20650 ^done,changelist=[@{name="var1",in_scope="true",type_changed="false"@}]
20654 @subheading The @code{-var-update} Command
20655 @findex -var-update
20657 @subsubheading Synopsis
20660 -var-update [@var{print-values}] @{@var{name} | "*"@}
20663 Update the value of the variable object @var{name} by evaluating its
20664 expression after fetching all the new values from memory or registers.
20665 A @samp{*} causes all existing variable objects to be updated. The
20666 option @var{print-values} determines whether names and values, or just
20667 names are printed in the manner described for
20668 @code{@pxref{-var-list-children}}.
20670 @subsubheading Example
20677 -var-update --all-values var1
20678 ^done,changelist=[@{name="var1",value="3",in_scope="true",
20679 type_changed="false"@}]
20684 @chapter @value{GDBN} Annotations
20686 This chapter describes annotations in @value{GDBN}. Annotations were
20687 designed to interface @value{GDBN} to graphical user interfaces or other
20688 similar programs which want to interact with @value{GDBN} at a
20689 relatively high level.
20691 The annotation mechanism has largely been superseeded by @sc{gdb/mi}
20695 This is Edition @value{EDITION}, @value{DATE}.
20699 * Annotations Overview:: What annotations are; the general syntax.
20700 * Prompting:: Annotations marking @value{GDBN}'s need for input.
20701 * Errors:: Annotations for error messages.
20702 * Invalidation:: Some annotations describe things now invalid.
20703 * Annotations for Running::
20704 Whether the program is running, how it stopped, etc.
20705 * Source Annotations:: Annotations describing source code.
20708 @node Annotations Overview
20709 @section What is an Annotation?
20710 @cindex annotations
20712 Annotations start with a newline character, two @samp{control-z}
20713 characters, and the name of the annotation. If there is no additional
20714 information associated with this annotation, the name of the annotation
20715 is followed immediately by a newline. If there is additional
20716 information, the name of the annotation is followed by a space, the
20717 additional information, and a newline. The additional information
20718 cannot contain newline characters.
20720 Any output not beginning with a newline and two @samp{control-z}
20721 characters denotes literal output from @value{GDBN}. Currently there is
20722 no need for @value{GDBN} to output a newline followed by two
20723 @samp{control-z} characters, but if there was such a need, the
20724 annotations could be extended with an @samp{escape} annotation which
20725 means those three characters as output.
20727 The annotation @var{level}, which is specified using the
20728 @option{--annotate} command line option (@pxref{Mode Options}), controls
20729 how much information @value{GDBN} prints together with its prompt,
20730 values of expressions, source lines, and other types of output. Level 0
20731 is for no anntations, level 1 is for use when @value{GDBN} is run as a
20732 subprocess of @sc{gnu} Emacs, level 3 is the maximum annotation suitable
20733 for programs that control @value{GDBN}, and level 2 annotations have
20734 been made obsolete (@pxref{Limitations, , Limitations of the Annotation
20735 Interface, annotate, GDB's Obsolete Annotations}).
20738 @kindex set annotate
20739 @item set annotate @var{level}
20740 The @value{GDBN} command @code{set annotate} sets the level of
20741 annotations to the specified @var{level}.
20743 @item show annotate
20744 @kindex show annotate
20745 Show the current annotation level.
20748 This chapter describes level 3 annotations.
20750 A simple example of starting up @value{GDBN} with annotations is:
20753 $ @kbd{gdb --annotate=3}
20755 Copyright 2003 Free Software Foundation, Inc.
20756 GDB is free software, covered by the GNU General Public License,
20757 and you are welcome to change it and/or distribute copies of it
20758 under certain conditions.
20759 Type "show copying" to see the conditions.
20760 There is absolutely no warranty for GDB. Type "show warranty"
20762 This GDB was configured as "i386-pc-linux-gnu"
20773 Here @samp{quit} is input to @value{GDBN}; the rest is output from
20774 @value{GDBN}. The three lines beginning @samp{^Z^Z} (where @samp{^Z}
20775 denotes a @samp{control-z} character) are annotations; the rest is
20776 output from @value{GDBN}.
20779 @section Annotation for @value{GDBN} Input
20781 @cindex annotations for prompts
20782 When @value{GDBN} prompts for input, it annotates this fact so it is possible
20783 to know when to send output, when the output from a given command is
20786 Different kinds of input each have a different @dfn{input type}. Each
20787 input type has three annotations: a @code{pre-} annotation, which
20788 denotes the beginning of any prompt which is being output, a plain
20789 annotation, which denotes the end of the prompt, and then a @code{post-}
20790 annotation which denotes the end of any echo which may (or may not) be
20791 associated with the input. For example, the @code{prompt} input type
20792 features the following annotations:
20800 The input types are
20805 @findex post-prompt
20807 When @value{GDBN} is prompting for a command (the main @value{GDBN} prompt).
20809 @findex pre-commands
20811 @findex post-commands
20813 When @value{GDBN} prompts for a set of commands, like in the @code{commands}
20814 command. The annotations are repeated for each command which is input.
20816 @findex pre-overload-choice
20817 @findex overload-choice
20818 @findex post-overload-choice
20819 @item overload-choice
20820 When @value{GDBN} wants the user to select between various overloaded functions.
20826 When @value{GDBN} wants the user to confirm a potentially dangerous operation.
20828 @findex pre-prompt-for-continue
20829 @findex prompt-for-continue
20830 @findex post-prompt-for-continue
20831 @item prompt-for-continue
20832 When @value{GDBN} is asking the user to press return to continue. Note: Don't
20833 expect this to work well; instead use @code{set height 0} to disable
20834 prompting. This is because the counting of lines is buggy in the
20835 presence of annotations.
20840 @cindex annotations for errors, warnings and interrupts
20847 This annotation occurs right before @value{GDBN} responds to an interrupt.
20854 This annotation occurs right before @value{GDBN} responds to an error.
20856 Quit and error annotations indicate that any annotations which @value{GDBN} was
20857 in the middle of may end abruptly. For example, if a
20858 @code{value-history-begin} annotation is followed by a @code{error}, one
20859 cannot expect to receive the matching @code{value-history-end}. One
20860 cannot expect not to receive it either, however; an error annotation
20861 does not necessarily mean that @value{GDBN} is immediately returning all the way
20864 @findex error-begin
20865 A quit or error annotation may be preceded by
20871 Any output between that and the quit or error annotation is the error
20874 Warning messages are not yet annotated.
20875 @c If we want to change that, need to fix warning(), type_error(),
20876 @c range_error(), and possibly other places.
20879 @section Invalidation Notices
20881 @cindex annotations for invalidation messages
20882 The following annotations say that certain pieces of state may have
20886 @findex frames-invalid
20887 @item ^Z^Zframes-invalid
20889 The frames (for example, output from the @code{backtrace} command) may
20892 @findex breakpoints-invalid
20893 @item ^Z^Zbreakpoints-invalid
20895 The breakpoints may have changed. For example, the user just added or
20896 deleted a breakpoint.
20899 @node Annotations for Running
20900 @section Running the Program
20901 @cindex annotations for running programs
20905 When the program starts executing due to a @value{GDBN} command such as
20906 @code{step} or @code{continue},
20912 is output. When the program stops,
20918 is output. Before the @code{stopped} annotation, a variety of
20919 annotations describe how the program stopped.
20923 @item ^Z^Zexited @var{exit-status}
20924 The program exited, and @var{exit-status} is the exit status (zero for
20925 successful exit, otherwise nonzero).
20928 @findex signal-name
20929 @findex signal-name-end
20930 @findex signal-string
20931 @findex signal-string-end
20932 @item ^Z^Zsignalled
20933 The program exited with a signal. After the @code{^Z^Zsignalled}, the
20934 annotation continues:
20940 ^Z^Zsignal-name-end
20944 ^Z^Zsignal-string-end
20949 where @var{name} is the name of the signal, such as @code{SIGILL} or
20950 @code{SIGSEGV}, and @var{string} is the explanation of the signal, such
20951 as @code{Illegal Instruction} or @code{Segmentation fault}.
20952 @var{intro-text}, @var{middle-text}, and @var{end-text} are for the
20953 user's benefit and have no particular format.
20957 The syntax of this annotation is just like @code{signalled}, but @value{GDBN} is
20958 just saying that the program received the signal, not that it was
20959 terminated with it.
20962 @item ^Z^Zbreakpoint @var{number}
20963 The program hit breakpoint number @var{number}.
20966 @item ^Z^Zwatchpoint @var{number}
20967 The program hit watchpoint number @var{number}.
20970 @node Source Annotations
20971 @section Displaying Source
20972 @cindex annotations for source display
20975 The following annotation is used instead of displaying source code:
20978 ^Z^Zsource @var{filename}:@var{line}:@var{character}:@var{middle}:@var{addr}
20981 where @var{filename} is an absolute file name indicating which source
20982 file, @var{line} is the line number within that file (where 1 is the
20983 first line in the file), @var{character} is the character position
20984 within the file (where 0 is the first character in the file) (for most
20985 debug formats this will necessarily point to the beginning of a line),
20986 @var{middle} is @samp{middle} if @var{addr} is in the middle of the
20987 line, or @samp{beg} if @var{addr} is at the beginning of the line, and
20988 @var{addr} is the address in the target program associated with the
20989 source which is being displayed. @var{addr} is in the form @samp{0x}
20990 followed by one or more lowercase hex digits (note that this does not
20991 depend on the language).
20994 @chapter Reporting Bugs in @value{GDBN}
20995 @cindex bugs in @value{GDBN}
20996 @cindex reporting bugs in @value{GDBN}
20998 Your bug reports play an essential role in making @value{GDBN} reliable.
21000 Reporting a bug may help you by bringing a solution to your problem, or it
21001 may not. But in any case the principal function of a bug report is to help
21002 the entire community by making the next version of @value{GDBN} work better. Bug
21003 reports are your contribution to the maintenance of @value{GDBN}.
21005 In order for a bug report to serve its purpose, you must include the
21006 information that enables us to fix the bug.
21009 * Bug Criteria:: Have you found a bug?
21010 * Bug Reporting:: How to report bugs
21014 @section Have you found a bug?
21015 @cindex bug criteria
21017 If you are not sure whether you have found a bug, here are some guidelines:
21020 @cindex fatal signal
21021 @cindex debugger crash
21022 @cindex crash of debugger
21024 If the debugger gets a fatal signal, for any input whatever, that is a
21025 @value{GDBN} bug. Reliable debuggers never crash.
21027 @cindex error on valid input
21029 If @value{GDBN} produces an error message for valid input, that is a
21030 bug. (Note that if you're cross debugging, the problem may also be
21031 somewhere in the connection to the target.)
21033 @cindex invalid input
21035 If @value{GDBN} does not produce an error message for invalid input,
21036 that is a bug. However, you should note that your idea of
21037 ``invalid input'' might be our idea of ``an extension'' or ``support
21038 for traditional practice''.
21041 If you are an experienced user of debugging tools, your suggestions
21042 for improvement of @value{GDBN} are welcome in any case.
21045 @node Bug Reporting
21046 @section How to report bugs
21047 @cindex bug reports
21048 @cindex @value{GDBN} bugs, reporting
21050 A number of companies and individuals offer support for @sc{gnu} products.
21051 If you obtained @value{GDBN} from a support organization, we recommend you
21052 contact that organization first.
21054 You can find contact information for many support companies and
21055 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
21057 @c should add a web page ref...
21059 In any event, we also recommend that you submit bug reports for
21060 @value{GDBN}. The prefered method is to submit them directly using
21061 @uref{http://www.gnu.org/software/gdb/bugs/, @value{GDBN}'s Bugs web
21062 page}. Alternatively, the @email{bug-gdb@@gnu.org, e-mail gateway} can
21065 @strong{Do not send bug reports to @samp{info-gdb}, or to
21066 @samp{help-gdb}, or to any newsgroups.} Most users of @value{GDBN} do
21067 not want to receive bug reports. Those that do have arranged to receive
21070 The mailing list @samp{bug-gdb} has a newsgroup @samp{gnu.gdb.bug} which
21071 serves as a repeater. The mailing list and the newsgroup carry exactly
21072 the same messages. Often people think of posting bug reports to the
21073 newsgroup instead of mailing them. This appears to work, but it has one
21074 problem which can be crucial: a newsgroup posting often lacks a mail
21075 path back to the sender. Thus, if we need to ask for more information,
21076 we may be unable to reach you. For this reason, it is better to send
21077 bug reports to the mailing list.
21079 The fundamental principle of reporting bugs usefully is this:
21080 @strong{report all the facts}. If you are not sure whether to state a
21081 fact or leave it out, state it!
21083 Often people omit facts because they think they know what causes the
21084 problem and assume that some details do not matter. Thus, you might
21085 assume that the name of the variable you use in an example does not matter.
21086 Well, probably it does not, but one cannot be sure. Perhaps the bug is a
21087 stray memory reference which happens to fetch from the location where that
21088 name is stored in memory; perhaps, if the name were different, the contents
21089 of that location would fool the debugger into doing the right thing despite
21090 the bug. Play it safe and give a specific, complete example. That is the
21091 easiest thing for you to do, and the most helpful.
