1 \input texinfo @c -*- texinfo -*-
2 @setfilename gdbint.info
4 @dircategory Programming & development tools.
6 * Gdb-Internals: (gdbint). The GNU debugger's internals.
10 This file documents the internals of the GNU debugger @value{GDBN}.
11 Copyright 1990,1991,1992,1993,1994,1996,1998,1999,2000,2001,2002,2003
12 Free Software Foundation, Inc.
13 Contributed by Cygnus Solutions. Written by John Gilmore.
14 Second Edition by Stan Shebs.
16 Permission is granted to copy, distribute and/or modify this document
17 under the terms of the GNU Free Documentation License, Version 1.1 or
18 any later version published by the Free Software Foundation; with no
19 Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
20 Texts. A copy of the license is included in the section entitled ``GNU
21 Free Documentation License''.
24 @setchapternewpage off
25 @settitle @value{GDBN} Internals
31 @title @value{GDBN} Internals
32 @subtitle{A guide to the internals of the GNU debugger}
34 @author Cygnus Solutions
35 @author Second Edition:
37 @author Cygnus Solutions
40 \def\$#1${{#1}} % Kluge: collect RCS revision info without $...$
41 \xdef\manvers{\$Revision$} % For use in headers, footers too
43 \hfill Cygnus Solutions\par
45 \hfill \TeX{}info \texinfoversion\par
49 @vskip 0pt plus 1filll
50 Copyright @copyright{} 1990,1991,1992,1993,1994,1996,1998,1999,2000,2001,
51 2002, 2003 Free Software Foundation, Inc.
53 Permission is granted to copy, distribute and/or modify this document
54 under the terms of the GNU Free Documentation License, Version 1.1 or
55 any later version published by the Free Software Foundation; with no
56 Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
57 Texts. A copy of the license is included in the section entitled ``GNU
58 Free Documentation License''.
64 @c Perhaps this should be the title of the document (but only for info,
65 @c not for TeX). Existing GNU manuals seem inconsistent on this point.
66 @top Scope of this Document
68 This document documents the internals of the GNU debugger, @value{GDBN}. It
69 includes description of @value{GDBN}'s key algorithms and operations, as well
70 as the mechanisms that adapt @value{GDBN} to specific hosts and targets.
81 * Target Architecture Definition::
82 * Target Vector Definition::
91 * GDB Observers:: @value{GDBN} Currently available observers
92 * GNU Free Documentation License:: The license for this documentation
99 @cindex requirements for @value{GDBN}
101 Before diving into the internals, you should understand the formal
102 requirements and other expectations for @value{GDBN}. Although some
103 of these may seem obvious, there have been proposals for @value{GDBN}
104 that have run counter to these requirements.
106 First of all, @value{GDBN} is a debugger. It's not designed to be a
107 front panel for embedded systems. It's not a text editor. It's not a
108 shell. It's not a programming environment.
110 @value{GDBN} is an interactive tool. Although a batch mode is
111 available, @value{GDBN}'s primary role is to interact with a human
114 @value{GDBN} should be responsive to the user. A programmer hot on
115 the trail of a nasty bug, and operating under a looming deadline, is
116 going to be very impatient of everything, including the response time
117 to debugger commands.
119 @value{GDBN} should be relatively permissive, such as for expressions.
120 While the compiler should be picky (or have the option to be made
121 picky), since source code lives for a long time usually, the
122 programmer doing debugging shouldn't be spending time figuring out to
123 mollify the debugger.
125 @value{GDBN} will be called upon to deal with really large programs.
126 Executable sizes of 50 to 100 megabytes occur regularly, and we've
127 heard reports of programs approaching 1 gigabyte in size.
129 @value{GDBN} should be able to run everywhere. No other debugger is
130 available for even half as many configurations as @value{GDBN}
134 @node Overall Structure
136 @chapter Overall Structure
138 @value{GDBN} consists of three major subsystems: user interface,
139 symbol handling (the @dfn{symbol side}), and target system handling (the
142 The user interface consists of several actual interfaces, plus
145 The symbol side consists of object file readers, debugging info
146 interpreters, symbol table management, source language expression
147 parsing, type and value printing.
149 The target side consists of execution control, stack frame analysis, and
150 physical target manipulation.
152 The target side/symbol side division is not formal, and there are a
153 number of exceptions. For instance, core file support involves symbolic
154 elements (the basic core file reader is in BFD) and target elements (it
155 supplies the contents of memory and the values of registers). Instead,
156 this division is useful for understanding how the minor subsystems
159 @section The Symbol Side
161 The symbolic side of @value{GDBN} can be thought of as ``everything
162 you can do in @value{GDBN} without having a live program running''.
163 For instance, you can look at the types of variables, and evaluate
164 many kinds of expressions.
166 @section The Target Side
168 The target side of @value{GDBN} is the ``bits and bytes manipulator''.
169 Although it may make reference to symbolic info here and there, most
170 of the target side will run with only a stripped executable
171 available---or even no executable at all, in remote debugging cases.
173 Operations such as disassembly, stack frame crawls, and register
174 display, are able to work with no symbolic info at all. In some cases,
175 such as disassembly, @value{GDBN} will use symbolic info to present addresses
176 relative to symbols rather than as raw numbers, but it will work either
179 @section Configurations
183 @dfn{Host} refers to attributes of the system where @value{GDBN} runs.
184 @dfn{Target} refers to the system where the program being debugged
185 executes. In most cases they are the same machine, in which case a
186 third type of @dfn{Native} attributes come into play.
188 Defines and include files needed to build on the host are host support.
189 Examples are tty support, system defined types, host byte order, host
192 Defines and information needed to handle the target format are target
193 dependent. Examples are the stack frame format, instruction set,
194 breakpoint instruction, registers, and how to set up and tear down the stack
197 Information that is only needed when the host and target are the same,
198 is native dependent. One example is Unix child process support; if the
199 host and target are not the same, doing a fork to start the target
200 process is a bad idea. The various macros needed for finding the
201 registers in the @code{upage}, running @code{ptrace}, and such are all
202 in the native-dependent files.
204 Another example of native-dependent code is support for features that
205 are really part of the target environment, but which require
206 @code{#include} files that are only available on the host system. Core
207 file handling and @code{setjmp} handling are two common cases.
209 When you want to make @value{GDBN} work ``native'' on a particular machine, you
210 have to include all three kinds of information.
218 @value{GDBN} uses a number of debugging-specific algorithms. They are
219 often not very complicated, but get lost in the thicket of special
220 cases and real-world issues. This chapter describes the basic
221 algorithms and mentions some of the specific target definitions that
227 @cindex call stack frame
228 A frame is a construct that @value{GDBN} uses to keep track of calling
229 and called functions.
231 @findex create_new_frame
233 @code{FRAME_FP} in the machine description has no meaning to the
234 machine-independent part of @value{GDBN}, except that it is used when
235 setting up a new frame from scratch, as follows:
238 create_new_frame (read_register (DEPRECATED_FP_REGNUM), read_pc ()));
241 @cindex frame pointer register
242 Other than that, all the meaning imparted to @code{DEPRECATED_FP_REGNUM}
243 is imparted by the machine-dependent code. So,
244 @code{DEPRECATED_FP_REGNUM} can have any value that is convenient for
245 the code that creates new frames. (@code{create_new_frame} calls
246 @code{DEPRECATED_INIT_EXTRA_FRAME_INFO} if it is defined; that is where
247 you should use the @code{DEPRECATED_FP_REGNUM} value, if your frames are
251 Given a @value{GDBN} frame, define @code{DEPRECATED_FRAME_CHAIN} to
252 determine the address of the calling function's frame. This will be
253 used to create a new @value{GDBN} frame struct, and then
254 @code{DEPRECATED_INIT_EXTRA_FRAME_INFO} and
255 @code{DEPRECATED_INIT_FRAME_PC} will be called for the new frame.
257 @section Breakpoint Handling
260 In general, a breakpoint is a user-designated location in the program
261 where the user wants to regain control if program execution ever reaches
264 There are two main ways to implement breakpoints; either as ``hardware''
265 breakpoints or as ``software'' breakpoints.
267 @cindex hardware breakpoints
268 @cindex program counter
269 Hardware breakpoints are sometimes available as a builtin debugging
270 features with some chips. Typically these work by having dedicated
271 register into which the breakpoint address may be stored. If the PC
272 (shorthand for @dfn{program counter})
273 ever matches a value in a breakpoint registers, the CPU raises an
274 exception and reports it to @value{GDBN}.
276 Another possibility is when an emulator is in use; many emulators
277 include circuitry that watches the address lines coming out from the
278 processor, and force it to stop if the address matches a breakpoint's
281 A third possibility is that the target already has the ability to do
282 breakpoints somehow; for instance, a ROM monitor may do its own
283 software breakpoints. So although these are not literally ``hardware
284 breakpoints'', from @value{GDBN}'s point of view they work the same;
285 @value{GDBN} need not do anything more than set the breakpoint and wait
286 for something to happen.
288 Since they depend on hardware resources, hardware breakpoints may be
289 limited in number; when the user asks for more, @value{GDBN} will
290 start trying to set software breakpoints. (On some architectures,
291 notably the 32-bit x86 platforms, @value{GDBN} cannot always know
292 whether there's enough hardware resources to insert all the hardware
293 breakpoints and watchpoints. On those platforms, @value{GDBN} prints
294 an error message only when the program being debugged is continued.)
296 @cindex software breakpoints
297 Software breakpoints require @value{GDBN} to do somewhat more work.
298 The basic theory is that @value{GDBN} will replace a program
299 instruction with a trap, illegal divide, or some other instruction
300 that will cause an exception, and then when it's encountered,
301 @value{GDBN} will take the exception and stop the program. When the
302 user says to continue, @value{GDBN} will restore the original
303 instruction, single-step, re-insert the trap, and continue on.
305 Since it literally overwrites the program being tested, the program area
306 must be writable, so this technique won't work on programs in ROM. It
307 can also distort the behavior of programs that examine themselves,
308 although such a situation would be highly unusual.
310 Also, the software breakpoint instruction should be the smallest size of
311 instruction, so it doesn't overwrite an instruction that might be a jump
312 target, and cause disaster when the program jumps into the middle of the
313 breakpoint instruction. (Strictly speaking, the breakpoint must be no
314 larger than the smallest interval between instructions that may be jump
315 targets; perhaps there is an architecture where only even-numbered
316 instructions may jumped to.) Note that it's possible for an instruction
317 set not to have any instructions usable for a software breakpoint,
318 although in practice only the ARC has failed to define such an
322 The basic definition of the software breakpoint is the macro
325 Basic breakpoint object handling is in @file{breakpoint.c}. However,
326 much of the interesting breakpoint action is in @file{infrun.c}.
328 @section Single Stepping
330 @section Signal Handling
332 @section Thread Handling
334 @section Inferior Function Calls
336 @section Longjmp Support
338 @cindex @code{longjmp} debugging
339 @value{GDBN} has support for figuring out that the target is doing a
340 @code{longjmp} and for stopping at the target of the jump, if we are
341 stepping. This is done with a few specialized internal breakpoints,
342 which are visible in the output of the @samp{maint info breakpoint}
345 @findex GET_LONGJMP_TARGET
346 To make this work, you need to define a macro called
347 @code{GET_LONGJMP_TARGET}, which will examine the @code{jmp_buf}
348 structure and extract the longjmp target address. Since @code{jmp_buf}
349 is target specific, you will need to define it in the appropriate
350 @file{tm-@var{target}.h} file. Look in @file{tm-sun4os4.h} and
351 @file{sparc-tdep.c} for examples of how to do this.
