Commit | Line | Data |
---|---|---|
c906108c SS |
1 | \input texinfo @c -*-texinfo-*- |
2 | @c Copyright 1988-1999 | |
3 | @c Free Software Foundation, Inc. | |
4 | @c | |
5 | @c %**start of header | |
6 | @c makeinfo ignores cmds prev to setfilename, so its arg cannot make use | |
7 | @c of @set vars. However, you can override filename with makeinfo -o. | |
8 | @setfilename gdb.info | |
9 | @c | |
10 | @include gdb-cfg.texi | |
11 | @c | |
c906108c | 12 | @settitle Debugging with @value{GDBN} |
c906108c SS |
13 | @setchapternewpage odd |
14 | @c %**end of header | |
15 | ||
16 | @iftex | |
17 | @c @smallbook | |
18 | @c @cropmarks | |
19 | @end iftex | |
20 | ||
21 | @finalout | |
22 | @syncodeindex ky cp | |
23 | ||
24 | @c readline appendices use @vindex | |
25 | @syncodeindex vr cp | |
26 | ||
27 | @c !!set GDB manual's edition---not the same as GDB version! | |
28 | @set EDITION Seventh | |
29 | ||
30 | @c !!set GDB manual's revision date | |
31 | @set DATE February 1999 | |
32 | ||
33 | @c THIS MANUAL REQUIRES TEXINFO-2 macros and info-makers to format properly. | |
34 | ||
35 | @ifinfo | |
36 | @c This is a dir.info fragment to support semi-automated addition of | |
37 | @c manuals to an info tree. zoo@cygnus.com is developing this facility. | |
38 | @format | |
39 | START-INFO-DIR-ENTRY | |
40 | * Gdb: (gdb). The @sc{gnu} debugger. | |
41 | END-INFO-DIR-ENTRY | |
42 | @end format | |
43 | @end ifinfo | |
44 | @c | |
45 | @c | |
46 | @ifinfo | |
47 | This file documents the @sc{gnu} debugger @value{GDBN}. | |
48 | ||
49 | ||
50 | This is the @value{EDITION} Edition, @value{DATE}, | |
51 | of @cite{Debugging with @value{GDBN}: the @sc{gnu} Source-Level Debugger} | |
52 | for @value{GDBN} Version @value{GDBVN}. | |
53 | ||
54 | Copyright (C) 1988-1999 Free Software Foundation, Inc. | |
55 | ||
56 | Permission is granted to make and distribute verbatim copies of | |
57 | this manual provided the copyright notice and this permission notice | |
58 | are preserved on all copies. | |
59 | ||
60 | @ignore | |
61 | Permission is granted to process this file through TeX and print the | |
62 | results, provided the printed document carries copying permission | |
63 | notice identical to this one except for the removal of this paragraph | |
64 | (this paragraph not being relevant to the printed manual). | |
65 | ||
66 | @end ignore | |
67 | Permission is granted to copy and distribute modified versions of this | |
68 | manual under the conditions for verbatim copying, provided also that the | |
69 | entire resulting derived work is distributed under the terms of a | |
70 | permission notice identical to this one. | |
71 | ||
72 | Permission is granted to copy and distribute translations of this manual | |
73 | into another language, under the above conditions for modified versions. | |
74 | @end ifinfo | |
75 | ||
76 | @titlepage | |
77 | @title Debugging with @value{GDBN} | |
78 | @subtitle The @sc{gnu} Source-Level Debugger | |
c906108c | 79 | @sp 1 |
c906108c SS |
80 | @subtitle @value{EDITION} Edition, for @value{GDBN} version @value{GDBVN} |
81 | @subtitle @value{DATE} | |
82 | @author Richard M. Stallman and Roland H. Pesch | |
c906108c | 83 | @page |
c906108c SS |
84 | @tex |
85 | {\parskip=0pt | |
53a5351d | 86 | \hfill (Send bugs and comments on @value{GDBN} to bug-gdb\@gnu.org.)\par |
c906108c SS |
87 | \hfill {\it Debugging with @value{GDBN}}\par |
88 | \hfill \TeX{}info \texinfoversion\par | |
89 | } | |
90 | @end tex | |
53a5351d JM |
91 | |
92 | @c ISBN seems to be wrong... | |
c906108c SS |
93 | |
94 | @vskip 0pt plus 1filll | |
95 | Copyright @copyright{} 1988-1999 Free Software Foundation, Inc. | |
96 | @sp 2 | |
c906108c SS |
97 | Published by the Free Software Foundation @* |
98 | 59 Temple Place - Suite 330, @* | |
99 | Boston, MA 02111-1307 USA @* | |
100 | Printed copies are available for $20 each. @* | |
101 | ISBN 1-882114-11-6 @* | |
c906108c SS |
102 | |
103 | Permission is granted to make and distribute verbatim copies of | |
104 | this manual provided the copyright notice and this permission notice | |
105 | are preserved on all copies. | |
106 | ||
107 | Permission is granted to copy and distribute modified versions of this | |
108 | manual under the conditions for verbatim copying, provided also that the | |
109 | entire resulting derived work is distributed under the terms of a | |
110 | permission notice identical to this one. | |
111 | ||
112 | Permission is granted to copy and distribute translations of this manual | |
113 | into another language, under the above conditions for modified versions. | |
114 | @end titlepage | |
115 | @page | |
116 | ||
117 | @ifinfo | |
53a5351d | 118 | @node Top |
c906108c SS |
119 | @top Debugging with @value{GDBN} |
120 | ||
121 | This file describes @value{GDBN}, the @sc{gnu} symbolic debugger. | |
122 | ||
123 | This is the @value{EDITION} Edition, @value{DATE}, for @value{GDBN} Version | |
124 | @value{GDBVN}. | |
125 | ||
126 | Copyright (C) 1988-1999 Free Software Foundation, Inc. | |
127 | @menu | |
128 | * Summary:: Summary of @value{GDBN} | |
c906108c | 129 | * Sample Session:: A sample @value{GDBN} session |
c906108c SS |
130 | |
131 | * Invocation:: Getting in and out of @value{GDBN} | |
132 | * Commands:: @value{GDBN} commands | |
133 | * Running:: Running programs under @value{GDBN} | |
134 | * Stopping:: Stopping and continuing | |
135 | * Stack:: Examining the stack | |
136 | * Source:: Examining source files | |
137 | * Data:: Examining data | |
c906108c | 138 | |
7a292a7a | 139 | * Languages:: Using @value{GDBN} with different languages |
c906108c SS |
140 | |
141 | * Symbols:: Examining the symbol table | |
142 | * Altering:: Altering execution | |
143 | * GDB Files:: @value{GDBN} files | |
144 | * Targets:: Specifying a debugging target | |
104c1213 | 145 | * Configurations:: Configuration-specific information |
c906108c SS |
146 | * Controlling GDB:: Controlling @value{GDBN} |
147 | * Sequences:: Canned sequences of commands | |
c906108c | 148 | * Emacs:: Using @value{GDBN} under @sc{gnu} Emacs |
c906108c SS |
149 | |
150 | * GDB Bugs:: Reporting bugs in @value{GDBN} | |
c906108c | 151 | * Formatting Documentation:: How to format and print @value{GDBN} documentation |
c906108c SS |
152 | |
153 | * Command Line Editing:: Command Line Editing | |
154 | * Using History Interactively:: Using History Interactively | |
155 | * Installing GDB:: Installing GDB | |
156 | * Index:: Index | |
c906108c SS |
157 | @end menu |
158 | ||
159 | @end ifinfo | |
160 | ||
53a5351d | 161 | @node Summary |
c906108c SS |
162 | @unnumbered Summary of @value{GDBN} |
163 | ||
164 | The purpose of a debugger such as @value{GDBN} is to allow you to see what is | |
165 | going on ``inside'' another program while it executes---or what another | |
166 | program was doing at the moment it crashed. | |
167 | ||
168 | @value{GDBN} can do four main kinds of things (plus other things in support of | |
169 | these) to help you catch bugs in the act: | |
170 | ||
171 | @itemize @bullet | |
172 | @item | |
173 | Start your program, specifying anything that might affect its behavior. | |
174 | ||
175 | @item | |
176 | Make your program stop on specified conditions. | |
177 | ||
178 | @item | |
179 | Examine what has happened, when your program has stopped. | |
180 | ||
181 | @item | |
182 | Change things in your program, so you can experiment with correcting the | |
183 | effects of one bug and go on to learn about another. | |
184 | @end itemize | |
185 | ||
cce74817 | 186 | You can use @value{GDBN} to debug programs written in C and C++. |
c906108c | 187 | For more information, see @ref{Support,,Supported languages}. |
c906108c SS |
188 | For more information, see @ref{C,,C and C++}. |
189 | ||
cce74817 JM |
190 | @cindex Chill |
191 | @cindex Modula-2 | |
c906108c | 192 | Support for Modula-2 and Chill is partial. For information on Modula-2, |
cce74817 | 193 | see @ref{Modula-2,,Modula-2}. For information on Chill, see @ref{Chill}. |
c906108c | 194 | |
cce74817 JM |
195 | @cindex Pascal |
196 | Debugging Pascal programs which use sets, subranges, file variables, or | |
197 | nested functions does not currently work. @value{GDBN} does not support | |
198 | entering expressions, printing values, or similar features using Pascal | |
199 | syntax. | |
c906108c | 200 | |
c906108c SS |
201 | @cindex Fortran |
202 | @value{GDBN} can be used to debug programs written in Fortran, although | |
53a5351d | 203 | it may be necessary to refer to some variables with a trailing |
cce74817 | 204 | underscore. |
c906108c | 205 | |
c906108c SS |
206 | @menu |
207 | * Free Software:: Freely redistributable software | |
208 | * Contributors:: Contributors to GDB | |
209 | @end menu | |
210 | ||
53a5351d | 211 | @node Free Software |
c906108c SS |
212 | @unnumberedsec Free software |
213 | ||
214 | @value{GDBN} is @dfn{free software}, protected by the @sc{gnu} | |
215 | General Public License | |
216 | (GPL). The GPL gives you the freedom to copy or adapt a licensed | |
217 | program---but every person getting a copy also gets with it the | |
218 | freedom to modify that copy (which means that they must get access to | |
219 | the source code), and the freedom to distribute further copies. | |
220 | Typical software companies use copyrights to limit your freedoms; the | |
221 | Free Software Foundation uses the GPL to preserve these freedoms. | |
222 | ||
223 | Fundamentally, the General Public License is a license which says that | |
224 | you have these freedoms and that you cannot take these freedoms away | |
225 | from anyone else. | |
226 | ||
53a5351d | 227 | @node Contributors |
c906108c SS |
228 | @unnumberedsec Contributors to GDB |
229 | ||
230 | Richard Stallman was the original author of GDB, and of many other | |
231 | @sc{gnu} programs. Many others have contributed to its development. | |
232 | This section attempts to credit major contributors. One of the virtues | |
233 | of free software is that everyone is free to contribute to it; with | |
234 | regret, we cannot actually acknowledge everyone here. The file | |
235 | @file{ChangeLog} in the @value{GDBN} distribution approximates a | |
236 | blow-by-blow account. | |
237 | ||
238 | Changes much prior to version 2.0 are lost in the mists of time. | |
239 | ||
240 | @quotation | |
241 | @emph{Plea:} Additions to this section are particularly welcome. If you | |
242 | or your friends (or enemies, to be evenhanded) have been unfairly | |
243 | omitted from this list, we would like to add your names! | |
244 | @end quotation | |
245 | ||
246 | So that they may not regard their many labors as thankless, we | |
247 | particularly thank those who shepherded @value{GDBN} through major | |
248 | releases: | |
249 | Jim Blandy (release 4.18); | |
250 | Jason Molenda (release 4.17); | |
251 | Stan Shebs (release 4.14); | |
252 | Fred Fish (releases 4.16, 4.15, 4.13, 4.12, 4.11, 4.10, and 4.9); | |
253 | Stu Grossman and John Gilmore (releases 4.8, 4.7, 4.6, 4.5, and 4.4); | |
254 | John Gilmore (releases 4.3, 4.2, 4.1, 4.0, and 3.9); | |
255 | Jim Kingdon (releases 3.5, 3.4, and 3.3); | |
256 | and Randy Smith (releases 3.2, 3.1, and 3.0). | |
257 | ||
258 | Richard Stallman, assisted at various times by Peter TerMaat, Chris | |
259 | Hanson, and Richard Mlynarik, handled releases through 2.8. | |
260 | ||
c906108c SS |
261 | Michael Tiemann is the author of most of the @sc{gnu} C++ support in GDB, |
262 | with significant additional contributions from Per Bothner. James | |
263 | Clark wrote the @sc{gnu} C++ demangler. Early work on C++ was by Peter | |
264 | TerMaat (who also did much general update work leading to release 3.0). | |
c906108c SS |
265 | |
266 | @value{GDBN} 4 uses the BFD subroutine library to examine multiple | |
267 | object-file formats; BFD was a joint project of David V. | |
268 | Henkel-Wallace, Rich Pixley, Steve Chamberlain, and John Gilmore. | |
269 | ||
270 | David Johnson wrote the original COFF support; Pace Willison did | |
271 | the original support for encapsulated COFF. | |
272 | ||
273 | Brent Benson of Harris Computer Systems contributed DWARF 2 support. | |
274 | ||
275 | Adam de Boor and Bradley Davis contributed the ISI Optimum V support. | |
276 | Per Bothner, Noboyuki Hikichi, and Alessandro Forin contributed MIPS | |
277 | support. | |
278 | Jean-Daniel Fekete contributed Sun 386i support. | |
279 | Chris Hanson improved the HP9000 support. | |
280 | Noboyuki Hikichi and Tomoyuki Hasei contributed Sony/News OS 3 support. | |
281 | David Johnson contributed Encore Umax support. | |
282 | Jyrki Kuoppala contributed Altos 3068 support. | |
283 | Jeff Law contributed HP PA and SOM support. | |
284 | Keith Packard contributed NS32K support. | |
285 | Doug Rabson contributed Acorn Risc Machine support. | |
286 | Bob Rusk contributed Harris Nighthawk CX-UX support. | |
287 | Chris Smith contributed Convex support (and Fortran debugging). | |
288 | Jonathan Stone contributed Pyramid support. | |
289 | Michael Tiemann contributed SPARC support. | |
290 | Tim Tucker contributed support for the Gould NP1 and Gould Powernode. | |
291 | Pace Willison contributed Intel 386 support. | |
292 | Jay Vosburgh contributed Symmetry support. | |
293 | ||
294 | Andreas Schwab contributed M68K Linux support. | |
295 | ||
296 | Rich Schaefer and Peter Schauer helped with support of SunOS shared | |
297 | libraries. | |
298 | ||
299 | Jay Fenlason and Roland McGrath ensured that @value{GDBN} and GAS agree | |
300 | about several machine instruction sets. | |
301 | ||
302 | Patrick Duval, Ted Goldstein, Vikram Koka and Glenn Engel helped develop | |
303 | remote debugging. Intel Corporation, Wind River Systems, AMD, and ARM | |
304 | contributed remote debugging modules for the i960, VxWorks, A29K UDI, | |
305 | and RDI targets, respectively. | |
306 | ||
307 | Brian Fox is the author of the readline libraries providing | |
308 | command-line editing and command history. | |
309 | ||
7a292a7a SS |
310 | Andrew Beers of SUNY Buffalo wrote the language-switching code, the |
311 | Modula-2 support, and contributed the Languages chapter of this manual. | |
c906108c SS |
312 | |
313 | Fred Fish wrote most of the support for Unix System Vr4. | |
c906108c SS |
314 | He also enhanced the command-completion support to cover C++ overloaded |
315 | symbols. | |
c906108c SS |
316 | |
317 | Hitachi America, Ltd. sponsored the support for H8/300, H8/500, and | |
318 | Super-H processors. | |
319 | ||
320 | NEC sponsored the support for the v850, Vr4xxx, and Vr5xxx processors. | |
321 | ||
322 | Mitsubishi sponsored the support for D10V, D30V, and M32R/D processors. | |
323 | ||
324 | Toshiba sponsored the support for the TX39 Mips processor. | |
325 | ||
326 | Matsushita sponsored the support for the MN10200 and MN10300 processors. | |
327 | ||
328 | Fujitsu sponsored the support for SPARClite and FR30 processors | |
329 | ||
330 | Kung Hsu, Jeff Law, and Rick Sladkey added support for hardware | |
331 | watchpoints. | |
332 | ||
333 | Michael Snyder added support for tracepoints. | |
334 | ||
335 | Stu Grossman wrote gdbserver. | |
336 | ||
337 | Jim Kingdon, Peter Schauer, Ian Taylor, and Stu Grossman made | |
338 | nearly innumerable bug fixes and cleanups throughout GDB. | |
339 | ||
340 | The following people at the Hewlett-Packard Company contributed | |
341 | support for the PA-RISC 2.0 architecture, HP-UX 10.20, 10.30, and 11.0 | |
342 | (narrow mode), HP's implementation of kernel threads, HP's aC++ | |
343 | compiler, and the terminal user interface: Ben Krepp, Richard Title, | |
344 | John Bishop, Susan Macchia, Kathy Mann, Satish Pai, India Paul, Steve | |
345 | Rehrauer, and Elena Zannoni. Kim Haase provided HP-specific | |
346 | information in this manual. | |
347 | ||
348 | Cygnus Solutions has sponsored GDB maintenance and much of its | |
349 | development since 1991. Cygnus engineers who have worked on GDB | |
2df3850c JM |
350 | fulltime include Mark Alexander, Jim Blandy, Per Bothner, Kevin |
351 | Buettner, Edith Epstein, Chris Faylor, Fred Fish, Martin Hunt, Jim | |
352 | Ingham, John Gilmore, Stu Grossman, Kung Hsu, Jim Kingdon, John Metzler, | |
353 | Fernando Nasser, Geoffrey Noer, Dawn Perchik, Rich Pixley, Zdenek | |
354 | Radouch, Keith Seitz, Stan Shebs, David Taylor, and Elena Zannoni. In | |
355 | addition, Dave Brolley, Ian Carmichael, Steve Chamberlain, Nick Clifton, | |
356 | JT Conklin, Stan Cox, DJ Delorie, Ulrich Drepper, Frank Eigler, Doug | |
357 | Evans, Sean Fagan, David Henkel-Wallace, Richard Henderson, Jeff | |
358 | Holcomb, Jeff Law, Jim Lemke, Tom Lord, Bob Manson, Michael Meissner, | |
359 | Jason Merrill, Catherine Moore, Drew Moseley, Ken Raeburn, Gavin | |
360 | Romig-Koch, Rob Savoye, Jamie Smith, Mike Stump, Ian Taylor, Angela | |
361 | Thomas, Michael Tiemann, Tom Tromey, Ron Unrau, Jim Wilson, and David | |
362 | Zuhn have made contributions both large and small. | |
c906108c SS |
363 | |
364 | ||
53a5351d | 365 | @node Sample Session |
c906108c SS |
366 | @chapter A Sample @value{GDBN} Session |
367 | ||
368 | You can use this manual at your leisure to read all about @value{GDBN}. | |
369 | However, a handful of commands are enough to get started using the | |
370 | debugger. This chapter illustrates those commands. | |
371 | ||
372 | @iftex | |
373 | In this sample session, we emphasize user input like this: @b{input}, | |
374 | to make it easier to pick out from the surrounding output. | |
375 | @end iftex | |
376 | ||
377 | @c FIXME: this example may not be appropriate for some configs, where | |
378 | @c FIXME...primary interest is in remote use. | |
379 | ||
380 | One of the preliminary versions of @sc{gnu} @code{m4} (a generic macro | |
381 | processor) exhibits the following bug: sometimes, when we change its | |
382 | quote strings from the default, the commands used to capture one macro | |
383 | definition within another stop working. In the following short @code{m4} | |
384 | session, we define a macro @code{foo} which expands to @code{0000}; we | |
385 | then use the @code{m4} built-in @code{defn} to define @code{bar} as the | |
386 | same thing. However, when we change the open quote string to | |
387 | @code{<QUOTE>} and the close quote string to @code{<UNQUOTE>}, the same | |
388 | procedure fails to define a new synonym @code{baz}: | |
389 | ||
390 | @smallexample | |
391 | $ @b{cd gnu/m4} | |
392 | $ @b{./m4} | |
393 | @b{define(foo,0000)} | |
394 | ||
395 | @b{foo} | |
396 | 0000 | |
397 | @b{define(bar,defn(`foo'))} | |
398 | ||
399 | @b{bar} | |
400 | 0000 | |
401 | @b{changequote(<QUOTE>,<UNQUOTE>)} | |
402 | ||
403 | @b{define(baz,defn(<QUOTE>foo<UNQUOTE>))} | |
404 | @b{baz} | |
405 | @b{C-d} | |
406 | m4: End of input: 0: fatal error: EOF in string | |
407 | @end smallexample | |
408 | ||
409 | @noindent | |
410 | Let us use @value{GDBN} to try to see what is going on. | |
411 | ||
c906108c SS |
412 | @smallexample |
413 | $ @b{@value{GDBP} m4} | |
414 | @c FIXME: this falsifies the exact text played out, to permit smallbook | |
415 | @c FIXME... format to come out better. | |
416 | @value{GDBN} is free software and you are welcome to distribute copies | |
417 | of it under certain conditions; type "show copying" to see | |
418 | the conditions. | |
419 | There is absolutely no warranty for @value{GDBN}; type "show warranty" | |
420 | for details. | |
421 | ||
422 | @value{GDBN} @value{GDBVN}, Copyright 1999 Free Software Foundation, Inc... | |
423 | (@value{GDBP}) | |
424 | @end smallexample | |
c906108c SS |
425 | |
426 | @noindent | |
427 | @value{GDBN} reads only enough symbol data to know where to find the | |
428 | rest when needed; as a result, the first prompt comes up very quickly. | |
429 | We now tell @value{GDBN} to use a narrower display width than usual, so | |
430 | that examples fit in this manual. | |
431 | ||
432 | @smallexample | |
433 | (@value{GDBP}) @b{set width 70} | |
434 | @end smallexample | |
435 | ||
436 | @noindent | |
437 | We need to see how the @code{m4} built-in @code{changequote} works. | |
438 | Having looked at the source, we know the relevant subroutine is | |
439 | @code{m4_changequote}, so we set a breakpoint there with the @value{GDBN} | |
440 | @code{break} command. | |
441 | ||
442 | @smallexample | |
443 | (@value{GDBP}) @b{break m4_changequote} | |
444 | Breakpoint 1 at 0x62f4: file builtin.c, line 879. | |
445 | @end smallexample | |
446 | ||
447 | @noindent | |
448 | Using the @code{run} command, we start @code{m4} running under @value{GDBN} | |
449 | control; as long as control does not reach the @code{m4_changequote} | |
450 | subroutine, the program runs as usual: | |
451 | ||
452 | @smallexample | |
453 | (@value{GDBP}) @b{run} | |
454 | Starting program: /work/Editorial/gdb/gnu/m4/m4 | |
455 | @b{define(foo,0000)} | |
456 | ||
457 | @b{foo} | |
458 | 0000 | |
459 | @end smallexample | |
460 | ||
461 | @noindent | |
462 | To trigger the breakpoint, we call @code{changequote}. @value{GDBN} | |
463 | suspends execution of @code{m4}, displaying information about the | |
464 | context where it stops. | |
465 | ||
466 | @smallexample | |
467 | @b{changequote(<QUOTE>,<UNQUOTE>)} | |
468 | ||
469 | Breakpoint 1, m4_changequote (argc=3, argv=0x33c70) | |
470 | at builtin.c:879 | |
471 | 879 if (bad_argc(TOKEN_DATA_TEXT(argv[0]),argc,1,3)) | |
472 | @end smallexample | |
473 | ||
474 | @noindent | |
475 | Now we use the command @code{n} (@code{next}) to advance execution to | |
476 | the next line of the current function. | |
477 | ||
478 | @smallexample | |
479 | (@value{GDBP}) @b{n} | |
480 | 882 set_quotes((argc >= 2) ? TOKEN_DATA_TEXT(argv[1])\ | |
481 | : nil, | |
482 | @end smallexample | |
483 | ||
484 | @noindent | |
485 | @code{set_quotes} looks like a promising subroutine. We can go into it | |
486 | by using the command @code{s} (@code{step}) instead of @code{next}. | |
487 | @code{step} goes to the next line to be executed in @emph{any} | |
488 | subroutine, so it steps into @code{set_quotes}. | |
489 | ||
490 | @smallexample | |
491 | (@value{GDBP}) @b{s} | |
492 | set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>") | |
493 | at input.c:530 | |
494 | 530 if (lquote != def_lquote) | |
495 | @end smallexample | |
496 | ||
497 | @noindent | |
498 | The display that shows the subroutine where @code{m4} is now | |
499 | suspended (and its arguments) is called a stack frame display. It | |
500 | shows a summary of the stack. We can use the @code{backtrace} | |
501 | command (which can also be spelled @code{bt}), to see where we are | |
502 | in the stack as a whole: the @code{backtrace} command displays a | |
503 | stack frame for each active subroutine. | |
504 | ||
505 | @smallexample | |
506 | (@value{GDBP}) @b{bt} | |
507 | #0 set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>") | |
508 | at input.c:530 | |
509 | #1 0x6344 in m4_changequote (argc=3, argv=0x33c70) | |
510 | at builtin.c:882 | |
511 | #2 0x8174 in expand_macro (sym=0x33320) at macro.c:242 | |
512 | #3 0x7a88 in expand_token (obs=0x0, t=209696, td=0xf7fffa30) | |
513 | at macro.c:71 | |
514 | #4 0x79dc in expand_input () at macro.c:40 | |
515 | #5 0x2930 in main (argc=0, argv=0xf7fffb20) at m4.c:195 | |
516 | @end smallexample | |
517 | ||
518 | @noindent | |
519 | We step through a few more lines to see what happens. The first two | |
520 | times, we can use @samp{s}; the next two times we use @code{n} to avoid | |
521 | falling into the @code{xstrdup} subroutine. | |
522 | ||
523 | @smallexample | |
524 | (@value{GDBP}) @b{s} | |
525 | 0x3b5c 532 if (rquote != def_rquote) | |
526 | (@value{GDBP}) @b{s} | |
527 | 0x3b80 535 lquote = (lq == nil || *lq == '\0') ? \ | |
528 | def_lquote : xstrdup(lq); | |
529 | (@value{GDBP}) @b{n} | |
530 | 536 rquote = (rq == nil || *rq == '\0') ? def_rquote\ | |
531 | : xstrdup(rq); | |
532 | (@value{GDBP}) @b{n} | |
533 | 538 len_lquote = strlen(rquote); | |
534 | @end smallexample | |
535 | ||
536 | @noindent | |
537 | The last line displayed looks a little odd; we can examine the variables | |
538 | @code{lquote} and @code{rquote} to see if they are in fact the new left | |
539 | and right quotes we specified. We use the command @code{p} | |
540 | (@code{print}) to see their values. | |
541 | ||
542 | @smallexample | |
543 | (@value{GDBP}) @b{p lquote} | |
544 | $1 = 0x35d40 "<QUOTE>" | |
545 | (@value{GDBP}) @b{p rquote} | |
546 | $2 = 0x35d50 "<UNQUOTE>" | |
547 | @end smallexample | |
548 | ||
549 | @noindent | |
550 | @code{lquote} and @code{rquote} are indeed the new left and right quotes. | |
551 | To look at some context, we can display ten lines of source | |
552 | surrounding the current line with the @code{l} (@code{list}) command. | |
553 | ||
554 | @smallexample | |
555 | (@value{GDBP}) @b{l} | |
556 | 533 xfree(rquote); | |
557 | 534 | |
558 | 535 lquote = (lq == nil || *lq == '\0') ? def_lquote\ | |
559 | : xstrdup (lq); | |
560 | 536 rquote = (rq == nil || *rq == '\0') ? def_rquote\ | |
561 | : xstrdup (rq); | |
562 | 537 | |
563 | 538 len_lquote = strlen(rquote); | |
564 | 539 len_rquote = strlen(lquote); | |
565 | 540 @} | |
566 | 541 | |
567 | 542 void | |
568 | @end smallexample | |
569 | ||
570 | @noindent | |
571 | Let us step past the two lines that set @code{len_lquote} and | |
572 | @code{len_rquote}, and then examine the values of those variables. | |
573 | ||
574 | @smallexample | |
575 | (@value{GDBP}) @b{n} | |
576 | 539 len_rquote = strlen(lquote); | |
577 | (@value{GDBP}) @b{n} | |
578 | 540 @} | |
579 | (@value{GDBP}) @b{p len_lquote} | |
580 | $3 = 9 | |
581 | (@value{GDBP}) @b{p len_rquote} | |
582 | $4 = 7 | |
583 | @end smallexample | |
584 | ||
585 | @noindent | |
586 | That certainly looks wrong, assuming @code{len_lquote} and | |
587 | @code{len_rquote} are meant to be the lengths of @code{lquote} and | |
588 | @code{rquote} respectively. We can set them to better values using | |
589 | the @code{p} command, since it can print the value of | |
590 | any expression---and that expression can include subroutine calls and | |
591 | assignments. | |
592 | ||
593 | @smallexample | |
594 | (@value{GDBP}) @b{p len_lquote=strlen(lquote)} | |
595 | $5 = 7 | |
596 | (@value{GDBP}) @b{p len_rquote=strlen(rquote)} | |
597 | $6 = 9 | |
598 | @end smallexample | |
599 | ||
600 | @noindent | |
601 | Is that enough to fix the problem of using the new quotes with the | |
602 | @code{m4} built-in @code{defn}? We can allow @code{m4} to continue | |
603 | executing with the @code{c} (@code{continue}) command, and then try the | |
604 | example that caused trouble initially: | |
605 | ||
606 | @smallexample | |
607 | (@value{GDBP}) @b{c} | |
608 | Continuing. | |
609 | ||
610 | @b{define(baz,defn(<QUOTE>foo<UNQUOTE>))} | |
611 | ||
612 | baz | |
613 | 0000 | |
614 | @end smallexample | |
615 | ||
616 | @noindent | |
617 | Success! The new quotes now work just as well as the default ones. The | |
618 | problem seems to have been just the two typos defining the wrong | |
619 | lengths. We allow @code{m4} exit by giving it an EOF as input: | |
620 | ||
621 | @smallexample | |
622 | @b{C-d} | |
623 | Program exited normally. | |
624 | @end smallexample | |
625 | ||
626 | @noindent | |
627 | The message @samp{Program exited normally.} is from @value{GDBN}; it | |
628 | indicates @code{m4} has finished executing. We can end our @value{GDBN} | |
629 | session with the @value{GDBN} @code{quit} command. | |
630 | ||
631 | @smallexample | |
632 | (@value{GDBP}) @b{quit} | |
633 | @end smallexample | |
c906108c | 634 | |
53a5351d | 635 | @node Invocation |
c906108c SS |
636 | @chapter Getting In and Out of @value{GDBN} |
637 | ||
638 | This chapter discusses how to start @value{GDBN}, and how to get out of it. | |
639 | The essentials are: | |
640 | @itemize @bullet | |
641 | @item | |
53a5351d | 642 | type @samp{@value{GDBP}} to start @value{GDBN}. |
c906108c SS |
643 | @item |
644 | type @kbd{quit} or @kbd{C-d} to exit. | |
645 | @end itemize | |
646 | ||
647 | @menu | |
648 | * Invoking GDB:: How to start @value{GDBN} | |
649 | * Quitting GDB:: How to quit @value{GDBN} | |
650 | * Shell Commands:: How to use shell commands inside @value{GDBN} | |
651 | @end menu | |
652 | ||
53a5351d | 653 | @node Invoking GDB |
c906108c SS |
654 | @section Invoking @value{GDBN} |
655 | ||
c906108c SS |
656 | Invoke @value{GDBN} by running the program @code{@value{GDBP}}. Once started, |
657 | @value{GDBN} reads commands from the terminal until you tell it to exit. | |
658 | ||
659 | You can also run @code{@value{GDBP}} with a variety of arguments and options, | |
660 | to specify more of your debugging environment at the outset. | |
661 | ||
c906108c SS |
662 | The command-line options described here are designed |
663 | to cover a variety of situations; in some environments, some of these | |
664 | options may effectively be unavailable. | |
c906108c SS |
665 | |
666 | The most usual way to start @value{GDBN} is with one argument, | |
667 | specifying an executable program: | |
668 | ||
669 | @example | |
670 | @value{GDBP} @var{program} | |
671 | @end example | |
672 | ||
c906108c SS |
673 | @noindent |
674 | You can also start with both an executable program and a core file | |
675 | specified: | |
676 | ||
677 | @example | |
678 | @value{GDBP} @var{program} @var{core} | |
679 | @end example | |
680 | ||
681 | You can, instead, specify a process ID as a second argument, if you want | |
682 | to debug a running process: | |
683 | ||
684 | @example | |
685 | @value{GDBP} @var{program} 1234 | |
686 | @end example | |
687 | ||
688 | @noindent | |
689 | would attach @value{GDBN} to process @code{1234} (unless you also have a file | |
690 | named @file{1234}; @value{GDBN} does check for a core file first). | |
691 | ||
c906108c | 692 | Taking advantage of the second command-line argument requires a fairly |
2df3850c JM |
693 | complete operating system; when you use @value{GDBN} as a remote |
694 | debugger attached to a bare board, there may not be any notion of | |
695 | ``process'', and there is often no way to get a core dump. @value{GDBN} | |
696 | will warn you if it is unable to attach or to read core dumps. | |
c906108c SS |
697 | |
698 | You can run @code{gdb} without printing the front material, which describes | |
699 | @value{GDBN}'s non-warranty, by specifying @code{-silent}: | |
700 | ||
701 | @smallexample | |
702 | @value{GDBP} -silent | |
703 | @end smallexample | |
704 | ||
705 | @noindent | |
706 | You can further control how @value{GDBN} starts up by using command-line | |
707 | options. @value{GDBN} itself can remind you of the options available. | |
708 | ||
709 | @noindent | |
710 | Type | |
711 | ||
712 | @example | |
713 | @value{GDBP} -help | |
714 | @end example | |
715 | ||
716 | @noindent | |
717 | to display all available options and briefly describe their use | |
718 | (@samp{@value{GDBP} -h} is a shorter equivalent). | |
719 | ||
720 | All options and command line arguments you give are processed | |
721 | in sequential order. The order makes a difference when the | |
722 | @samp{-x} option is used. | |
723 | ||
724 | ||
725 | @menu | |
c906108c SS |
726 | * File Options:: Choosing files |
727 | * Mode Options:: Choosing modes | |
728 | @end menu | |
729 | ||
c906108c SS |
730 | @node File Options |
731 | @subsection Choosing files | |
732 | ||
2df3850c | 733 | When @value{GDBN} starts, it reads any arguments other than options as |
c906108c SS |
734 | specifying an executable file and core file (or process ID). This is |
735 | the same as if the arguments were specified by the @samp{-se} and | |
736 | @samp{-c} options respectively. (@value{GDBN} reads the first argument | |
737 | that does not have an associated option flag as equivalent to the | |
738 | @samp{-se} option followed by that argument; and the second argument | |
739 | that does not have an associated option flag, if any, as equivalent to | |
740 | the @samp{-c} option followed by that argument.) | |
7a292a7a SS |
741 | |
742 | If @value{GDBN} has not been configured to included core file support, | |
743 | such as for most embedded targets, then it will complain about a second | |
744 | argument and ignore it. | |
c906108c SS |
745 | |
746 | Many options have both long and short forms; both are shown in the | |
747 | following list. @value{GDBN} also recognizes the long forms if you truncate | |
748 | them, so long as enough of the option is present to be unambiguous. | |
749 | (If you prefer, you can flag option arguments with @samp{--} rather | |
750 | than @samp{-}, though we illustrate the more usual convention.) | |
751 | ||
752 | @table @code | |
753 | @item -symbols @var{file} | |
754 | @itemx -s @var{file} | |
755 | Read symbol table from file @var{file}. | |
756 | ||
757 | @item -exec @var{file} | |
758 | @itemx -e @var{file} | |
7a292a7a SS |
759 | Use file @var{file} as the executable file to execute when appropriate, |
760 | and for examining pure data in conjunction with a core dump. | |
c906108c SS |
761 | |
762 | @item -se @var{file} | |
763 | Read symbol table from file @var{file} and use it as the executable | |
764 | file. | |
765 | ||
c906108c SS |
766 | @item -core @var{file} |
767 | @itemx -c @var{file} | |
768 | Use file @var{file} as a core dump to examine. | |
769 | ||
770 | @item -c @var{number} | |
771 | Connect to process ID @var{number}, as with the @code{attach} command | |
772 | (unless there is a file in core-dump format named @var{number}, in which | |
773 | case @samp{-c} specifies that file as a core dump to read). | |
c906108c SS |
774 | |
775 | @item -command @var{file} | |
776 | @itemx -x @var{file} | |
777 | Execute @value{GDBN} commands from file @var{file}. @xref{Command | |
778 | Files,, Command files}. | |
779 | ||
780 | @item -directory @var{directory} | |
781 | @itemx -d @var{directory} | |
782 | Add @var{directory} to the path to search for source files. | |
783 | ||
c906108c SS |
784 | @item -m |
785 | @itemx -mapped | |
786 | @emph{Warning: this option depends on operating system facilities that are not | |
787 | supported on all systems.}@* | |
788 | If memory-mapped files are available on your system through the @code{mmap} | |
789 | system call, you can use this option | |
790 | to have @value{GDBN} write the symbols from your | |
791 | program into a reusable file in the current directory. If the program you are debugging is | |
792 | called @file{/tmp/fred}, the mapped symbol file is @file{./fred.syms}. | |
793 | Future @value{GDBN} debugging sessions notice the presence of this file, | |
794 | and can quickly map in symbol information from it, rather than reading | |
795 | the symbol table from the executable program. | |
796 | ||
797 | The @file{.syms} file is specific to the host machine where @value{GDBN} | |
798 | is run. It holds an exact image of the internal @value{GDBN} symbol | |
799 | table. It cannot be shared across multiple host platforms. | |
c906108c | 800 | |
c906108c SS |
801 | @item -r |
802 | @itemx -readnow | |
803 | Read each symbol file's entire symbol table immediately, rather than | |
804 | the default, which is to read it incrementally as it is needed. | |
805 | This makes startup slower, but makes future operations faster. | |
53a5351d | 806 | |
c906108c SS |
807 | @end table |
808 | ||
2df3850c | 809 | You typically combine the @code{-mapped} and @code{-readnow} options in |
c906108c | 810 | order to build a @file{.syms} file that contains complete symbol |
2df3850c JM |
811 | information. (@xref{Files,,Commands to specify files}, for information |
812 | on @file{.syms} files.) A simple @value{GDBN} invocation to do nothing | |
813 | but build a @file{.syms} file for future use is: | |
c906108c SS |
814 | |
815 | @example | |
2df3850c | 816 | gdb -batch -nx -mapped -readnow programname |
c906108c | 817 | @end example |
c906108c | 818 | |
53a5351d | 819 | @node Mode Options |
c906108c SS |
820 | @subsection Choosing modes |
821 | ||
822 | You can run @value{GDBN} in various alternative modes---for example, in | |
823 | batch mode or quiet mode. | |
824 | ||
825 | @table @code | |
826 | @item -nx | |
827 | @itemx -n | |
2df3850c JM |
828 | Do not execute commands found in any initialization files (normally |
829 | called @file{.gdbinit}, or @file{gdb.ini} on PCs). Normally, | |
830 | @value{GDBN} executes the commands in these files after all the command | |
831 | options and arguments have been processed. @xref{Command Files,,Command | |
832 | files}. | |
c906108c SS |
833 | |
834 | @item -quiet | |
835 | @itemx -q | |
836 | ``Quiet''. Do not print the introductory and copyright messages. These | |
837 | messages are also suppressed in batch mode. | |
838 | ||
839 | @item -batch | |
840 | Run in batch mode. Exit with status @code{0} after processing all the | |
841 | command files specified with @samp{-x} (and all commands from | |
842 | initialization files, if not inhibited with @samp{-n}). Exit with | |
843 | nonzero status if an error occurs in executing the @value{GDBN} commands | |
844 | in the command files. | |
845 | ||
2df3850c JM |
846 | Batch mode may be useful for running @value{GDBN} as a filter, for |
847 | example to download and run a program on another computer; in order to | |
848 | make this more useful, the message | |
c906108c SS |
849 | |
850 | @example | |
851 | Program exited normally. | |
852 | @end example | |
853 | ||
854 | @noindent | |
2df3850c JM |
855 | (which is ordinarily issued whenever a program running under |
856 | @value{GDBN} control terminates) is not issued when running in batch | |
857 | mode. | |
858 | ||
859 | @item -nowindows | |
860 | @itemx -nw | |
861 | ``No windows''. If @value{GDBN} comes with a graphical user interface | |
862 | (GUI) built in, then this option tells GDB to only use the command-line | |
863 | interface. If no GUI is available, this option has no effect. | |
864 | ||
865 | @item -windows | |
866 | @itemx -w | |
867 | If @value{GDBN} includes a GUI, then this option requires it to be | |
868 | used if possible. | |
c906108c SS |
869 | |
870 | @item -cd @var{directory} | |
871 | Run @value{GDBN} using @var{directory} as its working directory, | |
872 | instead of the current directory. | |
873 | ||
c906108c SS |
874 | @item -fullname |
875 | @itemx -f | |
7a292a7a SS |
876 | @sc{gnu} Emacs sets this option when it runs @value{GDBN} as a |
877 | subprocess. It tells @value{GDBN} to output the full file name and line | |
878 | number in a standard, recognizable fashion each time a stack frame is | |
879 | displayed (which includes each time your program stops). This | |
880 | recognizable format looks like two @samp{\032} characters, followed by | |
881 | the file name, line number and character position separated by colons, | |
882 | and a newline. The Emacs-to-@value{GDBN} interface program uses the two | |
883 | @samp{\032} characters as a signal to display the source code for the | |
884 | frame. | |
c906108c | 885 | |
2df3850c JM |
886 | @item -baud @var{bps} |
887 | @itemx -b @var{bps} | |
c906108c SS |
888 | Set the line speed (baud rate or bits per second) of any serial |
889 | interface used by @value{GDBN} for remote debugging. | |
c906108c SS |
890 | |
891 | @item -tty @var{device} | |
892 | Run using @var{device} for your program's standard input and output. | |
893 | @c FIXME: kingdon thinks there is more to -tty. Investigate. | |
c906108c | 894 | |
53a5351d JM |
895 | @c resolve the situation of these eventually |
896 | @c @item -tui | |
897 | @c Use a Terminal User Interface. For information, use your Web browser to | |
898 | @c read the file @file{TUI.html}, which is usually installed in the | |
899 | @c directory @code{/opt/langtools/wdb/doc} on HP-UX systems. Do not use | |
900 | @c this option if you run @value{GDBN} from Emacs (see @pxref{Emacs, ,Using | |
901 | @c @value{GDBN} under @sc{gnu} Emacs}). | |
902 | ||
903 | @c @item -xdb | |
904 | @c Run in XDB compatibility mode, allowing the use of certain XDB commands. | |
905 | @c For information, see the file @file{xdb_trans.html}, which is usually | |
906 | @c installed in the directory @code{/opt/langtools/wdb/doc} on HP-UX | |
907 | @c systems. | |
908 | ||
c906108c SS |
909 | @end table |
910 | ||
53a5351d | 911 | @node Quitting GDB |
c906108c SS |
912 | @section Quitting @value{GDBN} |
913 | @cindex exiting @value{GDBN} | |
914 | @cindex leaving @value{GDBN} | |
915 | ||
916 | @table @code | |
917 | @kindex quit @r{[}@var{expression}@r{]} | |
918 | @kindex q | |
919 | @item quit | |
920 | To exit @value{GDBN}, use the @code{quit} command (abbreviated @code{q}), or | |
921 | type an end-of-file character (usually @kbd{C-d}). If you do not supply | |
922 | @var{expression}, @value{GDBN} will terminate normally; otherwise it will | |
923 | terminate using the result of @var{expression} as the error code. | |
924 | @end table | |
925 | ||
926 | @cindex interrupt | |
927 | An interrupt (often @kbd{C-c}) does not exit from @value{GDBN}, but rather | |
928 | terminates the action of any @value{GDBN} command that is in progress and | |
929 | returns to @value{GDBN} command level. It is safe to type the interrupt | |
930 | character at any time because @value{GDBN} does not allow it to take effect | |
931 | until a time when it is safe. | |
932 | ||
c906108c SS |
933 | If you have been using @value{GDBN} to control an attached process or |
934 | device, you can release it with the @code{detach} command | |
935 | (@pxref{Attach, ,Debugging an already-running process}). | |
c906108c | 936 | |
53a5351d | 937 | @node Shell Commands |
c906108c SS |
938 | @section Shell commands |
939 | ||
940 | If you need to execute occasional shell commands during your | |
941 | debugging session, there is no need to leave or suspend @value{GDBN}; you can | |
942 | just use the @code{shell} command. | |
943 | ||
944 | @table @code | |
945 | @kindex shell | |
946 | @cindex shell escape | |
947 | @item shell @var{command string} | |
948 | Invoke a standard shell to execute @var{command string}. | |
c906108c | 949 | If it exists, the environment variable @code{SHELL} determines which |
d4f3574e SS |
950 | shell to run. Otherwise @value{GDBN} uses the default shell |
951 | (@file{/bin/sh} on Unix systems, @file{COMMAND.COM} on MS-DOS, etc.). | |
c906108c SS |
952 | @end table |
953 | ||
954 | The utility @code{make} is often needed in development environments. | |
955 | You do not have to use the @code{shell} command for this purpose in | |
956 | @value{GDBN}: | |
957 | ||
958 | @table @code | |
959 | @kindex make | |
960 | @cindex calling make | |
961 | @item make @var{make-args} | |
962 | Execute the @code{make} program with the specified | |
963 | arguments. This is equivalent to @samp{shell make @var{make-args}}. | |
964 | @end table | |
965 | ||
53a5351d | 966 | @node Commands |
c906108c SS |
967 | @chapter @value{GDBN} Commands |
968 | ||
969 | You can abbreviate a @value{GDBN} command to the first few letters of the command | |
970 | name, if that abbreviation is unambiguous; and you can repeat certain | |
971 | @value{GDBN} commands by typing just @key{RET}. You can also use the @key{TAB} | |
972 | key to get @value{GDBN} to fill out the rest of a word in a command (or to | |
973 | show you the alternatives available, if there is more than one possibility). | |
974 | ||
975 | @menu | |
976 | * Command Syntax:: How to give commands to @value{GDBN} | |
977 | * Completion:: Command completion | |
978 | * Help:: How to ask @value{GDBN} for help | |
979 | @end menu | |
980 | ||
53a5351d | 981 | @node Command Syntax |
c906108c SS |
982 | @section Command syntax |
983 | ||
984 | A @value{GDBN} command is a single line of input. There is no limit on | |
985 | how long it can be. It starts with a command name, which is followed by | |
986 | arguments whose meaning depends on the command name. For example, the | |
987 | command @code{step} accepts an argument which is the number of times to | |
988 | step, as in @samp{step 5}. You can also use the @code{step} command | |
989 | with no arguments. Some command names do not allow any arguments. | |
990 | ||
991 | @cindex abbreviation | |
992 | @value{GDBN} command names may always be truncated if that abbreviation is | |
993 | unambiguous. Other possible command abbreviations are listed in the | |
994 | documentation for individual commands. In some cases, even ambiguous | |
995 | abbreviations are allowed; for example, @code{s} is specially defined as | |
996 | equivalent to @code{step} even though there are other commands whose | |
997 | names start with @code{s}. You can test abbreviations by using them as | |
998 | arguments to the @code{help} command. | |
999 | ||
1000 | @cindex repeating commands | |
1001 | @kindex RET | |
1002 | A blank line as input to @value{GDBN} (typing just @key{RET}) means to | |
1003 | repeat the previous command. Certain commands (for example, @code{run}) | |
1004 | will not repeat this way; these are commands whose unintentional | |
1005 | repetition might cause trouble and which you are unlikely to want to | |
1006 | repeat. | |
1007 | ||
1008 | The @code{list} and @code{x} commands, when you repeat them with | |
1009 | @key{RET}, construct new arguments rather than repeating | |
1010 | exactly as typed. This permits easy scanning of source or memory. | |
1011 | ||
1012 | @value{GDBN} can also use @key{RET} in another way: to partition lengthy | |
1013 | output, in a way similar to the common utility @code{more} | |
1014 | (@pxref{Screen Size,,Screen size}). Since it is easy to press one | |
1015 | @key{RET} too many in this situation, @value{GDBN} disables command | |
1016 | repetition after any command that generates this sort of display. | |
1017 | ||
1018 | @kindex # | |
1019 | @cindex comment | |
1020 | Any text from a @kbd{#} to the end of the line is a comment; it does | |
1021 | nothing. This is useful mainly in command files (@pxref{Command | |
1022 | Files,,Command files}). | |
1023 | ||
53a5351d | 1024 | @node Completion |
c906108c SS |
1025 | @section Command completion |
1026 | ||
1027 | @cindex completion | |
1028 | @cindex word completion | |
1029 | @value{GDBN} can fill in the rest of a word in a command for you, if there is | |
1030 | only one possibility; it can also show you what the valid possibilities | |
1031 | are for the next word in a command, at any time. This works for @value{GDBN} | |
1032 | commands, @value{GDBN} subcommands, and the names of symbols in your program. | |
1033 | ||
1034 | Press the @key{TAB} key whenever you want @value{GDBN} to fill out the rest | |
1035 | of a word. If there is only one possibility, @value{GDBN} fills in the | |
1036 | word, and waits for you to finish the command (or press @key{RET} to | |
1037 | enter it). For example, if you type | |
1038 | ||
1039 | @c FIXME "@key" does not distinguish its argument sufficiently to permit | |
1040 | @c complete accuracy in these examples; space introduced for clarity. | |
1041 | @c If texinfo enhancements make it unnecessary, it would be nice to | |
1042 | @c replace " @key" by "@key" in the following... | |
1043 | @example | |
1044 | (@value{GDBP}) info bre @key{TAB} | |
1045 | @end example | |
1046 | ||
1047 | @noindent | |
1048 | @value{GDBN} fills in the rest of the word @samp{breakpoints}, since that is | |
1049 | the only @code{info} subcommand beginning with @samp{bre}: | |
1050 | ||
1051 | @example | |
1052 | (@value{GDBP}) info breakpoints | |
1053 | @end example | |
1054 | ||
1055 | @noindent | |
1056 | You can either press @key{RET} at this point, to run the @code{info | |
1057 | breakpoints} command, or backspace and enter something else, if | |
1058 | @samp{breakpoints} does not look like the command you expected. (If you | |
1059 | were sure you wanted @code{info breakpoints} in the first place, you | |
1060 | might as well just type @key{RET} immediately after @samp{info bre}, | |
1061 | to exploit command abbreviations rather than command completion). | |
1062 | ||
1063 | If there is more than one possibility for the next word when you press | |
1064 | @key{TAB}, @value{GDBN} sounds a bell. You can either supply more | |
1065 | characters and try again, or just press @key{TAB} a second time; | |
1066 | @value{GDBN} displays all the possible completions for that word. For | |
1067 | example, you might want to set a breakpoint on a subroutine whose name | |
1068 | begins with @samp{make_}, but when you type @kbd{b make_@key{TAB}} @value{GDBN} | |
1069 | just sounds the bell. Typing @key{TAB} again displays all the | |
1070 | function names in your program that begin with those characters, for | |
1071 | example: | |
1072 | ||
1073 | @example | |
1074 | (@value{GDBP}) b make_ @key{TAB} | |
1075 | @exdent @value{GDBN} sounds bell; press @key{TAB} again, to see: | |
1076 | make_a_section_from_file make_environ | |
1077 | make_abs_section make_function_type | |
1078 | make_blockvector make_pointer_type | |
1079 | make_cleanup make_reference_type | |
1080 | make_command make_symbol_completion_list | |
1081 | (@value{GDBP}) b make_ | |
1082 | @end example | |
1083 | ||
1084 | @noindent | |
1085 | After displaying the available possibilities, @value{GDBN} copies your | |
1086 | partial input (@samp{b make_} in the example) so you can finish the | |
1087 | command. | |
1088 | ||
1089 | If you just want to see the list of alternatives in the first place, you | |
1090 | can press @kbd{M-?} rather than pressing @key{TAB} twice. @kbd{M-?} | |
7a292a7a | 1091 | means @kbd{@key{META} ?}. You can type this either by holding down a |
c906108c | 1092 | key designated as the @key{META} shift on your keyboard (if there is |
7a292a7a | 1093 | one) while typing @kbd{?}, or as @key{ESC} followed by @kbd{?}. |
c906108c SS |
1094 | |
1095 | @cindex quotes in commands | |
1096 | @cindex completion of quoted strings | |
1097 | Sometimes the string you need, while logically a ``word'', may contain | |
7a292a7a SS |
1098 | parentheses or other characters that @value{GDBN} normally excludes from |
1099 | its notion of a word. To permit word completion to work in this | |
1100 | situation, you may enclose words in @code{'} (single quote marks) in | |
1101 | @value{GDBN} commands. | |
c906108c | 1102 | |
c906108c SS |
1103 | The most likely situation where you might need this is in typing the |
1104 | name of a C++ function. This is because C++ allows function overloading | |
1105 | (multiple definitions of the same function, distinguished by argument | |
1106 | type). For example, when you want to set a breakpoint you may need to | |
1107 | distinguish whether you mean the version of @code{name} that takes an | |
1108 | @code{int} parameter, @code{name(int)}, or the version that takes a | |
1109 | @code{float} parameter, @code{name(float)}. To use the word-completion | |
1110 | facilities in this situation, type a single quote @code{'} at the | |
1111 | beginning of the function name. This alerts @value{GDBN} that it may need to | |
1112 | consider more information than usual when you press @key{TAB} or | |
1113 | @kbd{M-?} to request word completion: | |
1114 | ||
1115 | @example | |
1116 | (@value{GDBP}) b 'bubble( @key{M-?} | |
1117 | bubble(double,double) bubble(int,int) | |
1118 | (@value{GDBP}) b 'bubble( | |
1119 | @end example | |
1120 | ||
1121 | In some cases, @value{GDBN} can tell that completing a name requires using | |
1122 | quotes. When this happens, @value{GDBN} inserts the quote for you (while | |
1123 | completing as much as it can) if you do not type the quote in the first | |
1124 | place: | |
1125 | ||
1126 | @example | |
1127 | (@value{GDBP}) b bub @key{TAB} | |
1128 | @exdent @value{GDBN} alters your input line to the following, and rings a bell: | |
1129 | (@value{GDBP}) b 'bubble( | |
1130 | @end example | |
1131 | ||
1132 | @noindent | |
1133 | In general, @value{GDBN} can tell that a quote is needed (and inserts it) if | |
1134 | you have not yet started typing the argument list when you ask for | |
1135 | completion on an overloaded symbol. | |
1136 | ||
d4f3574e | 1137 | For more information about overloaded functions, see @ref{C plus plus |
c906108c SS |
1138 | expressions, ,C++ expressions}. You can use the command @code{set |
1139 | overload-resolution off} to disable overload resolution; | |
d4f3574e | 1140 | see @ref{Debugging C plus plus, ,@value{GDBN} features for C++}. |
c906108c SS |
1141 | |
1142 | ||
53a5351d | 1143 | @node Help |
c906108c SS |
1144 | @section Getting help |
1145 | @cindex online documentation | |
1146 | @kindex help | |
1147 | ||
1148 | You can always ask @value{GDBN} itself for information on its commands, | |
1149 | using the command @code{help}. | |
1150 | ||
1151 | @table @code | |
1152 | @kindex h | |
1153 | @item help | |
1154 | @itemx h | |
1155 | You can use @code{help} (abbreviated @code{h}) with no arguments to | |
1156 | display a short list of named classes of commands: | |
1157 | ||
1158 | @smallexample | |
1159 | (@value{GDBP}) help | |
1160 | List of classes of commands: | |
1161 | ||
2df3850c | 1162 | aliases -- Aliases of other commands |
c906108c | 1163 | breakpoints -- Making program stop at certain points |
2df3850c | 1164 | data -- Examining data |
c906108c | 1165 | files -- Specifying and examining files |
2df3850c JM |
1166 | internals -- Maintenance commands |
1167 | obscure -- Obscure features | |
1168 | running -- Running the program | |
1169 | stack -- Examining the stack | |
c906108c SS |
1170 | status -- Status inquiries |
1171 | support -- Support facilities | |
2df3850c | 1172 | tracepoints -- Tracing of program execution without stopping the program |
c906108c | 1173 | user-defined -- User-defined commands |
c906108c SS |
1174 | |
1175 | Type "help" followed by a class name for a list of | |
1176 | commands in that class. | |
1177 | Type "help" followed by command name for full | |
1178 | documentation. | |
1179 | Command name abbreviations are allowed if unambiguous. | |
1180 | (@value{GDBP}) | |
1181 | @end smallexample | |
1182 | ||
1183 | @item help @var{class} | |
1184 | Using one of the general help classes as an argument, you can get a | |
1185 | list of the individual commands in that class. For example, here is the | |
1186 | help display for the class @code{status}: | |
1187 | ||
1188 | @smallexample | |
1189 | (@value{GDBP}) help status | |
1190 | Status inquiries. | |
1191 | ||
1192 | List of commands: | |
1193 | ||
1194 | @c Line break in "show" line falsifies real output, but needed | |
1195 | @c to fit in smallbook page size. | |
2df3850c JM |
1196 | info -- Generic command for showing things |
1197 | about the program being debugged | |
1198 | show -- Generic command for showing things | |
1199 | about the debugger | |
c906108c SS |
1200 | |
1201 | Type "help" followed by command name for full | |
1202 | documentation. | |
1203 | Command name abbreviations are allowed if unambiguous. | |
1204 | (@value{GDBP}) | |
1205 | @end smallexample | |
1206 | ||
1207 | @item help @var{command} | |
1208 | With a command name as @code{help} argument, @value{GDBN} displays a | |
1209 | short paragraph on how to use that command. | |
1210 | ||
1211 | @kindex complete | |
1212 | @item complete @var{args} | |
1213 | The @code{complete @var{args}} command lists all the possible completions | |
1214 | for the beginning of a command. Use @var{args} to specify the beginning of the | |
1215 | command you want completed. For example: | |
1216 | ||
1217 | @smallexample | |
1218 | complete i | |
1219 | @end smallexample | |
1220 | ||
1221 | @noindent results in: | |
1222 | ||
1223 | @smallexample | |
1224 | @group | |
2df3850c JM |
1225 | if |
1226 | ignore | |
c906108c SS |
1227 | info |
1228 | inspect | |
c906108c SS |
1229 | @end group |
1230 | @end smallexample | |
1231 | ||
1232 | @noindent This is intended for use by @sc{gnu} Emacs. | |
1233 | @end table | |
1234 | ||
1235 | In addition to @code{help}, you can use the @value{GDBN} commands @code{info} | |
1236 | and @code{show} to inquire about the state of your program, or the state | |
1237 | of @value{GDBN} itself. Each command supports many topics of inquiry; this | |
1238 | manual introduces each of them in the appropriate context. The listings | |
1239 | under @code{info} and under @code{show} in the Index point to | |
1240 | all the sub-commands. @xref{Index}. | |
1241 | ||
1242 | @c @group | |
1243 | @table @code | |
1244 | @kindex info | |
1245 | @kindex i | |
1246 | @item info | |
1247 | This command (abbreviated @code{i}) is for describing the state of your | |
1248 | program. For example, you can list the arguments given to your program | |
1249 | with @code{info args}, list the registers currently in use with @code{info | |
1250 | registers}, or list the breakpoints you have set with @code{info breakpoints}. | |
1251 | You can get a complete list of the @code{info} sub-commands with | |
1252 | @w{@code{help info}}. | |
1253 | ||
1254 | @kindex set | |
1255 | @item set | |
1256 | You can assign the result of an expression to an environment variable with | |
1257 | @code{set}. For example, you can set the @value{GDBN} prompt to a $-sign with | |
1258 | @code{set prompt $}. | |
1259 | ||
1260 | @kindex show | |
1261 | @item show | |
1262 | In contrast to @code{info}, @code{show} is for describing the state of | |
1263 | @value{GDBN} itself. | |
1264 | You can change most of the things you can @code{show}, by using the | |
1265 | related command @code{set}; for example, you can control what number | |
1266 | system is used for displays with @code{set radix}, or simply inquire | |
1267 | which is currently in use with @code{show radix}. | |
1268 | ||
1269 | @kindex info set | |
1270 | To display all the settable parameters and their current | |
1271 | values, you can use @code{show} with no arguments; you may also use | |
1272 | @code{info set}. Both commands produce the same display. | |
1273 | @c FIXME: "info set" violates the rule that "info" is for state of | |
1274 | @c FIXME...program. Ck w/ GNU: "info set" to be called something else, | |
1275 | @c FIXME...or change desc of rule---eg "state of prog and debugging session"? | |
1276 | @end table | |
1277 | @c @end group | |
1278 | ||
1279 | Here are three miscellaneous @code{show} subcommands, all of which are | |
1280 | exceptional in lacking corresponding @code{set} commands: | |
1281 | ||
1282 | @table @code | |
1283 | @kindex show version | |
1284 | @cindex version number | |
1285 | @item show version | |
1286 | Show what version of @value{GDBN} is running. You should include this | |
2df3850c JM |
1287 | information in @value{GDBN} bug-reports. If multiple versions of |
1288 | @value{GDBN} are in use at your site, you may need to determine which | |
1289 | version of @value{GDBN} you are running; as @value{GDBN} evolves, new | |
1290 | commands are introduced, and old ones may wither away. Also, many | |
1291 | system vendors ship variant versions of @value{GDBN}, and there are | |
1292 | variant versions of @value{GDBN} in GNU/Linux distributions as well. | |
1293 | The version number is the same as the one announced when you start | |
1294 | @value{GDBN}. | |
c906108c SS |
1295 | |
1296 | @kindex show copying | |
1297 | @item show copying | |
1298 | Display information about permission for copying @value{GDBN}. | |
1299 | ||
1300 | @kindex show warranty | |
1301 | @item show warranty | |
2df3850c JM |
1302 | Display the @sc{gnu} ``NO WARRANTY'' statement, or a warranty, |
1303 | if your version of @value{GDB} comes with one. | |
1304 | ||
c906108c SS |
1305 | @end table |
1306 | ||
53a5351d | 1307 | @node Running |
c906108c SS |
1308 | @chapter Running Programs Under @value{GDBN} |
1309 | ||
1310 | When you run a program under @value{GDBN}, you must first generate | |
1311 | debugging information when you compile it. | |
7a292a7a SS |
1312 | |
1313 | You may start @value{GDBN} with its arguments, if any, in an environment | |
1314 | of your choice. If you are doing native debugging, you may redirect | |
1315 | your program's input and output, debug an already running process, or | |
1316 | kill a child process. | |
c906108c SS |
1317 | |
1318 | @menu | |
1319 | * Compilation:: Compiling for debugging | |
1320 | * Starting:: Starting your program | |
c906108c SS |
1321 | * Arguments:: Your program's arguments |
1322 | * Environment:: Your program's environment | |
c906108c SS |
1323 | |
1324 | * Working Directory:: Your program's working directory | |
1325 | * Input/Output:: Your program's input and output | |
1326 | * Attach:: Debugging an already-running process | |
1327 | * Kill Process:: Killing the child process | |
c906108c SS |
1328 | |
1329 | * Threads:: Debugging programs with multiple threads | |
1330 | * Processes:: Debugging programs with multiple processes | |
1331 | @end menu | |
1332 | ||
53a5351d | 1333 | @node Compilation |
c906108c SS |
1334 | @section Compiling for debugging |
1335 | ||
1336 | In order to debug a program effectively, you need to generate | |
1337 | debugging information when you compile it. This debugging information | |
1338 | is stored in the object file; it describes the data type of each | |
1339 | variable or function and the correspondence between source line numbers | |
1340 | and addresses in the executable code. | |
1341 | ||
1342 | To request debugging information, specify the @samp{-g} option when you run | |
1343 | the compiler. | |
1344 | ||
1345 | Many C compilers are unable to handle the @samp{-g} and @samp{-O} | |
1346 | options together. Using those compilers, you cannot generate optimized | |
1347 | executables containing debugging information. | |
1348 | ||
53a5351d JM |
1349 | @value{NGCC}, the @sc{gnu} C compiler, supports @samp{-g} with or |
1350 | without @samp{-O}, making it possible to debug optimized code. We | |
1351 | recommend that you @emph{always} use @samp{-g} whenever you compile a | |
1352 | program. You may think your program is correct, but there is no sense | |
1353 | in pushing your luck. | |
c906108c SS |
1354 | |
1355 | @cindex optimized code, debugging | |
1356 | @cindex debugging optimized code | |
1357 | When you debug a program compiled with @samp{-g -O}, remember that the | |
1358 | optimizer is rearranging your code; the debugger shows you what is | |
1359 | really there. Do not be too surprised when the execution path does not | |
1360 | exactly match your source file! An extreme example: if you define a | |
1361 | variable, but never use it, @value{GDBN} never sees that | |
1362 | variable---because the compiler optimizes it out of existence. | |
1363 | ||
1364 | Some things do not work as well with @samp{-g -O} as with just | |
1365 | @samp{-g}, particularly on machines with instruction scheduling. If in | |
1366 | doubt, recompile with @samp{-g} alone, and if this fixes the problem, | |
1367 | please report it to us as a bug (including a test case!). | |
1368 | ||
1369 | Older versions of the @sc{gnu} C compiler permitted a variant option | |
1370 | @w{@samp{-gg}} for debugging information. @value{GDBN} no longer supports this | |
1371 | format; if your @sc{gnu} C compiler has this option, do not use it. | |
1372 | ||
1373 | @need 2000 | |
53a5351d | 1374 | @node Starting |
c906108c SS |
1375 | @section Starting your program |
1376 | @cindex starting | |
1377 | @cindex running | |
1378 | ||
1379 | @table @code | |
1380 | @kindex run | |
1381 | @item run | |
1382 | @itemx r | |
7a292a7a SS |
1383 | Use the @code{run} command to start your program under @value{GDBN}. |
1384 | You must first specify the program name (except on VxWorks) with an | |
1385 | argument to @value{GDBN} (@pxref{Invocation, ,Getting In and Out of | |
1386 | @value{GDBN}}), or by using the @code{file} or @code{exec-file} command | |
1387 | (@pxref{Files, ,Commands to specify files}). | |
c906108c SS |
1388 | |
1389 | @end table | |
1390 | ||
c906108c SS |
1391 | If you are running your program in an execution environment that |
1392 | supports processes, @code{run} creates an inferior process and makes | |
1393 | that process run your program. (In environments without processes, | |
1394 | @code{run} jumps to the start of your program.) | |
1395 | ||
1396 | The execution of a program is affected by certain information it | |
1397 | receives from its superior. @value{GDBN} provides ways to specify this | |
1398 | information, which you must do @emph{before} starting your program. (You | |
1399 | can change it after starting your program, but such changes only affect | |
1400 | your program the next time you start it.) This information may be | |
1401 | divided into four categories: | |
1402 | ||
1403 | @table @asis | |
1404 | @item The @emph{arguments.} | |
1405 | Specify the arguments to give your program as the arguments of the | |
1406 | @code{run} command. If a shell is available on your target, the shell | |
1407 | is used to pass the arguments, so that you may use normal conventions | |
1408 | (such as wildcard expansion or variable substitution) in describing | |
1409 | the arguments. | |
1410 | In Unix systems, you can control which shell is used with the | |
1411 | @code{SHELL} environment variable. | |
1412 | @xref{Arguments, ,Your program's arguments}. | |
1413 | ||
1414 | @item The @emph{environment.} | |
1415 | Your program normally inherits its environment from @value{GDBN}, but you can | |
1416 | use the @value{GDBN} commands @code{set environment} and @code{unset | |
1417 | environment} to change parts of the environment that affect | |
1418 | your program. @xref{Environment, ,Your program's environment}. | |
1419 | ||
1420 | @item The @emph{working directory.} | |
1421 | Your program inherits its working directory from @value{GDBN}. You can set | |
1422 | the @value{GDBN} working directory with the @code{cd} command in @value{GDBN}. | |
1423 | @xref{Working Directory, ,Your program's working directory}. | |
1424 | ||
1425 | @item The @emph{standard input and output.} | |
1426 | Your program normally uses the same device for standard input and | |
1427 | standard output as @value{GDBN} is using. You can redirect input and output | |
1428 | in the @code{run} command line, or you can use the @code{tty} command to | |
1429 | set a different device for your program. | |
1430 | @xref{Input/Output, ,Your program's input and output}. | |
1431 | ||
1432 | @cindex pipes | |
1433 | @emph{Warning:} While input and output redirection work, you cannot use | |
1434 | pipes to pass the output of the program you are debugging to another | |
1435 | program; if you attempt this, @value{GDBN} is likely to wind up debugging the | |
1436 | wrong program. | |
1437 | @end table | |
c906108c SS |
1438 | |
1439 | When you issue the @code{run} command, your program begins to execute | |
1440 | immediately. @xref{Stopping, ,Stopping and continuing}, for discussion | |
1441 | of how to arrange for your program to stop. Once your program has | |
1442 | stopped, you may call functions in your program, using the @code{print} | |
1443 | or @code{call} commands. @xref{Data, ,Examining Data}. | |
1444 | ||
1445 | If the modification time of your symbol file has changed since the last | |
1446 | time @value{GDBN} read its symbols, @value{GDBN} discards its symbol | |
1447 | table, and reads it again. When it does this, @value{GDBN} tries to retain | |
1448 | your current breakpoints. | |
1449 | ||
53a5351d | 1450 | @node Arguments |
c906108c SS |
1451 | @section Your program's arguments |
1452 | ||
1453 | @cindex arguments (to your program) | |
1454 | The arguments to your program can be specified by the arguments of the | |
1455 | @code{run} command. | |
1456 | They are passed to a shell, which expands wildcard characters and | |
1457 | performs redirection of I/O, and thence to your program. Your | |
1458 | @code{SHELL} environment variable (if it exists) specifies what shell | |
1459 | @value{GDBN} uses. If you do not define @code{SHELL}, @value{GDBN} uses | |
d4f3574e SS |
1460 | the default shell (@file{/bin/sh} on Unix). |
1461 | ||
1462 | On non-Unix systems, the program is usually invoked directly by | |
1463 | @value{GDBN}, which emulates I/O redirection via the appropriate system | |
1464 | calls, and the wildcard characters are expanded by the startup code of | |
1465 | the program, not by the shell. | |
c906108c SS |
1466 | |
1467 | @code{run} with no arguments uses the same arguments used by the previous | |
1468 | @code{run}, or those set by the @code{set args} command. | |
1469 | ||
1470 | @kindex set args | |
1471 | @table @code | |
1472 | @item set args | |
1473 | Specify the arguments to be used the next time your program is run. If | |
1474 | @code{set args} has no arguments, @code{run} executes your program | |
1475 | with no arguments. Once you have run your program with arguments, | |
1476 | using @code{set args} before the next @code{run} is the only way to run | |
1477 | it again without arguments. | |
1478 | ||
1479 | @kindex show args | |
1480 | @item show args | |
1481 | Show the arguments to give your program when it is started. | |
1482 | @end table | |
1483 | ||
53a5351d | 1484 | @node Environment |
c906108c SS |
1485 | @section Your program's environment |
1486 | ||
1487 | @cindex environment (of your program) | |
1488 | The @dfn{environment} consists of a set of environment variables and | |
1489 | their values. Environment variables conventionally record such things as | |
1490 | your user name, your home directory, your terminal type, and your search | |
1491 | path for programs to run. Usually you set up environment variables with | |
1492 | the shell and they are inherited by all the other programs you run. When | |
1493 | debugging, it can be useful to try running your program with a modified | |
1494 | environment without having to start @value{GDBN} over again. | |
1495 | ||
1496 | @table @code | |
1497 | @kindex path | |
1498 | @item path @var{directory} | |
1499 | Add @var{directory} to the front of the @code{PATH} environment variable | |
1500 | (the search path for executables), for both @value{GDBN} and your program. | |
d4f3574e SS |
1501 | You may specify several directory names, separated by whitespace or by a |
1502 | system-dependent separator character (@samp{:} on Unix, @samp{;} on | |
1503 | MS-DOS and MS-Windows). If @var{directory} is already in the path, it | |
1504 | is moved to the front, so it is searched sooner. | |
c906108c SS |
1505 | |
1506 | You can use the string @samp{$cwd} to refer to whatever is the current | |
1507 | working directory at the time @value{GDBN} searches the path. If you | |
1508 | use @samp{.} instead, it refers to the directory where you executed the | |
1509 | @code{path} command. @value{GDBN} replaces @samp{.} in the | |
1510 | @var{directory} argument (with the current path) before adding | |
1511 | @var{directory} to the search path. | |
1512 | @c 'path' is explicitly nonrepeatable, but RMS points out it is silly to | |
1513 | @c document that, since repeating it would be a no-op. | |
1514 | ||
1515 | @kindex show paths | |
1516 | @item show paths | |
1517 | Display the list of search paths for executables (the @code{PATH} | |
1518 | environment variable). | |
1519 | ||
1520 | @kindex show environment | |
1521 | @item show environment @r{[}@var{varname}@r{]} | |
1522 | Print the value of environment variable @var{varname} to be given to | |
1523 | your program when it starts. If you do not supply @var{varname}, | |
1524 | print the names and values of all environment variables to be given to | |
1525 | your program. You can abbreviate @code{environment} as @code{env}. | |
1526 | ||
1527 | @kindex set environment | |
53a5351d | 1528 | @item set environment @var{varname} @r{[}=@var{value}@r{]} |
c906108c SS |
1529 | Set environment variable @var{varname} to @var{value}. The value |
1530 | changes for your program only, not for @value{GDBN} itself. @var{value} may | |
1531 | be any string; the values of environment variables are just strings, and | |
1532 | any interpretation is supplied by your program itself. The @var{value} | |
1533 | parameter is optional; if it is eliminated, the variable is set to a | |
1534 | null value. | |
1535 | @c "any string" here does not include leading, trailing | |
1536 | @c blanks. Gnu asks: does anyone care? | |
1537 | ||
1538 | For example, this command: | |
1539 | ||
1540 | @example | |
1541 | set env USER = foo | |
1542 | @end example | |
1543 | ||
1544 | @noindent | |
d4f3574e | 1545 | tells the debugged program, when subsequently run, that its user is named |
c906108c SS |
1546 | @samp{foo}. (The spaces around @samp{=} are used for clarity here; they |
1547 | are not actually required.) | |
1548 | ||
1549 | @kindex unset environment | |
1550 | @item unset environment @var{varname} | |
1551 | Remove variable @var{varname} from the environment to be passed to your | |
1552 | program. This is different from @samp{set env @var{varname} =}; | |
1553 | @code{unset environment} removes the variable from the environment, | |
1554 | rather than assigning it an empty value. | |
1555 | @end table | |
1556 | ||
d4f3574e SS |
1557 | @emph{Warning:} On Unix systems, @value{GDBN} runs your program using |
1558 | the shell indicated | |
c906108c SS |
1559 | by your @code{SHELL} environment variable if it exists (or |
1560 | @code{/bin/sh} if not). If your @code{SHELL} variable names a shell | |
1561 | that runs an initialization file---such as @file{.cshrc} for C-shell, or | |
1562 | @file{.bashrc} for BASH---any variables you set in that file affect | |
1563 | your program. You may wish to move setting of environment variables to | |
1564 | files that are only run when you sign on, such as @file{.login} or | |
1565 | @file{.profile}. | |
1566 | ||
53a5351d | 1567 | @node Working Directory |
c906108c SS |
1568 | @section Your program's working directory |
1569 | ||
1570 | @cindex working directory (of your program) | |
1571 | Each time you start your program with @code{run}, it inherits its | |
1572 | working directory from the current working directory of @value{GDBN}. | |
1573 | The @value{GDBN} working directory is initially whatever it inherited | |
1574 | from its parent process (typically the shell), but you can specify a new | |
1575 | working directory in @value{GDBN} with the @code{cd} command. | |
1576 | ||
1577 | The @value{GDBN} working directory also serves as a default for the commands | |
1578 | that specify files for @value{GDBN} to operate on. @xref{Files, ,Commands to | |
1579 | specify files}. | |
1580 | ||
1581 | @table @code | |
1582 | @kindex cd | |
1583 | @item cd @var{directory} | |
1584 | Set the @value{GDBN} working directory to @var{directory}. | |
1585 | ||
1586 | @kindex pwd | |
1587 | @item pwd | |
1588 | Print the @value{GDBN} working directory. | |
1589 | @end table | |
1590 | ||
53a5351d | 1591 | @node Input/Output |
c906108c SS |
1592 | @section Your program's input and output |
1593 | ||
1594 | @cindex redirection | |
1595 | @cindex i/o | |