21093 Keep in mind that the purpose of a bug report is to enable us to fix the
21094 bug. It may be that the bug has been reported previously, but neither
21095 you nor we can know that unless your bug report is complete and
21098 Sometimes people give a few sketchy facts and ask, ``Does this ring a
21099 bell?'' Those bug reports are useless, and we urge everyone to
21100 @emph{refuse to respond to them} except to chide the sender to report
21103 To enable us to fix the bug, you should include all these things:
21107 The version of @value{GDBN}. @value{GDBN} announces it if you start
21108 with no arguments; you can also print it at any time using @code{show
21111 Without this, we will not know whether there is any point in looking for
21112 the bug in the current version of @value{GDBN}.
21115 The type of machine you are using, and the operating system name and
21119 What compiler (and its version) was used to compile @value{GDBN}---e.g.
21120 ``@value{GCC}--2.8.1''.
21123 What compiler (and its version) was used to compile the program you are
21124 debugging---e.g. ``@value{GCC}--2.8.1'', or ``HP92453-01 A.10.32.03 HP
21125 C Compiler''. For GCC, you can say @code{gcc --version} to get this
21126 information; for other compilers, see the documentation for those
21130 The command arguments you gave the compiler to compile your example and
21131 observe the bug. For example, did you use @samp{-O}? To guarantee
21132 you will not omit something important, list them all. A copy of the
21133 Makefile (or the output from make) is sufficient.
21135 If we were to try to guess the arguments, we would probably guess wrong
21136 and then we might not encounter the bug.
21139 A complete input script, and all necessary source files, that will
21143 A description of what behavior you observe that you believe is
21144 incorrect. For example, ``It gets a fatal signal.''
21146 Of course, if the bug is that @value{GDBN} gets a fatal signal, then we
21147 will certainly notice it. But if the bug is incorrect output, we might
21148 not notice unless it is glaringly wrong. You might as well not give us
21149 a chance to make a mistake.
21151 Even if the problem you experience is a fatal signal, you should still
21152 say so explicitly. Suppose something strange is going on, such as, your
21153 copy of @value{GDBN} is out of synch, or you have encountered a bug in
21154 the C library on your system. (This has happened!) Your copy might
21155 crash and ours would not. If you told us to expect a crash, then when
21156 ours fails to crash, we would know that the bug was not happening for
21157 us. If you had not told us to expect a crash, then we would not be able
21158 to draw any conclusion from our observations.
21161 @cindex recording a session script
21162 To collect all this information, you can use a session recording program
21163 such as @command{script}, which is available on many Unix systems.
21164 Just run your @value{GDBN} session inside @command{script} and then
21165 include the @file{typescript} file with your bug report.
21167 Another way to record a @value{GDBN} session is to run @value{GDBN}
21168 inside Emacs and then save the entire buffer to a file.
21171 If you wish to suggest changes to the @value{GDBN} source, send us context
21172 diffs. If you even discuss something in the @value{GDBN} source, refer to
21173 it by context, not by line number.
21175 The line numbers in our development sources will not match those in your
21176 sources. Your line numbers would convey no useful information to us.
21180 Here are some things that are not necessary:
21184 A description of the envelope of the bug.
21186 Often people who encounter a bug spend a lot of time investigating
21187 which changes to the input file will make the bug go away and which
21188 changes will not affect it.
21190 This is often time consuming and not very useful, because the way we
21191 will find the bug is by running a single example under the debugger
21192 with breakpoints, not by pure deduction from a series of examples.
21193 We recommend that you save your time for something else.
21195 Of course, if you can find a simpler example to report @emph{instead}
21196 of the original one, that is a convenience for us. Errors in the
21197 output will be easier to spot, running under the debugger will take
21198 less time, and so on.
21200 However, simplification is not vital; if you do not want to do this,
21201 report the bug anyway and send us the entire test case you used.
21204 A patch for the bug.
21206 A patch for the bug does help us if it is a good one. But do not omit
21207 the necessary information, such as the test case, on the assumption that
21208 a patch is all we need. We might see problems with your patch and decide
21209 to fix the problem another way, or we might not understand it at all.
21211 Sometimes with a program as complicated as @value{GDBN} it is very hard to
21212 construct an example that will make the program follow a certain path
21213 through the code. If you do not send us the example, we will not be able
21214 to construct one, so we will not be able to verify that the bug is fixed.
21216 And if we cannot understand what bug you are trying to fix, or why your
21217 patch should be an improvement, we will not install it. A test case will
21218 help us to understand.
21221 A guess about what the bug is or what it depends on.
21223 Such guesses are usually wrong. Even we cannot guess right about such
21224 things without first using the debugger to find the facts.
21227 @c The readline documentation is distributed with the readline code
21228 @c and consists of the two following files:
21230 @c inc-hist.texinfo
21231 @c Use -I with makeinfo to point to the appropriate directory,
21232 @c environment var TEXINPUTS with TeX.
21233 @include rluser.texinfo
21234 @include inc-hist.texinfo
21237 @node Formatting Documentation
21238 @appendix Formatting Documentation
21240 @cindex @value{GDBN} reference card
21241 @cindex reference card
21242 The @value{GDBN} 4 release includes an already-formatted reference card, ready
21243 for printing with PostScript or Ghostscript, in the @file{gdb}
21244 subdirectory of the main source directory@footnote{In
21245 @file{gdb-@value{GDBVN}/gdb/refcard.ps} of the version @value{GDBVN}
21246 release.}. If you can use PostScript or Ghostscript with your printer,
21247 you can print the reference card immediately with @file{refcard.ps}.
21249 The release also includes the source for the reference card. You
21250 can format it, using @TeX{}, by typing:
21256 The @value{GDBN} reference card is designed to print in @dfn{landscape}
21257 mode on US ``letter'' size paper;
21258 that is, on a sheet 11 inches wide by 8.5 inches
21259 high. You will need to specify this form of printing as an option to
21260 your @sc{dvi} output program.
21262 @cindex documentation
21264 All the documentation for @value{GDBN} comes as part of the machine-readable
21265 distribution. The documentation is written in Texinfo format, which is
21266 a documentation system that uses a single source file to produce both
21267 on-line information and a printed manual. You can use one of the Info
21268 formatting commands to create the on-line version of the documentation
21269 and @TeX{} (or @code{texi2roff}) to typeset the printed version.
21271 @value{GDBN} includes an already formatted copy of the on-line Info
21272 version of this manual in the @file{gdb} subdirectory. The main Info
21273 file is @file{gdb-@value{GDBVN}/gdb/gdb.info}, and it refers to
21274 subordinate files matching @samp{gdb.info*} in the same directory. If
21275 necessary, you can print out these files, or read them with any editor;
21276 but they are easier to read using the @code{info} subsystem in @sc{gnu}
21277 Emacs or the standalone @code{info} program, available as part of the
21278 @sc{gnu} Texinfo distribution.
21280 If you want to format these Info files yourself, you need one of the
21281 Info formatting programs, such as @code{texinfo-format-buffer} or
21284 If you have @code{makeinfo} installed, and are in the top level
21285 @value{GDBN} source directory (@file{gdb-@value{GDBVN}}, in the case of
21286 version @value{GDBVN}), you can make the Info file by typing:
21293 If you want to typeset and print copies of this manual, you need @TeX{},
21294 a program to print its @sc{dvi} output files, and @file{texinfo.tex}, the
21295 Texinfo definitions file.
21297 @TeX{} is a typesetting program; it does not print files directly, but
21298 produces output files called @sc{dvi} files. To print a typeset
21299 document, you need a program to print @sc{dvi} files. If your system
21300 has @TeX{} installed, chances are it has such a program. The precise
21301 command to use depends on your system; @kbd{lpr -d} is common; another
21302 (for PostScript devices) is @kbd{dvips}. The @sc{dvi} print command may
21303 require a file name without any extension or a @samp{.dvi} extension.
21305 @TeX{} also requires a macro definitions file called
21306 @file{texinfo.tex}. This file tells @TeX{} how to typeset a document
21307 written in Texinfo format. On its own, @TeX{} cannot either read or
21308 typeset a Texinfo file. @file{texinfo.tex} is distributed with GDB
21309 and is located in the @file{gdb-@var{version-number}/texinfo}
21312 If you have @TeX{} and a @sc{dvi} printer program installed, you can
21313 typeset and print this manual. First switch to the the @file{gdb}
21314 subdirectory of the main source directory (for example, to
21315 @file{gdb-@value{GDBVN}/gdb}) and type:
21321 Then give @file{gdb.dvi} to your @sc{dvi} printing program.
21323 @node Installing GDB
21324 @appendix Installing @value{GDBN}
21325 @cindex configuring @value{GDBN}
21326 @cindex installation
21327 @cindex configuring @value{GDBN}, and source tree subdirectories
21329 @value{GDBN} comes with a @code{configure} script that automates the process
21330 of preparing @value{GDBN} for installation; you can then use @code{make} to
21331 build the @code{gdb} program.
21333 @c irrelevant in info file; it's as current as the code it lives with.
21334 @footnote{If you have a more recent version of @value{GDBN} than @value{GDBVN},
21335 look at the @file{README} file in the sources; we may have improved the
21336 installation procedures since publishing this manual.}
21339 The @value{GDBN} distribution includes all the source code you need for
21340 @value{GDBN} in a single directory, whose name is usually composed by
21341 appending the version number to @samp{gdb}.
21343 For example, the @value{GDBN} version @value{GDBVN} distribution is in the
21344 @file{gdb-@value{GDBVN}} directory. That directory contains:
21347 @item gdb-@value{GDBVN}/configure @r{(and supporting files)}
21348 script for configuring @value{GDBN} and all its supporting libraries
21350 @item gdb-@value{GDBVN}/gdb
21351 the source specific to @value{GDBN} itself
21353 @item gdb-@value{GDBVN}/bfd
21354 source for the Binary File Descriptor library
21356 @item gdb-@value{GDBVN}/include
21357 @sc{gnu} include files
21359 @item gdb-@value{GDBVN}/libiberty
21360 source for the @samp{-liberty} free software library
21362 @item gdb-@value{GDBVN}/opcodes
21363 source for the library of opcode tables and disassemblers
21365 @item gdb-@value{GDBVN}/readline
21366 source for the @sc{gnu} command-line interface
21368 @item gdb-@value{GDBVN}/glob
21369 source for the @sc{gnu} filename pattern-matching subroutine
21371 @item gdb-@value{GDBVN}/mmalloc
21372 source for the @sc{gnu} memory-mapped malloc package
21375 The simplest way to configure and build @value{GDBN} is to run @code{configure}
21376 from the @file{gdb-@var{version-number}} source directory, which in
21377 this example is the @file{gdb-@value{GDBVN}} directory.
21379 First switch to the @file{gdb-@var{version-number}} source directory
21380 if you are not already in it; then run @code{configure}. Pass the
21381 identifier for the platform on which @value{GDBN} will run as an
21387 cd gdb-@value{GDBVN}
21388 ./configure @var{host}
21393 where @var{host} is an identifier such as @samp{sun4} or
21394 @samp{decstation}, that identifies the platform where @value{GDBN} will run.
21395 (You can often leave off @var{host}; @code{configure} tries to guess the
21396 correct value by examining your system.)
21398 Running @samp{configure @var{host}} and then running @code{make} builds the
21399 @file{bfd}, @file{readline}, @file{mmalloc}, and @file{libiberty}
21400 libraries, then @code{gdb} itself. The configured source files, and the
21401 binaries, are left in the corresponding source directories.
21404 @code{configure} is a Bourne-shell (@code{/bin/sh}) script; if your
21405 system does not recognize this automatically when you run a different
21406 shell, you may need to run @code{sh} on it explicitly:
21409 sh configure @var{host}
21412 If you run @code{configure} from a directory that contains source
21413 directories for multiple libraries or programs, such as the
21414 @file{gdb-@value{GDBVN}} source directory for version @value{GDBVN}, @code{configure}
21415 creates configuration files for every directory level underneath (unless
21416 you tell it not to, with the @samp{--norecursion} option).
21418 You should run the @code{configure} script from the top directory in the
21419 source tree, the @file{gdb-@var{version-number}} directory. If you run
21420 @code{configure} from one of the subdirectories, you will configure only
21421 that subdirectory. That is usually not what you want. In particular,
21422 if you run the first @code{configure} from the @file{gdb} subdirectory
21423 of the @file{gdb-@var{version-number}} directory, you will omit the
21424 configuration of @file{bfd}, @file{readline}, and other sibling
21425 directories of the @file{gdb} subdirectory. This leads to build errors
21426 about missing include files such as @file{bfd/bfd.h}.
21428 You can install @code{@value{GDBP}} anywhere; it has no hardwired paths.
21429 However, you should make sure that the shell on your path (named by
21430 the @samp{SHELL} environment variable) is publicly readable. Remember
21431 that @value{GDBN} uses the shell to start your program---some systems refuse to
21432 let @value{GDBN} debug child processes whose programs are not readable.