356 Watchpoints are a special kind of breakpoints (@pxref{Algorithms,
357 breakpoints}) which break when data is accessed rather than when some
358 instruction is executed. When you have data which changes without
359 your knowing what code does that, watchpoints are the silver bullet to
360 hunt down and kill such bugs.
362 @cindex hardware watchpoints
363 @cindex software watchpoints
364 Watchpoints can be either hardware-assisted or not; the latter type is
365 known as ``software watchpoints.'' @value{GDBN} always uses
366 hardware-assisted watchpoints if they are available, and falls back on
367 software watchpoints otherwise. Typical situations where @value{GDBN}
368 will use software watchpoints are:
372 The watched memory region is too large for the underlying hardware
373 watchpoint support. For example, each x86 debug register can watch up
374 to 4 bytes of memory, so trying to watch data structures whose size is
375 more than 16 bytes will cause @value{GDBN} to use software
379 The value of the expression to be watched depends on data held in
380 registers (as opposed to memory).
383 Too many different watchpoints requested. (On some architectures,
384 this situation is impossible to detect until the debugged program is
385 resumed.) Note that x86 debug registers are used both for hardware
386 breakpoints and for watchpoints, so setting too many hardware
387 breakpoints might cause watchpoint insertion to fail.
390 No hardware-assisted watchpoints provided by the target
394 Software watchpoints are very slow, since @value{GDBN} needs to
395 single-step the program being debugged and test the value of the
396 watched expression(s) after each instruction. The rest of this
397 section is mostly irrelevant for software watchpoints.
399 @value{GDBN} uses several macros and primitives to support hardware
403 @findex TARGET_HAS_HARDWARE_WATCHPOINTS
404 @item TARGET_HAS_HARDWARE_WATCHPOINTS
405 If defined, the target supports hardware watchpoints.
407 @findex TARGET_CAN_USE_HARDWARE_WATCHPOINT
408 @item TARGET_CAN_USE_HARDWARE_WATCHPOINT (@var{type}, @var{count}, @var{other})
409 Return the number of hardware watchpoints of type @var{type} that are
410 possible to be set. The value is positive if @var{count} watchpoints
411 of this type can be set, zero if setting watchpoints of this type is
412 not supported, and negative if @var{count} is more than the maximum
413 number of watchpoints of type @var{type} that can be set. @var{other}
414 is non-zero if other types of watchpoints are currently enabled (there
415 are architectures which cannot set watchpoints of different types at
418 @findex TARGET_REGION_OK_FOR_HW_WATCHPOINT
419 @item TARGET_REGION_OK_FOR_HW_WATCHPOINT (@var{addr}, @var{len})
420 Return non-zero if hardware watchpoints can be used to watch a region
421 whose address is @var{addr} and whose length in bytes is @var{len}.
423 @findex TARGET_REGION_SIZE_OK_FOR_HW_WATCHPOINT
424 @item TARGET_REGION_SIZE_OK_FOR_HW_WATCHPOINT (@var{size})
425 Return non-zero if hardware watchpoints can be used to watch a region
426 whose size is @var{size}. @value{GDBN} only uses this macro as a
427 fall-back, in case @code{TARGET_REGION_OK_FOR_HW_WATCHPOINT} is not
430 @findex TARGET_DISABLE_HW_WATCHPOINTS
431 @item TARGET_DISABLE_HW_WATCHPOINTS (@var{pid})
432 Disables watchpoints in the process identified by @var{pid}. This is
433 used, e.g., on HP-UX which provides operations to disable and enable
434 the page-level memory protection that implements hardware watchpoints
437 @findex TARGET_ENABLE_HW_WATCHPOINTS
438 @item TARGET_ENABLE_HW_WATCHPOINTS (@var{pid})
439 Enables watchpoints in the process identified by @var{pid}. This is
440 used, e.g., on HP-UX which provides operations to disable and enable
441 the page-level memory protection that implements hardware watchpoints
444 @findex target_insert_watchpoint
445 @findex target_remove_watchpoint
446 @item target_insert_watchpoint (@var{addr}, @var{len}, @var{type})
447 @itemx target_remove_watchpoint (@var{addr}, @var{len}, @var{type})
448 Insert or remove a hardware watchpoint starting at @var{addr}, for
449 @var{len} bytes. @var{type} is the watchpoint type, one of the
450 possible values of the enumerated data type @code{target_hw_bp_type},
451 defined by @file{breakpoint.h} as follows:
454 enum target_hw_bp_type
456 hw_write = 0, /* Common (write) HW watchpoint */
457 hw_read = 1, /* Read HW watchpoint */
458 hw_access = 2, /* Access (read or write) HW watchpoint */
459 hw_execute = 3 /* Execute HW breakpoint */
464 These two macros should return 0 for success, non-zero for failure.
466 @cindex insert or remove hardware breakpoint
467 @findex target_remove_hw_breakpoint
468 @findex target_insert_hw_breakpoint
469 @item target_remove_hw_breakpoint (@var{addr}, @var{shadow})
470 @itemx target_insert_hw_breakpoint (@var{addr}, @var{shadow})
471 Insert or remove a hardware-assisted breakpoint at address @var{addr}.
472 Returns zero for success, non-zero for failure. @var{shadow} is the
473 real contents of the byte where the breakpoint has been inserted; it
474 is generally not valid when hardware breakpoints are used, but since
475 no other code touches these values, the implementations of the above
476 two macros can use them for their internal purposes.
478 @findex target_stopped_data_address
479 @item target_stopped_data_address ()
480 If the inferior has some watchpoint that triggered, return the address
481 associated with that watchpoint. Otherwise, return zero.
483 @findex DECR_PC_AFTER_HW_BREAK
484 @item DECR_PC_AFTER_HW_BREAK
485 If defined, @value{GDBN} decrements the program counter by the value
486 of @code{DECR_PC_AFTER_HW_BREAK} after a hardware break-point. This
487 overrides the value of @code{DECR_PC_AFTER_BREAK} when a breakpoint
488 that breaks is a hardware-assisted breakpoint.
490 @findex HAVE_STEPPABLE_WATCHPOINT
491 @item HAVE_STEPPABLE_WATCHPOINT
492 If defined to a non-zero value, it is not necessary to disable a
493 watchpoint to step over it.
495 @findex HAVE_NONSTEPPABLE_WATCHPOINT
496 @item HAVE_NONSTEPPABLE_WATCHPOINT
497 If defined to a non-zero value, @value{GDBN} should disable a
498 watchpoint to step the inferior over it.
500 @findex HAVE_CONTINUABLE_WATCHPOINT
501 @item HAVE_CONTINUABLE_WATCHPOINT
502 If defined to a non-zero value, it is possible to continue the
503 inferior after a watchpoint has been hit.
505 @findex CANNOT_STEP_HW_WATCHPOINTS
506 @item CANNOT_STEP_HW_WATCHPOINTS
507 If this is defined to a non-zero value, @value{GDBN} will remove all
508 watchpoints before stepping the inferior.
510 @findex STOPPED_BY_WATCHPOINT
511 @item STOPPED_BY_WATCHPOINT (@var{wait_status})
512 Return non-zero if stopped by a watchpoint. @var{wait_status} is of
513 the type @code{struct target_waitstatus}, defined by @file{target.h}.
516 @subsection x86 Watchpoints
517 @cindex x86 debug registers
518 @cindex watchpoints, on x86
520 The 32-bit Intel x86 (a.k.a.@: ia32) processors feature special debug
521 registers designed to facilitate debugging. @value{GDBN} provides a
522 generic library of functions that x86-based ports can use to implement
523 support for watchpoints and hardware-assisted breakpoints. This
524 subsection documents the x86 watchpoint facilities in @value{GDBN}.
526 To use the generic x86 watchpoint support, a port should do the
530 @findex I386_USE_GENERIC_WATCHPOINTS
532 Define the macro @code{I386_USE_GENERIC_WATCHPOINTS} somewhere in the
533 target-dependent headers.
536 Include the @file{config/i386/nm-i386.h} header file @emph{after}
537 defining @code{I386_USE_GENERIC_WATCHPOINTS}.
540 Add @file{i386-nat.o} to the value of the Make variable
541 @code{NATDEPFILES} (@pxref{Native Debugging, NATDEPFILES}) or
542 @code{TDEPFILES} (@pxref{Target Architecture Definition, TDEPFILES}).
545 Provide implementations for the @code{I386_DR_LOW_*} macros described
546 below. Typically, each macro should call a target-specific function
547 which does the real work.
550 The x86 watchpoint support works by maintaining mirror images of the
551 debug registers. Values are copied between the mirror images and the
552 real debug registers via a set of macros which each target needs to
556 @findex I386_DR_LOW_SET_CONTROL
557 @item I386_DR_LOW_SET_CONTROL (@var{val})
558 Set the Debug Control (DR7) register to the value @var{val}.
560 @findex I386_DR_LOW_SET_ADDR
561 @item I386_DR_LOW_SET_ADDR (@var{idx}, @var{addr})
562 Put the address @var{addr} into the debug register number @var{idx}.
564 @findex I386_DR_LOW_RESET_ADDR
565 @item I386_DR_LOW_RESET_ADDR (@var{idx})
566 Reset (i.e.@: zero out) the address stored in the debug register
569 @findex I386_DR_LOW_GET_STATUS
570 @item I386_DR_LOW_GET_STATUS
571 Return the value of the Debug Status (DR6) register. This value is
572 used immediately after it is returned by
573 @code{I386_DR_LOW_GET_STATUS}, so as to support per-thread status
577 For each one of the 4 debug registers (whose indices are from 0 to 3)
578 that store addresses, a reference count is maintained by @value{GDBN},
579 to allow sharing of debug registers by several watchpoints. This
580 allows users to define several watchpoints that watch the same
581 expression, but with different conditions and/or commands, without
582 wasting debug registers which are in short supply. @value{GDBN}
583 maintains the reference counts internally, targets don't have to do
584 anything to use this feature.
586 The x86 debug registers can each watch a region that is 1, 2, or 4
587 bytes long. The ia32 architecture requires that each watched region
588 be appropriately aligned: 2-byte region on 2-byte boundary, 4-byte
589 region on 4-byte boundary. However, the x86 watchpoint support in
590 @value{GDBN} can watch unaligned regions and regions larger than 4
591 bytes (up to 16 bytes) by allocating several debug registers to watch
592 a single region. This allocation of several registers per a watched
593 region is also done automatically without target code intervention.