1596 | @cindex terminal | |
1597 | By default, the program you run under @value{GDBN} does input and output to | |
1598 | the same terminal that @value{GDBN} uses. @value{GDBN} switches the terminal | |
1599 | to its own terminal modes to interact with you, but it records the terminal | |
1600 | modes your program was using and switches back to them when you continue | |
1601 | running your program. | |
1602 | ||
1603 | @table @code | |
1604 | @kindex info terminal | |
1605 | @item info terminal | |
1606 | Displays information recorded by @value{GDBN} about the terminal modes your | |
1607 | program is using. | |
1608 | @end table | |
1609 | ||
1610 | You can redirect your program's input and/or output using shell | |
1611 | redirection with the @code{run} command. For example, | |
1612 | ||
1613 | @example | |
1614 | run > outfile | |
1615 | @end example | |
1616 | ||
1617 | @noindent | |
1618 | starts your program, diverting its output to the file @file{outfile}. | |
1619 | ||
1620 | @kindex tty | |
1621 | @cindex controlling terminal | |
1622 | Another way to specify where your program should do input and output is | |
1623 | with the @code{tty} command. This command accepts a file name as | |
1624 | argument, and causes this file to be the default for future @code{run} | |
1625 | commands. It also resets the controlling terminal for the child | |
1626 | process, for future @code{run} commands. For example, | |
1627 | ||
1628 | @example | |
1629 | tty /dev/ttyb | |
1630 | @end example | |
1631 | ||
1632 | @noindent | |
1633 | directs that processes started with subsequent @code{run} commands | |
1634 | default to do input and output on the terminal @file{/dev/ttyb} and have | |
1635 | that as their controlling terminal. | |
1636 | ||
1637 | An explicit redirection in @code{run} overrides the @code{tty} command's | |
1638 | effect on the input/output device, but not its effect on the controlling | |
1639 | terminal. | |
1640 | ||
1641 | When you use the @code{tty} command or redirect input in the @code{run} | |
1642 | command, only the input @emph{for your program} is affected. The input | |
1643 | for @value{GDBN} still comes from your terminal. | |
1644 | ||
53a5351d | 1645 | @node Attach |
c906108c SS |
1646 | @section Debugging an already-running process |
1647 | @kindex attach | |
1648 | @cindex attach | |
1649 | ||
1650 | @table @code | |
1651 | @item attach @var{process-id} | |
1652 | This command attaches to a running process---one that was started | |
1653 | outside @value{GDBN}. (@code{info files} shows your active | |
1654 | targets.) The command takes as argument a process ID. The usual way to | |
1655 | find out the process-id of a Unix process is with the @code{ps} utility, | |
1656 | or with the @samp{jobs -l} shell command. | |
1657 | ||
1658 | @code{attach} does not repeat if you press @key{RET} a second time after | |
1659 | executing the command. | |
1660 | @end table | |
1661 | ||
1662 | To use @code{attach}, your program must be running in an environment | |
1663 | which supports processes; for example, @code{attach} does not work for | |
1664 | programs on bare-board targets that lack an operating system. You must | |
1665 | also have permission to send the process a signal. | |
1666 | ||
1667 | When you use @code{attach}, the debugger finds the program running in | |
1668 | the process first by looking in the current working directory, then (if | |
1669 | the program is not found) by using the source file search path | |
1670 | (@pxref{Source Path, ,Specifying source directories}). You can also use | |
1671 | the @code{file} command to load the program. @xref{Files, ,Commands to | |
1672 | Specify Files}. | |
1673 | ||
1674 | The first thing @value{GDBN} does after arranging to debug the specified | |
1675 | process is to stop it. You can examine and modify an attached process | |
53a5351d JM |
1676 | with all the @value{GDBN} commands that are ordinarily available when |
1677 | you start processes with @code{run}. You can insert breakpoints; you | |
1678 | can step and continue; you can modify storage. If you would rather the | |
1679 | process continue running, you may use the @code{continue} command after | |
c906108c SS |
1680 | attaching @value{GDBN} to the process. |
1681 | ||
1682 | @table @code | |
1683 | @kindex detach | |
1684 | @item detach | |
1685 | When you have finished debugging the attached process, you can use the | |
1686 | @code{detach} command to release it from @value{GDBN} control. Detaching | |
1687 | the process continues its execution. After the @code{detach} command, | |
1688 | that process and @value{GDBN} become completely independent once more, and you | |
1689 | are ready to @code{attach} another process or start one with @code{run}. | |
1690 | @code{detach} does not repeat if you press @key{RET} again after | |
1691 | executing the command. | |
1692 | @end table | |
1693 | ||
1694 | If you exit @value{GDBN} or use the @code{run} command while you have an | |
1695 | attached process, you kill that process. By default, @value{GDBN} asks | |
1696 | for confirmation if you try to do either of these things; you can | |
1697 | control whether or not you need to confirm by using the @code{set | |
1698 | confirm} command (@pxref{Messages/Warnings, ,Optional warnings and | |
1699 | messages}). | |
1700 | ||
53a5351d | 1701 | @node Kill Process |
c906108c | 1702 | @section Killing the child process |
c906108c SS |
1703 | |
1704 | @table @code | |
1705 | @kindex kill | |
1706 | @item kill | |
1707 | Kill the child process in which your program is running under @value{GDBN}. | |
1708 | @end table | |
1709 | ||
1710 | This command is useful if you wish to debug a core dump instead of a | |
1711 | running process. @value{GDBN} ignores any core dump file while your program | |
1712 | is running. | |
1713 | ||
1714 | On some operating systems, a program cannot be executed outside @value{GDBN} | |
1715 | while you have breakpoints set on it inside @value{GDBN}. You can use the | |
1716 | @code{kill} command in this situation to permit running your program | |
1717 | outside the debugger. | |
1718 | ||
1719 | The @code{kill} command is also useful if you wish to recompile and | |
1720 | relink your program, since on many systems it is impossible to modify an | |
1721 | executable file while it is running in a process. In this case, when you | |
1722 | next type @code{run}, @value{GDBN} notices that the file has changed, and | |
1723 | reads the symbol table again (while trying to preserve your current | |
1724 | breakpoint settings). | |
1725 | ||
53a5351d | 1726 | @node Threads |
c906108c | 1727 | @section Debugging programs with multiple threads |
c906108c SS |
1728 | |
1729 | @cindex threads of execution | |
1730 | @cindex multiple threads | |
1731 | @cindex switching threads | |
1732 | In some operating systems, such as HP-UX and Solaris, a single program | |
1733 | may have more than one @dfn{thread} of execution. The precise semantics | |
1734 | of threads differ from one operating system to another, but in general | |
1735 | the threads of a single program are akin to multiple processes---except | |
1736 | that they share one address space (that is, they can all examine and | |
1737 | modify the same variables). On the other hand, each thread has its own | |
1738 | registers and execution stack, and perhaps private memory. | |
1739 | ||
1740 | @value{GDBN} provides these facilities for debugging multi-thread | |
1741 | programs: | |
1742 | ||
1743 | @itemize @bullet | |
1744 | @item automatic notification of new threads | |
1745 | @item @samp{thread @var{threadno}}, a command to switch among threads | |
1746 | @item @samp{info threads}, a command to inquire about existing threads | |
1747 | @item @samp{thread apply [@var{threadno}] [@var{all}] @var{args}}, | |
1748 | a command to apply a command to a list of threads | |
1749 | @item thread-specific breakpoints | |
1750 | @end itemize | |
1751 | ||
c906108c SS |
1752 | @quotation |
1753 | @emph{Warning:} These facilities are not yet available on every | |
1754 | @value{GDBN} configuration where the operating system supports threads. | |
1755 | If your @value{GDBN} does not support threads, these commands have no | |
1756 | effect. For example, a system without thread support shows no output | |
1757 | from @samp{info threads}, and always rejects the @code{thread} command, | |
1758 | like this: | |
1759 | ||
1760 | @smallexample | |
1761 | (@value{GDBP}) info threads | |
1762 | (@value{GDBP}) thread 1 | |
1763 | Thread ID 1 not known. Use the "info threads" command to | |
1764 | see the IDs of currently known threads. | |
1765 | @end smallexample | |
1766 | @c FIXME to implementors: how hard would it be to say "sorry, this GDB | |
1767 | @c doesn't support threads"? | |
1768 | @end quotation | |
c906108c SS |
1769 | |
1770 | @cindex focus of debugging | |
1771 | @cindex current thread | |
1772 | The @value{GDBN} thread debugging facility allows you to observe all | |
1773 | threads while your program runs---but whenever @value{GDBN} takes | |
1774 | control, one thread in particular is always the focus of debugging. | |
1775 | This thread is called the @dfn{current thread}. Debugging commands show | |
1776 | program information from the perspective of the current thread. | |
1777 | ||
c906108c SS |
1778 | @kindex New @var{systag} |
1779 | @cindex thread identifier (system) | |
1780 | @c FIXME-implementors!! It would be more helpful if the [New...] message | |
1781 | @c included GDB's numeric thread handle, so you could just go to that | |
1782 | @c thread without first checking `info threads'. | |
1783 | Whenever @value{GDBN} detects a new thread in your program, it displays | |
1784 | the target system's identification for the thread with a message in the | |
1785 | form @samp{[New @var{systag}]}. @var{systag} is a thread identifier | |
1786 | whose form varies depending on the particular system. For example, on | |
1787 | LynxOS, you might see | |
1788 | ||
1789 | @example | |
1790 | [New process 35 thread 27] | |
1791 | @end example | |
1792 | ||
1793 | @noindent | |
1794 | when @value{GDBN} notices a new thread. In contrast, on an SGI system, | |
1795 | the @var{systag} is simply something like @samp{process 368}, with no | |
1796 | further qualifier. | |
1797 | ||
1798 | @c FIXME!! (1) Does the [New...] message appear even for the very first | |
1799 | @c thread of a program, or does it only appear for the | |
1800 | @c second---i.e., when it becomes obvious we have a multithread | |
1801 | @c program? | |
1802 | @c (2) *Is* there necessarily a first thread always? Or do some | |
1803 | @c multithread systems permit starting a program with multiple | |
1804 | @c threads ab initio? | |
1805 | ||
1806 | @cindex thread number | |
1807 | @cindex thread identifier (GDB) | |
1808 | For debugging purposes, @value{GDBN} associates its own thread | |
1809 | number---always a single integer---with each thread in your program. | |
1810 | ||
1811 | @table @code | |
1812 | @kindex info threads | |
1813 | @item info threads | |
1814 | Display a summary of all threads currently in your | |
1815 | program. @value{GDBN} displays for each thread (in this order): | |
1816 | ||
1817 | @enumerate | |
1818 | @item the thread number assigned by @value{GDBN} | |
1819 | ||
1820 | @item the target system's thread identifier (@var{systag}) | |
1821 | ||
1822 | @item the current stack frame summary for that thread | |
1823 | @end enumerate | |
1824 | ||
1825 | @noindent | |
1826 | An asterisk @samp{*} to the left of the @value{GDBN} thread number | |
1827 | indicates the current thread. | |
1828 | ||
1829 | For example, | |
1830 | @end table | |
1831 | @c end table here to get a little more width for example | |
1832 | ||
1833 | @smallexample | |
1834 | (@value{GDBP}) info threads | |
1835 | 3 process 35 thread 27 0x34e5 in sigpause () | |
1836 | 2 process 35 thread 23 0x34e5 in sigpause () | |
1837 | * 1 process 35 thread 13 main (argc=1, argv=0x7ffffff8) | |
1838 | at threadtest.c:68 | |
1839 | @end smallexample | |
53a5351d JM |
1840 | |
1841 | On HP-UX systems: | |
c906108c SS |
1842 | |
1843 | @cindex thread number | |
1844 | @cindex thread identifier (GDB) | |
1845 | For debugging purposes, @value{GDBN} associates its own thread | |
1846 | number---a small integer assigned in thread-creation order---with each | |
1847 | thread in your program. | |
1848 | ||
1849 | @kindex New @var{systag} | |
1850 | @cindex thread identifier (system) | |
1851 | @c FIXME-implementors!! It would be more helpful if the [New...] message | |
1852 | @c included GDB's numeric thread handle, so you could just go to that | |
1853 | @c thread without first checking `info threads'. | |
1854 | Whenever @value{GDBN} detects a new thread in your program, it displays | |
1855 | both @value{GDBN}'s thread number and the target system's identification for the thread with a message in the | |
1856 | form @samp{[New @var{systag}]}. @var{systag} is a thread identifier | |
1857 | whose form varies depending on the particular system. For example, on | |
1858 | HP-UX, you see | |
1859 | ||
1860 | @example | |
1861 | [New thread 2 (system thread 26594)] | |
1862 | @end example | |
1863 | ||
1864 | @noindent | |
1865 | when @value{GDBN} notices a new thread. | |
1866 | ||
1867 | @table @code | |
1868 | @kindex info threads | |
1869 | @item info threads | |
1870 | Display a summary of all threads currently in your | |
1871 | program. @value{GDBN} displays for each thread (in this order): | |
1872 | ||
1873 | @enumerate | |
1874 | @item the thread number assigned by @value{GDBN} | |
1875 | ||
1876 | @item the target system's thread identifier (@var{systag}) | |
1877 | ||
1878 | @item the current stack frame summary for that thread | |
1879 | @end enumerate | |
1880 | ||
1881 | @noindent | |
1882 | An asterisk @samp{*} to the left of the @value{GDBN} thread number | |
1883 | indicates the current thread. | |
1884 | ||
1885 | For example, | |
1886 | @end table | |
1887 | @c end table here to get a little more width for example | |
1888 | ||
1889 | @example | |
1890 | (@value{GDBP}) info threads | |
1891 | * 3 system thread 26607 worker (wptr=0x7b09c318 "@@") at quicksort.c:137 | |
1892 | 2 system thread 26606 0x7b0030d8 in __ksleep () from /usr/lib/libc.2 | |
1893 | 1 system thread 27905 0x7b003498 in _brk () from /usr/lib/libc.2 | |
1894 | @end example | |
c906108c SS |
1895 | |
1896 | @table @code | |
1897 | @kindex thread @var{threadno} | |
1898 | @item thread @var{threadno} | |
1899 | Make thread number @var{threadno} the current thread. The command | |
1900 | argument @var{threadno} is the internal @value{GDBN} thread number, as | |
1901 | shown in the first field of the @samp{info threads} display. | |
1902 | @value{GDBN} responds by displaying the system identifier of the thread | |
1903 | you selected, and its current stack frame summary: | |
1904 | ||
1905 | @smallexample | |
1906 | @c FIXME!! This example made up; find a @value{GDBN} w/threads and get real one | |
1907 | (@value{GDBP}) thread 2 | |
c906108c | 1908 | [Switching to process 35 thread 23] |
c906108c SS |
1909 | 0x34e5 in sigpause () |
1910 | @end smallexample | |
1911 | ||
1912 | @noindent | |
1913 | As with the @samp{[New @dots{}]} message, the form of the text after | |
1914 | @samp{Switching to} depends on your system's conventions for identifying | |
1915 | threads. | |
1916 | ||
1917 | @kindex thread apply | |
1918 | @item thread apply [@var{threadno}] [@var{all}] @var{args} | |
1919 | The @code{thread apply} command allows you to apply a command to one or | |
1920 | more threads. Specify the numbers of the threads that you want affected | |
1921 | with the command argument @var{threadno}. @var{threadno} is the internal | |
1922 | @value{GDBN} thread number, as shown in the first field of the @samp{info | |
1923 | threads} display. To apply a command to all threads, use | |
1924 | @code{thread apply all} @var{args}. | |
1925 | @end table | |
1926 | ||
1927 | @cindex automatic thread selection | |
1928 | @cindex switching threads automatically | |
1929 | @cindex threads, automatic switching | |
1930 | Whenever @value{GDBN} stops your program, due to a breakpoint or a | |
1931 | signal, it automatically selects the thread where that breakpoint or | |
1932 | signal happened. @value{GDBN} alerts you to the context switch with a | |
1933 | message of the form @samp{[Switching to @var{systag}]} to identify the | |
1934 | thread. | |
1935 | ||
1936 | @xref{Thread Stops,,Stopping and starting multi-thread programs}, for | |
1937 | more information about how @value{GDBN} behaves when you stop and start | |
1938 | programs with multiple threads. | |
1939 | ||
1940 | @xref{Set Watchpoints,,Setting watchpoints}, for information about | |
1941 | watchpoints in programs with multiple threads. | |
c906108c | 1942 | |
53a5351d | 1943 | @node Processes |
c906108c SS |
1944 | @section Debugging programs with multiple processes |
1945 | ||
1946 | @cindex fork, debugging programs which call | |
1947 | @cindex multiple processes | |
1948 | @cindex processes, multiple | |
53a5351d JM |
1949 | On most systems, @value{GDBN} has no special support for debugging |
1950 | programs which create additional processes using the @code{fork} | |
1951 | function. When a program forks, @value{GDBN} will continue to debug the | |
1952 | parent process and the child process will run unimpeded. If you have | |
1953 | set a breakpoint in any code which the child then executes, the child | |
1954 | will get a @code{SIGTRAP} signal which (unless it catches the signal) | |
1955 | will cause it to terminate. | |
c906108c SS |
1956 | |
1957 | However, if you want to debug the child process there is a workaround | |
1958 | which isn't too painful. Put a call to @code{sleep} in the code which | |
1959 | the child process executes after the fork. It may be useful to sleep | |
1960 | only if a certain environment variable is set, or a certain file exists, | |
1961 | so that the delay need not occur when you don't want to run @value{GDBN} | |
1962 | on the child. While the child is sleeping, use the @code{ps} program to | |
1963 | get its process ID. Then tell @value{GDBN} (a new invocation of | |
1964 | @value{GDBN} if you are also debugging the parent process) to attach to | |
d4f3574e | 1965 | the child process (@pxref{Attach}). From that point on you can debug |
c906108c | 1966 | the child process just like any other process which you attached to. |
c906108c | 1967 | |
53a5351d JM |
1968 | On HP-UX (11.x and later only?), @value{GDBN} provides support for |
1969 | debugging programs that create additional processes using the | |
1970 | @code{fork} or @code{vfork} function. | |
c906108c SS |
1971 | |
1972 | By default, when a program forks, @value{GDBN} will continue to debug | |
1973 | the parent process and the child process will run unimpeded. | |
1974 | ||
1975 | If you want to follow the child process instead of the parent process, | |
1976 | use the command @w{@code{set follow-fork-mode}}. | |
1977 | ||
1978 | @table @code | |
1979 | @kindex set follow-fork-mode | |
1980 | @item set follow-fork-mode @var{mode} | |
1981 | Set the debugger response to a program call of @code{fork} or | |
1982 | @code{vfork}. A call to @code{fork} or @code{vfork} creates a new | |
1983 | process. The @var{mode} can be: | |
1984 | ||
1985 | @table @code | |
1986 | @item parent | |
1987 | The original process is debugged after a fork. The child process runs | |
2df3850c | 1988 | unimpeded. This is the default. |
c906108c SS |
1989 | |
1990 | @item child | |
1991 | The new process is debugged after a fork. The parent process runs | |
1992 | unimpeded. | |
1993 | ||
1994 | @item ask | |
1995 | The debugger will ask for one of the above choices. | |
1996 | @end table | |
1997 | ||
1998 | @item show follow-fork-mode | |
2df3850c | 1999 | Display the current debugger response to a @code{fork} or @code{vfork} call. |
c906108c SS |
2000 | @end table |
2001 | ||
2002 | If you ask to debug a child process and a @code{vfork} is followed by an | |
2003 | @code{exec}, @value{GDBN} executes the new target up to the first | |
2004 | breakpoint in the new target. If you have a breakpoint set on | |
2005 | @code{main} in your original program, the breakpoint will also be set on | |
2006 | the child process's @code{main}. | |
2007 | ||
2008 | When a child process is spawned by @code{vfork}, you cannot debug the | |
2009 | child or parent until an @code{exec} call completes. | |
2010 | ||
2011 | If you issue a @code{run} command to @value{GDBN} after an @code{exec} | |
2012 | call executes, the new target restarts. To restart the parent process, | |
2013 | use the @code{file} command with the parent executable name as its | |
2014 | argument. | |
2015 | ||
2016 | You can use the @code{catch} command to make @value{GDBN} stop whenever | |
2017 | a @code{fork}, @code{vfork}, or @code{exec} call is made. @xref{Set | |
2018 | Catchpoints, ,Setting catchpoints}. | |
c906108c | 2019 | |
53a5351d | 2020 | @node Stopping |
c906108c SS |
2021 | @chapter Stopping and Continuing |
2022 | ||
2023 | The principal purposes of using a debugger are so that you can stop your | |
2024 | program before it terminates; or so that, if your program runs into | |
2025 | trouble, you can investigate and find out why. | |
2026 | ||
7a292a7a SS |
2027 | Inside @value{GDBN}, your program may stop for any of several reasons, |
2028 | such as a signal, a breakpoint, or reaching a new line after a | |
2029 | @value{GDBN} command such as @code{step}. You may then examine and | |
2030 | change variables, set new breakpoints or remove old ones, and then | |
2031 | continue execution. Usually, the messages shown by @value{GDBN} provide | |
2032 | ample explanation of the status of your program---but you can also | |
2033 | explicitly request this information at any time. | |
c906108c SS |
2034 | |
2035 | @table @code | |
2036 | @kindex info program | |
2037 | @item info program | |
2038 | Display information about the status of your program: whether it is | |
7a292a7a | 2039 | running or not, what process it is, and why it stopped. |
c906108c SS |
2040 | @end table |
2041 | ||
2042 | @menu | |
2043 | * Breakpoints:: Breakpoints, watchpoints, and catchpoints | |
2044 | * Continuing and Stepping:: Resuming execution | |
c906108c | 2045 | * Signals:: Signals |
c906108c | 2046 | * Thread Stops:: Stopping and starting multi-thread programs |
c906108c SS |
2047 | @end menu |
2048 | ||
53a5351d | 2049 | @node Breakpoints |
c906108c SS |
2050 | @section Breakpoints, watchpoints, and catchpoints |
2051 | ||
2052 | @cindex breakpoints | |
2053 | A @dfn{breakpoint} makes your program stop whenever a certain point in | |
2054 | the program is reached. For each breakpoint, you can add conditions to | |
2055 | control in finer detail whether your program stops. You can set | |
2056 | breakpoints with the @code{break} command and its variants (@pxref{Set | |
2057 | Breaks, ,Setting breakpoints}), to specify the place where your program | |
2058 | should stop by line number, function name or exact address in the | |
2059 | program. | |
2060 | ||
2061 | In HP-UX, SunOS 4.x, SVR4, and Alpha OSF/1 configurations, you can set | |
2062 | breakpoints in shared libraries before the executable is run. There is | |
2063 | a minor limitation on HP-UX systems: you must wait until the executable | |
2064 | is run in order to set breakpoints in shared library routines that are | |
2065 | not called directly by the program (for example, routines that are | |
2066 | arguments in a @code{pthread_create} call). | |
2067 | ||
2068 | @cindex watchpoints | |
2069 | @cindex memory tracing | |
2070 | @cindex breakpoint on memory address | |
2071 | @cindex breakpoint on variable modification | |
2072 | A @dfn{watchpoint} is a special breakpoint that stops your program | |
2073 | when the value of an expression changes. You must use a different | |
2074 | command to set watchpoints (@pxref{Set Watchpoints, ,Setting | |
2075 | watchpoints}), but aside from that, you can manage a watchpoint like | |
2076 | any other breakpoint: you enable, disable, and delete both breakpoints | |
2077 | and watchpoints using the same commands. | |
2078 | ||
2079 | You can arrange to have values from your program displayed automatically | |
2080 | whenever @value{GDBN} stops at a breakpoint. @xref{Auto Display,, | |
2081 | Automatic display}. | |
2082 | ||
2083 | @cindex catchpoints | |
2084 | @cindex breakpoint on events | |
2085 | A @dfn{catchpoint} is another special breakpoint that stops your program | |
2086 | when a certain kind of event occurs, such as the throwing of a C++ | |
2087 | exception or the loading of a library. As with watchpoints, you use a | |
2088 | different command to set a catchpoint (@pxref{Set Catchpoints, ,Setting | |
2089 | catchpoints}), but aside from that, you can manage a catchpoint like any | |
2090 | other breakpoint. (To stop when your program receives a signal, use the | |
d4f3574e | 2091 | @code{handle} command; see @ref{Signals, ,Signals}.) |
c906108c SS |
2092 | |
2093 | @cindex breakpoint numbers | |
2094 | @cindex numbers for breakpoints | |
2095 | @value{GDBN} assigns a number to each breakpoint, watchpoint, or | |
2096 | catchpoint when you create it; these numbers are successive integers | |
2097 | starting with one. In many of the commands for controlling various | |
2098 | features of breakpoints you use the breakpoint number to say which | |
2099 | breakpoint you want to change. Each breakpoint may be @dfn{enabled} or | |
2100 | @dfn{disabled}; if disabled, it has no effect on your program until you | |
2101 | enable it again. | |
2102 | ||
c5394b80 JM |
2103 | @cindex breakpoint ranges |
2104 | @cindex ranges of breakpoints | |
2105 | Some @value{GDBN} commands accept a range of breakpoints on which to | |
2106 | operate. A breakpoint range is either a single breakpoint number, like | |
2107 | @samp{5}, or two such numbers, in increasing order, separated by a | |
2108 | hyphen, like @samp{5-7}. When a breakpoint range is given to a command, | |
2109 | all breakpoint in that range are operated on. | |
2110 | ||
c906108c SS |
2111 | @menu |
2112 | * Set Breaks:: Setting breakpoints | |
2113 | * Set Watchpoints:: Setting watchpoints | |
2114 | * Set Catchpoints:: Setting catchpoints | |
2115 | * Delete Breaks:: Deleting breakpoints | |
2116 | * Disabling:: Disabling breakpoints | |
2117 | * Conditions:: Break conditions | |
2118 | * Break Commands:: Breakpoint command lists | |
c906108c | 2119 | * Breakpoint Menus:: Breakpoint menus |
d4f3574e | 2120 | * Error in Breakpoints:: ``Cannot insert breakpoints'' |
c906108c SS |
2121 | @end menu |
2122 | ||
53a5351d | 2123 | @node Set Breaks |
c906108c SS |
2124 | @subsection Setting breakpoints |
2125 | ||
2126 | @c FIXME LMB what does GDB do if no code on line of breakpt? | |
2127 | @c consider in particular declaration with/without initialization. | |
2128 | @c | |
2129 | @c FIXME 2 is there stuff on this already? break at fun start, already init? | |
2130 | ||
2131 | @kindex break | |
2132 | @kindex b | |
2133 | @kindex $bpnum | |
2134 | @cindex latest breakpoint | |
2135 | Breakpoints are set with the @code{break} command (abbreviated | |
2136 | @code{b}). The debugger convenience variable @samp{$bpnum} records the | |
2137 | number of the breakpoints you've set most recently; see @ref{Convenience | |
2138 | Vars,, Convenience variables}, for a discussion of what you can do with | |
2139 | convenience variables. | |
2140 | ||
2141 | You have several ways to say where the breakpoint should go. | |
2142 | ||
2143 | @table @code | |
2144 | @item break @var{function} | |
2145 | Set a breakpoint at entry to function @var{function}. | |
c906108c SS |
2146 | When using source languages that permit overloading of symbols, such as |
2147 | C++, @var{function} may refer to more than one possible place to break. | |
2148 | @xref{Breakpoint Menus,,Breakpoint menus}, for a discussion of that situation. | |
c906108c SS |
2149 | |
2150 | @item break +@var{offset} | |
2151 | @itemx break -@var{offset} | |
2152 | Set a breakpoint some number of lines forward or back from the position | |
d4f3574e | 2153 | at which execution stopped in the currently selected @dfn{stack frame}. |
2df3850c | 2154 | (@xref{Frames, ,Frames}, for a description of stack frames.) |
c906108c SS |
2155 | |
2156 | @item break @var{linenum} | |
2157 | Set a breakpoint at line @var{linenum} in the current source file. | |
d4f3574e SS |
2158 | The current source file is the last file whose source text was printed. |
2159 | The breakpoint will stop your program just before it executes any of the | |
c906108c SS |
2160 | code on that line. |
2161 | ||
2162 | @item break @var{filename}:@var{linenum} | |
2163 | Set a breakpoint at line @var{linenum} in source file @var{filename}. | |
2164 | ||
2165 | @item break @var{filename}:@var{function} | |
2166 | Set a breakpoint at entry to function @var{function} found in file | |
2167 | @var{filename}. Specifying a file name as well as a function name is | |
2168 | superfluous except when multiple files contain similarly named | |
2169 | functions. | |
2170 | ||
2171 | @item break *@var{address} | |
2172 | Set a breakpoint at address @var{address}. You can use this to set | |
2173 | breakpoints in parts of your program which do not have debugging | |
2174 | information or source files. | |
2175 | ||
2176 | @item break | |
2177 | When called without any arguments, @code{break} sets a breakpoint at | |
2178 | the next instruction to be executed in the selected stack frame | |
2179 | (@pxref{Stack, ,Examining the Stack}). In any selected frame but the | |
2180 | innermost, this makes your program stop as soon as control | |
2181 | returns to that frame. This is similar to the effect of a | |
2182 | @code{finish} command in the frame inside the selected frame---except | |
2183 | that @code{finish} does not leave an active breakpoint. If you use | |
2184 | @code{break} without an argument in the innermost frame, @value{GDBN} stops | |
2185 | the next time it reaches the current location; this may be useful | |
2186 | inside loops. | |
2187 | ||
2188 | @value{GDBN} normally ignores breakpoints when it resumes execution, until at | |
2189 | least one instruction has been executed. If it did not do this, you | |
2190 | would be unable to proceed past a breakpoint without first disabling the | |
2191 | breakpoint. This rule applies whether or not the breakpoint already | |
2192 | existed when your program stopped. | |
2193 | ||
2194 | @item break @dots{} if @var{cond} | |
2195 | Set a breakpoint with condition @var{cond}; evaluate the expression | |
2196 | @var{cond} each time the breakpoint is reached, and stop only if the | |
2197 | value is nonzero---that is, if @var{cond} evaluates as true. | |
2198 | @samp{@dots{}} stands for one of the possible arguments described | |
2199 | above (or no argument) specifying where to break. @xref{Conditions, | |
2200 | ,Break conditions}, for more information on breakpoint conditions. | |
2201 | ||
2202 | @kindex tbreak | |
2203 | @item tbreak @var{args} | |
2204 | Set a breakpoint enabled only for one stop. @var{args} are the | |
2205 | same as for the @code{break} command, and the breakpoint is set in the same | |
2206 | way, but the breakpoint is automatically deleted after the first time your | |
2207 | program stops there. @xref{Disabling, ,Disabling breakpoints}. | |
2208 | ||
c906108c SS |
2209 | @kindex hbreak |
2210 | @item hbreak @var{args} | |
d4f3574e SS |
2211 | Set a hardware-assisted breakpoint. @var{args} are the same as for the |
2212 | @code{break} command and the breakpoint is set in the same way, but the | |
c906108c SS |
2213 | breakpoint requires hardware support and some target hardware may not |
2214 | have this support. The main purpose of this is EPROM/ROM code | |
d4f3574e SS |
2215 | debugging, so you can set a breakpoint at an instruction without |
2216 | changing the instruction. This can be used with the new trap-generation | |
2217 | provided by SPARClite DSU and some x86-based targets. These targets | |
2218 | will generate traps when a program accesses some data or instruction | |
2219 | address that is assigned to the debug registers. However the hardware | |
2220 | breakpoint registers can take a limited number of breakpoints. For | |
2221 | example, on the DSU, only two data breakpoints can be set at a time, and | |
2222 | @value{GDBN} will reject this command if more than two are used. Delete | |
2223 | or disable unused hardware breakpoints before setting new ones | |
2224 | (@pxref{Disabling, ,Disabling}). @xref{Conditions, ,Break conditions}. | |
c906108c SS |
2225 | |
2226 | @kindex thbreak | |
2227 | @item thbreak @var{args} | |
2228 | Set a hardware-assisted breakpoint enabled only for one stop. @var{args} | |
2229 | are the same as for the @code{hbreak} command and the breakpoint is set in | |
2230 | the same way. However, like the @code{tbreak} command, | |
2231 | the breakpoint is automatically deleted after the | |
2232 | first time your program stops there. Also, like the @code{hbreak} | |
2233 | command, the breakpoint requires hardware support and some target hardware | |
2234 | may not have this support. @xref{Disabling, ,Disabling breakpoints}. | |
d4f3574e | 2235 | See also @ref{Conditions, ,Break conditions}. |
c906108c SS |
2236 | |
2237 | @kindex rbreak | |
2238 | @cindex regular expression | |
2239 | @item rbreak @var{regex} | |
c906108c | 2240 | Set breakpoints on all functions matching the regular expression |
11cf8741 JM |
2241 | @var{regex}. This command sets an unconditional breakpoint on all |
2242 | matches, printing a list of all breakpoints it set. Once these | |
2243 | breakpoints are set, they are treated just like the breakpoints set with | |
2244 | the @code{break} command. You can delete them, disable them, or make | |
2245 | them conditional the same way as any other breakpoint. | |
2246 | ||
2247 | The syntax of the regular expression is the standard one used with tools | |
2248 | like @file{grep}. Note that this is different from the syntax used by | |
2249 | shells, so for instance @code{foo*} matches all functions that include | |
2250 | an @code{fo} followed by zero or more @code{o}s. There is an implicit | |
2251 | @code{.*} leading and trailing the regular expression you supply, so to | |
2252 | match only functions that begin with @code{foo}, use @code{^foo}. | |
c906108c | 2253 | |
c906108c SS |
2254 | When debugging C++ programs, @code{rbreak} is useful for setting |
2255 | breakpoints on overloaded functions that are not members of any special | |
2256 | classes. | |
c906108c SS |
2257 | |
2258 | @kindex info breakpoints | |
2259 | @cindex @code{$_} and @code{info breakpoints} | |
2260 | @item info breakpoints @r{[}@var{n}@r{]} | |
2261 | @itemx info break @r{[}@var{n}@r{]} | |
2262 | @itemx info watchpoints @r{[}@var{n}@r{]} | |
2263 | Print a table of all breakpoints, watchpoints, and catchpoints set and | |
2264 | not deleted, with the following columns for each breakpoint: | |
2265 | ||
2266 | @table @emph | |
2267 | @item Breakpoint Numbers | |
2268 | @item Type | |
2269 | Breakpoint, watchpoint, or catchpoint. | |
2270 | @item Disposition | |
2271 | Whether the breakpoint is marked to be disabled or deleted when hit. | |
2272 | @item Enabled or Disabled | |
2273 | Enabled breakpoints are marked with @samp{y}. @samp{n} marks breakpoints | |
2274 | that are not enabled. | |
2275 | @item Address | |
2df3850c | 2276 | Where the breakpoint is in your program, as a memory address. |
c906108c SS |
2277 | @item What |
2278 | Where the breakpoint is in the source for your program, as a file and | |
2279 | line number. | |
2280 | @end table | |
2281 | ||
2282 | @noindent | |
2283 | If a breakpoint is conditional, @code{info break} shows the condition on | |
2284 | the line following the affected breakpoint; breakpoint commands, if any, | |
2285 | are listed after that. | |
2286 | ||
2287 | @noindent | |
2288 | @code{info break} with a breakpoint | |
2289 | number @var{n} as argument lists only that breakpoint. The | |
2290 | convenience variable @code{$_} and the default examining-address for | |
2291 | the @code{x} command are set to the address of the last breakpoint | |
2292 | listed (@pxref{Memory, ,Examining memory}). | |
2293 | ||
2294 | @noindent | |
2295 | @code{info break} displays a count of the number of times the breakpoint | |
2296 | has been hit. This is especially useful in conjunction with the | |
2297 | @code{ignore} command. You can ignore a large number of breakpoint | |
2298 | hits, look at the breakpoint info to see how many times the breakpoint | |
2299 | was hit, and then run again, ignoring one less than that number. This | |
2300 | will get you quickly to the last hit of that breakpoint. | |
2301 | @end table | |
2302 | ||
2303 | @value{GDBN} allows you to set any number of breakpoints at the same place in | |
2304 | your program. There is nothing silly or meaningless about this. When | |
2305 | the breakpoints are conditional, this is even useful | |
2306 | (@pxref{Conditions, ,Break conditions}). | |
2307 | ||
2308 | @cindex negative breakpoint numbers | |
2309 | @cindex internal @value{GDBN} breakpoints | |
2310 | @value{GDBN} itself sometimes sets breakpoints in your program for special | |
2311 | purposes, such as proper handling of @code{longjmp} (in C programs). | |
2312 | These internal breakpoints are assigned negative numbers, starting with | |
2313 | @code{-1}; @samp{info breakpoints} does not display them. | |
2314 | ||
2315 | You can see these breakpoints with the @value{GDBN} maintenance command | |
2316 | @samp{maint info breakpoints}. | |
2317 | ||
2318 | @table @code | |
2319 | @kindex maint info breakpoints | |
2320 | @item maint info breakpoints | |
2321 | Using the same format as @samp{info breakpoints}, display both the | |
2322 | breakpoints you've set explicitly, and those @value{GDBN} is using for | |
2323 | internal purposes. Internal breakpoints are shown with negative | |
2324 | breakpoint numbers. The type column identifies what kind of breakpoint | |
2325 | is shown: | |
2326 | ||
2327 | @table @code | |
2328 | @item breakpoint | |
2329 | Normal, explicitly set breakpoint. | |
2330 | ||
2331 | @item watchpoint | |
2332 | Normal, explicitly set watchpoint. | |
2333 | ||
2334 | @item longjmp | |
2335 | Internal breakpoint, used to handle correctly stepping through | |
2336 | @code{longjmp} calls. | |
2337 | ||
2338 | @item longjmp resume | |
2339 | Internal breakpoint at the target of a @code{longjmp}. | |
2340 | ||
2341 | @item until | |
2342 | Temporary internal breakpoint used by the @value{GDBN} @code{until} command. | |
2343 | ||
2344 | @item finish | |
2345 | Temporary internal breakpoint used by the @value{GDBN} @code{finish} command. | |
2346 | ||
c906108c SS |
2347 | @item shlib events |
2348 | Shared library events. | |
53a5351d | 2349 | |
c906108c | 2350 | @end table |
53a5351d | 2351 | |
c906108c SS |
2352 | @end table |
2353 | ||
2354 | ||
53a5351d | 2355 | @node Set Watchpoints |
c906108c SS |
2356 | @subsection Setting watchpoints |
2357 | ||
2358 | @cindex setting watchpoints | |
2359 | @cindex software watchpoints | |
2360 | @cindex hardware watchpoints | |
2361 | You can use a watchpoint to stop execution whenever the value of an | |
2362 | expression changes, without having to predict a particular place where | |
2363 | this may happen. | |
2364 | ||
2365 | Depending on your system, watchpoints may be implemented in software or | |
2df3850c | 2366 | hardware. @value{GDBN} does software watchpointing by single-stepping your |
c906108c SS |
2367 | program and testing the variable's value each time, which is hundreds of |
2368 | times slower than normal execution. (But this may still be worth it, to | |
2369 | catch errors where you have no clue what part of your program is the | |
2370 | culprit.) | |
2371 | ||
d4f3574e | 2372 | On some systems, such as HP-UX, Linux and some other x86-based targets, |
2df3850c | 2373 | @value{GDBN} includes support for |
c906108c SS |
2374 | hardware watchpoints, which do not slow down the running of your |
2375 | program. | |
2376 | ||
2377 | @table @code | |
2378 | @kindex watch | |
2379 | @item watch @var{expr} | |
2380 | Set a watchpoint for an expression. @value{GDBN} will break when @var{expr} | |
2381 | is written into by the program and its value changes. | |
2382 | ||
2383 | @kindex rwatch | |
2384 | @item rwatch @var{expr} | |
2385 | Set a watchpoint that will break when watch @var{expr} is read by the program. | |
c906108c SS |
2386 | |
2387 | @kindex awatch | |
2388 | @item awatch @var{expr} | |
2df3850c | 2389 | Set a watchpoint that will break when @var{expr} is either read or written into |
7be570e7 | 2390 | by the program. |
c906108c SS |
2391 | |
2392 | @kindex info watchpoints | |
2393 | @item info watchpoints | |
2394 | This command prints a list of watchpoints, breakpoints, and catchpoints; | |
2395 | it is the same as @code{info break}. | |
2396 | @end table | |
2397 | ||
2398 | @value{GDBN} sets a @dfn{hardware watchpoint} if possible. Hardware | |
2399 | watchpoints execute very quickly, and the debugger reports a change in | |
2400 | value at the exact instruction where the change occurs. If @value{GDBN} | |
2401 | cannot set a hardware watchpoint, it sets a software watchpoint, which | |
2402 | executes more slowly and reports the change in value at the next | |
2403 | statement, not the instruction, after the change occurs. | |
2404 | ||
2405 | When you issue the @code{watch} command, @value{GDBN} reports | |
2406 | ||
2407 | @example | |
2408 | Hardware watchpoint @var{num}: @var{expr} | |
2409 | @end example | |
2410 | ||
2411 | @noindent | |
2412 | if it was able to set a hardware watchpoint. | |
2413 | ||
7be570e7 JM |
2414 | Currently, the @code{awatch} and @code{rwatch} commands can only set |
2415 | hardware watchpoints, because accesses to data that don't change the | |
2416 | value of the watched expression cannot be detected without examining | |
2417 | every instruction as it is being executed, and @value{GDBN} does not do | |
2418 | that currently. If @value{GDBN} finds that it is unable to set a | |
2419 | hardware breakpoint with the @code{awatch} or @code{rwatch} command, it | |
2420 | will print a message like this: | |
2421 | ||
2422 | @smallexample | |
2423 | Expression cannot be implemented with read/access watchpoint. | |
2424 | @end smallexample | |
2425 | ||
2426 | Sometimes, @value{GDBN} cannot set a hardware watchpoint because the | |
2427 | data type of the watched expression is wider than what a hardware | |
2428 | watchpoint on the target machine can handle. For example, some systems | |
2429 | can only watch regions that are up to 4 bytes wide; on such systems you | |
2430 | cannot set hardware watchpoints for an expression that yields a | |
2431 | double-precision floating-point number (which is typically 8 bytes | |
2432 | wide). As a work-around, it might be possible to break the large region | |
2433 | into a series of smaller ones and watch them with separate watchpoints. | |
2434 | ||
2435 | If you set too many hardware watchpoints, @value{GDBN} might be unable | |
2436 | to insert all of them when you resume the execution of your program. | |
2437 | Since the precise number of active watchpoints is unknown until such | |
2438 | time as the program is about to be resumed, @value{GDBN} might not be | |
2439 | able to warn you about this when you set the watchpoints, and the | |
2440 | warning will be printed only when the program is resumed: | |
2441 | ||
2442 | @smallexample | |
2443 | Hardware watchpoint @var{num}: Could not insert watchpoint | |
2444 | @end smallexample | |
2445 | ||
2446 | @noindent | |
2447 | If this happens, delete or disable some of the watchpoints. | |
2448 | ||
2449 | The SPARClite DSU will generate traps when a program accesses some data | |
2450 | or instruction address that is assigned to the debug registers. For the | |
2451 | data addresses, DSU facilitates the @code{watch} command. However the | |
2452 | hardware breakpoint registers can only take two data watchpoints, and | |
2453 | both watchpoints must be the same kind. For example, you can set two | |
2454 | watchpoints with @code{watch} commands, two with @code{rwatch} commands, | |
2455 | @strong{or} two with @code{awatch} commands, but you cannot set one | |
2456 | watchpoint with one command and the other with a different command. | |
c906108c SS |
2457 | @value{GDBN} will reject the command if you try to mix watchpoints. |
2458 | Delete or disable unused watchpoint commands before setting new ones. | |
2459 | ||
2460 | If you call a function interactively using @code{print} or @code{call}, | |
2df3850c | 2461 | any watchpoints you have set will be inactive until @value{GDBN} reaches another |
c906108c SS |
2462 | kind of breakpoint or the call completes. |
2463 | ||
7be570e7 JM |
2464 | @value{GDBN} automatically deletes watchpoints that watch local |
2465 | (automatic) variables, or expressions that involve such variables, when | |
2466 | they go out of scope, that is, when the execution leaves the block in | |
2467 | which these variables were defined. In particular, when the program | |
2468 | being debugged terminates, @emph{all} local variables go out of scope, | |
2469 | and so only watchpoints that watch global variables remain set. If you | |
2470 | rerun the program, you will need to set all such watchpoints again. One | |
2471 | way of doing that would be to set a code breakpoint at the entry to the | |
2472 | @code{main} function and when it breaks, set all the watchpoints. | |
2473 | ||
c906108c SS |
2474 | @quotation |
2475 | @cindex watchpoints and threads | |
2476 | @cindex threads and watchpoints | |
c906108c SS |
2477 | @emph{Warning:} In multi-thread programs, watchpoints have only limited |
2478 | usefulness. With the current watchpoint implementation, @value{GDBN} | |
2479 | can only watch the value of an expression @emph{in a single thread}. If | |
2480 | you are confident that the expression can only change due to the current | |
2481 | thread's activity (and if you are also confident that no other thread | |
2482 | can become current), then you can use watchpoints as usual. However, | |
2483 | @value{GDBN} may not notice when a non-current thread's activity changes | |
2484 | the expression. | |
53a5351d | 2485 | |
d4f3574e | 2486 | @c FIXME: this is almost identical to the previous paragraph. |
53a5351d JM |
2487 | @emph{HP-UX Warning:} In multi-thread programs, software watchpoints |
2488 | have only limited usefulness. If @value{GDBN} creates a software | |
2489 | watchpoint, it can only watch the value of an expression @emph{in a | |
2490 | single thread}. If you are confident that the expression can only | |
2491 | change due to the current thread's activity (and if you are also | |
2492 | confident that no other thread can become current), then you can use | |
2493 | software watchpoints as usual. However, @value{GDBN} may not notice | |
2494 | when a non-current thread's activity changes the expression. (Hardware | |
2495 | watchpoints, in contrast, watch an expression in all threads.) | |
c906108c | 2496 | @end quotation |
c906108c | 2497 | |
53a5351d | 2498 | @node Set Catchpoints |
c906108c | 2499 | @subsection Setting catchpoints |
d4f3574e | 2500 | @cindex catchpoints, setting |
c906108c SS |
2501 | @cindex exception handlers |
2502 | @cindex event handling | |
2503 | ||
2504 | You can use @dfn{catchpoints} to cause the debugger to stop for certain | |
2505 | kinds of program events, such as C++ exceptions or the loading of a | |
2506 | shared library. Use the @code{catch} command to set a catchpoint. | |
2507 | ||
2508 | @table @code | |
2509 | @kindex catch | |
2510 | @item catch @var{event} | |
2511 | Stop when @var{event} occurs. @var{event} can be any of the following: | |
2512 | @table @code | |
2513 | @item throw | |
2514 | @kindex catch throw | |
2515 | The throwing of a C++ exception. | |
2516 | ||
2517 | @item catch | |
2518 | @kindex catch catch | |
2519 | The catching of a C++ exception. | |
2520 | ||
2521 | @item exec | |
2522 | @kindex catch exec | |
2523 | A call to @code{exec}. This is currently only available for HP-UX. | |
2524 | ||
2525 | @item fork | |
2526 | @kindex catch fork | |
2527 | A call to @code{fork}. This is currently only available for HP-UX. | |
2528 | ||
2529 | @item vfork | |
2530 | @kindex catch vfork | |
2531 | A call to @code{vfork}. This is currently only available for HP-UX. | |
2532 | ||
2533 | @item load | |
2534 | @itemx load @var{libname} | |
2535 | @kindex catch load | |
2536 | The dynamic loading of any shared library, or the loading of the library | |
2537 | @var{libname}. This is currently only available for HP-UX. | |
2538 | ||
2539 | @item unload | |
2540 | @itemx unload @var{libname} | |
2541 | @kindex catch unload | |
2542 | The unloading of any dynamically loaded shared library, or the unloading | |
2543 | of the library @var{libname}. This is currently only available for HP-UX. | |
2544 | @end table | |
2545 | ||
2546 | @item tcatch @var{event} | |
2547 | Set a catchpoint that is enabled only for one stop. The catchpoint is | |
2548 | automatically deleted after the first time the event is caught. | |
2549 | ||
2550 | @end table | |
2551 | ||
2552 | Use the @code{info break} command to list the current catchpoints. | |
2553 | ||
2554 | There are currently some limitations to C++ exception handling | |
2555 | (@code{catch throw} and @code{catch catch}) in @value{GDBN}: | |
2556 | ||
2557 | @itemize @bullet | |
2558 | @item | |
2559 | If you call a function interactively, @value{GDBN} normally returns | |
2560 | control to you when the function has finished executing. If the call | |
2561 | raises an exception, however, the call may bypass the mechanism that | |
2562 | returns control to you and cause your program either to abort or to | |
2563 | simply continue running until it hits a breakpoint, catches a signal | |
2564 | that @value{GDBN} is listening for, or exits. This is the case even if | |
2565 | you set a catchpoint for the exception; catchpoints on exceptions are | |
2566 | disabled within interactive calls. | |
2567 | ||
2568 | @item | |
2569 | You cannot raise an exception interactively. | |
2570 | ||
2571 | @item | |
2572 | You cannot install an exception handler interactively. | |
2573 | @end itemize | |
2574 | ||
2575 | @cindex raise exceptions | |
2576 | Sometimes @code{catch} is not the best way to debug exception handling: | |
2577 | if you need to know exactly where an exception is raised, it is better to | |
2578 | stop @emph{before} the exception handler is called, since that way you | |
2579 | can see the stack before any unwinding takes place. If you set a | |
2580 | breakpoint in an exception handler instead, it may not be easy to find | |
2581 | out where the exception was raised. | |
2582 | ||
2583 | To stop just before an exception handler is called, you need some | |
2584 | knowledge of the implementation. In the case of @sc{gnu} C++, exceptions are | |
2585 | raised by calling a library function named @code{__raise_exception} | |
2586 | which has the following ANSI C interface: | |
2587 | ||
2588 | @example | |
2589 | /* @var{addr} is where the exception identifier is stored. | |
d4f3574e SS |
2590 | @var{id} is the exception identifier. */ |
2591 | void __raise_exception (void **addr, void *id); | |
c906108c SS |
2592 | @end example |
2593 | ||
2594 | @noindent | |
2595 | To make the debugger catch all exceptions before any stack | |
2596 | unwinding takes place, set a breakpoint on @code{__raise_exception} | |
2597 | (@pxref{Breakpoints, ,Breakpoints; watchpoints; and exceptions}). | |
2598 | ||
2599 | With a conditional breakpoint (@pxref{Conditions, ,Break conditions}) | |
2600 | that depends on the value of @var{id}, you can stop your program when | |
2601 | a specific exception is raised. You can use multiple conditional | |
2602 | breakpoints to stop your program when any of a number of exceptions are | |
2603 | raised. | |
2604 | ||
2605 | ||
53a5351d | 2606 | @node Delete Breaks |
c906108c SS |
2607 | @subsection Deleting breakpoints |
2608 | ||
2609 | @cindex clearing breakpoints, watchpoints, catchpoints | |
2610 | @cindex deleting breakpoints, watchpoints, catchpoints | |
2611 | It is often necessary to eliminate a breakpoint, watchpoint, or | |
2612 | catchpoint once it has done its job and you no longer want your program | |
2613 | to stop there. This is called @dfn{deleting} the breakpoint. A | |
2614 | breakpoint that has been deleted no longer exists; it is forgotten. | |
2615 | ||
2616 | With the @code{clear} command you can delete breakpoints according to | |
2617 | where they are in your program. With the @code{delete} command you can | |
2618 | delete individual breakpoints, watchpoints, or catchpoints by specifying | |
2619 | their breakpoint numbers. | |
2620 | ||
2621 | It is not necessary to delete a breakpoint to proceed past it. @value{GDBN} | |
2622 | automatically ignores breakpoints on the first instruction to be executed | |
2623 | when you continue execution without changing the execution address. | |
2624 | ||
2625 | @table @code | |
2626 | @kindex clear | |
2627 | @item clear | |
2628 | Delete any breakpoints at the next instruction to be executed in the | |
2629 | selected stack frame (@pxref{Selection, ,Selecting a frame}). When | |
2630 | the innermost frame is selected, this is a good way to delete a | |
2631 | breakpoint where your program just stopped. | |
2632 | ||
2633 | @item clear @var{function} | |
2634 | @itemx clear @var{filename}:@var{function} | |
2635 | Delete any breakpoints set at entry to the function @var{function}. | |
2636 | ||
2637 | @item clear @var{linenum} | |
2638 | @itemx clear @var{filename}:@var{linenum} | |
2639 | Delete any breakpoints set at or within the code of the specified line. | |
2640 | ||
2641 | @cindex delete breakpoints | |
2642 | @kindex delete | |
2643 | @kindex d | |
c5394b80 JM |
2644 | @item delete @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
2645 | Delete the breakpoints, watchpoints, or catchpoints of the breakpoint | |
2646 | ranges specified as arguments. If no argument is specified, delete all | |
c906108c SS |
2647 | breakpoints (@value{GDBN} asks confirmation, unless you have @code{set |
2648 | confirm off}). You can abbreviate this command as @code{d}. | |
2649 | @end table | |
2650 | ||
53a5351d | 2651 | @node Disabling |
c906108c SS |
2652 | @subsection Disabling breakpoints |
2653 | ||
2654 | @kindex disable breakpoints | |
2655 | @kindex enable breakpoints | |
2656 | Rather than deleting a breakpoint, watchpoint, or catchpoint, you might | |
2657 | prefer to @dfn{disable} it. This makes the breakpoint inoperative as if | |
2658 | it had been deleted, but remembers the information on the breakpoint so | |
2659 | that you can @dfn{enable} it again later. | |
2660 | ||
2661 | You disable and enable breakpoints, watchpoints, and catchpoints with | |
2662 | the @code{enable} and @code{disable} commands, optionally specifying one | |
2663 | or more breakpoint numbers as arguments. Use @code{info break} or | |
2664 | @code{info watch} to print a list of breakpoints, watchpoints, and | |
2665 | catchpoints if you do not know which numbers to use. | |
2666 | ||
2667 | A breakpoint, watchpoint, or catchpoint can have any of four different | |
2668 | states of enablement: | |
2669 | ||
2670 | @itemize @bullet | |
2671 | @item | |
2672 | Enabled. The breakpoint stops your program. A breakpoint set | |
2673 | with the @code{break} command starts out in this state. | |
2674 | @item | |
2675 | Disabled. The breakpoint has no effect on your program. | |
2676 | @item | |
2677 | Enabled once. The breakpoint stops your program, but then becomes | |
d4f3574e | 2678 | disabled. |
c906108c SS |
2679 | @item |
2680 | Enabled for deletion. The breakpoint stops your program, but | |
d4f3574e SS |
2681 | immediately after it does so it is deleted permanently. A breakpoint |
2682 | set with the @code{tbreak} command starts out in this state. | |
c906108c SS |
2683 | @end itemize |
2684 | ||
2685 | You can use the following commands to enable or disable breakpoints, | |
2686 | watchpoints, and catchpoints: | |
2687 | ||
2688 | @table @code | |
2689 | @kindex disable breakpoints | |
2690 | @kindex disable | |
2691 | @kindex dis | |
c5394b80 | 2692 | @item disable @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
c906108c SS |
2693 | Disable the specified breakpoints---or all breakpoints, if none are |
2694 | listed. A disabled breakpoint has no effect but is not forgotten. All | |
2695 | options such as ignore-counts, conditions and commands are remembered in | |
2696 | case the breakpoint is enabled again later. You may abbreviate | |
2697 | @code{disable} as @code{dis}. | |
2698 | ||
2699 | @kindex enable breakpoints | |
2700 | @kindex enable | |
c5394b80 | 2701 | @item enable @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
c906108c SS |
2702 | Enable the specified breakpoints (or all defined breakpoints). They |
2703 | become effective once again in stopping your program. | |
2704 | ||
c5394b80 | 2705 | @item enable @r{[}breakpoints@r{]} once @var{range}@dots{} |
c906108c SS |
2706 | Enable the specified breakpoints temporarily. @value{GDBN} disables any |
2707 | of these breakpoints immediately after stopping your program. | |
2708 | ||
c5394b80 | 2709 | @item enable @r{[}breakpoints@r{]} delete @var{range}@dots{} |
c906108c SS |
2710 | Enable the specified breakpoints to work once, then die. @value{GDBN} |
2711 | deletes any of these breakpoints as soon as your program stops there. | |
2712 | @end table | |
2713 | ||
d4f3574e SS |
2714 | @c FIXME: I think the following ``Except for [...] @code{tbreak}'' is |
2715 | @c confusing: tbreak is also initially enabled. | |
c906108c SS |
2716 | Except for a breakpoint set with @code{tbreak} (@pxref{Set Breaks, |
2717 | ,Setting breakpoints}), breakpoints that you set are initially enabled; | |
2718 | subsequently, they become disabled or enabled only when you use one of | |
2719 | the commands above. (The command @code{until} can set and delete a | |
2720 | breakpoint of its own, but it does not change the state of your other | |
2721 | breakpoints; see @ref{Continuing and Stepping, ,Continuing and | |
2722 | stepping}.) | |
2723 | ||
53a5351d | 2724 | @node Conditions |
c906108c SS |
2725 | @subsection Break conditions |
2726 | @cindex conditional breakpoints | |
2727 | @cindex breakpoint conditions | |
2728 | ||
2729 | @c FIXME what is scope of break condition expr? Context where wanted? | |
2730 | @c in particular for a watchpoint? | |
2731 | The simplest sort of breakpoint breaks every time your program reaches a | |
2732 | specified place. You can also specify a @dfn{condition} for a | |
2733 | breakpoint. A condition is just a Boolean expression in your | |
2734 | programming language (@pxref{Expressions, ,Expressions}). A breakpoint with | |
2735 | a condition evaluates the expression each time your program reaches it, | |
2736 | and your program stops only if the condition is @emph{true}. | |
2737 | ||
2738 | This is the converse of using assertions for program validation; in that | |
2739 | situation, you want to stop when the assertion is violated---that is, | |
2740 | when the condition is false. In C, if you want to test an assertion expressed | |
2741 | by the condition @var{assert}, you should set the condition | |
2742 | @samp{! @var{assert}} on the appropriate breakpoint. | |
2743 | ||
2744 | Conditions are also accepted for watchpoints; you may not need them, | |
2745 | since a watchpoint is inspecting the value of an expression anyhow---but | |
2746 | it might be simpler, say, to just set a watchpoint on a variable name, | |
2747 | and specify a condition that tests whether the new value is an interesting | |
2748 | one. | |
2749 | ||
2750 | Break conditions can have side effects, and may even call functions in | |
2751 | your program. This can be useful, for example, to activate functions | |
2752 | that log program progress, or to use your own print functions to | |
2753 | format special data structures. The effects are completely predictable | |
2754 | unless there is another enabled breakpoint at the same address. (In | |
2755 | that case, @value{GDBN} might see the other breakpoint first and stop your | |
2756 | program without checking the condition of this one.) Note that | |
d4f3574e SS |
2757 | breakpoint commands are usually more convenient and flexible than break |
2758 | conditions for the | |
c906108c SS |
2759 | purpose of performing side effects when a breakpoint is reached |
2760 | (@pxref{Break Commands, ,Breakpoint command lists}). | |
2761 | ||
2762 | Break conditions can be specified when a breakpoint is set, by using | |
2763 | @samp{if} in the arguments to the @code{break} command. @xref{Set | |
2764 | Breaks, ,Setting breakpoints}. They can also be changed at any time | |
2765 | with the @code{condition} command. | |
53a5351d | 2766 | |
c906108c SS |
2767 | You can also use the @code{if} keyword with the @code{watch} command. |
2768 | The @code{catch} command does not recognize the @code{if} keyword; | |
2769 | @code{condition} is the only way to impose a further condition on a | |
2770 | catchpoint. | |
c906108c SS |
2771 | |
2772 | @table @code | |
2773 | @kindex condition | |
2774 | @item condition @var{bnum} @var{expression} | |
2775 | Specify @var{expression} as the break condition for breakpoint, | |
2776 | watchpoint, or catchpoint number @var{bnum}. After you set a condition, | |
2777 | breakpoint @var{bnum} stops your program only if the value of | |
2778 | @var{expression} is true (nonzero, in C). When you use | |
2779 | @code{condition}, @value{GDBN} checks @var{expression} immediately for | |
2780 | syntactic correctness, and to determine whether symbols in it have | |
d4f3574e SS |
2781 | referents in the context of your breakpoint. If @var{expression} uses |
2782 | symbols not referenced in the context of the breakpoint, @value{GDBN} | |
2783 | prints an error message: | |
2784 | ||
2785 | @example | |
2786 | No symbol "foo" in current context. | |
2787 | @end example | |
2788 | ||
2789 | @noindent | |
c906108c SS |
2790 | @value{GDBN} does |
2791 | not actually evaluate @var{expression} at the time the @code{condition} | |
d4f3574e SS |
2792 | command (or a command that sets a breakpoint with a condition, like |
2793 | @code{break if @dots{}}) is given, however. @xref{Expressions, ,Expressions}. | |
c906108c SS |
2794 | |
2795 | @item condition @var{bnum} | |
2796 | Remove the condition from breakpoint number @var{bnum}. It becomes | |
2797 | an ordinary unconditional breakpoint. | |
2798 | @end table | |
2799 | ||
2800 | @cindex ignore count (of breakpoint) | |
2801 | A special case of a breakpoint condition is to stop only when the | |
2802 | breakpoint has been reached a certain number of times. This is so | |
2803 | useful that there is a special way to do it, using the @dfn{ignore | |
2804 | count} of the breakpoint. Every breakpoint has an ignore count, which | |
2805 | is an integer. Most of the time, the ignore count is zero, and | |
2806 | therefore has no effect. But if your program reaches a breakpoint whose | |
2807 | ignore count is positive, then instead of stopping, it just decrements | |
2808 | the ignore count by one and continues. As a result, if the ignore count | |
2809 | value is @var{n}, the breakpoint does not stop the next @var{n} times | |
2810 | your program reaches it. | |
2811 | ||
2812 | @table @code | |
2813 | @kindex ignore | |
2814 | @item ignore @var{bnum} @var{count} | |
2815 | Set the ignore count of breakpoint number @var{bnum} to @var{count}. | |
2816 | The next @var{count} times the breakpoint is reached, your program's | |
2817 | execution does not stop; other than to decrement the ignore count, @value{GDBN} | |
2818 | takes no action. | |
2819 | ||
2820 | To make the breakpoint stop the next time it is reached, specify | |
2821 | a count of zero. | |
2822 | ||
2823 | When you use @code{continue} to resume execution of your program from a | |
2824 | breakpoint, you can specify an ignore count directly as an argument to | |
2825 | @code{continue}, rather than using @code{ignore}. @xref{Continuing and | |
2826 | Stepping,,Continuing and stepping}. | |
2827 | ||
2828 | If a breakpoint has a positive ignore count and a condition, the | |
2829 | condition is not checked. Once the ignore count reaches zero, | |
2830 | @value{GDBN} resumes checking the condition. | |
2831 | ||
2832 | You could achieve the effect of the ignore count with a condition such | |
2833 | as @w{@samp{$foo-- <= 0}} using a debugger convenience variable that | |
2834 | is decremented each time. @xref{Convenience Vars, ,Convenience | |
2835 | variables}. | |
2836 | @end table | |
2837 | ||
2838 | Ignore counts apply to breakpoints, watchpoints, and catchpoints. | |
2839 | ||
2840 | ||
53a5351d | 2841 | @node Break Commands |
c906108c SS |
2842 | @subsection Breakpoint command lists |
2843 | ||
2844 | @cindex breakpoint commands | |
2845 | You can give any breakpoint (or watchpoint or catchpoint) a series of | |
2846 | commands to execute when your program stops due to that breakpoint. For | |
2847 | example, you might want to print the values of certain expressions, or | |
2848 | enable other breakpoints. | |
2849 | ||
2850 | @table @code | |
2851 | @kindex commands | |
2852 | @kindex end | |
2853 | @item commands @r{[}@var{bnum}@r{]} | |
2854 | @itemx @dots{} @var{command-list} @dots{} | |
2855 | @itemx end | |
2856 | Specify a list of commands for breakpoint number @var{bnum}. The commands | |
2857 | themselves appear on the following lines. Type a line containing just | |
2858 | @code{end} to terminate the commands. | |
2859 | ||
2860 | To remove all commands from a breakpoint, type @code{commands} and | |
2861 | follow it immediately with @code{end}; that is, give no commands. | |
2862 | ||
2863 | With no @var{bnum} argument, @code{commands} refers to the last | |
2864 | breakpoint, watchpoint, or catchpoint set (not to the breakpoint most | |
2865 | recently encountered). | |
2866 | @end table | |
2867 | ||
2868 | Pressing @key{RET} as a means of repeating the last @value{GDBN} command is | |
2869 | disabled within a @var{command-list}. | |
2870 | ||
2871 | You can use breakpoint commands to start your program up again. Simply | |
2872 | use the @code{continue} command, or @code{step}, or any other command | |
2873 | that resumes execution. | |
2874 | ||
2875 | Any other commands in the command list, after a command that resumes | |
2876 | execution, are ignored. This is because any time you resume execution | |
2877 | (even with a simple @code{next} or @code{step}), you may encounter | |
2878 | another breakpoint---which could have its own command list, leading to | |
2879 | ambiguities about which list to execute. | |
2880 | ||
2881 | @kindex silent | |
2882 | If the first command you specify in a command list is @code{silent}, the | |
2883 | usual message about stopping at a breakpoint is not printed. This may | |
2884 | be desirable for breakpoints that are to print a specific message and | |
2885 | then continue. If none of the remaining commands print anything, you | |
2886 | see no sign that the breakpoint was reached. @code{silent} is | |
2887 | meaningful only at the beginning of a breakpoint command list. | |
2888 | ||
2889 | The commands @code{echo}, @code{output}, and @code{printf} allow you to | |
2890 | print precisely controlled output, and are often useful in silent | |
2891 | breakpoints. @xref{Output, ,Commands for controlled output}. | |
2892 | ||
2893 | For example, here is how you could use breakpoint commands to print the | |
2894 | value of @code{x} at entry to @code{foo} whenever @code{x} is positive. | |
2895 | ||
2896 | @example | |
2897 | break foo if x>0 | |
2898 | commands | |
2899 | silent | |
2900 | printf "x is %d\n",x | |
2901 | cont | |
2902 | end | |
2903 | @end example | |
2904 | ||
2905 | One application for breakpoint commands is to compensate for one bug so | |
2906 | you can test for another. Put a breakpoint just after the erroneous line | |
2907 | of code, give it a condition to detect the case in which something | |
2908 | erroneous has been done, and give it commands to assign correct values | |
2909 | to any variables that need them. End with the @code{continue} command | |
2910 | so that your program does not stop, and start with the @code{silent} | |
2911 | command so that no output is produced. Here is an example: | |
2912 | ||
2913 | @example | |
2914 | break 403 | |
2915 | commands | |
2916 | silent | |
2917 | set x = y + 4 | |
2918 | cont | |
2919 | end | |
2920 | @end example | |
2921 | ||
53a5351d | 2922 | @node Breakpoint Menus |
c906108c SS |
2923 | @subsection Breakpoint menus |
2924 | @cindex overloading | |
2925 | @cindex symbol overloading | |
2926 | ||
2927 | Some programming languages (notably C++) permit a single function name | |
2928 | to be defined several times, for application in different contexts. | |
2929 | This is called @dfn{overloading}. When a function name is overloaded, | |
2930 | @samp{break @var{function}} is not enough to tell @value{GDBN} where you want | |
2931 | a breakpoint. If you realize this is a problem, you can use | |
2932 | something like @samp{break @var{function}(@var{types})} to specify which | |
2933 | particular version of the function you want. Otherwise, @value{GDBN} offers | |
2934 | you a menu of numbered choices for different possible breakpoints, and | |
2935 | waits for your selection with the prompt @samp{>}. The first two | |
2936 | options are always @samp{[0] cancel} and @samp{[1] all}. Typing @kbd{1} | |
2937 | sets a breakpoint at each definition of @var{function}, and typing | |
2938 | @kbd{0} aborts the @code{break} command without setting any new | |
2939 | breakpoints. | |
2940 | ||
2941 | For example, the following session excerpt shows an attempt to set a | |
2942 | breakpoint at the overloaded symbol @code{String::after}. | |
2943 | We choose three particular definitions of that function name: | |
2944 | ||
2945 | @c FIXME! This is likely to change to show arg type lists, at least | |
2946 | @smallexample | |
2947 | @group | |
2948 | (@value{GDBP}) b String::after | |
2949 | [0] cancel | |
2950 | [1] all | |
2951 | [2] file:String.cc; line number:867 | |
2952 | [3] file:String.cc; line number:860 | |
2953 | [4] file:String.cc; line number:875 | |
2954 | [5] file:String.cc; line number:853 | |
2955 | [6] file:String.cc; line number:846 | |
2956 | [7] file:String.cc; line number:735 | |
2957 | > 2 4 6 | |
2958 | Breakpoint 1 at 0xb26c: file String.cc, line 867. | |
2959 | Breakpoint 2 at 0xb344: file String.cc, line 875. | |
2960 | Breakpoint 3 at 0xafcc: file String.cc, line 846. | |
2961 | Multiple breakpoints were set. | |
2962 | Use the "delete" command to delete unwanted | |
2963 | breakpoints. | |
2964 | (@value{GDBP}) | |
2965 | @end group | |
2966 | @end smallexample | |
c906108c SS |
2967 | |
2968 | @c @ifclear BARETARGET | |
d4f3574e SS |
2969 | @node Error in Breakpoints |
2970 | @subsection ``Cannot insert breakpoints'' | |
c906108c SS |
2971 | @c |
2972 | @c FIXME!! 14/6/95 Is there a real example of this? Let's use it. | |
2973 | @c | |
d4f3574e SS |
2974 | Under some operating systems, breakpoints cannot be used in a program if |
2975 | any other process is running that program. In this situation, | |
2976 | attempting to run or continue a program with a breakpoint causes | |
2977 | @value{GDBN} to print an error message: | |
2978 | ||
2979 | @example | |
2980 | Cannot insert breakpoints. | |
2981 | The same program may be running in another process. | |
2982 | @end example | |
2983 | ||
2984 | When this happens, you have three ways to proceed: | |
2985 | ||
2986 | @enumerate | |
2987 | @item | |
2988 | Remove or disable the breakpoints, then continue. | |
2989 | ||
2990 | @item | |
2991 | Suspend @value{GDBN}, and copy the file containing your program to a new | |
2992 | name. Resume @value{GDBN} and use the @code{exec-file} command to specify | |
2993 | that @value{GDBN} should run your program under that name. | |
2994 | Then start your program again. | |
2995 | ||
2996 | @item | |
2997 | Relink your program so that the text segment is nonsharable, using the | |
2998 | linker option @samp{-N}. The operating system limitation may not apply | |
2999 | to nonsharable executables. | |
3000 | @end enumerate | |
c906108c SS |
3001 | @c @end ifclear |
3002 | ||
d4f3574e SS |
3003 | A similar message can be printed if you request too many active |
3004 | hardware-assisted breakpoints and watchpoints: | |
3005 | ||
3006 | @c FIXME: the precise wording of this message may change; the relevant | |
3007 | @c source change is not committed yet (Sep 3, 1999). | |
3008 | @smallexample | |
3009 | Stopped; cannot insert breakpoints. | |
3010 | You may have requested too many hardware breakpoints and watchpoints. | |
3011 | @end smallexample | |
3012 | ||
3013 | @noindent | |
3014 | This message is printed when you attempt to resume the program, since | |
3015 | only then @value{GDBN} knows exactly how many hardware breakpoints and | |
3016 | watchpoints it needs to insert. | |
3017 | ||
3018 | When this message is printed, you need to disable or remove some of the | |
3019 | hardware-assisted breakpoints and watchpoints, and then continue. | |
3020 | ||
3021 | ||
53a5351d | 3022 | @node Continuing and Stepping |
c906108c SS |
3023 | @section Continuing and stepping |
3024 | ||
3025 | @cindex stepping | |
3026 | @cindex continuing | |
3027 | @cindex resuming execution | |
3028 | @dfn{Continuing} means resuming program execution until your program | |
3029 | completes normally. In contrast, @dfn{stepping} means executing just | |
3030 | one more ``step'' of your program, where ``step'' may mean either one | |
3031 | line of source code, or one machine instruction (depending on what | |
7a292a7a SS |
3032 | particular command you use). Either when continuing or when stepping, |
3033 | your program may stop even sooner, due to a breakpoint or a signal. (If | |
d4f3574e SS |
3034 | it stops due to a signal, you may want to use @code{handle}, or use |
3035 | @samp{signal 0} to resume execution. @xref{Signals, ,Signals}.) | |
c906108c SS |
3036 | |
3037 | @table @code | |
3038 | @kindex continue | |
3039 | @kindex c | |
3040 | @kindex fg | |
3041 | @item continue @r{[}@var{ignore-count}@r{]} | |
3042 | @itemx c @r{[}@var{ignore-count}@r{]} | |
3043 | @itemx fg @r{[}@var{ignore-count}@r{]} | |
3044 | Resume program execution, at the address where your program last stopped; | |