21435 * Separate Objdir:: Compiling @value{GDBN} in another directory
21436 * Config Names:: Specifying names for hosts and targets
21437 * Configure Options:: Summary of options for configure
21440 @node Separate Objdir
21441 @section Compiling @value{GDBN} in another directory
21443 If you want to run @value{GDBN} versions for several host or target machines,
21444 you need a different @code{gdb} compiled for each combination of
21445 host and target. @code{configure} is designed to make this easy by
21446 allowing you to generate each configuration in a separate subdirectory,
21447 rather than in the source directory. If your @code{make} program
21448 handles the @samp{VPATH} feature (@sc{gnu} @code{make} does), running
21449 @code{make} in each of these directories builds the @code{gdb}
21450 program specified there.
21452 To build @code{gdb} in a separate directory, run @code{configure}
21453 with the @samp{--srcdir} option to specify where to find the source.
21454 (You also need to specify a path to find @code{configure}
21455 itself from your working directory. If the path to @code{configure}
21456 would be the same as the argument to @samp{--srcdir}, you can leave out
21457 the @samp{--srcdir} option; it is assumed.)
21459 For example, with version @value{GDBVN}, you can build @value{GDBN} in a
21460 separate directory for a Sun 4 like this:
21464 cd gdb-@value{GDBVN}
21467 ../gdb-@value{GDBVN}/configure sun4
21472 When @code{configure} builds a configuration using a remote source
21473 directory, it creates a tree for the binaries with the same structure
21474 (and using the same names) as the tree under the source directory. In
21475 the example, you'd find the Sun 4 library @file{libiberty.a} in the
21476 directory @file{gdb-sun4/libiberty}, and @value{GDBN} itself in
21477 @file{gdb-sun4/gdb}.
21479 Make sure that your path to the @file{configure} script has just one
21480 instance of @file{gdb} in it. If your path to @file{configure} looks
21481 like @file{../gdb-@value{GDBVN}/gdb/configure}, you are configuring only
21482 one subdirectory of @value{GDBN}, not the whole package. This leads to
21483 build errors about missing include files such as @file{bfd/bfd.h}.
21485 One popular reason to build several @value{GDBN} configurations in separate
21486 directories is to configure @value{GDBN} for cross-compiling (where
21487 @value{GDBN} runs on one machine---the @dfn{host}---while debugging
21488 programs that run on another machine---the @dfn{target}).
21489 You specify a cross-debugging target by
21490 giving the @samp{--target=@var{target}} option to @code{configure}.
21492 When you run @code{make} to build a program or library, you must run
21493 it in a configured directory---whatever directory you were in when you
21494 called @code{configure} (or one of its subdirectories).
21496 The @code{Makefile} that @code{configure} generates in each source
21497 directory also runs recursively. If you type @code{make} in a source
21498 directory such as @file{gdb-@value{GDBVN}} (or in a separate configured
21499 directory configured with @samp{--srcdir=@var{dirname}/gdb-@value{GDBVN}}), you
21500 will build all the required libraries, and then build GDB.
21502 When you have multiple hosts or targets configured in separate
21503 directories, you can run @code{make} on them in parallel (for example,
21504 if they are NFS-mounted on each of the hosts); they will not interfere
21508 @section Specifying names for hosts and targets
21510 The specifications used for hosts and targets in the @code{configure}
21511 script are based on a three-part naming scheme, but some short predefined
21512 aliases are also supported. The full naming scheme encodes three pieces
21513 of information in the following pattern:
21516 @var{architecture}-@var{vendor}-@var{os}
21519 For example, you can use the alias @code{sun4} as a @var{host} argument,
21520 or as the value for @var{target} in a @code{--target=@var{target}}
21521 option. The equivalent full name is @samp{sparc-sun-sunos4}.
21523 The @code{configure} script accompanying @value{GDBN} does not provide
21524 any query facility to list all supported host and target names or
21525 aliases. @code{configure} calls the Bourne shell script
21526 @code{config.sub} to map abbreviations to full names; you can read the
21527 script, if you wish, or you can use it to test your guesses on
21528 abbreviations---for example:
21531 % sh config.sub i386-linux
21533 % sh config.sub alpha-linux
21534 alpha-unknown-linux-gnu
21535 % sh config.sub hp9k700
21537 % sh config.sub sun4
21538 sparc-sun-sunos4.1.1
21539 % sh config.sub sun3
21540 m68k-sun-sunos4.1.1
21541 % sh config.sub i986v
21542 Invalid configuration `i986v': machine `i986v' not recognized
21546 @code{config.sub} is also distributed in the @value{GDBN} source
21547 directory (@file{gdb-@value{GDBVN}}, for version @value{GDBVN}).
21549 @node Configure Options
21550 @section @code{configure} options
21552 Here is a summary of the @code{configure} options and arguments that
21553 are most often useful for building @value{GDBN}. @code{configure} also has
21554 several other options not listed here. @inforef{What Configure
21555 Does,,configure.info}, for a full explanation of @code{configure}.
21558 configure @r{[}--help@r{]}
21559 @r{[}--prefix=@var{dir}@r{]}
21560 @r{[}--exec-prefix=@var{dir}@r{]}
21561 @r{[}--srcdir=@var{dirname}@r{]}
21562 @r{[}--norecursion@r{]} @r{[}--rm@r{]}
21563 @r{[}--target=@var{target}@r{]}
21568 You may introduce options with a single @samp{-} rather than
21569 @samp{--} if you prefer; but you may abbreviate option names if you use
21574 Display a quick summary of how to invoke @code{configure}.
21576 @item --prefix=@var{dir}
21577 Configure the source to install programs and files under directory
21580 @item --exec-prefix=@var{dir}
21581 Configure the source to install programs under directory
21584 @c avoid splitting the warning from the explanation:
21586 @item --srcdir=@var{dirname}
21587 @strong{Warning: using this option requires @sc{gnu} @code{make}, or another
21588 @code{make} that implements the @code{VPATH} feature.}@*
21589 Use this option to make configurations in directories separate from the
21590 @value{GDBN} source directories. Among other things, you can use this to
21591 build (or maintain) several configurations simultaneously, in separate
21592 directories. @code{configure} writes configuration specific files in
21593 the current directory, but arranges for them to use the source in the
21594 directory @var{dirname}. @code{configure} creates directories under
21595 the working directory in parallel to the source directories below
21598 @item --norecursion
21599 Configure only the directory level where @code{configure} is executed; do not
21600 propagate configuration to subdirectories.
21602 @item --target=@var{target}
21603 Configure @value{GDBN} for cross-debugging programs running on the specified
21604 @var{target}. Without this option, @value{GDBN} is configured to debug
21605 programs that run on the same machine (@var{host}) as @value{GDBN} itself.
21607 There is no convenient way to generate a list of all available targets.
21609 @item @var{host} @dots{}
21610 Configure @value{GDBN} to run on the specified @var{host}.
21612 There is no convenient way to generate a list of all available hosts.
21615 There are many other options available as well, but they are generally
21616 needed for special purposes only.
21618 @node Maintenance Commands
21619 @appendix Maintenance Commands
21620 @cindex maintenance commands
21621 @cindex internal commands
21623 In addition to commands intended for @value{GDBN} users, @value{GDBN}
21624 includes a number of commands intended for @value{GDBN} developers,
21625 that are not documented elsewhere in this manual. These commands are
21626 provided here for reference. (For commands that turn on debugging
21627 messages, see @ref{Debugging Output}.)
21630 @kindex maint agent
21631 @item maint agent @var{expression}
21632 Translate the given @var{expression} into remote agent bytecodes.
21633 This command is useful for debugging the Agent Expression mechanism
21634 (@pxref{Agent Expressions}).
21636 @kindex maint info breakpoints
21637 @item @anchor{maint info breakpoints}maint info breakpoints
21638 Using the same format as @samp{info breakpoints}, display both the
21639 breakpoints you've set explicitly, and those @value{GDBN} is using for
21640 internal purposes. Internal breakpoints are shown with negative
21641 breakpoint numbers. The type column identifies what kind of breakpoint
21646 Normal, explicitly set breakpoint.
21649 Normal, explicitly set watchpoint.
21652 Internal breakpoint, used to handle correctly stepping through
21653 @code{longjmp} calls.
21655 @item longjmp resume
21656 Internal breakpoint at the target of a @code{longjmp}.
21659 Temporary internal breakpoint used by the @value{GDBN} @code{until} command.
21662 Temporary internal breakpoint used by the @value{GDBN} @code{finish} command.
21665 Shared library events.
21669 @kindex maint check-symtabs
21670 @item maint check-symtabs
21671 Check the consistency of psymtabs and symtabs.
21673 @kindex maint cplus first_component
21674 @item maint cplus first_component @var{name}
21675 Print the first C@t{++} class/namespace component of @var{name}.
21677 @kindex maint cplus namespace
21678 @item maint cplus namespace
21679 Print the list of possible C@t{++} namespaces.
21681 @kindex maint demangle
21682 @item maint demangle @var{name}
21683 Demangle a C@t{++} or Objective-C manled @var{name}.
21685 @kindex maint deprecate
21686 @kindex maint undeprecate
21687 @cindex deprecated commands
21688 @item maint deprecate @var{command} @r{[}@var{replacement}@r{]}
21689 @itemx maint undeprecate @var{command}
21690 Deprecate or undeprecate the named @var{command}. Deprecated commands
21691 cause @value{GDBN} to issue a warning when you use them. The optional
21692 argument @var{replacement} says which newer command should be used in
21693 favor of the deprecated one; if it is given, @value{GDBN} will mention
21694 the replacement as part of the warning.
21696 @kindex maint dump-me
21697 @item maint dump-me
21698 @cindex @code{SIGQUIT} signal, dump core of @value{GDBN}
21699 Cause a fatal signal in the debugger and force it to dump its core.
21700 This is supported only on systems which support aborting a program
21701 with the @code{SIGQUIT} signal.
21703 @kindex maint internal-error
21704 @kindex maint internal-warning
21705 @item maint internal-error @r{[}@var{message-text}@r{]}
21706 @itemx maint internal-warning @r{[}@var{message-text}@r{]}
21707 Cause @value{GDBN} to call the internal function @code{internal_error}
21708 or @code{internal_warning} and hence behave as though an internal error
21709 or internal warning has been detected. In addition to reporting the
21710 internal problem, these functions give the user the opportunity to
21711 either quit @value{GDBN} or create a core file of the current
21712 @value{GDBN} session.
21714 These commands take an optional parameter @var{message-text} that is
21715 used as the text of the error or warning message.
21717 Here's an example of using @code{indernal-error}:
21720 (@value{GDBP}) @kbd{maint internal-error testing, 1, 2}
21721 @dots{}/maint.c:121: internal-error: testing, 1, 2
21722 A problem internal to GDB has been detected. Further
21723 debugging may prove unreliable.
21724 Quit this debugging session? (y or n) @kbd{n}
21725 Create a core file? (y or n) @kbd{n}
21729 @kindex maint packet
21730 @item maint packet @var{text}
21731 If @value{GDBN} is talking to an inferior via the serial protocol,
21732 then this command sends the string @var{text} to the inferior, and
21733 displays the response packet. @value{GDBN} supplies the initial
21734 @samp{$} character, the terminating @samp{#} character, and the
21737 @kindex maint print architecture
21738 @item maint print architecture @r{[}@var{file}@r{]}
21739 Print the entire architecture configuration. The optional argument
21740 @var{file} names the file where the output goes.
21742 @kindex maint print dummy-frames
21743 @item maint print dummy-frames
21744 Prints the contents of @value{GDBN}'s internal dummy-frame stack.
21747 (@value{GDBP}) @kbd{b add}
21749 (@value{GDBP}) @kbd{print add(2,3)}
21750 Breakpoint 2, add (a=2, b=3) at @dots{}
21752 The program being debugged stopped while in a function called from GDB.
21754 (@value{GDBP}) @kbd{maint print dummy-frames}
21755 0x1a57c80: pc=0x01014068 fp=0x0200bddc sp=0x0200bdd6
21756 top=0x0200bdd4 id=@{stack=0x200bddc,code=0x101405c@}
21757 call_lo=0x01014000 call_hi=0x01014001
21761 Takes an optional file parameter.
21763 @kindex maint print registers
21764 @kindex maint print raw-registers
21765 @kindex maint print cooked-registers
21766 @kindex maint print register-groups
21767 @item maint print registers @r{[}@var{file}@r{]}
21768 @itemx maint print raw-registers @r{[}@var{file}@r{]}
21769 @itemx maint print cooked-registers @r{[}@var{file}@r{]}
21770 @itemx maint print register-groups @r{[}@var{file}@r{]}
21771 Print @value{GDBN}'s internal register data structures.
21773 The command @code{maint print raw-registers} includes the contents of
21774 the raw register cache; the command @code{maint print cooked-registers}
21775 includes the (cooked) value of all registers; and the command
21776 @code{maint print register-groups} includes the groups that each
21777 register is a member of. @xref{Registers,, Registers, gdbint,
21778 @value{GDBN} Internals}.
21780 These commands take an optional parameter, a file name to which to
21781 write the information.