595 The generic x86 watchpoint support provides the following API for the
596 @value{GDBN}'s application code:
599 @findex i386_region_ok_for_watchpoint
600 @item i386_region_ok_for_watchpoint (@var{addr}, @var{len})
601 The macro @code{TARGET_REGION_OK_FOR_HW_WATCHPOINT} is set to call
602 this function. It counts the number of debug registers required to
603 watch a given region, and returns a non-zero value if that number is
604 less than 4, the number of debug registers available to x86
607 @findex i386_stopped_data_address
608 @item i386_stopped_data_address (void)
609 The macros @code{STOPPED_BY_WATCHPOINT} and
610 @code{target_stopped_data_address} are set to call this function. The
611 argument passed to @code{STOPPED_BY_WATCHPOINT} is ignored. This
612 function examines the breakpoint condition bits in the DR6 Debug
613 Status register, as returned by the @code{I386_DR_LOW_GET_STATUS}
614 macro, and returns the address associated with the first bit that is
617 @findex i386_insert_watchpoint
618 @findex i386_remove_watchpoint
619 @item i386_insert_watchpoint (@var{addr}, @var{len}, @var{type})
620 @itemx i386_remove_watchpoint (@var{addr}, @var{len}, @var{type})
621 Insert or remove a watchpoint. The macros
622 @code{target_insert_watchpoint} and @code{target_remove_watchpoint}
623 are set to call these functions. @code{i386_insert_watchpoint} first
624 looks for a debug register which is already set to watch the same
625 region for the same access types; if found, it just increments the
626 reference count of that debug register, thus implementing debug
627 register sharing between watchpoints. If no such register is found,
628 the function looks for a vacant debug register, sets its mirrored
629 value to @var{addr}, sets the mirrored value of DR7 Debug Control
630 register as appropriate for the @var{len} and @var{type} parameters,
631 and then passes the new values of the debug register and DR7 to the
632 inferior by calling @code{I386_DR_LOW_SET_ADDR} and
633 @code{I386_DR_LOW_SET_CONTROL}. If more than one debug register is
634 required to cover the given region, the above process is repeated for
637 @code{i386_remove_watchpoint} does the opposite: it resets the address
638 in the mirrored value of the debug register and its read/write and
639 length bits in the mirrored value of DR7, then passes these new
640 values to the inferior via @code{I386_DR_LOW_RESET_ADDR} and
641 @code{I386_DR_LOW_SET_CONTROL}. If a register is shared by several
642 watchpoints, each time a @code{i386_remove_watchpoint} is called, it
643 decrements the reference count, and only calls
644 @code{I386_DR_LOW_RESET_ADDR} and @code{I386_DR_LOW_SET_CONTROL} when
645 the count goes to zero.
647 @findex i386_insert_hw_breakpoint
648 @findex i386_remove_hw_breakpoint
649 @item i386_insert_hw_breakpoint (@var{addr}, @var{shadow}
650 @itemx i386_remove_hw_breakpoint (@var{addr}, @var{shadow})
651 These functions insert and remove hardware-assisted breakpoints. The
652 macros @code{target_insert_hw_breakpoint} and
653 @code{target_remove_hw_breakpoint} are set to call these functions.
654 These functions work like @code{i386_insert_watchpoint} and
655 @code{i386_remove_watchpoint}, respectively, except that they set up
656 the debug registers to watch instruction execution, and each
657 hardware-assisted breakpoint always requires exactly one debug
660 @findex i386_stopped_by_hwbp
661 @item i386_stopped_by_hwbp (void)
662 This function returns non-zero if the inferior has some watchpoint or
663 hardware breakpoint that triggered. It works like
664 @code{i386_stopped_data_address}, except that it doesn't return the
665 address whose watchpoint triggered.
667 @findex i386_cleanup_dregs
668 @item i386_cleanup_dregs (void)
669 This function clears all the reference counts, addresses, and control
670 bits in the mirror images of the debug registers. It doesn't affect
671 the actual debug registers in the inferior process.
678 x86 processors support setting watchpoints on I/O reads or writes.
679 However, since no target supports this (as of March 2001), and since
680 @code{enum target_hw_bp_type} doesn't even have an enumeration for I/O
681 watchpoints, this feature is not yet available to @value{GDBN} running
685 x86 processors can enable watchpoints locally, for the current task
686 only, or globally, for all the tasks. For each debug register,
687 there's a bit in the DR7 Debug Control register that determines
688 whether the associated address is watched locally or globally. The
689 current implementation of x86 watchpoint support in @value{GDBN}
690 always sets watchpoints to be locally enabled, since global
691 watchpoints might interfere with the underlying OS and are probably
692 unavailable in many platforms.
695 @section Observing changes in @value{GDBN} internals
696 @cindex observer pattern interface
697 @cindex notifications about changes in internals
699 In order to function properly, several modules need to be notified when
700 some changes occur in the @value{GDBN} internals. Traditionally, these
701 modules have relied on several paradigms, the most common ones being
702 hooks and gdb-events. Unfortunately, none of these paradigms was
703 versatile enough to become the standard notification mechanism in
704 @value{GDBN}. The fact that they only supported one ``client'' was also
707 A new paradigm, based on the Observer pattern of the @cite{Design
708 Patterns} book, has therefore been implemented. The goal was to provide
709 a new interface overcoming the issues with the notification mechanisms
710 previously available. This new interface needed to be strongly typed,
711 easy to extend, and versatile enough to be used as the standard
712 interface when adding new notifications.
714 See @ref{GDB Observers} for a brief description of the observers
715 currently implemented in GDB. The rationale for the current
716 implementation is also briefly discussed.
720 @chapter User Interface
722 @value{GDBN} has several user interfaces. Although the command-line interface
723 is the most common and most familiar, there are others.
725 @section Command Interpreter
727 @cindex command interpreter
729 The command interpreter in @value{GDBN} is fairly simple. It is designed to
730 allow for the set of commands to be augmented dynamically, and also
731 has a recursive subcommand capability, where the first argument to
732 a command may itself direct a lookup on a different command list.
734 For instance, the @samp{set} command just starts a lookup on the
735 @code{setlist} command list, while @samp{set thread} recurses
736 to the @code{set_thread_cmd_list}.
740 To add commands in general, use @code{add_cmd}. @code{add_com} adds to
741 the main command list, and should be used for those commands. The usual
742 place to add commands is in the @code{_initialize_@var{xyz}} routines at
743 the ends of most source files.
745 @findex add_setshow_cmd
746 @findex add_setshow_cmd_full
747 To add paired @samp{set} and @samp{show} commands, use
748 @code{add_setshow_cmd} or @code{add_setshow_cmd_full}. The former is
749 a slightly simpler interface which is useful when you don't need to
750 further modify the new command structures, while the latter returns
751 the new command structures for manipulation.
753 @cindex deprecating commands
754 @findex deprecate_cmd
755 Before removing commands from the command set it is a good idea to
756 deprecate them for some time. Use @code{deprecate_cmd} on commands or
757 aliases to set the deprecated flag. @code{deprecate_cmd} takes a
758 @code{struct cmd_list_element} as it's first argument. You can use the
759 return value from @code{add_com} or @code{add_cmd} to deprecate the
760 command immediately after it is created.
762 The first time a command is used the user will be warned and offered a
763 replacement (if one exists). Note that the replacement string passed to
764 @code{deprecate_cmd} should be the full name of the command, i.e. the
765 entire string the user should type at the command line.
767 @section UI-Independent Output---the @code{ui_out} Functions
768 @c This section is based on the documentation written by Fernando
769 @c Nasser <fnasser@redhat.com>.
771 @cindex @code{ui_out} functions
772 The @code{ui_out} functions present an abstraction level for the
773 @value{GDBN} output code. They hide the specifics of different user
774 interfaces supported by @value{GDBN}, and thus free the programmer
775 from the need to write several versions of the same code, one each for
776 every UI, to produce output.
778 @subsection Overview and Terminology
780 In general, execution of each @value{GDBN} command produces some sort
781 of output, and can even generate an input request.
783 Output can be generated for the following purposes:
787 to display a @emph{result} of an operation;
790 to convey @emph{info} or produce side-effects of a requested
794 to provide a @emph{notification} of an asynchronous event (including
795 progress indication of a prolonged asynchronous operation);
798 to display @emph{error messages} (including warnings);
801 to show @emph{debug data};
804 to @emph{query} or prompt a user for input (a special case).
808 This section mainly concentrates on how to build result output,
809 although some of it also applies to other kinds of output.
811 Generation of output that displays the results of an operation
812 involves one or more of the following:
816 output of the actual data
819 formatting the output as appropriate for console output, to make it
820 easily readable by humans
823 machine oriented formatting--a more terse formatting to allow for easy
824 parsing by programs which read @value{GDBN}'s output
827 annotation, whose purpose is to help legacy GUIs to identify interesting
831 The @code{ui_out} routines take care of the first three aspects.
832 Annotations are provided by separate annotation routines. Note that use
833 of annotations for an interface between a GUI and @value{GDBN} is
836 Output can be in the form of a single item, which we call a @dfn{field};
837 a @dfn{list} consisting of identical fields; a @dfn{tuple} consisting of
838 non-identical fields; or a @dfn{table}, which is a tuple consisting of a
839 header and a body. In a BNF-like form:
842 @item <table> @expansion{}
843 @code{<header> <body>}
844 @item <header> @expansion{}
845 @code{@{ <column> @}}
846 @item <column> @expansion{}
847 @code{<width> <alignment> <title>}
848 @item <body> @expansion{}
853 @subsection General Conventions
855 Most @code{ui_out} routines are of type @code{void}, the exceptions are
856 @code{ui_out_stream_new} (which returns a pointer to the newly created
857 object) and the @code{make_cleanup} routines.
859 The first parameter is always the @code{ui_out} vector object, a pointer
860 to a @code{struct ui_out}.
862 The @var{format} parameter is like in @code{printf} family of functions.
863 When it is present, there must also be a variable list of arguments
864 sufficient used to satisfy the @code{%} specifiers in the supplied
867 When a character string argument is not used in a @code{ui_out} function
868 call, a @code{NULL} pointer has to be supplied instead.
871 @subsection Table, Tuple and List Functions
873 @cindex list output functions
874 @cindex table output functions
875 @cindex tuple output functions
876 This section introduces @code{ui_out} routines for building lists,
877 tuples and tables. The routines to output the actual data items
878 (fields) are presented in the next section.
880 To recap: A @dfn{tuple} is a sequence of @dfn{fields}, each field
881 containing information about an object; a @dfn{list} is a sequence of
882 fields where each field describes an identical object.
884 Use the @dfn{table} functions when your output consists of a list of
885 rows (tuples) and the console output should include a heading. Use this
886 even when you are listing just one object but you still want the header.
888 @cindex nesting level in @code{ui_out} functions
889 Tables can not be nested. Tuples and lists can be nested up to a
890 maximum of five levels.
892 The overall structure of the table output code is something like this:
907 Here is the description of table-, tuple- and list-related @code{ui_out}
910 @deftypefun void ui_out_table_begin (struct ui_out *@var{uiout}, int @var{nbrofcols}, int @var{nr_rows}, const char *@var{tblid})
911 The function @code{ui_out_table_begin} marks the beginning of the output
912 of a table. It should always be called before any other @code{ui_out}
913 function for a given table. @var{nbrofcols} is the number of columns in
914 the table. @var{nr_rows} is the number of rows in the table.
915 @var{tblid} is an optional string identifying the table. The string
916 pointed to by @var{tblid} is copied by the implementation of
917 @code{ui_out_table_begin}, so the application can free the string if it
920 The companion function @code{ui_out_table_end}, described below, marks
921 the end of the table's output.