3045 | any breakpoints set at that address are bypassed. The optional argument | |
3046 | @var{ignore-count} allows you to specify a further number of times to | |
3047 | ignore a breakpoint at this location; its effect is like that of | |
3048 | @code{ignore} (@pxref{Conditions, ,Break conditions}). | |
3049 | ||
3050 | The argument @var{ignore-count} is meaningful only when your program | |
3051 | stopped due to a breakpoint. At other times, the argument to | |
3052 | @code{continue} is ignored. | |
3053 | ||
d4f3574e SS |
3054 | The synonyms @code{c} and @code{fg} (for @dfn{foreground}, as the |
3055 | debugged program is deemed to be the foreground program) are provided | |
3056 | purely for convenience, and have exactly the same behavior as | |
3057 | @code{continue}. | |
c906108c SS |
3058 | @end table |
3059 | ||
3060 | To resume execution at a different place, you can use @code{return} | |
3061 | (@pxref{Returning, ,Returning from a function}) to go back to the | |
3062 | calling function; or @code{jump} (@pxref{Jumping, ,Continuing at a | |
3063 | different address}) to go to an arbitrary location in your program. | |
3064 | ||
3065 | A typical technique for using stepping is to set a breakpoint | |
3066 | (@pxref{Breakpoints, ,Breakpoints; watchpoints; and catchpoints}) at the | |
3067 | beginning of the function or the section of your program where a problem | |
3068 | is believed to lie, run your program until it stops at that breakpoint, | |
3069 | and then step through the suspect area, examining the variables that are | |
3070 | interesting, until you see the problem happen. | |
3071 | ||
3072 | @table @code | |
3073 | @kindex step | |
3074 | @kindex s | |
3075 | @item step | |
3076 | Continue running your program until control reaches a different source | |
3077 | line, then stop it and return control to @value{GDBN}. This command is | |
3078 | abbreviated @code{s}. | |
3079 | ||
3080 | @quotation | |
3081 | @c "without debugging information" is imprecise; actually "without line | |
3082 | @c numbers in the debugging information". (gcc -g1 has debugging info but | |
3083 | @c not line numbers). But it seems complex to try to make that | |
3084 | @c distinction here. | |
3085 | @emph{Warning:} If you use the @code{step} command while control is | |
3086 | within a function that was compiled without debugging information, | |
3087 | execution proceeds until control reaches a function that does have | |
3088 | debugging information. Likewise, it will not step into a function which | |
3089 | is compiled without debugging information. To step through functions | |
3090 | without debugging information, use the @code{stepi} command, described | |
3091 | below. | |
3092 | @end quotation | |
3093 | ||
d4f3574e SS |
3094 | The @code{step} command only stops at the first instruction of a |
3095 | source line. This prevents the multiple stops that could otherwise occur in | |
c906108c SS |
3096 | switch statements, for loops, etc. @code{step} continues to stop if a |
3097 | function that has debugging information is called within the line. | |
d4f3574e SS |
3098 | In other words, @code{step} @emph{steps inside} any functions called |
3099 | within the line. | |
c906108c | 3100 | |
d4f3574e SS |
3101 | Also, the @code{step} command only enters a function if there is line |
3102 | number information for the function. Otherwise it acts like the | |
c906108c SS |
3103 | @code{next} command. This avoids problems when using @code{cc -gl} |
3104 | on MIPS machines. Previously, @code{step} entered subroutines if there | |
3105 | was any debugging information about the routine. | |
3106 | ||
3107 | @item step @var{count} | |
3108 | Continue running as in @code{step}, but do so @var{count} times. If a | |
7a292a7a SS |
3109 | breakpoint is reached, or a signal not related to stepping occurs before |
3110 | @var{count} steps, stepping stops right away. | |
c906108c SS |
3111 | |
3112 | @kindex next | |
3113 | @kindex n | |
3114 | @item next @r{[}@var{count}@r{]} | |
3115 | Continue to the next source line in the current (innermost) stack frame. | |
7a292a7a SS |
3116 | This is similar to @code{step}, but function calls that appear within |
3117 | the line of code are executed without stopping. Execution stops when | |
3118 | control reaches a different line of code at the original stack level | |
3119 | that was executing when you gave the @code{next} command. This command | |
3120 | is abbreviated @code{n}. | |
c906108c SS |
3121 | |
3122 | An argument @var{count} is a repeat count, as for @code{step}. | |
3123 | ||
3124 | ||
3125 | @c FIX ME!! Do we delete this, or is there a way it fits in with | |
3126 | @c the following paragraph? --- Vctoria | |
3127 | @c | |
3128 | @c @code{next} within a function that lacks debugging information acts like | |
3129 | @c @code{step}, but any function calls appearing within the code of the | |
3130 | @c function are executed without stopping. | |
3131 | ||
d4f3574e SS |
3132 | The @code{next} command only stops at the first instruction of a |
3133 | source line. This prevents multiple stops that could otherwise occur in | |
c906108c SS |
3134 | switch statements, for loops, etc. |
3135 | ||
3136 | @kindex finish | |
3137 | @item finish | |
3138 | Continue running until just after function in the selected stack frame | |
3139 | returns. Print the returned value (if any). | |
3140 | ||
3141 | Contrast this with the @code{return} command (@pxref{Returning, | |
3142 | ,Returning from a function}). | |
3143 | ||
3144 | @kindex until | |
3145 | @kindex u | |
3146 | @item until | |
3147 | @itemx u | |
3148 | Continue running until a source line past the current line, in the | |
3149 | current stack frame, is reached. This command is used to avoid single | |
3150 | stepping through a loop more than once. It is like the @code{next} | |
3151 | command, except that when @code{until} encounters a jump, it | |
3152 | automatically continues execution until the program counter is greater | |
3153 | than the address of the jump. | |
3154 | ||
3155 | This means that when you reach the end of a loop after single stepping | |
3156 | though it, @code{until} makes your program continue execution until it | |
3157 | exits the loop. In contrast, a @code{next} command at the end of a loop | |
3158 | simply steps back to the beginning of the loop, which forces you to step | |
3159 | through the next iteration. | |
3160 | ||
3161 | @code{until} always stops your program if it attempts to exit the current | |
3162 | stack frame. | |
3163 | ||
3164 | @code{until} may produce somewhat counterintuitive results if the order | |
3165 | of machine code does not match the order of the source lines. For | |
3166 | example, in the following excerpt from a debugging session, the @code{f} | |
3167 | (@code{frame}) command shows that execution is stopped at line | |
3168 | @code{206}; yet when we use @code{until}, we get to line @code{195}: | |
3169 | ||
3170 | @example | |
3171 | (@value{GDBP}) f | |
3172 | #0 main (argc=4, argv=0xf7fffae8) at m4.c:206 | |
3173 | 206 expand_input(); | |
3174 | (@value{GDBP}) until | |
3175 | 195 for ( ; argc > 0; NEXTARG) @{ | |
3176 | @end example | |
3177 | ||
3178 | This happened because, for execution efficiency, the compiler had | |
3179 | generated code for the loop closure test at the end, rather than the | |
3180 | start, of the loop---even though the test in a C @code{for}-loop is | |
3181 | written before the body of the loop. The @code{until} command appeared | |
3182 | to step back to the beginning of the loop when it advanced to this | |
3183 | expression; however, it has not really gone to an earlier | |
3184 | statement---not in terms of the actual machine code. | |
3185 | ||
3186 | @code{until} with no argument works by means of single | |
3187 | instruction stepping, and hence is slower than @code{until} with an | |
3188 | argument. | |
3189 | ||
3190 | @item until @var{location} | |
3191 | @itemx u @var{location} | |
3192 | Continue running your program until either the specified location is | |
3193 | reached, or the current stack frame returns. @var{location} is any of | |
3194 | the forms of argument acceptable to @code{break} (@pxref{Set Breaks, | |
3195 | ,Setting breakpoints}). This form of the command uses breakpoints, | |
3196 | and hence is quicker than @code{until} without an argument. | |
3197 | ||
3198 | @kindex stepi | |
3199 | @kindex si | |
3200 | @item stepi | |
3201 | @itemx si | |
3202 | Execute one machine instruction, then stop and return to the debugger. | |
3203 | ||
3204 | It is often useful to do @samp{display/i $pc} when stepping by machine | |
3205 | instructions. This makes @value{GDBN} automatically display the next | |
3206 | instruction to be executed, each time your program stops. @xref{Auto | |
3207 | Display,, Automatic display}. | |
3208 | ||
3209 | An argument is a repeat count, as in @code{step}. | |
3210 | ||
3211 | @need 750 | |
3212 | @kindex nexti | |
3213 | @kindex ni | |
3214 | @item nexti | |
3215 | @itemx ni | |
3216 | Execute one machine instruction, but if it is a function call, | |
3217 | proceed until the function returns. | |
3218 | ||
3219 | An argument is a repeat count, as in @code{next}. | |
3220 | @end table | |
3221 | ||
53a5351d | 3222 | @node Signals |
c906108c SS |
3223 | @section Signals |
3224 | @cindex signals | |
3225 | ||
3226 | A signal is an asynchronous event that can happen in a program. The | |
3227 | operating system defines the possible kinds of signals, and gives each | |
3228 | kind a name and a number. For example, in Unix @code{SIGINT} is the | |
d4f3574e | 3229 | signal a program gets when you type an interrupt character (often @kbd{C-c}); |
c906108c SS |
3230 | @code{SIGSEGV} is the signal a program gets from referencing a place in |
3231 | memory far away from all the areas in use; @code{SIGALRM} occurs when | |
3232 | the alarm clock timer goes off (which happens only if your program has | |
3233 | requested an alarm). | |
3234 | ||
3235 | @cindex fatal signals | |
3236 | Some signals, including @code{SIGALRM}, are a normal part of the | |
3237 | functioning of your program. Others, such as @code{SIGSEGV}, indicate | |
d4f3574e | 3238 | errors; these signals are @dfn{fatal} (they kill your program immediately) if the |
c906108c SS |
3239 | program has not specified in advance some other way to handle the signal. |
3240 | @code{SIGINT} does not indicate an error in your program, but it is normally | |
3241 | fatal so it can carry out the purpose of the interrupt: to kill the program. | |
3242 | ||
3243 | @value{GDBN} has the ability to detect any occurrence of a signal in your | |
3244 | program. You can tell @value{GDBN} in advance what to do for each kind of | |
3245 | signal. | |
3246 | ||
3247 | @cindex handling signals | |
3248 | Normally, @value{GDBN} is set up to ignore non-erroneous signals like @code{SIGALRM} | |
3249 | (so as not to interfere with their role in the functioning of your program) | |
3250 | but to stop your program immediately whenever an error signal happens. | |
3251 | You can change these settings with the @code{handle} command. | |
3252 | ||
3253 | @table @code | |
3254 | @kindex info signals | |
3255 | @item info signals | |
3256 | Print a table of all the kinds of signals and how @value{GDBN} has been told to | |
3257 | handle each one. You can use this to see the signal numbers of all | |
3258 | the defined types of signals. | |
3259 | ||
d4f3574e | 3260 | @code{info handle} is an alias for @code{info signals}. |
c906108c SS |
3261 | |
3262 | @kindex handle | |
3263 | @item handle @var{signal} @var{keywords}@dots{} | |
3264 | Change the way @value{GDBN} handles signal @var{signal}. @var{signal} can | |
3265 | be the number of a signal or its name (with or without the @samp{SIG} at the | |
3266 | beginning). The @var{keywords} say what change to make. | |
3267 | @end table | |
3268 | ||
3269 | @c @group | |
3270 | The keywords allowed by the @code{handle} command can be abbreviated. | |
3271 | Their full names are: | |
3272 | ||
3273 | @table @code | |
3274 | @item nostop | |
3275 | @value{GDBN} should not stop your program when this signal happens. It may | |
3276 | still print a message telling you that the signal has come in. | |
3277 | ||
3278 | @item stop | |
3279 | @value{GDBN} should stop your program when this signal happens. This implies | |
3280 | the @code{print} keyword as well. | |
3281 | ||
3282 | @item print | |
3283 | @value{GDBN} should print a message when this signal happens. | |
3284 | ||
3285 | @item noprint | |
3286 | @value{GDBN} should not mention the occurrence of the signal at all. This | |
3287 | implies the @code{nostop} keyword as well. | |
3288 | ||
3289 | @item pass | |
3290 | @value{GDBN} should allow your program to see this signal; your program | |
3291 | can handle the signal, or else it may terminate if the signal is fatal | |
3292 | and not handled. | |
3293 | ||
3294 | @item nopass | |
3295 | @value{GDBN} should not allow your program to see this signal. | |
3296 | @end table | |
3297 | @c @end group | |
3298 | ||
d4f3574e SS |
3299 | When a signal stops your program, the signal is not visible to the |
3300 | program until you | |
c906108c SS |
3301 | continue. Your program sees the signal then, if @code{pass} is in |
3302 | effect for the signal in question @emph{at that time}. In other words, | |
3303 | after @value{GDBN} reports a signal, you can use the @code{handle} | |
3304 | command with @code{pass} or @code{nopass} to control whether your | |
3305 | program sees that signal when you continue. | |
3306 | ||
3307 | You can also use the @code{signal} command to prevent your program from | |
3308 | seeing a signal, or cause it to see a signal it normally would not see, | |
3309 | or to give it any signal at any time. For example, if your program stopped | |
3310 | due to some sort of memory reference error, you might store correct | |
3311 | values into the erroneous variables and continue, hoping to see more | |
3312 | execution; but your program would probably terminate immediately as | |
3313 | a result of the fatal signal once it saw the signal. To prevent this, | |
3314 | you can continue with @samp{signal 0}. @xref{Signaling, ,Giving your | |
3315 | program a signal}. | |
c906108c | 3316 | |
53a5351d | 3317 | @node Thread Stops |
c906108c SS |
3318 | @section Stopping and starting multi-thread programs |
3319 | ||
3320 | When your program has multiple threads (@pxref{Threads,, Debugging | |
3321 | programs with multiple threads}), you can choose whether to set | |
3322 | breakpoints on all threads, or on a particular thread. | |
3323 | ||
3324 | @table @code | |
3325 | @cindex breakpoints and threads | |
3326 | @cindex thread breakpoints | |
3327 | @kindex break @dots{} thread @var{threadno} | |
3328 | @item break @var{linespec} thread @var{threadno} | |
3329 | @itemx break @var{linespec} thread @var{threadno} if @dots{} | |
3330 | @var{linespec} specifies source lines; there are several ways of | |
3331 | writing them, but the effect is always to specify some source line. | |
3332 | ||
3333 | Use the qualifier @samp{thread @var{threadno}} with a breakpoint command | |
3334 | to specify that you only want @value{GDBN} to stop the program when a | |
3335 | particular thread reaches this breakpoint. @var{threadno} is one of the | |
3336 | numeric thread identifiers assigned by @value{GDBN}, shown in the first | |
3337 | column of the @samp{info threads} display. | |
3338 | ||
3339 | If you do not specify @samp{thread @var{threadno}} when you set a | |
3340 | breakpoint, the breakpoint applies to @emph{all} threads of your | |
3341 | program. | |
3342 | ||
3343 | You can use the @code{thread} qualifier on conditional breakpoints as | |
3344 | well; in this case, place @samp{thread @var{threadno}} before the | |
3345 | breakpoint condition, like this: | |
3346 | ||
3347 | @smallexample | |
2df3850c | 3348 | (@value{GDBP}) break frik.c:13 thread 28 if bartab > lim |
c906108c SS |
3349 | @end smallexample |
3350 | ||
3351 | @end table | |
3352 | ||
3353 | @cindex stopped threads | |
3354 | @cindex threads, stopped | |
3355 | Whenever your program stops under @value{GDBN} for any reason, | |
3356 | @emph{all} threads of execution stop, not just the current thread. This | |
3357 | allows you to examine the overall state of the program, including | |
3358 | switching between threads, without worrying that things may change | |
3359 | underfoot. | |
3360 | ||
3361 | @cindex continuing threads | |
3362 | @cindex threads, continuing | |
3363 | Conversely, whenever you restart the program, @emph{all} threads start | |
3364 | executing. @emph{This is true even when single-stepping} with commands | |
3365 | like @code{step} or @code{next}. | |
3366 | ||
3367 | In particular, @value{GDBN} cannot single-step all threads in lockstep. | |
3368 | Since thread scheduling is up to your debugging target's operating | |
3369 | system (not controlled by @value{GDBN}), other threads may | |
3370 | execute more than one statement while the current thread completes a | |
3371 | single step. Moreover, in general other threads stop in the middle of a | |
3372 | statement, rather than at a clean statement boundary, when the program | |
3373 | stops. | |
3374 | ||
3375 | You might even find your program stopped in another thread after | |
3376 | continuing or even single-stepping. This happens whenever some other | |
3377 | thread runs into a breakpoint, a signal, or an exception before the | |
3378 | first thread completes whatever you requested. | |
3379 | ||
3380 | On some OSes, you can lock the OS scheduler and thus allow only a single | |
3381 | thread to run. | |
3382 | ||
3383 | @table @code | |
3384 | @item set scheduler-locking @var{mode} | |
3385 | Set the scheduler locking mode. If it is @code{off}, then there is no | |
3386 | locking and any thread may run at any time. If @code{on}, then only the | |
3387 | current thread may run when the inferior is resumed. The @code{step} | |
3388 | mode optimizes for single-stepping. It stops other threads from | |
3389 | ``seizing the prompt'' by preempting the current thread while you are | |
3390 | stepping. Other threads will only rarely (or never) get a chance to run | |
d4f3574e | 3391 | when you step. They are more likely to run when you @samp{next} over a |
c906108c | 3392 | function call, and they are completely free to run when you use commands |
d4f3574e | 3393 | like @samp{continue}, @samp{until}, or @samp{finish}. However, unless another |
c906108c | 3394 | thread hits a breakpoint during its timeslice, they will never steal the |
2df3850c | 3395 | @value{GDBN} prompt away from the thread that you are debugging. |
c906108c SS |
3396 | |
3397 | @item show scheduler-locking | |
3398 | Display the current scheduler locking mode. | |
3399 | @end table | |
3400 | ||
c906108c | 3401 | |
53a5351d | 3402 | @node Stack |
c906108c SS |
3403 | @chapter Examining the Stack |
3404 | ||
3405 | When your program has stopped, the first thing you need to know is where it | |
3406 | stopped and how it got there. | |
3407 | ||
3408 | @cindex call stack | |
3409 | Each time your program performs a function call, information about the call | |
3410 | is generated. | |
3411 | That information includes the location of the call in your program, | |
3412 | the arguments of the call, | |
3413 | and the local variables of the function being called. | |
3414 | The information is saved in a block of data called a @dfn{stack frame}. | |
3415 | The stack frames are allocated in a region of memory called the @dfn{call | |
3416 | stack}. | |
3417 | ||
3418 | When your program stops, the @value{GDBN} commands for examining the | |
3419 | stack allow you to see all of this information. | |
3420 | ||
3421 | @cindex selected frame | |
3422 | One of the stack frames is @dfn{selected} by @value{GDBN} and many | |
3423 | @value{GDBN} commands refer implicitly to the selected frame. In | |
3424 | particular, whenever you ask @value{GDBN} for the value of a variable in | |
3425 | your program, the value is found in the selected frame. There are | |
3426 | special @value{GDBN} commands to select whichever frame you are | |
3427 | interested in. @xref{Selection, ,Selecting a frame}. | |
3428 | ||
3429 | When your program stops, @value{GDBN} automatically selects the | |
3430 | currently executing frame and describes it briefly, similar to the | |
3431 | @code{frame} command (@pxref{Frame Info, ,Information about a frame}). | |
3432 | ||
3433 | @menu | |
3434 | * Frames:: Stack frames | |
3435 | * Backtrace:: Backtraces | |
3436 | * Selection:: Selecting a frame | |
3437 | * Frame Info:: Information on a frame | |
c906108c SS |
3438 | |
3439 | @end menu | |
3440 | ||
53a5351d | 3441 | @node Frames |
c906108c SS |
3442 | @section Stack frames |
3443 | ||
d4f3574e | 3444 | @cindex frame, definition |
c906108c SS |
3445 | @cindex stack frame |
3446 | The call stack is divided up into contiguous pieces called @dfn{stack | |
3447 | frames}, or @dfn{frames} for short; each frame is the data associated | |
3448 | with one call to one function. The frame contains the arguments given | |
3449 | to the function, the function's local variables, and the address at | |
3450 | which the function is executing. | |
3451 | ||
3452 | @cindex initial frame | |
3453 | @cindex outermost frame | |
3454 | @cindex innermost frame | |
3455 | When your program is started, the stack has only one frame, that of the | |
3456 | function @code{main}. This is called the @dfn{initial} frame or the | |
3457 | @dfn{outermost} frame. Each time a function is called, a new frame is | |
3458 | made. Each time a function returns, the frame for that function invocation | |
3459 | is eliminated. If a function is recursive, there can be many frames for | |
3460 | the same function. The frame for the function in which execution is | |
3461 | actually occurring is called the @dfn{innermost} frame. This is the most | |
3462 | recently created of all the stack frames that still exist. | |
3463 | ||
3464 | @cindex frame pointer | |
3465 | Inside your program, stack frames are identified by their addresses. A | |
3466 | stack frame consists of many bytes, each of which has its own address; each | |
3467 | kind of computer has a convention for choosing one byte whose | |
3468 | address serves as the address of the frame. Usually this address is kept | |
3469 | in a register called the @dfn{frame pointer register} while execution is | |
3470 | going on in that frame. | |
3471 | ||
3472 | @cindex frame number | |
3473 | @value{GDBN} assigns numbers to all existing stack frames, starting with | |
3474 | zero for the innermost frame, one for the frame that called it, | |
3475 | and so on upward. These numbers do not really exist in your program; | |
3476 | they are assigned by @value{GDBN} to give you a way of designating stack | |
3477 | frames in @value{GDBN} commands. | |
3478 | ||
3479 | @c below produces an acceptable overful hbox. --mew 13aug1993 | |
3480 | @cindex frameless execution | |
3481 | Some compilers provide a way to compile functions so that they operate | |
3482 | without stack frames. (For example, the @code{@value{GCC}} option | |
3483 | @samp{-fomit-frame-pointer} generates functions without a frame.) | |
3484 | This is occasionally done with heavily used library functions to save | |
3485 | the frame setup time. @value{GDBN} has limited facilities for dealing | |
3486 | with these function invocations. If the innermost function invocation | |
3487 | has no stack frame, @value{GDBN} nevertheless regards it as though | |
3488 | it had a separate frame, which is numbered zero as usual, allowing | |
3489 | correct tracing of the function call chain. However, @value{GDBN} has | |
3490 | no provision for frameless functions elsewhere in the stack. | |
3491 | ||
3492 | @table @code | |
d4f3574e | 3493 | @kindex frame@r{, command} |
c906108c SS |
3494 | @item frame @var{args} |
3495 | The @code{frame} command allows you to move from one stack frame to another, | |
3496 | and to print the stack frame you select. @var{args} may be either the | |
3497 | address of the frame or the stack frame number. Without an argument, | |
3498 | @code{frame} prints the current stack frame. | |
3499 | ||
3500 | @kindex select-frame | |
3501 | @item select-frame | |
3502 | The @code{select-frame} command allows you to move from one stack frame | |
3503 | to another without printing the frame. This is the silent version of | |
3504 | @code{frame}. | |
3505 | @end table | |
3506 | ||
53a5351d | 3507 | @node Backtrace |
c906108c SS |
3508 | @section Backtraces |
3509 | ||
3510 | @cindex backtraces | |
3511 | @cindex tracebacks | |
3512 | @cindex stack traces | |
3513 | A backtrace is a summary of how your program got where it is. It shows one | |
3514 | line per frame, for many frames, starting with the currently executing | |
3515 | frame (frame zero), followed by its caller (frame one), and on up the | |
3516 | stack. | |
3517 | ||
3518 | @table @code | |
3519 | @kindex backtrace | |
3520 | @kindex bt | |
3521 | @item backtrace | |
3522 | @itemx bt | |
3523 | Print a backtrace of the entire stack: one line per frame for all | |
3524 | frames in the stack. | |
3525 | ||
3526 | You can stop the backtrace at any time by typing the system interrupt | |
3527 | character, normally @kbd{C-c}. | |
3528 | ||
3529 | @item backtrace @var{n} | |
3530 | @itemx bt @var{n} | |
3531 | Similar, but print only the innermost @var{n} frames. | |
3532 | ||
3533 | @item backtrace -@var{n} | |
3534 | @itemx bt -@var{n} | |
3535 | Similar, but print only the outermost @var{n} frames. | |
3536 | @end table | |
3537 | ||
3538 | @kindex where | |
3539 | @kindex info stack | |
3540 | @kindex info s | |
3541 | The names @code{where} and @code{info stack} (abbreviated @code{info s}) | |
3542 | are additional aliases for @code{backtrace}. | |
3543 | ||
3544 | Each line in the backtrace shows the frame number and the function name. | |
3545 | The program counter value is also shown---unless you use @code{set | |
3546 | print address off}. The backtrace also shows the source file name and | |
3547 | line number, as well as the arguments to the function. The program | |
3548 | counter value is omitted if it is at the beginning of the code for that | |
3549 | line number. | |
3550 | ||
3551 | Here is an example of a backtrace. It was made with the command | |
3552 | @samp{bt 3}, so it shows the innermost three frames. | |
3553 | ||
3554 | @smallexample | |
3555 | @group | |
3556 | #0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8) | |
3557 | at builtin.c:993 | |
3558 | #1 0x6e38 in expand_macro (sym=0x2b600) at macro.c:242 | |
3559 | #2 0x6840 in expand_token (obs=0x0, t=177664, td=0xf7fffb08) | |
3560 | at macro.c:71 | |
3561 | (More stack frames follow...) | |
3562 | @end group | |
3563 | @end smallexample | |
3564 | ||
3565 | @noindent | |
3566 | The display for frame zero does not begin with a program counter | |
3567 | value, indicating that your program has stopped at the beginning of the | |
3568 | code for line @code{993} of @code{builtin.c}. | |
3569 | ||
53a5351d | 3570 | @node Selection |
c906108c SS |
3571 | @section Selecting a frame |
3572 | ||
3573 | Most commands for examining the stack and other data in your program work on | |
3574 | whichever stack frame is selected at the moment. Here are the commands for | |
3575 | selecting a stack frame; all of them finish by printing a brief description | |
3576 | of the stack frame just selected. | |
3577 | ||
3578 | @table @code | |
d4f3574e | 3579 | @kindex frame@r{, selecting} |
c906108c SS |
3580 | @kindex f |
3581 | @item frame @var{n} | |
3582 | @itemx f @var{n} | |
3583 | Select frame number @var{n}. Recall that frame zero is the innermost | |
3584 | (currently executing) frame, frame one is the frame that called the | |
3585 | innermost one, and so on. The highest-numbered frame is the one for | |
3586 | @code{main}. | |
3587 | ||
3588 | @item frame @var{addr} | |
3589 | @itemx f @var{addr} | |
3590 | Select the frame at address @var{addr}. This is useful mainly if the | |
3591 | chaining of stack frames has been damaged by a bug, making it | |
3592 | impossible for @value{GDBN} to assign numbers properly to all frames. In | |
3593 | addition, this can be useful when your program has multiple stacks and | |
3594 | switches between them. | |
3595 | ||
c906108c SS |
3596 | On the SPARC architecture, @code{frame} needs two addresses to |
3597 | select an arbitrary frame: a frame pointer and a stack pointer. | |
3598 | ||
3599 | On the MIPS and Alpha architecture, it needs two addresses: a stack | |
3600 | pointer and a program counter. | |
3601 | ||
3602 | On the 29k architecture, it needs three addresses: a register stack | |
3603 | pointer, a program counter, and a memory stack pointer. | |
3604 | @c note to future updaters: this is conditioned on a flag | |
3605 | @c SETUP_ARBITRARY_FRAME in the tm-*.h files. The above is up to date | |
3606 | @c as of 27 Jan 1994. | |
c906108c SS |
3607 | |
3608 | @kindex up | |
3609 | @item up @var{n} | |
3610 | Move @var{n} frames up the stack. For positive numbers @var{n}, this | |
3611 | advances toward the outermost frame, to higher frame numbers, to frames | |
3612 | that have existed longer. @var{n} defaults to one. | |
3613 | ||
3614 | @kindex down | |
3615 | @kindex do | |
3616 | @item down @var{n} | |
3617 | Move @var{n} frames down the stack. For positive numbers @var{n}, this | |
3618 | advances toward the innermost frame, to lower frame numbers, to frames | |
3619 | that were created more recently. @var{n} defaults to one. You may | |
3620 | abbreviate @code{down} as @code{do}. | |
3621 | @end table | |
3622 | ||
3623 | All of these commands end by printing two lines of output describing the | |
3624 | frame. The first line shows the frame number, the function name, the | |
3625 | arguments, and the source file and line number of execution in that | |
3626 | frame. The second line shows the text of that source line. | |
3627 | ||
3628 | @need 1000 | |
3629 | For example: | |
3630 | ||
3631 | @smallexample | |
3632 | @group | |
3633 | (@value{GDBP}) up | |
3634 | #1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc) | |
3635 | at env.c:10 | |
3636 | 10 read_input_file (argv[i]); | |
3637 | @end group | |
3638 | @end smallexample | |
3639 | ||
3640 | After such a printout, the @code{list} command with no arguments | |
3641 | prints ten lines centered on the point of execution in the frame. | |
3642 | @xref{List, ,Printing source lines}. | |
3643 | ||
3644 | @table @code | |
3645 | @kindex down-silently | |
3646 | @kindex up-silently | |
3647 | @item up-silently @var{n} | |
3648 | @itemx down-silently @var{n} | |
3649 | These two commands are variants of @code{up} and @code{down}, | |
3650 | respectively; they differ in that they do their work silently, without | |
3651 | causing display of the new frame. They are intended primarily for use | |
3652 | in @value{GDBN} command scripts, where the output might be unnecessary and | |
3653 | distracting. | |
3654 | @end table | |
3655 | ||
53a5351d | 3656 | @node Frame Info |
c906108c SS |
3657 | @section Information about a frame |
3658 | ||
3659 | There are several other commands to print information about the selected | |
3660 | stack frame. | |
3661 | ||
3662 | @table @code | |
3663 | @item frame | |
3664 | @itemx f | |
3665 | When used without any argument, this command does not change which | |
3666 | frame is selected, but prints a brief description of the currently | |
3667 | selected stack frame. It can be abbreviated @code{f}. With an | |
3668 | argument, this command is used to select a stack frame. | |
3669 | @xref{Selection, ,Selecting a frame}. | |
3670 | ||
3671 | @kindex info frame | |
3672 | @kindex info f | |
3673 | @item info frame | |
3674 | @itemx info f | |
3675 | This command prints a verbose description of the selected stack frame, | |
3676 | including: | |
3677 | ||
3678 | @itemize @bullet | |
3679 | @item | |
3680 | the address of the frame | |
3681 | @item | |
3682 | the address of the next frame down (called by this frame) | |
3683 | @item | |
3684 | the address of the next frame up (caller of this frame) | |
3685 | @item | |
3686 | the language in which the source code corresponding to this frame is written | |
3687 | @item | |
3688 | the address of the frame's arguments | |
3689 | @item | |
d4f3574e SS |
3690 | the address of the frame's local variables |
3691 | @item | |
c906108c SS |
3692 | the program counter saved in it (the address of execution in the caller frame) |
3693 | @item | |
3694 | which registers were saved in the frame | |
3695 | @end itemize | |
3696 | ||
3697 | @noindent The verbose description is useful when | |
3698 | something has gone wrong that has made the stack format fail to fit | |
3699 | the usual conventions. | |
3700 | ||
3701 | @item info frame @var{addr} | |
3702 | @itemx info f @var{addr} | |
3703 | Print a verbose description of the frame at address @var{addr}, without | |
3704 | selecting that frame. The selected frame remains unchanged by this | |
3705 | command. This requires the same kind of address (more than one for some | |
3706 | architectures) that you specify in the @code{frame} command. | |
3707 | @xref{Selection, ,Selecting a frame}. | |
3708 | ||
3709 | @kindex info args | |
3710 | @item info args | |
3711 | Print the arguments of the selected frame, each on a separate line. | |
3712 | ||
3713 | @item info locals | |
3714 | @kindex info locals | |
3715 | Print the local variables of the selected frame, each on a separate | |
3716 | line. These are all variables (declared either static or automatic) | |
3717 | accessible at the point of execution of the selected frame. | |
3718 | ||
c906108c | 3719 | @kindex info catch |
d4f3574e SS |
3720 | @cindex catch exceptions, list active handlers |
3721 | @cindex exception handlers, how to list | |
c906108c SS |
3722 | @item info catch |
3723 | Print a list of all the exception handlers that are active in the | |
3724 | current stack frame at the current point of execution. To see other | |
3725 | exception handlers, visit the associated frame (using the @code{up}, | |
3726 | @code{down}, or @code{frame} commands); then type @code{info catch}. | |
3727 | @xref{Set Catchpoints, , Setting catchpoints}. | |
53a5351d | 3728 | |
c906108c SS |
3729 | @end table |
3730 | ||
c906108c | 3731 | |
53a5351d | 3732 | @node Source |
c906108c SS |
3733 | @chapter Examining Source Files |
3734 | ||
3735 | @value{GDBN} can print parts of your program's source, since the debugging | |
3736 | information recorded in the program tells @value{GDBN} what source files were | |
3737 | used to build it. When your program stops, @value{GDBN} spontaneously prints | |
3738 | the line where it stopped. Likewise, when you select a stack frame | |
3739 | (@pxref{Selection, ,Selecting a frame}), @value{GDBN} prints the line where | |
3740 | execution in that frame has stopped. You can print other portions of | |
3741 | source files by explicit command. | |
3742 | ||
7a292a7a | 3743 | If you use @value{GDBN} through its @sc{gnu} Emacs interface, you may |
d4f3574e | 3744 | prefer to use Emacs facilities to view source; see @ref{Emacs, ,Using |
7a292a7a | 3745 | @value{GDBN} under @sc{gnu} Emacs}. |
c906108c SS |
3746 | |
3747 | @menu | |
3748 | * List:: Printing source lines | |
c906108c | 3749 | * Search:: Searching source files |
c906108c SS |
3750 | * Source Path:: Specifying source directories |
3751 | * Machine Code:: Source and machine code | |
3752 | @end menu | |
3753 | ||
53a5351d | 3754 | @node List |
c906108c SS |
3755 | @section Printing source lines |
3756 | ||
3757 | @kindex list | |
3758 | @kindex l | |
3759 | To print lines from a source file, use the @code{list} command | |
3760 | (abbreviated @code{l}). By default, ten lines are printed. | |
3761 | There are several ways to specify what part of the file you want to print. | |
3762 | ||
3763 | Here are the forms of the @code{list} command most commonly used: | |
3764 | ||
3765 | @table @code | |
3766 | @item list @var{linenum} | |
3767 | Print lines centered around line number @var{linenum} in the | |
3768 | current source file. | |
3769 | ||
3770 | @item list @var{function} | |
3771 | Print lines centered around the beginning of function | |
3772 | @var{function}. | |
3773 | ||
3774 | @item list | |
3775 | Print more lines. If the last lines printed were printed with a | |
3776 | @code{list} command, this prints lines following the last lines | |
3777 | printed; however, if the last line printed was a solitary line printed | |
3778 | as part of displaying a stack frame (@pxref{Stack, ,Examining the | |
3779 | Stack}), this prints lines centered around that line. | |
3780 | ||
3781 | @item list - | |
3782 | Print lines just before the lines last printed. | |
3783 | @end table | |
3784 | ||
3785 | By default, @value{GDBN} prints ten source lines with any of these forms of | |
3786 | the @code{list} command. You can change this using @code{set listsize}: | |
3787 | ||
3788 | @table @code | |
3789 | @kindex set listsize | |
3790 | @item set listsize @var{count} | |
3791 | Make the @code{list} command display @var{count} source lines (unless | |
3792 | the @code{list} argument explicitly specifies some other number). | |
3793 | ||
3794 | @kindex show listsize | |
3795 | @item show listsize | |
3796 | Display the number of lines that @code{list} prints. | |
3797 | @end table | |
3798 | ||
3799 | Repeating a @code{list} command with @key{RET} discards the argument, | |
3800 | so it is equivalent to typing just @code{list}. This is more useful | |
3801 | than listing the same lines again. An exception is made for an | |
3802 | argument of @samp{-}; that argument is preserved in repetition so that | |
3803 | each repetition moves up in the source file. | |
3804 | ||
3805 | @cindex linespec | |
3806 | In general, the @code{list} command expects you to supply zero, one or two | |
3807 | @dfn{linespecs}. Linespecs specify source lines; there are several ways | |
d4f3574e | 3808 | of writing them, but the effect is always to specify some source line. |
c906108c SS |
3809 | Here is a complete description of the possible arguments for @code{list}: |
3810 | ||
3811 | @table @code | |
3812 | @item list @var{linespec} | |
3813 | Print lines centered around the line specified by @var{linespec}. | |
3814 | ||
3815 | @item list @var{first},@var{last} | |
3816 | Print lines from @var{first} to @var{last}. Both arguments are | |
3817 | linespecs. | |
3818 | ||
3819 | @item list ,@var{last} | |
3820 | Print lines ending with @var{last}. | |
3821 | ||
3822 | @item list @var{first}, | |
3823 | Print lines starting with @var{first}. | |
3824 | ||
3825 | @item list + | |
3826 | Print lines just after the lines last printed. | |
3827 | ||
3828 | @item list - | |
3829 | Print lines just before the lines last printed. | |
3830 | ||
3831 | @item list | |
3832 | As described in the preceding table. | |
3833 | @end table | |
3834 | ||
3835 | Here are the ways of specifying a single source line---all the | |
3836 | kinds of linespec. | |
3837 | ||
3838 | @table @code | |
3839 | @item @var{number} | |
3840 | Specifies line @var{number} of the current source file. | |
3841 | When a @code{list} command has two linespecs, this refers to | |
3842 | the same source file as the first linespec. | |
3843 | ||
3844 | @item +@var{offset} | |
3845 | Specifies the line @var{offset} lines after the last line printed. | |
3846 | When used as the second linespec in a @code{list} command that has | |
3847 | two, this specifies the line @var{offset} lines down from the | |
3848 | first linespec. | |
3849 | ||
3850 | @item -@var{offset} | |
3851 | Specifies the line @var{offset} lines before the last line printed. | |
3852 | ||
3853 | @item @var{filename}:@var{number} | |
3854 | Specifies line @var{number} in the source file @var{filename}. | |
3855 | ||
3856 | @item @var{function} | |
3857 | Specifies the line that begins the body of the function @var{function}. | |
3858 | For example: in C, this is the line with the open brace. | |
3859 | ||
3860 | @item @var{filename}:@var{function} | |
3861 | Specifies the line of the open-brace that begins the body of the | |
3862 | function @var{function} in the file @var{filename}. You only need the | |
3863 | file name with a function name to avoid ambiguity when there are | |
3864 | identically named functions in different source files. | |
3865 | ||
3866 | @item *@var{address} | |
3867 | Specifies the line containing the program address @var{address}. | |
3868 | @var{address} may be any expression. | |
3869 | @end table | |
3870 | ||
53a5351d | 3871 | @node Search |
c906108c SS |
3872 | @section Searching source files |
3873 | @cindex searching | |
3874 | @kindex reverse-search | |
3875 | ||
3876 | There are two commands for searching through the current source file for a | |
3877 | regular expression. | |
3878 | ||
3879 | @table @code | |
3880 | @kindex search | |
3881 | @kindex forward-search | |
3882 | @item forward-search @var{regexp} | |
3883 | @itemx search @var{regexp} | |
3884 | The command @samp{forward-search @var{regexp}} checks each line, | |
3885 | starting with the one following the last line listed, for a match for | |
3886 | @var{regexp}. It lists the line that is found. You can use the | |
3887 | synonym @samp{search @var{regexp}} or abbreviate the command name as | |
3888 | @code{fo}. | |
3889 | ||
3890 | @item reverse-search @var{regexp} | |
3891 | The command @samp{reverse-search @var{regexp}} checks each line, starting | |
3892 | with the one before the last line listed and going backward, for a match | |
3893 | for @var{regexp}. It lists the line that is found. You can abbreviate | |
3894 | this command as @code{rev}. | |
3895 | @end table | |
c906108c | 3896 | |
53a5351d | 3897 | @node Source Path |
c906108c SS |
3898 | @section Specifying source directories |
3899 | ||
3900 | @cindex source path | |
3901 | @cindex directories for source files | |
3902 | Executable programs sometimes do not record the directories of the source | |
3903 | files from which they were compiled, just the names. Even when they do, | |
3904 | the directories could be moved between the compilation and your debugging | |
3905 | session. @value{GDBN} has a list of directories to search for source files; | |
3906 | this is called the @dfn{source path}. Each time @value{GDBN} wants a source file, | |
3907 | it tries all the directories in the list, in the order they are present | |
3908 | in the list, until it finds a file with the desired name. Note that | |
3909 | the executable search path is @emph{not} used for this purpose. Neither is | |
3910 | the current working directory, unless it happens to be in the source | |
3911 | path. | |
3912 | ||
3913 | If @value{GDBN} cannot find a source file in the source path, and the | |
3914 | object program records a directory, @value{GDBN} tries that directory | |
3915 | too. If the source path is empty, and there is no record of the | |
3916 | compilation directory, @value{GDBN} looks in the current directory as a | |
3917 | last resort. | |
3918 | ||
3919 | Whenever you reset or rearrange the source path, @value{GDBN} clears out | |
3920 | any information it has cached about where source files are found and where | |
3921 | each line is in the file. | |
3922 | ||
3923 | @kindex directory | |
3924 | @kindex dir | |
d4f3574e SS |
3925 | When you start @value{GDBN}, its source path includes only @samp{cdir} |
3926 | and @samp{cwd}, in that order. | |
c906108c SS |
3927 | To add other directories, use the @code{directory} command. |
3928 | ||
3929 | @table @code | |
3930 | @item directory @var{dirname} @dots{} | |
3931 | @item dir @var{dirname} @dots{} | |
3932 | Add directory @var{dirname} to the front of the source path. Several | |
d4f3574e SS |
3933 | directory names may be given to this command, separated by @samp{:} |
3934 | (@samp{;} on MS-DOS and MS-Windows, where @samp{:} usually appears as | |
3935 | part of absolute file names) or | |
c906108c SS |
3936 | whitespace. You may specify a directory that is already in the source |
3937 | path; this moves it forward, so @value{GDBN} searches it sooner. | |
3938 | ||
3939 | @kindex cdir | |
3940 | @kindex cwd | |
3941 | @kindex $cdir | |
3942 | @kindex $cwd | |
3943 | @cindex compilation directory | |
3944 | @cindex current directory | |
3945 | @cindex working directory | |
3946 | @cindex directory, current | |
3947 | @cindex directory, compilation | |
3948 | You can use the string @samp{$cdir} to refer to the compilation | |
3949 | directory (if one is recorded), and @samp{$cwd} to refer to the current | |
3950 | working directory. @samp{$cwd} is not the same as @samp{.}---the former | |
3951 | tracks the current working directory as it changes during your @value{GDBN} | |
3952 | session, while the latter is immediately expanded to the current | |
3953 | directory at the time you add an entry to the source path. | |
3954 | ||
3955 | @item directory | |
3956 | Reset the source path to empty again. This requires confirmation. | |
3957 | ||
3958 | @c RET-repeat for @code{directory} is explicitly disabled, but since | |
3959 | @c repeating it would be a no-op we do not say that. (thanks to RMS) | |
3960 | ||
3961 | @item show directories | |
3962 | @kindex show directories | |
3963 | Print the source path: show which directories it contains. | |
3964 | @end table | |
3965 | ||
3966 | If your source path is cluttered with directories that are no longer of | |
3967 | interest, @value{GDBN} may sometimes cause confusion by finding the wrong | |
3968 | versions of source. You can correct the situation as follows: | |
3969 | ||
3970 | @enumerate | |
3971 | @item | |
3972 | Use @code{directory} with no argument to reset the source path to empty. | |
3973 | ||
3974 | @item | |
3975 | Use @code{directory} with suitable arguments to reinstall the | |
3976 | directories you want in the source path. You can add all the | |
3977 | directories in one command. | |
3978 | @end enumerate | |
3979 | ||
53a5351d | 3980 | @node Machine Code |
c906108c SS |
3981 | @section Source and machine code |
3982 | ||
3983 | You can use the command @code{info line} to map source lines to program | |
3984 | addresses (and vice versa), and the command @code{disassemble} to display | |
3985 | a range of addresses as machine instructions. When run under @sc{gnu} Emacs | |
d4f3574e | 3986 | mode, the @code{info line} command causes the arrow to point to the |
c906108c SS |
3987 | line specified. Also, @code{info line} prints addresses in symbolic form as |
3988 | well as hex. | |
3989 | ||
3990 | @table @code | |
3991 | @kindex info line | |
3992 | @item info line @var{linespec} | |
3993 | Print the starting and ending addresses of the compiled code for | |
3994 | source line @var{linespec}. You can specify source lines in any of | |
3995 | the ways understood by the @code{list} command (@pxref{List, ,Printing | |
3996 | source lines}). | |
3997 | @end table | |
3998 | ||
3999 | For example, we can use @code{info line} to discover the location of | |
4000 | the object code for the first line of function | |
4001 | @code{m4_changequote}: | |
4002 | ||
d4f3574e SS |
4003 | @c FIXME: I think this example should also show the addresses in |
4004 | @c symbolic form, as they usually would be displayed. | |
c906108c SS |
4005 | @smallexample |
4006 | (@value{GDBP}) info line m4_changecom | |
4007 | Line 895 of "builtin.c" starts at pc 0x634c and ends at 0x6350. | |
4008 | @end smallexample | |
4009 | ||
4010 | @noindent | |
4011 | We can also inquire (using @code{*@var{addr}} as the form for | |
4012 | @var{linespec}) what source line covers a particular address: | |
4013 | @smallexample | |
4014 | (@value{GDBP}) info line *0x63ff | |
4015 | Line 926 of "builtin.c" starts at pc 0x63e4 and ends at 0x6404. | |
4016 | @end smallexample | |
4017 | ||
4018 | @cindex @code{$_} and @code{info line} | |
d4f3574e | 4019 | @kindex x@r{, and }@code{info line} |
c906108c SS |
4020 | After @code{info line}, the default address for the @code{x} command |
4021 | is changed to the starting address of the line, so that @samp{x/i} is | |
4022 | sufficient to begin examining the machine code (@pxref{Memory, | |
4023 | ,Examining memory}). Also, this address is saved as the value of the | |
4024 | convenience variable @code{$_} (@pxref{Convenience Vars, ,Convenience | |
4025 | variables}). | |
4026 | ||
4027 | @table @code | |
4028 | @kindex disassemble | |
4029 | @cindex assembly instructions | |
4030 | @cindex instructions, assembly | |
4031 | @cindex machine instructions | |
4032 | @cindex listing machine instructions | |
4033 | @item disassemble | |
4034 | This specialized command dumps a range of memory as machine | |
4035 | instructions. The default memory range is the function surrounding the | |
4036 | program counter of the selected frame. A single argument to this | |
4037 | command is a program counter value; @value{GDBN} dumps the function | |
4038 | surrounding this value. Two arguments specify a range of addresses | |
4039 | (first inclusive, second exclusive) to dump. | |
4040 | @end table | |
4041 | ||
c906108c SS |
4042 | The following example shows the disassembly of a range of addresses of |
4043 | HP PA-RISC 2.0 code: | |
4044 | ||
4045 | @smallexample | |
4046 | (@value{GDBP}) disas 0x32c4 0x32e4 | |
4047 | Dump of assembler code from 0x32c4 to 0x32e4: | |
4048 | 0x32c4 <main+204>: addil 0,dp | |
4049 | 0x32c8 <main+208>: ldw 0x22c(sr0,r1),r26 | |
4050 | 0x32cc <main+212>: ldil 0x3000,r31 | |
4051 | 0x32d0 <main+216>: ble 0x3f8(sr4,r31) | |
4052 | 0x32d4 <main+220>: ldo 0(r31),rp | |
4053 | 0x32d8 <main+224>: addil -0x800,dp | |
4054 | 0x32dc <main+228>: ldo 0x588(r1),r26 | |
4055 | 0x32e0 <main+232>: ldil 0x3000,r31 | |
4056 | End of assembler dump. | |
4057 | @end smallexample | |
c906108c SS |
4058 | |
4059 | Some architectures have more than one commonly-used set of instruction | |
4060 | mnemonics or other syntax. | |
4061 | ||
4062 | @table @code | |
d4f3574e | 4063 | @kindex set disassembly-flavor |
c906108c SS |
4064 | @cindex assembly instructions |
4065 | @cindex instructions, assembly | |
4066 | @cindex machine instructions | |
4067 | @cindex listing machine instructions | |
d4f3574e SS |
4068 | @cindex Intel disassembly flavor |
4069 | @cindex AT&T disassembly flavor | |
4070 | @item set disassembly-flavor @var{instruction-set} | |
c906108c SS |
4071 | Select the instruction set to use when disassembling the |
4072 | program via the @code{disassemble} or @code{x/i} commands. | |
4073 | ||
4074 | Currently this command is only defined for the Intel x86 family. You | |
d4f3574e SS |
4075 | can set @var{instruction-set} to either @code{intel} or @code{att}. |
4076 | The default is @code{att}, the AT&T flavor used by default by Unix | |
4077 | assemblers for x86-based targets. | |
c906108c SS |
4078 | @end table |
4079 | ||
4080 | ||
53a5351d | 4081 | @node Data |
c906108c SS |
4082 | @chapter Examining Data |
4083 | ||
4084 | @cindex printing data | |
4085 | @cindex examining data | |
4086 | @kindex print | |
4087 | @kindex inspect | |
4088 | @c "inspect" is not quite a synonym if you are using Epoch, which we do not | |
4089 | @c document because it is nonstandard... Under Epoch it displays in a | |
4090 | @c different window or something like that. | |
4091 | The usual way to examine data in your program is with the @code{print} | |
7a292a7a SS |
4092 | command (abbreviated @code{p}), or its synonym @code{inspect}. It |
4093 | evaluates and prints the value of an expression of the language your | |
4094 | program is written in (@pxref{Languages, ,Using @value{GDBN} with | |
4095 | Different Languages}). | |
c906108c SS |
4096 | |
4097 | @table @code | |
d4f3574e SS |
4098 | @item print @var{expr} |
4099 | @itemx print /@var{f} @var{expr} | |
4100 | @var{expr} is an expression (in the source language). By default the | |
4101 | value of @var{expr} is printed in a format appropriate to its data type; | |
c906108c | 4102 | you can choose a different format by specifying @samp{/@var{f}}, where |
d4f3574e | 4103 | @var{f} is a letter specifying the format; see @ref{Output Formats,,Output |
c906108c SS |
4104 | formats}. |
4105 | ||
4106 | @item print | |
4107 | @itemx print /@var{f} | |
d4f3574e | 4108 | If you omit @var{expr}, @value{GDBN} displays the last value again (from the |
c906108c SS |
4109 | @dfn{value history}; @pxref{Value History, ,Value history}). This allows you to |
4110 | conveniently inspect the same value in an alternative format. | |
4111 | @end table | |
4112 | ||
4113 | A more low-level way of examining data is with the @code{x} command. | |
4114 | It examines data in memory at a specified address and prints it in a | |
4115 | specified format. @xref{Memory, ,Examining memory}. | |
4116 | ||
7a292a7a | 4117 | If you are interested in information about types, or about how the |
d4f3574e SS |
4118 | fields of a struct or a class are declared, use the @code{ptype @var{exp}} |
4119 | command rather than @code{print}. @xref{Symbols, ,Examining the Symbol | |
7a292a7a | 4120 | Table}. |
c906108c SS |
4121 | |
4122 | @menu | |
4123 | * Expressions:: Expressions | |
4124 | * Variables:: Program variables | |
4125 | * Arrays:: Artificial arrays | |
4126 | * Output Formats:: Output formats | |
4127 | * Memory:: Examining memory | |
4128 | * Auto Display:: Automatic display | |
4129 | * Print Settings:: Print settings | |
4130 | * Value History:: Value history | |
4131 | * Convenience Vars:: Convenience variables | |
4132 | * Registers:: Registers | |
c906108c | 4133 | * Floating Point Hardware:: Floating point hardware |
c906108c SS |
4134 | @end menu |
4135 | ||
53a5351d | 4136 | @node Expressions |
c906108c SS |
4137 | @section Expressions |
4138 | ||
4139 | @cindex expressions | |
4140 | @code{print} and many other @value{GDBN} commands accept an expression and | |
4141 | compute its value. Any kind of constant, variable or operator defined | |
4142 | by the programming language you are using is valid in an expression in | |
4143 | @value{GDBN}. This includes conditional expressions, function calls, casts | |
4144 | and string constants. It unfortunately does not include symbols defined | |
4145 | by preprocessor @code{#define} commands. | |
4146 | ||
d4f3574e SS |
4147 | @value{GDBN} supports array constants in expressions input by |
4148 | the user. The syntax is @{@var{element}, @var{element}@dots{}@}. For example, | |
4149 | you can use the command @code{print @{1, 2, 3@}} to build up an array in | |
4150 | memory that is @code{malloc}ed in the target program. | |
c906108c | 4151 | |
c906108c SS |
4152 | Because C is so widespread, most of the expressions shown in examples in |
4153 | this manual are in C. @xref{Languages, , Using @value{GDBN} with Different | |
4154 | Languages}, for information on how to use expressions in other | |
4155 | languages. | |
4156 | ||
4157 | In this section, we discuss operators that you can use in @value{GDBN} | |
4158 | expressions regardless of your programming language. | |
4159 | ||
4160 | Casts are supported in all languages, not just in C, because it is so | |
4161 | useful to cast a number into a pointer in order to examine a structure | |
4162 | at that address in memory. | |
4163 | @c FIXME: casts supported---Mod2 true? | |
c906108c SS |
4164 | |
4165 | @value{GDBN} supports these operators, in addition to those common | |
4166 | to programming languages: | |
4167 | ||
4168 | @table @code | |
4169 | @item @@ | |
4170 | @samp{@@} is a binary operator for treating parts of memory as arrays. | |
4171 | @xref{Arrays, ,Artificial arrays}, for more information. | |
4172 | ||
4173 | @item :: | |
4174 | @samp{::} allows you to specify a variable in terms of the file or | |
4175 | function where it is defined. @xref{Variables, ,Program variables}. | |
4176 | ||
4177 | @cindex @{@var{type}@} | |
4178 | @cindex type casting memory | |
4179 | @cindex memory, viewing as typed object | |
4180 | @cindex casts, to view memory | |
4181 | @item @{@var{type}@} @var{addr} | |
4182 | Refers to an object of type @var{type} stored at address @var{addr} in | |
4183 | memory. @var{addr} may be any expression whose value is an integer or | |
4184 | pointer (but parentheses are required around binary operators, just as in | |
4185 | a cast). This construct is allowed regardless of what kind of data is | |
4186 | normally supposed to reside at @var{addr}. | |
4187 | @end table | |
4188 | ||
53a5351d | 4189 | @node Variables |
c906108c SS |
4190 | @section Program variables |
4191 | ||
4192 | The most common kind of expression to use is the name of a variable | |
4193 | in your program. | |
4194 | ||
4195 | Variables in expressions are understood in the selected stack frame | |
4196 | (@pxref{Selection, ,Selecting a frame}); they must be either: | |
4197 | ||
4198 | @itemize @bullet | |
4199 | @item | |
4200 | global (or file-static) | |
4201 | @end itemize | |
4202 | ||
4203 | @noindent or | |
4204 | ||
4205 | @itemize @bullet | |
4206 | @item | |
4207 | visible according to the scope rules of the | |
4208 | programming language from the point of execution in that frame | |
4209 | @end itemize | |
4210 | ||
4211 | @noindent This means that in the function | |
4212 | ||
4213 | @example | |
4214 | foo (a) | |
4215 | int a; | |
4216 | @{ | |
4217 | bar (a); | |
4218 | @{ | |
4219 | int b = test (); | |
4220 | bar (b); | |
4221 | @} | |
4222 | @} | |
4223 | @end example | |
4224 | ||
4225 | @noindent | |
4226 | you can examine and use the variable @code{a} whenever your program is | |
4227 | executing within the function @code{foo}, but you can only use or | |
4228 | examine the variable @code{b} while your program is executing inside | |
4229 | the block where @code{b} is declared. | |
4230 | ||
4231 | @cindex variable name conflict | |
4232 | There is an exception: you can refer to a variable or function whose | |
4233 | scope is a single source file even if the current execution point is not | |
4234 | in this file. But it is possible to have more than one such variable or | |
4235 | function with the same name (in different source files). If that | |
4236 | happens, referring to that name has unpredictable effects. If you wish, | |
4237 | you can specify a static variable in a particular function or file, | |
4238 | using the colon-colon notation: | |
4239 | ||
d4f3574e | 4240 | @cindex colon-colon, context for variables/functions |
c906108c SS |
4241 | @iftex |
4242 | @c info cannot cope with a :: index entry, but why deprive hard copy readers? | |
4243 | @kindex :: | |
4244 | @end iftex | |
4245 | @example | |
4246 | @var{file}::@var{variable} | |
4247 | @var{function}::@var{variable} | |
4248 | @end example | |
4249 | ||
4250 | @noindent | |
4251 | Here @var{file} or @var{function} is the name of the context for the | |
4252 | static @var{variable}. In the case of file names, you can use quotes to | |
4253 | make sure @value{GDBN} parses the file name as a single word---for example, | |
4254 | to print a global value of @code{x} defined in @file{f2.c}: | |
4255 | ||
4256 | @example | |
4257 | (@value{GDBP}) p 'f2.c'::x | |
4258 | @end example | |
4259 | ||
c906108c SS |
4260 | @cindex C++ scope resolution |
4261 | This use of @samp{::} is very rarely in conflict with the very similar | |
4262 | use of the same notation in C++. @value{GDBN} also supports use of the C++ | |
4263 | scope resolution operator in @value{GDBN} expressions. | |
4264 | @c FIXME: Um, so what happens in one of those rare cases where it's in | |
4265 | @c conflict?? --mew | |
c906108c SS |
4266 | |
4267 | @cindex wrong values | |
4268 | @cindex variable values, wrong | |
4269 | @quotation | |
4270 | @emph{Warning:} Occasionally, a local variable may appear to have the | |
4271 | wrong value at certain points in a function---just after entry to a new | |
4272 | scope, and just before exit. | |
4273 | @end quotation | |
4274 | You may see this problem when you are stepping by machine instructions. | |
4275 | This is because, on most machines, it takes more than one instruction to | |
4276 | set up a stack frame (including local variable definitions); if you are | |
4277 | stepping by machine instructions, variables may appear to have the wrong | |
4278 | values until the stack frame is completely built. On exit, it usually | |
4279 | also takes more than one machine instruction to destroy a stack frame; | |
4280 | after you begin stepping through that group of instructions, local | |
4281 | variable definitions may be gone. | |
4282 | ||
4283 | This may also happen when the compiler does significant optimizations. | |
4284 | To be sure of always seeing accurate values, turn off all optimization | |
4285 | when compiling. | |
4286 | ||
d4f3574e SS |
4287 | @cindex ``No symbol "foo" in current context'' |
4288 | Another possible effect of compiler optimizations is to optimize | |
4289 | unused variables out of existence, or assign variables to registers (as | |
4290 | opposed to memory addresses). Depending on the support for such cases | |
4291 | offered by the debug info format used by the compiler, @value{GDBN} | |
4292 | might not be able to display values for such local variables. If that | |
4293 | happens, @value{GDBN} will print a message like this: | |
4294 | ||
4295 | @example | |
4296 | No symbol "foo" in current context. | |
4297 | @end example | |
4298 | ||
4299 | To solve such problems, either recompile without optimizations, or use a | |
4300 | different debug info format, if the compiler supports several such | |
4301 | formats. For example, @value{NGCC}, the @sc{gnu} C/C++ compiler usually | |
4302 | supports the @samp{-gstabs} option. @samp{-gstabs} produces debug info | |
4303 | in a format that is superior to formats such as COFF. You may be able | |
4304 | to use DWARF-2 (@samp{-gdwarf-2}), which is also an effective form for | |
4305 | debug info. See @ref{Debugging Options,,Options for Debugging Your | |
4306 | Program or @sc{gnu} CC, gcc.info, Using @sc{gnu} CC}, for more | |
4307 | information. | |
4308 | ||
4309 | ||
53a5351d | 4310 | @node Arrays |
c906108c SS |
4311 | @section Artificial arrays |
4312 | ||
4313 | @cindex artificial array | |
4314 | @kindex @@ | |
4315 | It is often useful to print out several successive objects of the | |
4316 | same type in memory; a section of an array, or an array of | |
4317 | dynamically determined size for which only a pointer exists in the | |
4318 | program. | |
4319 | ||
4320 | You can do this by referring to a contiguous span of memory as an | |
4321 | @dfn{artificial array}, using the binary operator @samp{@@}. The left | |
4322 | operand of @samp{@@} should be the first element of the desired array | |
4323 | and be an individual object. The right operand should be the desired length | |
4324 | of the array. The result is an array value whose elements are all of | |
4325 | the type of the left argument. The first element is actually the left | |
4326 | argument; the second element comes from bytes of memory immediately | |
4327 | following those that hold the first element, and so on. Here is an | |
4328 | example. If a program says | |
4329 | ||
4330 | @example | |
4331 | int *array = (int *) malloc (len * sizeof (int)); | |
4332 | @end example | |
4333 | ||
4334 | @noindent | |
4335 | you can print the contents of @code{array} with | |
4336 | ||
4337 | @example | |
4338 | p *array@@len | |
4339 | @end example | |
4340 | ||
4341 | The left operand of @samp{@@} must reside in memory. Array values made | |
4342 | with @samp{@@} in this way behave just like other arrays in terms of | |
4343 | subscripting, and are coerced to pointers when used in expressions. | |
4344 | Artificial arrays most often appear in expressions via the value history | |
4345 | (@pxref{Value History, ,Value history}), after printing one out. | |
4346 | ||
4347 | Another way to create an artificial array is to use a cast. | |
4348 | This re-interprets a value as if it were an array. | |
4349 | The value need not be in memory: | |
4350 | @example | |
4351 | (@value{GDBP}) p/x (short[2])0x12345678 | |
4352 | $1 = @{0x1234, 0x5678@} | |
4353 | @end example | |
4354 | ||
4355 | As a convenience, if you leave the array length out (as in | |
c3f6f71d | 4356 | @samp{(@var{type}[])@var{value}}) @value{GDBN} calculates the size to fill |
c906108c SS |
4357 | the value (as @samp{sizeof(@var{value})/sizeof(@var{type})}: |
4358 | @example | |
4359 | (@value{GDBP}) p/x (short[])0x12345678 | |
4360 | $2 = @{0x1234, 0x5678@} | |
4361 | @end example | |
4362 | ||
4363 | Sometimes the artificial array mechanism is not quite enough; in | |
4364 | moderately complex data structures, the elements of interest may not | |
4365 | actually be adjacent---for example, if you are interested in the values | |
4366 | of pointers in an array. One useful work-around in this situation is | |
4367 | to use a convenience variable (@pxref{Convenience Vars, ,Convenience | |
4368 | variables}) as a counter in an expression that prints the first | |
4369 | interesting value, and then repeat that expression via @key{RET}. For | |
4370 | instance, suppose you have an array @code{dtab} of pointers to | |
4371 | structures, and you are interested in the values of a field @code{fv} | |
4372 | in each structure. Here is an example of what you might type: | |
4373 | ||
4374 | @example | |
4375 | set $i = 0 | |
4376 | p dtab[$i++]->fv | |
4377 | @key{RET} | |
4378 | @key{RET} | |
4379 | @dots{} | |
4380 | @end example | |
4381 | ||
53a5351d | 4382 | @node Output Formats |
c906108c SS |
4383 | @section Output formats |
4384 | ||
4385 | @cindex formatted output | |
4386 | @cindex output formats | |
4387 | By default, @value{GDBN} prints a value according to its data type. Sometimes | |
4388 | this is not what you want. For example, you might want to print a number | |
4389 | in hex, or a pointer in decimal. Or you might want to view data in memory | |
4390 | at a certain address as a character string or as an instruction. To do | |
4391 | these things, specify an @dfn{output format} when you print a value. | |
4392 | ||
4393 | The simplest use of output formats is to say how to print a value | |
4394 | already computed. This is done by starting the arguments of the | |
4395 | @code{print} command with a slash and a format letter. The format | |
4396 | letters supported are: | |
4397 | ||
4398 | @table @code | |
4399 | @item x | |
4400 | Regard the bits of the value as an integer, and print the integer in | |
4401 | hexadecimal. | |
4402 | ||
4403 | @item d | |
4404 | Print as integer in signed decimal. | |
4405 | ||
4406 | @item u | |
4407 | Print as integer in unsigned decimal. | |
4408 | ||
4409 | @item o | |
4410 | Print as integer in octal. | |
4411 | ||
4412 | @item t | |
4413 | Print as integer in binary. The letter @samp{t} stands for ``two''. | |
4414 | @footnote{@samp{b} cannot be used because these format letters are also | |
4415 | used with the @code{x} command, where @samp{b} stands for ``byte''; | |
d4f3574e | 4416 | see @ref{Memory,,Examining memory}.} |
c906108c SS |
4417 | |
4418 | @item a | |
4419 | @cindex unknown address, locating | |
4420 | Print as an address, both absolute in hexadecimal and as an offset from | |
4421 | the nearest preceding symbol. You can use this format used to discover | |
4422 | where (in what function) an unknown address is located: | |
4423 | ||
4424 | @example | |
4425 | (@value{GDBP}) p/a 0x54320 | |
4426 | $3 = 0x54320 <_initialize_vx+396> | |
4427 | @end example | |
4428 | ||
4429 | @item c | |
4430 | Regard as an integer and print it as a character constant. | |
4431 | ||
4432 | @item f | |
4433 | Regard the bits of the value as a floating point number and print | |
4434 | using typical floating point syntax. | |
4435 | @end table | |
4436 | ||
4437 | For example, to print the program counter in hex (@pxref{Registers}), type | |
4438 | ||
4439 | @example | |
4440 | p/x $pc | |
4441 | @end example | |
4442 | ||
4443 | @noindent | |
4444 | Note that no space is required before the slash; this is because command | |
4445 | names in @value{GDBN} cannot contain a slash. | |
4446 | ||
4447 | To reprint the last value in the value history with a different format, | |
4448 | you can use the @code{print} command with just a format and no | |
4449 | expression. For example, @samp{p/x} reprints the last value in hex. | |
4450 | ||
53a5351d | 4451 | @node Memory |
c906108c SS |
4452 | @section Examining memory |
4453 | ||
4454 | You can use the command @code{x} (for ``examine'') to examine memory in | |
4455 | any of several formats, independently of your program's data types. | |
4456 | ||
4457 | @cindex examining memory | |
4458 | @table @code | |
4459 | @kindex x | |
4460 | @item x/@var{nfu} @var{addr} | |
4461 | @itemx x @var{addr} | |
4462 | @itemx x | |
4463 | Use the @code{x} command to examine memory. | |
4464 | @end table | |
4465 | ||
4466 | @var{n}, @var{f}, and @var{u} are all optional parameters that specify how | |
4467 | much memory to display and how to format it; @var{addr} is an | |
4468 | expression giving the address where you want to start displaying memory. | |
4469 | If you use defaults for @var{nfu}, you need not type the slash @samp{/}. | |
4470 | Several commands set convenient defaults for @var{addr}. | |
4471 | ||
4472 | @table @r | |
4473 | @item @var{n}, the repeat count | |
4474 | The repeat count is a decimal integer; the default is 1. It specifies | |
4475 | how much memory (counting by units @var{u}) to display. | |
4476 | @c This really is **decimal**; unaffected by 'set radix' as of GDB | |
4477 | @c 4.1.2. | |
4478 | ||
4479 | @item @var{f}, the display format | |
4480 | The display format is one of the formats used by @code{print}, | |
4481 | @samp{s} (null-terminated string), or @samp{i} (machine instruction). | |
4482 | The default is @samp{x} (hexadecimal) initially. | |
4483 | The default changes each time you use either @code{x} or @code{print}. | |
4484 | ||
4485 | @item @var{u}, the unit size | |
4486 | The unit size is any of | |
4487 | ||
4488 | @table @code | |
4489 | @item b | |
4490 | Bytes. | |
4491 | @item h | |
4492 | Halfwords (two bytes). | |
4493 | @item w | |
4494 | Words (four bytes). This is the initial default. | |
4495 | @item g | |
4496 | Giant words (eight bytes). | |
4497 | @end table | |
4498 | ||
4499 | Each time you specify a unit size with @code{x}, that size becomes the | |
4500 | default unit the next time you use @code{x}. (For the @samp{s} and | |
4501 | @samp{i} formats, the unit size is ignored and is normally not written.) | |
4502 | ||
4503 | @item @var{addr}, starting display address | |
4504 | @var{addr} is the address where you want @value{GDBN} to begin displaying | |
4505 | memory. The expression need not have a pointer value (though it may); | |
4506 | it is always interpreted as an integer address of a byte of memory. | |
4507 | @xref{Expressions, ,Expressions}, for more information on expressions. The default for | |
4508 | @var{addr} is usually just after the last address examined---but several | |
4509 | other commands also set the default address: @code{info breakpoints} (to | |
4510 | the address of the last breakpoint listed), @code{info line} (to the | |
4511 | starting address of a line), and @code{print} (if you use it to display | |
4512 | a value from memory). | |
4513 | @end table | |
4514 | ||
4515 | For example, @samp{x/3uh 0x54320} is a request to display three halfwords | |
4516 | (@code{h}) of memory, formatted as unsigned decimal integers (@samp{u}), | |
4517 | starting at address @code{0x54320}. @samp{x/4xw $sp} prints the four | |
4518 | words (@samp{w}) of memory above the stack pointer (here, @samp{$sp}; | |
d4f3574e | 4519 | @pxref{Registers, ,Registers}) in hexadecimal (@samp{x}). |
c906108c SS |
4520 | |
4521 | Since the letters indicating unit sizes are all distinct from the | |
4522 | letters specifying output formats, you do not have to remember whether | |
4523 | unit size or format comes first; either order works. The output | |
4524 | specifications @samp{4xw} and @samp{4wx} mean exactly the same thing. | |
4525 | (However, the count @var{n} must come first; @samp{wx4} does not work.) | |
4526 | ||
4527 | Even though the unit size @var{u} is ignored for the formats @samp{s} | |
4528 | and @samp{i}, you might still want to use a count @var{n}; for example, | |
4529 | @samp{3i} specifies that you want to see three machine instructions, | |
4530 | including any operands. The command @code{disassemble} gives an | |
d4f3574e | 4531 | alternative way of inspecting machine instructions; see @ref{Machine |
c906108c SS |
4532 | Code,,Source and machine code}. |
4533 | ||
4534 | All the defaults for the arguments to @code{x} are designed to make it | |
4535 | easy to continue scanning memory with minimal specifications each time | |
4536 | you use @code{x}. For example, after you have inspected three machine | |
4537 | instructions with @samp{x/3i @var{addr}}, you can inspect the next seven | |
4538 | with just @samp{x/7}. If you use @key{RET} to repeat the @code{x} command, | |
4539 | the repeat count @var{n} is used again; the other arguments default as | |
4540 | for successive uses of @code{x}. | |
4541 | ||
4542 | @cindex @code{$_}, @code{$__}, and value history | |
4543 | The addresses and contents printed by the @code{x} command are not saved | |
4544 | in the value history because there is often too much of them and they | |
4545 | would get in the way. Instead, @value{GDBN} makes these values available for | |
4546 | subsequent use in expressions as values of the convenience variables | |
4547 | @code{$_} and @code{$__}. After an @code{x} command, the last address | |
4548 | examined is available for use in expressions in the convenience variable | |
4549 | @code{$_}. The contents of that address, as examined, are available in | |
4550 | the convenience variable @code{$__}. | |
4551 | ||
4552 | If the @code{x} command has a repeat count, the address and contents saved | |
4553 | are from the last memory unit printed; this is not the same as the last | |
4554 | address printed if several units were printed on the last line of output. | |
4555 | ||
53a5351d | 4556 | @node Auto Display |
c906108c SS |
4557 | @section Automatic display |
4558 | @cindex automatic display | |
4559 | @cindex display of expressions | |
4560 | ||
4561 | If you find that you want to print the value of an expression frequently | |
4562 | (to see how it changes), you might want to add it to the @dfn{automatic | |
4563 | display list} so that @value{GDBN} prints its value each time your program stops. | |
4564 | Each expression added to the list is given a number to identify it; | |