21783 @kindex maint print reggroups
21784 @item maint print reggroups @r{[}@var{file}@r{]}
21785 Print @value{GDBN}'s internal register group data structures. The
21786 optional argument @var{file} tells to what file to write the
21789 The register groups info looks like this:
21792 (@value{GDBP}) @kbd{maint print reggroups}
21805 This command forces @value{GDBN} to flush its internal register cache.
21807 @kindex maint print objfiles
21808 @cindex info for known object files
21809 @item maint print objfiles
21810 Print a dump of all known object files. For each object file, this
21811 command prints its name, address in memory, and all of its psymtabs
21814 @kindex maint print statistics
21815 @cindex bcache statistics
21816 @item maint print statistics
21817 This command prints, for each object file in the program, various data
21818 about that object file followed by the byte cache (@dfn{bcache})
21819 statistics for the object file. The objfile data includes the number
21820 of minimal, partical, full, and stabs symbols, the number of types
21821 defined by the objfile, the number of as yet unexpanded psym tables,
21822 the number of line tables and string tables, and the amount of memory
21823 used by the various tables. The bcache statistics include the counts,
21824 sizes, and counts of duplicates of all and unique objects, max,
21825 average, and median entry size, total memory used and its overhead and
21826 savings, and various measures of the hash table size and chain
21829 @kindex maint print type
21830 @cindex type chain of a data type
21831 @item maint print type @var{expr}
21832 Print the type chain for a type specified by @var{expr}. The argument
21833 can be either a type name or a symbol. If it is a symbol, the type of
21834 that symbol is described. The type chain produced by this command is
21835 a recursive definition of the data type as stored in @value{GDBN}'s
21836 data structures, including its flags and contained types.
21838 @kindex maint set dwarf2 max-cache-age
21839 @kindex maint show dwarf2 max-cache-age
21840 @item maint set dwarf2 max-cache-age
21841 @itemx maint show dwarf2 max-cache-age
21842 Control the DWARF 2 compilation unit cache.
21844 @cindex DWARF 2 compilation units cache
21845 In object files with inter-compilation-unit references, such as those
21846 produced by the GCC option @samp{-feliminate-dwarf2-dups}, the DWARF 2
21847 reader needs to frequently refer to previously read compilation units.
21848 This setting controls how long a compilation unit will remain in the
21849 cache if it is not referenced. A higher limit means that cached
21850 compilation units will be stored in memory longer, and more total
21851 memory will be used. Setting it to zero disables caching, which will
21852 slow down @value{GDBN} startup, but reduce memory consumption.
21854 @kindex maint set profile
21855 @kindex maint show profile
21856 @cindex profiling GDB
21857 @item maint set profile
21858 @itemx maint show profile
21859 Control profiling of @value{GDBN}.
21861 Profiling will be disabled until you use the @samp{maint set profile}
21862 command to enable it. When you enable profiling, the system will begin
21863 collecting timing and execution count data; when you disable profiling or
21864 exit @value{GDBN}, the results will be written to a log file. Remember that
21865 if you use profiling, @value{GDBN} will overwrite the profiling log file
21866 (often called @file{gmon.out}). If you have a record of important profiling
21867 data in a @file{gmon.out} file, be sure to move it to a safe location.
21869 Configuring with @samp{--enable-profiling} arranges for @value{GDBN} to be
21870 compiled with the @samp{-pg} compiler option.
21872 @kindex maint show-debug-regs
21873 @cindex x86 hardware debug registers
21874 @item maint show-debug-regs
21875 Control whether to show variables that mirror the x86 hardware debug
21876 registers. Use @code{ON} to enable, @code{OFF} to disable. If
21877 enabled, the debug registers values are shown when GDB inserts or
21878 removes a hardware breakpoint or watchpoint, and when the inferior
21879 triggers a hardware-assisted breakpoint or watchpoint.
21881 @kindex maint space
21882 @cindex memory used by commands
21884 Control whether to display memory usage for each command. If set to a
21885 nonzero value, @value{GDBN} will display how much memory each command
21886 took, following the command's own output. This can also be requested
21887 by invoking @value{GDBN} with the @option{--statistics} command-line
21888 switch (@pxref{Mode Options}).
21891 @cindex time of command execution
21893 Control whether to display the execution time for each command. If
21894 set to a nonzero value, @value{GDBN} will display how much time it
21895 took to execute each command, following the command's own output.
21896 This can also be requested by invoking @value{GDBN} with the
21897 @option{--statistics} command-line switch (@pxref{Mode Options}).
21899 @kindex maint translate-address
21900 @item maint translate-address @r{[}@var{section}@r{]} @var{addr}
21901 Find the symbol stored at the location specified by the address
21902 @var{addr} and an optional section name @var{section}. If found,
21903 @value{GDBN} prints the name of the closest symbol and an offset from
21904 the symbol's location to the specified address. This is similar to
21905 the @code{info address} command (@pxref{Symbols}), except that this
21906 command also allows to find symbols in other sections.
21910 The following command is useful for non-interactive invocations of
21911 @value{GDBN}, such as in the test suite.
21914 @item set watchdog @var{nsec}
21915 @kindex set watchdog
21916 @cindex watchdog timer
21917 @cindex timeout for commands
21918 Set the maximum number of seconds @value{GDBN} will wait for the
21919 target operation to finish. If this time expires, @value{GDBN}
21920 reports and error and the command is aborted.
21922 @item show watchdog
21923 Show the current setting of the target wait timeout.
21926 @node Remote Protocol
21927 @appendix @value{GDBN} Remote Serial Protocol
21932 * Stop Reply Packets::
21933 * General Query Packets::
21934 * Register Packet Format::
21936 * File-I/O remote protocol extension::
21942 There may be occasions when you need to know something about the
21943 protocol---for example, if there is only one serial port to your target
21944 machine, you might want your program to do something special if it
21945 recognizes a packet meant for @value{GDBN}.
21947 In the examples below, @samp{->} and @samp{<-} are used to indicate
21948 transmitted and received data respectfully.
21950 @cindex protocol, @value{GDBN} remote serial
21951 @cindex serial protocol, @value{GDBN} remote
21952 @cindex remote serial protocol
21953 All @value{GDBN} commands and responses (other than acknowledgments) are
21954 sent as a @var{packet}. A @var{packet} is introduced with the character
21955 @samp{$}, the actual @var{packet-data}, and the terminating character
21956 @samp{#} followed by a two-digit @var{checksum}:
21959 @code{$}@var{packet-data}@code{#}@var{checksum}
21963 @cindex checksum, for @value{GDBN} remote
21965 The two-digit @var{checksum} is computed as the modulo 256 sum of all
21966 characters between the leading @samp{$} and the trailing @samp{#} (an
21967 eight bit unsigned checksum).
21969 Implementors should note that prior to @value{GDBN} 5.0 the protocol
21970 specification also included an optional two-digit @var{sequence-id}:
21973 @code{$}@var{sequence-id}@code{:}@var{packet-data}@code{#}@var{checksum}
21976 @cindex sequence-id, for @value{GDBN} remote
21978 That @var{sequence-id} was appended to the acknowledgment. @value{GDBN}
21979 has never output @var{sequence-id}s. Stubs that handle packets added
21980 since @value{GDBN} 5.0 must not accept @var{sequence-id}.
21982 @cindex acknowledgment, for @value{GDBN} remote
21983 When either the host or the target machine receives a packet, the first
21984 response expected is an acknowledgment: either @samp{+} (to indicate
21985 the package was received correctly) or @samp{-} (to request
21989 -> @code{$}@var{packet-data}@code{#}@var{checksum}
21994 The host (@value{GDBN}) sends @var{command}s, and the target (the
21995 debugging stub incorporated in your program) sends a @var{response}. In
21996 the case of step and continue @var{command}s, the response is only sent
21997 when the operation has completed (the target has again stopped).
21999 @var{packet-data} consists of a sequence of characters with the
22000 exception of @samp{#} and @samp{$} (see @samp{X} packet for additional
22003 Fields within the packet should be separated using @samp{,} @samp{;} or
22004 @cindex remote protocol, field separator
22005 @samp{:}. Except where otherwise noted all numbers are represented in
22006 @sc{hex} with leading zeros suppressed.
22008 Implementors should note that prior to @value{GDBN} 5.0, the character
22009 @samp{:} could not appear as the third character in a packet (as it
22010 would potentially conflict with the @var{sequence-id}).
22012 Response @var{data} can be run-length encoded to save space. A @samp{*}
22013 means that the next character is an @sc{ascii} encoding giving a repeat count
22014 which stands for that many repetitions of the character preceding the
22015 @samp{*}. The encoding is @code{n+29}, yielding a printable character
22016 where @code{n >=3} (which is where rle starts to win). The printable
22017 characters @samp{$}, @samp{#}, @samp{+} and @samp{-} or with a numeric
22018 value greater than 126 should not be used.
22025 means the same as "0000".
22027 The error response returned for some packets includes a two character
22028 error number. That number is not well defined.
22030 For any @var{command} not supported by the stub, an empty response
22031 (@samp{$#00}) should be returned. That way it is possible to extend the
22032 protocol. A newer @value{GDBN} can tell if a packet is supported based
22035 A stub is required to support the @samp{g}, @samp{G}, @samp{m}, @samp{M},
22036 @samp{c}, and @samp{s} @var{command}s. All other @var{command}s are
22042 The following table provides a complete list of all currently defined
22043 @var{command}s and their corresponding response @var{data}.
22044 @xref{File-I/O remote protocol extension}, for details about the File
22045 I/O extension of the remote protocol.
22049 @item @code{!} --- extended mode
22050 @cindex @code{!} packet
22052 Enable extended mode. In extended mode, the remote server is made
22053 persistent. The @samp{R} packet is used to restart the program being
22059 The remote target both supports and has enabled extended mode.
22062 @item @code{?} --- last signal
22063 @cindex @code{?} packet
22065 Indicate the reason the target halted. The reply is the same as for
22069 @xref{Stop Reply Packets}, for the reply specifications.
22071 @item @code{a} --- reserved
22073 Reserved for future use.
22075 @item @code{A}@var{arglen}@code{,}@var{argnum}@code{,}@var{arg}@code{,@dots{}} --- set program arguments @strong{(reserved)}
22076 @cindex @code{A} packet
22078 Initialized @samp{argv[]} array passed into program. @var{arglen}
22079 specifies the number of bytes in the hex encoded byte stream @var{arg}.
22080 See @code{gdbserver} for more details.
22088 @item @code{b}@var{baud} --- set baud @strong{(deprecated)}
22089 @cindex @code{b} packet
22091 Change the serial line speed to @var{baud}.
22093 JTC: @emph{When does the transport layer state change? When it's
22094 received, or after the ACK is transmitted. In either case, there are
22095 problems if the command or the acknowledgment packet is dropped.}
22097 Stan: @emph{If people really wanted to add something like this, and get
22098 it working for the first time, they ought to modify ser-unix.c to send
22099 some kind of out-of-band message to a specially-setup stub and have the
22100 switch happen "in between" packets, so that from remote protocol's point
22101 of view, nothing actually happened.}
22103 @item @code{B}@var{addr},@var{mode} --- set breakpoint @strong{(deprecated)}
22104 @cindex @code{B} packet
22106 Set (@var{mode} is @samp{S}) or clear (@var{mode} is @samp{C}) a
22107 breakpoint at @var{addr}.
22109 This packet has been replaced by the @samp{Z} and @samp{z} packets
22110 (@pxref{insert breakpoint or watchpoint packet}).
22112 @item @code{c}@var{addr} --- continue
22113 @cindex @code{c} packet
22115 @var{addr} is address to resume. If @var{addr} is omitted, resume at
22119 @xref{Stop Reply Packets}, for the reply specifications.
22121 @item @code{C}@var{sig}@code{;}@var{addr} --- continue with signal
22122 @cindex @code{C} packet
22124 Continue with signal @var{sig} (hex signal number). If
22125 @code{;}@var{addr} is omitted, resume at same address.
22128 @xref{Stop Reply Packets}, for the reply specifications.
22130 @item @code{d} --- toggle debug @strong{(deprecated)}
22131 @cindex @code{d} packet
22135 @item @code{D} --- detach
22136 @cindex @code{D} packet
22138 Detach @value{GDBN} from the remote system. Sent to the remote target
22139 before @value{GDBN} disconnects via the @code{detach} command.
22149 @item @code{e} --- reserved
22151 Reserved for future use.
22153 @item @code{E} --- reserved
22155 Reserved for future use.
22157 @item @code{f} --- reserved
22159 Reserved for future use.
22161 @item @code{F}@var{RC}@code{,}@var{EE}@code{,}@var{CF}@code{;}@var{XX} --- Reply to target's F packet.
22162 @cindex @code{F} packet
22164 This packet is send by @value{GDBN} as reply to a @code{F} request packet
22165 sent by the target. This is part of the File-I/O protocol extension.
22166 @xref{File-I/O remote protocol extension}, for the specification.
22168 @item @code{g} --- read registers
22169 @anchor{read registers packet}
22170 @cindex @code{g} packet
22172 Read general registers.
22176 @item @var{XX@dots{}}
22177 Each byte of register data is described by two hex digits. The bytes
22178 with the register are transmitted in target byte order. The size of
22179 each register and their position within the @samp{g} @var{packet} are
22180 determined by the @value{GDBN} internal macros
22181 @var{DEPRECATED_REGISTER_RAW_SIZE} and @var{REGISTER_NAME} macros. The
22182 specification of several standard @code{g} packets is specified below.