924 @deftypefun void ui_out_table_header (struct ui_out *@var{uiout}, int @var{width}, enum ui_align @var{alignment}, const char *@var{colhdr})
925 @code{ui_out_table_header} provides the header information for a single
926 table column. You call this function several times, one each for every
927 column of the table, after @code{ui_out_table_begin}, but before
928 @code{ui_out_table_body}.
930 The value of @var{width} gives the column width in characters. The
931 value of @var{alignment} is one of @code{left}, @code{center}, and
932 @code{right}, and it specifies how to align the header: left-justify,
933 center, or right-justify it. @var{colhdr} points to a string that
934 specifies the column header; the implementation copies that string, so
935 column header strings in @code{malloc}ed storage can be freed after the
939 @deftypefun void ui_out_table_body (struct ui_out *@var{uiout})
940 This function delimits the table header from the table body.
943 @deftypefun void ui_out_table_end (struct ui_out *@var{uiout})
944 This function signals the end of a table's output. It should be called
945 after the table body has been produced by the list and field output
948 There should be exactly one call to @code{ui_out_table_end} for each
949 call to @code{ui_out_table_begin}, otherwise the @code{ui_out} functions
950 will signal an internal error.
953 The output of the tuples that represent the table rows must follow the
954 call to @code{ui_out_table_body} and precede the call to
955 @code{ui_out_table_end}. You build a tuple by calling
956 @code{ui_out_tuple_begin} and @code{ui_out_tuple_end}, with suitable
957 calls to functions which actually output fields between them.
959 @deftypefun void ui_out_tuple_begin (struct ui_out *@var{uiout}, const char *@var{id})
960 This function marks the beginning of a tuple output. @var{id} points
961 to an optional string that identifies the tuple; it is copied by the
962 implementation, and so strings in @code{malloc}ed storage can be freed
966 @deftypefun void ui_out_tuple_end (struct ui_out *@var{uiout})
967 This function signals an end of a tuple output. There should be exactly
968 one call to @code{ui_out_tuple_end} for each call to
969 @code{ui_out_tuple_begin}, otherwise an internal @value{GDBN} error will
973 @deftypefun struct cleanup *make_cleanup_ui_out_tuple_begin_end (struct ui_out *@var{uiout}, const char *@var{id})
974 This function first opens the tuple and then establishes a cleanup
975 (@pxref{Coding, Cleanups}) to close the tuple. It provides a convenient
976 and correct implementation of the non-portable@footnote{The function
977 cast is not portable ISO C.} code sequence:
979 struct cleanup *old_cleanup;
980 ui_out_tuple_begin (uiout, "...");
981 old_cleanup = make_cleanup ((void(*)(void *)) ui_out_tuple_end,
986 @deftypefun void ui_out_list_begin (struct ui_out *@var{uiout}, const char *@var{id})
987 This function marks the beginning of a list output. @var{id} points to
988 an optional string that identifies the list; it is copied by the
989 implementation, and so strings in @code{malloc}ed storage can be freed
993 @deftypefun void ui_out_list_end (struct ui_out *@var{uiout})
994 This function signals an end of a list output. There should be exactly
995 one call to @code{ui_out_list_end} for each call to
996 @code{ui_out_list_begin}, otherwise an internal @value{GDBN} error will
1000 @deftypefun struct cleanup *make_cleanup_ui_out_list_begin_end (struct ui_out *@var{uiout}, const char *@var{id})
1001 Similar to @code{make_cleanup_ui_out_tuple_begin_end}, this function
1002 opens a list and then establishes cleanup (@pxref{Coding, Cleanups})
1003 that will close the list.list.
1006 @subsection Item Output Functions
1008 @cindex item output functions
1009 @cindex field output functions
1011 The functions described below produce output for the actual data
1012 items, or fields, which contain information about the object.
1014 Choose the appropriate function accordingly to your particular needs.
1016 @deftypefun void ui_out_field_fmt (struct ui_out *@var{uiout}, char *@var{fldname}, char *@var{format}, ...)
1017 This is the most general output function. It produces the
1018 representation of the data in the variable-length argument list
1019 according to formatting specifications in @var{format}, a
1020 @code{printf}-like format string. The optional argument @var{fldname}
1021 supplies the name of the field. The data items themselves are
1022 supplied as additional arguments after @var{format}.
1024 This generic function should be used only when it is not possible to
1025 use one of the specialized versions (see below).
1028 @deftypefun void ui_out_field_int (struct ui_out *@var{uiout}, const char *@var{fldname}, int @var{value})
1029 This function outputs a value of an @code{int} variable. It uses the
1030 @code{"%d"} output conversion specification. @var{fldname} specifies
1031 the name of the field.
1034 @deftypefun void ui_out_field_fmt_int (struct ui_out *@var{uiout}, int @var{width}, enum ui_align @var{alignment}, const char *@var{fldname}, int @var{value})
1035 This function outputs a value of an @code{int} variable. It differs from
1036 @code{ui_out_field_int} in that the caller specifies the desired @var{width} and @var{alignment} of the output.
1037 @var{fldname} specifies
1038 the name of the field.
1041 @deftypefun void ui_out_field_core_addr (struct ui_out *@var{uiout}, const char *@var{fldname}, CORE_ADDR @var{address})
1042 This function outputs an address.
1045 @deftypefun void ui_out_field_string (struct ui_out *@var{uiout}, const char *@var{fldname}, const char *@var{string})
1046 This function outputs a string using the @code{"%s"} conversion
1050 Sometimes, there's a need to compose your output piece by piece using
1051 functions that operate on a stream, such as @code{value_print} or
1052 @code{fprintf_symbol_filtered}. These functions accept an argument of
1053 the type @code{struct ui_file *}, a pointer to a @code{ui_file} object
1054 used to store the data stream used for the output. When you use one
1055 of these functions, you need a way to pass their results stored in a
1056 @code{ui_file} object to the @code{ui_out} functions. To this end,
1057 you first create a @code{ui_stream} object by calling
1058 @code{ui_out_stream_new}, pass the @code{stream} member of that
1059 @code{ui_stream} object to @code{value_print} and similar functions,
1060 and finally call @code{ui_out_field_stream} to output the field you
1061 constructed. When the @code{ui_stream} object is no longer needed,
1062 you should destroy it and free its memory by calling
1063 @code{ui_out_stream_delete}.
1065 @deftypefun struct ui_stream *ui_out_stream_new (struct ui_out *@var{uiout})
1066 This function creates a new @code{ui_stream} object which uses the
1067 same output methods as the @code{ui_out} object whose pointer is
1068 passed in @var{uiout}. It returns a pointer to the newly created
1069 @code{ui_stream} object.
1072 @deftypefun void ui_out_stream_delete (struct ui_stream *@var{streambuf})
1073 This functions destroys a @code{ui_stream} object specified by
1077 @deftypefun void ui_out_field_stream (struct ui_out *@var{uiout}, const char *@var{fieldname}, struct ui_stream *@var{streambuf})
1078 This function consumes all the data accumulated in
1079 @code{streambuf->stream} and outputs it like
1080 @code{ui_out_field_string} does. After a call to
1081 @code{ui_out_field_stream}, the accumulated data no longer exists, but
1082 the stream is still valid and may be used for producing more fields.
1085 @strong{Important:} If there is any chance that your code could bail
1086 out before completing output generation and reaching the point where
1087 @code{ui_out_stream_delete} is called, it is necessary to set up a
1088 cleanup, to avoid leaking memory and other resources. Here's a
1089 skeleton code to do that:
1092 struct ui_stream *mybuf = ui_out_stream_new (uiout);
1093 struct cleanup *old = make_cleanup (ui_out_stream_delete, mybuf);
1098 If the function already has the old cleanup chain set (for other kinds
1099 of cleanups), you just have to add your cleanup to it:
1102 mybuf = ui_out_stream_new (uiout);
1103 make_cleanup (ui_out_stream_delete, mybuf);
1106 Note that with cleanups in place, you should not call
1107 @code{ui_out_stream_delete} directly, or you would attempt to free the
1110 @subsection Utility Output Functions
1112 @deftypefun void ui_out_field_skip (struct ui_out *@var{uiout}, const char *@var{fldname})
1113 This function skips a field in a table. Use it if you have to leave
1114 an empty field without disrupting the table alignment. The argument
1115 @var{fldname} specifies a name for the (missing) filed.
1118 @deftypefun void ui_out_text (struct ui_out *@var{uiout}, const char *@var{string})
1119 This function outputs the text in @var{string} in a way that makes it
1120 easy to be read by humans. For example, the console implementation of
1121 this method filters the text through a built-in pager, to prevent it
1122 from scrolling off the visible portion of the screen.
1124 Use this function for printing relatively long chunks of text around
1125 the actual field data: the text it produces is not aligned according
1126 to the table's format. Use @code{ui_out_field_string} to output a
1127 string field, and use @code{ui_out_message}, described below, to
1128 output short messages.
1131 @deftypefun void ui_out_spaces (struct ui_out *@var{uiout}, int @var{nspaces})
1132 This function outputs @var{nspaces} spaces. It is handy to align the
1133 text produced by @code{ui_out_text} with the rest of the table or
1137 @deftypefun void ui_out_message (struct ui_out *@var{uiout}, int @var{verbosity}, const char *@var{format}, ...)
1138 This function produces a formatted message, provided that the current
1139 verbosity level is at least as large as given by @var{verbosity}. The
1140 current verbosity level is specified by the user with the @samp{set
1141 verbositylevel} command.@footnote{As of this writing (April 2001),
1142 setting verbosity level is not yet implemented, and is always returned
1143 as zero. So calling @code{ui_out_message} with a @var{verbosity}
1144 argument more than zero will cause the message to never be printed.}
1147 @deftypefun void ui_out_wrap_hint (struct ui_out *@var{uiout}, char *@var{indent})
1148 This function gives the console output filter (a paging filter) a hint
1149 of where to break lines which are too long. Ignored for all other
1150 output consumers. @var{indent}, if non-@code{NULL}, is the string to
1151 be printed to indent the wrapped text on the next line; it must remain
1152 accessible until the next call to @code{ui_out_wrap_hint}, or until an
1153 explicit newline is produced by one of the other functions. If
1154 @var{indent} is @code{NULL}, the wrapped text will not be indented.
1157 @deftypefun void ui_out_flush (struct ui_out *@var{uiout})
1158 This function flushes whatever output has been accumulated so far, if
1159 the UI buffers output.
1163 @subsection Examples of Use of @code{ui_out} functions
1165 @cindex using @code{ui_out} functions
1166 @cindex @code{ui_out} functions, usage examples
1167 This section gives some practical examples of using the @code{ui_out}
1168 functions to generalize the old console-oriented code in
1169 @value{GDBN}. The examples all come from functions defined on the
1170 @file{breakpoints.c} file.