4565 | to remove an expression from the list, you specify that number. | |
4566 | The automatic display looks like this: | |
4567 | ||
4568 | @example | |
4569 | 2: foo = 38 | |
4570 | 3: bar[5] = (struct hack *) 0x3804 | |
4571 | @end example | |
4572 | ||
4573 | @noindent | |
4574 | This display shows item numbers, expressions and their current values. As with | |
4575 | displays you request manually using @code{x} or @code{print}, you can | |
4576 | specify the output format you prefer; in fact, @code{display} decides | |
4577 | whether to use @code{print} or @code{x} depending on how elaborate your | |
4578 | format specification is---it uses @code{x} if you specify a unit size, | |
4579 | or one of the two formats (@samp{i} and @samp{s}) that are only | |
4580 | supported by @code{x}; otherwise it uses @code{print}. | |
4581 | ||
4582 | @table @code | |
4583 | @kindex display | |
d4f3574e SS |
4584 | @item display @var{expr} |
4585 | Add the expression @var{expr} to the list of expressions to display | |
c906108c SS |
4586 | each time your program stops. @xref{Expressions, ,Expressions}. |
4587 | ||
4588 | @code{display} does not repeat if you press @key{RET} again after using it. | |
4589 | ||
d4f3574e | 4590 | @item display/@var{fmt} @var{expr} |
c906108c | 4591 | For @var{fmt} specifying only a display format and not a size or |
d4f3574e | 4592 | count, add the expression @var{expr} to the auto-display list but |
c906108c SS |
4593 | arrange to display it each time in the specified format @var{fmt}. |
4594 | @xref{Output Formats,,Output formats}. | |
4595 | ||
4596 | @item display/@var{fmt} @var{addr} | |
4597 | For @var{fmt} @samp{i} or @samp{s}, or including a unit-size or a | |
4598 | number of units, add the expression @var{addr} as a memory address to | |
4599 | be examined each time your program stops. Examining means in effect | |
4600 | doing @samp{x/@var{fmt} @var{addr}}. @xref{Memory, ,Examining memory}. | |
4601 | @end table | |
4602 | ||
4603 | For example, @samp{display/i $pc} can be helpful, to see the machine | |
4604 | instruction about to be executed each time execution stops (@samp{$pc} | |
d4f3574e | 4605 | is a common name for the program counter; @pxref{Registers, ,Registers}). |
c906108c SS |
4606 | |
4607 | @table @code | |
4608 | @kindex delete display | |
4609 | @kindex undisplay | |
4610 | @item undisplay @var{dnums}@dots{} | |
4611 | @itemx delete display @var{dnums}@dots{} | |
4612 | Remove item numbers @var{dnums} from the list of expressions to display. | |
4613 | ||
4614 | @code{undisplay} does not repeat if you press @key{RET} after using it. | |
4615 | (Otherwise you would just get the error @samp{No display number @dots{}}.) | |
4616 | ||
4617 | @kindex disable display | |
4618 | @item disable display @var{dnums}@dots{} | |
4619 | Disable the display of item numbers @var{dnums}. A disabled display | |
4620 | item is not printed automatically, but is not forgotten. It may be | |
4621 | enabled again later. | |
4622 | ||
4623 | @kindex enable display | |
4624 | @item enable display @var{dnums}@dots{} | |
4625 | Enable display of item numbers @var{dnums}. It becomes effective once | |
4626 | again in auto display of its expression, until you specify otherwise. | |
4627 | ||
4628 | @item display | |
4629 | Display the current values of the expressions on the list, just as is | |
4630 | done when your program stops. | |
4631 | ||
4632 | @kindex info display | |
4633 | @item info display | |
4634 | Print the list of expressions previously set up to display | |
4635 | automatically, each one with its item number, but without showing the | |
4636 | values. This includes disabled expressions, which are marked as such. | |
4637 | It also includes expressions which would not be displayed right now | |
4638 | because they refer to automatic variables not currently available. | |
4639 | @end table | |
4640 | ||
4641 | If a display expression refers to local variables, then it does not make | |
4642 | sense outside the lexical context for which it was set up. Such an | |
4643 | expression is disabled when execution enters a context where one of its | |
4644 | variables is not defined. For example, if you give the command | |
4645 | @code{display last_char} while inside a function with an argument | |
4646 | @code{last_char}, @value{GDBN} displays this argument while your program | |
4647 | continues to stop inside that function. When it stops elsewhere---where | |
4648 | there is no variable @code{last_char}---the display is disabled | |
4649 | automatically. The next time your program stops where @code{last_char} | |
4650 | is meaningful, you can enable the display expression once again. | |
4651 | ||
53a5351d | 4652 | @node Print Settings |
c906108c SS |
4653 | @section Print settings |
4654 | ||
4655 | @cindex format options | |
4656 | @cindex print settings | |
4657 | @value{GDBN} provides the following ways to control how arrays, structures, | |
4658 | and symbols are printed. | |
4659 | ||
4660 | @noindent | |
4661 | These settings are useful for debugging programs in any language: | |
4662 | ||
4663 | @table @code | |
4664 | @kindex set print address | |
4665 | @item set print address | |
4666 | @itemx set print address on | |
4667 | @value{GDBN} prints memory addresses showing the location of stack | |
4668 | traces, structure values, pointer values, breakpoints, and so forth, | |
4669 | even when it also displays the contents of those addresses. The default | |
4670 | is @code{on}. For example, this is what a stack frame display looks like with | |
4671 | @code{set print address on}: | |
4672 | ||
4673 | @smallexample | |
4674 | @group | |
4675 | (@value{GDBP}) f | |
4676 | #0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>") | |
4677 | at input.c:530 | |
4678 | 530 if (lquote != def_lquote) | |
4679 | @end group | |
4680 | @end smallexample | |
4681 | ||
4682 | @item set print address off | |
4683 | Do not print addresses when displaying their contents. For example, | |
4684 | this is the same stack frame displayed with @code{set print address off}: | |
4685 | ||
4686 | @smallexample | |
4687 | @group | |
4688 | (@value{GDBP}) set print addr off | |
4689 | (@value{GDBP}) f | |
4690 | #0 set_quotes (lq="<<", rq=">>") at input.c:530 | |
4691 | 530 if (lquote != def_lquote) | |
4692 | @end group | |
4693 | @end smallexample | |
4694 | ||
4695 | You can use @samp{set print address off} to eliminate all machine | |
4696 | dependent displays from the @value{GDBN} interface. For example, with | |
4697 | @code{print address off}, you should get the same text for backtraces on | |
4698 | all machines---whether or not they involve pointer arguments. | |
4699 | ||
4700 | @kindex show print address | |
4701 | @item show print address | |
4702 | Show whether or not addresses are to be printed. | |
4703 | @end table | |
4704 | ||
4705 | When @value{GDBN} prints a symbolic address, it normally prints the | |
4706 | closest earlier symbol plus an offset. If that symbol does not uniquely | |
4707 | identify the address (for example, it is a name whose scope is a single | |
4708 | source file), you may need to clarify. One way to do this is with | |
4709 | @code{info line}, for example @samp{info line *0x4537}. Alternately, | |
4710 | you can set @value{GDBN} to print the source file and line number when | |
4711 | it prints a symbolic address: | |
4712 | ||
4713 | @table @code | |
4714 | @kindex set print symbol-filename | |
4715 | @item set print symbol-filename on | |
4716 | Tell @value{GDBN} to print the source file name and line number of a | |
4717 | symbol in the symbolic form of an address. | |
4718 | ||
4719 | @item set print symbol-filename off | |
4720 | Do not print source file name and line number of a symbol. This is the | |
4721 | default. | |
4722 | ||
4723 | @kindex show print symbol-filename | |
4724 | @item show print symbol-filename | |
4725 | Show whether or not @value{GDBN} will print the source file name and | |
4726 | line number of a symbol in the symbolic form of an address. | |
4727 | @end table | |
4728 | ||
4729 | Another situation where it is helpful to show symbol filenames and line | |
4730 | numbers is when disassembling code; @value{GDBN} shows you the line | |
4731 | number and source file that corresponds to each instruction. | |
4732 | ||
4733 | Also, you may wish to see the symbolic form only if the address being | |
4734 | printed is reasonably close to the closest earlier symbol: | |
4735 | ||
4736 | @table @code | |
4737 | @kindex set print max-symbolic-offset | |
4738 | @item set print max-symbolic-offset @var{max-offset} | |
4739 | Tell @value{GDBN} to only display the symbolic form of an address if the | |
4740 | offset between the closest earlier symbol and the address is less than | |
4741 | @var{max-offset}. The default is 0, which tells @value{GDBN} | |
4742 | to always print the symbolic form of an address if any symbol precedes it. | |
4743 | ||
4744 | @kindex show print max-symbolic-offset | |
4745 | @item show print max-symbolic-offset | |
4746 | Ask how large the maximum offset is that @value{GDBN} prints in a | |
4747 | symbolic address. | |
4748 | @end table | |
4749 | ||
4750 | @cindex wild pointer, interpreting | |
4751 | @cindex pointer, finding referent | |
4752 | If you have a pointer and you are not sure where it points, try | |
4753 | @samp{set print symbol-filename on}. Then you can determine the name | |
4754 | and source file location of the variable where it points, using | |
4755 | @samp{p/a @var{pointer}}. This interprets the address in symbolic form. | |
4756 | For example, here @value{GDBN} shows that a variable @code{ptt} points | |
4757 | at another variable @code{t}, defined in @file{hi2.c}: | |
4758 | ||
4759 | @example | |
4760 | (@value{GDBP}) set print symbol-filename on | |
4761 | (@value{GDBP}) p/a ptt | |
4762 | $4 = 0xe008 <t in hi2.c> | |
4763 | @end example | |
4764 | ||
4765 | @quotation | |
4766 | @emph{Warning:} For pointers that point to a local variable, @samp{p/a} | |
4767 | does not show the symbol name and filename of the referent, even with | |
4768 | the appropriate @code{set print} options turned on. | |
4769 | @end quotation | |
4770 | ||
4771 | Other settings control how different kinds of objects are printed: | |
4772 | ||
4773 | @table @code | |
4774 | @kindex set print array | |
4775 | @item set print array | |
4776 | @itemx set print array on | |
4777 | Pretty print arrays. This format is more convenient to read, | |
4778 | but uses more space. The default is off. | |
4779 | ||
4780 | @item set print array off | |
4781 | Return to compressed format for arrays. | |
4782 | ||
4783 | @kindex show print array | |
4784 | @item show print array | |
4785 | Show whether compressed or pretty format is selected for displaying | |
4786 | arrays. | |
4787 | ||
4788 | @kindex set print elements | |
4789 | @item set print elements @var{number-of-elements} | |
4790 | Set a limit on how many elements of an array @value{GDBN} will print. | |
4791 | If @value{GDBN} is printing a large array, it stops printing after it has | |
4792 | printed the number of elements set by the @code{set print elements} command. | |
4793 | This limit also applies to the display of strings. | |
d4f3574e | 4794 | When @value{GDBN} starts, this limit is set to 200. |
c906108c SS |
4795 | Setting @var{number-of-elements} to zero means that the printing is unlimited. |
4796 | ||
4797 | @kindex show print elements | |
4798 | @item show print elements | |
4799 | Display the number of elements of a large array that @value{GDBN} will print. | |
4800 | If the number is 0, then the printing is unlimited. | |
4801 | ||
4802 | @kindex set print null-stop | |
4803 | @item set print null-stop | |
4804 | Cause @value{GDBN} to stop printing the characters of an array when the first | |
d4f3574e | 4805 | @sc{null} is encountered. This is useful when large arrays actually |
c906108c | 4806 | contain only short strings. |
d4f3574e | 4807 | The default is off. |
c906108c SS |
4808 | |
4809 | @kindex set print pretty | |
4810 | @item set print pretty on | |
4811 | Cause @value{GDBN} to print structures in an indented format with one member | |
4812 | per line, like this: | |
4813 | ||
4814 | @smallexample | |
4815 | @group | |
4816 | $1 = @{ | |
4817 | next = 0x0, | |
4818 | flags = @{ | |
4819 | sweet = 1, | |
4820 | sour = 1 | |
4821 | @}, | |
4822 | meat = 0x54 "Pork" | |
4823 | @} | |
4824 | @end group | |
4825 | @end smallexample | |
4826 | ||
4827 | @item set print pretty off | |
4828 | Cause @value{GDBN} to print structures in a compact format, like this: | |
4829 | ||
4830 | @smallexample | |
4831 | @group | |
4832 | $1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, \ | |
4833 | meat = 0x54 "Pork"@} | |
4834 | @end group | |
4835 | @end smallexample | |
4836 | ||
4837 | @noindent | |
4838 | This is the default format. | |
4839 | ||
4840 | @kindex show print pretty | |
4841 | @item show print pretty | |
4842 | Show which format @value{GDBN} is using to print structures. | |
4843 | ||
4844 | @kindex set print sevenbit-strings | |
4845 | @item set print sevenbit-strings on | |
4846 | Print using only seven-bit characters; if this option is set, | |
4847 | @value{GDBN} displays any eight-bit characters (in strings or | |
4848 | character values) using the notation @code{\}@var{nnn}. This setting is | |
4849 | best if you are working in English (@sc{ascii}) and you use the | |
4850 | high-order bit of characters as a marker or ``meta'' bit. | |
4851 | ||
4852 | @item set print sevenbit-strings off | |
4853 | Print full eight-bit characters. This allows the use of more | |
4854 | international character sets, and is the default. | |
4855 | ||
4856 | @kindex show print sevenbit-strings | |
4857 | @item show print sevenbit-strings | |
4858 | Show whether or not @value{GDBN} is printing only seven-bit characters. | |
4859 | ||
4860 | @kindex set print union | |
4861 | @item set print union on | |
4862 | Tell @value{GDBN} to print unions which are contained in structures. This | |
4863 | is the default setting. | |
4864 | ||
4865 | @item set print union off | |
4866 | Tell @value{GDBN} not to print unions which are contained in structures. | |
4867 | ||
4868 | @kindex show print union | |
4869 | @item show print union | |
4870 | Ask @value{GDBN} whether or not it will print unions which are contained in | |
4871 | structures. | |
4872 | ||
4873 | For example, given the declarations | |
4874 | ||
4875 | @smallexample | |
4876 | typedef enum @{Tree, Bug@} Species; | |
4877 | typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms; | |
4878 | typedef enum @{Caterpillar, Cocoon, Butterfly@} | |
4879 | Bug_forms; | |
4880 | ||
4881 | struct thing @{ | |
4882 | Species it; | |
4883 | union @{ | |
4884 | Tree_forms tree; | |
4885 | Bug_forms bug; | |
4886 | @} form; | |
4887 | @}; | |
4888 | ||
4889 | struct thing foo = @{Tree, @{Acorn@}@}; | |
4890 | @end smallexample | |
4891 | ||
4892 | @noindent | |
4893 | with @code{set print union on} in effect @samp{p foo} would print | |
4894 | ||
4895 | @smallexample | |
4896 | $1 = @{it = Tree, form = @{tree = Acorn, bug = Cocoon@}@} | |
4897 | @end smallexample | |
4898 | ||
4899 | @noindent | |
4900 | and with @code{set print union off} in effect it would print | |
4901 | ||
4902 | @smallexample | |
4903 | $1 = @{it = Tree, form = @{...@}@} | |
4904 | @end smallexample | |
4905 | @end table | |
4906 | ||
c906108c SS |
4907 | @need 1000 |
4908 | @noindent | |
4909 | These settings are of interest when debugging C++ programs: | |
4910 | ||
4911 | @table @code | |
4912 | @cindex demangling | |
4913 | @kindex set print demangle | |
4914 | @item set print demangle | |
4915 | @itemx set print demangle on | |
4916 | Print C++ names in their source form rather than in the encoded | |
4917 | (``mangled'') form passed to the assembler and linker for type-safe | |
d4f3574e | 4918 | linkage. The default is on. |
c906108c SS |
4919 | |
4920 | @kindex show print demangle | |
4921 | @item show print demangle | |
4922 | Show whether C++ names are printed in mangled or demangled form. | |
4923 | ||
4924 | @kindex set print asm-demangle | |
4925 | @item set print asm-demangle | |
4926 | @itemx set print asm-demangle on | |
4927 | Print C++ names in their source form rather than their mangled form, even | |
4928 | in assembler code printouts such as instruction disassemblies. | |
4929 | The default is off. | |
4930 | ||
4931 | @kindex show print asm-demangle | |
4932 | @item show print asm-demangle | |
4933 | Show whether C++ names in assembly listings are printed in mangled | |
4934 | or demangled form. | |
4935 | ||
4936 | @kindex set demangle-style | |
4937 | @cindex C++ symbol decoding style | |
4938 | @cindex symbol decoding style, C++ | |
4939 | @item set demangle-style @var{style} | |
4940 | Choose among several encoding schemes used by different compilers to | |
4941 | represent C++ names. The choices for @var{style} are currently: | |
4942 | ||
4943 | @table @code | |
4944 | @item auto | |
4945 | Allow @value{GDBN} to choose a decoding style by inspecting your program. | |
4946 | ||
4947 | @item gnu | |
4948 | Decode based on the @sc{gnu} C++ compiler (@code{g++}) encoding algorithm. | |
c906108c | 4949 | This is the default. |
c906108c SS |
4950 | |
4951 | @item hp | |
4952 | Decode based on the HP ANSI C++ (@code{aCC}) encoding algorithm. | |
4953 | ||
4954 | @item lucid | |
4955 | Decode based on the Lucid C++ compiler (@code{lcc}) encoding algorithm. | |
4956 | ||
4957 | @item arm | |
4958 | Decode using the algorithm in the @cite{C++ Annotated Reference Manual}. | |
4959 | @strong{Warning:} this setting alone is not sufficient to allow | |
4960 | debugging @code{cfront}-generated executables. @value{GDBN} would | |
4961 | require further enhancement to permit that. | |
4962 | ||
4963 | @end table | |
4964 | If you omit @var{style}, you will see a list of possible formats. | |
4965 | ||
4966 | @kindex show demangle-style | |
4967 | @item show demangle-style | |
4968 | Display the encoding style currently in use for decoding C++ symbols. | |
4969 | ||
4970 | @kindex set print object | |
4971 | @item set print object | |
4972 | @itemx set print object on | |
4973 | When displaying a pointer to an object, identify the @emph{actual} | |
4974 | (derived) type of the object rather than the @emph{declared} type, using | |
4975 | the virtual function table. | |
4976 | ||
4977 | @item set print object off | |
4978 | Display only the declared type of objects, without reference to the | |
4979 | virtual function table. This is the default setting. | |
4980 | ||
4981 | @kindex show print object | |
4982 | @item show print object | |
4983 | Show whether actual, or declared, object types are displayed. | |
4984 | ||
4985 | @kindex set print static-members | |
4986 | @item set print static-members | |
4987 | @itemx set print static-members on | |
4988 | Print static members when displaying a C++ object. The default is on. | |
4989 | ||
4990 | @item set print static-members off | |
4991 | Do not print static members when displaying a C++ object. | |
4992 | ||
4993 | @kindex show print static-members | |
4994 | @item show print static-members | |
4995 | Show whether C++ static members are printed, or not. | |
4996 | ||
4997 | @c These don't work with HP ANSI C++ yet. | |
4998 | @kindex set print vtbl | |
4999 | @item set print vtbl | |
5000 | @itemx set print vtbl on | |
5001 | Pretty print C++ virtual function tables. The default is off. | |
c906108c SS |
5002 | (The @code{vtbl} commands do not work on programs compiled with the HP |
5003 | ANSI C++ compiler (@code{aCC}).) | |
c906108c SS |
5004 | |
5005 | @item set print vtbl off | |
5006 | Do not pretty print C++ virtual function tables. | |
5007 | ||
5008 | @kindex show print vtbl | |
5009 | @item show print vtbl | |
5010 | Show whether C++ virtual function tables are pretty printed, or not. | |
5011 | @end table | |
c906108c | 5012 | |
53a5351d | 5013 | @node Value History |
c906108c SS |
5014 | @section Value history |
5015 | ||
5016 | @cindex value history | |
5017 | Values printed by the @code{print} command are saved in the @value{GDBN} | |
5018 | @dfn{value history}. This allows you to refer to them in other expressions. | |
5019 | Values are kept until the symbol table is re-read or discarded | |
5020 | (for example with the @code{file} or @code{symbol-file} commands). | |
5021 | When the symbol table changes, the value history is discarded, | |
5022 | since the values may contain pointers back to the types defined in the | |
5023 | symbol table. | |
5024 | ||
5025 | @cindex @code{$} | |
5026 | @cindex @code{$$} | |
5027 | @cindex history number | |
5028 | The values printed are given @dfn{history numbers} by which you can | |
5029 | refer to them. These are successive integers starting with one. | |
5030 | @code{print} shows you the history number assigned to a value by | |
5031 | printing @samp{$@var{num} = } before the value; here @var{num} is the | |
5032 | history number. | |
5033 | ||
5034 | To refer to any previous value, use @samp{$} followed by the value's | |
5035 | history number. The way @code{print} labels its output is designed to | |
5036 | remind you of this. Just @code{$} refers to the most recent value in | |
5037 | the history, and @code{$$} refers to the value before that. | |
5038 | @code{$$@var{n}} refers to the @var{n}th value from the end; @code{$$2} | |
5039 | is the value just prior to @code{$$}, @code{$$1} is equivalent to | |
5040 | @code{$$}, and @code{$$0} is equivalent to @code{$}. | |
5041 | ||
5042 | For example, suppose you have just printed a pointer to a structure and | |
5043 | want to see the contents of the structure. It suffices to type | |
5044 | ||
5045 | @example | |
5046 | p *$ | |
5047 | @end example | |
5048 | ||
5049 | If you have a chain of structures where the component @code{next} points | |
5050 | to the next one, you can print the contents of the next one with this: | |
5051 | ||
5052 | @example | |
5053 | p *$.next | |
5054 | @end example | |
5055 | ||
5056 | @noindent | |
5057 | You can print successive links in the chain by repeating this | |
5058 | command---which you can do by just typing @key{RET}. | |
5059 | ||
5060 | Note that the history records values, not expressions. If the value of | |
5061 | @code{x} is 4 and you type these commands: | |
5062 | ||
5063 | @example | |
5064 | print x | |
5065 | set x=5 | |
5066 | @end example | |
5067 | ||
5068 | @noindent | |
5069 | then the value recorded in the value history by the @code{print} command | |
5070 | remains 4 even though the value of @code{x} has changed. | |
5071 | ||
5072 | @table @code | |
5073 | @kindex show values | |
5074 | @item show values | |
5075 | Print the last ten values in the value history, with their item numbers. | |
5076 | This is like @samp{p@ $$9} repeated ten times, except that @code{show | |
5077 | values} does not change the history. | |
5078 | ||
5079 | @item show values @var{n} | |
5080 | Print ten history values centered on history item number @var{n}. | |
5081 | ||
5082 | @item show values + | |
5083 | Print ten history values just after the values last printed. If no more | |
5084 | values are available, @code{show values +} produces no display. | |
5085 | @end table | |
5086 | ||
5087 | Pressing @key{RET} to repeat @code{show values @var{n}} has exactly the | |
5088 | same effect as @samp{show values +}. | |
5089 | ||
53a5351d | 5090 | @node Convenience Vars |
c906108c SS |
5091 | @section Convenience variables |
5092 | ||
5093 | @cindex convenience variables | |
5094 | @value{GDBN} provides @dfn{convenience variables} that you can use within | |
5095 | @value{GDBN} to hold on to a value and refer to it later. These variables | |
5096 | exist entirely within @value{GDBN}; they are not part of your program, and | |
5097 | setting a convenience variable has no direct effect on further execution | |
5098 | of your program. That is why you can use them freely. | |
5099 | ||
5100 | Convenience variables are prefixed with @samp{$}. Any name preceded by | |
5101 | @samp{$} can be used for a convenience variable, unless it is one of | |
d4f3574e | 5102 | the predefined machine-specific register names (@pxref{Registers, ,Registers}). |
c906108c SS |
5103 | (Value history references, in contrast, are @emph{numbers} preceded |
5104 | by @samp{$}. @xref{Value History, ,Value history}.) | |
5105 | ||
5106 | You can save a value in a convenience variable with an assignment | |
5107 | expression, just as you would set a variable in your program. | |
5108 | For example: | |
5109 | ||
5110 | @example | |
5111 | set $foo = *object_ptr | |
5112 | @end example | |
5113 | ||
5114 | @noindent | |
5115 | would save in @code{$foo} the value contained in the object pointed to by | |
5116 | @code{object_ptr}. | |
5117 | ||
5118 | Using a convenience variable for the first time creates it, but its | |
5119 | value is @code{void} until you assign a new value. You can alter the | |
5120 | value with another assignment at any time. | |
5121 | ||
5122 | Convenience variables have no fixed types. You can assign a convenience | |
5123 | variable any type of value, including structures and arrays, even if | |
5124 | that variable already has a value of a different type. The convenience | |
5125 | variable, when used as an expression, has the type of its current value. | |
5126 | ||
5127 | @table @code | |
5128 | @kindex show convenience | |
5129 | @item show convenience | |
5130 | Print a list of convenience variables used so far, and their values. | |
d4f3574e | 5131 | Abbreviated @code{show conv}. |
c906108c SS |
5132 | @end table |
5133 | ||
5134 | One of the ways to use a convenience variable is as a counter to be | |
5135 | incremented or a pointer to be advanced. For example, to print | |
5136 | a field from successive elements of an array of structures: | |
5137 | ||
5138 | @example | |
5139 | set $i = 0 | |
5140 | print bar[$i++]->contents | |
5141 | @end example | |
5142 | ||
d4f3574e SS |
5143 | @noindent |
5144 | Repeat that command by typing @key{RET}. | |
c906108c SS |
5145 | |
5146 | Some convenience variables are created automatically by @value{GDBN} and given | |
5147 | values likely to be useful. | |
5148 | ||
5149 | @table @code | |
5150 | @kindex $_ | |
5151 | @item $_ | |
5152 | The variable @code{$_} is automatically set by the @code{x} command to | |
5153 | the last address examined (@pxref{Memory, ,Examining memory}). Other | |
5154 | commands which provide a default address for @code{x} to examine also | |
5155 | set @code{$_} to that address; these commands include @code{info line} | |
5156 | and @code{info breakpoint}. The type of @code{$_} is @code{void *} | |
5157 | except when set by the @code{x} command, in which case it is a pointer | |
5158 | to the type of @code{$__}. | |
5159 | ||
5160 | @kindex $__ | |
5161 | @item $__ | |
5162 | The variable @code{$__} is automatically set by the @code{x} command | |
5163 | to the value found in the last address examined. Its type is chosen | |
5164 | to match the format in which the data was printed. | |
5165 | ||
5166 | @item $_exitcode | |
5167 | @kindex $_exitcode | |
5168 | The variable @code{$_exitcode} is automatically set to the exit code when | |
5169 | the program being debugged terminates. | |
5170 | @end table | |
5171 | ||
53a5351d JM |
5172 | On HP-UX systems, if you refer to a function or variable name that |
5173 | begins with a dollar sign, @value{GDBN} searches for a user or system | |
5174 | name first, before it searches for a convenience variable. | |
c906108c | 5175 | |
53a5351d | 5176 | @node Registers |
c906108c SS |
5177 | @section Registers |
5178 | ||
5179 | @cindex registers | |
5180 | You can refer to machine register contents, in expressions, as variables | |
5181 | with names starting with @samp{$}. The names of registers are different | |
5182 | for each machine; use @code{info registers} to see the names used on | |
5183 | your machine. | |
5184 | ||
5185 | @table @code | |
5186 | @kindex info registers | |
5187 | @item info registers | |
5188 | Print the names and values of all registers except floating-point | |
5189 | registers (in the selected stack frame). | |
5190 | ||
5191 | @kindex info all-registers | |
5192 | @cindex floating point registers | |
5193 | @item info all-registers | |
5194 | Print the names and values of all registers, including floating-point | |
5195 | registers. | |
5196 | ||
5197 | @item info registers @var{regname} @dots{} | |
5198 | Print the @dfn{relativized} value of each specified register @var{regname}. | |
5199 | As discussed in detail below, register values are normally relative to | |
5200 | the selected stack frame. @var{regname} may be any register name valid on | |
5201 | the machine you are using, with or without the initial @samp{$}. | |
5202 | @end table | |
5203 | ||
5204 | @value{GDBN} has four ``standard'' register names that are available (in | |
5205 | expressions) on most machines---whenever they do not conflict with an | |
5206 | architecture's canonical mnemonics for registers. The register names | |
5207 | @code{$pc} and @code{$sp} are used for the program counter register and | |
5208 | the stack pointer. @code{$fp} is used for a register that contains a | |
5209 | pointer to the current stack frame, and @code{$ps} is used for a | |
5210 | register that contains the processor status. For example, | |
5211 | you could print the program counter in hex with | |
5212 | ||
5213 | @example | |
5214 | p/x $pc | |
5215 | @end example | |
5216 | ||
5217 | @noindent | |
5218 | or print the instruction to be executed next with | |
5219 | ||
5220 | @example | |
5221 | x/i $pc | |
5222 | @end example | |
5223 | ||
5224 | @noindent | |
5225 | or add four to the stack pointer@footnote{This is a way of removing | |
5226 | one word from the stack, on machines where stacks grow downward in | |
5227 | memory (most machines, nowadays). This assumes that the innermost | |
5228 | stack frame is selected; setting @code{$sp} is not allowed when other | |
5229 | stack frames are selected. To pop entire frames off the stack, | |
5230 | regardless of machine architecture, use @code{return}; | |
d4f3574e | 5231 | see @ref{Returning, ,Returning from a function}.} with |
c906108c SS |
5232 | |
5233 | @example | |
5234 | set $sp += 4 | |
5235 | @end example | |
5236 | ||
5237 | Whenever possible, these four standard register names are available on | |
5238 | your machine even though the machine has different canonical mnemonics, | |
5239 | so long as there is no conflict. The @code{info registers} command | |
5240 | shows the canonical names. For example, on the SPARC, @code{info | |
5241 | registers} displays the processor status register as @code{$psr} but you | |
d4f3574e SS |
5242 | can also refer to it as @code{$ps}; and on x86-based machines @code{$ps} |
5243 | is an alias for the @sc{eflags} register. | |
c906108c SS |
5244 | |
5245 | @value{GDBN} always considers the contents of an ordinary register as an | |
5246 | integer when the register is examined in this way. Some machines have | |
5247 | special registers which can hold nothing but floating point; these | |
5248 | registers are considered to have floating point values. There is no way | |
5249 | to refer to the contents of an ordinary register as floating point value | |
5250 | (although you can @emph{print} it as a floating point value with | |
5251 | @samp{print/f $@var{regname}}). | |
5252 | ||
5253 | Some registers have distinct ``raw'' and ``virtual'' data formats. This | |
5254 | means that the data format in which the register contents are saved by | |
5255 | the operating system is not the same one that your program normally | |
5256 | sees. For example, the registers of the 68881 floating point | |
5257 | coprocessor are always saved in ``extended'' (raw) format, but all C | |
5258 | programs expect to work with ``double'' (virtual) format. In such | |
5259 | cases, @value{GDBN} normally works with the virtual format only (the format | |
5260 | that makes sense for your program), but the @code{info registers} command | |
5261 | prints the data in both formats. | |
5262 | ||
5263 | Normally, register values are relative to the selected stack frame | |
5264 | (@pxref{Selection, ,Selecting a frame}). This means that you get the | |
5265 | value that the register would contain if all stack frames farther in | |
5266 | were exited and their saved registers restored. In order to see the | |
5267 | true contents of hardware registers, you must select the innermost | |
5268 | frame (with @samp{frame 0}). | |
5269 | ||
5270 | However, @value{GDBN} must deduce where registers are saved, from the machine | |
5271 | code generated by your compiler. If some registers are not saved, or if | |
5272 | @value{GDBN} is unable to locate the saved registers, the selected stack | |
5273 | frame makes no difference. | |
5274 | ||
53a5351d | 5275 | @node Floating Point Hardware |
c906108c SS |
5276 | @section Floating point hardware |
5277 | @cindex floating point | |
5278 | ||
5279 | Depending on the configuration, @value{GDBN} may be able to give | |
5280 | you more information about the status of the floating point hardware. | |
5281 | ||
5282 | @table @code | |
5283 | @kindex info float | |
5284 | @item info float | |
5285 | Display hardware-dependent information about the floating | |
5286 | point unit. The exact contents and layout vary depending on the | |
5287 | floating point chip. Currently, @samp{info float} is supported on | |
5288 | the ARM and x86 machines. | |
5289 | @end table | |
c906108c | 5290 | |
53a5351d | 5291 | @node Languages |
c906108c SS |
5292 | @chapter Using @value{GDBN} with Different Languages |
5293 | @cindex languages | |
5294 | ||
c906108c SS |
5295 | Although programming languages generally have common aspects, they are |
5296 | rarely expressed in the same manner. For instance, in ANSI C, | |
5297 | dereferencing a pointer @code{p} is accomplished by @code{*p}, but in | |
5298 | Modula-2, it is accomplished by @code{p^}. Values can also be | |
5299 | represented (and displayed) differently. Hex numbers in C appear as | |
5300 | @samp{0x1ae}, while in Modula-2 they appear as @samp{1AEH}. | |
c906108c SS |
5301 | |
5302 | @cindex working language | |
5303 | Language-specific information is built into @value{GDBN} for some languages, | |
5304 | allowing you to express operations like the above in your program's | |
5305 | native language, and allowing @value{GDBN} to output values in a manner | |
5306 | consistent with the syntax of your program's native language. The | |
5307 | language you use to build expressions is called the @dfn{working | |
5308 | language}. | |
5309 | ||
5310 | @menu | |
5311 | * Setting:: Switching between source languages | |
5312 | * Show:: Displaying the language | |
c906108c | 5313 | * Checks:: Type and range checks |
c906108c SS |
5314 | * Support:: Supported languages |
5315 | @end menu | |
5316 | ||
53a5351d | 5317 | @node Setting |
c906108c SS |
5318 | @section Switching between source languages |
5319 | ||
5320 | There are two ways to control the working language---either have @value{GDBN} | |
5321 | set it automatically, or select it manually yourself. You can use the | |
5322 | @code{set language} command for either purpose. On startup, @value{GDBN} | |
5323 | defaults to setting the language automatically. The working language is | |
5324 | used to determine how expressions you type are interpreted, how values | |
5325 | are printed, etc. | |
5326 | ||
5327 | In addition to the working language, every source file that | |
5328 | @value{GDBN} knows about has its own working language. For some object | |
5329 | file formats, the compiler might indicate which language a particular | |
5330 | source file is in. However, most of the time @value{GDBN} infers the | |
5331 | language from the name of the file. The language of a source file | |
5332 | controls whether C++ names are demangled---this way @code{backtrace} can | |
5333 | show each frame appropriately for its own language. There is no way to | |
d4f3574e SS |
5334 | set the language of a source file from within @value{GDBN}, but you can |
5335 | set the language associated with a filename extension. @xref{Show, , | |
5336 | Displaying the language}. | |
c906108c SS |
5337 | |
5338 | This is most commonly a problem when you use a program, such | |
5339 | as @code{cfront} or @code{f2c}, that generates C but is written in | |
5340 | another language. In that case, make the | |
5341 | program use @code{#line} directives in its C output; that way | |
5342 | @value{GDBN} will know the correct language of the source code of the original | |
5343 | program, and will display that source code, not the generated C code. | |
5344 | ||
5345 | @menu | |
5346 | * Filenames:: Filename extensions and languages. | |
5347 | * Manually:: Setting the working language manually | |
5348 | * Automatically:: Having @value{GDBN} infer the source language | |
5349 | @end menu | |
5350 | ||
53a5351d | 5351 | @node Filenames |
c906108c SS |
5352 | @subsection List of filename extensions and languages |
5353 | ||
5354 | If a source file name ends in one of the following extensions, then | |
5355 | @value{GDBN} infers that its language is the one indicated. | |
5356 | ||
5357 | @table @file | |
5358 | ||
5359 | @item .c | |
5360 | C source file | |
5361 | ||
5362 | @item .C | |
5363 | @itemx .cc | |
5364 | @itemx .cp | |
5365 | @itemx .cpp | |
5366 | @itemx .cxx | |
5367 | @itemx .c++ | |
5368 | C++ source file | |
5369 | ||
5370 | @item .f | |
5371 | @itemx .F | |
5372 | Fortran source file | |
5373 | ||
c906108c SS |
5374 | @item .ch |
5375 | @itemx .c186 | |
5376 | @itemx .c286 | |
5377 | CHILL source file. | |
c906108c | 5378 | |
c906108c SS |
5379 | @item .mod |
5380 | Modula-2 source file | |
c906108c SS |
5381 | |
5382 | @item .s | |
5383 | @itemx .S | |
5384 | Assembler source file. This actually behaves almost like C, but | |
5385 | @value{GDBN} does not skip over function prologues when stepping. | |
5386 | @end table | |
5387 | ||
5388 | In addition, you may set the language associated with a filename | |
5389 | extension. @xref{Show, , Displaying the language}. | |
5390 | ||
53a5351d | 5391 | @node Manually |
c906108c SS |
5392 | @subsection Setting the working language |
5393 | ||
5394 | If you allow @value{GDBN} to set the language automatically, | |
5395 | expressions are interpreted the same way in your debugging session and | |
5396 | your program. | |
5397 | ||
5398 | @kindex set language | |
5399 | If you wish, you may set the language manually. To do this, issue the | |
5400 | command @samp{set language @var{lang}}, where @var{lang} is the name of | |
5401 | a language, such as | |
c906108c | 5402 | @code{c} or @code{modula-2}. |
c906108c SS |
5403 | For a list of the supported languages, type @samp{set language}. |
5404 | ||
c906108c SS |
5405 | Setting the language manually prevents @value{GDBN} from updating the working |
5406 | language automatically. This can lead to confusion if you try | |
5407 | to debug a program when the working language is not the same as the | |
5408 | source language, when an expression is acceptable to both | |
5409 | languages---but means different things. For instance, if the current | |
5410 | source file were written in C, and @value{GDBN} was parsing Modula-2, a | |
5411 | command such as: | |
5412 | ||
5413 | @example | |
5414 | print a = b + c | |
5415 | @end example | |
5416 | ||
5417 | @noindent | |
5418 | might not have the effect you intended. In C, this means to add | |
5419 | @code{b} and @code{c} and place the result in @code{a}. The result | |
5420 | printed would be the value of @code{a}. In Modula-2, this means to compare | |
5421 | @code{a} to the result of @code{b+c}, yielding a @code{BOOLEAN} value. | |
c906108c | 5422 | |
53a5351d | 5423 | @node Automatically |
c906108c SS |
5424 | @subsection Having @value{GDBN} infer the source language |
5425 | ||
5426 | To have @value{GDBN} set the working language automatically, use | |
5427 | @samp{set language local} or @samp{set language auto}. @value{GDBN} | |
5428 | then infers the working language. That is, when your program stops in a | |
5429 | frame (usually by encountering a breakpoint), @value{GDBN} sets the | |
5430 | working language to the language recorded for the function in that | |
5431 | frame. If the language for a frame is unknown (that is, if the function | |
5432 | or block corresponding to the frame was defined in a source file that | |
5433 | does not have a recognized extension), the current working language is | |
5434 | not changed, and @value{GDBN} issues a warning. | |
5435 | ||
5436 | This may not seem necessary for most programs, which are written | |
5437 | entirely in one source language. However, program modules and libraries | |
5438 | written in one source language can be used by a main program written in | |
5439 | a different source language. Using @samp{set language auto} in this | |
5440 | case frees you from having to set the working language manually. | |
5441 | ||
53a5351d | 5442 | @node Show |
c906108c | 5443 | @section Displaying the language |
c906108c SS |
5444 | |
5445 | The following commands help you find out which language is the | |
5446 | working language, and also what language source files were written in. | |
5447 | ||
5448 | @kindex show language | |
d4f3574e SS |
5449 | @kindex info frame@r{, show the source language} |
5450 | @kindex info source@r{, show the source language} | |
c906108c SS |
5451 | @table @code |
5452 | @item show language | |
5453 | Display the current working language. This is the | |
5454 | language you can use with commands such as @code{print} to | |
5455 | build and compute expressions that may involve variables in your program. | |
5456 | ||
5457 | @item info frame | |
5458 | Display the source language for this frame. This language becomes the | |
5459 | working language if you use an identifier from this frame. | |
5460 | @xref{Frame Info, ,Information about a frame}, to identify the other | |
5461 | information listed here. | |
5462 | ||
5463 | @item info source | |
5464 | Display the source language of this source file. | |
5465 | @xref{Symbols, ,Examining the Symbol Table}, to identify the other | |
5466 | information listed here. | |
5467 | @end table | |
5468 | ||
5469 | In unusual circumstances, you may have source files with extensions | |
5470 | not in the standard list. You can then set the extension associated | |
5471 | with a language explicitly: | |
5472 | ||
5473 | @kindex set extension-language | |
5474 | @kindex info extensions | |
5475 | @table @code | |
5476 | @item set extension-language @var{.ext} @var{language} | |
5477 | Set source files with extension @var{.ext} to be assumed to be in | |
5478 | the source language @var{language}. | |
5479 | ||
5480 | @item info extensions | |
5481 | List all the filename extensions and the associated languages. | |
5482 | @end table | |
5483 | ||
53a5351d | 5484 | @node Checks |
c906108c SS |
5485 | @section Type and range checking |
5486 | ||
5487 | @quotation | |
5488 | @emph{Warning:} In this release, the @value{GDBN} commands for type and range | |
5489 | checking are included, but they do not yet have any effect. This | |
5490 | section documents the intended facilities. | |
5491 | @end quotation | |
5492 | @c FIXME remove warning when type/range code added | |
5493 | ||
5494 | Some languages are designed to guard you against making seemingly common | |
5495 | errors through a series of compile- and run-time checks. These include | |
5496 | checking the type of arguments to functions and operators, and making | |
5497 | sure mathematical overflows are caught at run time. Checks such as | |
5498 | these help to ensure a program's correctness once it has been compiled | |
5499 | by eliminating type mismatches, and providing active checks for range | |
5500 | errors when your program is running. | |
5501 | ||
5502 | @value{GDBN} can check for conditions like the above if you wish. | |
5503 | Although @value{GDBN} does not check the statements in your program, it | |
5504 | can check expressions entered directly into @value{GDBN} for evaluation via | |
5505 | the @code{print} command, for example. As with the working language, | |
5506 | @value{GDBN} can also decide whether or not to check automatically based on | |
5507 | your program's source language. @xref{Support, ,Supported languages}, | |
5508 | for the default settings of supported languages. | |
5509 | ||
5510 | @menu | |
5511 | * Type Checking:: An overview of type checking | |
5512 | * Range Checking:: An overview of range checking | |
5513 | @end menu | |
5514 | ||
5515 | @cindex type checking | |
5516 | @cindex checks, type | |
53a5351d | 5517 | @node Type Checking |
c906108c SS |
5518 | @subsection An overview of type checking |
5519 | ||
5520 | Some languages, such as Modula-2, are strongly typed, meaning that the | |
5521 | arguments to operators and functions have to be of the correct type, | |
5522 | otherwise an error occurs. These checks prevent type mismatch | |
5523 | errors from ever causing any run-time problems. For example, | |
5524 | ||
5525 | @smallexample | |
5526 | 1 + 2 @result{} 3 | |
5527 | @exdent but | |
5528 | @error{} 1 + 2.3 | |
5529 | @end smallexample | |
5530 | ||
5531 | The second example fails because the @code{CARDINAL} 1 is not | |
5532 | type-compatible with the @code{REAL} 2.3. | |
5533 | ||
5534 | For the expressions you use in @value{GDBN} commands, you can tell the | |
5535 | @value{GDBN} type checker to skip checking; | |
5536 | to treat any mismatches as errors and abandon the expression; | |
5537 | or to only issue warnings when type mismatches occur, | |
5538 | but evaluate the expression anyway. When you choose the last of | |
5539 | these, @value{GDBN} evaluates expressions like the second example above, but | |
5540 | also issues a warning. | |
5541 | ||
5542 | Even if you turn type checking off, there may be other reasons | |
5543 | related to type that prevent @value{GDBN} from evaluating an expression. | |
5544 | For instance, @value{GDBN} does not know how to add an @code{int} and | |
5545 | a @code{struct foo}. These particular type errors have nothing to do | |
5546 | with the language in use, and usually arise from expressions, such as | |
5547 | the one described above, which make little sense to evaluate anyway. | |
5548 | ||
5549 | Each language defines to what degree it is strict about type. For | |
5550 | instance, both Modula-2 and C require the arguments to arithmetical | |
5551 | operators to be numbers. In C, enumerated types and pointers can be | |
5552 | represented as numbers, so that they are valid arguments to mathematical | |
5553 | operators. @xref{Support, ,Supported languages}, for further | |
5554 | details on specific languages. | |
5555 | ||
5556 | @value{GDBN} provides some additional commands for controlling the type checker: | |
5557 | ||
d4f3574e | 5558 | @kindex set check@r{, type} |
c906108c SS |
5559 | @kindex set check type |
5560 | @kindex show check type | |
5561 | @table @code | |
5562 | @item set check type auto | |
5563 | Set type checking on or off based on the current working language. | |
5564 | @xref{Support, ,Supported languages}, for the default settings for | |
5565 | each language. | |
5566 | ||
5567 | @item set check type on | |
5568 | @itemx set check type off | |
5569 | Set type checking on or off, overriding the default setting for the | |
5570 | current working language. Issue a warning if the setting does not | |
5571 | match the language default. If any type mismatches occur in | |
d4f3574e | 5572 | evaluating an expression while type checking is on, @value{GDBN} prints a |
c906108c SS |
5573 | message and aborts evaluation of the expression. |
5574 | ||
5575 | @item set check type warn | |
5576 | Cause the type checker to issue warnings, but to always attempt to | |
5577 | evaluate the expression. Evaluating the expression may still | |
5578 | be impossible for other reasons. For example, @value{GDBN} cannot add | |
5579 | numbers and structures. | |
5580 | ||
5581 | @item show type | |
5582 | Show the current setting of the type checker, and whether or not @value{GDBN} | |
5583 | is setting it automatically. | |
5584 | @end table | |
5585 | ||
5586 | @cindex range checking | |
5587 | @cindex checks, range | |
53a5351d | 5588 | @node Range Checking |
c906108c SS |
5589 | @subsection An overview of range checking |
5590 | ||
5591 | In some languages (such as Modula-2), it is an error to exceed the | |
5592 | bounds of a type; this is enforced with run-time checks. Such range | |
5593 | checking is meant to ensure program correctness by making sure | |
5594 | computations do not overflow, or indices on an array element access do | |
5595 | not exceed the bounds of the array. | |
5596 | ||
5597 | For expressions you use in @value{GDBN} commands, you can tell | |
5598 | @value{GDBN} to treat range errors in one of three ways: ignore them, | |
5599 | always treat them as errors and abandon the expression, or issue | |
5600 | warnings but evaluate the expression anyway. | |
5601 | ||
5602 | A range error can result from numerical overflow, from exceeding an | |
5603 | array index bound, or when you type a constant that is not a member | |
5604 | of any type. Some languages, however, do not treat overflows as an | |
5605 | error. In many implementations of C, mathematical overflow causes the | |
5606 | result to ``wrap around'' to lower values---for example, if @var{m} is | |
5607 | the largest integer value, and @var{s} is the smallest, then | |
5608 | ||
5609 | @example | |
5610 | @var{m} + 1 @result{} @var{s} | |
5611 | @end example | |
5612 | ||
5613 | This, too, is specific to individual languages, and in some cases | |
5614 | specific to individual compilers or machines. @xref{Support, , | |
5615 | Supported languages}, for further details on specific languages. | |
5616 | ||
5617 | @value{GDBN} provides some additional commands for controlling the range checker: | |
5618 | ||
d4f3574e | 5619 | @kindex set check@r{, range} |
c906108c SS |
5620 | @kindex set check range |
5621 | @kindex show check range | |
5622 | @table @code | |
5623 | @item set check range auto | |
5624 | Set range checking on or off based on the current working language. | |
5625 | @xref{Support, ,Supported languages}, for the default settings for | |
5626 | each language. | |
5627 | ||
5628 | @item set check range on | |
5629 | @itemx set check range off | |
5630 | Set range checking on or off, overriding the default setting for the | |
5631 | current working language. A warning is issued if the setting does not | |
c3f6f71d JM |
5632 | match the language default. If a range error occurs and range checking is on, |
5633 | then a message is printed and evaluation of the expression is aborted. | |
c906108c SS |
5634 | |
5635 | @item set check range warn | |
5636 | Output messages when the @value{GDBN} range checker detects a range error, | |
5637 | but attempt to evaluate the expression anyway. Evaluating the | |
5638 | expression may still be impossible for other reasons, such as accessing | |
5639 | memory that the process does not own (a typical example from many Unix | |
5640 | systems). | |
5641 | ||
5642 | @item show range | |
5643 | Show the current setting of the range checker, and whether or not it is | |
5644 | being set automatically by @value{GDBN}. | |
5645 | @end table | |
c906108c | 5646 | |
53a5351d | 5647 | @node Support |
c906108c | 5648 | @section Supported languages |
c906108c | 5649 | |
cce74817 JM |
5650 | @value{GDBN} supports C, C++, Fortran, Java, Chill, assembly, and Modula-2. |
5651 | @c This is false ... | |
c906108c SS |
5652 | Some @value{GDBN} features may be used in expressions regardless of the |
5653 | language you use: the @value{GDBN} @code{@@} and @code{::} operators, | |
5654 | and the @samp{@{type@}addr} construct (@pxref{Expressions, | |
5655 | ,Expressions}) can be used with the constructs of any supported | |
5656 | language. | |
5657 | ||
5658 | The following sections detail to what degree each source language is | |
5659 | supported by @value{GDBN}. These sections are not meant to be language | |
5660 | tutorials or references, but serve only as a reference guide to what the | |
5661 | @value{GDBN} expression parser accepts, and what input and output | |
5662 | formats should look like for different languages. There are many good | |
5663 | books written on each of these languages; please look to these for a | |
5664 | language reference or tutorial. | |
5665 | ||
c906108c | 5666 | @menu |
7a292a7a | 5667 | * C:: C and C++ |
cce74817 | 5668 | * Modula-2:: Modula-2 |
104c1213 | 5669 | * Chill:: Chill |
c906108c SS |
5670 | @end menu |
5671 | ||
53a5351d | 5672 | @node C |
c906108c | 5673 | @subsection C and C++ |
7a292a7a | 5674 | |
c906108c SS |
5675 | @cindex C and C++ |
5676 | @cindex expressions in C or C++ | |
c906108c SS |
5677 | |
5678 | Since C and C++ are so closely related, many features of @value{GDBN} apply | |
5679 | to both languages. Whenever this is the case, we discuss those languages | |
5680 | together. | |
5681 | ||
c906108c SS |
5682 | @cindex C++ |
5683 | @kindex g++ | |
5684 | @cindex @sc{gnu} C++ | |
5685 | The C++ debugging facilities are jointly implemented by the C++ | |
5686 | compiler and @value{GDBN}. Therefore, to debug your C++ code | |
5687 | effectively, you must compile your C++ programs with a supported | |
5688 | C++ compiler, such as @sc{gnu} @code{g++}, or the HP ANSI C++ | |
5689 | compiler (@code{aCC}). | |
5690 | ||
5691 | For best results when using @sc{gnu} C++, use the stabs debugging | |
5692 | format. You can select that format explicitly with the @code{g++} | |
5693 | command-line options @samp{-gstabs} or @samp{-gstabs+}. See | |
5694 | @ref{Debugging Options,,Options for Debugging Your Program or @sc{gnu} | |
5695 | CC, gcc.info, Using @sc{gnu} CC}, for more information. | |
c906108c | 5696 | |
c906108c SS |
5697 | @menu |
5698 | * C Operators:: C and C++ operators | |
5699 | * C Constants:: C and C++ constants | |
7a292a7a | 5700 | * C plus plus expressions:: C++ expressions |
c906108c | 5701 | * C Defaults:: Default settings for C and C++ |
c906108c | 5702 | * C Checks:: C and C++ type and range checks |
c906108c SS |
5703 | * Debugging C:: @value{GDBN} and C |
5704 | * Debugging C plus plus:: @value{GDBN} features for C++ | |
5705 | @end menu | |
c906108c | 5706 | |
53a5351d | 5707 | @node C Operators |
c906108c | 5708 | @subsubsection C and C++ operators |
7a292a7a SS |
5709 | |
5710 | @cindex C and C++ operators | |
c906108c SS |
5711 | |
5712 | Operators must be defined on values of specific types. For instance, | |
5713 | @code{+} is defined on numbers, but not on structures. Operators are | |
5714 | often defined on groups of types. | |
5715 | ||
c906108c | 5716 | For the purposes of C and C++, the following definitions hold: |
c906108c SS |
5717 | |
5718 | @itemize @bullet | |
53a5351d | 5719 | |
c906108c | 5720 | @item |
c906108c SS |
5721 | @emph{Integral types} include @code{int} with any of its storage-class |
5722 | specifiers; @code{char}; @code{enum}; and, for C++, @code{bool}. | |
c906108c SS |
5723 | |
5724 | @item | |
d4f3574e SS |
5725 | @emph{Floating-point types} include @code{float}, @code{double}, and |
5726 | @code{long double} (if supported by the target platform). | |
c906108c SS |
5727 | |
5728 | @item | |
53a5351d | 5729 | @emph{Pointer types} include all types defined as @code{(@var{type} *)}. |
c906108c SS |
5730 | |
5731 | @item | |
5732 | @emph{Scalar types} include all of the above. | |
53a5351d | 5733 | |
c906108c SS |
5734 | @end itemize |
5735 | ||
5736 | @noindent | |
5737 | The following operators are supported. They are listed here | |
5738 | in order of increasing precedence: | |
5739 | ||
5740 | @table @code | |
5741 | @item , | |
5742 | The comma or sequencing operator. Expressions in a comma-separated list | |
5743 | are evaluated from left to right, with the result of the entire | |
5744 | expression being the last expression evaluated. | |
5745 | ||
5746 | @item = | |
5747 | Assignment. The value of an assignment expression is the value | |
5748 | assigned. Defined on scalar types. | |
5749 | ||
5750 | @item @var{op}= | |
5751 | Used in an expression of the form @w{@code{@var{a} @var{op}= @var{b}}}, | |
5752 | and translated to @w{@code{@var{a} = @var{a op b}}}. | |
d4f3574e | 5753 | @w{@code{@var{op}=}} and @code{=} have the same precedence. |
c906108c SS |
5754 | @var{op} is any one of the operators @code{|}, @code{^}, @code{&}, |
5755 | @code{<<}, @code{>>}, @code{+}, @code{-}, @code{*}, @code{/}, @code{%}. | |
5756 | ||
5757 | @item ?: | |
5758 | The ternary operator. @code{@var{a} ? @var{b} : @var{c}} can be thought | |
5759 | of as: if @var{a} then @var{b} else @var{c}. @var{a} should be of an | |
5760 | integral type. | |
5761 | ||
5762 | @item || | |
5763 | Logical @sc{or}. Defined on integral types. | |
5764 | ||
5765 | @item && | |
5766 | Logical @sc{and}. Defined on integral types. | |
5767 | ||
5768 | @item | | |
5769 | Bitwise @sc{or}. Defined on integral types. | |
5770 | ||
5771 | @item ^ | |
5772 | Bitwise exclusive-@sc{or}. Defined on integral types. | |
5773 | ||
5774 | @item & | |
5775 | Bitwise @sc{and}. Defined on integral types. | |
5776 | ||
5777 | @item ==@r{, }!= | |
5778 | Equality and inequality. Defined on scalar types. The value of these | |
5779 | expressions is 0 for false and non-zero for true. | |
5780 | ||
5781 | @item <@r{, }>@r{, }<=@r{, }>= | |
5782 | Less than, greater than, less than or equal, greater than or equal. | |
5783 | Defined on scalar types. The value of these expressions is 0 for false | |
5784 | and non-zero for true. | |
5785 | ||
5786 | @item <<@r{, }>> | |
5787 | left shift, and right shift. Defined on integral types. | |
5788 | ||
5789 | @item @@ | |
5790 | The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}). | |
5791 | ||
5792 | @item +@r{, }- | |
5793 | Addition and subtraction. Defined on integral types, floating-point types and | |
5794 | pointer types. | |
5795 | ||
5796 | @item *@r{, }/@r{, }% | |
5797 | Multiplication, division, and modulus. Multiplication and division are | |
5798 | defined on integral and floating-point types. Modulus is defined on | |
5799 | integral types. | |
5800 | ||
5801 | @item ++@r{, }-- | |
5802 | Increment and decrement. When appearing before a variable, the | |
5803 | operation is performed before the variable is used in an expression; | |
5804 | when appearing after it, the variable's value is used before the | |
5805 | operation takes place. | |
5806 | ||
5807 | @item * | |
5808 | Pointer dereferencing. Defined on pointer types. Same precedence as | |
5809 | @code{++}. | |
5810 | ||
5811 | @item & | |
5812 | Address operator. Defined on variables. Same precedence as @code{++}. | |
5813 | ||
c906108c SS |
5814 | For debugging C++, @value{GDBN} implements a use of @samp{&} beyond what is |
5815 | allowed in the C++ language itself: you can use @samp{&(&@var{ref})} | |
5816 | (or, if you prefer, simply @samp{&&@var{ref}}) to examine the address | |
5817 | where a C++ reference variable (declared with @samp{&@var{ref}}) is | |
5818 | stored. | |
c906108c SS |
5819 | |
5820 | @item - | |
5821 | Negative. Defined on integral and floating-point types. Same | |
5822 | precedence as @code{++}. | |
5823 | ||
5824 | @item ! | |
5825 | Logical negation. Defined on integral types. Same precedence as | |
5826 | @code{++}. | |
5827 | ||
5828 | @item ~ | |
5829 | Bitwise complement operator. Defined on integral types. Same precedence as | |
5830 | @code{++}. | |
5831 | ||
5832 | ||
5833 | @item .@r{, }-> | |
5834 | Structure member, and pointer-to-structure member. For convenience, | |
5835 | @value{GDBN} regards the two as equivalent, choosing whether to dereference a | |
5836 | pointer based on the stored type information. | |
5837 | Defined on @code{struct} and @code{union} data. | |
5838 | ||
c906108c SS |
5839 | @item .*@r{, }->* |
5840 | Dereferences of pointers to members. | |
c906108c SS |
5841 | |
5842 | @item [] | |
5843 | Array indexing. @code{@var{a}[@var{i}]} is defined as | |
5844 | @code{*(@var{a}+@var{i})}. Same precedence as @code{->}. | |
5845 | ||
5846 | @item () | |
5847 | Function parameter list. Same precedence as @code{->}. | |
5848 | ||
c906108c | 5849 | @item :: |
7a292a7a SS |
5850 | C++ scope resolution operator. Defined on @code{struct}, @code{union}, |
5851 | and @code{class} types. | |
c906108c SS |
5852 | |
5853 | @item :: | |
7a292a7a SS |
5854 | Doubled colons also represent the @value{GDBN} scope operator |
5855 | (@pxref{Expressions, ,Expressions}). Same precedence as @code{::}, | |
5856 | above. | |
c906108c SS |
5857 | @end table |
5858 | ||
c906108c SS |
5859 | If an operator is redefined in the user code, @value{GDBN} usually |
5860 | attempts to invoke the redefined version instead of using the operator's | |
5861 | predefined meaning. | |
c906108c | 5862 | |
c906108c SS |
5863 | @menu |
5864 | * C Constants:: | |
5865 | @end menu | |
5866 | ||
53a5351d | 5867 | @node C Constants |
c906108c | 5868 | @subsubsection C and C++ constants |
c906108c SS |
5869 | |
5870 | @cindex C and C++ constants | |
c906108c | 5871 | |
7a292a7a | 5872 | @value{GDBN} allows you to express the constants of C and C++ in the |
c906108c | 5873 | following ways: |
c906108c SS |
5874 | |
5875 | @itemize @bullet | |
5876 | @item | |
5877 | Integer constants are a sequence of digits. Octal constants are | |
5878 | specified by a leading @samp{0} (i.e. zero), and hexadecimal constants by | |
5879 | a leading @samp{0x} or @samp{0X}. Constants may also end with a letter | |
5880 | @samp{l}, specifying that the constant should be treated as a | |
5881 | @code{long} value. | |
5882 | ||
5883 | @item | |
5884 | Floating point constants are a sequence of digits, followed by a decimal | |
5885 | point, followed by a sequence of digits, and optionally followed by an | |
5886 | exponent. An exponent is of the form: | |
5887 | @samp{@w{e@r{[[}+@r{]|}-@r{]}@var{nnn}}}, where @var{nnn} is another | |
5888 | sequence of digits. The @samp{+} is optional for positive exponents. | |
d4f3574e SS |
5889 | A floating-point constant may also end with a letter @samp{f} or |
5890 | @samp{F}, specifying that the constant should be treated as being of | |
5891 | the @code{float} (as opposed to the default @code{double}) type; or with | |
5892 | a letter @samp{l} or @samp{L}, which specifies a @code{long double} | |
5893 | constant. | |
c906108c SS |
5894 | |
5895 | @item | |
5896 | Enumerated constants consist of enumerated identifiers, or their | |
5897 | integral equivalents. | |
5898 | ||
5899 | @item | |
5900 | Character constants are a single character surrounded by single quotes | |
5901 | (@code{'}), or a number---the ordinal value of the corresponding character | |
d4f3574e | 5902 | (usually its @sc{ascii} value). Within quotes, the single character may |
c906108c SS |
5903 | be represented by a letter or by @dfn{escape sequences}, which are of |
5904 | the form @samp{\@var{nnn}}, where @var{nnn} is the octal representation | |
5905 | of the character's ordinal value; or of the form @samp{\@var{x}}, where | |
5906 | @samp{@var{x}} is a predefined special character---for example, | |
5907 | @samp{\n} for newline. | |
5908 | ||
5909 | @item | |
5910 | String constants are a sequence of character constants surrounded | |
5911 | by double quotes (@code{"}). | |
5912 | ||
5913 | @item | |
5914 | Pointer constants are an integral value. You can also write pointers | |
5915 | to constants using the C operator @samp{&}. | |
5916 | ||
5917 | @item | |
5918 | Array constants are comma-separated lists surrounded by braces @samp{@{} | |
5919 | and @samp{@}}; for example, @samp{@{1,2,3@}} is a three-element array of | |
5920 | integers, @samp{@{@{1,2@}, @{3,4@}, @{5,6@}@}} is a three-by-two array, | |
5921 | and @samp{@{&"hi", &"there", &"fred"@}} is a three-element array of pointers. | |
5922 | @end itemize | |
5923 | ||
c906108c | 5924 | @menu |
7a292a7a | 5925 | * C plus plus expressions:: |
c906108c | 5926 | * C Defaults:: |
c906108c | 5927 | * C Checks:: |
c906108c SS |
5928 | |
5929 | * Debugging C:: | |
5930 | @end menu | |
5931 | ||
53a5351d | 5932 | @node C plus plus expressions |
c906108c | 5933 | @subsubsection C++ expressions |
c906108c SS |
5934 | |
5935 | @cindex expressions in C++ | |
5936 | @value{GDBN} expression handling can interpret most C++ expressions. | |
5937 | ||
c906108c SS |
5938 | @cindex C++ support, not in @sc{coff} |
5939 | @cindex @sc{coff} versus C++ | |
5940 | @cindex C++ and object formats | |
5941 | @cindex object formats and C++ | |
5942 | @cindex a.out and C++ | |
5943 | @cindex @sc{ecoff} and C++ | |
5944 | @cindex @sc{xcoff} and C++ | |
5945 | @cindex @sc{elf}/stabs and C++ | |
5946 | @cindex @sc{elf}/@sc{dwarf} and C++ | |
5947 | @c FIXME!! GDB may eventually be able to debug C++ using DWARF; check | |
5948 | @c periodically whether this has happened... | |
5949 | @quotation | |
5950 | @emph{Warning:} @value{GDBN} can only debug C++ code if you use the | |
5951 | proper compiler. Typically, C++ debugging depends on the use of | |
5952 | additional debugging information in the symbol table, and thus requires | |
5953 | special support. In particular, if your compiler generates a.out, MIPS | |
5954 | @sc{ecoff}, RS/6000 @sc{xcoff}, or @sc{elf} with stabs extensions to the | |
5955 | symbol table, these facilities are all available. (With @sc{gnu} CC, | |
5956 | you can use the @samp{-gstabs} option to request stabs debugging | |
5957 | extensions explicitly.) Where the object code format is standard | |
5958 | @sc{coff} or @sc{dwarf} in @sc{elf}, on the other hand, most of the C++ | |
5959 | support in @value{GDBN} does @emph{not} work. | |
5960 | @end quotation | |
c906108c SS |
5961 | |
5962 | @enumerate | |
5963 | ||
5964 | @cindex member functions | |
5965 | @item | |
5966 | Member function calls are allowed; you can use expressions like | |
5967 | ||
5968 | @example | |
5969 | count = aml->GetOriginal(x, y) | |
5970 | @end example | |
5971 | ||
5972 | @kindex this | |
5973 | @cindex namespace in C++ | |
5974 | @item | |
5975 | While a member function is active (in the selected stack frame), your | |
5976 | expressions have the same namespace available as the member function; | |
5977 | that is, @value{GDBN} allows implicit references to the class instance | |
5978 | pointer @code{this} following the same rules as C++. | |
5979 | ||
c906108c | 5980 | @cindex call overloaded functions |
d4f3574e | 5981 | @cindex overloaded functions, calling |
c906108c SS |
5982 | @cindex type conversions in C++ |
5983 | @item | |
5984 | You can call overloaded functions; @value{GDBN} resolves the function | |
d4f3574e | 5985 | call to the right definition, with some restrictions. @value{GDBN} does not |
c906108c SS |
5986 | perform overload resolution involving user-defined type conversions, |
5987 | calls to constructors, or instantiations of templates that do not exist | |
5988 | in the program. It also cannot handle ellipsis argument lists or | |
5989 | default arguments. | |
5990 | ||
5991 | It does perform integral conversions and promotions, floating-point | |
5992 | promotions, arithmetic conversions, pointer conversions, conversions of | |
5993 | class objects to base classes, and standard conversions such as those of | |
5994 | functions or arrays to pointers; it requires an exact match on the | |
5995 | number of function arguments. | |
5996 | ||
5997 | Overload resolution is always performed, unless you have specified | |
5998 | @code{set overload-resolution off}. @xref{Debugging C plus plus, | |
5999 | ,@value{GDBN} features for C++}. | |
6000 | ||
d4f3574e | 6001 | You must specify @code{set overload-resolution off} in order to use an |
c906108c SS |
6002 | explicit function signature to call an overloaded function, as in |
6003 | @smallexample | |
6004 | p 'foo(char,int)'('x', 13) | |
6005 | @end smallexample | |
d4f3574e | 6006 | |
c906108c | 6007 | The @value{GDBN} command-completion facility can simplify this; |
d4f3574e | 6008 | see @ref{Completion, ,Command completion}. |
c906108c | 6009 | |
c906108c SS |
6010 | @cindex reference declarations |
6011 | @item | |
6012 | @value{GDBN} understands variables declared as C++ references; you can use | |
6013 | them in expressions just as you do in C++ source---they are automatically | |
6014 | dereferenced. | |
6015 | ||
6016 | In the parameter list shown when @value{GDBN} displays a frame, the values of | |
6017 | reference variables are not displayed (unlike other variables); this | |
6018 | avoids clutter, since references are often used for large structures. | |
6019 | The @emph{address} of a reference variable is always shown, unless | |
6020 | you have specified @samp{set print address off}. | |
6021 | ||
6022 | @item | |
6023 | @value{GDBN} supports the C++ name resolution operator @code{::}---your | |
6024 | expressions can use it just as expressions in your program do. Since | |
6025 | one scope may be defined in another, you can use @code{::} repeatedly if | |
6026 | necessary, for example in an expression like | |
6027 | @samp{@var{scope1}::@var{scope2}::@var{name}}. @value{GDBN} also allows | |
6028 | resolving name scope by reference to source files, in both C and C++ | |
6029 | debugging (@pxref{Variables, ,Program variables}). | |
6030 | @end enumerate | |
6031 | ||
53a5351d JM |
6032 | In addition, when used with HP's C++ compiler, @value{GDBN} supports |
6033 | calling virtual functions correctly, printing out virtual bases of | |
6034 | objects, calling functions in a base subobject, casting objects, and | |
6035 | invoking user-defined operators. | |
c906108c | 6036 | |
53a5351d | 6037 | @node C Defaults |
c906108c | 6038 | @subsubsection C and C++ defaults |
7a292a7a | 6039 | |
c906108c SS |
6040 | @cindex C and C++ defaults |
6041 | ||
c906108c SS |
6042 | If you allow @value{GDBN} to set type and range checking automatically, they |
6043 | both default to @code{off} whenever the working language changes to | |
6044 | C or C++. This happens regardless of whether you or @value{GDBN} | |
6045 | selects the working language. | |
c906108c SS |
6046 | |
6047 | If you allow @value{GDBN} to set the language automatically, it | |
6048 | recognizes source files whose names end with @file{.c}, @file{.C}, or | |
6049 | @file{.cc}, etc, and when @value{GDBN} enters code compiled from one of | |
6050 | these files, it sets the working language to C or C++. | |
6051 | @xref{Automatically, ,Having @value{GDBN} infer the source language}, | |
6052 | for further details. | |
6053 | ||
c906108c SS |
6054 | @c Type checking is (a) primarily motivated by Modula-2, and (b) |
6055 | @c unimplemented. If (b) changes, it might make sense to let this node | |
6056 | @c appear even if Mod-2 does not, but meanwhile ignore it. roland 16jul93. | |
7a292a7a | 6057 | |
53a5351d | 6058 | @node C Checks |
c906108c | 6059 | @subsubsection C and C++ type and range checks |
7a292a7a | 6060 | |
c906108c SS |
6061 | @cindex C and C++ checks |
6062 | ||
6063 | By default, when @value{GDBN} parses C or C++ expressions, type checking | |
6064 | is not used. However, if you turn type checking on, @value{GDBN} | |
6065 | considers two variables type equivalent if: | |
6066 | ||
6067 | @itemize @bullet | |
6068 | @item | |
6069 | The two variables are structured and have the same structure, union, or | |
6070 | enumerated tag. | |
6071 | ||
6072 | @item | |
6073 | The two variables have the same type name, or types that have been | |
6074 | declared equivalent through @code{typedef}. | |
6075 | ||
6076 | @ignore | |
6077 | @c leaving this out because neither J Gilmore nor R Pesch understand it. | |
6078 | @c FIXME--beers? | |
6079 | @item | |
6080 | The two @code{struct}, @code{union}, or @code{enum} variables are | |
6081 | declared in the same declaration. (Note: this may not be true for all C | |
6082 | compilers.) | |
6083 | @end ignore | |
6084 | @end itemize | |
6085 | ||
6086 | Range checking, if turned on, is done on mathematical operations. Array | |
6087 | indices are not checked, since they are often used to index a pointer | |
6088 | that is not itself an array. | |
c906108c | 6089 | |
53a5351d | 6090 | @node Debugging C |
c906108c | 6091 | @subsubsection @value{GDBN} and C |
c906108c SS |
6092 | |
6093 | The @code{set print union} and @code{show print union} commands apply to | |
6094 | the @code{union} type. When set to @samp{on}, any @code{union} that is | |
7a292a7a SS |
6095 | inside a @code{struct} or @code{class} is also printed. Otherwise, it |
6096 | appears as @samp{@{...@}}. | |
c906108c SS |
6097 | |
6098 | The @code{@@} operator aids in the debugging of dynamic arrays, formed | |
6099 | with pointers and a memory allocation function. @xref{Expressions, | |
6100 | ,Expressions}. | |
6101 | ||
c906108c SS |
6102 | @menu |
6103 | * Debugging C plus plus:: | |
6104 | @end menu | |
6105 | ||
53a5351d | 6106 | @node Debugging C plus plus |
c906108c | 6107 | @subsubsection @value{GDBN} features for C++ |
c906108c SS |
6108 | |
6109 | @cindex commands for C++ | |
7a292a7a | 6110 | |
c906108c SS |
6111 | Some @value{GDBN} commands are particularly useful with C++, and some are |
6112 | designed specifically for use with C++. Here is a summary: | |
6113 | ||
6114 | @table @code | |
6115 | @cindex break in overloaded functions | |
6116 | @item @r{breakpoint menus} | |
6117 | When you want a breakpoint in a function whose name is overloaded, | |
6118 | @value{GDBN} breakpoint menus help you specify which function definition | |
6119 | you want. @xref{Breakpoint Menus,,Breakpoint menus}. | |
6120 | ||
6121 | @cindex overloading in C++ | |
6122 | @item rbreak @var{regex} | |
6123 | Setting breakpoints using regular expressions is helpful for setting | |
6124 | breakpoints on overloaded functions that are not members of any special | |
6125 | classes. | |
6126 | @xref{Set Breaks, ,Setting breakpoints}. | |
6127 | ||
6128 | @cindex C++ exception handling | |
6129 | @item catch throw | |
6130 | @itemx catch catch | |
6131 | Debug C++ exception handling using these commands. @xref{Set | |
6132 | Catchpoints, , Setting catchpoints}. | |
6133 | ||
6134 | @cindex inheritance | |
6135 | @item ptype @var{typename} | |
6136 | Print inheritance relationships as well as other information for type | |
6137 | @var{typename}. | |
6138 | @xref{Symbols, ,Examining the Symbol Table}. | |
6139 | ||
6140 | @cindex C++ symbol display | |
6141 | @item set print demangle | |
6142 | @itemx show print demangle | |
6143 | @itemx set print asm-demangle | |
6144 | @itemx show print asm-demangle | |