22187 @item @code{G}@var{XX@dots{}} --- write regs
22188 @cindex @code{G} packet
22190 @xref{read registers packet}, for a description of the @var{XX@dots{}}
22201 @item @code{h} --- reserved
22203 Reserved for future use.
22205 @item @code{H}@var{c}@var{t@dots{}} --- set thread
22206 @cindex @code{H} packet
22208 Set thread for subsequent operations (@samp{m}, @samp{M}, @samp{g},
22209 @samp{G}, et.al.). @var{c} depends on the operation to be performed: it
22210 should be @samp{c} for step and continue operations, @samp{g} for other
22211 operations. The thread designator @var{t@dots{}} may be -1, meaning all
22212 the threads, a thread number, or zero which means pick any thread.
22223 @c 'H': How restrictive (or permissive) is the thread model. If a
22224 @c thread is selected and stopped, are other threads allowed
22225 @c to continue to execute? As I mentioned above, I think the
22226 @c semantics of each command when a thread is selected must be
22227 @c described. For example:
22229 @c 'g': If the stub supports threads and a specific thread is
22230 @c selected, returns the register block from that thread;
22231 @c otherwise returns current registers.
22233 @c 'G' If the stub supports threads and a specific thread is
22234 @c selected, sets the registers of the register block of
22235 @c that thread; otherwise sets current registers.
22237 @item @code{i}@var{addr}@code{,}@var{nnn} --- cycle step @strong{(draft)}
22238 @anchor{cycle step packet}
22239 @cindex @code{i} packet
22241 Step the remote target by a single clock cycle. If @code{,}@var{nnn} is
22242 present, cycle step @var{nnn} cycles. If @var{addr} is present, cycle
22243 step starting at that address.
22245 @item @code{I} --- signal then cycle step @strong{(reserved)}
22246 @cindex @code{I} packet
22248 @xref{step with signal packet}. @xref{cycle step packet}.
22250 @item @code{j} --- reserved
22252 Reserved for future use.
22254 @item @code{J} --- reserved
22256 Reserved for future use.
22258 @item @code{k} --- kill request
22259 @cindex @code{k} packet
22261 FIXME: @emph{There is no description of how to operate when a specific
22262 thread context has been selected (i.e.@: does 'k' kill only that
22265 @item @code{K} --- reserved
22267 Reserved for future use.
22269 @item @code{l} --- reserved
22271 Reserved for future use.
22273 @item @code{L} --- reserved
22275 Reserved for future use.
22277 @item @code{m}@var{addr}@code{,}@var{length} --- read memory
22278 @cindex @code{m} packet
22280 Read @var{length} bytes of memory starting at address @var{addr}.
22281 Neither @value{GDBN} nor the stub assume that sized memory transfers are
22282 assumed using word aligned accesses. FIXME: @emph{A word aligned memory
22283 transfer mechanism is needed.}
22287 @item @var{XX@dots{}}
22288 @var{XX@dots{}} is mem contents. Can be fewer bytes than requested if able
22289 to read only part of the data. Neither @value{GDBN} nor the stub assume
22290 that sized memory transfers are assumed using word aligned
22291 accesses. FIXME: @emph{A word aligned memory transfer mechanism is
22297 @item @code{M}@var{addr},@var{length}@code{:}@var{XX@dots{}} --- write mem
22298 @cindex @code{M} packet
22300 Write @var{length} bytes of memory starting at address @var{addr}.
22301 @var{XX@dots{}} is the data.
22308 for an error (this includes the case where only part of the data was
22312 @item @code{n} --- reserved
22314 Reserved for future use.
22316 @item @code{N} --- reserved
22318 Reserved for future use.
22320 @item @code{o} --- reserved
22322 Reserved for future use.
22324 @item @code{O} --- reserved
22326 @item @code{p}@var{hex number of register} --- read register packet
22327 @cindex @code{p} packet
22329 @xref{read registers packet}, for a description of how the returned
22330 register value is encoded.
22334 @item @var{XX@dots{}}
22335 the register's value
22339 Indicating an unrecognized @var{query}.
22342 @item @code{P}@var{n@dots{}}@code{=}@var{r@dots{}} --- write register
22343 @anchor{write register packet}
22344 @cindex @code{P} packet
22346 Write register @var{n@dots{}} with value @var{r@dots{}}, which contains two hex
22347 digits for each byte in the register (target byte order).
22357 @item @code{q}@var{query} --- general query
22358 @anchor{general query packet}
22359 @cindex @code{q} packet
22361 Request info about @var{query}. In general @value{GDBN} queries have a
22362 leading upper case letter. Custom vendor queries should use a company
22363 prefix (in lower case) ex: @samp{qfsf.var}. @var{query} may optionally
22364 be followed by a @samp{,} or @samp{;} separated list. Stubs must ensure
22365 that they match the full @var{query} name.
22369 @item @var{XX@dots{}}
22370 Hex encoded data from query. The reply can not be empty.
22374 Indicating an unrecognized @var{query}.
22377 @item @code{Q}@var{var}@code{=}@var{val} --- general set
22378 @cindex @code{Q} packet
22380 Set value of @var{var} to @var{val}.
22382 @xref{general query packet}, for a discussion of naming conventions.
22384 @item @code{r} --- reset @strong{(deprecated)}
22385 @cindex @code{r} packet
22387 Reset the entire system.
22389 @item @code{R}@var{XX} --- remote restart
22390 @cindex @code{R} packet
22392 Restart the program being debugged. @var{XX}, while needed, is ignored.
22393 This packet is only available in extended mode.
22397 @item @emph{no reply}
22398 The @samp{R} packet has no reply.
22401 @item @code{s}@var{addr} --- step
22402 @cindex @code{s} packet
22404 @var{addr} is address to resume. If @var{addr} is omitted, resume at
22408 @xref{Stop Reply Packets}, for the reply specifications.
22410 @item @code{S}@var{sig}@code{;}@var{addr} --- step with signal
22411 @anchor{step with signal packet}
22412 @cindex @code{S} packet
22414 Like @samp{C} but step not continue.
22417 @xref{Stop Reply Packets}, for the reply specifications.
22419 @item @code{t}@var{addr}@code{:}@var{PP}@code{,}@var{MM} --- search
22420 @cindex @code{t} packet
22422 Search backwards starting at address @var{addr} for a match with pattern
22423 @var{PP} and mask @var{MM}. @var{PP} and @var{MM} are 4 bytes.
22424 @var{addr} must be at least 3 digits.
22426 @item @code{T}@var{XX} --- thread alive
22427 @cindex @code{T} packet
22429 Find out if the thread XX is alive.
22434 thread is still alive
22439 @item @code{u} --- reserved
22441 Reserved for future use.
22443 @item @code{U} --- reserved
22445 Reserved for future use.
22447 @item @code{v} --- verbose packet prefix
22449 Packets starting with @code{v} are identified by a multi-letter name,
22450 up to the first @code{;} or @code{?} (or the end of the packet).
22452 @item @code{vCont}[;@var{action}[@code{:}@var{tid}]]... --- extended resume
22453 @cindex @code{vCont} packet
22455 Resume the inferior. Different actions may be specified for each thread.
22456 If an action is specified with no @var{tid}, then it is applied to any
22457 threads that don't have a specific action specified; if no default action is
22458 specified then other threads should remain stopped. Specifying multiple
22459 default actions is an error; specifying no actions is also an error.
22460 Thread IDs are specified in hexadecimal. Currently supported actions are:
22466 Continue with signal @var{sig}. @var{sig} should be two hex digits.
22470 Step with signal @var{sig}. @var{sig} should be two hex digits.
22473 The optional @var{addr} argument normally associated with these packets is
22474 not supported in @code{vCont}.
22477 @xref{Stop Reply Packets}, for the reply specifications.
22479 @item @code{vCont?} --- extended resume query
22480 @cindex @code{vCont?} packet
22482 Query support for the @code{vCont} packet.
22486 @item @code{vCont}[;@var{action}]...
22487 The @code{vCont} packet is supported. Each @var{action} is a supported
22488 command in the @code{vCont} packet.
22490 The @code{vCont} packet is not supported.
22493 @item @code{V} --- reserved
22495 Reserved for future use.
22497 @item @code{w} --- reserved
22499 Reserved for future use.
22501 @item @code{W} --- reserved
22503 Reserved for future use.
22505 @item @code{x} --- reserved
22507 Reserved for future use.
22509 @item @code{X}@var{addr}@code{,}@var{length}@var{:}@var{XX@dots{}} --- write mem (binary)
22510 @cindex @code{X} packet
22512 @var{addr} is address, @var{length} is number of bytes, @var{XX@dots{}}
22513 is binary data. The characters @code{$}, @code{#}, and @code{0x7d} are
22514 escaped using @code{0x7d}, and then XORed with @code{0x20}.
22515 For example, @code{0x7d} would be transmitted as @code{0x7d 0x5d}.
22525 @item @code{y} --- reserved
22527 Reserved for future use.
22529 @item @code{Y} reserved
22531 Reserved for future use.
22533 @item @code{z}@var{type}@code{,}@var{addr}@code{,}@var{length} --- remove breakpoint or watchpoint @strong{(draft)}
22534 @itemx @code{Z}@var{type}@code{,}@var{addr}@code{,}@var{length} --- insert breakpoint or watchpoint @strong{(draft)}
22535 @anchor{insert breakpoint or watchpoint packet}
22536 @cindex @code{z} packet
22537 @cindex @code{Z} packets
22539 Insert (@code{Z}) or remove (@code{z}) a @var{type} breakpoint or
22540 watchpoint starting at address @var{address} and covering the next
22541 @var{length} bytes.
22543 Each breakpoint and watchpoint packet @var{type} is documented
22546 @emph{Implementation notes: A remote target shall return an empty string
22547 for an unrecognized breakpoint or watchpoint packet @var{type}. A
22548 remote target shall support either both or neither of a given
22549 @code{Z}@var{type}@dots{} and @code{z}@var{type}@dots{} packet pair. To
22550 avoid potential problems with duplicate packets, the operations should
22551 be implemented in an idempotent way.}
22553 @item @code{z}@code{0}@code{,}@var{addr}@code{,}@var{length} --- remove memory breakpoint @strong{(draft)}
22554 @item @code{Z}@code{0}@code{,}@var{addr}@code{,}@var{length} --- insert memory breakpoint @strong{(draft)}
22555 @cindex @code{z0} packet
22556 @cindex @code{Z0} packet
22558 Insert (@code{Z0}) or remove (@code{z0}) a memory breakpoint at address
22559 @code{addr} of size @code{length}.
22561 A memory breakpoint is implemented by replacing the instruction at
22562 @var{addr} with a software breakpoint or trap instruction. The
22563 @code{length} is used by targets that indicates the size of the
22564 breakpoint (in bytes) that should be inserted (e.g., the @sc{arm} and
22565 @sc{mips} can insert either a 2 or 4 byte breakpoint).
22567 @emph{Implementation note: It is possible for a target to copy or move
22568 code that contains memory breakpoints (e.g., when implementing
22569 overlays). The behavior of this packet, in the presence of such a
22570 target, is not defined.}
22582 @item @code{z}@code{1}@code{,}@var{addr}@code{,}@var{length} --- remove hardware breakpoint @strong{(draft)}
22583 @item @code{Z}@code{1}@code{,}@var{addr}@code{,}@var{length} --- insert hardware breakpoint @strong{(draft)}
22584 @cindex @code{z1} packet
22585 @cindex @code{Z1} packet
22587 Insert (@code{Z1}) or remove (@code{z1}) a hardware breakpoint at
22588 address @code{addr} of size @code{length}.
22590 A hardware breakpoint is implemented using a mechanism that is not
22591 dependant on being able to modify the target's memory.
22593 @emph{Implementation note: A hardware breakpoint is not affected by code
22606 @item @code{z}@code{2}@code{,}@var{addr}@code{,}@var{length} --- remove write watchpoint @strong{(draft)}
22607 @item @code{Z}@code{2}@code{,}@var{addr}@code{,}@var{length} --- insert write watchpoint @strong{(draft)}
22608 @cindex @code{z2} packet
22609 @cindex @code{Z2} packet
22611 Insert (@code{Z2}) or remove (@code{z2}) a write watchpoint.
22623 @item @code{z}@code{3}@code{,}@var{addr}@code{,}@var{length} --- remove read watchpoint @strong{(draft)}
22624 @item @code{Z}@code{3}@code{,}@var{addr}@code{,}@var{length} --- insert read watchpoint @strong{(draft)}
22625 @cindex @code{z3} packet
22626 @cindex @code{Z3} packet
22628 Insert (@code{Z3}) or remove (@code{z3}) a read watchpoint.
22640 @item @code{z}@code{4}@code{,}@var{addr}@code{,}@var{length} --- remove access watchpoint @strong{(draft)}
22641 @item @code{Z}@code{4}@code{,}@var{addr}@code{,}@var{length} --- insert access watchpoint @strong{(draft)}
22642 @cindex @code{z4} packet
22643 @cindex @code{Z4} packet
22645 Insert (@code{Z4}) or remove (@code{z4}) an access watchpoint.
22659 @node Stop Reply Packets
22660 @section Stop Reply Packets
22661 @cindex stop reply packets
22663 The @samp{C}, @samp{c}, @samp{S}, @samp{s} and @samp{?} packets can
22664 receive any of the below as a reply. In the case of the @samp{C},
22665 @samp{c}, @samp{S} and @samp{s} packets, that reply is only returned
22666 when the target halts. In the below the exact meaning of @samp{signal
22667 number} is poorly defined. In general one of the UNIX signal numbering
22668 conventions is used.