1172 This example, from the @code{breakpoint_1} function, shows how to
1175 The original code was:
1178 if (!found_a_breakpoint++)
1180 annotate_breakpoints_headers ();
1183 printf_filtered ("Num ");
1185 printf_filtered ("Type ");
1187 printf_filtered ("Disp ");
1189 printf_filtered ("Enb ");
1193 printf_filtered ("Address ");
1196 printf_filtered ("What\n");
1198 annotate_breakpoints_table ();
1202 Here's the new version:
1205 nr_printable_breakpoints = @dots{};
1208 ui_out_table_begin (ui, 6, nr_printable_breakpoints, "BreakpointTable");
1210 ui_out_table_begin (ui, 5, nr_printable_breakpoints, "BreakpointTable");
1212 if (nr_printable_breakpoints > 0)
1213 annotate_breakpoints_headers ();
1214 if (nr_printable_breakpoints > 0)
1216 ui_out_table_header (uiout, 3, ui_left, "number", "Num"); /* 1 */
1217 if (nr_printable_breakpoints > 0)
1219 ui_out_table_header (uiout, 14, ui_left, "type", "Type"); /* 2 */
1220 if (nr_printable_breakpoints > 0)
1222 ui_out_table_header (uiout, 4, ui_left, "disp", "Disp"); /* 3 */
1223 if (nr_printable_breakpoints > 0)
1225 ui_out_table_header (uiout, 3, ui_left, "enabled", "Enb"); /* 4 */
1228 if (nr_printable_breakpoints > 0)
1230 if (TARGET_ADDR_BIT <= 32)
1231 ui_out_table_header (uiout, 10, ui_left, "addr", "Address");/* 5 */
1233 ui_out_table_header (uiout, 18, ui_left, "addr", "Address");/* 5 */
1235 if (nr_printable_breakpoints > 0)
1237 ui_out_table_header (uiout, 40, ui_noalign, "what", "What"); /* 6 */
1238 ui_out_table_body (uiout);
1239 if (nr_printable_breakpoints > 0)
1240 annotate_breakpoints_table ();
1243 This example, from the @code{print_one_breakpoint} function, shows how
1244 to produce the actual data for the table whose structure was defined
1245 in the above example. The original code was:
1250 printf_filtered ("%-3d ", b->number);
1252 if ((int)b->type > (sizeof(bptypes)/sizeof(bptypes[0]))
1253 || ((int) b->type != bptypes[(int) b->type].type))
1254 internal_error ("bptypes table does not describe type #%d.",
1256 printf_filtered ("%-14s ", bptypes[(int)b->type].description);
1258 printf_filtered ("%-4s ", bpdisps[(int)b->disposition]);
1260 printf_filtered ("%-3c ", bpenables[(int)b->enable]);
1264 This is the new version:
1268 ui_out_tuple_begin (uiout, "bkpt");
1270 ui_out_field_int (uiout, "number", b->number);
1272 if (((int) b->type > (sizeof (bptypes) / sizeof (bptypes[0])))
1273 || ((int) b->type != bptypes[(int) b->type].type))
1274 internal_error ("bptypes table does not describe type #%d.",
1276 ui_out_field_string (uiout, "type", bptypes[(int)b->type].description);
1278 ui_out_field_string (uiout, "disp", bpdisps[(int)b->disposition]);
1280 ui_out_field_fmt (uiout, "enabled", "%c", bpenables[(int)b->enable]);
1284 This example, also from @code{print_one_breakpoint}, shows how to
1285 produce a complicated output field using the @code{print_expression}
1286 functions which requires a stream to be passed. It also shows how to
1287 automate stream destruction with cleanups. The original code was:
1291 print_expression (b->exp, gdb_stdout);
1297 struct ui_stream *stb = ui_out_stream_new (uiout);
1298 struct cleanup *old_chain = make_cleanup_ui_out_stream_delete (stb);
1301 print_expression (b->exp, stb->stream);
1302 ui_out_field_stream (uiout, "what", local_stream);
1305 This example, also from @code{print_one_breakpoint}, shows how to use
1306 @code{ui_out_text} and @code{ui_out_field_string}. The original code
1311 if (b->dll_pathname == NULL)
1312 printf_filtered ("<any library> ");
1314 printf_filtered ("library \"%s\" ", b->dll_pathname);
1321 if (b->dll_pathname == NULL)
1323 ui_out_field_string (uiout, "what", "<any library>");
1324 ui_out_spaces (uiout, 1);
1328 ui_out_text (uiout, "library \"");
1329 ui_out_field_string (uiout, "what", b->dll_pathname);
1330 ui_out_text (uiout, "\" ");
1334 The following example from @code{print_one_breakpoint} shows how to
1335 use @code{ui_out_field_int} and @code{ui_out_spaces}. The original
1340 if (b->forked_inferior_pid != 0)
1341 printf_filtered ("process %d ", b->forked_inferior_pid);
1348 if (b->forked_inferior_pid != 0)
1350 ui_out_text (uiout, "process ");
1351 ui_out_field_int (uiout, "what", b->forked_inferior_pid);
1352 ui_out_spaces (uiout, 1);
1356 Here's an example of using @code{ui_out_field_string}. The original
1361 if (b->exec_pathname != NULL)
1362 printf_filtered ("program \"%s\" ", b->exec_pathname);
1369 if (b->exec_pathname != NULL)
1371 ui_out_text (uiout, "program \"");
1372 ui_out_field_string (uiout, "what", b->exec_pathname);
1373 ui_out_text (uiout, "\" ");
1377 Finally, here's an example of printing an address. The original code:
1381 printf_filtered ("%s ",
1382 local_hex_string_custom ((unsigned long) b->address, "08l"));
1389 ui_out_field_core_addr (uiout, "Address", b->address);
1393 @section Console Printing
1402 @cindex @code{libgdb}
1403 @code{libgdb} 1.0 was an abortive project of years ago. The theory was
1404 to provide an API to @value{GDBN}'s functionality.
1407 @cindex @code{libgdb}
1408 @code{libgdb} 2.0 is an ongoing effort to update @value{GDBN} so that is
1409 better able to support graphical and other environments.
1411 Since @code{libgdb} development is on-going, its architecture is still
1412 evolving. The following components have so far been identified:
1416 Observer - @file{gdb-events.h}.
1418 Builder - @file{ui-out.h}
1420 Event Loop - @file{event-loop.h}
1422 Library - @file{gdb.h}
1425 The model that ties these components together is described below.
1427 @section The @code{libgdb} Model
1429 A client of @code{libgdb} interacts with the library in two ways.
1433 As an observer (using @file{gdb-events}) receiving notifications from
1434 @code{libgdb} of any internal state changes (break point changes, run
1437 As a client querying @code{libgdb} (using the @file{ui-out} builder) to
1438 obtain various status values from @value{GDBN}.
1441 Since @code{libgdb} could have multiple clients (e.g. a GUI supporting
1442 the existing @value{GDBN} CLI), those clients must co-operate when
1443 controlling @code{libgdb}. In particular, a client must ensure that
1444 @code{libgdb} is idle (i.e. no other client is using @code{libgdb})
1445 before responding to a @file{gdb-event} by making a query.
1447 @section CLI support
1449 At present @value{GDBN}'s CLI is very much entangled in with the core of
1450 @code{libgdb}. Consequently, a client wishing to include the CLI in
1451 their interface needs to carefully co-ordinate its own and the CLI's
1454 It is suggested that the client set @code{libgdb} up to be bi-modal
1455 (alternate between CLI and client query modes). The notes below sketch
1460 The client registers itself as an observer of @code{libgdb}.
1462 The client create and install @code{cli-out} builder using its own
1463 versions of the @code{ui-file} @code{gdb_stderr}, @code{gdb_stdtarg} and
1464 @code{gdb_stdout} streams.
1466 The client creates a separate custom @code{ui-out} builder that is only
1467 used while making direct queries to @code{libgdb}.
1470 When the client receives input intended for the CLI, it simply passes it
1471 along. Since the @code{cli-out} builder is installed by default, all
1472 the CLI output in response to that command is routed (pronounced rooted)
1473 through to the client controlled @code{gdb_stdout} et.@: al.@: streams.
1474 At the same time, the client is kept abreast of internal changes by
1475 virtue of being a @code{libgdb} observer.
1477 The only restriction on the client is that it must wait until
1478 @code{libgdb} becomes idle before initiating any queries (using the
1479 client's custom builder).
1481 @section @code{libgdb} components
1483 @subheading Observer - @file{gdb-events.h}
1484 @file{gdb-events} provides the client with a very raw mechanism that can
1485 be used to implement an observer. At present it only allows for one
1486 observer and that observer must, internally, handle the need to delay
1487 the processing of any event notifications until after @code{libgdb} has
1488 finished the current command.
1490 @subheading Builder - @file{ui-out.h}
1491 @file{ui-out} provides the infrastructure necessary for a client to
1492 create a builder. That builder is then passed down to @code{libgdb}
1493 when doing any queries.
1495 @subheading Event Loop - @file{event-loop.h}
1496 @c There could be an entire section on the event-loop
1497 @file{event-loop}, currently non-re-entrant, provides a simple event
1498 loop. A client would need to either plug its self into this loop or,
1499 implement a new event-loop that GDB would use.
1501 The event-loop will eventually be made re-entrant. This is so that
1502 @value{GDBN} can better handle the problem of some commands blocking
1503 instead of returning.
1505 @subheading Library - @file{gdb.h}
1506 @file{libgdb} is the most obvious component of this system. It provides
1507 the query interface. Each function is parameterized by a @code{ui-out}
1508 builder. The result of the query is constructed using that builder
1509 before the query function returns.
1511 @node Symbol Handling
1513 @chapter Symbol Handling
1515 Symbols are a key part of @value{GDBN}'s operation. Symbols include variables,
1516 functions, and types.
1518 @section Symbol Reading
1520 @cindex symbol reading
1521 @cindex reading of symbols
1522 @cindex symbol files
1523 @value{GDBN} reads symbols from @dfn{symbol files}. The usual symbol
1524 file is the file containing the program which @value{GDBN} is
1525 debugging. @value{GDBN} can be directed to use a different file for
1526 symbols (with the @samp{symbol-file} command), and it can also read
1527 more symbols via the @samp{add-file} and @samp{load} commands, or while
1528 reading symbols from shared libraries.
1530 @findex find_sym_fns
1531 Symbol files are initially opened by code in @file{symfile.c} using
1532 the BFD library (@pxref{Support Libraries}). BFD identifies the type
1533 of the file by examining its header. @code{find_sym_fns} then uses
1534 this identification to locate a set of symbol-reading functions.
1536 @findex add_symtab_fns
1537 @cindex @code{sym_fns} structure
1538 @cindex adding a symbol-reading module
1539 Symbol-reading modules identify themselves to @value{GDBN} by calling
1540 @code{add_symtab_fns} during their module initialization. The argument
1541 to @code{add_symtab_fns} is a @code{struct sym_fns} which contains the
1542 name (or name prefix) of the symbol format, the length of the prefix,
1543 and pointers to four functions. These functions are called at various
1544 times to process symbol files whose identification matches the specified
1547 The functions supplied by each module are:
1550 @item @var{xyz}_symfile_init(struct sym_fns *sf)
1552 @cindex secondary symbol file
1553 Called from @code{symbol_file_add} when we are about to read a new
1554 symbol file. This function should clean up any internal state (possibly
1555 resulting from half-read previous files, for example) and prepare to
1556 read a new symbol file. Note that the symbol file which we are reading
1557 might be a new ``main'' symbol file, or might be a secondary symbol file
1558 whose symbols are being added to the existing symbol table.
1560 The argument to @code{@var{xyz}_symfile_init} is a newly allocated
1561 @code{struct sym_fns} whose @code{bfd} field contains the BFD for the
1562 new symbol file being read. Its @code{private} field has been zeroed,
1563 and can be modified as desired. Typically, a struct of private
1564 information will be @code{malloc}'d, and a pointer to it will be placed
1565 in the @code{private} field.