6145 | Control whether C++ symbols display in their source form, both when | |
6146 | displaying code as C++ source and when displaying disassemblies. | |
6147 | @xref{Print Settings, ,Print settings}. | |
6148 | ||
6149 | @item set print object | |
6150 | @itemx show print object | |
6151 | Choose whether to print derived (actual) or declared types of objects. | |
6152 | @xref{Print Settings, ,Print settings}. | |
6153 | ||
6154 | @item set print vtbl | |
6155 | @itemx show print vtbl | |
6156 | Control the format for printing virtual function tables. | |
6157 | @xref{Print Settings, ,Print settings}. | |
c906108c SS |
6158 | (The @code{vtbl} commands do not work on programs compiled with the HP |
6159 | ANSI C++ compiler (@code{aCC}).) | |
6160 | ||
6161 | @kindex set overload-resolution | |
d4f3574e | 6162 | @cindex overloaded functions, overload resolution |
c906108c SS |
6163 | @item set overload-resolution on |
6164 | Enable overload resolution for C++ expression evaluation. The default | |
6165 | is on. For overloaded functions, @value{GDBN} evaluates the arguments | |
6166 | and searches for a function whose signature matches the argument types, | |
d4f3574e SS |
6167 | using the standard C++ conversion rules (see @ref{C plus plus expressions, ,C++ |
6168 | expressions}, for details). If it cannot find a match, it emits a | |
c906108c SS |
6169 | message. |
6170 | ||
6171 | @item set overload-resolution off | |
6172 | Disable overload resolution for C++ expression evaluation. For | |
6173 | overloaded functions that are not class member functions, @value{GDBN} | |
6174 | chooses the first function of the specified name that it finds in the | |
6175 | symbol table, whether or not its arguments are of the correct type. For | |
6176 | overloaded functions that are class member functions, @value{GDBN} | |
6177 | searches for a function whose signature @emph{exactly} matches the | |
6178 | argument types. | |
c906108c SS |
6179 | |
6180 | @item @r{Overloaded symbol names} | |
6181 | You can specify a particular definition of an overloaded symbol, using | |
6182 | the same notation that is used to declare such symbols in C++: type | |
6183 | @code{@var{symbol}(@var{types})} rather than just @var{symbol}. You can | |
6184 | also use the @value{GDBN} command-line word completion facilities to list the | |
6185 | available choices, or to finish the type list for you. | |
6186 | @xref{Completion,, Command completion}, for details on how to do this. | |
6187 | @end table | |
c906108c | 6188 | |
53a5351d | 6189 | @node Modula-2 |
c906108c | 6190 | @subsection Modula-2 |
7a292a7a | 6191 | |
d4f3574e | 6192 | @cindex Modula-2, @value{GDBN} support |
c906108c SS |
6193 | |
6194 | The extensions made to @value{GDBN} to support Modula-2 only support | |
6195 | output from the @sc{gnu} Modula-2 compiler (which is currently being | |
6196 | developed). Other Modula-2 compilers are not currently supported, and | |
6197 | attempting to debug executables produced by them is most likely | |
6198 | to give an error as @value{GDBN} reads in the executable's symbol | |
6199 | table. | |
6200 | ||
6201 | @cindex expressions in Modula-2 | |
6202 | @menu | |
6203 | * M2 Operators:: Built-in operators | |
6204 | * Built-In Func/Proc:: Built-in functions and procedures | |
6205 | * M2 Constants:: Modula-2 constants | |
6206 | * M2 Defaults:: Default settings for Modula-2 | |
6207 | * Deviations:: Deviations from standard Modula-2 | |
6208 | * M2 Checks:: Modula-2 type and range checks | |
6209 | * M2 Scope:: The scope operators @code{::} and @code{.} | |
6210 | * GDB/M2:: @value{GDBN} and Modula-2 | |
6211 | @end menu | |
6212 | ||
53a5351d | 6213 | @node M2 Operators |
c906108c SS |
6214 | @subsubsection Operators |
6215 | @cindex Modula-2 operators | |
6216 | ||
6217 | Operators must be defined on values of specific types. For instance, | |
6218 | @code{+} is defined on numbers, but not on structures. Operators are | |
6219 | often defined on groups of types. For the purposes of Modula-2, the | |
6220 | following definitions hold: | |
6221 | ||
6222 | @itemize @bullet | |
6223 | ||
6224 | @item | |
6225 | @emph{Integral types} consist of @code{INTEGER}, @code{CARDINAL}, and | |
6226 | their subranges. | |
6227 | ||
6228 | @item | |
6229 | @emph{Character types} consist of @code{CHAR} and its subranges. | |
6230 | ||
6231 | @item | |
6232 | @emph{Floating-point types} consist of @code{REAL}. | |
6233 | ||
6234 | @item | |
6235 | @emph{Pointer types} consist of anything declared as @code{POINTER TO | |
6236 | @var{type}}. | |
6237 | ||
6238 | @item | |
6239 | @emph{Scalar types} consist of all of the above. | |
6240 | ||
6241 | @item | |
6242 | @emph{Set types} consist of @code{SET} and @code{BITSET} types. | |
6243 | ||
6244 | @item | |
6245 | @emph{Boolean types} consist of @code{BOOLEAN}. | |
6246 | @end itemize | |
6247 | ||
6248 | @noindent | |
6249 | The following operators are supported, and appear in order of | |
6250 | increasing precedence: | |
6251 | ||
6252 | @table @code | |
6253 | @item , | |
6254 | Function argument or array index separator. | |
6255 | ||
6256 | @item := | |
6257 | Assignment. The value of @var{var} @code{:=} @var{value} is | |
6258 | @var{value}. | |
6259 | ||
6260 | @item <@r{, }> | |
6261 | Less than, greater than on integral, floating-point, or enumerated | |
6262 | types. | |
6263 | ||
6264 | @item <=@r{, }>= | |
6265 | Less than, greater than, less than or equal to, greater than or equal to | |
6266 | on integral, floating-point and enumerated types, or set inclusion on | |
6267 | set types. Same precedence as @code{<}. | |
6268 | ||
6269 | @item =@r{, }<>@r{, }# | |
6270 | Equality and two ways of expressing inequality, valid on scalar types. | |
6271 | Same precedence as @code{<}. In @value{GDBN} scripts, only @code{<>} is | |
6272 | available for inequality, since @code{#} conflicts with the script | |
6273 | comment character. | |
6274 | ||
6275 | @item IN | |
6276 | Set membership. Defined on set types and the types of their members. | |
6277 | Same precedence as @code{<}. | |
6278 | ||
6279 | @item OR | |
6280 | Boolean disjunction. Defined on boolean types. | |
6281 | ||
6282 | @item AND@r{, }& | |
d4f3574e | 6283 | Boolean conjunction. Defined on boolean types. |
c906108c SS |
6284 | |
6285 | @item @@ | |
6286 | The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}). | |
6287 | ||
6288 | @item +@r{, }- | |
6289 | Addition and subtraction on integral and floating-point types, or union | |
6290 | and difference on set types. | |
6291 | ||
6292 | @item * | |
6293 | Multiplication on integral and floating-point types, or set intersection | |
6294 | on set types. | |
6295 | ||
6296 | @item / | |
6297 | Division on floating-point types, or symmetric set difference on set | |
6298 | types. Same precedence as @code{*}. | |
6299 | ||
6300 | @item DIV@r{, }MOD | |
6301 | Integer division and remainder. Defined on integral types. Same | |
6302 | precedence as @code{*}. | |
6303 | ||
6304 | @item - | |
6305 | Negative. Defined on @code{INTEGER} and @code{REAL} data. | |
6306 | ||
6307 | @item ^ | |
6308 | Pointer dereferencing. Defined on pointer types. | |
6309 | ||
6310 | @item NOT | |
6311 | Boolean negation. Defined on boolean types. Same precedence as | |
6312 | @code{^}. | |
6313 | ||
6314 | @item . | |
6315 | @code{RECORD} field selector. Defined on @code{RECORD} data. Same | |
6316 | precedence as @code{^}. | |
6317 | ||
6318 | @item [] | |
6319 | Array indexing. Defined on @code{ARRAY} data. Same precedence as @code{^}. | |
6320 | ||
6321 | @item () | |
6322 | Procedure argument list. Defined on @code{PROCEDURE} objects. Same precedence | |
6323 | as @code{^}. | |
6324 | ||
6325 | @item ::@r{, }. | |
6326 | @value{GDBN} and Modula-2 scope operators. | |
6327 | @end table | |
6328 | ||
6329 | @quotation | |
6330 | @emph{Warning:} Sets and their operations are not yet supported, so @value{GDBN} | |
6331 | treats the use of the operator @code{IN}, or the use of operators | |
6332 | @code{+}, @code{-}, @code{*}, @code{/}, @code{=}, , @code{<>}, @code{#}, | |
6333 | @code{<=}, and @code{>=} on sets as an error. | |
6334 | @end quotation | |
6335 | ||
6336 | @cindex Modula-2 built-ins | |
53a5351d | 6337 | @node Built-In Func/Proc |
c906108c SS |
6338 | @subsubsection Built-in functions and procedures |
6339 | ||
6340 | Modula-2 also makes available several built-in procedures and functions. | |
6341 | In describing these, the following metavariables are used: | |
6342 | ||
6343 | @table @var | |
6344 | ||
6345 | @item a | |
6346 | represents an @code{ARRAY} variable. | |
6347 | ||
6348 | @item c | |
6349 | represents a @code{CHAR} constant or variable. | |
6350 | ||
6351 | @item i | |
6352 | represents a variable or constant of integral type. | |
6353 | ||
6354 | @item m | |
6355 | represents an identifier that belongs to a set. Generally used in the | |
6356 | same function with the metavariable @var{s}. The type of @var{s} should | |
6357 | be @code{SET OF @var{mtype}} (where @var{mtype} is the type of @var{m}). | |
6358 | ||
6359 | @item n | |
6360 | represents a variable or constant of integral or floating-point type. | |
6361 | ||
6362 | @item r | |
6363 | represents a variable or constant of floating-point type. | |
6364 | ||
6365 | @item t | |
6366 | represents a type. | |
6367 | ||
6368 | @item v | |
6369 | represents a variable. | |
6370 | ||
6371 | @item x | |
6372 | represents a variable or constant of one of many types. See the | |
6373 | explanation of the function for details. | |
6374 | @end table | |
6375 | ||
6376 | All Modula-2 built-in procedures also return a result, described below. | |
6377 | ||
6378 | @table @code | |
6379 | @item ABS(@var{n}) | |
6380 | Returns the absolute value of @var{n}. | |
6381 | ||
6382 | @item CAP(@var{c}) | |
6383 | If @var{c} is a lower case letter, it returns its upper case | |
c3f6f71d | 6384 | equivalent, otherwise it returns its argument. |
c906108c SS |
6385 | |
6386 | @item CHR(@var{i}) | |
6387 | Returns the character whose ordinal value is @var{i}. | |
6388 | ||
6389 | @item DEC(@var{v}) | |
c3f6f71d | 6390 | Decrements the value in the variable @var{v} by one. Returns the new value. |
c906108c SS |
6391 | |
6392 | @item DEC(@var{v},@var{i}) | |
6393 | Decrements the value in the variable @var{v} by @var{i}. Returns the | |
6394 | new value. | |
6395 | ||
6396 | @item EXCL(@var{m},@var{s}) | |
6397 | Removes the element @var{m} from the set @var{s}. Returns the new | |
6398 | set. | |
6399 | ||
6400 | @item FLOAT(@var{i}) | |
6401 | Returns the floating point equivalent of the integer @var{i}. | |
6402 | ||
6403 | @item HIGH(@var{a}) | |
6404 | Returns the index of the last member of @var{a}. | |
6405 | ||
6406 | @item INC(@var{v}) | |
c3f6f71d | 6407 | Increments the value in the variable @var{v} by one. Returns the new value. |
c906108c SS |
6408 | |
6409 | @item INC(@var{v},@var{i}) | |
6410 | Increments the value in the variable @var{v} by @var{i}. Returns the | |
6411 | new value. | |
6412 | ||
6413 | @item INCL(@var{m},@var{s}) | |
6414 | Adds the element @var{m} to the set @var{s} if it is not already | |
6415 | there. Returns the new set. | |
6416 | ||
6417 | @item MAX(@var{t}) | |
6418 | Returns the maximum value of the type @var{t}. | |
6419 | ||
6420 | @item MIN(@var{t}) | |
6421 | Returns the minimum value of the type @var{t}. | |
6422 | ||
6423 | @item ODD(@var{i}) | |
6424 | Returns boolean TRUE if @var{i} is an odd number. | |
6425 | ||
6426 | @item ORD(@var{x}) | |
6427 | Returns the ordinal value of its argument. For example, the ordinal | |
c3f6f71d JM |
6428 | value of a character is its @sc{ascii} value (on machines supporting the |
6429 | @sc{ascii} character set). @var{x} must be of an ordered type, which include | |
c906108c SS |
6430 | integral, character and enumerated types. |
6431 | ||
6432 | @item SIZE(@var{x}) | |
6433 | Returns the size of its argument. @var{x} can be a variable or a type. | |
6434 | ||
6435 | @item TRUNC(@var{r}) | |
6436 | Returns the integral part of @var{r}. | |
6437 | ||
6438 | @item VAL(@var{t},@var{i}) | |
6439 | Returns the member of the type @var{t} whose ordinal value is @var{i}. | |
6440 | @end table | |
6441 | ||
6442 | @quotation | |
6443 | @emph{Warning:} Sets and their operations are not yet supported, so | |
6444 | @value{GDBN} treats the use of procedures @code{INCL} and @code{EXCL} as | |
6445 | an error. | |
6446 | @end quotation | |
6447 | ||
6448 | @cindex Modula-2 constants | |
53a5351d | 6449 | @node M2 Constants |
c906108c SS |
6450 | @subsubsection Constants |
6451 | ||
6452 | @value{GDBN} allows you to express the constants of Modula-2 in the following | |
6453 | ways: | |
6454 | ||
6455 | @itemize @bullet | |
6456 | ||
6457 | @item | |
6458 | Integer constants are simply a sequence of digits. When used in an | |
6459 | expression, a constant is interpreted to be type-compatible with the | |
6460 | rest of the expression. Hexadecimal integers are specified by a | |
6461 | trailing @samp{H}, and octal integers by a trailing @samp{B}. | |
6462 | ||
6463 | @item | |
6464 | Floating point constants appear as a sequence of digits, followed by a | |
6465 | decimal point and another sequence of digits. An optional exponent can | |
6466 | then be specified, in the form @samp{E@r{[}+@r{|}-@r{]}@var{nnn}}, where | |
6467 | @samp{@r{[}+@r{|}-@r{]}@var{nnn}} is the desired exponent. All of the | |
6468 | digits of the floating point constant must be valid decimal (base 10) | |
6469 | digits. | |
6470 | ||
6471 | @item | |
6472 | Character constants consist of a single character enclosed by a pair of | |
6473 | like quotes, either single (@code{'}) or double (@code{"}). They may | |
c3f6f71d | 6474 | also be expressed by their ordinal value (their @sc{ascii} value, usually) |
c906108c SS |
6475 | followed by a @samp{C}. |
6476 | ||
6477 | @item | |
6478 | String constants consist of a sequence of characters enclosed by a | |
6479 | pair of like quotes, either single (@code{'}) or double (@code{"}). | |
6480 | Escape sequences in the style of C are also allowed. @xref{C | |
6481 | Constants, ,C and C++ constants}, for a brief explanation of escape | |
6482 | sequences. | |
6483 | ||
6484 | @item | |
6485 | Enumerated constants consist of an enumerated identifier. | |
6486 | ||
6487 | @item | |
6488 | Boolean constants consist of the identifiers @code{TRUE} and | |
6489 | @code{FALSE}. | |
6490 | ||
6491 | @item | |
6492 | Pointer constants consist of integral values only. | |
6493 | ||
6494 | @item | |
6495 | Set constants are not yet supported. | |
6496 | @end itemize | |
6497 | ||
53a5351d | 6498 | @node M2 Defaults |
c906108c SS |
6499 | @subsubsection Modula-2 defaults |
6500 | @cindex Modula-2 defaults | |
6501 | ||
6502 | If type and range checking are set automatically by @value{GDBN}, they | |
6503 | both default to @code{on} whenever the working language changes to | |
d4f3574e | 6504 | Modula-2. This happens regardless of whether you or @value{GDBN} |
c906108c SS |
6505 | selected the working language. |
6506 | ||
6507 | If you allow @value{GDBN} to set the language automatically, then entering | |
6508 | code compiled from a file whose name ends with @file{.mod} sets the | |
d4f3574e | 6509 | working language to Modula-2. @xref{Automatically, ,Having @value{GDBN} set |
c906108c SS |
6510 | the language automatically}, for further details. |
6511 | ||
53a5351d | 6512 | @node Deviations |
c906108c SS |
6513 | @subsubsection Deviations from standard Modula-2 |
6514 | @cindex Modula-2, deviations from | |
6515 | ||
6516 | A few changes have been made to make Modula-2 programs easier to debug. | |
6517 | This is done primarily via loosening its type strictness: | |
6518 | ||
6519 | @itemize @bullet | |
6520 | @item | |
6521 | Unlike in standard Modula-2, pointer constants can be formed by | |
6522 | integers. This allows you to modify pointer variables during | |
6523 | debugging. (In standard Modula-2, the actual address contained in a | |
6524 | pointer variable is hidden from you; it can only be modified | |
6525 | through direct assignment to another pointer variable or expression that | |
6526 | returned a pointer.) | |
6527 | ||
6528 | @item | |
6529 | C escape sequences can be used in strings and characters to represent | |
6530 | non-printable characters. @value{GDBN} prints out strings with these | |
6531 | escape sequences embedded. Single non-printable characters are | |
6532 | printed using the @samp{CHR(@var{nnn})} format. | |
6533 | ||
6534 | @item | |
6535 | The assignment operator (@code{:=}) returns the value of its right-hand | |
6536 | argument. | |
6537 | ||
6538 | @item | |
6539 | All built-in procedures both modify @emph{and} return their argument. | |
6540 | @end itemize | |
6541 | ||
53a5351d | 6542 | @node M2 Checks |
c906108c SS |
6543 | @subsubsection Modula-2 type and range checks |
6544 | @cindex Modula-2 checks | |
6545 | ||
6546 | @quotation | |
6547 | @emph{Warning:} in this release, @value{GDBN} does not yet perform type or | |
6548 | range checking. | |
6549 | @end quotation | |
6550 | @c FIXME remove warning when type/range checks added | |
6551 | ||
6552 | @value{GDBN} considers two Modula-2 variables type equivalent if: | |
6553 | ||
6554 | @itemize @bullet | |
6555 | @item | |
6556 | They are of types that have been declared equivalent via a @code{TYPE | |
6557 | @var{t1} = @var{t2}} statement | |
6558 | ||
6559 | @item | |
6560 | They have been declared on the same line. (Note: This is true of the | |
6561 | @sc{gnu} Modula-2 compiler, but it may not be true of other compilers.) | |
6562 | @end itemize | |
6563 | ||
6564 | As long as type checking is enabled, any attempt to combine variables | |
6565 | whose types are not equivalent is an error. | |
6566 | ||
6567 | Range checking is done on all mathematical operations, assignment, array | |
6568 | index bounds, and all built-in functions and procedures. | |
6569 | ||
53a5351d | 6570 | @node M2 Scope |
c906108c SS |
6571 | @subsubsection The scope operators @code{::} and @code{.} |
6572 | @cindex scope | |
6573 | @kindex . | |
6574 | @cindex colon, doubled as scope operator | |
6575 | @ifinfo | |
d4f3574e | 6576 | @kindex colon-colon@r{, in Modula-2} |
c906108c SS |
6577 | @c Info cannot handle :: but TeX can. |
6578 | @end ifinfo | |
6579 | @iftex | |
6580 | @kindex :: | |
6581 | @end iftex | |
6582 | ||
6583 | There are a few subtle differences between the Modula-2 scope operator | |
6584 | (@code{.}) and the @value{GDBN} scope operator (@code{::}). The two have | |
6585 | similar syntax: | |
6586 | ||
6587 | @example | |
6588 | ||
6589 | @var{module} . @var{id} | |
6590 | @var{scope} :: @var{id} | |
6591 | @end example | |
6592 | ||
6593 | @noindent | |
6594 | where @var{scope} is the name of a module or a procedure, | |
6595 | @var{module} the name of a module, and @var{id} is any declared | |
6596 | identifier within your program, except another module. | |
6597 | ||
6598 | Using the @code{::} operator makes @value{GDBN} search the scope | |
6599 | specified by @var{scope} for the identifier @var{id}. If it is not | |
6600 | found in the specified scope, then @value{GDBN} searches all scopes | |
6601 | enclosing the one specified by @var{scope}. | |
6602 | ||
6603 | Using the @code{.} operator makes @value{GDBN} search the current scope for | |
6604 | the identifier specified by @var{id} that was imported from the | |
6605 | definition module specified by @var{module}. With this operator, it is | |
6606 | an error if the identifier @var{id} was not imported from definition | |
6607 | module @var{module}, or if @var{id} is not an identifier in | |
6608 | @var{module}. | |
6609 | ||
53a5351d | 6610 | @node GDB/M2 |
c906108c SS |
6611 | @subsubsection @value{GDBN} and Modula-2 |
6612 | ||
6613 | Some @value{GDBN} commands have little use when debugging Modula-2 programs. | |
6614 | Five subcommands of @code{set print} and @code{show print} apply | |
6615 | specifically to C and C++: @samp{vtbl}, @samp{demangle}, | |
6616 | @samp{asm-demangle}, @samp{object}, and @samp{union}. The first four | |
6617 | apply to C++, and the last to the C @code{union} type, which has no direct | |
6618 | analogue in Modula-2. | |
6619 | ||
6620 | The @code{@@} operator (@pxref{Expressions, ,Expressions}), while available | |
d4f3574e | 6621 | with any language, is not useful with Modula-2. Its |
c906108c SS |
6622 | intent is to aid the debugging of @dfn{dynamic arrays}, which cannot be |
6623 | created in Modula-2 as they can in C or C++. However, because an | |
6624 | address can be specified by an integral constant, the construct | |
d4f3574e | 6625 | @samp{@{@var{type}@}@var{adrexp}} is still useful. |
c906108c SS |
6626 | |
6627 | @cindex @code{#} in Modula-2 | |
6628 | In @value{GDBN} scripts, the Modula-2 inequality operator @code{#} is | |
6629 | interpreted as the beginning of a comment. Use @code{<>} instead. | |
c906108c | 6630 | |
53a5351d | 6631 | @node Chill |
cce74817 JM |
6632 | @subsection Chill |
6633 | ||
6634 | The extensions made to @value{GDBN} to support Chill only support output | |
d4f3574e | 6635 | from the @sc{gnu} Chill compiler. Other Chill compilers are not currently |
cce74817 JM |
6636 | supported, and attempting to debug executables produced by them is most |
6637 | likely to give an error as @value{GDBN} reads in the executable's symbol | |
6638 | table. | |
6639 | ||
d4f3574e SS |
6640 | @c This used to say "... following Chill related topics ...", but since |
6641 | @c menus are not shown in the printed manual, it would look awkward. | |
6642 | This section covers the Chill related topics and the features | |
cce74817 JM |
6643 | of @value{GDBN} which support these topics. |
6644 | ||
6645 | @menu | |
104c1213 JM |
6646 | * How modes are displayed:: How modes are displayed |
6647 | * Locations:: Locations and their accesses | |
cce74817 | 6648 | * Values and their Operations:: Values and their Operations |
53a5351d JM |
6649 | * Chill type and range checks:: |
6650 | * Chill defaults:: | |
cce74817 JM |
6651 | @end menu |
6652 | ||
6653 | @node How modes are displayed | |
6654 | @subsubsection How modes are displayed | |
6655 | ||
6656 | The Chill Datatype- (Mode) support of @value{GDBN} is directly related | |
d4f3574e | 6657 | with the functionality of the @sc{gnu} Chill compiler, and therefore deviates |
cce74817 JM |
6658 | slightly from the standard specification of the Chill language. The |
6659 | provided modes are: | |
d4f3574e SS |
6660 | |
6661 | @c FIXME: this @table's contents effectively disable @code by using @r | |
6662 | @c on every @item. So why does it need @code? | |
cce74817 JM |
6663 | @table @code |
6664 | @item @r{@emph{Discrete modes:}} | |
6665 | @itemize @bullet | |
6666 | @item | |
6667 | @emph{Integer Modes} which are predefined by @code{BYTE, UBYTE, INT, | |
6668 | UINT, LONG, ULONG}, | |
6669 | @item | |
6670 | @emph{Boolean Mode} which is predefined by @code{BOOL}, | |
6671 | @item | |
6672 | @emph{Character Mode} which is predefined by @code{CHAR}, | |
6673 | @item | |
6674 | @emph{Set Mode} which is displayed by the keyword @code{SET}. | |
6675 | @smallexample | |
6676 | (@value{GDBP}) ptype x | |
6677 | type = SET (karli = 10, susi = 20, fritzi = 100) | |
6678 | @end smallexample | |
6679 | If the type is an unnumbered set the set element values are omitted. | |
6680 | @item | |
6681 | @emph{Range Mode} which is displayed by @code{type = <basemode> | |
6682 | (<lower bound> : <upper bound>)}, where @code{<lower bound>, <upper | |
6683 | bound>} can be of any discrete literal expression (e.g. set element | |
6684 | names). | |
6685 | @end itemize | |
6686 | ||
6687 | @item @r{@emph{Powerset Mode:}} | |
6688 | A Powerset Mode is displayed by the keyword @code{POWERSET} followed by | |
d4f3574e | 6689 | the member mode of the powerset. The member mode can be any discrete mode. |
cce74817 JM |
6690 | @smallexample |
6691 | (@value{GDBP}) ptype x | |
6692 | type = POWERSET SET (egon, hugo, otto) | |
6693 | @end smallexample | |
6694 | ||
6695 | @item @r{@emph{Reference Modes:}} | |
6696 | @itemize @bullet | |
6697 | @item | |
d4f3574e | 6698 | @emph{Bound Reference Mode} which is displayed by the keyword @code{REF} |
cce74817 JM |
6699 | followed by the mode name to which the reference is bound. |
6700 | @item | |
6701 | @emph{Free Reference Mode} which is displayed by the keyword @code{PTR}. | |
6702 | @end itemize | |
6703 | ||
6704 | @item @r{@emph{Procedure mode}} | |
6705 | The procedure mode is displayed by @code{type = PROC(<parameter list>) | |
6706 | <return mode> EXCEPTIONS (<exception list>)}. The @code{<parameter | |
d4f3574e SS |
6707 | list>} is a list of the parameter modes. @code{<return mode>} indicates |
6708 | the mode of the result of the procedure if any. The exceptionlist lists | |
cce74817 JM |
6709 | all possible exceptions which can be raised by the procedure. |
6710 | ||
6711 | @ignore | |
6712 | @item @r{@emph{Instance mode}} | |
6713 | The instance mode is represented by a structure, which has a static | |
6714 | type, and is therefore not really of interest. | |
6715 | @end ignore | |
6716 | ||
6717 | @item @r{@emph{Synchronization Modes:}} | |
6718 | @itemize @bullet | |
6719 | @item | |
6720 | @emph{Event Mode} which is displayed by @code{EVENT (<event length>)}, | |
6721 | where @code{(<event length>)} is optional. | |
6722 | @item | |
6723 | @emph{Buffer Mode} which is displayed by @code{BUFFER (<buffer length>) | |
6724 | <buffer element mode>}, where @code{(<buffer length>)} is optional. | |
6725 | @end itemize | |
6726 | ||
6727 | @item @r{@emph{Timing Modes:}} | |
6728 | @itemize @bullet | |
6729 | @item | |
6730 | @emph{Duration Mode} which is predefined by @code{DURATION} | |
6731 | @item | |
6732 | @emph{Absolute Time Mode} which is predefined by @code{TIME} | |
6733 | @end itemize | |
6734 | ||
6735 | @item @r{@emph{Real Modes:}} | |
6736 | Real Modes are predefined with @code{REAL} and @code{LONG_REAL}. | |
6737 | ||
6738 | @item @r{@emph{String Modes:}} | |
6739 | @itemize @bullet | |
6740 | @item | |
6741 | @emph{Character String Mode} which is displayed by @code{CHARS(<string | |
6742 | length>)}, followed by the keyword @code{VARYING} if the String Mode is | |
6743 | a varying mode | |
6744 | @item | |
6745 | @emph{Bit String Mode} which is displayed by @code{BOOLS(<string | |
6746 | length>)}. | |
6747 | @end itemize | |
6748 | ||
6749 | @item @r{@emph{Array Mode:}} | |
6750 | The Array Mode is displayed by the keyword @code{ARRAY(<range>)} | |
6751 | followed by the element mode (which may in turn be an array mode). | |
6752 | @smallexample | |
6753 | (@value{GDBP}) ptype x | |
6754 | type = ARRAY (1:42) | |
6755 | ARRAY (1:20) | |
6756 | SET (karli = 10, susi = 20, fritzi = 100) | |
6757 | @end smallexample | |
6758 | ||
6759 | @item @r{@emph{Structure Mode}} | |
6760 | The Structure mode is displayed by the keyword @code{STRUCT(<field | |
d4f3574e SS |
6761 | list>)}. The @code{<field list>} consists of names and modes of fields |
6762 | of the structure. Variant structures have the keyword @code{CASE <field> | |
6763 | OF <variant fields> ESAC} in their field list. Since the current version | |
cce74817 JM |
6764 | of the GNU Chill compiler doesn't implement tag processing (no runtime |
6765 | checks of variant fields, and therefore no debugging info), the output | |
6766 | always displays all variant fields. | |
6767 | @smallexample | |
6768 | (@value{GDBP}) ptype str | |
6769 | type = STRUCT ( | |
6770 | as x, | |
6771 | bs x, | |
6772 | CASE bs OF | |
6773 | (karli): | |
6774 | cs a | |
6775 | (ott): | |
6776 | ds x | |
6777 | ESAC | |
6778 | ) | |
6779 | @end smallexample | |
6780 | @end table | |
6781 | ||
6782 | @node Locations | |
6783 | @subsubsection Locations and their accesses | |
6784 | ||
6785 | A location in Chill is an object which can contain values. | |
6786 | ||
6787 | A value of a location is generally accessed by the (declared) name of | |
d4f3574e SS |
6788 | the location. The output conforms to the specification of values in |
6789 | Chill programs. How values are specified | |
6790 | is the topic of the next section, @ref{Values and their Operations}. | |
cce74817 JM |
6791 | |
6792 | The pseudo-location @code{RESULT} (or @code{result}) can be used to | |
6793 | display or change the result of a currently-active procedure: | |
d4f3574e | 6794 | |
cce74817 JM |
6795 | @smallexample |
6796 | set result := EXPR | |
6797 | @end smallexample | |
d4f3574e SS |
6798 | |
6799 | @noindent | |
6800 | This does the same as the Chill action @code{RESULT EXPR} (which | |
c3f6f71d | 6801 | is not available in @value{GDBN}). |
cce74817 JM |
6802 | |
6803 | Values of reference mode locations are printed by @code{PTR(<hex | |
6804 | value>)} in case of a free reference mode, and by @code{(REF <reference | |
d4f3574e | 6805 | mode>) (<hex-value>)} in case of a bound reference. @code{<hex value>} |
cce74817 JM |
6806 | represents the address where the reference points to. To access the |
6807 | value of the location referenced by the pointer, use the dereference | |
d4f3574e | 6808 | operator @samp{->}. |
cce74817 JM |
6809 | |
6810 | Values of procedure mode locations are displayed by @code{@{ PROC | |
6811 | (<argument modes> ) <return mode> @} <address> <name of procedure | |
d4f3574e | 6812 | location>}. @code{<argument modes>} is a list of modes according to the |
cce74817 JM |
6813 | parameter specification of the procedure and @code{<address>} shows the |
6814 | address of the entry point. | |
6815 | ||
6816 | @ignore | |
6817 | Locations of instance modes are displayed just like a structure with two | |
6818 | fields specifying the @emph{process type} and the @emph{copy number} of | |
6819 | the investigated instance location@footnote{This comes from the current | |
d4f3574e SS |
6820 | implementation of instances. They are implemented as a structure (no |
6821 | na). The output should be something like @code{[<name of the process>; | |
6822 | <instance number>]}.}. The field names are @code{__proc_type} and | |
cce74817 JM |
6823 | @code{__proc_copy}. |
6824 | ||
6825 | Locations of synchronization modes are displayed like a structure with | |
6826 | the field name @code{__event_data} in case of a event mode location, and | |
6827 | like a structure with the field @code{__buffer_data} in case of a buffer | |
6828 | mode location (refer to previous paragraph). | |
6829 | ||
6830 | Structure Mode locations are printed by @code{[.<field name>: <value>, | |
d4f3574e | 6831 | ...]}. The @code{<field name>} corresponds to the structure mode |
cce74817 | 6832 | definition and the layout of @code{<value>} varies depending of the mode |
d4f3574e SS |
6833 | of the field. If the investigated structure mode location is of variant |
6834 | structure mode, the variant parts of the structure are enclosed in curled | |
6835 | braces (@samp{@{@}}). Fields enclosed by @samp{@{,@}} are residing | |
cce74817 | 6836 | on the same memory location and represent the current values of the |
d4f3574e | 6837 | memory location in their specific modes. Since no tag processing is done |
cce74817 | 6838 | all variants are displayed. A variant field is printed by |
d4f3574e | 6839 | @code{(<variant name>) = .<field name>: <value>}. (who implements the |
cce74817 JM |
6840 | stuff ???) |
6841 | @smallexample | |
6842 | (@value{GDBP}) print str1 $4 = [.as: 0, .bs: karli, .<TAG>: { (karli) = | |
6843 | [.cs: []], (susi) = [.ds: susi]}] | |
6844 | @end smallexample | |
6845 | @end ignore | |
6846 | ||
6847 | Substructures of string mode-, array mode- or structure mode-values | |
6848 | (e.g. array slices, fields of structure locations) are accessed using | |
d4f3574e SS |
6849 | certain operations which are described in the next section, @ref{Values |
6850 | and their Operations}. | |
cce74817 JM |
6851 | |
6852 | A location value may be interpreted as having a different mode using the | |
d4f3574e SS |
6853 | location conversion. This mode conversion is written as @code{<mode |
6854 | name>(<location>)}. The user has to consider that the sizes of the modes | |
6855 | have to be equal otherwise an error occurs. Furthermore, no range | |
6856 | checking of the location against the destination mode is performed, and | |
cce74817 | 6857 | therefore the result can be quite confusing. |
d4f3574e | 6858 | |
cce74817 JM |
6859 | @smallexample |
6860 | (@value{GDBP}) print int (s(3 up 4)) XXX TO be filled in !! XXX | |
6861 | @end smallexample | |
6862 | ||
6863 | @node Values and their Operations | |
6864 | @subsubsection Values and their Operations | |
6865 | ||
6866 | Values are used to alter locations, to investigate complex structures in | |
6867 | more detail or to filter relevant information out of a large amount of | |
d4f3574e SS |
6868 | data. There are several (mode dependent) operations defined which enable |
6869 | such investigations. These operations are not only applicable to | |
cce74817 | 6870 | constant values but also to locations, which can become quite useful |
d4f3574e | 6871 | when debugging complex structures. During parsing the command line |
cce74817 JM |
6872 | (e.g. evaluating an expression) @value{GDBN} treats location names as |
6873 | the values behind these locations. | |
6874 | ||
d4f3574e | 6875 | This section describes how values have to be specified and which |
cce74817 JM |
6876 | operations are legal to be used with such values. |
6877 | ||
6878 | @table @code | |
6879 | @item Literal Values | |
d4f3574e SS |
6880 | Literal values are specified in the same manner as in @sc{gnu} Chill programs. |
6881 | For detailed specification refer to the @sc{gnu} Chill implementation Manual | |
cce74817 | 6882 | chapter 1.5. |
d4f3574e SS |
6883 | @c FIXME: if the Chill Manual is a Texinfo documents, the above should |
6884 | @c be converted to a @ref. | |
cce74817 JM |
6885 | |
6886 | @ignore | |
6887 | @itemize @bullet | |
6888 | @item | |
6889 | @emph{Integer Literals} are specified in the same manner as in Chill | |
d4f3574e | 6890 | programs (refer to the Chill Standard z200/88 chpt 5.2.4.2) |
cce74817 JM |
6891 | @item |
6892 | @emph{Boolean Literals} are defined by @code{TRUE} and @code{FALSE}. | |
6893 | @item | |
6894 | @emph{Character Literals} are defined by @code{'<character>'}. (e.g. | |
6895 | @code{'M'}) | |
6896 | @item | |
6897 | @emph{Set Literals} are defined by a name which was specified in a set | |
d4f3574e SS |
6898 | mode. The value delivered by a Set Literal is the set value. This is |
6899 | comparable to an enumeration in C/C++ language. | |
cce74817 | 6900 | @item |
d4f3574e | 6901 | @emph{Emptiness Literal} is predefined by @code{NULL}. The value of the |
cce74817 JM |
6902 | emptiness literal delivers either the empty reference value, the empty |
6903 | procedure value or the empty instance value. | |
6904 | ||
6905 | @item | |
6906 | @emph{Character String Literals} are defined by a sequence of characters | |
d4f3574e | 6907 | enclosed in single- or double quotes. If a single- or double quote has |
cce74817 JM |
6908 | to be part of the string literal it has to be stuffed (specified twice). |
6909 | @item | |
6910 | @emph{Bitstring Literals} are specified in the same manner as in Chill | |
6911 | programs (refer z200/88 chpt 5.2.4.8). | |
6912 | @item | |
6913 | @emph{Floating point literals} are specified in the same manner as in | |
d4f3574e | 6914 | (gnu-)Chill programs (refer @sc{gnu} Chill implementation Manual chapter 1.5). |
cce74817 JM |
6915 | @end itemize |
6916 | @end ignore | |
6917 | ||
6918 | @item Tuple Values | |
6919 | A tuple is specified by @code{<mode name>[<tuple>]}, where @code{<mode | |
d4f3574e | 6920 | name>} can be omitted if the mode of the tuple is unambiguous. This |
cce74817 JM |
6921 | unambiguity is derived from the context of a evaluated expression. |
6922 | @code{<tuple>} can be one of the following: | |
d4f3574e | 6923 | |
cce74817 JM |
6924 | @itemize @bullet |
6925 | @item @emph{Powerset Tuple} | |
6926 | @item @emph{Array Tuple} | |
6927 | @item @emph{Structure Tuple} | |
6928 | Powerset tuples, array tuples and structure tuples are specified in the | |
d4f3574e | 6929 | same manner as in Chill programs refer to z200/88 chpt 5.2.5. |
cce74817 JM |
6930 | @end itemize |
6931 | ||
6932 | @item String Element Value | |
6933 | A string element value is specified by @code{<string value>(<index>)}, | |
d4f3574e | 6934 | where @code{<index>} is a integer expression. It delivers a character |
cce74817 JM |
6935 | value which is equivalent to the character indexed by @code{<index>} in |
6936 | the string. | |
6937 | ||
6938 | @item String Slice Value | |
6939 | A string slice value is specified by @code{<string value>(<slice | |
6940 | spec>)}, where @code{<slice spec>} can be either a range of integer | |
6941 | expressions or specified by @code{<start expr> up <size>}. | |
6942 | @code{<size>} denotes the number of elements which the slice contains. | |
6943 | The delivered value is a string value, which is part of the specified | |
6944 | string. | |
6945 | ||
6946 | @item Array Element Values | |
6947 | An array element value is specified by @code{<array value>(<expr>)} and | |
6948 | delivers a array element value of the mode of the specified array. | |
6949 | ||
6950 | @item Array Slice Values | |
6951 | An array slice is specified by @code{<array value>(<slice spec>)}, where | |
6952 | @code{<slice spec>} can be either a range specified by expressions or by | |
d4f3574e SS |
6953 | @code{<start expr> up <size>}. @code{<size>} denotes the number of |
6954 | arrayelements the slice contains. The delivered value is an array value | |
cce74817 JM |
6955 | which is part of the specified array. |
6956 | ||
6957 | @item Structure Field Values | |
6958 | A structure field value is derived by @code{<structure value>.<field | |
d4f3574e SS |
6959 | name>}, where @code{<field name>} indicates the name of a field specified |
6960 | in the mode definition of the structure. The mode of the delivered value | |
cce74817 JM |
6961 | corresponds to this mode definition in the structure definition. |
6962 | ||
6963 | @item Procedure Call Value | |
6964 | The procedure call value is derived from the return value of the | |
6965 | procedure@footnote{If a procedure call is used for instance in an | |
6966 | expression, then this procedure is called with all its side | |
d4f3574e | 6967 | effects. This can lead to confusing results if used carelessly.}. |
cce74817 | 6968 | |
d4f3574e | 6969 | Values of duration mode locations are represented by @code{ULONG} literals. |
cce74817 | 6970 | |
d4f3574e | 6971 | Values of time mode locations are represented by @code{TIME(<secs>:<nsecs>)}. |
cce74817 JM |
6972 | |
6973 | @ignore | |
6974 | This is not implemented yet: | |
6975 | @item Built-in Value | |
6976 | @noindent | |
6977 | The following built in functions are provided: | |
d4f3574e | 6978 | |
cce74817 JM |
6979 | @table @code |
6980 | @item @code{ADDR()} | |
6981 | @item @code{NUM()} | |
6982 | @item @code{PRED()} | |
6983 | @item @code{SUCC()} | |
6984 | @item @code{ABS()} | |
6985 | @item @code{CARD()} | |
6986 | @item @code{MAX()} | |
6987 | @item @code{MIN()} | |
6988 | @item @code{SIZE()} | |
6989 | @item @code{UPPER()} | |
6990 | @item @code{LOWER()} | |
6991 | @item @code{LENGTH()} | |
6992 | @item @code{SIN()} | |
6993 | @item @code{COS()} | |
6994 | @item @code{TAN()} | |
6995 | @item @code{ARCSIN()} | |
6996 | @item @code{ARCCOS()} | |
6997 | @item @code{ARCTAN()} | |
6998 | @item @code{EXP()} | |
6999 | @item @code{LN()} | |
7000 | @item @code{LOG()} | |
7001 | @item @code{SQRT()} | |
7002 | @end table | |
7003 | ||
7004 | For a detailed description refer to the GNU Chill implementation manual | |
7005 | chapter 1.6. | |
7006 | @end ignore | |
7007 | ||
7008 | @item Zero-adic Operator Value | |
7009 | The zero-adic operator value is derived from the instance value for the | |
7010 | current active process. | |
7011 | ||
7012 | @item Expression Values | |
7013 | The value delivered by an expression is the result of the evaluation of | |
d4f3574e | 7014 | the specified expression. If there are error conditions (mode |
cce74817 | 7015 | incompatibility, etc.) the evaluation of expressions is aborted with a |
d4f3574e | 7016 | corresponding error message. Expressions may be parenthesised which |
cce74817 | 7017 | causes the evaluation of this expression before any other expression |
d4f3574e | 7018 | which uses the result of the parenthesised expression. The following |
cce74817 | 7019 | operators are supported by @value{GDBN}: |
d4f3574e | 7020 | |
cce74817 JM |
7021 | @table @code |
7022 | @item @code{OR, ORIF, XOR} | |
d4f3574e SS |
7023 | @itemx @code{AND, ANDIF} |
7024 | @itemx @code{NOT} | |
cce74817 | 7025 | Logical operators defined over operands of boolean mode. |
d4f3574e | 7026 | |
cce74817 JM |
7027 | @item @code{=, /=} |
7028 | Equality and inequality operators defined over all modes. | |
d4f3574e | 7029 | |
cce74817 | 7030 | @item @code{>, >=} |
d4f3574e | 7031 | @itemx @code{<, <=} |
cce74817 | 7032 | Relational operators defined over predefined modes. |
d4f3574e | 7033 | |
cce74817 | 7034 | @item @code{+, -} |
d4f3574e | 7035 | @itemx @code{*, /, MOD, REM} |
cce74817 | 7036 | Arithmetic operators defined over predefined modes. |
d4f3574e | 7037 | |
cce74817 JM |
7038 | @item @code{-} |
7039 | Change sign operator. | |
d4f3574e | 7040 | |
cce74817 JM |
7041 | @item @code{//} |
7042 | String concatenation operator. | |
d4f3574e | 7043 | |
cce74817 JM |
7044 | @item @code{()} |
7045 | String repetition operator. | |
d4f3574e | 7046 | |
cce74817 JM |
7047 | @item @code{->} |
7048 | Referenced location operator which can be used either to take the | |
7049 | address of a location (@code{->loc}), or to dereference a reference | |
7050 | location (@code{loc->}). | |
d4f3574e | 7051 | |
cce74817 | 7052 | @item @code{OR, XOR} |
d4f3574e SS |
7053 | @itemx @code{AND} |
7054 | @itemx @code{NOT} | |
cce74817 | 7055 | Powerset and bitstring operators. |
d4f3574e | 7056 | |
cce74817 | 7057 | @item @code{>, >=} |
d4f3574e | 7058 | @itemx @code{<, <=} |
cce74817 | 7059 | Powerset inclusion operators. |
d4f3574e | 7060 | |
cce74817 JM |
7061 | @item @code{IN} |
7062 | Membership operator. | |
7063 | @end table | |
7064 | @end table | |
7065 | ||
53a5351d | 7066 | @node Chill type and range checks |
cce74817 JM |
7067 | @subsubsection Chill type and range checks |
7068 | ||
7069 | @value{GDBN} considers two Chill variables mode equivalent if the sizes | |
d4f3574e | 7070 | of the two modes are equal. This rule applies recursively to more |
cce74817 | 7071 | complex datatypes which means that complex modes are treated |
d4f3574e | 7072 | equivalent if all element modes (which also can be complex modes like |
cce74817 JM |
7073 | structures, arrays, etc.) have the same size. |
7074 | ||
7075 | Range checking is done on all mathematical operations, assignment, array | |
7076 | index bounds and all built in procedures. | |
7077 | ||
7078 | Strong type checks are forced using the @value{GDBN} command @code{set | |
d4f3574e | 7079 | check strong}. This enforces strong type and range checks on all |
cce74817 JM |
7080 | operations where Chill constructs are used (expressions, built in |
7081 | functions, etc.) in respect to the semantics as defined in the z.200 | |
7082 | language specification. | |
7083 | ||
cce74817 JM |
7084 | All checks can be disabled by the @value{GDBN} command @code{set check |
7085 | off}. | |
7086 | ||
7087 | @ignore | |
53a5351d | 7088 | @c Deviations from the Chill Standard Z200/88 |
cce74817 JM |
7089 | see last paragraph ? |
7090 | @end ignore | |
7091 | ||
53a5351d | 7092 | @node Chill defaults |
cce74817 JM |
7093 | @subsubsection Chill defaults |
7094 | ||
7095 | If type and range checking are set automatically by @value{GDBN}, they | |
7096 | both default to @code{on} whenever the working language changes to | |
d4f3574e | 7097 | Chill. This happens regardless of whether you or @value{GDBN} |
cce74817 JM |
7098 | selected the working language. |
7099 | ||
7100 | If you allow @value{GDBN} to set the language automatically, then entering | |
7101 | code compiled from a file whose name ends with @file{.ch} sets the | |
d4f3574e | 7102 | working language to Chill. @xref{Automatically, ,Having @value{GDBN} set |
cce74817 JM |
7103 | the language automatically}, for further details. |
7104 | ||
53a5351d | 7105 | @node Symbols |
c906108c SS |
7106 | @chapter Examining the Symbol Table |
7107 | ||
d4f3574e | 7108 | The commands described in this chapter allow you to inquire about the |
c906108c SS |
7109 | symbols (names of variables, functions and types) defined in your |
7110 | program. This information is inherent in the text of your program and | |
7111 | does not change as your program executes. @value{GDBN} finds it in your | |
7112 | program's symbol table, in the file indicated when you started @value{GDBN} | |
7113 | (@pxref{File Options, ,Choosing files}), or by one of the | |
7114 | file-management commands (@pxref{Files, ,Commands to specify files}). | |
7115 | ||
7116 | @cindex symbol names | |
7117 | @cindex names of symbols | |
7118 | @cindex quoting names | |
7119 | Occasionally, you may need to refer to symbols that contain unusual | |
7120 | characters, which @value{GDBN} ordinarily treats as word delimiters. The | |
7121 | most frequent case is in referring to static variables in other | |
7122 | source files (@pxref{Variables,,Program variables}). File names | |
7123 | are recorded in object files as debugging symbols, but @value{GDBN} would | |
7124 | ordinarily parse a typical file name, like @file{foo.c}, as the three words | |
7125 | @samp{foo} @samp{.} @samp{c}. To allow @value{GDBN} to recognize | |
7126 | @samp{foo.c} as a single symbol, enclose it in single quotes; for example, | |
7127 | ||
7128 | @example | |
7129 | p 'foo.c'::x | |
7130 | @end example | |
7131 | ||
7132 | @noindent | |
7133 | looks up the value of @code{x} in the scope of the file @file{foo.c}. | |
7134 | ||
7135 | @table @code | |
7136 | @kindex info address | |
7137 | @item info address @var{symbol} | |
7138 | Describe where the data for @var{symbol} is stored. For a register | |
7139 | variable, this says which register it is kept in. For a non-register | |
7140 | local variable, this prints the stack-frame offset at which the variable | |
7141 | is always stored. | |
7142 | ||
7143 | Note the contrast with @samp{print &@var{symbol}}, which does not work | |
7144 | at all for a register variable, and for a stack local variable prints | |
7145 | the exact address of the current instantiation of the variable. | |
7146 | ||
7147 | @kindex whatis | |
d4f3574e SS |
7148 | @item whatis @var{expr} |
7149 | Print the data type of expression @var{expr}. @var{expr} is not | |
c906108c SS |
7150 | actually evaluated, and any side-effecting operations (such as |
7151 | assignments or function calls) inside it do not take place. | |
7152 | @xref{Expressions, ,Expressions}. | |
7153 | ||
7154 | @item whatis | |
7155 | Print the data type of @code{$}, the last value in the value history. | |
7156 | ||
7157 | @kindex ptype | |
7158 | @item ptype @var{typename} | |
7159 | Print a description of data type @var{typename}. @var{typename} may be | |
7a292a7a SS |
7160 | the name of a type, or for C code it may have the form @samp{class |
7161 | @var{class-name}}, @samp{struct @var{struct-tag}}, @samp{union | |
7162 | @var{union-tag}} or @samp{enum @var{enum-tag}}. | |
c906108c | 7163 | |
d4f3574e | 7164 | @item ptype @var{expr} |
c906108c | 7165 | @itemx ptype |
d4f3574e | 7166 | Print a description of the type of expression @var{expr}. @code{ptype} |
c906108c SS |
7167 | differs from @code{whatis} by printing a detailed description, instead |
7168 | of just the name of the type. | |
7169 | ||
7170 | For example, for this variable declaration: | |
7171 | ||
7172 | @example | |
7173 | struct complex @{double real; double imag;@} v; | |
7174 | @end example | |
7175 | ||
7176 | @noindent | |
7177 | the two commands give this output: | |
7178 | ||
7179 | @example | |
7180 | @group | |
7181 | (@value{GDBP}) whatis v | |
7182 | type = struct complex | |
7183 | (@value{GDBP}) ptype v | |
7184 | type = struct complex @{ | |
7185 | double real; | |
7186 | double imag; | |
7187 | @} | |
7188 | @end group | |
7189 | @end example | |
7190 | ||
7191 | @noindent | |
7192 | As with @code{whatis}, using @code{ptype} without an argument refers to | |
7193 | the type of @code{$}, the last value in the value history. | |
7194 | ||
7195 | @kindex info types | |
7196 | @item info types @var{regexp} | |
7197 | @itemx info types | |
d4f3574e | 7198 | Print a brief description of all types whose names match @var{regexp} |
c906108c SS |
7199 | (or all types in your program, if you supply no argument). Each |
7200 | complete typename is matched as though it were a complete line; thus, | |
7201 | @samp{i type value} gives information on all types in your program whose | |
d4f3574e | 7202 | names include the string @code{value}, but @samp{i type ^value$} gives |
c906108c SS |
7203 | information only on types whose complete name is @code{value}. |
7204 | ||
7205 | This command differs from @code{ptype} in two ways: first, like | |
7206 | @code{whatis}, it does not print a detailed description; second, it | |
7207 | lists all source files where a type is defined. | |
7208 | ||
7209 | @kindex info source | |
7210 | @item info source | |
7211 | Show the name of the current source file---that is, the source file for | |
7212 | the function containing the current point of execution---and the language | |
7213 | it was written in. | |
7214 | ||
7215 | @kindex info sources | |
7216 | @item info sources | |
7217 | Print the names of all source files in your program for which there is | |
7218 | debugging information, organized into two lists: files whose symbols | |
7219 | have already been read, and files whose symbols will be read when needed. | |
7220 | ||
7221 | @kindex info functions | |
7222 | @item info functions | |
7223 | Print the names and data types of all defined functions. | |
7224 | ||
7225 | @item info functions @var{regexp} | |
7226 | Print the names and data types of all defined functions | |
7227 | whose names contain a match for regular expression @var{regexp}. | |
7228 | Thus, @samp{info fun step} finds all functions whose names | |
7229 | include @code{step}; @samp{info fun ^step} finds those whose names | |
7230 | start with @code{step}. | |
7231 | ||
7232 | @kindex info variables | |
7233 | @item info variables | |
7234 | Print the names and data types of all variables that are declared | |
7235 | outside of functions (i.e., excluding local variables). | |
7236 | ||
7237 | @item info variables @var{regexp} | |
7238 | Print the names and data types of all variables (except for local | |
7239 | variables) whose names contain a match for regular expression | |
7240 | @var{regexp}. | |
7241 | ||
7242 | @ignore | |
7243 | This was never implemented. | |
7244 | @kindex info methods | |
7245 | @item info methods | |
7246 | @itemx info methods @var{regexp} | |
7247 | The @code{info methods} command permits the user to examine all defined | |
7248 | methods within C++ program, or (with the @var{regexp} argument) a | |
7249 | specific set of methods found in the various C++ classes. Many | |
7250 | C++ classes provide a large number of methods. Thus, the output | |
7251 | from the @code{ptype} command can be overwhelming and hard to use. The | |
7252 | @code{info-methods} command filters the methods, printing only those | |
7253 | which match the regular-expression @var{regexp}. | |
7254 | @end ignore | |
7255 | ||
c906108c SS |
7256 | @cindex reloading symbols |
7257 | Some systems allow individual object files that make up your program to | |
7a292a7a SS |
7258 | be replaced without stopping and restarting your program. For example, |
7259 | in VxWorks you can simply recompile a defective object file and keep on | |
7260 | running. If you are running on one of these systems, you can allow | |
7261 | @value{GDBN} to reload the symbols for automatically relinked modules: | |
c906108c SS |
7262 | |
7263 | @table @code | |
7264 | @kindex set symbol-reloading | |
7265 | @item set symbol-reloading on | |
7266 | Replace symbol definitions for the corresponding source file when an | |
7267 | object file with a particular name is seen again. | |
7268 | ||
7269 | @item set symbol-reloading off | |
7270 | Do not replace symbol definitions when re-encountering object files of | |
7271 | the same name. This is the default state; if you are not running on a | |
7272 | system that permits automatically relinking modules, you should leave | |
7273 | @code{symbol-reloading} off, since otherwise @value{GDBN} may discard symbols | |
7274 | when linking large programs, that may contain several modules (from | |
7275 | different directories or libraries) with the same name. | |
7276 | ||
7277 | @kindex show symbol-reloading | |
7278 | @item show symbol-reloading | |
7279 | Show the current @code{on} or @code{off} setting. | |
7280 | @end table | |
c906108c | 7281 | |
c906108c SS |
7282 | @kindex set opaque-type-resolution |
7283 | @item set opaque-type-resolution on | |
7284 | Tell @value{GDBN} to resolve opaque types. An opaque type is a type | |
7285 | declared as a pointer to a @code{struct}, @code{class}, or | |
7286 | @code{union}---for example, @code{struct MyType *}---that is used in one | |
7287 | source file although the full declaration of @code{struct MyType} is in | |
7288 | another source file. The default is on. | |
7289 | ||
7290 | A change in the setting of this subcommand will not take effect until | |
7291 | the next time symbols for a file are loaded. | |
7292 | ||
7293 | @item set opaque-type-resolution off | |
7294 | Tell @value{GDBN} not to resolve opaque types. In this case, the type | |
7295 | is printed as follows: | |
7296 | @smallexample | |
7297 | @{<no data fields>@} | |
7298 | @end smallexample | |
7299 | ||
7300 | @kindex show opaque-type-resolution | |
7301 | @item show opaque-type-resolution | |
7302 | Show whether opaque types are resolved or not. | |
c906108c SS |
7303 | |
7304 | @kindex maint print symbols | |
7305 | @cindex symbol dump | |
7306 | @kindex maint print psymbols | |
7307 | @cindex partial symbol dump | |
7308 | @item maint print symbols @var{filename} | |
7309 | @itemx maint print psymbols @var{filename} | |
7310 | @itemx maint print msymbols @var{filename} | |
7311 | Write a dump of debugging symbol data into the file @var{filename}. | |
7312 | These commands are used to debug the @value{GDBN} symbol-reading code. Only | |
7313 | symbols with debugging data are included. If you use @samp{maint print | |
7314 | symbols}, @value{GDBN} includes all the symbols for which it has already | |
7315 | collected full details: that is, @var{filename} reflects symbols for | |
7316 | only those files whose symbols @value{GDBN} has read. You can use the | |
7317 | command @code{info sources} to find out which files these are. If you | |
7318 | use @samp{maint print psymbols} instead, the dump shows information about | |
7319 | symbols that @value{GDBN} only knows partially---that is, symbols defined in | |
7320 | files that @value{GDBN} has skimmed, but not yet read completely. Finally, | |
7321 | @samp{maint print msymbols} dumps just the minimal symbol information | |
7322 | required for each object file from which @value{GDBN} has read some symbols. | |
7323 | @xref{Files, ,Commands to specify files}, for a discussion of how | |
7324 | @value{GDBN} reads symbols (in the description of @code{symbol-file}). | |
7325 | @end table | |
7326 | ||
53a5351d | 7327 | @node Altering |
c906108c SS |
7328 | @chapter Altering Execution |
7329 | ||
7330 | Once you think you have found an error in your program, you might want to | |
7331 | find out for certain whether correcting the apparent error would lead to | |
7332 | correct results in the rest of the run. You can find the answer by | |
7333 | experiment, using the @value{GDBN} features for altering execution of the | |
7334 | program. | |
7335 | ||
7336 | For example, you can store new values into variables or memory | |
7a292a7a SS |
7337 | locations, give your program a signal, restart it at a different |
7338 | address, or even return prematurely from a function. | |
c906108c SS |
7339 | |
7340 | @menu | |
7341 | * Assignment:: Assignment to variables | |
7342 | * Jumping:: Continuing at a different address | |
c906108c | 7343 | * Signaling:: Giving your program a signal |
c906108c SS |
7344 | * Returning:: Returning from a function |
7345 | * Calling:: Calling your program's functions | |
7346 | * Patching:: Patching your program | |
7347 | @end menu | |
7348 | ||
53a5351d | 7349 | @node Assignment |
c906108c SS |
7350 | @section Assignment to variables |
7351 | ||
7352 | @cindex assignment | |
7353 | @cindex setting variables | |
7354 | To alter the value of a variable, evaluate an assignment expression. | |
7355 | @xref{Expressions, ,Expressions}. For example, | |
7356 | ||
7357 | @example | |
7358 | print x=4 | |
7359 | @end example | |
7360 | ||
7361 | @noindent | |
7362 | stores the value 4 into the variable @code{x}, and then prints the | |
7363 | value of the assignment expression (which is 4). | |
c906108c SS |
7364 | @xref{Languages, ,Using @value{GDBN} with Different Languages}, for more |
7365 | information on operators in supported languages. | |
c906108c SS |
7366 | |
7367 | @kindex set variable | |
7368 | @cindex variables, setting | |
7369 | If you are not interested in seeing the value of the assignment, use the | |
7370 | @code{set} command instead of the @code{print} command. @code{set} is | |
7371 | really the same as @code{print} except that the expression's value is | |
7372 | not printed and is not put in the value history (@pxref{Value History, | |
7373 | ,Value history}). The expression is evaluated only for its effects. | |
7374 | ||
c906108c SS |
7375 | If the beginning of the argument string of the @code{set} command |
7376 | appears identical to a @code{set} subcommand, use the @code{set | |
7377 | variable} command instead of just @code{set}. This command is identical | |
7378 | to @code{set} except for its lack of subcommands. For example, if your | |
7379 | program has a variable @code{width}, you get an error if you try to set | |
7380 | a new value with just @samp{set width=13}, because @value{GDBN} has the | |
7381 | command @code{set width}: | |
7382 | ||
7383 | @example | |
7384 | (@value{GDBP}) whatis width | |
7385 | type = double | |
7386 | (@value{GDBP}) p width | |
7387 | $4 = 13 | |
7388 | (@value{GDBP}) set width=47 | |
7389 | Invalid syntax in expression. | |
7390 | @end example | |
7391 | ||
7392 | @noindent | |
7393 | The invalid expression, of course, is @samp{=47}. In | |
7394 | order to actually set the program's variable @code{width}, use | |
7395 | ||
7396 | @example | |
7397 | (@value{GDBP}) set var width=47 | |
7398 | @end example | |
53a5351d | 7399 | |
c906108c SS |
7400 | Because the @code{set} command has many subcommands that can conflict |
7401 | with the names of program variables, it is a good idea to use the | |
7402 | @code{set variable} command instead of just @code{set}. For example, if | |
7403 | your program has a variable @code{g}, you run into problems if you try | |
7404 | to set a new value with just @samp{set g=4}, because @value{GDBN} has | |
7405 | the command @code{set gnutarget}, abbreviated @code{set g}: | |
7406 | ||
7407 | @example | |
7408 | @group | |
7409 | (@value{GDBP}) whatis g | |
7410 | type = double | |
7411 | (@value{GDBP}) p g | |
7412 | $1 = 1 | |
7413 | (@value{GDBP}) set g=4 | |
2df3850c | 7414 | (@value{GDBP}) p g |
c906108c SS |
7415 | $2 = 1 |
7416 | (@value{GDBP}) r | |
7417 | The program being debugged has been started already. | |
7418 | Start it from the beginning? (y or n) y | |
7419 | Starting program: /home/smith/cc_progs/a.out | |
7420 | "/home/smith/cc_progs/a.out": can't open to read symbols: Invalid bfd target. | |
7421 | (@value{GDBP}) show g | |
7422 | The current BFD target is "=4". | |
7423 | @end group | |
7424 | @end example | |
7425 | ||
7426 | @noindent | |
7427 | The program variable @code{g} did not change, and you silently set the | |
7428 | @code{gnutarget} to an invalid value. In order to set the variable | |
7429 | @code{g}, use | |
7430 | ||
7431 | @example | |
7432 | (@value{GDBP}) set var g=4 | |
7433 | @end example | |
c906108c SS |
7434 | |
7435 | @value{GDBN} allows more implicit conversions in assignments than C; you can | |
7436 | freely store an integer value into a pointer variable or vice versa, | |
7437 | and you can convert any structure to any other structure that is the | |
7438 | same length or shorter. | |
7439 | @comment FIXME: how do structs align/pad in these conversions? | |
7440 | @comment /doc@cygnus.com 18dec1990 | |
7441 | ||
7442 | To store values into arbitrary places in memory, use the @samp{@{@dots{}@}} | |
7443 | construct to generate a value of specified type at a specified address | |
7444 | (@pxref{Expressions, ,Expressions}). For example, @code{@{int@}0x83040} refers | |
7445 | to memory location @code{0x83040} as an integer (which implies a certain size | |
7446 | and representation in memory), and | |
7447 | ||
7448 | @example | |
7449 | set @{int@}0x83040 = 4 | |
7450 | @end example | |
7451 | ||
7452 | @noindent | |
7453 | stores the value 4 into that memory location. | |
7454 | ||
53a5351d | 7455 | @node Jumping |
c906108c SS |
7456 | @section Continuing at a different address |
7457 | ||
7458 | Ordinarily, when you continue your program, you do so at the place where | |
7459 | it stopped, with the @code{continue} command. You can instead continue at | |
7460 | an address of your own choosing, with the following commands: | |
7461 | ||
7462 | @table @code | |
7463 | @kindex jump | |
7464 | @item jump @var{linespec} | |
7465 | Resume execution at line @var{linespec}. Execution stops again | |
7466 | immediately if there is a breakpoint there. @xref{List, ,Printing | |
7467 | source lines}, for a description of the different forms of | |
7468 | @var{linespec}. It is common practice to use the @code{tbreak} command | |
7469 | in conjunction with @code{jump}. @xref{Set Breaks, ,Setting | |
7470 | breakpoints}. | |
7471 | ||
7472 | The @code{jump} command does not change the current stack frame, or | |
7473 | the stack pointer, or the contents of any memory location or any | |
7474 | register other than the program counter. If line @var{linespec} is in | |
7475 | a different function from the one currently executing, the results may | |
7476 | be bizarre if the two functions expect different patterns of arguments or | |
7477 | of local variables. For this reason, the @code{jump} command requests | |
7478 | confirmation if the specified line is not in the function currently | |
7479 | executing. However, even bizarre results are predictable if you are | |
7480 | well acquainted with the machine-language code of your program. | |
7481 | ||
7482 | @item jump *@var{address} | |
7483 | Resume execution at the instruction at address @var{address}. | |
7484 | @end table | |
7485 | ||
c906108c | 7486 | @c Doesn't work on HP-UX; have to set $pcoqh and $pcoqt. |
53a5351d JM |
7487 | On many systems, you can get much the same effect as the @code{jump} |
7488 | command by storing a new value into the register @code{$pc}. The | |
7489 | difference is that this does not start your program running; it only | |
7490 | changes the address of where it @emph{will} run when you continue. For | |
7491 | example, | |
c906108c SS |
7492 | |
7493 | @example | |
7494 | set $pc = 0x485 | |
7495 | @end example | |
7496 | ||
7497 | @noindent | |
7498 | makes the next @code{continue} command or stepping command execute at | |
7499 | address @code{0x485}, rather than at the address where your program stopped. | |
7500 | @xref{Continuing and Stepping, ,Continuing and stepping}. | |
c906108c SS |
7501 | |
7502 | The most common occasion to use the @code{jump} command is to back | |
7503 | up---perhaps with more breakpoints set---over a portion of a program | |
7504 | that has already executed, in order to examine its execution in more | |
7505 | detail. | |
7506 | ||
c906108c | 7507 | @c @group |
53a5351d | 7508 | @node Signaling |
c906108c SS |
7509 | @section Giving your program a signal |
7510 | ||
7511 | @table @code | |
7512 | @kindex signal | |
7513 | @item signal @var{signal} | |
7514 | Resume execution where your program stopped, but immediately give it the | |
7515 | signal @var{signal}. @var{signal} can be the name or the number of a | |
7516 | signal. For example, on many systems @code{signal 2} and @code{signal | |
7517 | SIGINT} are both ways of sending an interrupt signal. | |
7518 | ||
7519 | Alternatively, if @var{signal} is zero, continue execution without | |
7520 | giving a signal. This is useful when your program stopped on account of | |
7521 | a signal and would ordinary see the signal when resumed with the | |
7522 | @code{continue} command; @samp{signal 0} causes it to resume without a | |
7523 | signal. | |
7524 | ||
7525 | @code{signal} does not repeat when you press @key{RET} a second time | |
7526 | after executing the command. | |
7527 | @end table | |
7528 | @c @end group | |
7529 | ||
7530 | Invoking the @code{signal} command is not the same as invoking the | |
7531 | @code{kill} utility from the shell. Sending a signal with @code{kill} | |
7532 | causes @value{GDBN} to decide what to do with the signal depending on | |
7533 | the signal handling tables (@pxref{Signals}). The @code{signal} command | |
7534 | passes the signal directly to your program. | |
7535 | ||
c906108c | 7536 | |
53a5351d | 7537 | @node Returning |
c906108c SS |
7538 | @section Returning from a function |
7539 | ||
7540 | @table @code | |
7541 | @cindex returning from a function | |
7542 | @kindex return | |
7543 | @item return | |
7544 | @itemx return @var{expression} | |
7545 | You can cancel execution of a function call with the @code{return} | |
7546 | command. If you give an | |
7547 | @var{expression} argument, its value is used as the function's return | |
7548 | value. | |
7549 | @end table | |
7550 | ||
7551 | When you use @code{return}, @value{GDBN} discards the selected stack frame | |
7552 | (and all frames within it). You can think of this as making the | |
7553 | discarded frame return prematurely. If you wish to specify a value to | |
7554 | be returned, give that value as the argument to @code{return}. | |
7555 | ||
7556 | This pops the selected stack frame (@pxref{Selection, ,Selecting a | |
7557 | frame}), and any other frames inside of it, leaving its caller as the | |
7558 | innermost remaining frame. That frame becomes selected. The | |
7559 | specified value is stored in the registers used for returning values | |
7560 | of functions. | |
7561 | ||
7562 | The @code{return} command does not resume execution; it leaves the | |
7563 | program stopped in the state that would exist if the function had just | |
7564 | returned. In contrast, the @code{finish} command (@pxref{Continuing | |
7565 | and Stepping, ,Continuing and stepping}) resumes execution until the | |
7566 | selected stack frame returns naturally. | |
7567 | ||
53a5351d | 7568 | @node Calling |
c906108c SS |
7569 | @section Calling program functions |
7570 | ||
7571 | @cindex calling functions | |
7572 | @kindex call | |
7573 | @table @code | |
7574 | @item call @var{expr} | |
7575 | Evaluate the expression @var{expr} without displaying @code{void} | |
7576 | returned values. | |
7577 | @end table | |
7578 | ||
7579 | You can use this variant of the @code{print} command if you want to | |
7580 | execute a function from your program, but without cluttering the output | |
7581 | with @code{void} returned values. If the result is not void, it | |
7582 | is printed and saved in the value history. | |
7583 | ||
c906108c SS |
7584 | For the A29K, a user-controlled variable @code{call_scratch_address}, |
7585 | specifies the location of a scratch area to be used when @value{GDBN} | |
7586 | calls a function in the target. This is necessary because the usual | |
7587 | method of putting the scratch area on the stack does not work in systems | |
7588 | that have separate instruction and data spaces. | |
c906108c | 7589 | |
53a5351d | 7590 | @node Patching |
c906108c | 7591 | @section Patching programs |
7a292a7a | 7592 | |
c906108c SS |
7593 | @cindex patching binaries |
7594 | @cindex writing into executables | |
c906108c | 7595 | @cindex writing into corefiles |
c906108c | 7596 | |
7a292a7a SS |
7597 | By default, @value{GDBN} opens the file containing your program's |
7598 | executable code (or the corefile) read-only. This prevents accidental | |
7599 | alterations to machine code; but it also prevents you from intentionally | |
7600 | patching your program's binary. | |
c906108c SS |
7601 | |
7602 | If you'd like to be able to patch the binary, you can specify that | |
7603 | explicitly with the @code{set write} command. For example, you might | |
7604 | want to turn on internal debugging flags, or even to make emergency | |
7605 | repairs. | |
7606 | ||
7607 | @table @code | |
7608 | @kindex set write | |
7609 | @item set write on | |
7610 | @itemx set write off | |
7a292a7a SS |
7611 | If you specify @samp{set write on}, @value{GDBN} opens executable and |
7612 | core files for both reading and writing; if you specify @samp{set write | |
c906108c SS |
7613 | off} (the default), @value{GDBN} opens them read-only. |
7614 | ||
7615 | If you have already loaded a file, you must load it again (using the | |
7a292a7a SS |
7616 | @code{exec-file} or @code{core-file} command) after changing @code{set |
7617 | write}, for your new setting to take effect. | |
c906108c SS |
7618 | |
7619 | @item show write | |
7620 | @kindex show write | |
7a292a7a SS |
7621 | Display whether executable files and core files are opened for writing |
7622 | as well as reading. | |
c906108c SS |
7623 | @end table |
7624 | ||
53a5351d | 7625 | @node GDB Files |
c906108c SS |
7626 | @chapter @value{GDBN} Files |
7627 | ||
7a292a7a SS |
7628 | @value{GDBN} needs to know the file name of the program to be debugged, |
7629 | both in order to read its symbol table and in order to start your | |
7630 | program. To debug a core dump of a previous run, you must also tell | |
7631 | @value{GDBN} the name of the core dump file. | |
c906108c SS |
7632 | |
7633 | @menu | |
7634 | * Files:: Commands to specify files | |
7635 | * Symbol Errors:: Errors reading symbol files | |
7636 | @end menu | |
7637 | ||
53a5351d | 7638 | @node Files |
c906108c | 7639 | @section Commands to specify files |
c906108c | 7640 | |
7a292a7a | 7641 | @cindex symbol table |
c906108c | 7642 | @cindex core dump file |
7a292a7a SS |
7643 | |
7644 | You may want to specify executable and core dump file names. The usual | |
7645 | way to do this is at start-up time, using the arguments to | |
7646 | @value{GDBN}'s start-up commands (@pxref{Invocation, , Getting In and | |
7647 | Out of @value{GDBN}}). | |
c906108c SS |
7648 | |
7649 | Occasionally it is necessary to change to a different file during a | |
7650 | @value{GDBN} session. Or you may run @value{GDBN} and forget to specify | |
7651 | a file you want to use. In these situations the @value{GDBN} commands | |
7652 | to specify new files are useful. | |
7653 | ||
7654 | @table @code | |
7655 | @cindex executable file | |
7656 | @kindex file | |
7657 | @item file @var{filename} | |
7658 | Use @var{filename} as the program to be debugged. It is read for its | |
7659 | symbols and for the contents of pure memory. It is also the program | |
7660 | executed when you use the @code{run} command. If you do not specify a | |
7661 | directory and the file is not found in the @value{GDBN} working directory, | |
7662 | @value{GDBN} uses the environment variable @code{PATH} as a list of | |
7663 | directories to search, just as the shell does when looking for a program | |
7664 | to run. You can change the value of this variable, for both @value{GDBN} | |
7665 | and your program, using the @code{path} command. | |
7666 | ||
c906108c SS |
7667 | On systems with memory-mapped files, an auxiliary file |
7668 | @file{@var{filename}.syms} may hold symbol table information for | |
7669 | @var{filename}. If so, @value{GDBN} maps in the symbol table from | |
7670 | @file{@var{filename}.syms}, starting up more quickly. See the | |
7671 | descriptions of the file options @samp{-mapped} and @samp{-readnow} | |
7672 | (available on the command line, and with the commands @code{file}, | |
7673 | @code{symbol-file}, or @code{add-symbol-file}, described below), | |
7674 | for more information. | |
c906108c SS |
7675 | |
7676 | @item file | |
7677 | @code{file} with no argument makes @value{GDBN} discard any information it | |
7678 | has on both executable file and the symbol table. | |
7679 | ||
7680 | @kindex exec-file | |
7681 | @item exec-file @r{[} @var{filename} @r{]} | |
7682 | Specify that the program to be run (but not the symbol table) is found | |
7683 | in @var{filename}. @value{GDBN} searches the environment variable @code{PATH} | |
7684 | if necessary to locate your program. Omitting @var{filename} means to | |
7685 | discard information on the executable file. | |
7686 | ||
7687 | @kindex symbol-file | |
7688 | @item symbol-file @r{[} @var{filename} @r{]} | |
7689 | Read symbol table information from file @var{filename}. @code{PATH} is | |
7690 | searched when necessary. Use the @code{file} command to get both symbol | |
7691 | table and program to run from the same file. | |
7692 | ||
7693 | @code{symbol-file} with no argument clears out @value{GDBN} information on your | |
7694 | program's symbol table. | |
7695 | ||
7696 | The @code{symbol-file} command causes @value{GDBN} to forget the contents | |
7697 | of its convenience variables, the value history, and all breakpoints and | |
7698 | auto-display expressions. This is because they may contain pointers to | |
7699 | the internal data recording symbols and data types, which are part of | |
7700 | the old symbol table data being discarded inside @value{GDBN}. | |
7701 | ||
7702 | @code{symbol-file} does not repeat if you press @key{RET} again after | |
7703 | executing it once. | |
7704 | ||
7705 | When @value{GDBN} is configured for a particular environment, it | |
7706 | understands debugging information in whatever format is the standard | |
7707 | generated for that environment; you may use either a @sc{gnu} compiler, or | |
7708 | other compilers that adhere to the local conventions. | |
c906108c SS |
7709 | Best results are usually obtained from @sc{gnu} compilers; for example, |
7710 | using @code{@value{GCC}} you can generate debugging information for | |