22673 @var{AA} is the signal number
22675 @item @code{T}@var{AA}@var{n...}@code{:}@var{r...}@code{;}@var{n...}@code{:}@var{r...}@code{;}@var{n...}@code{:}@var{r...}@code{;}
22676 @cindex @code{T} packet reply
22678 @var{AA} = two hex digit signal number; @var{n...} = register number
22679 (hex), @var{r...} = target byte ordered register contents, size defined
22680 by @code{DEPRECATED_REGISTER_RAW_SIZE}; @var{n...} = @samp{thread},
22681 @var{r...} = thread process ID, this is a hex integer; @var{n...} =
22682 (@samp{watch} | @samp{rwatch} | @samp{awatch}, @var{r...} = data
22683 address, this is a hex integer; @var{n...} = other string not starting
22684 with valid hex digit. @value{GDBN} should ignore this @var{n...},
22685 @var{r...} pair and go on to the next. This way we can extend the
22690 The process exited, and @var{AA} is the exit status. This is only
22691 applicable to certain targets.
22695 The process terminated with signal @var{AA}.
22697 @item O@var{XX@dots{}}
22699 @var{XX@dots{}} is hex encoding of @sc{ascii} data. This can happen at
22700 any time while the program is running and the debugger should continue
22701 to wait for @samp{W}, @samp{T}, etc.
22703 @item F@var{call-id}@code{,}@var{parameter@dots{}}
22705 @var{call-id} is the identifier which says which host system call should
22706 be called. This is just the name of the function. Translation into the
22707 correct system call is only applicable as it's defined in @value{GDBN}.
22708 @xref{File-I/O remote protocol extension}, for a list of implemented
22711 @var{parameter@dots{}} is a list of parameters as defined for this very
22714 The target replies with this packet when it expects @value{GDBN} to call
22715 a host system call on behalf of the target. @value{GDBN} replies with
22716 an appropriate @code{F} packet and keeps up waiting for the next reply
22717 packet from the target. The latest @samp{C}, @samp{c}, @samp{S} or
22718 @samp{s} action is expected to be continued.
22719 @xref{File-I/O remote protocol extension}, for more details.
22723 @node General Query Packets
22724 @section General Query Packets
22725 @cindex remote query requests
22727 The following set and query packets have already been defined.
22731 @item @code{q}@code{C} --- current thread
22732 @cindex current thread, remote request
22733 @cindex @code{qC} packet
22734 Return the current thread id.
22738 @item @code{QC}@var{pid}
22739 Where @var{pid} is an unsigned hexidecimal process id.
22741 Any other reply implies the old pid.
22744 @item @code{q}@code{fThreadInfo} -- all thread ids
22745 @cindex list active threads, remote request
22746 @cindex @code{qfThreadInfo} packet
22747 @code{q}@code{sThreadInfo}
22749 Obtain a list of active thread ids from the target (OS). Since there
22750 may be too many active threads to fit into one reply packet, this query
22751 works iteratively: it may require more than one query/reply sequence to
22752 obtain the entire list of threads. The first query of the sequence will
22753 be the @code{qf}@code{ThreadInfo} query; subsequent queries in the
22754 sequence will be the @code{qs}@code{ThreadInfo} query.
22756 NOTE: replaces the @code{qL} query (see below).
22760 @item @code{m}@var{id}
22762 @item @code{m}@var{id},@var{id}@dots{}
22763 a comma-separated list of thread ids
22765 (lower case 'el') denotes end of list.
22768 In response to each query, the target will reply with a list of one or
22769 more thread ids, in big-endian unsigned hex, separated by commas.
22770 @value{GDBN} will respond to each reply with a request for more thread
22771 ids (using the @code{qs} form of the query), until the target responds
22772 with @code{l} (lower-case el, for @code{'last'}).
22774 @item @code{q}@code{ThreadExtraInfo}@code{,}@var{id} --- extra thread info
22775 @cindex thread attributes info, remote request
22776 @cindex @code{qThreadExtraInfo} packet
22777 Where @var{id} is a thread-id in big-endian hex. Obtain a printable
22778 string description of a thread's attributes from the target OS. This
22779 string may contain anything that the target OS thinks is interesting for
22780 @value{GDBN} to tell the user about the thread. The string is displayed
22781 in @value{GDBN}'s @samp{info threads} display. Some examples of
22782 possible thread extra info strings are ``Runnable'', or ``Blocked on
22787 @item @var{XX@dots{}}
22788 Where @var{XX@dots{}} is a hex encoding of @sc{ascii} data, comprising
22789 the printable string containing the extra information about the thread's
22793 @item @code{q}@code{L}@var{startflag}@var{threadcount}@var{nextthread} --- query @var{LIST} or @var{threadLIST} @strong{(deprecated)}
22795 Obtain thread information from RTOS. Where: @var{startflag} (one hex
22796 digit) is one to indicate the first query and zero to indicate a
22797 subsequent query; @var{threadcount} (two hex digits) is the maximum
22798 number of threads the response packet can contain; and @var{nextthread}
22799 (eight hex digits), for subsequent queries (@var{startflag} is zero), is
22800 returned in the response as @var{argthread}.
22802 NOTE: this query is replaced by the @code{q}@code{fThreadInfo} query
22807 @item @code{q}@code{M}@var{count}@var{done}@var{argthread}@var{thread@dots{}}
22808 Where: @var{count} (two hex digits) is the number of threads being
22809 returned; @var{done} (one hex digit) is zero to indicate more threads
22810 and one indicates no further threads; @var{argthreadid} (eight hex
22811 digits) is @var{nextthread} from the request packet; @var{thread@dots{}}
22812 is a sequence of thread IDs from the target. @var{threadid} (eight hex
22813 digits). See @code{remote.c:parse_threadlist_response()}.
22816 @item @code{q}@code{CRC:}@var{addr}@code{,}@var{length} --- compute CRC of memory block
22817 @cindex CRC of memory block, remote request
22818 @cindex @code{qCRC} packet
22821 @item @code{E}@var{NN}
22822 An error (such as memory fault)
22823 @item @code{C}@var{CRC32}
22824 A 32 bit cyclic redundancy check of the specified memory region.
22827 @item @code{q}@code{Offsets} --- query sect offs
22828 @cindex section offsets, remote request
22829 @cindex @code{qOffsets} packet
22830 Get section offsets that the target used when re-locating the downloaded
22831 image. @emph{Note: while a @code{Bss} offset is included in the
22832 response, @value{GDBN} ignores this and instead applies the @code{Data}
22833 offset to the @code{Bss} section.}
22837 @item @code{Text=}@var{xxx}@code{;Data=}@var{yyy}@code{;Bss=}@var{zzz}
22840 @item @code{q}@code{P}@var{mode}@var{threadid} --- thread info request
22841 @cindex thread information, remote request
22842 @cindex @code{qP} packet
22843 Returns information on @var{threadid}. Where: @var{mode} is a hex
22844 encoded 32 bit mode; @var{threadid} is a hex encoded 64 bit thread ID.
22851 See @code{remote.c:remote_unpack_thread_info_response()}.
22853 @item @code{q}@code{Rcmd,}@var{command} --- remote command
22854 @cindex execute remote command, remote request
22855 @cindex @code{qRcmd} packet
22856 @var{command} (hex encoded) is passed to the local interpreter for
22857 execution. Invalid commands should be reported using the output string.
22858 Before the final result packet, the target may also respond with a
22859 number of intermediate @code{O}@var{output} console output packets.
22860 @emph{Implementors should note that providing access to a stubs's
22861 interpreter may have security implications}.
22866 A command response with no output.
22868 A command response with the hex encoded output string @var{OUTPUT}.
22869 @item @code{E}@var{NN}
22870 Indicate a badly formed request.
22872 When @samp{q}@samp{Rcmd} is not recognized.
22875 @item @code{qSymbol::} --- symbol lookup
22876 @cindex symbol lookup, remote request
22877 @cindex @code{qSymbol} packet
22878 Notify the target that @value{GDBN} is prepared to serve symbol lookup
22879 requests. Accept requests from the target for the values of symbols.
22884 The target does not need to look up any (more) symbols.
22885 @item @code{qSymbol:}@var{sym_name}
22886 The target requests the value of symbol @var{sym_name} (hex encoded).
22887 @value{GDBN} may provide the value by using the
22888 @code{qSymbol:}@var{sym_value}:@var{sym_name} message, described below.
22891 @item @code{qSymbol:}@var{sym_value}:@var{sym_name} --- symbol value
22893 Set the value of @var{sym_name} to @var{sym_value}.
22895 @var{sym_name} (hex encoded) is the name of a symbol whose value the
22896 target has previously requested.
22898 @var{sym_value} (hex) is the value for symbol @var{sym_name}. If
22899 @value{GDBN} cannot supply a value for @var{sym_name}, then this field
22905 The target does not need to look up any (more) symbols.
22906 @item @code{qSymbol:}@var{sym_name}
22907 The target requests the value of a new symbol @var{sym_name} (hex
22908 encoded). @value{GDBN} will continue to supply the values of symbols
22909 (if available), until the target ceases to request them.
22912 @item @code{qPart}:@var{object}:@code{read}:@var{annex}:@var{offset},@var{length} --- read special data
22913 @cindex read special object, remote request
22914 @cindex @code{qPart} packet
22915 Read uninterpreted bytes from the target's special data area
22916 identified by the keyword @code{object}.
22917 Request @var{length} bytes starting at @var{offset} bytes into the data.
22918 The content and encoding of @var{annex} is specific to the object;
22919 it can supply additional details about what data to access.
22921 Here are the specific requests of this form defined so far.
22922 All @samp{@code{qPart}:@var{object}:@code{read}:@dots{}}
22923 requests use the same reply formats, listed below.
22926 @item @code{qPart}:@code{auxv}:@code{read}::@var{offset},@var{length}
22927 Access the target's @dfn{auxiliary vector}. @xref{OS Information,
22928 auxiliary vector}, and see @ref{Remote configuration,
22929 read-aux-vector-packet}. Note @var{annex} must be empty.
22935 The @var{offset} in the request is at the end of the data.
22936 There is no more data to be read.
22938 @item @var{XX@dots{}}
22939 Hex encoded data bytes read.
22940 This may be fewer bytes than the @var{length} in the request.
22943 The request was malformed, or @var{annex} was invalid.
22945 @item @code{E}@var{nn}
22946 The offset was invalid, or there was an error encountered reading the data.
22947 @var{nn} is a hex-encoded @code{errno} value.
22949 @item @code{""} (empty)
22950 An empty reply indicates the @var{object} or @var{annex} string was not
22951 recognized by the stub.
22954 @item @code{qPart}:@var{object}:@code{write}:@var{annex}:@var{offset}:@var{data@dots{}}
22955 @cindex write data into object, remote request
22956 Write uninterpreted bytes into the target's special data area
22957 identified by the keyword @code{object},
22958 starting at @var{offset} bytes into the data.
22959 @var{data@dots{}} is the hex-encoded data to be written.
22960 The content and encoding of @var{annex} is specific to the object;
22961 it can supply additional details about what data to access.
22963 No requests of this form are presently in use. This specification
22964 serves as a placeholder to document the common format that new
22965 specific request specifications ought to use.
22970 @var{nn} (hex encoded) is the number of bytes written.
22971 This may be fewer bytes than supplied in the request.
22974 The request was malformed, or @var{annex} was invalid.
22976 @item @code{E}@var{nn}
22977 The offset was invalid, or there was an error encountered writing the data.
22978 @var{nn} is a hex-encoded @code{errno} value.
22980 @item @code{""} (empty)
22981 An empty reply indicates the @var{object} or @var{annex} string was not
22982 recognized by the stub, or that the object does not support writing.
22985 @item @code{qPart}:@var{object}:@var{operation}:@dots{}
22986 Requests of this form may be added in the future. When a stub does
22987 not recognize the @var{object} keyword, or its support for
22988 @var{object} does not recognize the @var{operation} keyword,
22989 the stub must respond with an empty packet.
22991 @item @code{qGetTLSAddr}:@var{thread-id},@var{offset},@var{lm} --- get thread local storage address
22992 @cindex get thread-local storage address, remote request
22993 @cindex @code{qGetTLSAddr} packet
22994 Fetch the address associated with thread local storage specified
22995 by @var{thread-id}, @var{offset}, and @var{lm}.
22997 @var{thread-id} is the (big endian, hex encoded) thread id associated with the
22998 thread for which to fetch the TLS address.
23000 @var{offset} is the (big endian, hex encoded) offset associated with the
23001 thread local variable. (This offset is obtained from the debug
23002 information associated with the variable.)
23004 @var{lm} is the (big endian, hex encoded) OS/ABI specific encoding of the
23005 the load module associated with the thread local storage. For example,
23006 a @sc{gnu}/Linux system will pass the link map address of the shared
23007 object associated with the thread local storage under consideration.
23008 Other operating environments may choose to represent the load module
23009 differently, so the precise meaning of this parameter will vary.