1567 There is no result from @code{@var{xyz}_symfile_init}, but it can call
1568 @code{error} if it detects an unavoidable problem.
1570 @item @var{xyz}_new_init()
1572 Called from @code{symbol_file_add} when discarding existing symbols.
1573 This function needs only handle the symbol-reading module's internal
1574 state; the symbol table data structures visible to the rest of
1575 @value{GDBN} will be discarded by @code{symbol_file_add}. It has no
1576 arguments and no result. It may be called after
1577 @code{@var{xyz}_symfile_init}, if a new symbol table is being read, or
1578 may be called alone if all symbols are simply being discarded.
1580 @item @var{xyz}_symfile_read(struct sym_fns *sf, CORE_ADDR addr, int mainline)
1582 Called from @code{symbol_file_add} to actually read the symbols from a
1583 symbol-file into a set of psymtabs or symtabs.
1585 @code{sf} points to the @code{struct sym_fns} originally passed to
1586 @code{@var{xyz}_sym_init} for possible initialization. @code{addr} is
1587 the offset between the file's specified start address and its true
1588 address in memory. @code{mainline} is 1 if this is the main symbol
1589 table being read, and 0 if a secondary symbol file (e.g. shared library
1590 or dynamically loaded file) is being read.@refill
1593 In addition, if a symbol-reading module creates psymtabs when
1594 @var{xyz}_symfile_read is called, these psymtabs will contain a pointer
1595 to a function @code{@var{xyz}_psymtab_to_symtab}, which can be called
1596 from any point in the @value{GDBN} symbol-handling code.
1599 @item @var{xyz}_psymtab_to_symtab (struct partial_symtab *pst)
1601 Called from @code{psymtab_to_symtab} (or the @code{PSYMTAB_TO_SYMTAB} macro) if
1602 the psymtab has not already been read in and had its @code{pst->symtab}
1603 pointer set. The argument is the psymtab to be fleshed-out into a
1604 symtab. Upon return, @code{pst->readin} should have been set to 1, and
1605 @code{pst->symtab} should contain a pointer to the new corresponding symtab, or
1606 zero if there were no symbols in that part of the symbol file.
1609 @section Partial Symbol Tables
1611 @value{GDBN} has three types of symbol tables:
1614 @cindex full symbol table
1617 Full symbol tables (@dfn{symtabs}). These contain the main
1618 information about symbols and addresses.
1622 Partial symbol tables (@dfn{psymtabs}). These contain enough
1623 information to know when to read the corresponding part of the full
1626 @cindex minimal symbol table
1629 Minimal symbol tables (@dfn{msymtabs}). These contain information
1630 gleaned from non-debugging symbols.
1633 @cindex partial symbol table
1634 This section describes partial symbol tables.
1636 A psymtab is constructed by doing a very quick pass over an executable
1637 file's debugging information. Small amounts of information are
1638 extracted---enough to identify which parts of the symbol table will
1639 need to be re-read and fully digested later, when the user needs the
1640 information. The speed of this pass causes @value{GDBN} to start up very
1641 quickly. Later, as the detailed rereading occurs, it occurs in small
1642 pieces, at various times, and the delay therefrom is mostly invisible to
1644 @c (@xref{Symbol Reading}.)
1646 The symbols that show up in a file's psymtab should be, roughly, those
1647 visible to the debugger's user when the program is not running code from
1648 that file. These include external symbols and types, static symbols and
1649 types, and @code{enum} values declared at file scope.
1651 The psymtab also contains the range of instruction addresses that the
1652 full symbol table would represent.
1654 @cindex finding a symbol
1655 @cindex symbol lookup
1656 The idea is that there are only two ways for the user (or much of the
1657 code in the debugger) to reference a symbol:
1660 @findex find_pc_function
1661 @findex find_pc_line
1663 By its address (e.g. execution stops at some address which is inside a
1664 function in this file). The address will be noticed to be in the
1665 range of this psymtab, and the full symtab will be read in.
1666 @code{find_pc_function}, @code{find_pc_line}, and other
1667 @code{find_pc_@dots{}} functions handle this.
1669 @cindex lookup_symbol
1672 (e.g. the user asks to print a variable, or set a breakpoint on a
1673 function). Global names and file-scope names will be found in the
1674 psymtab, which will cause the symtab to be pulled in. Local names will
1675 have to be qualified by a global name, or a file-scope name, in which
1676 case we will have already read in the symtab as we evaluated the
1677 qualifier. Or, a local symbol can be referenced when we are ``in'' a
1678 local scope, in which case the first case applies. @code{lookup_symbol}
1679 does most of the work here.
1682 The only reason that psymtabs exist is to cause a symtab to be read in
1683 at the right moment. Any symbol that can be elided from a psymtab,
1684 while still causing that to happen, should not appear in it. Since
1685 psymtabs don't have the idea of scope, you can't put local symbols in
1686 them anyway. Psymtabs don't have the idea of the type of a symbol,
1687 either, so types need not appear, unless they will be referenced by
1690 It is a bug for @value{GDBN} to behave one way when only a psymtab has
1691 been read, and another way if the corresponding symtab has been read
1692 in. Such bugs are typically caused by a psymtab that does not contain
1693 all the visible symbols, or which has the wrong instruction address
1696 The psymtab for a particular section of a symbol file (objfile) could be
1697 thrown away after the symtab has been read in. The symtab should always
1698 be searched before the psymtab, so the psymtab will never be used (in a
1699 bug-free environment). Currently, psymtabs are allocated on an obstack,
1700 and all the psymbols themselves are allocated in a pair of large arrays
1701 on an obstack, so there is little to be gained by trying to free them
1702 unless you want to do a lot more work.
1706 @unnumberedsubsec Fundamental Types (e.g., @code{FT_VOID}, @code{FT_BOOLEAN}).
1708 @cindex fundamental types
1709 These are the fundamental types that @value{GDBN} uses internally. Fundamental
1710 types from the various debugging formats (stabs, ELF, etc) are mapped
1711 into one of these. They are basically a union of all fundamental types
1712 that @value{GDBN} knows about for all the languages that @value{GDBN}
1715 @unnumberedsubsec Type Codes (e.g., @code{TYPE_CODE_PTR}, @code{TYPE_CODE_ARRAY}).
1718 Each time @value{GDBN} builds an internal type, it marks it with one
1719 of these types. The type may be a fundamental type, such as
1720 @code{TYPE_CODE_INT}, or a derived type, such as @code{TYPE_CODE_PTR}
1721 which is a pointer to another type. Typically, several @code{FT_*}
1722 types map to one @code{TYPE_CODE_*} type, and are distinguished by
1723 other members of the type struct, such as whether the type is signed
1724 or unsigned, and how many bits it uses.
1726 @unnumberedsubsec Builtin Types (e.g., @code{builtin_type_void}, @code{builtin_type_char}).
1728 These are instances of type structs that roughly correspond to
1729 fundamental types and are created as global types for @value{GDBN} to
1730 use for various ugly historical reasons. We eventually want to
1731 eliminate these. Note for example that @code{builtin_type_int}
1732 initialized in @file{gdbtypes.c} is basically the same as a
1733 @code{TYPE_CODE_INT} type that is initialized in @file{c-lang.c} for
1734 an @code{FT_INTEGER} fundamental type. The difference is that the
1735 @code{builtin_type} is not associated with any particular objfile, and
1736 only one instance exists, while @file{c-lang.c} builds as many
1737 @code{TYPE_CODE_INT} types as needed, with each one associated with
1738 some particular objfile.
1740 @section Object File Formats
1741 @cindex object file formats
1745 @cindex @code{a.out} format
1746 The @code{a.out} format is the original file format for Unix. It
1747 consists of three sections: @code{text}, @code{data}, and @code{bss},
1748 which are for program code, initialized data, and uninitialized data,
1751 The @code{a.out} format is so simple that it doesn't have any reserved
1752 place for debugging information. (Hey, the original Unix hackers used
1753 @samp{adb}, which is a machine-language debugger!) The only debugging
1754 format for @code{a.out} is stabs, which is encoded as a set of normal
1755 symbols with distinctive attributes.
1757 The basic @code{a.out} reader is in @file{dbxread.c}.
1762 The COFF format was introduced with System V Release 3 (SVR3) Unix.
1763 COFF files may have multiple sections, each prefixed by a header. The
1764 number of sections is limited.
1766 The COFF specification includes support for debugging. Although this
1767 was a step forward, the debugging information was woefully limited. For
1768 instance, it was not possible to represent code that came from an
1771 The COFF reader is in @file{coffread.c}.
1775 @cindex ECOFF format
1776 ECOFF is an extended COFF originally introduced for Mips and Alpha
1779 The basic ECOFF reader is in @file{mipsread.c}.
1783 @cindex XCOFF format
1784 The IBM RS/6000 running AIX uses an object file format called XCOFF.
1785 The COFF sections, symbols, and line numbers are used, but debugging
1786 symbols are @code{dbx}-style stabs whose strings are located in the
1787 @code{.debug} section (rather than the string table). For more
1788 information, see @ref{Top,,,stabs,The Stabs Debugging Format}.
1790 The shared library scheme has a clean interface for figuring out what
1791 shared libraries are in use, but the catch is that everything which
1792 refers to addresses (symbol tables and breakpoints at least) needs to be
1793 relocated for both shared libraries and the main executable. At least
1794 using the standard mechanism this can only be done once the program has
1795 been run (or the core file has been read).
1799 @cindex PE-COFF format
1800 Windows 95 and NT use the PE (@dfn{Portable Executable}) format for their
1801 executables. PE is basically COFF with additional headers.
1803 While BFD includes special PE support, @value{GDBN} needs only the basic
1809 The ELF format came with System V Release 4 (SVR4) Unix. ELF is similar
1810 to COFF in being organized into a number of sections, but it removes
1811 many of COFF's limitations.
1813 The basic ELF reader is in @file{elfread.c}.
1818 SOM is HP's object file and debug format (not to be confused with IBM's
1819 SOM, which is a cross-language ABI).
1821 The SOM reader is in @file{hpread.c}.
1823 @subsection Other File Formats
1825 @cindex Netware Loadable Module format
1826 Other file formats that have been supported by @value{GDBN} include Netware
1827 Loadable Modules (@file{nlmread.c}).
1829 @section Debugging File Formats
1831 This section describes characteristics of debugging information that
1832 are independent of the object file format.
1836 @cindex stabs debugging info
1837 @code{stabs} started out as special symbols within the @code{a.out}
1838 format. Since then, it has been encapsulated into other file
1839 formats, such as COFF and ELF.
1841 While @file{dbxread.c} does some of the basic stab processing,
1842 including for encapsulated versions, @file{stabsread.c} does
1847 @cindex COFF debugging info
1848 The basic COFF definition includes debugging information. The level
1849 of support is minimal and non-extensible, and is not often used.
1851 @subsection Mips debug (Third Eye)
1853 @cindex ECOFF debugging info
1854 ECOFF includes a definition of a special debug format.
1856 The file @file{mdebugread.c} implements reading for this format.
1860 @cindex DWARF 1 debugging info
1861 DWARF 1 is a debugging format that was originally designed to be
1862 used with ELF in SVR4 systems.