7711 | optimized code. | |
c906108c SS |
7712 | |
7713 | For most kinds of object files, with the exception of old SVR3 systems | |
7714 | using COFF, the @code{symbol-file} command does not normally read the | |
7715 | symbol table in full right away. Instead, it scans the symbol table | |
7716 | quickly to find which source files and which symbols are present. The | |
7717 | details are read later, one source file at a time, as they are needed. | |
7718 | ||
7719 | The purpose of this two-stage reading strategy is to make @value{GDBN} | |
7720 | start up faster. For the most part, it is invisible except for | |
7721 | occasional pauses while the symbol table details for a particular source | |
7722 | file are being read. (The @code{set verbose} command can turn these | |
7723 | pauses into messages if desired. @xref{Messages/Warnings, ,Optional | |
7724 | warnings and messages}.) | |
7725 | ||
c906108c SS |
7726 | We have not implemented the two-stage strategy for COFF yet. When the |
7727 | symbol table is stored in COFF format, @code{symbol-file} reads the | |
7728 | symbol table data in full right away. Note that ``stabs-in-COFF'' | |
7729 | still does the two-stage strategy, since the debug info is actually | |
7730 | in stabs format. | |
7731 | ||
7732 | @kindex readnow | |
7733 | @cindex reading symbols immediately | |
7734 | @cindex symbols, reading immediately | |
7735 | @kindex mapped | |
7736 | @cindex memory-mapped symbol file | |
7737 | @cindex saving symbol table | |
7738 | @item symbol-file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]} | |
7739 | @itemx file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]} | |
7740 | You can override the @value{GDBN} two-stage strategy for reading symbol | |
7741 | tables by using the @samp{-readnow} option with any of the commands that | |
7742 | load symbol table information, if you want to be sure @value{GDBN} has the | |
7743 | entire symbol table available. | |
c906108c | 7744 | |
c906108c SS |
7745 | If memory-mapped files are available on your system through the |
7746 | @code{mmap} system call, you can use another option, @samp{-mapped}, to | |
7747 | cause @value{GDBN} to write the symbols for your program into a reusable | |
7748 | file. Future @value{GDBN} debugging sessions map in symbol information | |
7749 | from this auxiliary symbol file (if the program has not changed), rather | |
7750 | than spending time reading the symbol table from the executable | |
7751 | program. Using the @samp{-mapped} option has the same effect as | |
7752 | starting @value{GDBN} with the @samp{-mapped} command-line option. | |
7753 | ||
7754 | You can use both options together, to make sure the auxiliary symbol | |
7755 | file has all the symbol information for your program. | |
7756 | ||
7757 | The auxiliary symbol file for a program called @var{myprog} is called | |
7758 | @samp{@var{myprog}.syms}. Once this file exists (so long as it is newer | |
7759 | than the corresponding executable), @value{GDBN} always attempts to use | |
7760 | it when you debug @var{myprog}; no special options or commands are | |
7761 | needed. | |
7762 | ||
7763 | The @file{.syms} file is specific to the host machine where you run | |
7764 | @value{GDBN}. It holds an exact image of the internal @value{GDBN} | |
7765 | symbol table. It cannot be shared across multiple host platforms. | |
c906108c SS |
7766 | |
7767 | @c FIXME: for now no mention of directories, since this seems to be in | |
7768 | @c flux. 13mar1992 status is that in theory GDB would look either in | |
7769 | @c current dir or in same dir as myprog; but issues like competing | |
7770 | @c GDB's, or clutter in system dirs, mean that in practice right now | |
7771 | @c only current dir is used. FFish says maybe a special GDB hierarchy | |
7772 | @c (eg rooted in val of env var GDBSYMS) could exist for mappable symbol | |
7773 | @c files. | |
7774 | ||
7775 | @kindex core | |
7776 | @kindex core-file | |
7777 | @item core-file @r{[} @var{filename} @r{]} | |
7778 | Specify the whereabouts of a core dump file to be used as the ``contents | |
7779 | of memory''. Traditionally, core files contain only some parts of the | |
7780 | address space of the process that generated them; @value{GDBN} can access the | |
7781 | executable file itself for other parts. | |
7782 | ||
7783 | @code{core-file} with no argument specifies that no core file is | |
7784 | to be used. | |
7785 | ||
7786 | Note that the core file is ignored when your program is actually running | |
7a292a7a SS |
7787 | under @value{GDBN}. So, if you have been running your program and you |
7788 | wish to debug a core file instead, you must kill the subprocess in which | |
7789 | the program is running. To do this, use the @code{kill} command | |
c906108c | 7790 | (@pxref{Kill Process, ,Killing the child process}). |
c906108c | 7791 | |
c906108c SS |
7792 | @kindex add-symbol-file |
7793 | @cindex dynamic linking | |
7794 | @item add-symbol-file @var{filename} @var{address} | |
7795 | @itemx add-symbol-file @var{filename} @var{address} @r{[} -readnow @r{]} @r{[} -mapped @r{]} | |
2acceee2 JM |
7796 | @itemx add-symbol-file @var{filename} @var{address} @var{data_address} @var{bss_address} |
7797 | @itemx add-symbol-file @var{filename} @r{-T}@var{section} @var{address} | |
c906108c SS |
7798 | The @code{add-symbol-file} command reads additional symbol table information |
7799 | from the file @var{filename}. You would use this command when @var{filename} | |
7800 | has been dynamically loaded (by some other means) into the program that | |
7801 | is running. @var{address} should be the memory address at which the | |
7802 | file has been loaded; @value{GDBN} cannot figure this out for itself. | |
2acceee2 JM |
7803 | You can specify up to three addresses, in which case they are taken to be |
7804 | the addresses of the text, data, and bss segments respectively. | |
7805 | For complicated cases, you can specify an arbitrary number of @r{-T}@var{section} @var{address} | |
7806 | pairs, to give an explicit section name and base address for that section. | |
7807 | You can specify any @var{address} as an expression. | |
c906108c SS |
7808 | |
7809 | The symbol table of the file @var{filename} is added to the symbol table | |
7810 | originally read with the @code{symbol-file} command. You can use the | |
7811 | @code{add-symbol-file} command any number of times; the new symbol data thus | |
7812 | read keeps adding to the old. To discard all old symbol data instead, | |
7813 | use the @code{symbol-file} command. | |
7814 | ||
7815 | @code{add-symbol-file} does not repeat if you press @key{RET} after using it. | |
7816 | ||
7817 | You can use the @samp{-mapped} and @samp{-readnow} options just as with | |
7818 | the @code{symbol-file} command, to change how @value{GDBN} manages the symbol | |
7819 | table information for @var{filename}. | |
7820 | ||
7821 | @kindex add-shared-symbol-file | |
7822 | @item add-shared-symbol-file | |
7823 | The @code{add-shared-symbol-file} command can be used only under Harris' CXUX | |
7824 | operating system for the Motorola 88k. @value{GDBN} automatically looks for | |
7825 | shared libraries, however if @value{GDBN} does not find yours, you can run | |
7826 | @code{add-shared-symbol-file}. It takes no arguments. | |
c906108c | 7827 | |
c906108c SS |
7828 | @kindex section |
7829 | @item section | |
7830 | The @code{section} command changes the base address of section SECTION of | |
7831 | the exec file to ADDR. This can be used if the exec file does not contain | |
7832 | section addresses, (such as in the a.out format), or when the addresses | |
7833 | specified in the file itself are wrong. Each section must be changed | |
d4f3574e SS |
7834 | separately. The @code{info files} command, described below, lists all |
7835 | the sections and their addresses. | |
c906108c SS |
7836 | |
7837 | @kindex info files | |
7838 | @kindex info target | |
7839 | @item info files | |
7840 | @itemx info target | |
7a292a7a SS |
7841 | @code{info files} and @code{info target} are synonymous; both print the |
7842 | current target (@pxref{Targets, ,Specifying a Debugging Target}), | |
7843 | including the names of the executable and core dump files currently in | |
7844 | use by @value{GDBN}, and the files from which symbols were loaded. The | |
7845 | command @code{help target} lists all possible targets rather than | |
7846 | current ones. | |
7847 | ||
c906108c SS |
7848 | @end table |
7849 | ||
7850 | All file-specifying commands allow both absolute and relative file names | |
7851 | as arguments. @value{GDBN} always converts the file name to an absolute file | |
7852 | name and remembers it that way. | |
7853 | ||
c906108c | 7854 | @cindex shared libraries |
c906108c SS |
7855 | @value{GDBN} supports HP-UX, SunOS, SVr4, Irix 5, and IBM RS/6000 shared |
7856 | libraries. | |
53a5351d | 7857 | |
c906108c SS |
7858 | @value{GDBN} automatically loads symbol definitions from shared libraries |
7859 | when you use the @code{run} command, or when you examine a core file. | |
7860 | (Before you issue the @code{run} command, @value{GDBN} does not understand | |
7861 | references to a function in a shared library, however---unless you are | |
7862 | debugging a core file). | |
53a5351d JM |
7863 | |
7864 | On HP-UX, if the program loads a library explicitly, @value{GDBN} | |
7865 | automatically loads the symbols at the time of the @code{shl_load} call. | |
7866 | ||
c906108c SS |
7867 | @c FIXME: some @value{GDBN} release may permit some refs to undef |
7868 | @c FIXME...symbols---eg in a break cmd---assuming they are from a shared | |
7869 | @c FIXME...lib; check this from time to time when updating manual | |
7870 | ||
7871 | @table @code | |
7872 | @kindex info sharedlibrary | |
7873 | @kindex info share | |
7874 | @item info share | |
7875 | @itemx info sharedlibrary | |
7876 | Print the names of the shared libraries which are currently loaded. | |
7877 | ||
7878 | @kindex sharedlibrary | |
7879 | @kindex share | |
7880 | @item sharedlibrary @var{regex} | |
7881 | @itemx share @var{regex} | |
c906108c SS |
7882 | Load shared object library symbols for files matching a |
7883 | Unix regular expression. | |
7884 | As with files loaded automatically, it only loads shared libraries | |
7885 | required by your program for a core file or after typing @code{run}. If | |
7886 | @var{regex} is omitted all shared libraries required by your program are | |
7887 | loaded. | |
7888 | @end table | |
7889 | ||
53a5351d JM |
7890 | On HP-UX systems, @value{GDBN} detects the loading of a shared library |
7891 | and automatically reads in symbols from the newly loaded library, up to | |
7892 | a threshold that is initially set but that you can modify if you wish. | |
c906108c SS |
7893 | |
7894 | Beyond that threshold, symbols from shared libraries must be explicitly | |
d4f3574e SS |
7895 | loaded. To load these symbols, use the command @code{sharedlibrary |
7896 | @var{filename}}. The base address of the shared library is determined | |
c906108c SS |
7897 | automatically by @value{GDBN} and need not be specified. |
7898 | ||
7899 | To display or set the threshold, use the commands: | |
7900 | ||
7901 | @table @code | |
7902 | @kindex set auto-solib-add | |
7903 | @item set auto-solib-add @var{threshold} | |
7904 | Set the autoloading size threshold, in megabytes. If @var{threshold} is | |
7905 | nonzero, symbols from all shared object libraries will be loaded | |
7906 | automatically when the inferior begins execution or when the dynamic | |
7907 | linker informs @value{GDBN} that a new library has been loaded, until | |
7908 | the symbol table of the program and libraries exceeds this threshold. | |
7909 | Otherwise, symbols must be loaded manually, using the | |
7910 | @code{sharedlibrary} command. The default threshold is 100 megabytes. | |
7911 | ||
7912 | @kindex show auto-solib-add | |
7913 | @item show auto-solib-add | |
7914 | Display the current autoloading size threshold, in megabytes. | |
7915 | @end table | |
c906108c | 7916 | |
53a5351d | 7917 | @node Symbol Errors |
c906108c SS |
7918 | @section Errors reading symbol files |
7919 | ||
7920 | While reading a symbol file, @value{GDBN} occasionally encounters problems, | |
7921 | such as symbol types it does not recognize, or known bugs in compiler | |
7922 | output. By default, @value{GDBN} does not notify you of such problems, since | |
7923 | they are relatively common and primarily of interest to people | |
7924 | debugging compilers. If you are interested in seeing information | |
7925 | about ill-constructed symbol tables, you can either ask @value{GDBN} to print | |
7926 | only one message about each such type of problem, no matter how many | |
7927 | times the problem occurs; or you can ask @value{GDBN} to print more messages, | |
7928 | to see how many times the problems occur, with the @code{set | |
7929 | complaints} command (@pxref{Messages/Warnings, ,Optional warnings and | |
7930 | messages}). | |
7931 | ||
7932 | The messages currently printed, and their meanings, include: | |
7933 | ||
7934 | @table @code | |
7935 | @item inner block not inside outer block in @var{symbol} | |
7936 | ||
7937 | The symbol information shows where symbol scopes begin and end | |
7938 | (such as at the start of a function or a block of statements). This | |
7939 | error indicates that an inner scope block is not fully contained | |
7940 | in its outer scope blocks. | |
7941 | ||
7942 | @value{GDBN} circumvents the problem by treating the inner block as if it had | |
7943 | the same scope as the outer block. In the error message, @var{symbol} | |
7944 | may be shown as ``@code{(don't know)}'' if the outer block is not a | |
7945 | function. | |
7946 | ||
7947 | @item block at @var{address} out of order | |
7948 | ||
7949 | The symbol information for symbol scope blocks should occur in | |
7950 | order of increasing addresses. This error indicates that it does not | |
7951 | do so. | |
7952 | ||
7953 | @value{GDBN} does not circumvent this problem, and has trouble | |
7954 | locating symbols in the source file whose symbols it is reading. (You | |
7955 | can often determine what source file is affected by specifying | |
7956 | @code{set verbose on}. @xref{Messages/Warnings, ,Optional warnings and | |
7957 | messages}.) | |
7958 | ||
7959 | @item bad block start address patched | |
7960 | ||
7961 | The symbol information for a symbol scope block has a start address | |
7962 | smaller than the address of the preceding source line. This is known | |
7963 | to occur in the SunOS 4.1.1 (and earlier) C compiler. | |
7964 | ||
7965 | @value{GDBN} circumvents the problem by treating the symbol scope block as | |
7966 | starting on the previous source line. | |
7967 | ||
7968 | @item bad string table offset in symbol @var{n} | |
7969 | ||
7970 | @cindex foo | |
7971 | Symbol number @var{n} contains a pointer into the string table which is | |
7972 | larger than the size of the string table. | |
7973 | ||
7974 | @value{GDBN} circumvents the problem by considering the symbol to have the | |
7975 | name @code{foo}, which may cause other problems if many symbols end up | |
7976 | with this name. | |
7977 | ||
7978 | @item unknown symbol type @code{0x@var{nn}} | |
7979 | ||
7a292a7a SS |
7980 | The symbol information contains new data types that @value{GDBN} does |
7981 | not yet know how to read. @code{0x@var{nn}} is the symbol type of the | |
d4f3574e | 7982 | uncomprehended information, in hexadecimal. |
c906108c | 7983 | |
7a292a7a SS |
7984 | @value{GDBN} circumvents the error by ignoring this symbol information. |
7985 | This usually allows you to debug your program, though certain symbols | |
c906108c | 7986 | are not accessible. If you encounter such a problem and feel like |
7a292a7a SS |
7987 | debugging it, you can debug @code{@value{GDBP}} with itself, breakpoint |
7988 | on @code{complain}, then go up to the function @code{read_dbx_symtab} | |
7989 | and examine @code{*bufp} to see the symbol. | |
c906108c SS |
7990 | |
7991 | @item stub type has NULL name | |
c906108c | 7992 | |
7a292a7a | 7993 | @value{GDBN} could not find the full definition for a struct or class. |
c906108c | 7994 | |
7a292a7a | 7995 | @item const/volatile indicator missing (ok if using g++ v1.x), got@dots{} |
c906108c | 7996 | The symbol information for a C++ member function is missing some |
7a292a7a SS |
7997 | information that recent versions of the compiler should have output for |
7998 | it. | |
c906108c SS |
7999 | |
8000 | @item info mismatch between compiler and debugger | |
8001 | ||
8002 | @value{GDBN} could not parse a type specification output by the compiler. | |
7a292a7a | 8003 | |
c906108c SS |
8004 | @end table |
8005 | ||
53a5351d | 8006 | @node Targets |
c906108c | 8007 | @chapter Specifying a Debugging Target |
7a292a7a | 8008 | |
c906108c SS |
8009 | @cindex debugging target |
8010 | @kindex target | |
8011 | ||
8012 | A @dfn{target} is the execution environment occupied by your program. | |
53a5351d JM |
8013 | |
8014 | Often, @value{GDBN} runs in the same host environment as your program; | |
8015 | in that case, the debugging target is specified as a side effect when | |
8016 | you use the @code{file} or @code{core} commands. When you need more | |
c906108c SS |
8017 | flexibility---for example, running @value{GDBN} on a physically separate |
8018 | host, or controlling a standalone system over a serial port or a | |
53a5351d JM |
8019 | realtime system over a TCP/IP connection---you can use the @code{target} |
8020 | command to specify one of the target types configured for @value{GDBN} | |
8021 | (@pxref{Target Commands, ,Commands for managing targets}). | |
c906108c SS |
8022 | |
8023 | @menu | |
8024 | * Active Targets:: Active targets | |
8025 | * Target Commands:: Commands for managing targets | |
c906108c SS |
8026 | * Byte Order:: Choosing target byte order |
8027 | * Remote:: Remote debugging | |
96baa820 | 8028 | * KOD:: Kernel Object Display |
c906108c SS |
8029 | |
8030 | @end menu | |
8031 | ||
53a5351d | 8032 | @node Active Targets |
c906108c | 8033 | @section Active targets |
7a292a7a | 8034 | |
c906108c SS |
8035 | @cindex stacking targets |
8036 | @cindex active targets | |
8037 | @cindex multiple targets | |
8038 | ||
c906108c | 8039 | There are three classes of targets: processes, core files, and |
7a292a7a SS |
8040 | executable files. @value{GDBN} can work concurrently on up to three |
8041 | active targets, one in each class. This allows you to (for example) | |
8042 | start a process and inspect its activity without abandoning your work on | |
8043 | a core file. | |
c906108c SS |
8044 | |
8045 | For example, if you execute @samp{gdb a.out}, then the executable file | |
8046 | @code{a.out} is the only active target. If you designate a core file as | |
8047 | well---presumably from a prior run that crashed and coredumped---then | |
8048 | @value{GDBN} has two active targets and uses them in tandem, looking | |
8049 | first in the corefile target, then in the executable file, to satisfy | |
8050 | requests for memory addresses. (Typically, these two classes of target | |
8051 | are complementary, since core files contain only a program's | |
8052 | read-write memory---variables and so on---plus machine status, while | |
8053 | executable files contain only the program text and initialized data.) | |
c906108c SS |
8054 | |
8055 | When you type @code{run}, your executable file becomes an active process | |
7a292a7a SS |
8056 | target as well. When a process target is active, all @value{GDBN} |
8057 | commands requesting memory addresses refer to that target; addresses in | |
8058 | an active core file or executable file target are obscured while the | |
8059 | process target is active. | |
c906108c | 8060 | |
7a292a7a SS |
8061 | Use the @code{core-file} and @code{exec-file} commands to select a new |
8062 | core file or executable target (@pxref{Files, ,Commands to specify | |
c906108c | 8063 | files}). To specify as a target a process that is already running, use |
7a292a7a SS |
8064 | the @code{attach} command (@pxref{Attach, ,Debugging an already-running |
8065 | process}). | |
c906108c | 8066 | |
53a5351d | 8067 | @node Target Commands |
c906108c SS |
8068 | @section Commands for managing targets |
8069 | ||
8070 | @table @code | |
8071 | @item target @var{type} @var{parameters} | |
7a292a7a SS |
8072 | Connects the @value{GDBN} host environment to a target machine or |
8073 | process. A target is typically a protocol for talking to debugging | |
8074 | facilities. You use the argument @var{type} to specify the type or | |
8075 | protocol of the target machine. | |
c906108c SS |
8076 | |
8077 | Further @var{parameters} are interpreted by the target protocol, but | |
8078 | typically include things like device names or host names to connect | |
8079 | with, process numbers, and baud rates. | |
c906108c SS |
8080 | |
8081 | The @code{target} command does not repeat if you press @key{RET} again | |
8082 | after executing the command. | |
8083 | ||
8084 | @kindex help target | |
8085 | @item help target | |
8086 | Displays the names of all targets available. To display targets | |
8087 | currently selected, use either @code{info target} or @code{info files} | |
8088 | (@pxref{Files, ,Commands to specify files}). | |
8089 | ||
8090 | @item help target @var{name} | |
8091 | Describe a particular target, including any parameters necessary to | |
8092 | select it. | |
8093 | ||
8094 | @kindex set gnutarget | |
8095 | @item set gnutarget @var{args} | |
8096 | @value{GDBN} uses its own library BFD to read your files. @value{GDBN} | |
8097 | knows whether it is reading an @dfn{executable}, | |
8098 | a @dfn{core}, or a @dfn{.o} file; however, you can specify the file format | |
8099 | with the @code{set gnutarget} command. Unlike most @code{target} commands, | |
8100 | with @code{gnutarget} the @code{target} refers to a program, not a machine. | |
8101 | ||
d4f3574e | 8102 | @quotation |
c906108c SS |
8103 | @emph{Warning:} To specify a file format with @code{set gnutarget}, |
8104 | you must know the actual BFD name. | |
d4f3574e | 8105 | @end quotation |
c906108c | 8106 | |
d4f3574e SS |
8107 | @noindent |
8108 | @xref{Files, , Commands to specify files}. | |
c906108c SS |
8109 | |
8110 | @kindex show gnutarget | |
8111 | @item show gnutarget | |
8112 | Use the @code{show gnutarget} command to display what file format | |
8113 | @code{gnutarget} is set to read. If you have not set @code{gnutarget}, | |
8114 | @value{GDBN} will determine the file format for each file automatically, | |
8115 | and @code{show gnutarget} displays @samp{The current BDF target is "auto"}. | |
8116 | @end table | |
8117 | ||
c906108c SS |
8118 | Here are some common targets (available, or not, depending on the GDB |
8119 | configuration): | |
c906108c SS |
8120 | |
8121 | @table @code | |
8122 | @kindex target exec | |
8123 | @item target exec @var{program} | |
8124 | An executable file. @samp{target exec @var{program}} is the same as | |
8125 | @samp{exec-file @var{program}}. | |
8126 | ||
c906108c SS |
8127 | @kindex target core |
8128 | @item target core @var{filename} | |
8129 | A core dump file. @samp{target core @var{filename}} is the same as | |
8130 | @samp{core-file @var{filename}}. | |
c906108c SS |
8131 | |
8132 | @kindex target remote | |
8133 | @item target remote @var{dev} | |
8134 | Remote serial target in GDB-specific protocol. The argument @var{dev} | |
8135 | specifies what serial device to use for the connection (e.g. | |
8136 | @file{/dev/ttya}). @xref{Remote, ,Remote debugging}. @code{target remote} | |
d4f3574e | 8137 | supports the @code{load} command. This is only useful if you have |
c906108c SS |
8138 | some other way of getting the stub to the target system, and you can put |
8139 | it somewhere in memory where it won't get clobbered by the download. | |
8140 | ||
c906108c SS |
8141 | @kindex target sim |
8142 | @item target sim | |
2df3850c | 8143 | Builtin CPU simulator. @value{GDBN} includes simulators for most architectures. |
104c1213 JM |
8144 | In general, |
8145 | @example | |
8146 | target sim | |
8147 | load | |
8148 | run | |
8149 | @end example | |
d4f3574e | 8150 | @noindent |
104c1213 | 8151 | works; however, you cannot assume that a specific memory map, device |
d4f3574e | 8152 | drivers, or even basic I/O is available, although some simulators do |
104c1213 JM |
8153 | provide these. For info about any processor-specific simulator details, |
8154 | see the appropriate section in @ref{Embedded Processors, ,Embedded | |
8155 | Processors}. | |
8156 | ||
c906108c SS |
8157 | @end table |
8158 | ||
104c1213 | 8159 | Some configurations may include these targets as well: |
c906108c SS |
8160 | |
8161 | @table @code | |
8162 | ||
c906108c SS |
8163 | @kindex target nrom |
8164 | @item target nrom @var{dev} | |
8165 | NetROM ROM emulator. This target only supports downloading. | |
8166 | ||
c906108c SS |
8167 | @end table |
8168 | ||
c906108c SS |
8169 | Different targets are available on different configurations of @value{GDBN}; |
8170 | your configuration may have more or fewer targets. | |
c906108c SS |
8171 | |
8172 | Many remote targets require you to download the executable's code | |
8173 | once you've successfully established a connection. | |
8174 | ||
8175 | @table @code | |
8176 | ||
8177 | @kindex load @var{filename} | |
8178 | @item load @var{filename} | |
c906108c SS |
8179 | Depending on what remote debugging facilities are configured into |
8180 | @value{GDBN}, the @code{load} command may be available. Where it exists, it | |
8181 | is meant to make @var{filename} (an executable) available for debugging | |
8182 | on the remote system---by downloading, or dynamic linking, for example. | |
8183 | @code{load} also records the @var{filename} symbol table in @value{GDBN}, like | |
8184 | the @code{add-symbol-file} command. | |
8185 | ||
8186 | If your @value{GDBN} does not have a @code{load} command, attempting to | |
8187 | execute it gets the error message ``@code{You can't do that when your | |
8188 | target is @dots{}}'' | |
c906108c SS |
8189 | |
8190 | The file is loaded at whatever address is specified in the executable. | |
8191 | For some object file formats, you can specify the load address when you | |
8192 | link the program; for other formats, like a.out, the object file format | |
8193 | specifies a fixed address. | |
8194 | @c FIXME! This would be a good place for an xref to the GNU linker doc. | |
8195 | ||
c906108c SS |
8196 | @code{load} does not repeat if you press @key{RET} again after using it. |
8197 | @end table | |
8198 | ||
53a5351d | 8199 | @node Byte Order |
c906108c | 8200 | @section Choosing target byte order |
7a292a7a | 8201 | |
c906108c SS |
8202 | @cindex choosing target byte order |
8203 | @cindex target byte order | |
8204 | @kindex set endian big | |
8205 | @kindex set endian little | |
8206 | @kindex set endian auto | |
8207 | @kindex show endian | |
8208 | ||
8209 | Some types of processors, such as the MIPS, PowerPC, and Hitachi SH, | |
8210 | offer the ability to run either big-endian or little-endian byte | |
8211 | orders. Usually the executable or symbol will include a bit to | |
8212 | designate the endian-ness, and you will not need to worry about | |
8213 | which to use. However, you may still find it useful to adjust | |
d4f3574e | 8214 | @value{GDBN}'s idea of processor endian-ness manually. |
c906108c SS |
8215 | |
8216 | @table @code | |
8217 | @kindex set endian big | |
8218 | @item set endian big | |
8219 | Instruct @value{GDBN} to assume the target is big-endian. | |
8220 | ||
8221 | @kindex set endian little | |
8222 | @item set endian little | |
8223 | Instruct @value{GDBN} to assume the target is little-endian. | |
8224 | ||
8225 | @kindex set endian auto | |
8226 | @item set endian auto | |
8227 | Instruct @value{GDBN} to use the byte order associated with the | |
8228 | executable. | |
8229 | ||
8230 | @item show endian | |
8231 | Display @value{GDBN}'s current idea of the target byte order. | |
8232 | ||
8233 | @end table | |
8234 | ||
8235 | Note that these commands merely adjust interpretation of symbolic | |
8236 | data on the host, and that they have absolutely no effect on the | |
8237 | target system. | |
8238 | ||
53a5351d | 8239 | @node Remote |
c906108c SS |
8240 | @section Remote debugging |
8241 | @cindex remote debugging | |
8242 | ||
8243 | If you are trying to debug a program running on a machine that cannot run | |
8244 | @value{GDBN} in the usual way, it is often useful to use remote debugging. | |
8245 | For example, you might use remote debugging on an operating system kernel, | |
8246 | or on a small system which does not have a general purpose operating system | |
8247 | powerful enough to run a full-featured debugger. | |
8248 | ||
8249 | Some configurations of @value{GDBN} have special serial or TCP/IP interfaces | |
8250 | to make this work with particular debugging targets. In addition, | |
8251 | @value{GDBN} comes with a generic serial protocol (specific to @value{GDBN}, | |
8252 | but not specific to any particular target system) which you can use if you | |
8253 | write the remote stubs---the code that runs on the remote system to | |
8254 | communicate with @value{GDBN}. | |
8255 | ||
8256 | Other remote targets may be available in your | |
8257 | configuration of @value{GDBN}; use @code{help target} to list them. | |
c906108c | 8258 | |
c906108c | 8259 | @menu |
c906108c | 8260 | * Remote Serial:: @value{GDBN} remote serial protocol |
c906108c SS |
8261 | @end menu |
8262 | ||
104c1213 JM |
8263 | @node Remote Serial |
8264 | @subsection The @value{GDBN} remote serial protocol | |
7a292a7a | 8265 | |
104c1213 JM |
8266 | @cindex remote serial debugging, overview |
8267 | To debug a program running on another machine (the debugging | |
8268 | @dfn{target} machine), you must first arrange for all the usual | |
8269 | prerequisites for the program to run by itself. For example, for a C | |
8270 | program, you need: | |
c906108c | 8271 | |
104c1213 JM |
8272 | @enumerate |
8273 | @item | |
8274 | A startup routine to set up the C runtime environment; these usually | |
8275 | have a name like @file{crt0}. The startup routine may be supplied by | |
8276 | your hardware supplier, or you may have to write your own. | |
96baa820 | 8277 | |
104c1213 | 8278 | @item |
d4f3574e | 8279 | A C subroutine library to support your program's |
104c1213 | 8280 | subroutine calls, notably managing input and output. |
96baa820 | 8281 | |
104c1213 JM |
8282 | @item |
8283 | A way of getting your program to the other machine---for example, a | |
8284 | download program. These are often supplied by the hardware | |
8285 | manufacturer, but you may have to write your own from hardware | |
8286 | documentation. | |
8287 | @end enumerate | |
96baa820 | 8288 | |
104c1213 JM |
8289 | The next step is to arrange for your program to use a serial port to |
8290 | communicate with the machine where @value{GDBN} is running (the @dfn{host} | |
8291 | machine). In general terms, the scheme looks like this: | |
96baa820 | 8292 | |
104c1213 JM |
8293 | @table @emph |
8294 | @item On the host, | |
8295 | @value{GDBN} already understands how to use this protocol; when everything | |
8296 | else is set up, you can simply use the @samp{target remote} command | |
8297 | (@pxref{Targets,,Specifying a Debugging Target}). | |
8298 | ||
8299 | @item On the target, | |
8300 | you must link with your program a few special-purpose subroutines that | |
8301 | implement the @value{GDBN} remote serial protocol. The file containing these | |
8302 | subroutines is called a @dfn{debugging stub}. | |
8303 | ||
8304 | On certain remote targets, you can use an auxiliary program | |
8305 | @code{gdbserver} instead of linking a stub into your program. | |
8306 | @xref{Server,,Using the @code{gdbserver} program}, for details. | |
8307 | @end table | |
96baa820 | 8308 | |
104c1213 JM |
8309 | The debugging stub is specific to the architecture of the remote |
8310 | machine; for example, use @file{sparc-stub.c} to debug programs on | |
8311 | @sc{sparc} boards. | |
96baa820 | 8312 | |
104c1213 JM |
8313 | @cindex remote serial stub list |
8314 | These working remote stubs are distributed with @value{GDBN}: | |
96baa820 | 8315 | |
104c1213 JM |
8316 | @table @code |
8317 | ||
8318 | @item i386-stub.c | |
8319 | @kindex i386-stub.c | |
8320 | @cindex Intel | |
8321 | @cindex i386 | |
8322 | For Intel 386 and compatible architectures. | |
8323 | ||
8324 | @item m68k-stub.c | |
8325 | @kindex m68k-stub.c | |
8326 | @cindex Motorola 680x0 | |
8327 | @cindex m680x0 | |
8328 | For Motorola 680x0 architectures. | |
8329 | ||
8330 | @item sh-stub.c | |
8331 | @kindex sh-stub.c | |
8332 | @cindex Hitachi | |
8333 | @cindex SH | |
8334 | For Hitachi SH architectures. | |
8335 | ||
8336 | @item sparc-stub.c | |
8337 | @kindex sparc-stub.c | |
8338 | @cindex Sparc | |
8339 | For @sc{sparc} architectures. | |
8340 | ||
8341 | @item sparcl-stub.c | |
8342 | @kindex sparcl-stub.c | |
8343 | @cindex Fujitsu | |
8344 | @cindex SparcLite | |
8345 | For Fujitsu @sc{sparclite} architectures. | |
8346 | ||
8347 | @end table | |
8348 | ||
8349 | The @file{README} file in the @value{GDBN} distribution may list other | |
8350 | recently added stubs. | |
8351 | ||
8352 | @menu | |
8353 | * Stub Contents:: What the stub can do for you | |
8354 | * Bootstrapping:: What you must do for the stub | |
8355 | * Debug Session:: Putting it all together | |
8356 | * Protocol:: Definition of the communication protocol | |
8357 | * Server:: Using the `gdbserver' program | |
8358 | * NetWare:: Using the `gdbserve.nlm' program | |
8359 | @end menu | |
8360 | ||
8361 | @node Stub Contents | |
8362 | @subsubsection What the stub can do for you | |
8363 | ||
8364 | @cindex remote serial stub | |
8365 | The debugging stub for your architecture supplies these three | |
8366 | subroutines: | |
8367 | ||
8368 | @table @code | |
8369 | @item set_debug_traps | |
8370 | @kindex set_debug_traps | |
8371 | @cindex remote serial stub, initialization | |
8372 | This routine arranges for @code{handle_exception} to run when your | |
8373 | program stops. You must call this subroutine explicitly near the | |
8374 | beginning of your program. | |
8375 | ||
8376 | @item handle_exception | |
8377 | @kindex handle_exception | |
8378 | @cindex remote serial stub, main routine | |
8379 | This is the central workhorse, but your program never calls it | |
8380 | explicitly---the setup code arranges for @code{handle_exception} to | |
8381 | run when a trap is triggered. | |
8382 | ||
8383 | @code{handle_exception} takes control when your program stops during | |
8384 | execution (for example, on a breakpoint), and mediates communications | |
8385 | with @value{GDBN} on the host machine. This is where the communications | |
8386 | protocol is implemented; @code{handle_exception} acts as the @value{GDBN} | |
d4f3574e | 8387 | representative on the target machine. It begins by sending summary |
104c1213 JM |
8388 | information on the state of your program, then continues to execute, |
8389 | retrieving and transmitting any information @value{GDBN} needs, until you | |
8390 | execute a @value{GDBN} command that makes your program resume; at that point, | |
8391 | @code{handle_exception} returns control to your own code on the target | |
8392 | machine. | |
8393 | ||
8394 | @item breakpoint | |
8395 | @cindex @code{breakpoint} subroutine, remote | |
8396 | Use this auxiliary subroutine to make your program contain a | |
8397 | breakpoint. Depending on the particular situation, this may be the only | |
8398 | way for @value{GDBN} to get control. For instance, if your target | |
8399 | machine has some sort of interrupt button, you won't need to call this; | |
8400 | pressing the interrupt button transfers control to | |
8401 | @code{handle_exception}---in effect, to @value{GDBN}. On some machines, | |
8402 | simply receiving characters on the serial port may also trigger a trap; | |
8403 | again, in that situation, you don't need to call @code{breakpoint} from | |
8404 | your own program---simply running @samp{target remote} from the host | |
8405 | @value{GDBN} session gets control. | |
8406 | ||
8407 | Call @code{breakpoint} if none of these is true, or if you simply want | |
8408 | to make certain your program stops at a predetermined point for the | |
8409 | start of your debugging session. | |
8410 | @end table | |
8411 | ||
8412 | @node Bootstrapping | |
8413 | @subsubsection What you must do for the stub | |
8414 | ||
8415 | @cindex remote stub, support routines | |
8416 | The debugging stubs that come with @value{GDBN} are set up for a particular | |
8417 | chip architecture, but they have no information about the rest of your | |
8418 | debugging target machine. | |
8419 | ||
8420 | First of all you need to tell the stub how to communicate with the | |
8421 | serial port. | |
8422 | ||
8423 | @table @code | |
8424 | @item int getDebugChar() | |
8425 | @kindex getDebugChar | |
8426 | Write this subroutine to read a single character from the serial port. | |
8427 | It may be identical to @code{getchar} for your target system; a | |
8428 | different name is used to allow you to distinguish the two if you wish. | |
8429 | ||
8430 | @item void putDebugChar(int) | |
8431 | @kindex putDebugChar | |
8432 | Write this subroutine to write a single character to the serial port. | |
8433 | It may be identical to @code{putchar} for your target system; a | |
8434 | different name is used to allow you to distinguish the two if you wish. | |
8435 | @end table | |
8436 | ||
8437 | @cindex control C, and remote debugging | |
8438 | @cindex interrupting remote targets | |
8439 | If you want @value{GDBN} to be able to stop your program while it is | |
8440 | running, you need to use an interrupt-driven serial driver, and arrange | |
8441 | for it to stop when it receives a @code{^C} (@samp{\003}, the control-C | |
8442 | character). That is the character which @value{GDBN} uses to tell the | |
8443 | remote system to stop. | |
8444 | ||
8445 | Getting the debugging target to return the proper status to @value{GDBN} | |
8446 | probably requires changes to the standard stub; one quick and dirty way | |
8447 | is to just execute a breakpoint instruction (the ``dirty'' part is that | |
8448 | @value{GDBN} reports a @code{SIGTRAP} instead of a @code{SIGINT}). | |
8449 | ||
8450 | Other routines you need to supply are: | |
8451 | ||
8452 | @table @code | |
8453 | @item void exceptionHandler (int @var{exception_number}, void *@var{exception_address}) | |
8454 | @kindex exceptionHandler | |
8455 | Write this function to install @var{exception_address} in the exception | |
8456 | handling tables. You need to do this because the stub does not have any | |
8457 | way of knowing what the exception handling tables on your target system | |
8458 | are like (for example, the processor's table might be in @sc{rom}, | |
8459 | containing entries which point to a table in @sc{ram}). | |
8460 | @var{exception_number} is the exception number which should be changed; | |
8461 | its meaning is architecture-dependent (for example, different numbers | |
8462 | might represent divide by zero, misaligned access, etc). When this | |
8463 | exception occurs, control should be transferred directly to | |
8464 | @var{exception_address}, and the processor state (stack, registers, | |
8465 | and so on) should be just as it is when a processor exception occurs. So if | |
8466 | you want to use a jump instruction to reach @var{exception_address}, it | |
8467 | should be a simple jump, not a jump to subroutine. | |
8468 | ||
8469 | For the 386, @var{exception_address} should be installed as an interrupt | |
8470 | gate so that interrupts are masked while the handler runs. The gate | |
8471 | should be at privilege level 0 (the most privileged level). The | |
8472 | @sc{sparc} and 68k stubs are able to mask interrupts themselves without | |
8473 | help from @code{exceptionHandler}. | |
8474 | ||
8475 | @item void flush_i_cache() | |
8476 | @kindex flush_i_cache | |
d4f3574e | 8477 | On @sc{sparc} and @sc{sparclite} only, write this subroutine to flush the |
104c1213 JM |
8478 | instruction cache, if any, on your target machine. If there is no |
8479 | instruction cache, this subroutine may be a no-op. | |
8480 | ||
8481 | On target machines that have instruction caches, @value{GDBN} requires this | |
8482 | function to make certain that the state of your program is stable. | |
8483 | @end table | |
8484 | ||
8485 | @noindent | |
8486 | You must also make sure this library routine is available: | |
8487 | ||
8488 | @table @code | |
8489 | @item void *memset(void *, int, int) | |
8490 | @kindex memset | |
8491 | This is the standard library function @code{memset} that sets an area of | |
8492 | memory to a known value. If you have one of the free versions of | |
8493 | @code{libc.a}, @code{memset} can be found there; otherwise, you must | |
8494 | either obtain it from your hardware manufacturer, or write your own. | |
8495 | @end table | |
8496 | ||
8497 | If you do not use the GNU C compiler, you may need other standard | |
8498 | library subroutines as well; this varies from one stub to another, | |
8499 | but in general the stubs are likely to use any of the common library | |
d4f3574e | 8500 | subroutines which @code{@value{GCC}} generates as inline code. |
104c1213 JM |
8501 | |
8502 | ||
8503 | @node Debug Session | |
8504 | @subsubsection Putting it all together | |
8505 | ||
8506 | @cindex remote serial debugging summary | |
8507 | In summary, when your program is ready to debug, you must follow these | |
8508 | steps. | |
8509 | ||
8510 | @enumerate | |
8511 | @item | |
8512 | Make sure you have the supporting low-level routines | |
8513 | (@pxref{Bootstrapping,,What you must do for the stub}): | |
8514 | @display | |
8515 | @code{getDebugChar}, @code{putDebugChar}, | |
8516 | @code{flush_i_cache}, @code{memset}, @code{exceptionHandler}. | |
8517 | @end display | |
8518 | ||
8519 | @item | |
8520 | Insert these lines near the top of your program: | |
8521 | ||
8522 | @example | |
8523 | set_debug_traps(); | |
8524 | breakpoint(); | |
8525 | @end example | |
8526 | ||
8527 | @item | |
8528 | For the 680x0 stub only, you need to provide a variable called | |
8529 | @code{exceptionHook}. Normally you just use: | |
8530 | ||
8531 | @example | |
8532 | void (*exceptionHook)() = 0; | |
8533 | @end example | |
8534 | ||
d4f3574e | 8535 | @noindent |
104c1213 | 8536 | but if before calling @code{set_debug_traps}, you set it to point to a |
d4f3574e | 8537 | function in your program; that function is called when |
104c1213 JM |
8538 | @code{@value{GDBN}} continues after stopping on a trap (for example, bus |
8539 | error). The function indicated by @code{exceptionHook} is called with | |
8540 | one parameter: an @code{int} which is the exception number. | |
8541 | ||
8542 | @item | |
8543 | Compile and link together: your program, the @value{GDBN} debugging stub for | |
8544 | your target architecture, and the supporting subroutines. | |
8545 | ||
8546 | @item | |
8547 | Make sure you have a serial connection between your target machine and | |
8548 | the @value{GDBN} host, and identify the serial port on the host. | |
8549 | ||
8550 | @item | |
8551 | @c The "remote" target now provides a `load' command, so we should | |
8552 | @c document that. FIXME. | |
8553 | Download your program to your target machine (or get it there by | |
8554 | whatever means the manufacturer provides), and start it. | |
8555 | ||
8556 | @item | |
8557 | To start remote debugging, run @value{GDBN} on the host machine, and specify | |
8558 | as an executable file the program that is running in the remote machine. | |
8559 | This tells @value{GDBN} how to find your program's symbols and the contents | |
8560 | of its pure text. | |
8561 | ||
d4f3574e | 8562 | @item |
104c1213 | 8563 | @cindex serial line, @code{target remote} |
d4f3574e | 8564 | Establish communication using the @code{target remote} command. |
104c1213 JM |
8565 | Its argument specifies how to communicate with the target |
8566 | machine---either via a devicename attached to a direct serial line, or a | |
8567 | TCP port (usually to a terminal server which in turn has a serial line | |
8568 | to the target). For example, to use a serial line connected to the | |
8569 | device named @file{/dev/ttyb}: | |
8570 | ||
8571 | @example | |
8572 | target remote /dev/ttyb | |
8573 | @end example | |
8574 | ||
8575 | @cindex TCP port, @code{target remote} | |
8576 | To use a TCP connection, use an argument of the form | |
8577 | @code{@var{host}:port}. For example, to connect to port 2828 on a | |
8578 | terminal server named @code{manyfarms}: | |
8579 | ||
8580 | @example | |
8581 | target remote manyfarms:2828 | |
8582 | @end example | |
8583 | @end enumerate | |
8584 | ||
8585 | Now you can use all the usual commands to examine and change data and to | |
8586 | step and continue the remote program. | |
8587 | ||
8588 | To resume the remote program and stop debugging it, use the @code{detach} | |
8589 | command. | |
8590 | ||
8591 | @cindex interrupting remote programs | |
8592 | @cindex remote programs, interrupting | |
8593 | Whenever @value{GDBN} is waiting for the remote program, if you type the | |
8594 | interrupt character (often @key{C-C}), @value{GDBN} attempts to stop the | |
8595 | program. This may or may not succeed, depending in part on the hardware | |
8596 | and the serial drivers the remote system uses. If you type the | |
8597 | interrupt character once again, @value{GDBN} displays this prompt: | |
8598 | ||
8599 | @example | |
8600 | Interrupted while waiting for the program. | |
8601 | Give up (and stop debugging it)? (y or n) | |
8602 | @end example | |
8603 | ||
8604 | If you type @kbd{y}, @value{GDBN} abandons the remote debugging session. | |
8605 | (If you decide you want to try again later, you can use @samp{target | |
8606 | remote} again to connect once more.) If you type @kbd{n}, @value{GDBN} | |
8607 | goes back to waiting. | |
8608 | ||
8609 | @node Protocol | |
8610 | @subsubsection Communication protocol | |
8611 | ||
8612 | @cindex debugging stub, example | |
8613 | @cindex remote stub, example | |
8614 | @cindex stub example, remote debugging | |
8615 | The stub files provided with @value{GDBN} implement the target side of the | |
8616 | communication protocol, and the @value{GDBN} side is implemented in the | |
8617 | @value{GDBN} source file @file{remote.c}. Normally, you can simply allow | |
8618 | these subroutines to communicate, and ignore the details. (If you're | |
8619 | implementing your own stub file, you can still ignore the details: start | |
8620 | with one of the existing stub files. @file{sparc-stub.c} is the best | |
8621 | organized, and therefore the easiest to read.) | |
8622 | ||
8623 | However, there may be occasions when you need to know something about | |
8624 | the protocol---for example, if there is only one serial port to your | |
8625 | target machine, you might want your program to do something special if | |
8626 | it recognizes a packet meant for @value{GDBN}. | |
8627 | ||
8628 | In the examples below, @samp{<-} and @samp{->} are used to indicate | |
8629 | transmitted and received data respectfully. | |
8630 | ||
8631 | @cindex protocol, @value{GDBN} remote serial | |
8632 | @cindex serial protocol, @value{GDBN} remote | |
8633 | @cindex remote serial protocol | |
8634 | All @value{GDBN} commands and responses (other than acknowledgments) | |
8635 | are sent as a @var{packet}. A @var{packet} is introduced with the | |
8636 | character @samp{$}, this is followed by an optional two-digit | |
8637 | @var{sequence-id} and the character @samp{:}, the actual | |
8638 | @var{packet-data}, and the terminating character @samp{#} followed by a | |
8639 | two-digit @var{checksum}: | |
8640 | ||
8641 | @example | |
8642 | @code{$}@var{packet-data}@code{#}@var{checksum} | |
8643 | @end example | |
8644 | @noindent | |
8645 | or, with the optional @var{sequence-id}: | |
8646 | @example | |
8647 | @code{$}@var{sequence-id}@code{:}@var{packet-data}@code{#}@var{checksum} | |
8648 | @end example | |
8649 | ||
8650 | @cindex checksum, for @value{GDBN} remote | |
8651 | @noindent | |
8652 | The two-digit @var{checksum} is computed as the modulo 256 sum of all | |
8653 | characters between the leading @samp{$} and the trailing @samp{#} (that | |
8654 | consisting of both the optional @var{sequence-id}@code{:} and the actual | |
d4f3574e | 8655 | @var{packet-data}) (an eight bit unsigned checksum). |
104c1213 JM |
8656 | |
8657 | @cindex sequence-id, for @value{GDBN} remote | |
8658 | @noindent | |
8659 | The two-digit @var{sequence-id}, when present, is returned with the | |
8660 | acknowledgment. Beyond that its meaning is poorly defined. | |
8661 | @value{GDBN} is not known to output @var{sequence-id}s. | |
8662 | ||
8663 | When either the host or the target machine receives a packet, the first | |
8664 | response expected is an acknowledgment: either @samp{+} (to indicate | |
8665 | the package was received correctly) or @samp{-} (to request | |
8666 | retransmission): | |
8667 | ||
8668 | @example | |
8669 | <- @code{$}@var{packet-data}@code{#}@var{checksum} | |
8670 | -> @code{+} | |
8671 | @end example | |
8672 | @noindent | |
8673 | If the received packet included a @var{sequence-id} than that is | |
8674 | appended to a positive acknowledgment: | |
8675 | ||
8676 | @example | |
8677 | <- @code{$}@var{sequence-id}@code{:}@var{packet-data}@code{#}@var{checksum} | |
8678 | -> @code{+}@var{sequence-id} | |
8679 | @end example | |
8680 | ||
8681 | The host (@value{GDBN}) sends @var{command}s, and the target (the | |
8682 | debugging stub incorporated in your program) sends a @var{response}. In | |
8683 | the case of step and continue @var{command}s, the response is only sent | |
8684 | when the operation has completed (the target has again stopped). | |
8685 | ||
8686 | @var{packet-data} consists of a sequence of characters with the | |
8687 | exception of @samp{#} and @samp{$} (see @samp{X} packet for an | |
8688 | exception). @samp{:} can not appear as the third character in a packet. | |
8689 | Fields within the packet should be separated using @samp{,} and @samp{;} | |
8690 | (unfortunately some packets chose to use @samp{:}). Except where | |
8691 | otherwise noted all numbers are represented in HEX with leading zeros | |
8692 | suppressed. | |
8693 | ||
8694 | Response @var{data} can be run-length encoded to save space. A @samp{*} | |
c3f6f71d | 8695 | means that the next character is an @sc{ascii} encoding giving a repeat count |
104c1213 JM |
8696 | which stands for that many repetitions of the character preceding the |
8697 | @samp{*}. The encoding is @code{n+29}, yielding a printable character | |
d4f3574e SS |
8698 | where @code{n >=3} (which is where rle starts to win). The printable |
8699 | characters @samp{$}, @samp{#}, @samp{+} and @samp{-} or with a numeric | |
8700 | value greater than 126 should not be used. | |
8701 | ||
8702 | Some remote systems have used a different run-length encoding mechanism | |
8703 | loosely refered to as the cisco encoding. Following the @samp{*} | |
8704 | character are two hex digits that indicate the size of the packet. | |
104c1213 JM |
8705 | |
8706 | So: | |
8707 | @example | |
8708 | "@code{0* }" | |
8709 | @end example | |
8710 | @noindent | |
8711 | means the same as "0000". | |
8712 | ||
8713 | The error response, returned for some packets includes a two character | |
8714 | error number. That number is not well defined. | |
8715 | ||
8716 | For any @var{command} not supported by the stub, an empty response | |
8717 | (@samp{$#00}) should be returned. That way it is possible to extend the | |
8718 | protocol. A newer @value{GDBN} can tell if a packet is supported based | |
d4f3574e | 8719 | on that response. |
104c1213 JM |
8720 | |
8721 | Below is a complete list of all currently defined @var{command}s and | |
8722 | their corresponding response @var{data}: | |
8723 | ||
8724 | @multitable @columnfractions .30 .30 .40 | |
8725 | @item Packet | |
8726 | @tab Request | |
8727 | @tab Description | |
8728 | ||
8729 | @item extended ops @emph{(optional)} | |
8730 | @tab @code{!} | |
8731 | @tab | |
d4f3574e | 8732 | Use the extended remote protocol. Sticky---only needs to be set once. |
104c1213 JM |
8733 | The extended remote protocol support the @samp{R} packet. |
8734 | @item | |
8735 | @tab reply @samp{} | |
8736 | @tab | |
8737 | Stubs that support the extended remote protocol return @samp{} which, | |
8738 | unfortunately, is identical to the response returned by stubs that do not | |
8739 | support protocol extensions. | |
8740 | ||
8741 | @item last signal | |
8742 | @tab @code{?} | |
8743 | @tab | |
d4f3574e SS |
8744 | Indicate the reason the target halted. The reply is the same as for step |
8745 | and continue. | |
8746 | @item | |
8747 | @tab reply | |
8748 | @tab see below | |
8749 | ||
104c1213 JM |
8750 | |
8751 | @item reserved | |
8752 | @tab @code{a} | |
8753 | @tab Reserved for future use | |
8754 | ||
8755 | @item set program arguments @strong{(reserved)} @emph{(optional)} | |
8756 | @tab @code{A}@var{arglen}@code{,}@var{argnum}@code{,}@var{arg}@code{,...} | |
8757 | @tab | |
8758 | Initialized @samp{argv[]} array passed into program. @var{arglen} | |
8759 | specifies the number of bytes in the hex encoded byte stream @var{arg}. | |
d4f3574e | 8760 | See @file{gdbserver} for more details. |
104c1213 JM |
8761 | @item |
8762 | @tab reply @code{OK} | |
8763 | @item | |
8764 | @tab reply @code{E}@var{NN} | |
8765 | ||
8766 | @item set baud @strong{(deprecated)} | |
8767 | @tab @code{b}@var{baud} | |
8768 | @tab | |
8769 | Change the serial line speed to @var{baud}. JTC: @emph{When does the | |
8770 | transport layer state change? When it's received, or after the ACK is | |
8771 | transmitted. In either case, there are problems if the command or the | |
8772 | acknowledgment packet is dropped.} Stan: @emph{If people really wanted | |
8773 | to add something like this, and get it working for the first time, they | |
8774 | ought to modify ser-unix.c to send some kind of out-of-band message to a | |
8775 | specially-setup stub and have the switch happen "in between" packets, so | |
8776 | that from remote protocol's point of view, nothing actually | |
8777 | happened.} | |
8778 | ||
8779 | @item set breakpoint @strong{(deprecated)} | |
8780 | @tab @code{B}@var{addr},@var{mode} | |
8781 | @tab | |
8782 | Set (@var{mode} is @samp{S}) or clear (@var{mode} is @samp{C}) a | |
8783 | breakpoint at @var{addr}. @emph{This has been replaced by the @samp{Z} and | |
8784 | @samp{z} packets.} | |
8785 | ||
8786 | @item continue | |
8787 | @tab @code{c}@var{addr} | |
8788 | @tab | |
8789 | @var{addr} is address to resume. If @var{addr} is omitted, resume at | |
8790 | current address. | |
8791 | @item | |
8792 | @tab reply | |
8793 | @tab see below | |
8794 | ||
8795 | @item continue with signal @emph{(optional)} | |
8796 | @tab @code{C}@var{sig}@code{;}@var{addr} | |
8797 | @tab | |
8798 | Continue with signal @var{sig} (hex signal number). If | |
8799 | @code{;}@var{addr} is omitted, resume at same address. | |
8800 | @item | |
8801 | @tab reply | |
8802 | @tab see below | |
8803 | ||
d4f3574e | 8804 | @item toggle debug @emph{(deprecated)} |
104c1213 JM |
8805 | @tab @code{d} |
8806 | @tab | |
d4f3574e | 8807 | toggle debug flag. |
104c1213 JM |
8808 | |
8809 | @item detach @emph{(optional)} | |
8810 | @tab @code{D} | |
d4f3574e | 8811 | @tab |
2df3850c JM |
8812 | Detach @value{GDBN} from the remote system. Sent to the remote target before |
8813 | @value{GDBN} disconnects. | |
d4f3574e SS |
8814 | @item |
8815 | @tab reply @emph{no response} | |
8816 | @tab | |
2df3850c | 8817 | @value{GDBN} does not check for any response after sending this packet |
104c1213 JM |
8818 | |
8819 | @item reserved | |
8820 | @tab @code{e} | |
8821 | @tab Reserved for future use | |
8822 | ||
8823 | @item reserved | |
8824 | @tab @code{E} | |
8825 | @tab Reserved for future use | |
8826 | ||
8827 | @item reserved | |
8828 | @tab @code{f} | |
8829 | @tab Reserved for future use | |
8830 | ||
8831 | @item reserved | |
8832 | @tab @code{F} | |
8833 | @tab Reserved for future use | |
8834 | ||
8835 | @item read registers | |
8836 | @tab @code{g} | |
8837 | @tab Read general registers. | |
8838 | @item | |
8839 | @tab reply @var{XX...} | |
8840 | @tab | |
8841 | Each byte of register data is described by two hex digits. The bytes | |
8842 | with the register are transmitted in target byte order. The size of | |
d4f3574e | 8843 | each register and their position within the @samp{g} @var{packet} are |
2df3850c | 8844 | determined by the @value{GDBN} internal macros @var{REGISTER_RAW_SIZE} and |
d4f3574e SS |
8845 | @var{REGISTER_NAME} macros. The specification of several standard |
8846 | @code{g} packets is specified below. | |
104c1213 JM |
8847 | @item |
8848 | @tab @code{E}@var{NN} | |
8849 | @tab for an error. | |
8850 | ||
8851 | @item write regs | |
8852 | @tab @code{G}@var{XX...} | |
8853 | @tab | |
8854 | See @samp{g} for a description of the @var{XX...} data. | |
8855 | @item | |
8856 | @tab reply @code{OK} | |
8857 | @tab for success | |
8858 | @item | |
8859 | @tab reply @code{E}@var{NN} | |
8860 | @tab for an error | |
8861 | ||
8862 | @item reserved | |
8863 | @tab @code{h} | |
8864 | @tab Reserved for future use | |
8865 | ||
8866 | @item set thread @emph{(optional)} | |
8867 | @tab @code{H}@var{c}@var{t...} | |
8868 | @tab | |
d4f3574e SS |
8869 | Set thread for subsequent operations (@samp{m}, @samp{M}, @samp{g}, |
8870 | @samp{G}, et.al.). @var{c} = @samp{c} for thread used in step and | |
8871 | continue; @var{t...} can be -1 for all threads. @var{c} = @samp{g} for | |
8872 | thread used in other operations. If zero, pick a thread, any thread. | |
104c1213 JM |
8873 | @item |
8874 | @tab reply @code{OK} | |
8875 | @tab for success | |
8876 | @item | |
8877 | @tab reply @code{E}@var{NN} | |
8878 | @tab for an error | |
8879 | ||
d4f3574e SS |
8880 | @c FIXME: JTC: |
8881 | @c 'H': How restrictive (or permissive) is the thread model. If a | |
8882 | @c thread is selected and stopped, are other threads allowed | |
8883 | @c to continue to execute? As I mentioned above, I think the | |
8884 | @c semantics of each command when a thread is selected must be | |
8885 | @c described. For example: | |
8886 | @c | |
8887 | @c 'g': If the stub supports threads and a specific thread is | |
8888 | @c selected, returns the register block from that thread; | |
8889 | @c otherwise returns current registers. | |
8890 | @c | |
8891 | @c 'G' If the stub supports threads and a specific thread is | |
8892 | @c selected, sets the registers of the register block of | |
8893 | @c that thread; otherwise sets current registers. | |
8894 | ||
104c1213 JM |
8895 | @item cycle step @strong{(draft)} @emph{(optional)} |
8896 | @tab @code{i}@var{addr}@code{,}@var{nnn} | |
8897 | @tab | |
8898 | Step the remote target by a single clock cycle. If @code{,}@var{nnn} is | |
8899 | present, cycle step @var{nnn} cycles. If @var{addr} is present, cycle | |
8900 | step starting at that address. | |
8901 | ||
8902 | @item signal then cycle step @strong{(reserved)} @emph{(optional)} | |
8903 | @tab @code{I} | |
8904 | @tab | |
8905 | See @samp{i} and @samp{S} for likely syntax and semantics. | |
8906 | ||
8907 | @item reserved | |
8908 | @tab @code{j} | |
8909 | @tab Reserved for future use | |
8910 | ||
8911 | @item reserved | |
8912 | @tab @code{J} | |
8913 | @tab Reserved for future use | |
8914 | ||
8915 | @item kill request @emph{(optional)} | |
8916 | @tab @code{k} | |
8917 | @tab | |
d4f3574e SS |
8918 | FIXME: @emph{There is no description of how operate when a specific |
8919 | thread context has been selected (ie. does 'k' kill only that thread?)}. | |
104c1213 JM |
8920 | |
8921 | @item reserved | |
8922 | @tab @code{l} | |
8923 | @tab Reserved for future use | |
8924 | ||
8925 | @item reserved | |
8926 | @tab @code{L} | |
8927 | @tab Reserved for future use | |
8928 | ||
8929 | @item read memory | |
8930 | @tab @code{m}@var{addr}@code{,}@var{length} | |
8931 | @tab | |
8932 | Read @var{length} bytes of memory starting at address @var{addr}. | |
2df3850c | 8933 | Neither @value{GDBN} nor the stub assume that sized memory transfers are assumed |
d4f3574e SS |
8934 | using word alligned accesses. FIXME: @emph{A word aligned memory |
8935 | transfer mechanism is needed.} | |
104c1213 JM |
8936 | @item |
8937 | @tab reply @var{XX...} | |
8938 | @tab | |
d4f3574e | 8939 | @var{XX...} is mem contents. Can be fewer bytes than requested if able |
2df3850c | 8940 | to read only part of the data. Neither @value{GDBN} nor the stub assume that |
d4f3574e SS |
8941 | sized memory transfers are assumed using word alligned accesses. FIXME: |
8942 | @emph{A word aligned memory transfer mechanism is needed.} | |
104c1213 JM |
8943 | @item |
8944 | @tab reply @code{E}@var{NN} | |
8945 | @tab @var{NN} is errno | |
8946 | ||
8947 | @item write mem | |
8948 | @tab @code{M}@var{addr},@var{length}@code{:}@var{XX...} | |
8949 | @tab | |
8950 | Write @var{length} bytes of memory starting at address @var{addr}. | |
8951 | @var{XX...} is the data. | |
8952 | @item | |
8953 | @tab reply @code{OK} | |
8954 | @tab for success | |
8955 | @item | |
8956 | @tab reply @code{E}@var{NN} | |
8957 | @tab | |
8958 | for an error (this includes the case where only part of the data was | |
8959 | written). | |
8960 | ||
8961 | @item reserved | |
8962 | @tab @code{n} | |
8963 | @tab Reserved for future use | |
8964 | ||
8965 | @item reserved | |
8966 | @tab @code{N} | |
8967 | @tab Reserved for future use | |
8968 | ||
8969 | @item reserved | |
8970 | @tab @code{o} | |
8971 | @tab Reserved for future use | |
8972 | ||
8973 | @item reserved | |
8974 | @tab @code{O} | |
8975 | @tab Reserved for future use | |
8976 | ||
8977 | @item read reg @strong{(reserved)} | |
8978 | @tab @code{p}@var{n...} | |
8979 | @tab | |
8980 | See write register. | |
8981 | @item | |
8982 | @tab return @var{r....} | |
8983 | @tab The hex encoded value of the register in target byte order. | |
8984 | ||
8985 | @item write reg @emph{(optional)} | |
8986 | @tab @code{P}@var{n...}@code{=}@var{r...} | |
8987 | @tab | |
8988 | Write register @var{n...} with value @var{r...}, which contains two hex | |
8989 | digits for each byte in the register (target byte order). | |
8990 | @item | |
8991 | @tab reply @code{OK} | |
8992 | @tab for success | |
8993 | @item | |
8994 | @tab reply @code{E}@var{NN} | |
8995 | @tab for an error | |
8996 | ||
8997 | @item general query @emph{(optional)} | |
8998 | @tab @code{q}@var{query} | |
8999 | @tab | |
d4f3574e | 9000 | Request info about @var{query}. In general @value{GDBN} @var{query}'s |
104c1213 | 9001 | have a leading upper case letter. Custom vendor queries should use a |
d4f3574e SS |
9002 | company prefix (in lower case) ex: @samp{qfsf.var}. @var{query} may |
9003 | optionally be followed by a @samp{,} or @samp{;} separated list. Stubs | |
9004 | must ensure that they match the full @var{query} name. | |
104c1213 JM |
9005 | @item |
9006 | @tab reply @code{XX...} | |
d4f3574e | 9007 | @tab Hex encoded data from query. The reply can not be empty. |
104c1213 JM |
9008 | @item |
9009 | @tab reply @code{E}@var{NN} | |
9010 | @tab error reply | |
9011 | @item | |
9012 | @tab reply @samp{} | |
9013 | @tab Indicating an unrecognized @var{query}. | |
9014 | ||
104c1213 JM |
9015 | @item general set @emph{(optional)} |
9016 | @tab @code{Q}@var{var}@code{=}@var{val} | |
9017 | @tab | |
9018 | Set value of @var{var} to @var{val}. See @samp{q} for a discussing of | |
9019 | naming conventions. | |
9020 | ||
d4f3574e SS |
9021 | @item reset @emph{(deprecated)} |
9022 | @tab @code{r} | |
9023 | @tab | |
9024 | Reset the entire system. | |
104c1213 JM |
9025 | |
9026 | @item remote restart @emph{(optional)} | |
9027 | @tab @code{R}@var{XX} | |
9028 | @tab | |
d4f3574e SS |
9029 | Restart the remote server. @var{XX} while needed has no clear |
9030 | definition. FIXME: @emph{An example interaction explaining how this | |
9031 | packet is used in extended-remote mode is needed}. | |
104c1213 JM |
9032 | |
9033 | @item step @emph{(optional)} | |
9034 | @tab @code{s}@var{addr} | |
9035 | @tab | |
9036 | @var{addr} is address to resume. If @var{addr} is omitted, resume at | |
9037 | same address. | |
9038 | @item | |
9039 | @tab reply | |
9040 | @tab see below | |
9041 | ||
9042 | @item step with signal @emph{(optional)} | |
9043 | @tab @code{S}@var{sig}@code{;}@var{addr} | |
9044 | @tab | |
9045 | Like @samp{C} but step not continue. | |
9046 | @item | |
9047 | @tab reply | |
9048 | @tab see below | |
9049 | ||
9050 | @item search @emph{(optional)} | |
9051 | @tab @code{t}@var{addr}@code{:}@var{PP}@code{,}@var{MM} | |
9052 | @tab | |
9053 | Search backwards starting at address @var{addr} for a match with pattern | |
9054 | @var{PP} and mask @var{MM}. @var{PP} and @var{MM} are 4 | |
d4f3574e | 9055 | bytes. @var{addr} must be at least 3 digits. |
104c1213 JM |
9056 | |
9057 | @item thread alive @emph{(optional)} | |
9058 | @tab @code{T}@var{XX} | |
9059 | @tab Find out if the thread XX is alive. | |
9060 | @item | |
9061 | @tab reply @code{OK} | |
9062 | @tab thread is still alive | |
9063 | @item | |
9064 | @tab reply @code{E}@var{NN} | |
9065 | @tab thread is dead | |
9066 | ||
9067 | @item reserved | |
9068 | @tab @code{u} | |
9069 | @tab Reserved for future use | |
9070 | ||
9071 | @item reserved | |
9072 | @tab @code{U} | |
9073 | @tab Reserved for future use | |
9074 | ||
9075 | @item reserved | |
9076 | @tab @code{v} | |
9077 | @tab Reserved for future use | |
9078 | ||
9079 | @item reserved | |
9080 | @tab @code{V} | |
9081 | @tab Reserved for future use | |
9082 | ||
9083 | @item reserved | |
9084 | @tab @code{w} | |
9085 | @tab Reserved for future use | |
9086 | ||
9087 | @item reserved | |
9088 | @tab @code{W} | |
9089 | @tab Reserved for future use | |
9090 | ||
9091 | @item reserved | |
9092 | @tab @code{x} | |
9093 | @tab Reserved for future use | |
9094 | ||
9095 | @item write mem (binary) @emph{(optional)} | |
9096 | @tab @code{X}@var{addr}@code{,}@var{length}@var{:}@var{XX...} | |
9097 | @tab | |
9098 | @var{addr} is address, @var{length} is number of bytes, @var{XX...} is | |
d4f3574e SS |
9099 | binary data. The characters @code{$}, @code{#}, and @code{0x7d} are |
9100 | escaped using @code{0x7d}. | |
104c1213 JM |
9101 | @item |
9102 | @tab reply @code{OK} | |
9103 | @tab for success | |
9104 | @item | |
9105 | @tab reply @code{E}@var{NN} | |
9106 | @tab for an error | |
9107 | ||
9108 | @item reserved | |
9109 | @tab @code{y} | |
9110 | @tab Reserved for future use | |
9111 | ||
9112 | @item reserved | |
9113 | @tab @code{Y} | |
9114 | @tab Reserved for future use | |
9115 | ||
9116 | @item remove break or watchpoint @strong{(draft)} @emph{(optional)} | |
9117 | @tab @code{z}@var{t}@code{,}@var{addr}@code{,}@var{length} | |
9118 | @tab | |
9119 | See @samp{Z}. | |
9120 | ||
9121 | @item insert break or watchpoint @strong{(draft)} @emph{(optional)} | |
9122 | @tab @code{Z}@var{t}@code{,}@var{addr}@code{,}@var{length} | |
9123 | @tab | |
9124 | @var{t} is type: @samp{0} - software breakpoint, @samp{1} - hardware | |
9125 | breakpoint, @samp{2} - write watchpoint, @samp{3} - read watchpoint, | |
9126 | @samp{4} - access watchpoint; @var{addr} is address; @var{length} is in | |
9127 | bytes. For a software breakpoint, @var{length} specifies the size of | |
9128 | the instruction to be patched. For hardware breakpoints and watchpoints | |
d4f3574e SS |
9129 | @var{length} specifies the memory region to be monitored. To avoid |
9130 | potential problems with duplicate packets, the operations should be | |
9131 | implemented in an ident-potentent way. | |
104c1213 JM |
9132 | @item |
9133 | @tab reply @code{E}@var{NN} | |
9134 | @tab for an error | |
9135 | @item | |
9136 | @tab reply @code{OK} | |
9137 | @tab for success | |
9138 | @item | |
9139 | @tab @samp{} | |
9140 | @tab If not supported. | |
9141 | ||
9142 | @item reserved | |
9143 | @tab <other> | |
9144 | @tab Reserved for future use | |
9145 | ||
9146 | @end multitable | |
9147 | ||
d4f3574e SS |
9148 | The @samp{C}, @samp{c}, @samp{S}, @samp{s} and @samp{?} packets can |
9149 | receive any of the below as a reply. In the case of the @samp{C}, | |
9150 | @samp{c}, @samp{S} and @samp{s} packets, that reply is only returned | |
9151 | when the target halts. In the below the exact meaning of @samp{signal | |
9152 | number} is poorly defined. In general one of the UNIX signal numbering | |
9153 | conventions is used. | |
104c1213 JM |
9154 | |
9155 | @multitable @columnfractions .4 .6 | |
9156 | ||
9157 | @item @code{S}@var{AA} | |
9158 | @tab @var{AA} is the signal number | |
9159 | ||
9160 | @item @code{T}@var{AA}@var{n...}@code{:}@var{r...}@code{;}@var{n...}@code{:}@var{r...}@code{;}@var{n...}@code{:}@var{r...}@code{;} | |
9161 | @tab | |
9162 | @var{AA} = two hex digit signal number; @var{n...} = register number | |
9163 | (hex), @var{r...} = target byte ordered register contents, size defined | |
9164 | by @code{REGISTER_RAW_SIZE}; @var{n...} = @samp{thread}, @var{r...} = | |
9165 | thread process ID, this is a hex integer; @var{n...} = other string not | |
d4f3574e | 9166 | starting with valid hex digit. @value{GDBN} should ignore this |
104c1213 JM |
9167 | @var{n...}, @var{r...} pair and go on to the next. This way we can |
9168 | extend the protocol. | |
9169 | ||
9170 | @item @code{W}@var{AA} | |
9171 | @tab | |
9172 | The process exited, and @var{AA} is the exit status. This is only | |
9173 | applicable for certains sorts of targets. | |
9174 | ||
9175 | @item @code{X}@var{AA} | |
9176 | @tab | |
9177 | The process terminated with signal @var{AA}. | |
9178 | ||
9179 | @item @code{N}@var{AA}@code{;}@var{tttttttt}@code{;}@var{dddddddd}@code{;}@var{bbbbbbbb} @strong{(obsolete)} | |
9180 | @tab | |
9181 | @var{AA} = signal number; @var{tttttttt} = address of symbol "_start"; | |
9182 | @var{dddddddd} = base of data section; @var{bbbbbbbb} = base of bss | |
d4f3574e | 9183 | section. @emph{Note: only used by Cisco Systems targets. The difference |
104c1213 JM |
9184 | between this reply and the "qOffsets" query is that the 'N' packet may |
9185 | arrive spontaneously whereas the 'qOffsets' is a query initiated by the | |
9186 | host debugger.} | |
9187 | ||
9188 | @item @code{O}@var{XX...} | |
9189 | @tab | |
c3f6f71d | 9190 | @var{XX...} is hex encoding of @sc{ascii} data. This can happen at any time |
104c1213 JM |
9191 | while the program is running and the debugger should continue to wait |
9192 | for 'W', 'T', etc. | |
9193 | ||
9194 | @end multitable | |
9195 | ||
d4f3574e SS |
9196 | The following set and query packets have already been defined. |
9197 | ||
9198 | @multitable @columnfractions .2 .2 .6 | |
9199 | ||
9200 | @item current thread | |
9201 | @tab @code{q}@code{C} | |
9202 | @tab Return the current thread id. | |
9203 | @item | |
9204 | @tab reply @code{QC}@var{pid} | |
9205 | @tab | |
9206 | Where @var{pid} is a HEX encoded 16 bit process id. | |
9207 | @item | |
9208 | @tab reply * | |
9209 | @tab Any other reply implies the old pid. | |
9210 | ||
9211 | @item compute CRC of memory block | |
9212 | @tab @code{q}@code{CRC:}@var{addr}@code{,}@var{length} | |
9213 | @tab | |
9214 | @item | |
9215 | @tab reply @code{E}@var{NN} | |
9216 | @tab An error (such as memory fault) | |
9217 | @item | |
9218 | @tab reply @code{C}@var{CRC32} | |
9219 | @tab A 32 bit cyclic redundancy check of the specified memory region. | |
9220 | ||
9221 | @item query @var{LIST} or @var{threadLIST} @strong{(deprecated)} | |
9222 | @tab @code{q}@code{L}@var{startflag}@var{threadcount}@var{nextthread} | |
9223 | @tab | |
9224 | Obtain thread information from RTOS. Where: @var{startflag} (one hex | |
9225 | digit) is one to indicate the first query and zero to indicate a | |
9226 | subsequent query; @var{threadcount} (two hex digits) is the maximum | |
9227 | number of threads the response packet can contain; and @var{nextthread} | |
9228 | (eight hex digits), for subsequent queries (@var{startflag} is zero), is | |
9229 | returned in the response as @var{argthread}. | |
9230 | @item | |
9231 | @tab reply @code{q}@code{M}@var{count}@var{done}@var{argthread}@var{thread...} | |
9232 | @tab | |
9233 | Where: @var{count} (two hex digits) is the number of threads being | |
9234 | returned; @var{done} (one hex digit) is zero to indicate more threads | |
9235 | and one indicates no further threads; @var{argthreadid} (eight hex | |
9236 | digits) is @var{nextthread} from the request packet; @var{thread...} is | |
9237 | a sequence of thread IDs from the target. @var{threadid} (eight hex | |
9238 | digits). See @code{remote.c:parse_threadlist_response()}. | |
9239 | ||
9240 | @item query sect offs | |
9241 | @tab @code{q}@code{Offsets} | |
917317f4 JM |
9242 | @tab |
9243 | Get section offsets that the target used when re-locating the downloaded | |
9244 | image. @emph{Note: while a @code{Bss} offset is included in the | |
9245 | response, @value{GDBN} ignores this and instead applies the @code{Data} | |
9246 | offset to the @code{Bss} section.} | |
d4f3574e SS |
9247 | @item |
9248 | @tab reply @code{Text=}@var{xxx}@code{;Data=}@var{yyy}@code{;Bss=}@var{zzz} | |
9249 | ||
9250 | @item thread info request | |
9251 | @tab @code{q}@code{P}@var{mode}@var{threadid} | |
9252 | @tab | |
9253 | Returns information on @var{threadid}. Where: @var{mode} is a hex | |
9254 | encoded 32 bit mode; @var{threadid} is a hex encoded 64 bit thread ID. | |
9255 | @item | |
9256 | @tab reply * | |
9257 | @tab | |
9258 | See @code{remote.c:remote_unpack_thread_info_response()}. | |
9259 | ||
9260 | @item remote command | |
9261 | @tab @code{q}@code{Rcmd,}@var{COMMAND} | |
9262 | @tab | |
9263 | @var{COMMAND} (hex encoded) is passed to the local interpreter for | |
9264 | execution. Invalid commands should be reported using the output string. | |
9265 | Before the final result packet, the target may also respond with a | |
9266 | number of intermediate @code{O}@var{OUTPUT} console output | |
9267 | packets. @emph{Implementors should note that providing access to a | |
9268 | stubs's interpreter may have security implications}. | |
9269 | @item | |
9270 | @tab reply @code{OK} | |
9271 | @tab | |
9272 | A command response with no output. | |
9273 | @item | |
9274 | @tab reply @var{OUTPUT} | |
9275 | @tab | |
9276 | A command response with the hex encoded output string @var{OUTPUT}. | |
9277 | @item | |
9278 | @tab reply @code{E}@var{NN} | |