23013 @item @var{XX@dots{}}
23014 Hex encoded (big endian) bytes representing the address of the thread
23015 local storage requested.
23017 @item @code{E}@var{nn} (where @var{nn} are hex digits)
23020 @item @code{""} (empty)
23021 An empty reply indicates that @code{qGetTLSAddr} is not supported by the stub.
23024 Use of this request packet is controlled by the @code{set remote
23025 get-thread-local-storage-address} command (@pxref{Remote
23026 configuration, set remote get-thread-local-storage-address}).
23030 @node Register Packet Format
23031 @section Register Packet Format
23033 The following @samp{g}/@samp{G} packets have previously been defined.
23034 In the below, some thirty-two bit registers are transferred as
23035 sixty-four bits. Those registers should be zero/sign extended (which?)
23036 to fill the space allocated. Register bytes are transfered in target
23037 byte order. The two nibbles within a register byte are transfered
23038 most-significant - least-significant.
23044 All registers are transfered as thirty-two bit quantities in the order:
23045 32 general-purpose; sr; lo; hi; bad; cause; pc; 32 floating-point
23046 registers; fsr; fir; fp.
23050 All registers are transfered as sixty-four bit quantities (including
23051 thirty-two bit registers such as @code{sr}). The ordering is the same
23059 Example sequence of a target being re-started. Notice how the restart
23060 does not get any direct output:
23065 @emph{target restarts}
23068 <- @code{T001:1234123412341234}
23072 Example sequence of a target being stepped by a single instruction:
23075 -> @code{G1445@dots{}}
23080 <- @code{T001:1234123412341234}
23084 <- @code{1455@dots{}}
23088 @node File-I/O remote protocol extension
23089 @section File-I/O remote protocol extension
23090 @cindex File-I/O remote protocol extension
23093 * File-I/O Overview::
23094 * Protocol basics::
23095 * The F request packet::
23096 * The F reply packet::
23097 * Memory transfer::
23098 * The Ctrl-C message::
23100 * The isatty call::
23101 * The system call::
23102 * List of supported calls::
23103 * Protocol specific representation of datatypes::
23105 * File-I/O Examples::
23108 @node File-I/O Overview
23109 @subsection File-I/O Overview
23110 @cindex file-i/o overview
23112 The @dfn{File I/O remote protocol extension} (short: File-I/O) allows the
23113 target to use the host's file system and console I/O when calling various
23114 system calls. System calls on the target system are translated into a
23115 remote protocol packet to the host system which then performs the needed
23116 actions and returns with an adequate response packet to the target system.
23117 This simulates file system operations even on targets that lack file systems.
23119 The protocol is defined host- and target-system independent. It uses
23120 its own independent representation of datatypes and values. Both,
23121 @value{GDBN} and the target's @value{GDBN} stub are responsible for
23122 translating the system dependent values into the unified protocol values
23123 when data is transmitted.
23125 The communication is synchronous. A system call is possible only
23126 when GDB is waiting for the @samp{C}, @samp{c}, @samp{S} or @samp{s}
23127 packets. While @value{GDBN} handles the request for a system call,
23128 the target is stopped to allow deterministic access to the target's
23129 memory. Therefore File-I/O is not interuptible by target signals. It
23130 is possible to interrupt File-I/O by a user interrupt (Ctrl-C), though.
23132 The target's request to perform a host system call does not finish
23133 the latest @samp{C}, @samp{c}, @samp{S} or @samp{s} action. That means,
23134 after finishing the system call, the target returns to continuing the
23135 previous activity (continue, step). No additional continue or step
23136 request from @value{GDBN} is required.
23139 (@value{GDBP}) continue
23140 <- target requests 'system call X'
23141 target is stopped, @value{GDBN} executes system call
23142 -> GDB returns result
23143 ... target continues, GDB returns to wait for the target
23144 <- target hits breakpoint and sends a Txx packet
23147 The protocol is only used for files on the host file system and
23148 for I/O on the console. Character or block special devices, pipes,
23149 named pipes or sockets or any other communication method on the host
23150 system are not supported by this protocol.
23152 @node Protocol basics
23153 @subsection Protocol basics
23154 @cindex protocol basics, file-i/o
23156 The File-I/O protocol uses the @code{F} packet, as request as well
23157 as as reply packet. Since a File-I/O system call can only occur when
23158 @value{GDBN} is waiting for the continuing or stepping target, the
23159 File-I/O request is a reply that @value{GDBN} has to expect as a result
23160 of a former @samp{C}, @samp{c}, @samp{S} or @samp{s} packet.
23161 This @code{F} packet contains all information needed to allow @value{GDBN}
23162 to call the appropriate host system call:
23166 A unique identifier for the requested system call.
23169 All parameters to the system call. Pointers are given as addresses
23170 in the target memory address space. Pointers to strings are given as
23171 pointer/length pair. Numerical values are given as they are.
23172 Numerical control values are given in a protocol specific representation.
23176 At that point @value{GDBN} has to perform the following actions.
23180 If parameter pointer values are given, which point to data needed as input
23181 to a system call, @value{GDBN} requests this data from the target with a
23182 standard @code{m} packet request. This additional communication has to be
23183 expected by the target implementation and is handled as any other @code{m}
23187 @value{GDBN} translates all value from protocol representation to host
23188 representation as needed. Datatypes are coerced into the host types.
23191 @value{GDBN} calls the system call
23194 It then coerces datatypes back to protocol representation.
23197 If pointer parameters in the request packet point to buffer space in which
23198 a system call is expected to copy data to, the data is transmitted to the
23199 target using a @code{M} or @code{X} packet. This packet has to be expected
23200 by the target implementation and is handled as any other @code{M} or @code{X}
23205 Eventually @value{GDBN} replies with another @code{F} packet which contains all
23206 necessary information for the target to continue. This at least contains
23213 @code{errno}, if has been changed by the system call.
23220 After having done the needed type and value coercion, the target continues
23221 the latest continue or step action.
23223 @node The F request packet
23224 @subsection The @code{F} request packet
23225 @cindex file-i/o request packet
23226 @cindex @code{F} request packet
23228 The @code{F} request packet has the following format:
23233 @code{F}@var{call-id}@code{,}@var{parameter@dots{}}
23236 @var{call-id} is the identifier to indicate the host system call to be called.
23237 This is just the name of the function.
23239 @var{parameter@dots{}} are the parameters to the system call.
23243 Parameters are hexadecimal integer values, either the real values in case
23244 of scalar datatypes, as pointers to target buffer space in case of compound
23245 datatypes and unspecified memory areas or as pointer/length pairs in case
23246 of string parameters. These are appended to the call-id, each separated
23247 from its predecessor by a comma. All values are transmitted in ASCII
23248 string representation, pointer/length pairs separated by a slash.
23250 @node The F reply packet
23251 @subsection The @code{F} reply packet
23252 @cindex file-i/o reply packet
23253 @cindex @code{F} reply packet
23255 The @code{F} reply packet has the following format:
23260 @code{F}@var{retcode}@code{,}@var{errno}@code{,}@var{Ctrl-C flag}@code{;}@var{call specific attachment}
23263 @var{retcode} is the return code of the system call as hexadecimal value.
23265 @var{errno} is the errno set by the call, in protocol specific representation.
23266 This parameter can be omitted if the call was successful.
23268 @var{Ctrl-C flag} is only send if the user requested a break. In this
23269 case, @var{errno} must be send as well, even if the call was successful.
23270 The @var{Ctrl-C flag} itself consists of the character 'C':
23277 or, if the call was interupted before the host call has been performed:
23284 assuming 4 is the protocol specific representation of @code{EINTR}.
23288 @node Memory transfer
23289 @subsection Memory transfer
23290 @cindex memory transfer, in file-i/o protocol
23292 Structured data which is transferred using a memory read or write as e.g.@:
23293 a @code{struct stat} is expected to be in a protocol specific format with
23294 all scalar multibyte datatypes being big endian. This should be done by
23295 the target before the @code{F} packet is sent resp.@: by @value{GDBN} before
23296 it transfers memory to the target. Transferred pointers to structured
23297 data should point to the already coerced data at any time.
23299 @node The Ctrl-C message
23300 @subsection The Ctrl-C message
23301 @cindex ctrl-c message, in file-i/o protocol
23303 A special case is, if the @var{Ctrl-C flag} is set in the @value{GDBN}
23304 reply packet. In this case the target should behave, as if it had
23305 gotten a break message. The meaning for the target is ``system call
23306 interupted by @code{SIGINT}''. Consequentially, the target should actually stop
23307 (as with a break message) and return to @value{GDBN} with a @code{T02}
23308 packet. In this case, it's important for the target to know, in which
23309 state the system call was interrupted. Since this action is by design
23310 not an atomic operation, we have to differ between two cases:
23314 The system call hasn't been performed on the host yet.
23317 The system call on the host has been finished.
23321 These two states can be distinguished by the target by the value of the
23322 returned @code{errno}. If it's the protocol representation of @code{EINTR}, the system
23323 call hasn't been performed. This is equivalent to the @code{EINTR} handling
23324 on POSIX systems. In any other case, the target may presume that the
23325 system call has been finished --- successful or not --- and should behave
23326 as if the break message arrived right after the system call.
23328 @value{GDBN} must behave reliable. If the system call has not been called
23329 yet, @value{GDBN} may send the @code{F} reply immediately, setting @code{EINTR} as
23330 @code{errno} in the packet. If the system call on the host has been finished
23331 before the user requests a break, the full action must be finshed by
23332 @value{GDBN}. This requires sending @code{M} or @code{X} packets as they fit.
23333 The @code{F} packet may only be send when either nothing has happened
23334 or the full action has been completed.
23337 @subsection Console I/O
23338 @cindex console i/o as part of file-i/o
23340 By default and if not explicitely closed by the target system, the file
23341 descriptors 0, 1 and 2 are connected to the @value{GDBN} console. Output
23342 on the @value{GDBN} console is handled as any other file output operation
23343 (@code{write(1, @dots{})} or @code{write(2, @dots{})}). Console input is handled
23344 by @value{GDBN} so that after the target read request from file descriptor
23345 0 all following typing is buffered until either one of the following
23350 The user presses @kbd{Ctrl-C}. The behaviour is as explained above, the
23352 system call is treated as finished.
23355 The user presses @kbd{Enter}. This is treated as end of input with a trailing
23359 The user presses @kbd{Ctrl-D}. This is treated as end of input. No trailing
23360 character, especially no Ctrl-D is appended to the input.
23364 If the user has typed more characters as fit in the buffer given to
23365 the read call, the trailing characters are buffered in @value{GDBN} until
23366 either another @code{read(0, @dots{})} is requested by the target or debugging
23367 is stopped on users request.
23369 @node The isatty call
23370 @subsection The @samp{isatty} function call
23371 @cindex isatty call, file-i/o protocol
23373 A special case in this protocol is the library call @code{isatty} which
23374 is implemented as its own call inside of this protocol. It returns
23375 1 to the target if the file descriptor given as parameter is attached
23376 to the @value{GDBN} console, 0 otherwise. Implementing through system calls
23377 would require implementing @code{ioctl} and would be more complex than
23380 @node The system call
23381 @subsection The @samp{system} function call
23382 @cindex system call, file-i/o protocol
23384 The other special case in this protocol is the @code{system} call which
23385 is implemented as its own call, too. @value{GDBN} is taking over the full
23386 task of calling the necessary host calls to perform the @code{system}
23387 call. The return value of @code{system} is simplified before it's returned
23388 to the target. Basically, the only signal transmitted back is @code{EINTR}
23389 in case the user pressed @kbd{Ctrl-C}. Otherwise the return value consists
23390 entirely of the exit status of the called command.
23392 Due to security concerns, the @code{system} call is by default refused
23393 by @value{GDBN}. The user has to allow this call explicitly with the
23394 @kbd{set remote system-call-allowed 1} command.
23397 @item set remote system-call-allowed
23398 @kindex set remote system-call-allowed
23399 Control whether to allow the @code{system} calls in the File I/O
23400 protocol for the remote target. The default is zero (disabled).
23402 @item show remote system-call-allowed
23403 @kindex show remote system-call-allowed
23404 Show the current setting of system calls for the remote File I/O
23408 @node List of supported calls
23409 @subsection List of supported calls
23410 @cindex list of supported file-i/o calls
23427 @unnumberedsubsubsec open
23428 @cindex open, file-i/o system call
23432 int open(const char *pathname, int flags);
23433 int open(const char *pathname, int flags, mode_t mode);
23436 Fopen,pathptr/len,flags,mode
23440 @code{flags} is the bitwise or of the following values:
23444 If the file does not exist it will be created. The host
23445 rules apply as far as file ownership and time stamps
23449 When used with O_CREAT, if the file already exists it is
23450 an error and open() fails.
23453 If the file already exists and the open mode allows
23454 writing (O_RDWR or O_WRONLY is given) it will be
23455 truncated to length 0.
23458 The file is opened in append mode.
23461 The file is opened for reading only.
23464 The file is opened for writing only.
23467 The file is opened for reading and writing.
23470 Each other bit is silently ignored.
23475 @code{mode} is the bitwise or of the following values:
23479 User has read permission.
23482 User has write permission.
23485 Group has read permission.
23488 Group has write permission.
23491 Others have read permission.
23494 Others have write permission.
23497 Each other bit is silently ignored.
23502 @exdent Return value:
23503 open returns the new file descriptor or -1 if an error
23511 pathname already exists and O_CREAT and O_EXCL were used.