1867 @c If defined, these are the producer strings in a DWARF 1 file. All of
1868 @c these have reasonable defaults already.
1870 The DWARF 1 reader is in @file{dwarfread.c}.
1874 @cindex DWARF 2 debugging info
1875 DWARF 2 is an improved but incompatible version of DWARF 1.
1877 The DWARF 2 reader is in @file{dwarf2read.c}.
1881 @cindex SOM debugging info
1882 Like COFF, the SOM definition includes debugging information.
1884 @section Adding a New Symbol Reader to @value{GDBN}
1886 @cindex adding debugging info reader
1887 If you are using an existing object file format (@code{a.out}, COFF, ELF, etc),
1888 there is probably little to be done.
1890 If you need to add a new object file format, you must first add it to
1891 BFD. This is beyond the scope of this document.
1893 You must then arrange for the BFD code to provide access to the
1894 debugging symbols. Generally @value{GDBN} will have to call swapping routines
1895 from BFD and a few other BFD internal routines to locate the debugging
1896 information. As much as possible, @value{GDBN} should not depend on the BFD
1897 internal data structures.
1899 For some targets (e.g., COFF), there is a special transfer vector used
1900 to call swapping routines, since the external data structures on various
1901 platforms have different sizes and layouts. Specialized routines that
1902 will only ever be implemented by one object file format may be called
1903 directly. This interface should be described in a file
1904 @file{bfd/lib@var{xyz}.h}, which is included by @value{GDBN}.
1907 @node Language Support
1909 @chapter Language Support
1911 @cindex language support
1912 @value{GDBN}'s language support is mainly driven by the symbol reader,
1913 although it is possible for the user to set the source language
1916 @value{GDBN} chooses the source language by looking at the extension
1917 of the file recorded in the debug info; @file{.c} means C, @file{.f}
1918 means Fortran, etc. It may also use a special-purpose language
1919 identifier if the debug format supports it, like with DWARF.
1921 @section Adding a Source Language to @value{GDBN}
1923 @cindex adding source language
1924 To add other languages to @value{GDBN}'s expression parser, follow the
1928 @item Create the expression parser.
1930 @cindex expression parser
1931 This should reside in a file @file{@var{lang}-exp.y}. Routines for
1932 building parsed expressions into a @code{union exp_element} list are in
1935 @cindex language parser
1936 Since we can't depend upon everyone having Bison, and YACC produces
1937 parsers that define a bunch of global names, the following lines
1938 @strong{must} be included at the top of the YACC parser, to prevent the
1939 various parsers from defining the same global names:
1942 #define yyparse @var{lang}_parse
1943 #define yylex @var{lang}_lex
1944 #define yyerror @var{lang}_error
1945 #define yylval @var{lang}_lval
1946 #define yychar @var{lang}_char
1947 #define yydebug @var{lang}_debug
1948 #define yypact @var{lang}_pact
1949 #define yyr1 @var{lang}_r1
1950 #define yyr2 @var{lang}_r2
1951 #define yydef @var{lang}_def
1952 #define yychk @var{lang}_chk
1953 #define yypgo @var{lang}_pgo
1954 #define yyact @var{lang}_act
1955 #define yyexca @var{lang}_exca
1956 #define yyerrflag @var{lang}_errflag
1957 #define yynerrs @var{lang}_nerrs
1960 At the bottom of your parser, define a @code{struct language_defn} and
1961 initialize it with the right values for your language. Define an
1962 @code{initialize_@var{lang}} routine and have it call
1963 @samp{add_language(@var{lang}_language_defn)} to tell the rest of @value{GDBN}
1964 that your language exists. You'll need some other supporting variables
1965 and functions, which will be used via pointers from your
1966 @code{@var{lang}_language_defn}. See the declaration of @code{struct
1967 language_defn} in @file{language.h}, and the other @file{*-exp.y} files,
1968 for more information.
1970 @item Add any evaluation routines, if necessary
1972 @cindex expression evaluation routines
1973 @findex evaluate_subexp
1974 @findex prefixify_subexp
1975 @findex length_of_subexp
1976 If you need new opcodes (that represent the operations of the language),
1977 add them to the enumerated type in @file{expression.h}. Add support
1978 code for these operations in the @code{evaluate_subexp} function
1979 defined in the file @file{eval.c}. Add cases
1980 for new opcodes in two functions from @file{parse.c}:
1981 @code{prefixify_subexp} and @code{length_of_subexp}. These compute
1982 the number of @code{exp_element}s that a given operation takes up.
1984 @item Update some existing code
1986 Add an enumerated identifier for your language to the enumerated type
1987 @code{enum language} in @file{defs.h}.
1989 Update the routines in @file{language.c} so your language is included.
1990 These routines include type predicates and such, which (in some cases)
1991 are language dependent. If your language does not appear in the switch
1992 statement, an error is reported.
1994 @vindex current_language
1995 Also included in @file{language.c} is the code that updates the variable
1996 @code{current_language}, and the routines that translate the
1997 @code{language_@var{lang}} enumerated identifier into a printable
2000 @findex _initialize_language
2001 Update the function @code{_initialize_language} to include your
2002 language. This function picks the default language upon startup, so is
2003 dependent upon which languages that @value{GDBN} is built for.
2005 @findex allocate_symtab
2006 Update @code{allocate_symtab} in @file{symfile.c} and/or symbol-reading
2007 code so that the language of each symtab (source file) is set properly.
2008 This is used to determine the language to use at each stack frame level.
2009 Currently, the language is set based upon the extension of the source
2010 file. If the language can be better inferred from the symbol
2011 information, please set the language of the symtab in the symbol-reading
2014 @findex print_subexp
2015 @findex op_print_tab
2016 Add helper code to @code{print_subexp} (in @file{expprint.c}) to handle any new
2017 expression opcodes you have added to @file{expression.h}. Also, add the
2018 printed representations of your operators to @code{op_print_tab}.
2020 @item Add a place of call
2023 Add a call to @code{@var{lang}_parse()} and @code{@var{lang}_error} in
2024 @code{parse_exp_1} (defined in @file{parse.c}).
2026 @item Use macros to trim code
2028 @cindex trimming language-dependent code
2029 The user has the option of building @value{GDBN} for some or all of the
2030 languages. If the user decides to build @value{GDBN} for the language
2031 @var{lang}, then every file dependent on @file{language.h} will have the
2032 macro @code{_LANG_@var{lang}} defined in it. Use @code{#ifdef}s to
2033 leave out large routines that the user won't need if he or she is not
2034 using your language.
2036 Note that you do not need to do this in your YACC parser, since if @value{GDBN}
2037 is not build for @var{lang}, then @file{@var{lang}-exp.tab.o} (the
2038 compiled form of your parser) is not linked into @value{GDBN} at all.
2040 See the file @file{configure.in} for how @value{GDBN} is configured
2041 for different languages.
2043 @item Edit @file{Makefile.in}
2045 Add dependencies in @file{Makefile.in}. Make sure you update the macro
2046 variables such as @code{HFILES} and @code{OBJS}, otherwise your code may
2047 not get linked in, or, worse yet, it may not get @code{tar}red into the
2052 @node Host Definition
2054 @chapter Host Definition
2056 With the advent of Autoconf, it's rarely necessary to have host
2057 definition machinery anymore. The following information is provided,
2058 mainly, as an historical reference.
2060 @section Adding a New Host
2062 @cindex adding a new host
2063 @cindex host, adding
2064 @value{GDBN}'s host configuration support normally happens via Autoconf.
2065 New host-specific definitions should not be needed. Older hosts
2066 @value{GDBN} still use the host-specific definitions and files listed
2067 below, but these mostly exist for historical reasons, and will
2068 eventually disappear.
2071 @item gdb/config/@var{arch}/@var{xyz}.mh
2072 This file once contained both host and native configuration information
2073 (@pxref{Native Debugging}) for the machine @var{xyz}. The host
2074 configuration information is now handed by Autoconf.
2076 Host configuration information included a definition of
2077 @code{XM_FILE=xm-@var{xyz}.h} and possibly definitions for @code{CC},
2078 @code{SYSV_DEFINE}, @code{XM_CFLAGS}, @code{XM_ADD_FILES},
2079 @code{XM_CLIBS}, @code{XM_CDEPS}, etc.; see @file{Makefile.in}.
2081 New host only configurations do not need this file.
2083 @item gdb/config/@var{arch}/xm-@var{xyz}.h
2084 This file once contained definitions and includes required when hosting
2085 gdb on machine @var{xyz}. Those definitions and includes are now
2086 handled by Autoconf.
2088 New host and native configurations do not need this file.
2090 @emph{Maintainer's note: Some hosts continue to use the @file{xm-xyz.h}
2091 file to define the macros @var{HOST_FLOAT_FORMAT},
2092 @var{HOST_DOUBLE_FORMAT} and @var{HOST_LONG_DOUBLE_FORMAT}. That code
2093 also needs to be replaced with either an Autoconf or run-time test.}
2097 @subheading Generic Host Support Files
2099 @cindex generic host support
2100 There are some ``generic'' versions of routines that can be used by
2101 various systems. These can be customized in various ways by macros
2102 defined in your @file{xm-@var{xyz}.h} file. If these routines work for
2103 the @var{xyz} host, you can just include the generic file's name (with
2104 @samp{.o}, not @samp{.c}) in @code{XDEPFILES}.
2106 Otherwise, if your machine needs custom support routines, you will need
2107 to write routines that perform the same functions as the generic file.
2108 Put them into @code{@var{xyz}-xdep.c}, and put @code{@var{xyz}-xdep.o}
2109 into @code{XDEPFILES}.
2112 @cindex remote debugging support
2113 @cindex serial line support
2115 This contains serial line support for Unix systems. This is always
2116 included, via the makefile variable @code{SER_HARDWIRE}; override this
2117 variable in the @file{.mh} file to avoid it.
2120 This contains serial line support for 32-bit programs running under DOS,
2121 using the DJGPP (a.k.a.@: GO32) execution environment.
2123 @cindex TCP remote support
2125 This contains generic TCP support using sockets.
2128 @section Host Conditionals
2130 When @value{GDBN} is configured and compiled, various macros are
2131 defined or left undefined, to control compilation based on the
2132 attributes of the host system. These macros and their meanings (or if
2133 the meaning is not documented here, then one of the source files where
2134 they are used is indicated) are:
2137 @item @value{GDBN}INIT_FILENAME
2138 The default name of @value{GDBN}'s initialization file (normally
2142 This macro is deprecated.
2145 Define this if your system does not have a @code{<sys/file.h>}.
2147 @item SIGWINCH_HANDLER
2148 If your host defines @code{SIGWINCH}, you can define this to be the name
2149 of a function to be called if @code{SIGWINCH} is received.
2151 @item SIGWINCH_HANDLER_BODY
2152 Define this to expand into code that will define the function named by
2153 the expansion of @code{SIGWINCH_HANDLER}.
2155 @item ALIGN_STACK_ON_STARTUP
2156 @cindex stack alignment
2157 Define this if your system is of a sort that will crash in
2158 @code{tgetent} if the stack happens not to be longword-aligned when
2159 @code{main} is called. This is a rare situation, but is known to occur
2160 on several different types of systems.