9279 | @tab | |
9280 | Indicate a badly formed request. | |
9281 | ||
9282 | @item | |
9283 | @tab reply @samp{} | |
9284 | @tab | |
9285 | When @samp{q}@samp{Rcmd} is not recognized. | |
9286 | ||
9287 | @end multitable | |
9288 | ||
9289 | The following @samp{g}/@samp{G} packets have previously been defined. | |
9290 | In the below, some thirty-two bit registers are transferred as sixty-four | |
9291 | bits. Those registers should be zero/sign extended (which?) to fill the | |
9292 | space allocated. Register bytes are transfered in target byte order. | |
9293 | The two nibbles within a register byte are transfered most-significant - | |
9294 | least-significant. | |
9295 | ||
9296 | @multitable @columnfractions .5 .5 | |
9297 | ||
9298 | @item MIPS32 | |
9299 | @tab | |
9300 | All registers are transfered as thirty-two bit quantities in the order: | |
9301 | 32 general-purpose; sr; lo; hi; bad; cause; pc; 32 floating-point | |
9302 | registers; fsr; fir; fp. | |
9303 | ||
9304 | @item MIPS64 | |
9305 | @tab | |
9306 | All registers are transfered as sixty-four bit quantities (including | |
9307 | thirty-two bit registers such as @code{sr}). The ordering is the same | |
9308 | as @code{MIPS32}. | |
9309 | ||
9310 | @end multitable | |
9311 | ||
104c1213 JM |
9312 | Example sequence of a target being re-started. Notice how the restart |
9313 | does not get any direct output: | |
9314 | ||
9315 | @example | |
9316 | <- @code{R00} | |
9317 | -> @code{+} | |
9318 | @emph{target restarts} | |
9319 | <- @code{?} | |
9320 | -> @code{+} | |
9321 | -> @code{T001:1234123412341234} | |
9322 | <- @code{+} | |
9323 | @end example | |
9324 | ||
9325 | Example sequence of a target being stepped by a single instruction: | |
9326 | ||
9327 | @example | |
9328 | <- @code{G1445...} | |
9329 | -> @code{+} | |
9330 | <- @code{s} | |
9331 | -> @code{+} | |
9332 | @emph{time passes} | |
9333 | -> @code{T001:1234123412341234} | |
9334 | <- @code{+} | |
9335 | <- @code{g} | |
9336 | -> @code{+} | |
9337 | -> @code{1455...} | |
9338 | <- @code{+} | |
9339 | @end example | |
9340 | ||
d4f3574e SS |
9341 | @kindex set remotedebug@r{, serial protocol} |
9342 | @kindex show remotedebug@r{, serial protocol} | |
104c1213 JM |
9343 | @cindex packets, reporting on stdout |
9344 | @cindex serial connections, debugging | |
9345 | If you have trouble with the serial connection, you can use the command | |
9346 | @code{set remotedebug}. This makes @value{GDBN} report on all packets sent | |
9347 | back and forth across the serial line to the remote machine. The | |
9348 | packet-debugging information is printed on the @value{GDBN} standard output | |
9349 | stream. @code{set remotedebug off} turns it off, and @code{show | |
9350 | remotedebug} shows you its current state. | |
9351 | ||
9352 | @node Server | |
9353 | @subsubsection Using the @code{gdbserver} program | |
9354 | ||
9355 | @kindex gdbserver | |
9356 | @cindex remote connection without stubs | |
9357 | @code{gdbserver} is a control program for Unix-like systems, which | |
9358 | allows you to connect your program with a remote @value{GDBN} via | |
9359 | @code{target remote}---but without linking in the usual debugging stub. | |
9360 | ||
9361 | @code{gdbserver} is not a complete replacement for the debugging stubs, | |
9362 | because it requires essentially the same operating-system facilities | |
9363 | that @value{GDBN} itself does. In fact, a system that can run | |
9364 | @code{gdbserver} to connect to a remote @value{GDBN} could also run | |
9365 | @value{GDBN} locally! @code{gdbserver} is sometimes useful nevertheless, | |
9366 | because it is a much smaller program than @value{GDBN} itself. It is | |
9367 | also easier to port than all of @value{GDBN}, so you may be able to get | |
9368 | started more quickly on a new system by using @code{gdbserver}. | |
9369 | Finally, if you develop code for real-time systems, you may find that | |
9370 | the tradeoffs involved in real-time operation make it more convenient to | |
9371 | do as much development work as possible on another system, for example | |
9372 | by cross-compiling. You can use @code{gdbserver} to make a similar | |
9373 | choice for debugging. | |
9374 | ||
9375 | @value{GDBN} and @code{gdbserver} communicate via either a serial line | |
9376 | or a TCP connection, using the standard @value{GDBN} remote serial | |
9377 | protocol. | |
9378 | ||
9379 | @table @emph | |
9380 | @item On the target machine, | |
9381 | you need to have a copy of the program you want to debug. | |
9382 | @code{gdbserver} does not need your program's symbol table, so you can | |
9383 | strip the program if necessary to save space. @value{GDBN} on the host | |
9384 | system does all the symbol handling. | |
9385 | ||
9386 | To use the server, you must tell it how to communicate with @value{GDBN}; | |
9387 | the name of your program; and the arguments for your program. The | |
9388 | syntax is: | |
9389 | ||
9390 | @smallexample | |
9391 | target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ] | |
9392 | @end smallexample | |
9393 | ||
9394 | @var{comm} is either a device name (to use a serial line) or a TCP | |
9395 | hostname and portnumber. For example, to debug Emacs with the argument | |
9396 | @samp{foo.txt} and communicate with @value{GDBN} over the serial port | |
9397 | @file{/dev/com1}: | |
9398 | ||
9399 | @smallexample | |
9400 | target> gdbserver /dev/com1 emacs foo.txt | |
9401 | @end smallexample | |
9402 | ||
9403 | @code{gdbserver} waits passively for the host @value{GDBN} to communicate | |
9404 | with it. | |
9405 | ||
9406 | To use a TCP connection instead of a serial line: | |
9407 | ||
9408 | @smallexample | |
9409 | target> gdbserver host:2345 emacs foo.txt | |
9410 | @end smallexample | |
9411 | ||
9412 | The only difference from the previous example is the first argument, | |
9413 | specifying that you are communicating with the host @value{GDBN} via | |
9414 | TCP. The @samp{host:2345} argument means that @code{gdbserver} is to | |
9415 | expect a TCP connection from machine @samp{host} to local TCP port 2345. | |
9416 | (Currently, the @samp{host} part is ignored.) You can choose any number | |
9417 | you want for the port number as long as it does not conflict with any | |
9418 | TCP ports already in use on the target system (for example, @code{23} is | |
9419 | reserved for @code{telnet}).@footnote{If you choose a port number that | |
9420 | conflicts with another service, @code{gdbserver} prints an error message | |
d4f3574e | 9421 | and exits.} You must use the same port number with the host @value{GDBN} |
104c1213 JM |
9422 | @code{target remote} command. |
9423 | ||
9424 | @item On the @value{GDBN} host machine, | |
9425 | you need an unstripped copy of your program, since @value{GDBN} needs | |
9426 | symbols and debugging information. Start up @value{GDBN} as usual, | |
9427 | using the name of the local copy of your program as the first argument. | |
9428 | (You may also need the @w{@samp{--baud}} option if the serial line is | |
d4f3574e | 9429 | running at anything other than 9600@dmn{bps}.) After that, use @code{target |
104c1213 JM |
9430 | remote} to establish communications with @code{gdbserver}. Its argument |
9431 | is either a device name (usually a serial device, like | |
9432 | @file{/dev/ttyb}), or a TCP port descriptor in the form | |
9433 | @code{@var{host}:@var{PORT}}. For example: | |
9434 | ||
9435 | @smallexample | |
9436 | (@value{GDBP}) target remote /dev/ttyb | |
9437 | @end smallexample | |
9438 | ||
9439 | @noindent | |
9440 | communicates with the server via serial line @file{/dev/ttyb}, and | |
9441 | ||
9442 | @smallexample | |
9443 | (@value{GDBP}) target remote the-target:2345 | |
9444 | @end smallexample | |
9445 | ||
9446 | @noindent | |
9447 | communicates via a TCP connection to port 2345 on host @w{@file{the-target}}. | |
9448 | For TCP connections, you must start up @code{gdbserver} prior to using | |
9449 | the @code{target remote} command. Otherwise you may get an error whose | |
9450 | text depends on the host system, but which usually looks something like | |
9451 | @samp{Connection refused}. | |
9452 | @end table | |
9453 | ||
9454 | @node NetWare | |
9455 | @subsubsection Using the @code{gdbserve.nlm} program | |
9456 | ||
9457 | @kindex gdbserve.nlm | |
9458 | @code{gdbserve.nlm} is a control program for NetWare systems, which | |
9459 | allows you to connect your program with a remote @value{GDBN} via | |
9460 | @code{target remote}. | |
9461 | ||
9462 | @value{GDBN} and @code{gdbserve.nlm} communicate via a serial line, | |
9463 | using the standard @value{GDBN} remote serial protocol. | |
9464 | ||
9465 | @table @emph | |
9466 | @item On the target machine, | |
9467 | you need to have a copy of the program you want to debug. | |
9468 | @code{gdbserve.nlm} does not need your program's symbol table, so you | |
9469 | can strip the program if necessary to save space. @value{GDBN} on the | |
9470 | host system does all the symbol handling. | |
9471 | ||
9472 | To use the server, you must tell it how to communicate with | |
9473 | @value{GDBN}; the name of your program; and the arguments for your | |
9474 | program. The syntax is: | |
9475 | ||
9476 | @smallexample | |
9477 | load gdbserve [ BOARD=@var{board} ] [ PORT=@var{port} ] | |
9478 | [ BAUD=@var{baud} ] @var{program} [ @var{args} @dots{} ] | |
9479 | @end smallexample | |
9480 | ||
9481 | @var{board} and @var{port} specify the serial line; @var{baud} specifies | |
9482 | the baud rate used by the connection. @var{port} and @var{node} default | |
d4f3574e | 9483 | to 0, @var{baud} defaults to 9600@dmn{bps}. |
104c1213 JM |
9484 | |
9485 | For example, to debug Emacs with the argument @samp{foo.txt}and | |
9486 | communicate with @value{GDBN} over serial port number 2 or board 1 | |
d4f3574e | 9487 | using a 19200@dmn{bps} connection: |
104c1213 JM |
9488 | |
9489 | @smallexample | |
9490 | load gdbserve BOARD=1 PORT=2 BAUD=19200 emacs foo.txt | |
9491 | @end smallexample | |
9492 | ||
9493 | @item On the @value{GDBN} host machine, | |
9494 | you need an unstripped copy of your program, since @value{GDBN} needs | |
9495 | symbols and debugging information. Start up @value{GDBN} as usual, | |
9496 | using the name of the local copy of your program as the first argument. | |
9497 | (You may also need the @w{@samp{--baud}} option if the serial line is | |
d4f3574e | 9498 | running at anything other than 9600@dmn{bps}. After that, use @code{target |
104c1213 JM |
9499 | remote} to establish communications with @code{gdbserve.nlm}. Its |
9500 | argument is a device name (usually a serial device, like | |
9501 | @file{/dev/ttyb}). For example: | |
9502 | ||
9503 | @smallexample | |
9504 | (@value{GDBP}) target remote /dev/ttyb | |
9505 | @end smallexample | |
9506 | ||
9507 | @noindent | |
9508 | communications with the server via serial line @file{/dev/ttyb}. | |
9509 | @end table | |
9510 | ||
9511 | @node KOD | |
9512 | @section Kernel Object Display | |
9513 | ||
9514 | @cindex kernel object display | |
9515 | @cindex kernel object | |
9516 | @cindex KOD | |
9517 | ||
9518 | Some targets support kernel object display. Using this facility, | |
9519 | @value{GDBN} communicates specially with the underlying operating system | |
9520 | and can display information about operating system-level objects such as | |
9521 | mutexes and other synchronization objects. Exactly which objects can be | |
9522 | displayed is determined on a per-OS basis. | |
9523 | ||
9524 | Use the @code{set os} command to set the operating system. This tells | |
9525 | @value{GDBN} which kernel object display module to initialize: | |
9526 | ||
9527 | @example | |
2df3850c | 9528 | (@value{GDBP}) set os cisco |
104c1213 JM |
9529 | @end example |
9530 | ||
9531 | If @code{set os} succeeds, @value{GDBN} will display some information | |
9532 | about the operating system, and will create a new @code{info} command | |
9533 | which can be used to query the target. The @code{info} command is named | |
9534 | after the operating system: | |
9535 | ||
9536 | @example | |
2df3850c | 9537 | (@value{GDBP}) info cisco |
104c1213 JM |
9538 | List of Cisco Kernel Objects |
9539 | Object Description | |
9540 | any Any and all objects | |
9541 | @end example | |
9542 | ||
9543 | Further subcommands can be used to query about particular objects known | |
9544 | by the kernel. | |
9545 | ||
9546 | There is currently no way to determine whether a given operating system | |
96baa820 JM |
9547 | is supported other than to try it. |
9548 | ||
9549 | ||
104c1213 JM |
9550 | @node Configurations |
9551 | @chapter Configuration-Specific Information | |
9552 | ||
9553 | While nearly all @value{GDBN} commands are available for all native and | |
9554 | cross versions of the debugger, there are some exceptions. This chapter | |
9555 | describes things that are only available in certain configurations. | |
9556 | ||
9557 | There are three major categories of configurations: native | |
9558 | configurations, where the host and target are the same, embedded | |
9559 | operating system configurations, which are usually the same for several | |
9560 | different processor architectures, and bare embedded processors, which | |
9561 | are quite different from each other. | |
9562 | ||
9563 | @menu | |
9564 | * Native:: | |
9565 | * Embedded OS:: | |
9566 | * Embedded Processors:: | |
9567 | * Architectures:: | |
9568 | @end menu | |
9569 | ||
9570 | @node Native | |
9571 | @section Native | |
9572 | ||
9573 | This section describes details specific to particular native | |
9574 | configurations. | |
9575 | ||
9576 | @menu | |
9577 | * HP-UX:: HP-UX | |
9578 | * SVR4 Process Information:: SVR4 process information | |
9579 | @end menu | |
9580 | ||
9581 | @node HP-UX | |
9582 | @subsection HP-UX | |
9583 | ||
9584 | On HP-UX systems, if you refer to a function or variable name that | |
9585 | begins with a dollar sign, @value{GDBN} searches for a user or system | |
9586 | name first, before it searches for a convenience variable. | |
9587 | ||
9588 | @node SVR4 Process Information | |
9589 | @subsection SVR4 process information | |
9590 | ||
9591 | @kindex /proc | |
9592 | @cindex process image | |
9593 | ||
9594 | Many versions of SVR4 provide a facility called @samp{/proc} that can be | |
9595 | used to examine the image of a running process using file-system | |
9596 | subroutines. If @value{GDBN} is configured for an operating system with | |
9597 | this facility, the command @code{info proc} is available to report on | |
9598 | several kinds of information about the process running your program. | |
9599 | @code{info proc} works only on SVR4 systems that include the | |
9600 | @code{procfs} code. This includes OSF/1 (Digital Unix), Solaris, Irix, | |
9601 | and Unixware, but not HP-UX or Linux, for example. | |
9602 | ||
9603 | @table @code | |
9604 | @kindex info proc | |
9605 | @item info proc | |
9606 | Summarize available information about the process. | |
9607 | ||
9608 | @kindex info proc mappings | |
9609 | @item info proc mappings | |
9610 | Report on the address ranges accessible in the program, with information | |
9611 | on whether your program may read, write, or execute each range. | |
9612 | ||
9613 | @kindex info proc times | |
9614 | @item info proc times | |
9615 | Starting time, user CPU time, and system CPU time for your program and | |
9616 | its children. | |
9617 | ||
9618 | @kindex info proc id | |
9619 | @item info proc id | |
9620 | Report on the process IDs related to your program: its own process ID, | |
9621 | the ID of its parent, the process group ID, and the session ID. | |
9622 | ||
9623 | @kindex info proc status | |
9624 | @item info proc status | |
9625 | General information on the state of the process. If the process is | |
9626 | stopped, this report includes the reason for stopping, and any signal | |
9627 | received. | |
9628 | ||
9629 | @item info proc all | |
9630 | Show all the above information about the process. | |
9631 | @end table | |
9632 | ||
9633 | @node Embedded OS | |
9634 | @section Embedded Operating Systems | |
9635 | ||
9636 | This section describes configurations involving the debugging of | |
9637 | embedded operating systems that are available for several different | |
9638 | architectures. | |
9639 | ||
9640 | @menu | |
9641 | * VxWorks:: Using @value{GDBN} with VxWorks | |
9642 | @end menu | |
9643 | ||
9644 | @value{GDBN} includes the ability to debug programs running on | |
9645 | various real-time operating systems. | |
9646 | ||
9647 | @node VxWorks | |
9648 | @subsection Using @value{GDBN} with VxWorks | |
9649 | ||
9650 | @cindex VxWorks | |
9651 | ||
9652 | @table @code | |
9653 | ||
9654 | @kindex target vxworks | |
9655 | @item target vxworks @var{machinename} | |
9656 | A VxWorks system, attached via TCP/IP. The argument @var{machinename} | |
9657 | is the target system's machine name or IP address. | |
9658 | ||
9659 | @end table | |
9660 | ||
9661 | On VxWorks, @code{load} links @var{filename} dynamically on the | |
9662 | current target system as well as adding its symbols in @value{GDBN}. | |
9663 | ||
9664 | @value{GDBN} enables developers to spawn and debug tasks running on networked | |
9665 | VxWorks targets from a Unix host. Already-running tasks spawned from | |
9666 | the VxWorks shell can also be debugged. @value{GDBN} uses code that runs on | |
9667 | both the Unix host and on the VxWorks target. The program | |
d4f3574e | 9668 | @code{@value{GDBP}} is installed and executed on the Unix host. (It may be |
104c1213 | 9669 | installed with the name @code{vxgdb}, to distinguish it from a |
d4f3574e | 9670 | @value{GDB} for debugging programs on the host itself.) |
104c1213 JM |
9671 | |
9672 | @table @code | |
9673 | @item VxWorks-timeout @var{args} | |
9674 | @kindex vxworks-timeout | |
9675 | All VxWorks-based targets now support the option @code{vxworks-timeout}. | |
9676 | This option is set by the user, and @var{args} represents the number of | |
9677 | seconds @value{GDBN} waits for responses to rpc's. You might use this if | |
9678 | your VxWorks target is a slow software simulator or is on the far side | |
9679 | of a thin network line. | |
9680 | @end table | |
9681 | ||
9682 | The following information on connecting to VxWorks was current when | |
9683 | this manual was produced; newer releases of VxWorks may use revised | |
9684 | procedures. | |
9685 | ||
9686 | @kindex INCLUDE_RDB | |
9687 | To use @value{GDBN} with VxWorks, you must rebuild your VxWorks kernel | |
9688 | to include the remote debugging interface routines in the VxWorks | |
9689 | library @file{rdb.a}. To do this, define @code{INCLUDE_RDB} in the | |
9690 | VxWorks configuration file @file{configAll.h} and rebuild your VxWorks | |
9691 | kernel. The resulting kernel contains @file{rdb.a}, and spawns the | |
9692 | source debugging task @code{tRdbTask} when VxWorks is booted. For more | |
9693 | information on configuring and remaking VxWorks, see the manufacturer's | |
9694 | manual. | |
9695 | @c VxWorks, see the @cite{VxWorks Programmer's Guide}. | |
9696 | ||
9697 | Once you have included @file{rdb.a} in your VxWorks system image and set | |
9698 | your Unix execution search path to find @value{GDBN}, you are ready to | |
d4f3574e | 9699 | run @value{GDBN}. From your Unix host, run @code{@value{GDBP}} (or @code{vxgdb}, |
104c1213 JM |
9700 | depending on your installation). |
9701 | ||
9702 | @value{GDBN} comes up showing the prompt: | |
9703 | ||
9704 | @example | |
9705 | (vxgdb) | |
9706 | @end example | |
9707 | ||
9708 | @menu | |
9709 | * VxWorks Connection:: Connecting to VxWorks | |
9710 | * VxWorks Download:: VxWorks download | |
9711 | * VxWorks Attach:: Running tasks | |
9712 | @end menu | |
9713 | ||
9714 | @node VxWorks Connection | |
9715 | @subsubsection Connecting to VxWorks | |
9716 | ||
9717 | The @value{GDBN} command @code{target} lets you connect to a VxWorks target on the | |
9718 | network. To connect to a target whose host name is ``@code{tt}'', type: | |
9719 | ||
9720 | @example | |
9721 | (vxgdb) target vxworks tt | |
9722 | @end example | |
9723 | ||
9724 | @need 750 | |
9725 | @value{GDBN} displays messages like these: | |
9726 | ||
9727 | @smallexample | |
9728 | Attaching remote machine across net... | |
9729 | Connected to tt. | |
9730 | @end smallexample | |
9731 | ||
9732 | @need 1000 | |
9733 | @value{GDBN} then attempts to read the symbol tables of any object modules | |
9734 | loaded into the VxWorks target since it was last booted. @value{GDBN} locates | |
9735 | these files by searching the directories listed in the command search | |
9736 | path (@pxref{Environment, ,Your program's environment}); if it fails | |
9737 | to find an object file, it displays a message such as: | |
9738 | ||
9739 | @example | |
9740 | prog.o: No such file or directory. | |
9741 | @end example | |
9742 | ||
9743 | When this happens, add the appropriate directory to the search path with | |
9744 | the @value{GDBN} command @code{path}, and execute the @code{target} | |
9745 | command again. | |
9746 | ||
9747 | @node VxWorks Download | |
9748 | @subsubsection VxWorks download | |
9749 | ||
9750 | @cindex download to VxWorks | |
9751 | If you have connected to the VxWorks target and you want to debug an | |
9752 | object that has not yet been loaded, you can use the @value{GDBN} | |
9753 | @code{load} command to download a file from Unix to VxWorks | |
9754 | incrementally. The object file given as an argument to the @code{load} | |
9755 | command is actually opened twice: first by the VxWorks target in order | |
9756 | to download the code, then by @value{GDBN} in order to read the symbol | |
9757 | table. This can lead to problems if the current working directories on | |
9758 | the two systems differ. If both systems have NFS mounted the same | |
9759 | filesystems, you can avoid these problems by using absolute paths. | |
9760 | Otherwise, it is simplest to set the working directory on both systems | |
9761 | to the directory in which the object file resides, and then to reference | |
9762 | the file by its name, without any path. For instance, a program | |
9763 | @file{prog.o} may reside in @file{@var{vxpath}/vw/demo/rdb} in VxWorks | |
9764 | and in @file{@var{hostpath}/vw/demo/rdb} on the host. To load this | |
9765 | program, type this on VxWorks: | |
9766 | ||
9767 | @example | |
9768 | -> cd "@var{vxpath}/vw/demo/rdb" | |
9769 | @end example | |
d4f3574e SS |
9770 | |
9771 | @noindent | |
104c1213 JM |
9772 | Then, in @value{GDBN}, type: |
9773 | ||
9774 | @example | |
9775 | (vxgdb) cd @var{hostpath}/vw/demo/rdb | |
9776 | (vxgdb) load prog.o | |
9777 | @end example | |
9778 | ||
9779 | @value{GDBN} displays a response similar to this: | |
9780 | ||
9781 | @smallexample | |
9782 | Reading symbol data from wherever/vw/demo/rdb/prog.o... done. | |
9783 | @end smallexample | |
9784 | ||
9785 | You can also use the @code{load} command to reload an object module | |
9786 | after editing and recompiling the corresponding source file. Note that | |
9787 | this makes @value{GDBN} delete all currently-defined breakpoints, | |
9788 | auto-displays, and convenience variables, and to clear the value | |
9789 | history. (This is necessary in order to preserve the integrity of | |
d4f3574e | 9790 | debugger's data structures that reference the target system's symbol |
104c1213 JM |
9791 | table.) |
9792 | ||
9793 | @node VxWorks Attach | |
9794 | @subsubsection Running tasks | |
9795 | ||
9796 | @cindex running VxWorks tasks | |
9797 | You can also attach to an existing task using the @code{attach} command as | |
9798 | follows: | |
9799 | ||
9800 | @example | |
9801 | (vxgdb) attach @var{task} | |
9802 | @end example | |
9803 | ||
9804 | @noindent | |
9805 | where @var{task} is the VxWorks hexadecimal task ID. The task can be running | |
9806 | or suspended when you attach to it. Running tasks are suspended at | |
9807 | the time of attachment. | |
9808 | ||
9809 | @node Embedded Processors | |
9810 | @section Embedded Processors | |
9811 | ||
9812 | This section goes into details specific to particular embedded | |
9813 | configurations. | |
9814 | ||
9815 | @menu | |
9816 | * A29K Embedded:: AMD A29K Embedded | |
9817 | * ARM:: ARM | |
9818 | * H8/300:: Hitachi H8/300 | |
9819 | * H8/500:: Hitachi H8/500 | |
9820 | * i960:: Intel i960 | |
9821 | * M32R/D:: Mitsubishi M32R/D | |
9822 | * M68K:: Motorola M68K | |
9823 | * M88K:: Motorola M88K | |
9824 | * MIPS Embedded:: MIPS Embedded | |
9825 | * PA:: HP PA Embedded | |
9826 | * PowerPC: PowerPC | |
9827 | * SH:: Hitachi SH | |
9828 | * Sparclet:: Tsqware Sparclet | |
9829 | * Sparclite:: Fujitsu Sparclite | |
9830 | * ST2000:: Tandem ST2000 | |
9831 | * Z8000:: Zilog Z8000 | |
9832 | @end menu | |
9833 | ||
9834 | @node A29K Embedded | |
9835 | @subsection AMD A29K Embedded | |
9836 | ||
9837 | @menu | |
9838 | * A29K UDI:: | |
9839 | * A29K EB29K:: | |
9840 | * Comms (EB29K):: Communications setup | |
9841 | * gdb-EB29K:: EB29K cross-debugging | |
9842 | * Remote Log:: Remote log | |
9843 | @end menu | |
9844 | ||
9845 | @table @code | |
9846 | ||
9847 | @kindex target adapt | |
9848 | @item target adapt @var{dev} | |
9849 | Adapt monitor for A29K. | |
9850 | ||
9851 | @kindex target amd-eb | |
9852 | @item target amd-eb @var{dev} @var{speed} @var{PROG} | |
9853 | @cindex AMD EB29K | |
9854 | Remote PC-resident AMD EB29K board, attached over serial lines. | |
9855 | @var{dev} is the serial device, as for @code{target remote}; | |
9856 | @var{speed} allows you to specify the linespeed; and @var{PROG} is the | |
9857 | name of the program to be debugged, as it appears to DOS on the PC. | |
9858 | @xref{A29K EB29K, ,EBMON protocol for AMD29K}. | |
9859 | ||
9860 | @end table | |
9861 | ||
9862 | @node A29K UDI | |
9863 | @subsubsection A29K UDI | |
9864 | ||
9865 | @cindex UDI | |
9866 | @cindex AMD29K via UDI | |
9867 | ||
9868 | @value{GDBN} supports AMD's UDI (``Universal Debugger Interface'') | |
9869 | protocol for debugging the a29k processor family. To use this | |
9870 | configuration with AMD targets running the MiniMON monitor, you need the | |
9871 | program @code{MONTIP}, available from AMD at no charge. You can also | |
9872 | use @value{GDBN} with the UDI-conformant a29k simulator program | |
9873 | @code{ISSTIP}, also available from AMD. | |
9874 | ||
9875 | @table @code | |
9876 | @item target udi @var{keyword} | |
9877 | @kindex udi | |
9878 | Select the UDI interface to a remote a29k board or simulator, where | |
9879 | @var{keyword} is an entry in the AMD configuration file @file{udi_soc}. | |
9880 | This file contains keyword entries which specify parameters used to | |
9881 | connect to a29k targets. If the @file{udi_soc} file is not in your | |
9882 | working directory, you must set the environment variable @samp{UDICONF} | |
9883 | to its pathname. | |
9884 | @end table | |
9885 | ||
9886 | @node A29K EB29K | |
9887 | @subsubsection EBMON protocol for AMD29K | |
9888 | ||
9889 | @cindex EB29K board | |
9890 | @cindex running 29K programs | |
9891 | ||
9892 | AMD distributes a 29K development board meant to fit in a PC, together | |
9893 | with a DOS-hosted monitor program called @code{EBMON}. As a shorthand | |
9894 | term, this development system is called the ``EB29K''. To use | |
9895 | @value{GDBN} from a Unix system to run programs on the EB29K board, you | |
9896 | must first connect a serial cable between the PC (which hosts the EB29K | |
9897 | board) and a serial port on the Unix system. In the following, we | |
9898 | assume you've hooked the cable between the PC's @file{COM1} port and | |
9899 | @file{/dev/ttya} on the Unix system. | |
9900 | ||
9901 | @node Comms (EB29K) | |
9902 | @subsubsection Communications setup | |
9903 | ||
9904 | The next step is to set up the PC's port, by doing something like this | |
9905 | in DOS on the PC: | |
9906 | ||
9907 | @example | |
9908 | C:\> MODE com1:9600,n,8,1,none | |
9909 | @end example | |
9910 | ||
9911 | @noindent | |
9912 | This example---run on an MS DOS 4.0 system---sets the PC port to 9600 | |
9913 | bps, no parity, eight data bits, one stop bit, and no ``retry'' action; | |
9914 | you must match the communications parameters when establishing the Unix | |
9915 | end of the connection as well. | |
9916 | @c FIXME: Who knows what this "no retry action" crud from the DOS manual may | |
9917 | @c mean? It's optional; leave it out? ---doc@cygnus.com, 25feb91 | |
d4f3574e SS |
9918 | @c |
9919 | @c It's optional, but it's unwise to omit it: who knows what is the | |
9920 | @c default value set when the DOS machines boots? "No retry" means that | |
9921 | @c the DOS serial device driver won't retry the operation if it fails; | |
9922 | @c I understand that this is needed because the GDB serial protocol | |
9923 | @c handles any errors and retransmissions itself. ---Eli Zaretskii, 3sep99 | |
104c1213 JM |
9924 | |
9925 | To give control of the PC to the Unix side of the serial line, type | |
9926 | the following at the DOS console: | |
9927 | ||
9928 | @example | |
9929 | C:\> CTTY com1 | |
9930 | @end example | |
9931 | ||
9932 | @noindent | |
9933 | (Later, if you wish to return control to the DOS console, you can use | |
9934 | the command @code{CTTY con}---but you must send it over the device that | |
9935 | had control, in our example over the @file{COM1} serial line). | |
9936 | ||
9937 | From the Unix host, use a communications program such as @code{tip} or | |
9938 | @code{cu} to communicate with the PC; for example, | |
9939 | ||
9940 | @example | |
9941 | cu -s 9600 -l /dev/ttya | |
9942 | @end example | |
9943 | ||
9944 | @noindent | |
9945 | The @code{cu} options shown specify, respectively, the linespeed and the | |
9946 | serial port to use. If you use @code{tip} instead, your command line | |
9947 | may look something like the following: | |
9948 | ||
9949 | @example | |
9950 | tip -9600 /dev/ttya | |
9951 | @end example | |
9952 | ||
9953 | @noindent | |
9954 | Your system may require a different name where we show | |
9955 | @file{/dev/ttya} as the argument to @code{tip}. The communications | |
9956 | parameters, including which port to use, are associated with the | |
9957 | @code{tip} argument in the ``remote'' descriptions file---normally the | |
9958 | system table @file{/etc/remote}. | |
9959 | @c FIXME: What if anything needs doing to match the "n,8,1,none" part of | |
9960 | @c the DOS side's comms setup? cu can support -o (odd | |
9961 | @c parity), -e (even parity)---apparently no settings for no parity or | |
9962 | @c for character size. Taken from stty maybe...? John points out tip | |
9963 | @c can set these as internal variables, eg ~s parity=none; man stty | |
9964 | @c suggests that it *might* work to stty these options with stdin or | |
9965 | @c stdout redirected... ---doc@cygnus.com, 25feb91 | |
d4f3574e SS |
9966 | @c |
9967 | @c There's nothing to be done for the "none" part of the DOS MODE | |
9968 | @c command. The rest of the parameters should be matched by the | |
9969 | @c baudrate, bits, and parity used by the Unix side. ---Eli Zaretskii, 3Sep99 | |
104c1213 JM |
9970 | |
9971 | @kindex EBMON | |
9972 | Using the @code{tip} or @code{cu} connection, change the DOS working | |
9973 | directory to the directory containing a copy of your 29K program, then | |
9974 | start the PC program @code{EBMON} (an EB29K control program supplied | |
9975 | with your board by AMD). You should see an initial display from | |
9976 | @code{EBMON} similar to the one that follows, ending with the | |
9977 | @code{EBMON} prompt @samp{#}--- | |
9978 | ||
9979 | @example | |
9980 | C:\> G: | |
9981 | ||
9982 | G:\> CD \usr\joe\work29k | |
9983 | ||
9984 | G:\USR\JOE\WORK29K> EBMON | |
9985 | Am29000 PC Coprocessor Board Monitor, version 3.0-18 | |
9986 | Copyright 1990 Advanced Micro Devices, Inc. | |
9987 | Written by Gibbons and Associates, Inc. | |
9988 | ||
9989 | Enter '?' or 'H' for help | |
9990 | ||
9991 | PC Coprocessor Type = EB29K | |
9992 | I/O Base = 0x208 | |
9993 | Memory Base = 0xd0000 | |
9994 | ||
9995 | Data Memory Size = 2048KB | |
9996 | Available I-RAM Range = 0x8000 to 0x1fffff | |
9997 | Available D-RAM Range = 0x80002000 to 0x801fffff | |
9998 | ||
9999 | PageSize = 0x400 | |
10000 | Register Stack Size = 0x800 | |
10001 | Memory Stack Size = 0x1800 | |
10002 | ||
10003 | CPU PRL = 0x3 | |
10004 | Am29027 Available = No | |
10005 | Byte Write Available = Yes | |
10006 | ||
10007 | # ~. | |
10008 | @end example | |
10009 | ||
10010 | Then exit the @code{cu} or @code{tip} program (done in the example by | |
10011 | typing @code{~.} at the @code{EBMON} prompt). @code{EBMON} keeps | |
10012 | running, ready for @value{GDBN} to take over. | |
10013 | ||
10014 | For this example, we've assumed what is probably the most convenient | |
10015 | way to make sure the same 29K program is on both the PC and the Unix | |
d4f3574e | 10016 | system: a PC/NFS connection that establishes ``drive @file{G:}'' on the |
104c1213 JM |
10017 | PC as a file system on the Unix host. If you do not have PC/NFS or |
10018 | something similar connecting the two systems, you must arrange some | |
10019 | other way---perhaps floppy-disk transfer---of getting the 29K program | |
10020 | from the Unix system to the PC; @value{GDBN} does @emph{not} download it over the | |
10021 | serial line. | |
10022 | ||
10023 | @node gdb-EB29K | |
10024 | @subsubsection EB29K cross-debugging | |
10025 | ||
10026 | Finally, @code{cd} to the directory containing an image of your 29K | |
10027 | program on the Unix system, and start @value{GDBN}---specifying as argument the | |
10028 | name of your 29K program: | |
10029 | ||
10030 | @example | |
10031 | cd /usr/joe/work29k | |
10032 | @value{GDBP} myfoo | |
10033 | @end example | |
10034 | ||
10035 | @need 500 | |
10036 | Now you can use the @code{target} command: | |
10037 | ||
10038 | @example | |
10039 | target amd-eb /dev/ttya 9600 MYFOO | |
10040 | @c FIXME: test above 'target amd-eb' as spelled, with caps! caps are meant to | |
10041 | @c emphasize that this is the name as seen by DOS (since I think DOS is | |
10042 | @c single-minded about case of letters). ---doc@cygnus.com, 25feb91 | |
10043 | @end example | |
10044 | ||
10045 | @noindent | |
10046 | In this example, we've assumed your program is in a file called | |
10047 | @file{myfoo}. Note that the filename given as the last argument to | |
10048 | @code{target amd-eb} should be the name of the program as it appears to DOS. | |
10049 | In our example this is simply @code{MYFOO}, but in general it can include | |
10050 | a DOS path, and depending on your transfer mechanism may not resemble | |
10051 | the name on the Unix side. | |
10052 | ||
10053 | At this point, you can set any breakpoints you wish; when you are ready | |
10054 | to see your program run on the 29K board, use the @value{GDBN} command | |
10055 | @code{run}. | |
10056 | ||
10057 | To stop debugging the remote program, use the @value{GDBN} @code{detach} | |
10058 | command. | |
10059 | ||
10060 | To return control of the PC to its console, use @code{tip} or @code{cu} | |
10061 | once again, after your @value{GDBN} session has concluded, to attach to | |
10062 | @code{EBMON}. You can then type the command @code{q} to shut down | |
10063 | @code{EBMON}, returning control to the DOS command-line interpreter. | |
d4f3574e | 10064 | Type @kbd{CTTY con} to return command input to the main DOS console, |
104c1213 JM |
10065 | and type @kbd{~.} to leave @code{tip} or @code{cu}. |
10066 | ||
10067 | @node Remote Log | |
10068 | @subsubsection Remote log | |
10069 | @kindex eb.log | |
10070 | @cindex log file for EB29K | |
10071 | ||
10072 | The @code{target amd-eb} command creates a file @file{eb.log} in the | |
10073 | current working directory, to help debug problems with the connection. | |
10074 | @file{eb.log} records all the output from @code{EBMON}, including echoes | |
10075 | of the commands sent to it. Running @samp{tail -f} on this file in | |
10076 | another window often helps to understand trouble with @code{EBMON}, or | |
10077 | unexpected events on the PC side of the connection. | |
10078 | ||
10079 | @node ARM | |
10080 | @subsection ARM | |
10081 | ||
10082 | @table @code | |
10083 | ||
10084 | @kindex target rdi | |
10085 | @item target rdi @var{dev} | |
10086 | ARM Angel monitor, via RDI library interface to ADP protocol. You may | |
10087 | use this target to communicate with both boards running the Angel | |
10088 | monitor, or with the EmbeddedICE JTAG debug device. | |
10089 | ||
10090 | @kindex target rdp | |
10091 | @item target rdp @var{dev} | |
10092 | ARM Demon monitor. | |
10093 | ||
10094 | @end table | |
10095 | ||
10096 | @node H8/300 | |
10097 | @subsection Hitachi H8/300 | |
10098 | ||
10099 | @table @code | |
10100 | ||
d4f3574e | 10101 | @kindex target hms@r{, with H8/300} |
104c1213 JM |
10102 | @item target hms @var{dev} |
10103 | A Hitachi SH, H8/300, or H8/500 board, attached via serial line to your host. | |
10104 | Use special commands @code{device} and @code{speed} to control the serial | |
10105 | line and the communications speed used. | |
10106 | ||
d4f3574e | 10107 | @kindex target e7000@r{, with H8/300} |
104c1213 JM |
10108 | @item target e7000 @var{dev} |
10109 | E7000 emulator for Hitachi H8 and SH. | |
10110 | ||
d4f3574e SS |
10111 | @kindex target sh3@r{, with H8/300} |
10112 | @kindex target sh3e@r{, with H8/300} | |
104c1213 JM |
10113 | @item target sh3 @var{dev} |
10114 | @item target sh3e @var{dev} | |
10115 | Hitachi SH-3 and SH-3E target systems. | |
10116 | ||
10117 | @end table | |
10118 | ||
10119 | @cindex download to H8/300 or H8/500 | |
10120 | @cindex H8/300 or H8/500 download | |
10121 | @cindex download to Hitachi SH | |
10122 | @cindex Hitachi SH download | |
10123 | When you select remote debugging to a Hitachi SH, H8/300, or H8/500 | |
10124 | board, the @code{load} command downloads your program to the Hitachi | |
10125 | board and also opens it as the current executable target for | |
10126 | @value{GDBN} on your host (like the @code{file} command). | |
10127 | ||
10128 | @value{GDBN} needs to know these things to talk to your | |
10129 | Hitachi SH, H8/300, or H8/500: | |
10130 | ||
10131 | @enumerate | |
10132 | @item | |
10133 | that you want to use @samp{target hms}, the remote debugging interface | |
10134 | for Hitachi microprocessors, or @samp{target e7000}, the in-circuit | |
10135 | emulator for the Hitachi SH and the Hitachi 300H. (@samp{target hms} is | |
2df3850c | 10136 | the default when @value{GDBN} is configured specifically for the Hitachi SH, |
104c1213 JM |
10137 | H8/300, or H8/500.) |
10138 | ||
10139 | @item | |
10140 | what serial device connects your host to your Hitachi board (the first | |
10141 | serial device available on your host is the default). | |
10142 | ||
10143 | @item | |
10144 | what speed to use over the serial device. | |
10145 | @end enumerate | |
10146 | ||
10147 | @menu | |
10148 | * Hitachi Boards:: Connecting to Hitachi boards. | |
10149 | * Hitachi ICE:: Using the E7000 In-Circuit Emulator. | |
10150 | * Hitachi Special:: Special @value{GDBN} commands for Hitachi micros. | |
10151 | @end menu | |
10152 | ||
10153 | @node Hitachi Boards | |
10154 | @subsubsection Connecting to Hitachi boards | |
10155 | ||
10156 | @c only for Unix hosts | |
10157 | @kindex device | |
10158 | @cindex serial device, Hitachi micros | |
10159 | Use the special @code{@value{GDBP}} command @samp{device @var{port}} if you | |
10160 | need to explicitly set the serial device. The default @var{port} is the | |
10161 | first available port on your host. This is only necessary on Unix | |
10162 | hosts, where it is typically something like @file{/dev/ttya}. | |
10163 | ||
10164 | @kindex speed | |
10165 | @cindex serial line speed, Hitachi micros | |
10166 | @code{@value{GDBP}} has another special command to set the communications | |
10167 | speed: @samp{speed @var{bps}}. This command also is only used from Unix | |
2df3850c | 10168 | hosts; on DOS hosts, set the line speed as usual from outside @value{GDBN} with |
d4f3574e SS |
10169 | the DOS @code{mode} command (for instance, |
10170 | @w{@kbd{mode com2:9600,n,8,1,p}} for a 9600@dmn{bps} connection). | |
104c1213 JM |
10171 | |
10172 | The @samp{device} and @samp{speed} commands are available only when you | |
10173 | use a Unix host to debug your Hitachi microprocessor programs. If you | |
10174 | use a DOS host, | |
10175 | @value{GDBN} depends on an auxiliary terminate-and-stay-resident program | |
10176 | called @code{asynctsr} to communicate with the development board | |
10177 | through a PC serial port. You must also use the DOS @code{mode} command | |
10178 | to set up the serial port on the DOS side. | |
10179 | ||
10180 | The following sample session illustrates the steps needed to start a | |
10181 | program under @value{GDBN} control on an H8/300. The example uses a | |
10182 | sample H8/300 program called @file{t.x}. The procedure is the same for | |
10183 | the Hitachi SH and the H8/500. | |
10184 | ||
10185 | First hook up your development board. In this example, we use a | |
10186 | board attached to serial port @code{COM2}; if you use a different serial | |
10187 | port, substitute its name in the argument of the @code{mode} command. | |
10188 | When you call @code{asynctsr}, the auxiliary comms program used by the | |
d4f3574e | 10189 | debugger, you give it just the numeric part of the serial port's name; |
104c1213 JM |
10190 | for example, @samp{asyncstr 2} below runs @code{asyncstr} on |
10191 | @code{COM2}. | |
10192 | ||
10193 | @example | |
10194 | C:\H8300\TEST> asynctsr 2 | |
10195 | C:\H8300\TEST> mode com2:9600,n,8,1,p | |
10196 | ||
10197 | Resident portion of MODE loaded | |
10198 | ||
10199 | COM2: 9600, n, 8, 1, p | |
10200 | ||
10201 | @end example | |
10202 | ||
10203 | @quotation | |
10204 | @emph{Warning:} We have noticed a bug in PC-NFS that conflicts with | |
10205 | @code{asynctsr}. If you also run PC-NFS on your DOS host, you may need to | |
10206 | disable it, or even boot without it, to use @code{asynctsr} to control | |
10207 | your development board. | |
10208 | @end quotation | |
10209 | ||
d4f3574e | 10210 | @kindex target hms@r{, and serial protocol} |
104c1213 JM |
10211 | Now that serial communications are set up, and the development board is |
10212 | connected, you can start up @value{GDBN}. Call @code{@value{GDBP}} with | |
10213 | the name of your program as the argument. @code{@value{GDBP}} prompts | |
10214 | you, as usual, with the prompt @samp{(@value{GDBP})}. Use two special | |
10215 | commands to begin your debugging session: @samp{target hms} to specify | |
10216 | cross-debugging to the Hitachi board, and the @code{load} command to | |
10217 | download your program to the board. @code{load} displays the names of | |
10218 | the program's sections, and a @samp{*} for each 2K of data downloaded. | |
10219 | (If you want to refresh @value{GDBN} data on symbols or on the | |
10220 | executable file without downloading, use the @value{GDBN} commands | |
10221 | @code{file} or @code{symbol-file}. These commands, and @code{load} | |
10222 | itself, are described in @ref{Files,,Commands to specify files}.) | |
10223 | ||
10224 | @smallexample | |
10225 | (eg-C:\H8300\TEST) @value{GDBP} t.x | |
2df3850c | 10226 | @value{GDBN} is free software and you are welcome to distribute copies |
104c1213 JM |
10227 | of it under certain conditions; type "show copying" to see |
10228 | the conditions. | |
2df3850c | 10229 | There is absolutely no warranty for @value{GDBN}; type "show warranty" |
104c1213 | 10230 | for details. |
2df3850c JM |
10231 | @value{GDBN} @value{GDBVN}, Copyright 1992 Free Software Foundation, Inc... |
10232 | (@value{GDBP}) target hms | |
104c1213 | 10233 | Connected to remote H8/300 HMS system. |
2df3850c | 10234 | (@value{GDBP}) load t.x |
104c1213 JM |
10235 | .text : 0x8000 .. 0xabde *********** |
10236 | .data : 0xabde .. 0xad30 * | |
10237 | .stack : 0xf000 .. 0xf014 * | |
10238 | @end smallexample | |
10239 | ||
10240 | At this point, you're ready to run or debug your program. From here on, | |
10241 | you can use all the usual @value{GDBN} commands. The @code{break} command | |
10242 | sets breakpoints; the @code{run} command starts your program; | |
10243 | @code{print} or @code{x} display data; the @code{continue} command | |
10244 | resumes execution after stopping at a breakpoint. You can use the | |
10245 | @code{help} command at any time to find out more about @value{GDBN} commands. | |
10246 | ||
10247 | Remember, however, that @emph{operating system} facilities aren't | |
10248 | available on your development board; for example, if your program hangs, | |
10249 | you can't send an interrupt---but you can press the @sc{reset} switch! | |
10250 | ||
10251 | Use the @sc{reset} button on the development board | |
10252 | @itemize @bullet | |
10253 | @item | |
10254 | to interrupt your program (don't use @kbd{ctl-C} on the DOS host---it has | |
10255 | no way to pass an interrupt signal to the development board); and | |
10256 | ||
10257 | @item | |
10258 | to return to the @value{GDBN} command prompt after your program finishes | |
10259 | normally. The communications protocol provides no other way for @value{GDBN} | |
10260 | to detect program completion. | |
10261 | @end itemize | |
10262 | ||
10263 | In either case, @value{GDBN} sees the effect of a @sc{reset} on the | |
10264 | development board as a ``normal exit'' of your program. | |
10265 | ||
10266 | @node Hitachi ICE | |
10267 | @subsubsection Using the E7000 in-circuit emulator | |
10268 | ||
d4f3574e | 10269 | @kindex target e7000@r{, with Hitachi ICE} |
104c1213 JM |
10270 | You can use the E7000 in-circuit emulator to develop code for either the |
10271 | Hitachi SH or the H8/300H. Use one of these forms of the @samp{target | |
10272 | e7000} command to connect @value{GDBN} to your E7000: | |
10273 | ||
10274 | @table @code | |
10275 | @item target e7000 @var{port} @var{speed} | |
10276 | Use this form if your E7000 is connected to a serial port. The | |
10277 | @var{port} argument identifies what serial port to use (for example, | |
10278 | @samp{com2}). The third argument is the line speed in bits per second | |
10279 | (for example, @samp{9600}). | |
10280 | ||
10281 | @item target e7000 @var{hostname} | |
10282 | If your E7000 is installed as a host on a TCP/IP network, you can just | |
10283 | specify its hostname; @value{GDBN} uses @code{telnet} to connect. | |
10284 | @end table | |
10285 | ||
10286 | @node Hitachi Special | |
10287 | @subsubsection Special @value{GDBN} commands for Hitachi micros | |
10288 | ||
10289 | Some @value{GDBN} commands are available only for the H8/300: | |
10290 | ||
10291 | @table @code | |
10292 | ||
10293 | @kindex set machine | |
10294 | @kindex show machine | |
10295 | @item set machine h8300 | |
10296 | @itemx set machine h8300h | |
10297 | Condition @value{GDBN} for one of the two variants of the H8/300 | |
10298 | architecture with @samp{set machine}. You can use @samp{show machine} | |
10299 | to check which variant is currently in effect. | |
10300 | ||
10301 | @end table | |
10302 | ||
10303 | @node H8/500 | |
10304 | @subsection H8/500 | |
10305 | ||
10306 | @table @code | |
10307 | ||
10308 | @kindex set memory @var{mod} | |
10309 | @cindex memory models, H8/500 | |
10310 | @item set memory @var{mod} | |
10311 | @itemx show memory | |
10312 | Specify which H8/500 memory model (@var{mod}) you are using with | |
10313 | @samp{set memory}; check which memory model is in effect with @samp{show | |
10314 | memory}. The accepted values for @var{mod} are @code{small}, | |
10315 | @code{big}, @code{medium}, and @code{compact}. | |
10316 | ||
10317 | @end table | |
10318 | ||
10319 | @node i960 | |
10320 | @subsection Intel i960 | |
10321 | ||
10322 | @table @code | |
10323 | ||
10324 | @kindex target mon960 | |
10325 | @item target mon960 @var{dev} | |
10326 | MON960 monitor for Intel i960. | |
10327 | ||
10328 | @item target nindy @var{devicename} | |
10329 | An Intel 960 board controlled by a Nindy Monitor. @var{devicename} is | |
10330 | the name of the serial device to use for the connection, e.g. | |
10331 | @file{/dev/ttya}. | |
10332 | ||
10333 | @end table | |
10334 | ||
10335 | @cindex Nindy | |
10336 | @cindex i960 | |
10337 | @dfn{Nindy} is a ROM Monitor program for Intel 960 target systems. When | |
10338 | @value{GDBN} is configured to control a remote Intel 960 using Nindy, you can | |
10339 | tell @value{GDBN} how to connect to the 960 in several ways: | |
10340 | ||
10341 | @itemize @bullet | |
10342 | @item | |
10343 | Through command line options specifying serial port, version of the | |
10344 | Nindy protocol, and communications speed; | |
10345 | ||
10346 | @item | |
10347 | By responding to a prompt on startup; | |
10348 | ||
10349 | @item | |
10350 | By using the @code{target} command at any point during your @value{GDBN} | |
10351 | session. @xref{Target Commands, ,Commands for managing targets}. | |
10352 | ||
10353 | @kindex target nindy | |
10354 | @item target nindy @var{devicename} | |
10355 | An Intel 960 board controlled by a Nindy Monitor. @var{devicename} is | |
10356 | the name of the serial device to use for the connection, e.g. | |
10357 | @file{/dev/ttya}. | |
10358 | ||
10359 | @end itemize | |
10360 | ||
10361 | @cindex download to Nindy-960 | |
10362 | With the Nindy interface to an Intel 960 board, @code{load} | |
10363 | downloads @var{filename} to the 960 as well as adding its symbols in | |
10364 | @value{GDBN}. | |
10365 | ||
10366 | @menu | |
10367 | * Nindy Startup:: Startup with Nindy | |
10368 | * Nindy Options:: Options for Nindy | |
10369 | * Nindy Reset:: Nindy reset command | |
10370 | @end menu | |
10371 | ||
10372 | @node Nindy Startup | |
10373 | @subsubsection Startup with Nindy | |
10374 | ||
10375 | If you simply start @code{@value{GDBP}} without using any command-line | |
10376 | options, you are prompted for what serial port to use, @emph{before} you | |
10377 | reach the ordinary @value{GDBN} prompt: | |
10378 | ||
10379 | @example | |
10380 | Attach /dev/ttyNN -- specify NN, or "quit" to quit: | |
10381 | @end example | |
10382 | ||
10383 | @noindent | |
10384 | Respond to the prompt with whatever suffix (after @samp{/dev/tty}) | |
10385 | identifies the serial port you want to use. You can, if you choose, | |
10386 | simply start up with no Nindy connection by responding to the prompt | |
10387 | with an empty line. If you do this and later wish to attach to Nindy, | |
10388 | use @code{target} (@pxref{Target Commands, ,Commands for managing targets}). | |
10389 | ||
10390 | @node Nindy Options | |
10391 | @subsubsection Options for Nindy | |
10392 | ||
10393 | These are the startup options for beginning your @value{GDBN} session with a | |
10394 | Nindy-960 board attached: | |
10395 | ||
10396 | @table @code | |
10397 | @item -r @var{port} | |
10398 | Specify the serial port name of a serial interface to be used to connect | |
10399 | to the target system. This option is only available when @value{GDBN} is | |
10400 | configured for the Intel 960 target architecture. You may specify | |
10401 | @var{port} as any of: a full pathname (e.g. @samp{-r /dev/ttya}), a | |
10402 | device name in @file{/dev} (e.g. @samp{-r ttya}), or simply the unique | |
10403 | suffix for a specific @code{tty} (e.g. @samp{-r a}). | |
10404 | ||
10405 | @item -O | |
10406 | (An uppercase letter ``O'', not a zero.) Specify that @value{GDBN} should use | |
10407 | the ``old'' Nindy monitor protocol to connect to the target system. | |
10408 | This option is only available when @value{GDBN} is configured for the Intel 960 | |
10409 | target architecture. | |
10410 | ||
10411 | @quotation | |
10412 | @emph{Warning:} if you specify @samp{-O}, but are actually trying to | |
10413 | connect to a target system that expects the newer protocol, the connection | |
10414 | fails, appearing to be a speed mismatch. @value{GDBN} repeatedly | |
10415 | attempts to reconnect at several different line speeds. You can abort | |
10416 | this process with an interrupt. | |
10417 | @end quotation | |
10418 | ||
10419 | @item -brk | |
10420 | Specify that @value{GDBN} should first send a @code{BREAK} signal to the target | |
10421 | system, in an attempt to reset it, before connecting to a Nindy target. | |
10422 | ||
10423 | @quotation | |
10424 | @emph{Warning:} Many target systems do not have the hardware that this | |
10425 | requires; it only works with a few boards. | |
10426 | @end quotation | |
10427 | @end table | |
10428 | ||
10429 | The standard @samp{-b} option controls the line speed used on the serial | |
10430 | port. | |
10431 | ||
10432 | @c @group | |
10433 | @node Nindy Reset | |
10434 | @subsubsection Nindy reset command | |
10435 | ||
10436 | @table @code | |
10437 | @item reset | |
10438 | @kindex reset | |
10439 | For a Nindy target, this command sends a ``break'' to the remote target | |
10440 | system; this is only useful if the target has been equipped with a | |
10441 | circuit to perform a hard reset (or some other interesting action) when | |
10442 | a break is detected. | |
10443 | @end table | |
10444 | @c @end group | |
10445 | ||
10446 | @node M32R/D | |
10447 | @subsection Mitsubishi M32R/D | |
10448 | ||
10449 | @table @code | |
10450 | ||
10451 | @kindex target m32r | |
10452 | @item target m32r @var{dev} | |
10453 | Mitsubishi M32R/D ROM monitor. | |
10454 | ||
10455 | @end table | |
10456 | ||
10457 | @node M68K | |
10458 | @subsection M68k | |
10459 | ||
10460 | The Motorola m68k configuration includes ColdFire support, and | |
10461 | target command for the following ROM monitors. | |
10462 | ||
10463 | @table @code | |
10464 | ||
10465 | @kindex target abug | |
10466 | @item target abug @var{dev} | |
10467 | ABug ROM monitor for M68K. | |
10468 | ||
10469 | @kindex target cpu32bug | |
10470 | @item target cpu32bug @var{dev} | |
10471 | CPU32BUG monitor, running on a CPU32 (M68K) board. | |
10472 | ||
10473 | @kindex target dbug | |
10474 | @item target dbug @var{dev} | |
10475 | dBUG ROM monitor for Motorola ColdFire. | |
10476 | ||
10477 | @kindex target est | |
10478 | @item target est @var{dev} | |
10479 | EST-300 ICE monitor, running on a CPU32 (M68K) board. | |
10480 | ||
10481 | @kindex target rom68k | |
10482 | @item target rom68k @var{dev} | |
10483 | ROM 68K monitor, running on an M68K IDP board. | |
10484 | ||
10485 | @end table | |
10486 | ||
10487 | If @value{GDBN} is configured with @code{m68*-ericsson-*}, it will | |
10488 | instead have only a single special target command: | |
10489 | ||
10490 | @table @code | |
10491 | ||
10492 | @kindex target es1800 | |
10493 | @item target es1800 @var{dev} | |
10494 | ES-1800 emulator for M68K. | |
10495 | ||
10496 | @end table | |
10497 | ||
10498 | [context?] | |
10499 | ||
10500 | @table @code | |
10501 | ||
10502 | @kindex target rombug | |
10503 | @item target rombug @var{dev} | |
10504 | ROMBUG ROM monitor for OS/9000. | |
10505 | ||
10506 | @end table | |
10507 | ||
10508 | @node M88K | |
10509 | @subsection M88K | |
10510 | ||
10511 | @table @code | |
10512 | ||
10513 | @kindex target bug | |
10514 | @item target bug @var{dev} | |
10515 | BUG monitor, running on a MVME187 (m88k) board. | |
10516 | ||
10517 | @end table | |
10518 | ||
10519 | @node MIPS Embedded | |
10520 | @subsection MIPS Embedded | |
10521 | ||
10522 | @cindex MIPS boards | |
10523 | @value{GDBN} can use the MIPS remote debugging protocol to talk to a | |
10524 | MIPS board attached to a serial line. This is available when | |
10525 | you configure @value{GDBN} with @samp{--target=mips-idt-ecoff}. | |
10526 | ||
10527 | @need 1000 | |
10528 | Use these @value{GDBN} commands to specify the connection to your target board: | |
10529 | ||
10530 | @table @code | |
10531 | @item target mips @var{port} | |
10532 | @kindex target mips @var{port} | |
10533 | To run a program on the board, start up @code{@value{GDBP}} with the | |
10534 | name of your program as the argument. To connect to the board, use the | |
10535 | command @samp{target mips @var{port}}, where @var{port} is the name of | |
10536 | the serial port connected to the board. If the program has not already | |
10537 | been downloaded to the board, you may use the @code{load} command to | |
10538 | download it. You can then use all the usual @value{GDBN} commands. | |
10539 | ||
10540 | For example, this sequence connects to the target board through a serial | |
10541 | port, and loads and runs a program called @var{prog} through the | |
10542 | debugger: | |
10543 | ||
10544 | @example | |
10545 | host$ @value{GDBP} @var{prog} | |
2df3850c JM |
10546 | @value{GDBN} is free software and @dots{} |
10547 | (@value{GDBP}) target mips /dev/ttyb | |
10548 | (@value{GDBP}) load @var{prog} | |
10549 | (@value{GDBP}) run | |
104c1213 JM |
10550 | @end example |
10551 | ||
10552 | @item target mips @var{hostname}:@var{portnumber} | |
10553 | On some @value{GDBN} host configurations, you can specify a TCP | |
10554 | connection (for instance, to a serial line managed by a terminal | |
10555 | concentrator) instead of a serial port, using the syntax | |
10556 | @samp{@var{hostname}:@var{portnumber}}. | |
10557 | ||
10558 | @item target pmon @var{port} | |
10559 | @kindex target pmon @var{port} | |
10560 | PMON ROM monitor. | |
10561 | ||
10562 | @item target ddb @var{port} | |
10563 | @kindex target ddb @var{port} | |
10564 | NEC's DDB variant of PMON for Vr4300. | |
10565 | ||
10566 | @item target lsi @var{port} | |
10567 | @kindex target lsi @var{port} | |
10568 | LSI variant of PMON. | |
10569 | ||
10570 | @kindex target r3900 | |
10571 | @item target r3900 @var{dev} | |
10572 | Densan DVE-R3900 ROM monitor for Toshiba R3900 Mips. | |
10573 | ||
10574 | @kindex target array | |
10575 | @item target array @var{dev} | |
10576 | Array Tech LSI33K RAID controller board. | |
10577 | ||
10578 | @end table | |
10579 | ||
10580 | ||
10581 | @noindent | |
10582 | @value{GDBN} also supports these special commands for MIPS targets: | |
10583 | ||
10584 | @table @code | |
10585 | @item set processor @var{args} | |
10586 | @itemx show processor | |
10587 | @kindex set processor @var{args} | |
10588 | @kindex show processor | |
10589 | Use the @code{set processor} command to set the type of MIPS | |
10590 | processor when you want to access processor-type-specific registers. | |
10591 | For example, @code{set processor @var{r3041}} tells @value{GDBN} | |
10592 | to use the CPO registers appropriate for the 3041 chip. | |
10593 | Use the @code{show processor} command to see what MIPS processor @value{GDBN} | |
10594 | is using. Use the @code{info reg} command to see what registers | |
10595 | @value{GDBN} is using. | |
10596 | ||
10597 | @item set mipsfpu double | |
10598 | @itemx set mipsfpu single | |
10599 | @itemx set mipsfpu none | |
10600 | @itemx show mipsfpu | |
10601 | @kindex set mipsfpu | |
10602 | @kindex show mipsfpu | |
10603 | @cindex MIPS remote floating point | |
10604 | @cindex floating point, MIPS remote | |
10605 | If your target board does not support the MIPS floating point | |
10606 | coprocessor, you should use the command @samp{set mipsfpu none} (if you | |
10607 | need this, you may wish to put the command in your @value{GDBINIT} | |
10608 | file). This tells @value{GDBN} how to find the return value of | |
10609 | functions which return floating point values. It also allows | |
10610 | @value{GDBN} to avoid saving the floating point registers when calling | |
10611 | functions on the board. If you are using a floating point coprocessor | |
10612 | with only single precision floating point support, as on the @sc{r4650} | |
10613 | processor, use the command @samp{set mipsfpu single}. The default | |
10614 | double precision floating point coprocessor may be selected using | |
10615 | @samp{set mipsfpu double}. | |
10616 | ||
10617 | In previous versions the only choices were double precision or no | |
10618 | floating point, so @samp{set mipsfpu on} will select double precision | |
10619 | and @samp{set mipsfpu off} will select no floating point. | |
10620 | ||
10621 | As usual, you can inquire about the @code{mipsfpu} variable with | |
10622 | @samp{show mipsfpu}. | |
10623 | ||
10624 | @item set remotedebug @var{n} | |
10625 | @itemx show remotedebug | |
d4f3574e SS |
10626 | @kindex set remotedebug@r{, MIPS protocol} |
10627 | @kindex show remotedebug@r{, MIPS protocol} | |
104c1213 JM |
10628 | @cindex @code{remotedebug}, MIPS protocol |
10629 | @cindex MIPS @code{remotedebug} protocol | |
10630 | @c FIXME! For this to be useful, you must know something about the MIPS | |
10631 | @c FIXME...protocol. Where is it described? | |
10632 | You can see some debugging information about communications with the board | |
10633 | by setting the @code{remotedebug} variable. If you set it to @code{1} using | |
10634 | @samp{set remotedebug 1}, every packet is displayed. If you set it | |
10635 | to @code{2}, every character is displayed. You can check the current value | |
10636 | at any time with the command @samp{show remotedebug}. | |
10637 | ||
10638 | @item set timeout @var{seconds} | |
10639 | @itemx set retransmit-timeout @var{seconds} | |
10640 | @itemx show timeout | |
10641 | @itemx show retransmit-timeout | |
10642 | @cindex @code{timeout}, MIPS protocol | |
10643 | @cindex @code{retransmit-timeout}, MIPS protocol | |
10644 | @kindex set timeout | |
10645 | @kindex show timeout | |
10646 | @kindex set retransmit-timeout | |
10647 | @kindex show retransmit-timeout | |
10648 | You can control the timeout used while waiting for a packet, in the MIPS | |
10649 | remote protocol, with the @code{set timeout @var{seconds}} command. The | |
10650 | default is 5 seconds. Similarly, you can control the timeout used while | |
10651 | waiting for an acknowledgement of a packet with the @code{set | |
10652 | retransmit-timeout @var{seconds}} command. The default is 3 seconds. | |
10653 | You can inspect both values with @code{show timeout} and @code{show | |
10654 | retransmit-timeout}. (These commands are @emph{only} available when | |
10655 | @value{GDBN} is configured for @samp{--target=mips-idt-ecoff}.) | |
10656 | ||
10657 | The timeout set by @code{set timeout} does not apply when @value{GDBN} | |
10658 | is waiting for your program to stop. In that case, @value{GDBN} waits | |
10659 | forever because it has no way of knowing how long the program is going | |
10660 | to run before stopping. | |
10661 | @end table | |
10662 | ||
10663 | @node PowerPC | |
10664 | @subsection PowerPC | |
10665 | ||
10666 | @table @code | |
10667 | ||
10668 | @kindex target dink32 | |
10669 | @item target dink32 @var{dev} | |
10670 | DINK32 ROM monitor. | |
10671 | ||
10672 | @kindex target ppcbug | |
10673 | @item target ppcbug @var{dev} | |
10674 | @kindex target ppcbug1 | |
10675 | @item target ppcbug1 @var{dev} | |
10676 | PPCBUG ROM monitor for PowerPC. | |
10677 | ||
10678 | @kindex target sds | |
10679 | @item target sds @var{dev} | |
10680 | SDS monitor, running on a PowerPC board (such as Motorola's ADS). | |
10681 | ||
10682 | @end table | |
10683 | ||
10684 | @node PA | |
10685 | @subsection HP PA Embedded | |
10686 | ||
10687 | @table @code | |
10688 | ||
10689 | @kindex target op50n | |
10690 | @item target op50n @var{dev} | |
10691 | OP50N monitor, running on an OKI HPPA board. | |
10692 | ||
10693 | @kindex target w89k | |
10694 | @item target w89k @var{dev} | |
10695 | W89K monitor, running on a Winbond HPPA board. | |
10696 | ||
10697 | @end table | |
10698 | ||
10699 | @node SH | |
10700 | @subsection Hitachi SH | |
10701 | ||
10702 | @table @code | |
10703 | ||
d4f3574e | 10704 | @kindex target hms@r{, with Hitachi SH} |
104c1213 JM |
10705 | @item target hms @var{dev} |
10706 | A Hitachi SH board attached via serial line to your host. Use special | |
10707 | commands @code{device} and @code{speed} to control the serial line and | |
10708 | the communications speed used. | |
10709 | ||
d4f3574e | 10710 | @kindex target e7000@r{, with Hitachi SH} |
104c1213 JM |
10711 | @item target e7000 @var{dev} |
10712 | E7000 emulator for Hitachi SH. | |
10713 | ||
d4f3574e SS |
10714 | @kindex target sh3@r{, with SH} |
10715 | @kindex target sh3e@r{, with SH} | |
104c1213 JM |
10716 | @item target sh3 @var{dev} |
10717 | @item target sh3e @var{dev} | |
10718 | Hitachi SH-3 and SH-3E target systems. | |
10719 | ||
10720 | @end table | |
10721 | ||
10722 | @node Sparclet | |
10723 | @subsection Tsqware Sparclet | |
10724 | ||
10725 | @cindex Sparclet | |
10726 | ||
10727 | @value{GDBN} enables developers to debug tasks running on | |
10728 | Sparclet targets from a Unix host. | |
10729 | @value{GDBN} uses code that runs on | |
10730 | both the Unix host and on the Sparclet target. The program | |
d4f3574e | 10731 | @code{@value{GDBP}} is installed and executed on the Unix host. |
104c1213 JM |
10732 | |
10733 | @table @code | |
10734 | @item timeout @var{args} | |
10735 | @kindex remotetimeout | |
d4f3574e | 10736 | @value{GDBN} supports the option @code{remotetimeout}. |
104c1213 JM |
10737 | This option is set by the user, and @var{args} represents the number of |
10738 | seconds @value{GDBN} waits for responses. | |
10739 | @end table | |
10740 | ||
10741 | @kindex Compiling | |
d4f3574e SS |
10742 | When compiling for debugging, include the options @samp{-g} to get debug |
10743 | information and @samp{-Ttext} to relocate the program to where you wish to | |
10744 | load it on the target. You may also want to add the options @samp{-n} or | |
10745 | @samp{-N} in order to reduce the size of the sections. Example: | |
104c1213 JM |
10746 | |
10747 | @example | |
10748 | sparclet-aout-gcc prog.c -Ttext 0x12010000 -g -o prog -N | |
10749 | @end example | |
10750 | ||
d4f3574e | 10751 | You can use @code{objdump} to verify that the addresses are what you intended: |
104c1213 JM |
10752 | |
10753 | @example | |
10754 | sparclet-aout-objdump --headers --syms prog | |
10755 | @end example | |
10756 | ||
10757 | @kindex Running | |
10758 | Once you have set | |
10759 | your Unix execution search path to find @value{GDBN}, you are ready to | |
d4f3574e | 10760 | run @value{GDBN}. From your Unix host, run @code{@value{GDBP}} |
104c1213 JM |
10761 | (or @code{sparclet-aout-gdb}, depending on your installation). |
10762 | ||
10763 | @value{GDBN} comes up showing the prompt: | |
10764 | ||
10765 | @example | |
10766 | (gdbslet) | |
10767 | @end example | |
10768 | ||
10769 | @menu | |
10770 | * Sparclet File:: Setting the file to debug | |
10771 | * Sparclet Connection:: Connecting to Sparclet | |
10772 | * Sparclet Download:: Sparclet download | |
10773 | * Sparclet Execution:: Running and debugging | |
10774 | @end menu | |
10775 | ||
10776 | @node Sparclet File | |
10777 | @subsubsection Setting file to debug | |
10778 | ||
10779 | The @value{GDBN} command @code{file} lets you choose with program to debug. | |
10780 | ||
10781 | @example | |
10782 | (gdbslet) file prog | |
10783 | @end example | |
10784 | ||
10785 | @need 1000 | |
10786 | @value{GDBN} then attempts to read the symbol table of @file{prog}. | |
10787 | @value{GDBN} locates | |
10788 | the file by searching the directories listed in the command search | |
10789 | path. | |
10790 | If the file was compiled with debug information (option "-g"), source | |
10791 | files will be searched as well. | |
10792 | @value{GDBN} locates | |
10793 | the source files by searching the directories listed in the directory search | |
10794 | path (@pxref{Environment, ,Your program's environment}). | |
10795 | If it fails | |
10796 | to find a file, it displays a message such as: | |
10797 | ||
10798 | @example | |
10799 | prog: No such file or directory. | |
10800 | @end example | |
10801 | ||
10802 | When this happens, add the appropriate directories to the search paths with | |
10803 | the @value{GDBN} commands @code{path} and @code{dir}, and execute the | |
10804 | @code{target} command again. | |
10805 | ||
10806 | @node Sparclet Connection | |
10807 | @subsubsection Connecting to Sparclet | |
10808 | ||
10809 | The @value{GDBN} command @code{target} lets you connect to a Sparclet target. | |
10810 | To connect to a target on serial port ``@code{ttya}'', type: | |
10811 | ||
10812 | @example | |
10813 | (gdbslet) target sparclet /dev/ttya | |
10814 | Remote target sparclet connected to /dev/ttya | |
10815 | main () at ../prog.c:3 | |
10816 | @end example | |
10817 | ||
10818 | @need 750 | |
10819 | @value{GDBN} displays messages like these: | |
10820 | ||
d4f3574e | 10821 | @example |
104c1213 | 10822 | Connected to ttya. |
d4f3574e | 10823 | @end example |
104c1213 JM |
10824 | |
10825 | @node Sparclet Download | |
10826 | @subsubsection Sparclet download | |
10827 | ||
10828 | @cindex download to Sparclet | |
10829 | Once connected to the Sparclet target, | |
10830 | you can use the @value{GDBN} | |
10831 | @code{load} command to download the file from the host to the target. | |
10832 | The file name and load offset should be given as arguments to the @code{load} | |
10833 | command. | |
10834 | Since the file format is aout, the program must be loaded to the starting | |
d4f3574e | 10835 | address. You can use @code{objdump} to find out what this value is. The load |
104c1213 JM |
10836 | offset is an offset which is added to the VMA (virtual memory address) |
10837 | of each of the file's sections. | |
10838 | For instance, if the program | |
10839 | @file{prog} was linked to text address 0x1201000, with data at 0x12010160 | |
10840 | and bss at 0x12010170, in @value{GDBN}, type: | |
10841 | ||
10842 | @example | |
10843 | (gdbslet) load prog 0x12010000 | |
10844 | Loading section .text, size 0xdb0 vma 0x12010000 | |
10845 | @end example | |
10846 | ||
10847 | If the code is loaded at a different address then what the program was linked | |
10848 | to, you may need to use the @code{section} and @code{add-symbol-file} commands | |
10849 | to tell @value{GDBN} where to map the symbol table. | |
10850 | ||
10851 | @node Sparclet Execution | |
10852 | @subsubsection Running and debugging | |
10853 | ||
10854 | @cindex running and debugging Sparclet programs | |
10855 | You can now begin debugging the task using @value{GDBN}'s execution control | |
10856 | commands, @code{b}, @code{step}, @code{run}, etc. See the @value{GDBN} | |
10857 | manual for the list of commands. | |
10858 | ||
10859 | @example | |
10860 | (gdbslet) b main | |
10861 | Breakpoint 1 at 0x12010000: file prog.c, line 3. | |
10862 | (gdbslet) run | |
10863 | Starting program: prog | |
10864 | Breakpoint 1, main (argc=1, argv=0xeffff21c) at prog.c:3 | |
10865 | 3 char *symarg = 0; | |
10866 | (gdbslet) step | |
10867 | 4 char *execarg = "hello!"; | |
10868 | (gdbslet) | |
10869 | @end example | |
10870 | ||
10871 | @node Sparclite | |
10872 | @subsection Fujitsu Sparclite | |
10873 | ||
10874 | @table @code | |
10875 | ||
10876 | @kindex target sparclite | |
10877 | @item target sparclite @var{dev} | |
10878 | Fujitsu sparclite boards, used only for the purpose of loading. | |
10879 | You must use an additional command to debug the program. | |
10880 | For example: target remote @var{dev} using @value{GDBN} standard | |
10881 | remote protocol. | |
10882 | ||
10883 | @end table | |
10884 | ||
10885 | @node ST2000 | |
10886 | @subsection Tandem ST2000 | |
10887 | ||
2df3850c | 10888 | @value{GDBN} may be used with a Tandem ST2000 phone switch, running Tandem's |
104c1213 JM |
10889 | STDBUG protocol. |
10890 | ||
10891 | To connect your ST2000 to the host system, see the manufacturer's | |
10892 | manual. Once the ST2000 is physically attached, you can run: | |
10893 | ||
10894 | @example | |
10895 | target st2000 @var{dev} @var{speed} | |
10896 | @end example | |
10897 | ||
10898 | @noindent | |
10899 | to establish it as your debugging environment. @var{dev} is normally | |
10900 | the name of a serial device, such as @file{/dev/ttya}, connected to the | |
10901 | ST2000 via a serial line. You can instead specify @var{dev} as a TCP | |
10902 | connection (for example, to a serial line attached via a terminal | |
10903 | concentrator) using the syntax @code{@var{hostname}:@var{portnumber}}. | |
10904 | ||
10905 | The @code{load} and @code{attach} commands are @emph{not} defined for | |
10906 | this target; you must load your program into the ST2000 as you normally | |
10907 | would for standalone operation. @value{GDBN} reads debugging information | |
10908 | (such as symbols) from a separate, debugging version of the program | |
10909 | available on your host computer. | |
10910 | @c FIXME!! This is terribly vague; what little content is here is | |
10911 | @c basically hearsay. | |
10912 | ||
10913 | @cindex ST2000 auxiliary commands | |
10914 | These auxiliary @value{GDBN} commands are available to help you with the ST2000 | |
10915 | environment: | |
10916 | ||
10917 | @table @code | |
10918 | @item st2000 @var{command} | |
10919 | @kindex st2000 @var{cmd} | |
10920 | @cindex STDBUG commands (ST2000) | |
10921 | @cindex commands to STDBUG (ST2000) | |
10922 | Send a @var{command} to the STDBUG monitor. See the manufacturer's | |
10923 | manual for available commands. | |
10924 | ||
10925 | @item connect | |
10926 | @cindex connect (to STDBUG) | |
10927 | Connect the controlling terminal to the STDBUG command monitor. When | |
10928 | you are done interacting with STDBUG, typing either of two character | |
10929 | sequences gets you back to the @value{GDBN} command prompt: | |
10930 | @kbd{@key{RET}~.} (Return, followed by tilde and period) or | |
10931 | @kbd{@key{RET}~@key{C-d}} (Return, followed by tilde and control-D). | |
10932 | @end table | |
10933 | ||
10934 | @node Z8000 | |
10935 | @subsection Zilog Z8000 | |
10936 | ||
10937 | @cindex Z8000 | |
10938 | @cindex simulator, Z8000 | |
10939 | @cindex Zilog Z8000 simulator | |
10940 | ||
10941 | When configured for debugging Zilog Z8000 targets, @value{GDBN} includes | |
10942 | a Z8000 simulator. | |
10943 | ||
10944 | For the Z8000 family, @samp{target sim} simulates either the Z8002 (the | |
10945 | unsegmented variant of the Z8000 architecture) or the Z8001 (the | |
10946 | segmented variant). The simulator recognizes which architecture is | |
10947 | appropriate by inspecting the object code. | |
10948 | ||
10949 | @table @code | |
10950 | @item target sim @var{args} | |
10951 | @kindex sim | |
d4f3574e | 10952 | @kindex target sim@r{, with Z8000} |
104c1213 JM |
10953 | Debug programs on a simulated CPU. If the simulator supports setup |
10954 | options, specify them via @var{args}. | |
10955 | @end table | |
10956 | ||
10957 | @noindent | |