23514 pathname refers to a directory.
23517 The requested access is not allowed.
23520 pathname was too long.
23523 A directory component in pathname does not exist.
23526 pathname refers to a device, pipe, named pipe or socket.
23529 pathname refers to a file on a read-only filesystem and
23530 write access was requested.
23533 pathname is an invalid pointer value.
23536 No space on device to create the file.
23539 The process already has the maximum number of files open.
23542 The limit on the total number of files open on the system
23546 The call was interrupted by the user.
23550 @unnumberedsubsubsec close
23551 @cindex close, file-i/o system call
23560 @exdent Return value:
23561 close returns zero on success, or -1 if an error occurred.
23568 fd isn't a valid open file descriptor.
23571 The call was interrupted by the user.
23575 @unnumberedsubsubsec read
23576 @cindex read, file-i/o system call
23580 int read(int fd, void *buf, unsigned int count);
23583 Fread,fd,bufptr,count
23585 @exdent Return value:
23586 On success, the number of bytes read is returned.
23587 Zero indicates end of file. If count is zero, read
23588 returns zero as well. On error, -1 is returned.
23595 fd is not a valid file descriptor or is not open for
23599 buf is an invalid pointer value.
23602 The call was interrupted by the user.
23606 @unnumberedsubsubsec write
23607 @cindex write, file-i/o system call
23611 int write(int fd, const void *buf, unsigned int count);
23614 Fwrite,fd,bufptr,count
23616 @exdent Return value:
23617 On success, the number of bytes written are returned.
23618 Zero indicates nothing was written. On error, -1
23626 fd is not a valid file descriptor or is not open for
23630 buf is an invalid pointer value.
23633 An attempt was made to write a file that exceeds the
23634 host specific maximum file size allowed.
23637 No space on device to write the data.
23640 The call was interrupted by the user.
23644 @unnumberedsubsubsec lseek
23645 @cindex lseek, file-i/o system call
23649 long lseek (int fd, long offset, int flag);
23652 Flseek,fd,offset,flag
23655 @code{flag} is one of:
23659 The offset is set to offset bytes.
23662 The offset is set to its current location plus offset
23666 The offset is set to the size of the file plus offset
23671 @exdent Return value:
23672 On success, the resulting unsigned offset in bytes from
23673 the beginning of the file is returned. Otherwise, a
23674 value of -1 is returned.
23681 fd is not a valid open file descriptor.
23684 fd is associated with the @value{GDBN} console.
23687 flag is not a proper value.
23690 The call was interrupted by the user.
23694 @unnumberedsubsubsec rename
23695 @cindex rename, file-i/o system call
23699 int rename(const char *oldpath, const char *newpath);
23702 Frename,oldpathptr/len,newpathptr/len
23704 @exdent Return value:
23705 On success, zero is returned. On error, -1 is returned.
23712 newpath is an existing directory, but oldpath is not a
23716 newpath is a non-empty directory.
23719 oldpath or newpath is a directory that is in use by some
23723 An attempt was made to make a directory a subdirectory
23727 A component used as a directory in oldpath or new
23728 path is not a directory. Or oldpath is a directory
23729 and newpath exists but is not a directory.
23732 oldpathptr or newpathptr are invalid pointer values.
23735 No access to the file or the path of the file.
23739 oldpath or newpath was too long.
23742 A directory component in oldpath or newpath does not exist.
23745 The file is on a read-only filesystem.
23748 The device containing the file has no room for the new
23752 The call was interrupted by the user.
23756 @unnumberedsubsubsec unlink
23757 @cindex unlink, file-i/o system call
23761 int unlink(const char *pathname);
23764 Funlink,pathnameptr/len
23766 @exdent Return value:
23767 On success, zero is returned. On error, -1 is returned.
23774 No access to the file or the path of the file.
23777 The system does not allow unlinking of directories.
23780 The file pathname cannot be unlinked because it's
23781 being used by another process.
23784 pathnameptr is an invalid pointer value.
23787 pathname was too long.
23790 A directory component in pathname does not exist.
23793 A component of the path is not a directory.
23796 The file is on a read-only filesystem.
23799 The call was interrupted by the user.
23803 @unnumberedsubsubsec stat/fstat
23804 @cindex fstat, file-i/o system call
23805 @cindex stat, file-i/o system call
23809 int stat(const char *pathname, struct stat *buf);
23810 int fstat(int fd, struct stat *buf);
23813 Fstat,pathnameptr/len,bufptr
23816 @exdent Return value:
23817 On success, zero is returned. On error, -1 is returned.
23824 fd is not a valid open file.
23827 A directory component in pathname does not exist or the
23828 path is an empty string.
23831 A component of the path is not a directory.
23834 pathnameptr is an invalid pointer value.
23837 No access to the file or the path of the file.
23840 pathname was too long.
23843 The call was interrupted by the user.
23847 @unnumberedsubsubsec gettimeofday
23848 @cindex gettimeofday, file-i/o system call
23852 int gettimeofday(struct timeval *tv, void *tz);
23855 Fgettimeofday,tvptr,tzptr
23857 @exdent Return value:
23858 On success, 0 is returned, -1 otherwise.
23865 tz is a non-NULL pointer.
23868 tvptr and/or tzptr is an invalid pointer value.
23872 @unnumberedsubsubsec isatty
23873 @cindex isatty, file-i/o system call
23877 int isatty(int fd);
23882 @exdent Return value:
23883 Returns 1 if fd refers to the @value{GDBN} console, 0 otherwise.
23890 The call was interrupted by the user.
23894 @unnumberedsubsubsec system
23895 @cindex system, file-i/o system call
23899 int system(const char *command);
23902 Fsystem,commandptr/len
23904 @exdent Return value:
23905 The value returned is -1 on error and the return status
23906 of the command otherwise. Only the exit status of the
23907 command is returned, which is extracted from the hosts
23908 system return value by calling WEXITSTATUS(retval).
23909 In case /bin/sh could not be executed, 127 is returned.
23916 The call was interrupted by the user.
23919 @node Protocol specific representation of datatypes
23920 @subsection Protocol specific representation of datatypes
23921 @cindex protocol specific representation of datatypes, in file-i/o protocol
23924 * Integral datatypes::
23930 @node Integral datatypes
23931 @unnumberedsubsubsec Integral datatypes
23932 @cindex integral datatypes, in file-i/o protocol
23934 The integral datatypes used in the system calls are
23937 int@r{,} unsigned int@r{,} long@r{,} unsigned long@r{,} mode_t @r{and} time_t
23940 @code{Int}, @code{unsigned int}, @code{mode_t} and @code{time_t} are
23941 implemented as 32 bit values in this protocol.
23943 @code{Long} and @code{unsigned long} are implemented as 64 bit types.
23945 @xref{Limits}, for corresponding MIN and MAX values (similar to those
23946 in @file{limits.h}) to allow range checking on host and target.
23948 @code{time_t} datatypes are defined as seconds since the Epoch.
23950 All integral datatypes transferred as part of a memory read or write of a
23951 structured datatype e.g.@: a @code{struct stat} have to be given in big endian
23954 @node Pointer values
23955 @unnumberedsubsubsec Pointer values
23956 @cindex pointer values, in file-i/o protocol
23958 Pointers to target data are transmitted as they are. An exception
23959 is made for pointers to buffers for which the length isn't
23960 transmitted as part of the function call, namely strings. Strings
23961 are transmitted as a pointer/length pair, both as hex values, e.g.@:
23968 which is a pointer to data of length 18 bytes at position 0x1aaf.
23969 The length is defined as the full string length in bytes, including
23970 the trailing null byte. Example:
23973 ``hello, world'' at address 0x123456
23984 @unnumberedsubsubsec struct stat
23985 @cindex struct stat, in file-i/o protocol
23987 The buffer of type struct stat used by the target and @value{GDBN} is defined
23992 unsigned int st_dev; /* device */
23993 unsigned int st_ino; /* inode */
23994 mode_t st_mode; /* protection */
23995 unsigned int st_nlink; /* number of hard links */
23996 unsigned int st_uid; /* user ID of owner */
23997 unsigned int st_gid; /* group ID of owner */
23998 unsigned int st_rdev; /* device type (if inode device) */
23999 unsigned long st_size; /* total size, in bytes */
24000 unsigned long st_blksize; /* blocksize for filesystem I/O */
24001 unsigned long st_blocks; /* number of blocks allocated */
24002 time_t st_atime; /* time of last access */
24003 time_t st_mtime; /* time of last modification */
24004 time_t st_ctime; /* time of last change */
24008 The integral datatypes are conforming to the definitions given in the
24009 approriate section (see @ref{Integral datatypes}, for details) so this
24010 structure is of size 64 bytes.
24012 The values of several fields have a restricted meaning and/or
24019 st_ino: No valid meaning for the target. Transmitted unchanged.
24021 st_mode: Valid mode bits are described in Appendix C. Any other
24022 bits have currently no meaning for the target.
24024 st_uid: No valid meaning for the target. Transmitted unchanged.
24026 st_gid: No valid meaning for the target. Transmitted unchanged.
24028 st_rdev: No valid meaning for the target. Transmitted unchanged.
24030 st_atime, st_mtime, st_ctime:
24031 These values have a host and file system dependent
24032 accuracy. Especially on Windows hosts the file systems
24033 don't support exact timing values.
24036 The target gets a struct stat of the above representation and is
24037 responsible to coerce it to the target representation before
24040 Note that due to size differences between the host and target
24041 representation of stat members, these members could eventually
24042 get truncated on the target.
24044 @node struct timeval
24045 @unnumberedsubsubsec struct timeval
24046 @cindex struct timeval, in file-i/o protocol
24048 The buffer of type struct timeval used by the target and @value{GDBN}
24049 is defined as follows:
24053 time_t tv_sec; /* second */
24054 long tv_usec; /* microsecond */
24058 The integral datatypes are conforming to the definitions given in the
24059 approriate section (see @ref{Integral datatypes}, for details) so this
24060 structure is of size 8 bytes.
24063 @subsection Constants
24064 @cindex constants, in file-i/o protocol
24066 The following values are used for the constants inside of the
24067 protocol. @value{GDBN} and target are resposible to translate these
24068 values before and after the call as needed.
24079 @unnumberedsubsubsec Open flags
24080 @cindex open flags, in file-i/o protocol
24082 All values are given in hexadecimal representation.
24094 @node mode_t values
24095 @unnumberedsubsubsec mode_t values
24096 @cindex mode_t values, in file-i/o protocol
24098 All values are given in octal representation.
24115 @unnumberedsubsubsec Errno values
24116 @cindex errno values, in file-i/o protocol
24118 All values are given in decimal representation.
24143 EUNKNOWN is used as a fallback error value if a host system returns
24144 any error value not in the list of supported error numbers.
24147 @unnumberedsubsubsec Lseek flags
24148 @cindex lseek flags, in file-i/o protocol
24157 @unnumberedsubsubsec Limits
24158 @cindex limits, in file-i/o protocol
24160 All values are given in decimal representation.
24163 INT_MIN -2147483648
24165 UINT_MAX 4294967295
24166 LONG_MIN -9223372036854775808
24167 LONG_MAX 9223372036854775807
24168 ULONG_MAX 18446744073709551615
24171 @node File-I/O Examples
24172 @subsection File-I/O Examples
24173 @cindex file-i/o examples
24175 Example sequence of a write call, file descriptor 3, buffer is at target
24176 address 0x1234, 6 bytes should be written:
24179 <- @code{Fwrite,3,1234,6}
24180 @emph{request memory read from target}
24183 @emph{return "6 bytes written"}
24187 Example sequence of a read call, file descriptor 3, buffer is at target
24188 address 0x1234, 6 bytes should be read:
24191 <- @code{Fread,3,1234,6}
24192 @emph{request memory write to target}
24193 -> @code{X1234,6:XXXXXX}
24194 @emph{return "6 bytes read"}
24198 Example sequence of a read call, call fails on the host due to invalid
24199 file descriptor (EBADF):
24202 <- @code{Fread,3,1234,6}
24206 Example sequence of a read call, user presses Ctrl-C before syscall on
24210 <- @code{Fread,3,1234,6}
24215 Example sequence of a read call, user presses Ctrl-C after syscall on
24219 <- @code{Fread,3,1234,6}
24220 -> @code{X1234,6:XXXXXX}
24224 @include agentexpr.texi
24238 % I think something like @colophon should be in texinfo. In the
24240 \long\def\colophon{\hbox to0pt{}\vfill
24241 \centerline{The body of this manual is set in}
24242 \centerline{\fontname\tenrm,}
24243 \centerline{with headings in {\bf\fontname\tenbf}}
24244 \centerline{and examples in {\tt\fontname\tentt}.}
24245 \centerline{{\it\fontname\tenit\/},}
24246 \centerline{{\bf\fontname\tenbf}, and}
24247 \centerline{{\sl\fontname\tensl\/}}
24248 \centerline{are used for emphasis.}\vfill}
24250 % Blame: doc@cygnus.com, 1991.