10958 | After specifying this target, you can debug programs for the simulated | |
10959 | CPU in the same style as programs for your host computer; use the | |
10960 | @code{file} command to load a new program image, the @code{run} command | |
10961 | to run your program, and so on. | |
10962 | ||
d4f3574e SS |
10963 | As well as making available all the usual machine registers |
10964 | (@pxref{Registers, ,Registers}), the Z8000 simulator provides three | |
10965 | additional items of information as specially named registers: | |
104c1213 JM |
10966 | |
10967 | @table @code | |
10968 | ||
10969 | @item cycles | |
10970 | Counts clock-ticks in the simulator. | |
10971 | ||
10972 | @item insts | |
10973 | Counts instructions run in the simulator. | |
10974 | ||
10975 | @item time | |
10976 | Execution time in 60ths of a second. | |
10977 | ||
10978 | @end table | |
10979 | ||
10980 | You can refer to these values in @value{GDBN} expressions with the usual | |
10981 | conventions; for example, @w{@samp{b fputc if $cycles>5000}} sets a | |
10982 | conditional breakpoint that suspends only after at least 5000 | |
10983 | simulated clock ticks. | |
10984 | ||
10985 | @node Architectures | |
10986 | @section Architectures | |
10987 | ||
10988 | This section describes characteristics of architectures that affect | |
2df3850c | 10989 | all uses of @value{GDBN} with the architecture, both native and cross. |
104c1213 JM |
10990 | |
10991 | @menu | |
10992 | * A29K:: | |
10993 | * Alpha:: | |
10994 | * MIPS:: | |
10995 | @end menu | |
10996 | ||
10997 | @node A29K | |
10998 | @subsection A29K | |
10999 | ||
11000 | @table @code | |
11001 | ||
11002 | @kindex set rstack_high_address | |
11003 | @cindex AMD 29K register stack | |
11004 | @cindex register stack, AMD29K | |
11005 | @item set rstack_high_address @var{address} | |
11006 | On AMD 29000 family processors, registers are saved in a separate | |
d4f3574e | 11007 | @dfn{register stack}. There is no way for @value{GDBN} to determine the |
104c1213 JM |
11008 | extent of this stack. Normally, @value{GDBN} just assumes that the |
11009 | stack is ``large enough''. This may result in @value{GDBN} referencing | |
11010 | memory locations that do not exist. If necessary, you can get around | |
11011 | this problem by specifying the ending address of the register stack with | |
11012 | the @code{set rstack_high_address} command. The argument should be an | |
11013 | address, which you probably want to precede with @samp{0x} to specify in | |
11014 | hexadecimal. | |
11015 | ||
11016 | @kindex show rstack_high_address | |
11017 | @item show rstack_high_address | |
11018 | Display the current limit of the register stack, on AMD 29000 family | |
11019 | processors. | |
11020 | ||
11021 | @end table | |
11022 | ||
11023 | @node Alpha | |
11024 | @subsection Alpha | |
11025 | ||
11026 | See the following section. | |
11027 | ||
11028 | @node MIPS | |
11029 | @subsection MIPS | |
11030 | ||
11031 | @cindex stack on Alpha | |
11032 | @cindex stack on MIPS | |
11033 | @cindex Alpha stack | |
11034 | @cindex MIPS stack | |
11035 | Alpha- and MIPS-based computers use an unusual stack frame, which | |
11036 | sometimes requires @value{GDBN} to search backward in the object code to | |
11037 | find the beginning of a function. | |
11038 | ||
11039 | @cindex response time, MIPS debugging | |
11040 | To improve response time (especially for embedded applications, where | |
11041 | @value{GDBN} may be restricted to a slow serial line for this search) | |
11042 | you may want to limit the size of this search, using one of these | |
11043 | commands: | |
11044 | ||
11045 | @table @code | |
11046 | @cindex @code{heuristic-fence-post} (Alpha,MIPS) | |
11047 | @item set heuristic-fence-post @var{limit} | |
11048 | Restrict @value{GDBN} to examining at most @var{limit} bytes in its | |
11049 | search for the beginning of a function. A value of @var{0} (the | |
11050 | default) means there is no limit. However, except for @var{0}, the | |
11051 | larger the limit the more bytes @code{heuristic-fence-post} must search | |
11052 | and therefore the longer it takes to run. | |
11053 | ||
11054 | @item show heuristic-fence-post | |
11055 | Display the current limit. | |
11056 | @end table | |
11057 | ||
11058 | @noindent | |
11059 | These commands are available @emph{only} when @value{GDBN} is configured | |
11060 | for debugging programs on Alpha or MIPS processors. | |
11061 | ||
11062 | ||
c906108c SS |
11063 | @node Controlling GDB |
11064 | @chapter Controlling @value{GDBN} | |
11065 | ||
53a5351d JM |
11066 | You can alter the way @value{GDBN} interacts with you by using the |
11067 | @code{set} command. For commands controlling how @value{GDBN} displays | |
d4f3574e | 11068 | data, see @ref{Print Settings, ,Print settings}. Other settings are |
53a5351d | 11069 | described here. |
c906108c SS |
11070 | |
11071 | @menu | |
11072 | * Prompt:: Prompt | |
11073 | * Editing:: Command editing | |
11074 | * History:: Command history | |
11075 | * Screen Size:: Screen size | |
11076 | * Numbers:: Numbers | |
11077 | * Messages/Warnings:: Optional warnings and messages | |
11078 | @end menu | |
11079 | ||
53a5351d | 11080 | @node Prompt |
c906108c SS |
11081 | @section Prompt |
11082 | ||
11083 | @cindex prompt | |
11084 | ||
11085 | @value{GDBN} indicates its readiness to read a command by printing a string | |
11086 | called the @dfn{prompt}. This string is normally @samp{(@value{GDBP})}. You | |
11087 | can change the prompt string with the @code{set prompt} command. For | |
11088 | instance, when debugging @value{GDBN} with @value{GDBN}, it is useful to change | |
11089 | the prompt in one of the @value{GDBN} sessions so that you can always tell | |
11090 | which one you are talking to. | |
11091 | ||
d4f3574e | 11092 | @emph{Note:} @code{set prompt} does not add a space for you after the |
c906108c SS |
11093 | prompt you set. This allows you to set a prompt which ends in a space |
11094 | or a prompt that does not. | |
11095 | ||
11096 | @table @code | |
11097 | @kindex set prompt | |
11098 | @item set prompt @var{newprompt} | |
11099 | Directs @value{GDBN} to use @var{newprompt} as its prompt string henceforth. | |
11100 | ||
11101 | @kindex show prompt | |
11102 | @item show prompt | |
11103 | Prints a line of the form: @samp{Gdb's prompt is: @var{your-prompt}} | |
11104 | @end table | |
11105 | ||
53a5351d | 11106 | @node Editing |
c906108c SS |
11107 | @section Command editing |
11108 | @cindex readline | |
11109 | @cindex command line editing | |
11110 | ||
11111 | @value{GDBN} reads its input commands via the @dfn{readline} interface. This | |
11112 | @sc{gnu} library provides consistent behavior for programs which provide a | |
11113 | command line interface to the user. Advantages are @sc{gnu} Emacs-style | |
11114 | or @dfn{vi}-style inline editing of commands, @code{csh}-like history | |
11115 | substitution, and a storage and recall of command history across | |
11116 | debugging sessions. | |
11117 | ||
11118 | You may control the behavior of command line editing in @value{GDBN} with the | |
11119 | command @code{set}. | |
11120 | ||
11121 | @table @code | |
11122 | @kindex set editing | |
11123 | @cindex editing | |
11124 | @item set editing | |
11125 | @itemx set editing on | |
11126 | Enable command line editing (enabled by default). | |
11127 | ||
11128 | @item set editing off | |
11129 | Disable command line editing. | |
11130 | ||
11131 | @kindex show editing | |
11132 | @item show editing | |
11133 | Show whether command line editing is enabled. | |
11134 | @end table | |
11135 | ||
53a5351d | 11136 | @node History |
c906108c SS |
11137 | @section Command history |
11138 | ||
11139 | @value{GDBN} can keep track of the commands you type during your | |
11140 | debugging sessions, so that you can be certain of precisely what | |
11141 | happened. Use these commands to manage the @value{GDBN} command | |
11142 | history facility. | |
11143 | ||
11144 | @table @code | |
11145 | @cindex history substitution | |
11146 | @cindex history file | |
11147 | @kindex set history filename | |
11148 | @kindex GDBHISTFILE | |
11149 | @item set history filename @var{fname} | |
11150 | Set the name of the @value{GDBN} command history file to @var{fname}. | |
11151 | This is the file where @value{GDBN} reads an initial command history | |
11152 | list, and where it writes the command history from this session when it | |
11153 | exits. You can access this list through history expansion or through | |
11154 | the history command editing characters listed below. This file defaults | |
11155 | to the value of the environment variable @code{GDBHISTFILE}, or to | |
d4f3574e SS |
11156 | @file{./.gdb_history} (@file{./_gdb_history} on MS-DOS) if this variable |
11157 | is not set. | |
c906108c SS |
11158 | |
11159 | @cindex history save | |
11160 | @kindex set history save | |
11161 | @item set history save | |
11162 | @itemx set history save on | |
11163 | Record command history in a file, whose name may be specified with the | |
11164 | @code{set history filename} command. By default, this option is disabled. | |
11165 | ||
11166 | @item set history save off | |
11167 | Stop recording command history in a file. | |
11168 | ||
11169 | @cindex history size | |
11170 | @kindex set history size | |
11171 | @item set history size @var{size} | |
11172 | Set the number of commands which @value{GDBN} keeps in its history list. | |
11173 | This defaults to the value of the environment variable | |
11174 | @code{HISTSIZE}, or to 256 if this variable is not set. | |
11175 | @end table | |
11176 | ||
11177 | @cindex history expansion | |
11178 | History expansion assigns special meaning to the character @kbd{!}. | |
11179 | @ifset have-readline-appendices | |
11180 | @xref{Event Designators}. | |
11181 | @end ifset | |
11182 | ||
11183 | Since @kbd{!} is also the logical not operator in C, history expansion | |
11184 | is off by default. If you decide to enable history expansion with the | |
11185 | @code{set history expansion on} command, you may sometimes need to | |
11186 | follow @kbd{!} (when it is used as logical not, in an expression) with | |
11187 | a space or a tab to prevent it from being expanded. The readline | |
11188 | history facilities do not attempt substitution on the strings | |
11189 | @kbd{!=} and @kbd{!(}, even when history expansion is enabled. | |
11190 | ||
11191 | The commands to control history expansion are: | |
11192 | ||
11193 | @table @code | |
11194 | @kindex set history expansion | |
11195 | @item set history expansion on | |
11196 | @itemx set history expansion | |
11197 | Enable history expansion. History expansion is off by default. | |
11198 | ||
11199 | @item set history expansion off | |
11200 | Disable history expansion. | |
11201 | ||
11202 | The readline code comes with more complete documentation of | |
11203 | editing and history expansion features. Users unfamiliar with @sc{gnu} Emacs | |
11204 | or @code{vi} may wish to read it. | |
11205 | @ifset have-readline-appendices | |
11206 | @xref{Command Line Editing}. | |
11207 | @end ifset | |
11208 | ||
11209 | @c @group | |
11210 | @kindex show history | |
11211 | @item show history | |
11212 | @itemx show history filename | |
11213 | @itemx show history save | |
11214 | @itemx show history size | |
11215 | @itemx show history expansion | |
11216 | These commands display the state of the @value{GDBN} history parameters. | |
11217 | @code{show history} by itself displays all four states. | |
11218 | @c @end group | |
11219 | @end table | |
11220 | ||
11221 | @table @code | |
11222 | @kindex show commands | |
11223 | @item show commands | |
11224 | Display the last ten commands in the command history. | |
11225 | ||
11226 | @item show commands @var{n} | |
11227 | Print ten commands centered on command number @var{n}. | |
11228 | ||
11229 | @item show commands + | |
11230 | Print ten commands just after the commands last printed. | |
11231 | @end table | |
11232 | ||
53a5351d | 11233 | @node Screen Size |
c906108c SS |
11234 | @section Screen size |
11235 | @cindex size of screen | |
11236 | @cindex pauses in output | |
11237 | ||
11238 | Certain commands to @value{GDBN} may produce large amounts of | |
11239 | information output to the screen. To help you read all of it, | |
11240 | @value{GDBN} pauses and asks you for input at the end of each page of | |
11241 | output. Type @key{RET} when you want to continue the output, or @kbd{q} | |
11242 | to discard the remaining output. Also, the screen width setting | |
11243 | determines when to wrap lines of output. Depending on what is being | |
11244 | printed, @value{GDBN} tries to break the line at a readable place, | |
11245 | rather than simply letting it overflow onto the following line. | |
11246 | ||
d4f3574e SS |
11247 | Normally @value{GDBN} knows the size of the screen from the terminal |
11248 | driver software. For example, on Unix @value{GDBN} uses the termcap data base | |
c906108c | 11249 | together with the value of the @code{TERM} environment variable and the |
d4f3574e | 11250 | @code{stty rows} and @code{stty cols} settings. If this is not correct, |
c906108c SS |
11251 | you can override it with the @code{set height} and @code{set |
11252 | width} commands: | |
11253 | ||
11254 | @table @code | |
11255 | @kindex set height | |
11256 | @kindex set width | |
11257 | @kindex show width | |
11258 | @kindex show height | |
11259 | @item set height @var{lpp} | |
11260 | @itemx show height | |
11261 | @itemx set width @var{cpl} | |
11262 | @itemx show width | |
11263 | These @code{set} commands specify a screen height of @var{lpp} lines and | |
11264 | a screen width of @var{cpl} characters. The associated @code{show} | |
11265 | commands display the current settings. | |
11266 | ||
11267 | If you specify a height of zero lines, @value{GDBN} does not pause during | |
11268 | output no matter how long the output is. This is useful if output is to a | |
11269 | file or to an editor buffer. | |
11270 | ||
11271 | Likewise, you can specify @samp{set width 0} to prevent @value{GDBN} | |
11272 | from wrapping its output. | |
11273 | @end table | |
11274 | ||
53a5351d | 11275 | @node Numbers |
c906108c SS |
11276 | @section Numbers |
11277 | @cindex number representation | |
11278 | @cindex entering numbers | |
11279 | ||
2df3850c JM |
11280 | You can always enter numbers in octal, decimal, or hexadecimal in |
11281 | @value{GDBN} by the usual conventions: octal numbers begin with | |
11282 | @samp{0}, decimal numbers end with @samp{.}, and hexadecimal numbers | |
11283 | begin with @samp{0x}. Numbers that begin with none of these are, by | |
11284 | default, entered in base 10; likewise, the default display for | |
11285 | numbers---when no particular format is specified---is base 10. You can | |
11286 | change the default base for both input and output with the @code{set | |
11287 | radix} command. | |
c906108c SS |
11288 | |
11289 | @table @code | |
11290 | @kindex set input-radix | |
11291 | @item set input-radix @var{base} | |
11292 | Set the default base for numeric input. Supported choices | |
11293 | for @var{base} are decimal 8, 10, or 16. @var{base} must itself be | |
11294 | specified either unambiguously or using the current default radix; for | |
11295 | example, any of | |
11296 | ||
11297 | @smallexample | |
11298 | set radix 012 | |
11299 | set radix 10. | |
11300 | set radix 0xa | |
11301 | @end smallexample | |
11302 | ||
11303 | @noindent | |
11304 | sets the base to decimal. On the other hand, @samp{set radix 10} | |
11305 | leaves the radix unchanged no matter what it was. | |
11306 | ||
11307 | @kindex set output-radix | |
11308 | @item set output-radix @var{base} | |
11309 | Set the default base for numeric display. Supported choices | |
11310 | for @var{base} are decimal 8, 10, or 16. @var{base} must itself be | |
11311 | specified either unambiguously or using the current default radix. | |
11312 | ||
11313 | @kindex show input-radix | |
11314 | @item show input-radix | |
11315 | Display the current default base for numeric input. | |
11316 | ||
11317 | @kindex show output-radix | |
11318 | @item show output-radix | |
11319 | Display the current default base for numeric display. | |
11320 | @end table | |
11321 | ||
53a5351d | 11322 | @node Messages/Warnings |
c906108c SS |
11323 | @section Optional warnings and messages |
11324 | ||
2df3850c JM |
11325 | By default, @value{GDBN} is silent about its inner workings. If you are |
11326 | running on a slow machine, you may want to use the @code{set verbose} | |
11327 | command. This makes @value{GDBN} tell you when it does a lengthy | |
11328 | internal operation, so you will not think it has crashed. | |
c906108c SS |
11329 | |
11330 | Currently, the messages controlled by @code{set verbose} are those | |
11331 | which announce that the symbol table for a source file is being read; | |
11332 | see @code{symbol-file} in @ref{Files, ,Commands to specify files}. | |
11333 | ||
11334 | @table @code | |
11335 | @kindex set verbose | |
11336 | @item set verbose on | |
11337 | Enables @value{GDBN} output of certain informational messages. | |
11338 | ||
11339 | @item set verbose off | |
11340 | Disables @value{GDBN} output of certain informational messages. | |
11341 | ||
11342 | @kindex show verbose | |
11343 | @item show verbose | |
11344 | Displays whether @code{set verbose} is on or off. | |
11345 | @end table | |
11346 | ||
2df3850c JM |
11347 | By default, if @value{GDBN} encounters bugs in the symbol table of an |
11348 | object file, it is silent; but if you are debugging a compiler, you may | |
11349 | find this information useful (@pxref{Symbol Errors, ,Errors reading | |
11350 | symbol files}). | |
c906108c SS |
11351 | |
11352 | @table @code | |
2df3850c | 11353 | |
c906108c SS |
11354 | @kindex set complaints |
11355 | @item set complaints @var{limit} | |
2df3850c JM |
11356 | Permits @value{GDBN} to output @var{limit} complaints about each type of |
11357 | unusual symbols before becoming silent about the problem. Set | |
11358 | @var{limit} to zero to suppress all complaints; set it to a large number | |
11359 | to prevent complaints from being suppressed. | |
c906108c SS |
11360 | |
11361 | @kindex show complaints | |
11362 | @item show complaints | |
11363 | Displays how many symbol complaints @value{GDBN} is permitted to produce. | |
2df3850c | 11364 | |
c906108c SS |
11365 | @end table |
11366 | ||
11367 | By default, @value{GDBN} is cautious, and asks what sometimes seems to be a | |
11368 | lot of stupid questions to confirm certain commands. For example, if | |
11369 | you try to run a program which is already running: | |
11370 | ||
11371 | @example | |
11372 | (@value{GDBP}) run | |
11373 | The program being debugged has been started already. | |
11374 | Start it from the beginning? (y or n) | |
11375 | @end example | |
11376 | ||
11377 | If you are willing to unflinchingly face the consequences of your own | |
11378 | commands, you can disable this ``feature'': | |
11379 | ||
11380 | @table @code | |
2df3850c | 11381 | |
c906108c SS |
11382 | @kindex set confirm |
11383 | @cindex flinching | |
11384 | @cindex confirmation | |
11385 | @cindex stupid questions | |
11386 | @item set confirm off | |
11387 | Disables confirmation requests. | |
11388 | ||
11389 | @item set confirm on | |
11390 | Enables confirmation requests (the default). | |
11391 | ||
11392 | @kindex show confirm | |
11393 | @item show confirm | |
11394 | Displays state of confirmation requests. | |
2df3850c | 11395 | |
c906108c SS |
11396 | @end table |
11397 | ||
53a5351d | 11398 | @node Sequences |
c906108c SS |
11399 | @chapter Canned Sequences of Commands |
11400 | ||
11401 | Aside from breakpoint commands (@pxref{Break Commands, ,Breakpoint | |
2df3850c JM |
11402 | command lists}), @value{GDBN} provides two ways to store sequences of |
11403 | commands for execution as a unit: user-defined commands and command | |
11404 | files. | |
c906108c SS |
11405 | |
11406 | @menu | |
11407 | * Define:: User-defined commands | |
11408 | * Hooks:: User-defined command hooks | |
11409 | * Command Files:: Command files | |
11410 | * Output:: Commands for controlled output | |
11411 | @end menu | |
11412 | ||
53a5351d | 11413 | @node Define |
c906108c SS |
11414 | @section User-defined commands |
11415 | ||
11416 | @cindex user-defined command | |
2df3850c JM |
11417 | A @dfn{user-defined command} is a sequence of @value{GDBN} commands to |
11418 | which you assign a new name as a command. This is done with the | |
11419 | @code{define} command. User commands may accept up to 10 arguments | |
11420 | separated by whitespace. Arguments are accessed within the user command | |
11421 | via @var{$arg0@dots{}$arg9}. A trivial example: | |
c906108c SS |
11422 | |
11423 | @smallexample | |
11424 | define adder | |
11425 | print $arg0 + $arg1 + $arg2 | |
11426 | @end smallexample | |
11427 | ||
d4f3574e SS |
11428 | @noindent |
11429 | To execute the command use: | |
c906108c SS |
11430 | |
11431 | @smallexample | |
11432 | adder 1 2 3 | |
11433 | @end smallexample | |
11434 | ||
d4f3574e SS |
11435 | @noindent |
11436 | This defines the command @code{adder}, which prints the sum of | |
c906108c SS |
11437 | its three arguments. Note the arguments are text substitutions, so they may |
11438 | reference variables, use complex expressions, or even perform inferior | |
11439 | functions calls. | |
11440 | ||
11441 | @table @code | |
2df3850c | 11442 | |
c906108c SS |
11443 | @kindex define |
11444 | @item define @var{commandname} | |
11445 | Define a command named @var{commandname}. If there is already a command | |
11446 | by that name, you are asked to confirm that you want to redefine it. | |
11447 | ||
11448 | The definition of the command is made up of other @value{GDBN} command lines, | |
11449 | which are given following the @code{define} command. The end of these | |
11450 | commands is marked by a line containing @code{end}. | |
11451 | ||
11452 | @kindex if | |
11453 | @kindex else | |
11454 | @item if | |
11455 | Takes a single argument, which is an expression to evaluate. | |
11456 | It is followed by a series of commands that are executed | |
11457 | only if the expression is true (nonzero). | |
11458 | There can then optionally be a line @code{else}, followed | |
11459 | by a series of commands that are only executed if the expression | |
11460 | was false. The end of the list is marked by a line containing @code{end}. | |
11461 | ||
11462 | @kindex while | |
11463 | @item while | |
11464 | The syntax is similar to @code{if}: the command takes a single argument, | |
11465 | which is an expression to evaluate, and must be followed by the commands to | |
11466 | execute, one per line, terminated by an @code{end}. | |
11467 | The commands are executed repeatedly as long as the expression | |
11468 | evaluates to true. | |
11469 | ||
11470 | @kindex document | |
11471 | @item document @var{commandname} | |
11472 | Document the user-defined command @var{commandname}, so that it can be | |
11473 | accessed by @code{help}. The command @var{commandname} must already be | |
11474 | defined. This command reads lines of documentation just as @code{define} | |
11475 | reads the lines of the command definition, ending with @code{end}. | |
11476 | After the @code{document} command is finished, @code{help} on command | |
11477 | @var{commandname} displays the documentation you have written. | |
11478 | ||
11479 | You may use the @code{document} command again to change the | |
11480 | documentation of a command. Redefining the command with @code{define} | |
11481 | does not change the documentation. | |
11482 | ||
11483 | @kindex help user-defined | |
11484 | @item help user-defined | |
11485 | List all user-defined commands, with the first line of the documentation | |
11486 | (if any) for each. | |
11487 | ||
11488 | @kindex show user | |
11489 | @item show user | |
11490 | @itemx show user @var{commandname} | |
2df3850c JM |
11491 | Display the @value{GDBN} commands used to define @var{commandname} (but |
11492 | not its documentation). If no @var{commandname} is given, display the | |
c906108c | 11493 | definitions for all user-defined commands. |
2df3850c | 11494 | |
c906108c SS |
11495 | @end table |
11496 | ||
11497 | When user-defined commands are executed, the | |
11498 | commands of the definition are not printed. An error in any command | |
11499 | stops execution of the user-defined command. | |
11500 | ||
11501 | If used interactively, commands that would ask for confirmation proceed | |
11502 | without asking when used inside a user-defined command. Many @value{GDBN} | |
11503 | commands that normally print messages to say what they are doing omit the | |
11504 | messages when used in a user-defined command. | |
11505 | ||
53a5351d | 11506 | @node Hooks |
c906108c | 11507 | @section User-defined command hooks |
d4f3574e SS |
11508 | @cindex command hooks |
11509 | @cindex hooks, for commands | |
c906108c SS |
11510 | |
11511 | You may define @emph{hooks}, which are a special kind of user-defined | |
11512 | command. Whenever you run the command @samp{foo}, if the user-defined | |
11513 | command @samp{hook-foo} exists, it is executed (with no arguments) | |
11514 | before that command. | |
11515 | ||
d4f3574e | 11516 | @kindex stop@r{, a pseudo-command} |
c906108c SS |
11517 | In addition, a pseudo-command, @samp{stop} exists. Defining |
11518 | (@samp{hook-stop}) makes the associated commands execute every time | |
11519 | execution stops in your program: before breakpoint commands are run, | |
11520 | displays are printed, or the stack frame is printed. | |
11521 | ||
c906108c SS |
11522 | For example, to ignore @code{SIGALRM} signals while |
11523 | single-stepping, but treat them normally during normal execution, | |
11524 | you could define: | |
11525 | ||
11526 | @example | |
11527 | define hook-stop | |
11528 | handle SIGALRM nopass | |
11529 | end | |
11530 | ||
11531 | define hook-run | |
11532 | handle SIGALRM pass | |
11533 | end | |
11534 | ||
11535 | define hook-continue | |
11536 | handle SIGLARM pass | |
11537 | end | |
11538 | @end example | |
c906108c SS |
11539 | |
11540 | You can define a hook for any single-word command in @value{GDBN}, but | |
11541 | not for command aliases; you should define a hook for the basic command | |
11542 | name, e.g. @code{backtrace} rather than @code{bt}. | |
11543 | @c FIXME! So how does Joe User discover whether a command is an alias | |
11544 | @c or not? | |
11545 | If an error occurs during the execution of your hook, execution of | |
11546 | @value{GDBN} commands stops and @value{GDBN} issues a prompt | |
11547 | (before the command that you actually typed had a chance to run). | |
11548 | ||
11549 | If you try to define a hook which does not match any known command, you | |
11550 | get a warning from the @code{define} command. | |
11551 | ||
53a5351d | 11552 | @node Command Files |
c906108c SS |
11553 | @section Command files |
11554 | ||
11555 | @cindex command files | |
11556 | A command file for @value{GDBN} is a file of lines that are @value{GDBN} | |
11557 | commands. Comments (lines starting with @kbd{#}) may also be included. | |
11558 | An empty line in a command file does nothing; it does not mean to repeat | |
11559 | the last command, as it would from the terminal. | |
11560 | ||
11561 | @cindex init file | |
11562 | @cindex @file{.gdbinit} | |
d4f3574e | 11563 | @cindex @file{gdb.ini} |
c906108c SS |
11564 | When you start @value{GDBN}, it automatically executes commands from its |
11565 | @dfn{init files}. These are files named @file{.gdbinit} on Unix, or | |
11566 | @file{gdb.ini} on DOS/Windows. @value{GDBN} reads the init file (if | |
d4f3574e | 11567 | any) in your home directory@footnote{On DOS/Windows systems, the home |
2df3850c JM |
11568 | directory is the one pointed to by the @code{HOME} environment |
11569 | variable.}, then processes command line options and operands, and then | |
11570 | reads the init file (if any) in the current working directory. This is | |
11571 | so the init file in your home directory can set options (such as | |
11572 | @code{set complaints}) which affect the processing of the command line | |
11573 | options and operands. The init files are not executed if you use the | |
11574 | @samp{-nx} option; @pxref{Mode Options, ,Choosing modes}. | |
c906108c | 11575 | |
c906108c SS |
11576 | @cindex init file name |
11577 | On some configurations of @value{GDBN}, the init file is known by a | |
11578 | different name (these are typically environments where a specialized | |
11579 | form of @value{GDBN} may need to coexist with other forms, hence a | |
11580 | different name for the specialized version's init file). These are the | |
11581 | environments with special init file names: | |
11582 | ||
11583 | @kindex .vxgdbinit | |
11584 | @itemize @bullet | |
11585 | @item | |
11586 | VxWorks (Wind River Systems real-time OS): @samp{.vxgdbinit} | |
11587 | ||
11588 | @kindex .os68gdbinit | |
11589 | @item | |
11590 | OS68K (Enea Data Systems real-time OS): @samp{.os68gdbinit} | |
11591 | ||
11592 | @kindex .esgdbinit | |
11593 | @item | |
11594 | ES-1800 (Ericsson Telecom AB M68000 emulator): @samp{.esgdbinit} | |
11595 | @end itemize | |
c906108c SS |
11596 | |
11597 | You can also request the execution of a command file with the | |
11598 | @code{source} command: | |
11599 | ||
11600 | @table @code | |
11601 | @kindex source | |
11602 | @item source @var{filename} | |
11603 | Execute the command file @var{filename}. | |
11604 | @end table | |
11605 | ||
11606 | The lines in a command file are executed sequentially. They are not | |
11607 | printed as they are executed. An error in any command terminates execution | |
11608 | of the command file. | |
11609 | ||
11610 | Commands that would ask for confirmation if used interactively proceed | |
11611 | without asking when used in a command file. Many @value{GDBN} commands that | |
11612 | normally print messages to say what they are doing omit the messages | |
11613 | when called from command files. | |
11614 | ||
53a5351d | 11615 | @node Output |
c906108c SS |
11616 | @section Commands for controlled output |
11617 | ||
11618 | During the execution of a command file or a user-defined command, normal | |
11619 | @value{GDBN} output is suppressed; the only output that appears is what is | |
11620 | explicitly printed by the commands in the definition. This section | |
11621 | describes three commands useful for generating exactly the output you | |
11622 | want. | |
11623 | ||
11624 | @table @code | |
11625 | @kindex echo | |
11626 | @item echo @var{text} | |
11627 | @c I do not consider backslash-space a standard C escape sequence | |
11628 | @c because it is not in ANSI. | |
11629 | Print @var{text}. Nonprinting characters can be included in | |
11630 | @var{text} using C escape sequences, such as @samp{\n} to print a | |
11631 | newline. @strong{No newline is printed unless you specify one.} | |
11632 | In addition to the standard C escape sequences, a backslash followed | |
11633 | by a space stands for a space. This is useful for displaying a | |
11634 | string with spaces at the beginning or the end, since leading and | |
11635 | trailing spaces are otherwise trimmed from all arguments. | |
11636 | To print @samp{@w{ }and foo =@w{ }}, use the command | |
11637 | @samp{echo \@w{ }and foo = \@w{ }}. | |
11638 | ||
11639 | A backslash at the end of @var{text} can be used, as in C, to continue | |
11640 | the command onto subsequent lines. For example, | |
11641 | ||
11642 | @example | |
11643 | echo This is some text\n\ | |
11644 | which is continued\n\ | |
11645 | onto several lines.\n | |
11646 | @end example | |
11647 | ||
11648 | produces the same output as | |
11649 | ||
11650 | @example | |
11651 | echo This is some text\n | |
11652 | echo which is continued\n | |
11653 | echo onto several lines.\n | |
11654 | @end example | |
11655 | ||
11656 | @kindex output | |
11657 | @item output @var{expression} | |
11658 | Print the value of @var{expression} and nothing but that value: no | |
11659 | newlines, no @samp{$@var{nn} = }. The value is not entered in the | |
11660 | value history either. @xref{Expressions, ,Expressions}, for more information | |
11661 | on expressions. | |
11662 | ||
11663 | @item output/@var{fmt} @var{expression} | |
11664 | Print the value of @var{expression} in format @var{fmt}. You can use | |
11665 | the same formats as for @code{print}. @xref{Output Formats,,Output | |
11666 | formats}, for more information. | |
11667 | ||
11668 | @kindex printf | |
11669 | @item printf @var{string}, @var{expressions}@dots{} | |
11670 | Print the values of the @var{expressions} under the control of | |
11671 | @var{string}. The @var{expressions} are separated by commas and may be | |
11672 | either numbers or pointers. Their values are printed as specified by | |
11673 | @var{string}, exactly as if your program were to execute the C | |
11674 | subroutine | |
d4f3574e SS |
11675 | @c FIXME: the above implies that at least all ANSI C formats are |
11676 | @c supported, but it isn't true: %E and %G don't work (or so it seems). | |
11677 | @c Either this is a bug, or the manual should document what formats are | |
11678 | @c supported. | |
c906108c SS |
11679 | |
11680 | @example | |
11681 | printf (@var{string}, @var{expressions}@dots{}); | |
11682 | @end example | |
11683 | ||
11684 | For example, you can print two values in hex like this: | |
11685 | ||
11686 | @smallexample | |
11687 | printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo | |
11688 | @end smallexample | |
11689 | ||
11690 | The only backslash-escape sequences that you can use in the format | |
11691 | string are the simple ones that consist of backslash followed by a | |
11692 | letter. | |
11693 | @end table | |
11694 | ||
53a5351d | 11695 | @node Emacs |
c906108c SS |
11696 | @chapter Using @value{GDBN} under @sc{gnu} Emacs |
11697 | ||
11698 | @cindex Emacs | |
11699 | @cindex @sc{gnu} Emacs | |
11700 | A special interface allows you to use @sc{gnu} Emacs to view (and | |
11701 | edit) the source files for the program you are debugging with | |
11702 | @value{GDBN}. | |
11703 | ||
11704 | To use this interface, use the command @kbd{M-x gdb} in Emacs. Give the | |
11705 | executable file you want to debug as an argument. This command starts | |
11706 | @value{GDBN} as a subprocess of Emacs, with input and output through a newly | |
11707 | created Emacs buffer. | |
53a5351d | 11708 | @c (Do not use the @code{-tui} option to run @value{GDBN} from Emacs.) |
c906108c SS |
11709 | |
11710 | Using @value{GDBN} under Emacs is just like using @value{GDBN} normally except for two | |
11711 | things: | |
11712 | ||
11713 | @itemize @bullet | |
11714 | @item | |
11715 | All ``terminal'' input and output goes through the Emacs buffer. | |
11716 | @end itemize | |
11717 | ||
11718 | This applies both to @value{GDBN} commands and their output, and to the input | |
11719 | and output done by the program you are debugging. | |
11720 | ||
11721 | This is useful because it means that you can copy the text of previous | |
11722 | commands and input them again; you can even use parts of the output | |
11723 | in this way. | |
11724 | ||
11725 | All the facilities of Emacs' Shell mode are available for interacting | |
11726 | with your program. In particular, you can send signals the usual | |
11727 | way---for example, @kbd{C-c C-c} for an interrupt, @kbd{C-c C-z} for a | |
11728 | stop. | |
11729 | ||
11730 | @itemize @bullet | |
11731 | @item | |
11732 | @value{GDBN} displays source code through Emacs. | |
11733 | @end itemize | |
11734 | ||
11735 | Each time @value{GDBN} displays a stack frame, Emacs automatically finds the | |
11736 | source file for that frame and puts an arrow (@samp{=>}) at the | |
11737 | left margin of the current line. Emacs uses a separate buffer for | |
11738 | source display, and splits the screen to show both your @value{GDBN} session | |
11739 | and the source. | |
11740 | ||
11741 | Explicit @value{GDBN} @code{list} or search commands still produce output as | |
11742 | usual, but you probably have no reason to use them from Emacs. | |
11743 | ||
11744 | @quotation | |
11745 | @emph{Warning:} If the directory where your program resides is not your | |
11746 | current directory, it can be easy to confuse Emacs about the location of | |
11747 | the source files, in which case the auxiliary display buffer does not | |
11748 | appear to show your source. @value{GDBN} can find programs by searching your | |
11749 | environment's @code{PATH} variable, so the @value{GDBN} input and output | |
11750 | session proceeds normally; but Emacs does not get enough information | |
11751 | back from @value{GDBN} to locate the source files in this situation. To | |
11752 | avoid this problem, either start @value{GDBN} mode from the directory where | |
11753 | your program resides, or specify an absolute file name when prompted for the | |
11754 | @kbd{M-x gdb} argument. | |
11755 | ||
11756 | A similar confusion can result if you use the @value{GDBN} @code{file} command to | |
11757 | switch to debugging a program in some other location, from an existing | |
11758 | @value{GDBN} buffer in Emacs. | |
11759 | @end quotation | |
11760 | ||
11761 | By default, @kbd{M-x gdb} calls the program called @file{gdb}. If | |
11762 | you need to call @value{GDBN} by a different name (for example, if you keep | |
11763 | several configurations around, with different names) you can set the | |
11764 | Emacs variable @code{gdb-command-name}; for example, | |
11765 | ||
11766 | @example | |
11767 | (setq gdb-command-name "mygdb") | |
11768 | @end example | |
11769 | ||
11770 | @noindent | |
d4f3574e | 11771 | (preceded by @kbd{M-:} or @kbd{ESC :}, or typed in the @code{*scratch*} buffer, or |
c906108c SS |
11772 | in your @file{.emacs} file) makes Emacs call the program named |
11773 | ``@code{mygdb}'' instead. | |
11774 | ||
11775 | In the @value{GDBN} I/O buffer, you can use these special Emacs commands in | |
11776 | addition to the standard Shell mode commands: | |
11777 | ||
11778 | @table @kbd | |
11779 | @item C-h m | |
11780 | Describe the features of Emacs' @value{GDBN} Mode. | |
11781 | ||
11782 | @item M-s | |
11783 | Execute to another source line, like the @value{GDBN} @code{step} command; also | |
11784 | update the display window to show the current file and location. | |
11785 | ||
11786 | @item M-n | |
11787 | Execute to next source line in this function, skipping all function | |
11788 | calls, like the @value{GDBN} @code{next} command. Then update the display window | |
11789 | to show the current file and location. | |
11790 | ||
11791 | @item M-i | |
11792 | Execute one instruction, like the @value{GDBN} @code{stepi} command; update | |
11793 | display window accordingly. | |
11794 | ||
11795 | @item M-x gdb-nexti | |
11796 | Execute to next instruction, using the @value{GDBN} @code{nexti} command; update | |
11797 | display window accordingly. | |
11798 | ||
11799 | @item C-c C-f | |
11800 | Execute until exit from the selected stack frame, like the @value{GDBN} | |
11801 | @code{finish} command. | |
11802 | ||
11803 | @item M-c | |
11804 | Continue execution of your program, like the @value{GDBN} @code{continue} | |
11805 | command. | |
11806 | ||
11807 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-p}. | |
11808 | ||
11809 | @item M-u | |
11810 | Go up the number of frames indicated by the numeric argument | |
11811 | (@pxref{Arguments, , Numeric Arguments, Emacs, The @sc{gnu} Emacs Manual}), | |
11812 | like the @value{GDBN} @code{up} command. | |
11813 | ||
11814 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-u}. | |
11815 | ||
11816 | @item M-d | |
11817 | Go down the number of frames indicated by the numeric argument, like the | |
11818 | @value{GDBN} @code{down} command. | |
11819 | ||
11820 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-d}. | |
11821 | ||
11822 | @item C-x & | |
11823 | Read the number where the cursor is positioned, and insert it at the end | |
11824 | of the @value{GDBN} I/O buffer. For example, if you wish to disassemble code | |
11825 | around an address that was displayed earlier, type @kbd{disassemble}; | |
11826 | then move the cursor to the address display, and pick up the | |
11827 | argument for @code{disassemble} by typing @kbd{C-x &}. | |
11828 | ||
11829 | You can customize this further by defining elements of the list | |
11830 | @code{gdb-print-command}; once it is defined, you can format or | |
11831 | otherwise process numbers picked up by @kbd{C-x &} before they are | |
11832 | inserted. A numeric argument to @kbd{C-x &} indicates that you | |
11833 | wish special formatting, and also acts as an index to pick an element of the | |
11834 | list. If the list element is a string, the number to be inserted is | |
11835 | formatted using the Emacs function @code{format}; otherwise the number | |
11836 | is passed as an argument to the corresponding list element. | |
11837 | @end table | |
11838 | ||
11839 | In any source file, the Emacs command @kbd{C-x SPC} (@code{gdb-break}) | |
11840 | tells @value{GDBN} to set a breakpoint on the source line point is on. | |
11841 | ||
11842 | If you accidentally delete the source-display buffer, an easy way to get | |
11843 | it back is to type the command @code{f} in the @value{GDBN} buffer, to | |
11844 | request a frame display; when you run under Emacs, this recreates | |
11845 | the source buffer if necessary to show you the context of the current | |
11846 | frame. | |
11847 | ||
11848 | The source files displayed in Emacs are in ordinary Emacs buffers | |
11849 | which are visiting the source files in the usual way. You can edit | |
11850 | the files with these buffers if you wish; but keep in mind that @value{GDBN} | |
11851 | communicates with Emacs in terms of line numbers. If you add or | |
11852 | delete lines from the text, the line numbers that @value{GDBN} knows cease | |
11853 | to correspond properly with the code. | |
11854 | ||
11855 | @c The following dropped because Epoch is nonstandard. Reactivate | |
11856 | @c if/when v19 does something similar. ---doc@cygnus.com 19dec1990 | |
11857 | @ignore | |
11858 | @kindex Emacs Epoch environment | |
11859 | @kindex Epoch | |
11860 | @kindex inspect | |
11861 | ||
11862 | Version 18 of @sc{gnu} Emacs has a built-in window system | |
11863 | called the @code{epoch} | |
11864 | environment. Users of this environment can use a new command, | |
11865 | @code{inspect} which performs identically to @code{print} except that | |
11866 | each value is printed in its own window. | |
11867 | @end ignore | |
c906108c SS |
11868 | |
11869 | @node GDB Bugs | |
c906108c SS |
11870 | @chapter Reporting Bugs in @value{GDBN} |
11871 | @cindex bugs in @value{GDBN} | |
11872 | @cindex reporting bugs in @value{GDBN} | |
11873 | ||
11874 | Your bug reports play an essential role in making @value{GDBN} reliable. | |
11875 | ||
11876 | Reporting a bug may help you by bringing a solution to your problem, or it | |
11877 | may not. But in any case the principal function of a bug report is to help | |
11878 | the entire community by making the next version of @value{GDBN} work better. Bug | |
11879 | reports are your contribution to the maintenance of @value{GDBN}. | |
11880 | ||
11881 | In order for a bug report to serve its purpose, you must include the | |
11882 | information that enables us to fix the bug. | |
11883 | ||
11884 | @menu | |
11885 | * Bug Criteria:: Have you found a bug? | |
11886 | * Bug Reporting:: How to report bugs | |
11887 | @end menu | |
11888 | ||
53a5351d | 11889 | @node Bug Criteria |
c906108c SS |
11890 | @section Have you found a bug? |
11891 | @cindex bug criteria | |
11892 | ||
11893 | If you are not sure whether you have found a bug, here are some guidelines: | |
11894 | ||
11895 | @itemize @bullet | |
11896 | @cindex fatal signal | |
11897 | @cindex debugger crash | |
11898 | @cindex crash of debugger | |
11899 | @item | |
11900 | If the debugger gets a fatal signal, for any input whatever, that is a | |
11901 | @value{GDBN} bug. Reliable debuggers never crash. | |
11902 | ||
11903 | @cindex error on valid input | |
11904 | @item | |
11905 | If @value{GDBN} produces an error message for valid input, that is a | |
11906 | bug. (Note that if you're cross debugging, the problem may also be | |
11907 | somewhere in the connection to the target.) | |
11908 | ||
11909 | @cindex invalid input | |
11910 | @item | |
11911 | If @value{GDBN} does not produce an error message for invalid input, | |
11912 | that is a bug. However, you should note that your idea of | |
11913 | ``invalid input'' might be our idea of ``an extension'' or ``support | |
11914 | for traditional practice''. | |
11915 | ||
11916 | @item | |
11917 | If you are an experienced user of debugging tools, your suggestions | |
11918 | for improvement of @value{GDBN} are welcome in any case. | |
11919 | @end itemize | |
11920 | ||
53a5351d | 11921 | @node Bug Reporting |
c906108c SS |
11922 | @section How to report bugs |
11923 | @cindex bug reports | |
11924 | @cindex @value{GDBN} bugs, reporting | |
11925 | ||
c906108c SS |
11926 | A number of companies and individuals offer support for @sc{gnu} products. |
11927 | If you obtained @value{GDBN} from a support organization, we recommend you | |
11928 | contact that organization first. | |
11929 | ||
11930 | You can find contact information for many support companies and | |
11931 | individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs | |
11932 | distribution. | |
11933 | @c should add a web page ref... | |
11934 | ||
11935 | In any event, we also recommend that you send bug reports for | |
11936 | @value{GDBN} to this addresses: | |
11937 | ||
11938 | @example | |
d4f3574e | 11939 | bug-gdb@@gnu.org |
c906108c SS |
11940 | @end example |
11941 | ||
11942 | @strong{Do not send bug reports to @samp{info-gdb}, or to | |
d4f3574e | 11943 | @samp{help-gdb}, or to any newsgroups.} Most users of @value{GDBN} do |
c906108c SS |
11944 | not want to receive bug reports. Those that do have arranged to receive |
11945 | @samp{bug-gdb}. | |
11946 | ||
11947 | The mailing list @samp{bug-gdb} has a newsgroup @samp{gnu.gdb.bug} which | |
11948 | serves as a repeater. The mailing list and the newsgroup carry exactly | |
11949 | the same messages. Often people think of posting bug reports to the | |
11950 | newsgroup instead of mailing them. This appears to work, but it has one | |
11951 | problem which can be crucial: a newsgroup posting often lacks a mail | |
11952 | path back to the sender. Thus, if we need to ask for more information, | |
11953 | we may be unable to reach you. For this reason, it is better to send | |
11954 | bug reports to the mailing list. | |
11955 | ||
11956 | As a last resort, send bug reports on paper to: | |
11957 | ||
11958 | @example | |
11959 | @sc{gnu} Debugger Bugs | |
11960 | Free Software Foundation Inc. | |
11961 | 59 Temple Place - Suite 330 | |
11962 | Boston, MA 02111-1307 | |
11963 | USA | |
11964 | @end example | |
c906108c SS |
11965 | |
11966 | The fundamental principle of reporting bugs usefully is this: | |
11967 | @strong{report all the facts}. If you are not sure whether to state a | |
11968 | fact or leave it out, state it! | |
11969 | ||
11970 | Often people omit facts because they think they know what causes the | |
11971 | problem and assume that some details do not matter. Thus, you might | |
11972 | assume that the name of the variable you use in an example does not matter. | |
11973 | Well, probably it does not, but one cannot be sure. Perhaps the bug is a | |
11974 | stray memory reference which happens to fetch from the location where that | |
11975 | name is stored in memory; perhaps, if the name were different, the contents | |
11976 | of that location would fool the debugger into doing the right thing despite | |
11977 | the bug. Play it safe and give a specific, complete example. That is the | |
11978 | easiest thing for you to do, and the most helpful. | |
11979 | ||
11980 | Keep in mind that the purpose of a bug report is to enable us to fix the | |
11981 | bug. It may be that the bug has been reported previously, but neither | |
11982 | you nor we can know that unless your bug report is complete and | |
11983 | self-contained. | |
11984 | ||
11985 | Sometimes people give a few sketchy facts and ask, ``Does this ring a | |
11986 | bell?'' Those bug reports are useless, and we urge everyone to | |
11987 | @emph{refuse to respond to them} except to chide the sender to report | |
11988 | bugs properly. | |
11989 | ||
11990 | To enable us to fix the bug, you should include all these things: | |
11991 | ||
11992 | @itemize @bullet | |
11993 | @item | |
11994 | The version of @value{GDBN}. @value{GDBN} announces it if you start | |
11995 | with no arguments; you can also print it at any time using @code{show | |
11996 | version}. | |
11997 | ||
11998 | Without this, we will not know whether there is any point in looking for | |
11999 | the bug in the current version of @value{GDBN}. | |
12000 | ||
12001 | @item | |
12002 | The type of machine you are using, and the operating system name and | |
12003 | version number. | |
12004 | ||
c906108c SS |
12005 | @item |
12006 | What compiler (and its version) was used to compile @value{GDBN}---e.g. | |
12007 | ``@value{GCC}--2.8.1''. | |
c906108c SS |
12008 | |
12009 | @item | |
12010 | What compiler (and its version) was used to compile the program you are | |
12011 | debugging---e.g. ``@value{GCC}--2.8.1'', or ``HP92453-01 A.10.32.03 HP | |
12012 | C Compiler''. For GCC, you can say @code{gcc --version} to get this | |
12013 | information; for other compilers, see the documentation for those | |
12014 | compilers. | |
12015 | ||
12016 | @item | |
12017 | The command arguments you gave the compiler to compile your example and | |
12018 | observe the bug. For example, did you use @samp{-O}? To guarantee | |
12019 | you will not omit something important, list them all. A copy of the | |
12020 | Makefile (or the output from make) is sufficient. | |
12021 | ||
12022 | If we were to try to guess the arguments, we would probably guess wrong | |
12023 | and then we might not encounter the bug. | |
12024 | ||
12025 | @item | |
12026 | A complete input script, and all necessary source files, that will | |
12027 | reproduce the bug. | |
12028 | ||
12029 | @item | |
12030 | A description of what behavior you observe that you believe is | |
12031 | incorrect. For example, ``It gets a fatal signal.'' | |
12032 | ||
12033 | Of course, if the bug is that @value{GDBN} gets a fatal signal, then we | |
12034 | will certainly notice it. But if the bug is incorrect output, we might | |
12035 | not notice unless it is glaringly wrong. You might as well not give us | |
12036 | a chance to make a mistake. | |
12037 | ||
12038 | Even if the problem you experience is a fatal signal, you should still | |
12039 | say so explicitly. Suppose something strange is going on, such as, your | |
12040 | copy of @value{GDBN} is out of synch, or you have encountered a bug in | |
12041 | the C library on your system. (This has happened!) Your copy might | |
12042 | crash and ours would not. If you told us to expect a crash, then when | |
12043 | ours fails to crash, we would know that the bug was not happening for | |
12044 | us. If you had not told us to expect a crash, then we would not be able | |
12045 | to draw any conclusion from our observations. | |
12046 | ||
c906108c SS |
12047 | @item |
12048 | If you wish to suggest changes to the @value{GDBN} source, send us context | |
12049 | diffs. If you even discuss something in the @value{GDBN} source, refer to | |
12050 | it by context, not by line number. | |
12051 | ||
12052 | The line numbers in our development sources will not match those in your | |
12053 | sources. Your line numbers would convey no useful information to us. | |
53a5351d | 12054 | |
c906108c SS |
12055 | @end itemize |
12056 | ||
12057 | Here are some things that are not necessary: | |
12058 | ||
12059 | @itemize @bullet | |
12060 | @item | |
12061 | A description of the envelope of the bug. | |
12062 | ||
12063 | Often people who encounter a bug spend a lot of time investigating | |
12064 | which changes to the input file will make the bug go away and which | |
12065 | changes will not affect it. | |
12066 | ||
12067 | This is often time consuming and not very useful, because the way we | |
12068 | will find the bug is by running a single example under the debugger | |
12069 | with breakpoints, not by pure deduction from a series of examples. | |
12070 | We recommend that you save your time for something else. | |
12071 | ||
12072 | Of course, if you can find a simpler example to report @emph{instead} | |
12073 | of the original one, that is a convenience for us. Errors in the | |
12074 | output will be easier to spot, running under the debugger will take | |
12075 | less time, and so on. | |
12076 | ||
12077 | However, simplification is not vital; if you do not want to do this, | |
12078 | report the bug anyway and send us the entire test case you used. | |
12079 | ||
12080 | @item | |
12081 | A patch for the bug. | |
12082 | ||
12083 | A patch for the bug does help us if it is a good one. But do not omit | |
12084 | the necessary information, such as the test case, on the assumption that | |
12085 | a patch is all we need. We might see problems with your patch and decide | |
12086 | to fix the problem another way, or we might not understand it at all. | |
12087 | ||
12088 | Sometimes with a program as complicated as @value{GDBN} it is very hard to | |
12089 | construct an example that will make the program follow a certain path | |
12090 | through the code. If you do not send us the example, we will not be able | |
12091 | to construct one, so we will not be able to verify that the bug is fixed. | |
12092 | ||
12093 | And if we cannot understand what bug you are trying to fix, or why your | |
12094 | patch should be an improvement, we will not install it. A test case will | |
12095 | help us to understand. | |
12096 | ||
12097 | @item | |
12098 | A guess about what the bug is or what it depends on. | |
12099 | ||
12100 | Such guesses are usually wrong. Even we cannot guess right about such | |
12101 | things without first using the debugger to find the facts. | |
12102 | @end itemize | |
12103 | ||
12104 | @c The readline documentation is distributed with the readline code | |
12105 | @c and consists of the two following files: | |
12106 | @c rluser.texinfo | |
7be570e7 | 12107 | @c inc-hist.texinfo |
c906108c SS |
12108 | @c Use -I with makeinfo to point to the appropriate directory, |
12109 | @c environment var TEXINPUTS with TeX. | |
12110 | @include rluser.texinfo | |
7be570e7 | 12111 | @include inc-hist.texinfo |
c906108c SS |
12112 | |
12113 | ||
c906108c | 12114 | @node Formatting Documentation |
c906108c SS |
12115 | @appendix Formatting Documentation |
12116 | ||
12117 | @cindex @value{GDBN} reference card | |
12118 | @cindex reference card | |
12119 | The @value{GDBN} 4 release includes an already-formatted reference card, ready | |
12120 | for printing with PostScript or Ghostscript, in the @file{gdb} | |
12121 | subdirectory of the main source directory@footnote{In | |
12122 | @file{gdb-@value{GDBVN}/gdb/refcard.ps} of the version @value{GDBVN} | |
12123 | release.}. If you can use PostScript or Ghostscript with your printer, | |
12124 | you can print the reference card immediately with @file{refcard.ps}. | |
12125 | ||
12126 | The release also includes the source for the reference card. You | |
12127 | can format it, using @TeX{}, by typing: | |
12128 | ||
12129 | @example | |
12130 | make refcard.dvi | |
12131 | @end example | |
12132 | ||
12133 | The @value{GDBN} reference card is designed to print in @dfn{landscape} | |
12134 | mode on US ``letter'' size paper; | |
12135 | that is, on a sheet 11 inches wide by 8.5 inches | |
12136 | high. You will need to specify this form of printing as an option to | |
12137 | your @sc{dvi} output program. | |
12138 | ||
12139 | @cindex documentation | |
12140 | ||
12141 | All the documentation for @value{GDBN} comes as part of the machine-readable | |
12142 | distribution. The documentation is written in Texinfo format, which is | |
12143 | a documentation system that uses a single source file to produce both | |
12144 | on-line information and a printed manual. You can use one of the Info | |
12145 | formatting commands to create the on-line version of the documentation | |
12146 | and @TeX{} (or @code{texi2roff}) to typeset the printed version. | |
12147 | ||
12148 | @value{GDBN} includes an already formatted copy of the on-line Info | |
12149 | version of this manual in the @file{gdb} subdirectory. The main Info | |
12150 | file is @file{gdb-@value{GDBVN}/gdb/gdb.info}, and it refers to | |
12151 | subordinate files matching @samp{gdb.info*} in the same directory. If | |
12152 | necessary, you can print out these files, or read them with any editor; | |
12153 | but they are easier to read using the @code{info} subsystem in @sc{gnu} | |
12154 | Emacs or the standalone @code{info} program, available as part of the | |
12155 | @sc{gnu} Texinfo distribution. | |
12156 | ||
12157 | If you want to format these Info files yourself, you need one of the | |
12158 | Info formatting programs, such as @code{texinfo-format-buffer} or | |
12159 | @code{makeinfo}. | |
12160 | ||
12161 | If you have @code{makeinfo} installed, and are in the top level | |
12162 | @value{GDBN} source directory (@file{gdb-@value{GDBVN}}, in the case of | |
12163 | version @value{GDBVN}), you can make the Info file by typing: | |
12164 | ||
12165 | @example | |
12166 | cd gdb | |
12167 | make gdb.info | |
12168 | @end example | |
12169 | ||
12170 | If you want to typeset and print copies of this manual, you need @TeX{}, | |
12171 | a program to print its @sc{dvi} output files, and @file{texinfo.tex}, the | |
12172 | Texinfo definitions file. | |
12173 | ||
12174 | @TeX{} is a typesetting program; it does not print files directly, but | |
12175 | produces output files called @sc{dvi} files. To print a typeset | |
12176 | document, you need a program to print @sc{dvi} files. If your system | |
12177 | has @TeX{} installed, chances are it has such a program. The precise | |
12178 | command to use depends on your system; @kbd{lpr -d} is common; another | |
12179 | (for PostScript devices) is @kbd{dvips}. The @sc{dvi} print command may | |
12180 | require a file name without any extension or a @samp{.dvi} extension. | |
12181 | ||
12182 | @TeX{} also requires a macro definitions file called | |
12183 | @file{texinfo.tex}. This file tells @TeX{} how to typeset a document | |
12184 | written in Texinfo format. On its own, @TeX{} cannot either read or | |
12185 | typeset a Texinfo file. @file{texinfo.tex} is distributed with GDB | |
12186 | and is located in the @file{gdb-@var{version-number}/texinfo} | |
12187 | directory. | |
12188 | ||
12189 | If you have @TeX{} and a @sc{dvi} printer program installed, you can | |
12190 | typeset and print this manual. First switch to the the @file{gdb} | |
12191 | subdirectory of the main source directory (for example, to | |
12192 | @file{gdb-@value{GDBVN}/gdb}) and type: | |
12193 | ||
12194 | @example | |
12195 | make gdb.dvi | |
12196 | @end example | |
12197 | ||
12198 | Then give @file{gdb.dvi} to your @sc{dvi} printing program. | |
c906108c | 12199 | |
53a5351d | 12200 | @node Installing GDB |
c906108c SS |
12201 | @appendix Installing @value{GDBN} |
12202 | @cindex configuring @value{GDBN} | |
12203 | @cindex installation | |
12204 | ||
c906108c SS |
12205 | @value{GDBN} comes with a @code{configure} script that automates the process |
12206 | of preparing @value{GDBN} for installation; you can then use @code{make} to | |
12207 | build the @code{gdb} program. | |
12208 | @iftex | |
12209 | @c irrelevant in info file; it's as current as the code it lives with. | |
12210 | @footnote{If you have a more recent version of @value{GDBN} than @value{GDBVN}, | |
12211 | look at the @file{README} file in the sources; we may have improved the | |
12212 | installation procedures since publishing this manual.} | |
12213 | @end iftex | |
12214 | ||
12215 | The @value{GDBN} distribution includes all the source code you need for | |
12216 | @value{GDBN} in a single directory, whose name is usually composed by | |
12217 | appending the version number to @samp{gdb}. | |
12218 | ||
12219 | For example, the @value{GDBN} version @value{GDBVN} distribution is in the | |
12220 | @file{gdb-@value{GDBVN}} directory. That directory contains: | |
12221 | ||
12222 | @table @code | |
12223 | @item gdb-@value{GDBVN}/configure @r{(and supporting files)} | |
12224 | script for configuring @value{GDBN} and all its supporting libraries | |
12225 | ||
12226 | @item gdb-@value{GDBVN}/gdb | |
12227 | the source specific to @value{GDBN} itself | |
12228 | ||
12229 | @item gdb-@value{GDBVN}/bfd | |
12230 | source for the Binary File Descriptor library | |
12231 | ||
12232 | @item gdb-@value{GDBVN}/include | |
12233 | @sc{gnu} include files | |
12234 | ||
12235 | @item gdb-@value{GDBVN}/libiberty | |
12236 | source for the @samp{-liberty} free software library | |
12237 | ||
12238 | @item gdb-@value{GDBVN}/opcodes | |
12239 | source for the library of opcode tables and disassemblers | |
12240 | ||
12241 | @item gdb-@value{GDBVN}/readline | |
12242 | source for the @sc{gnu} command-line interface | |
12243 | ||
12244 | @item gdb-@value{GDBVN}/glob | |
12245 | source for the @sc{gnu} filename pattern-matching subroutine | |
12246 | ||
12247 | @item gdb-@value{GDBVN}/mmalloc | |
12248 | source for the @sc{gnu} memory-mapped malloc package | |
12249 | @end table | |
12250 | ||
12251 | The simplest way to configure and build @value{GDBN} is to run @code{configure} | |
12252 | from the @file{gdb-@var{version-number}} source directory, which in | |
12253 | this example is the @file{gdb-@value{GDBVN}} directory. | |
12254 | ||
12255 | First switch to the @file{gdb-@var{version-number}} source directory | |
12256 | if you are not already in it; then run @code{configure}. Pass the | |
12257 | identifier for the platform on which @value{GDBN} will run as an | |
12258 | argument. | |
12259 | ||
12260 | For example: | |
12261 | ||
12262 | @example | |
12263 | cd gdb-@value{GDBVN} | |
12264 | ./configure @var{host} | |
12265 | make | |
12266 | @end example | |
12267 | ||
12268 | @noindent | |
12269 | where @var{host} is an identifier such as @samp{sun4} or | |
12270 | @samp{decstation}, that identifies the platform where @value{GDBN} will run. | |
12271 | (You can often leave off @var{host}; @code{configure} tries to guess the | |
12272 | correct value by examining your system.) | |
12273 | ||
12274 | Running @samp{configure @var{host}} and then running @code{make} builds the | |
12275 | @file{bfd}, @file{readline}, @file{mmalloc}, and @file{libiberty} | |
12276 | libraries, then @code{gdb} itself. The configured source files, and the | |
12277 | binaries, are left in the corresponding source directories. | |
12278 | ||
12279 | @need 750 | |
12280 | @code{configure} is a Bourne-shell (@code{/bin/sh}) script; if your | |
12281 | system does not recognize this automatically when you run a different | |
12282 | shell, you may need to run @code{sh} on it explicitly: | |
12283 | ||
12284 | @example | |
12285 | sh configure @var{host} | |
12286 | @end example | |
12287 | ||
12288 | If you run @code{configure} from a directory that contains source | |
12289 | directories for multiple libraries or programs, such as the | |
12290 | @file{gdb-@value{GDBVN}} source directory for version @value{GDBVN}, @code{configure} | |
12291 | creates configuration files for every directory level underneath (unless | |
12292 | you tell it not to, with the @samp{--norecursion} option). | |
12293 | ||
12294 | You can run the @code{configure} script from any of the | |
12295 | subordinate directories in the @value{GDBN} distribution if you only want to | |
12296 | configure that subdirectory, but be sure to specify a path to it. | |
12297 | ||
12298 | For example, with version @value{GDBVN}, type the following to configure only | |
12299 | the @code{bfd} subdirectory: | |
12300 | ||
12301 | @example | |
12302 | @group | |
12303 | cd gdb-@value{GDBVN}/bfd | |
12304 | ../configure @var{host} | |
12305 | @end group | |
12306 | @end example | |
12307 | ||
12308 | You can install @code{@value{GDBP}} anywhere; it has no hardwired paths. | |
12309 | However, you should make sure that the shell on your path (named by | |
12310 | the @samp{SHELL} environment variable) is publicly readable. Remember | |
12311 | that @value{GDBN} uses the shell to start your program---some systems refuse to | |
12312 | let @value{GDBN} debug child processes whose programs are not readable. | |
12313 | ||
12314 | @menu | |
12315 | * Separate Objdir:: Compiling @value{GDBN} in another directory | |
12316 | * Config Names:: Specifying names for hosts and targets | |
12317 | * Configure Options:: Summary of options for configure | |
12318 | @end menu | |
12319 | ||
53a5351d | 12320 | @node Separate Objdir |
c906108c SS |
12321 | @section Compiling @value{GDBN} in another directory |
12322 | ||
12323 | If you want to run @value{GDBN} versions for several host or target machines, | |
12324 | you need a different @code{gdb} compiled for each combination of | |
12325 | host and target. @code{configure} is designed to make this easy by | |
12326 | allowing you to generate each configuration in a separate subdirectory, | |
12327 | rather than in the source directory. If your @code{make} program | |
12328 | handles the @samp{VPATH} feature (@sc{gnu} @code{make} does), running | |
12329 | @code{make} in each of these directories builds the @code{gdb} | |
12330 | program specified there. | |
12331 | ||
12332 | To build @code{gdb} in a separate directory, run @code{configure} | |
12333 | with the @samp{--srcdir} option to specify where to find the source. | |
12334 | (You also need to specify a path to find @code{configure} | |
12335 | itself from your working directory. If the path to @code{configure} | |
12336 | would be the same as the argument to @samp{--srcdir}, you can leave out | |
12337 | the @samp{--srcdir} option; it is assumed.) | |
12338 | ||
12339 | For example, with version @value{GDBVN}, you can build @value{GDBN} in a | |
12340 | separate directory for a Sun 4 like this: | |
12341 | ||
12342 | @example | |
12343 | @group | |
12344 | cd gdb-@value{GDBVN} | |
12345 | mkdir ../gdb-sun4 | |
12346 | cd ../gdb-sun4 | |
12347 | ../gdb-@value{GDBVN}/configure sun4 | |
12348 | make | |
12349 | @end group | |
12350 | @end example | |
12351 | ||
12352 | When @code{configure} builds a configuration using a remote source | |
12353 | directory, it creates a tree for the binaries with the same structure | |
12354 | (and using the same names) as the tree under the source directory. In | |
12355 | the example, you'd find the Sun 4 library @file{libiberty.a} in the | |
12356 | directory @file{gdb-sun4/libiberty}, and @value{GDBN} itself in | |
12357 | @file{gdb-sun4/gdb}. | |
12358 | ||
12359 | One popular reason to build several @value{GDBN} configurations in separate | |
12360 | directories is to configure @value{GDBN} for cross-compiling (where | |
12361 | @value{GDBN} runs on one machine---the @dfn{host}---while debugging | |
12362 | programs that run on another machine---the @dfn{target}). | |
12363 | You specify a cross-debugging target by | |
12364 | giving the @samp{--target=@var{target}} option to @code{configure}. | |
12365 | ||
12366 | When you run @code{make} to build a program or library, you must run | |
12367 | it in a configured directory---whatever directory you were in when you | |
12368 | called @code{configure} (or one of its subdirectories). | |
12369 | ||
12370 | The @code{Makefile} that @code{configure} generates in each source | |
12371 | directory also runs recursively. If you type @code{make} in a source | |
12372 | directory such as @file{gdb-@value{GDBVN}} (or in a separate configured | |
12373 | directory configured with @samp{--srcdir=@var{dirname}/gdb-@value{GDBVN}}), you | |
12374 | will build all the required libraries, and then build GDB. | |
12375 | ||
12376 | When you have multiple hosts or targets configured in separate | |
12377 | directories, you can run @code{make} on them in parallel (for example, | |
12378 | if they are NFS-mounted on each of the hosts); they will not interfere | |
12379 | with each other. | |
12380 | ||
53a5351d | 12381 | @node Config Names |
c906108c SS |
12382 | @section Specifying names for hosts and targets |
12383 | ||
12384 | The specifications used for hosts and targets in the @code{configure} | |
12385 | script are based on a three-part naming scheme, but some short predefined | |
12386 | aliases are also supported. The full naming scheme encodes three pieces | |
12387 | of information in the following pattern: | |
12388 | ||
12389 | @example | |
12390 | @var{architecture}-@var{vendor}-@var{os} | |
12391 | @end example | |
12392 | ||
12393 | For example, you can use the alias @code{sun4} as a @var{host} argument, | |
12394 | or as the value for @var{target} in a @code{--target=@var{target}} | |
12395 | option. The equivalent full name is @samp{sparc-sun-sunos4}. | |
12396 | ||
12397 | The @code{configure} script accompanying @value{GDBN} does not provide | |
12398 | any query facility to list all supported host and target names or | |
12399 | aliases. @code{configure} calls the Bourne shell script | |
12400 | @code{config.sub} to map abbreviations to full names; you can read the | |
12401 | script, if you wish, or you can use it to test your guesses on | |
12402 | abbreviations---for example: | |
12403 | ||
12404 | @smallexample | |
12405 | % sh config.sub i386-linux | |
12406 | i386-pc-linux-gnu | |
12407 | % sh config.sub alpha-linux | |
12408 | alpha-unknown-linux-gnu | |
12409 | % sh config.sub hp9k700 | |
12410 | hppa1.1-hp-hpux | |
12411 | % sh config.sub sun4 | |
12412 | sparc-sun-sunos4.1.1 | |
12413 | % sh config.sub sun3 | |
12414 | m68k-sun-sunos4.1.1 | |
12415 | % sh config.sub i986v | |
12416 | Invalid configuration `i986v': machine `i986v' not recognized | |
12417 | @end smallexample | |
12418 | ||
12419 | @noindent | |
12420 | @code{config.sub} is also distributed in the @value{GDBN} source | |
12421 | directory (@file{gdb-@value{GDBVN}}, for version @value{GDBVN}). | |
12422 | ||
53a5351d | 12423 | @node Configure Options |
c906108c SS |
12424 | @section @code{configure} options |
12425 | ||
12426 | Here is a summary of the @code{configure} options and arguments that | |
12427 | are most often useful for building @value{GDBN}. @code{configure} also has | |
12428 | several other options not listed here. @inforef{What Configure | |
12429 | Does,,configure.info}, for a full explanation of @code{configure}. | |
12430 | ||
12431 | @example | |
12432 | configure @r{[}--help@r{]} | |
12433 | @r{[}--prefix=@var{dir}@r{]} | |
12434 | @r{[}--exec-prefix=@var{dir}@r{]} | |
12435 | @r{[}--srcdir=@var{dirname}@r{]} | |
12436 | @r{[}--norecursion@r{]} @r{[}--rm@r{]} | |
12437 | @r{[}--target=@var{target}@r{]} | |
12438 | @var{host} | |
12439 | @end example | |
12440 | ||
12441 | @noindent | |
12442 | You may introduce options with a single @samp{-} rather than | |
12443 | @samp{--} if you prefer; but you may abbreviate option names if you use | |
12444 | @samp{--}. | |
12445 | ||
12446 | @table @code | |
12447 | @item --help | |
12448 | Display a quick summary of how to invoke @code{configure}. | |
12449 | ||
12450 | @item --prefix=@var{dir} | |
12451 | Configure the source to install programs and files under directory | |
12452 | @file{@var{dir}}. | |
12453 | ||
12454 | @item --exec-prefix=@var{dir} | |
12455 | Configure the source to install programs under directory | |
12456 | @file{@var{dir}}. | |
12457 | ||
12458 | @c avoid splitting the warning from the explanation: | |
12459 | @need 2000 | |
12460 | @item --srcdir=@var{dirname} | |
12461 | @strong{Warning: using this option requires @sc{gnu} @code{make}, or another | |
12462 | @code{make} that implements the @code{VPATH} feature.}@* | |
12463 | Use this option to make configurations in directories separate from the | |
12464 | @value{GDBN} source directories. Among other things, you can use this to | |
12465 | build (or maintain) several configurations simultaneously, in separate | |
12466 | directories. @code{configure} writes configuration specific files in | |
12467 | the current directory, but arranges for them to use the source in the | |
12468 | directory @var{dirname}. @code{configure} creates directories under | |
12469 | the working directory in parallel to the source directories below | |
12470 | @var{dirname}. | |
12471 | ||
12472 | @item --norecursion | |
12473 | Configure only the directory level where @code{configure} is executed; do not | |
12474 | propagate configuration to subdirectories. | |
12475 | ||
12476 | @item --target=@var{target} | |
12477 | Configure @value{GDBN} for cross-debugging programs running on the specified | |
12478 | @var{target}. Without this option, @value{GDBN} is configured to debug | |
12479 | programs that run on the same machine (@var{host}) as @value{GDBN} itself. | |
12480 | ||
12481 | There is no convenient way to generate a list of all available targets. | |
12482 | ||
12483 | @item @var{host} @dots{} | |
12484 | Configure @value{GDBN} to run on the specified @var{host}. | |
12485 | ||
12486 | There is no convenient way to generate a list of all available hosts. | |
12487 | @end table | |
12488 | ||
12489 | There are many other options available as well, but they are generally | |
12490 | needed for special purposes only. | |
c906108c | 12491 | |
53a5351d | 12492 | @node Index |
c906108c SS |
12493 | @unnumbered Index |
12494 | ||
12495 | @printindex cp | |
12496 | ||
12497 | @tex | |
12498 | % I think something like @colophon should be in texinfo. In the | |
12499 | % meantime: | |
12500 | \long\def\colophon{\hbox to0pt{}\vfill | |
12501 | \centerline{The body of this manual is set in} | |
12502 | \centerline{\fontname\tenrm,} | |
12503 | \centerline{with headings in {\bf\fontname\tenbf}} | |
12504 | \centerline{and examples in {\tt\fontname\tentt}.} | |
12505 | \centerline{{\it\fontname\tenit\/},} | |
12506 | \centerline{{\bf\fontname\tenbf}, and} | |
12507 | \centerline{{\sl\fontname\tensl\/}} | |
12508 | \centerline{are used for emphasis.}\vfill} | |
12509 | \page\colophon | |
12510 | % Blame: doc@cygnus.com, 1991. | |
12511 | @end tex | |
12512 | ||
12513 | @contents | |
12514 | @bye |