2162 @item CRLF_SOURCE_FILES
2163 @cindex DOS text files
2164 Define this if host files use @code{\r\n} rather than @code{\n} as a
2165 line terminator. This will cause source file listings to omit @code{\r}
2166 characters when printing and it will allow @code{\r\n} line endings of files
2167 which are ``sourced'' by gdb. It must be possible to open files in binary
2168 mode using @code{O_BINARY} or, for fopen, @code{"rb"}.
2170 @item DEFAULT_PROMPT
2172 The default value of the prompt string (normally @code{"(gdb) "}).
2175 @cindex terminal device
2176 The name of the generic TTY device, defaults to @code{"/dev/tty"}.
2178 @item FCLOSE_PROVIDED
2179 Define this if the system declares @code{fclose} in the headers included
2180 in @code{defs.h}. This isn't needed unless your compiler is unusually
2184 Define this if binary files are opened the same way as text files.
2186 @item GETENV_PROVIDED
2187 Define this if the system declares @code{getenv} in its headers included
2188 in @code{defs.h}. This isn't needed unless your compiler is unusually
2193 In some cases, use the system call @code{mmap} for reading symbol
2194 tables. For some machines this allows for sharing and quick updates.
2197 Define this if the host system has @code{termio.h}.
2204 Values for host-side constants.
2207 Substitute for isatty, if not available.
2210 This is the longest integer type available on the host. If not defined,
2211 it will default to @code{long long} or @code{long}, depending on
2212 @code{CC_HAS_LONG_LONG}.
2214 @item CC_HAS_LONG_LONG
2215 @cindex @code{long long} data type
2216 Define this if the host C compiler supports @code{long long}. This is set
2217 by the @code{configure} script.
2219 @item PRINTF_HAS_LONG_LONG
2220 Define this if the host can handle printing of long long integers via
2221 the printf format conversion specifier @code{ll}. This is set by the
2222 @code{configure} script.
2224 @item HAVE_LONG_DOUBLE
2225 Define this if the host C compiler supports @code{long double}. This is
2226 set by the @code{configure} script.
2228 @item PRINTF_HAS_LONG_DOUBLE
2229 Define this if the host can handle printing of long double float-point
2230 numbers via the printf format conversion specifier @code{Lg}. This is
2231 set by the @code{configure} script.
2233 @item SCANF_HAS_LONG_DOUBLE
2234 Define this if the host can handle the parsing of long double
2235 float-point numbers via the scanf format conversion specifier
2236 @code{Lg}. This is set by the @code{configure} script.
2238 @item LSEEK_NOT_LINEAR
2239 Define this if @code{lseek (n)} does not necessarily move to byte number
2240 @code{n} in the file. This is only used when reading source files. It
2241 is normally faster to define @code{CRLF_SOURCE_FILES} when possible.
2244 This macro is used as the argument to @code{lseek} (or, most commonly,
2245 @code{bfd_seek}). FIXME, should be replaced by SEEK_SET instead,
2246 which is the POSIX equivalent.
2248 @item MMAP_BASE_ADDRESS
2249 When using HAVE_MMAP, the first mapping should go at this address.
2251 @item MMAP_INCREMENT
2252 when using HAVE_MMAP, this is the increment between mappings.
2255 If defined, this should be one or more tokens, such as @code{volatile},
2256 that can be used in both the declaration and definition of functions to
2257 indicate that they never return. The default is already set correctly
2258 if compiling with GCC. This will almost never need to be defined.
2261 If defined, this should be one or more tokens, such as
2262 @code{__attribute__ ((noreturn))}, that can be used in the declarations
2263 of functions to indicate that they never return. The default is already
2264 set correctly if compiling with GCC. This will almost never need to be
2269 @value{GDBN} will use the @code{mmalloc} library for memory allocation
2270 for symbol reading if this symbol is defined. Be careful defining it
2271 since there are systems on which @code{mmalloc} does not work for some
2272 reason. One example is the DECstation, where its RPC library can't
2273 cope with our redefinition of @code{malloc} to call @code{mmalloc}.
2274 When defining @code{USE_MMALLOC}, you will also have to set
2275 @code{MMALLOC} in the Makefile, to point to the @code{mmalloc} library. This
2276 define is set when you configure with @samp{--with-mmalloc}.
2280 Define this if you are using @code{mmalloc}, but don't want the overhead
2281 of checking the heap with @code{mmcheck}. Note that on some systems,
2282 the C runtime makes calls to @code{malloc} prior to calling @code{main}, and if
2283 @code{free} is ever called with these pointers after calling
2284 @code{mmcheck} to enable checking, a memory corruption abort is certain
2285 to occur. These systems can still use @code{mmalloc}, but must define
2289 Define this to 1 if the C runtime allocates memory prior to
2290 @code{mmcheck} being called, but that memory is never freed so we don't
2291 have to worry about it triggering a memory corruption abort. The
2292 default is 0, which means that @code{mmcheck} will only install the heap
2293 checking functions if there has not yet been any memory allocation
2294 calls, and if it fails to install the functions, @value{GDBN} will issue a
2295 warning. This is currently defined if you configure using
2296 @samp{--with-mmalloc}.
2298 @item NO_SIGINTERRUPT
2299 @findex siginterrupt
2300 Define this to indicate that @code{siginterrupt} is not available.
2304 Define these to appropriate value for the system @code{lseek}, if not already
2308 This is the signal for stopping @value{GDBN}. Defaults to
2309 @code{SIGTSTP}. (Only redefined for the Convex.)
2312 Define this if the interior's tty should be opened with the @code{O_NOCTTY}
2313 flag. (FIXME: This should be a native-only flag, but @file{inflow.c} is
2317 Means that System V (prior to SVR4) include files are in use. (FIXME:
2318 This symbol is abused in @file{infrun.c}, @file{regex.c}, and
2319 @file{utils.c} for other things, at the moment.)
2322 Define this to help placate @code{lint} in some situations.
2325 Define this to override the defaults of @code{__volatile__} or
2330 @node Target Architecture Definition
2332 @chapter Target Architecture Definition
2334 @cindex target architecture definition
2335 @value{GDBN}'s target architecture defines what sort of
2336 machine-language programs @value{GDBN} can work with, and how it works
2339 The target architecture object is implemented as the C structure
2340 @code{struct gdbarch *}. The structure, and its methods, are generated
2341 using the Bourne shell script @file{gdbarch.sh}.
2343 @section Operating System ABI Variant Handling
2344 @cindex OS ABI variants
2346 @value{GDBN} provides a mechanism for handling variations in OS
2347 ABIs. An OS ABI variant may have influence over any number of
2348 variables in the target architecture definition. There are two major
2349 components in the OS ABI mechanism: sniffers and handlers.
2351 A @dfn{sniffer} examines a file matching a BFD architecture/flavour pair
2352 (the architecture may be wildcarded) in an attempt to determine the
2353 OS ABI of that file. Sniffers with a wildcarded architecture are considered
2354 to be @dfn{generic}, while sniffers for a specific architecture are
2355 considered to be @dfn{specific}. A match from a specific sniffer
2356 overrides a match from a generic sniffer. Multiple sniffers for an
2357 architecture/flavour may exist, in order to differentiate between two
2358 different operating systems which use the same basic file format. The
2359 OS ABI framework provides a generic sniffer for ELF-format files which
2360 examines the @code{EI_OSABI} field of the ELF header, as well as note
2361 sections known to be used by several operating systems.
2363 @cindex fine-tuning @code{gdbarch} structure
2364 A @dfn{handler} is used to fine-tune the @code{gdbarch} structure for the
2365 selected OS ABI. There may be only one handler for a given OS ABI
2366 for each BFD architecture.
2368 The following OS ABI variants are defined in @file{osabi.h}:
2372 @findex GDB_OSABI_UNKNOWN
2373 @item GDB_OSABI_UNKNOWN
2374 The ABI of the inferior is unknown. The default @code{gdbarch}
2375 settings for the architecture will be used.
2377 @findex GDB_OSABI_SVR4
2378 @item GDB_OSABI_SVR4
2379 UNIX System V Release 4
2381 @findex GDB_OSABI_HURD
2382 @item GDB_OSABI_HURD
2383 GNU using the Hurd kernel
2385 @findex GDB_OSABI_SOLARIS
2386 @item GDB_OSABI_SOLARIS
2389 @findex GDB_OSABI_OSF1
2390 @item GDB_OSABI_OSF1
2391 OSF/1, including Digital UNIX and Compaq Tru64 UNIX
2393 @findex GDB_OSABI_LINUX
2394 @item GDB_OSABI_LINUX
2395 GNU using the Linux kernel
2397 @findex GDB_OSABI_FREEBSD_AOUT
2398 @item GDB_OSABI_FREEBSD_AOUT
2399 FreeBSD using the a.out executable format
2401 @findex GDB_OSABI_FREEBSD_ELF
2402 @item GDB_OSABI_FREEBSD_ELF
2403 FreeBSD using the ELF executable format
2405 @findex GDB_OSABI_NETBSD_AOUT
2406 @item GDB_OSABI_NETBSD_AOUT
2407 NetBSD using the a.out executable format
2409 @findex GDB_OSABI_NETBSD_ELF
2410 @item GDB_OSABI_NETBSD_ELF
2411 NetBSD using the ELF executable format
2413 @findex GDB_OSABI_WINCE
2414 @item GDB_OSABI_WINCE
2417 @findex GDB_OSABI_GO32
2418 @item GDB_OSABI_GO32
2421 @findex GDB_OSABI_NETWARE
2422 @item GDB_OSABI_NETWARE
2425 @findex GDB_OSABI_ARM_EABI_V1
2426 @item GDB_OSABI_ARM_EABI_V1
2427 ARM Embedded ABI version 1
2429 @findex GDB_OSABI_ARM_EABI_V2
2430 @item GDB_OSABI_ARM_EABI_V2
2431 ARM Embedded ABI version 2
2433 @findex GDB_OSABI_ARM_APCS
2434 @item GDB_OSABI_ARM_APCS
2435 Generic ARM Procedure Call Standard
2439 Here are the functions that make up the OS ABI framework:
2441 @deftypefun const char *gdbarch_osabi_name (enum gdb_osabi @var{osabi})
2442 Return the name of the OS ABI corresponding to @var{osabi}.
2445 @deftypefun void gdbarch_register_osabi (enum bfd_architecture @var{arch}, unsigned long @var{machine}, enum gdb_osabi @var{osabi}, void (*@var{init_osabi})(struct gdbarch_info @var{info}, struct gdbarch *@var{gdbarch}))
2446 Register the OS ABI handler specified by @var{init_osabi} for the
2447 architecture, machine type and OS ABI specified by @var{arch},
2448 @var{machine} and @var{osabi}. In most cases, a value of zero for the
2449 machine type, which implies the architecture's default machine type,
2453 @deftypefun void gdbarch_register_osabi_sniffer (enum bfd_architecture @var{arch}, enum bfd_flavour @var{flavour}, enum gdb_osabi (*@var{sniffer})(bfd *@var{abfd}))
2454 Register the OS ABI file sniffer specified by @var{sniffer} for the
2455 BFD architecture/flavour pair specified by @var{arch} and @var{flavour}.
2456 If @var{arch} is @code{bfd_arch_unknown}, the sniffer is considered to
2457 be generic, and is allowed to examine @var{flavour}-flavoured files for
2461 @deftypefun enum gdb_osabi gdbarch_lookup_osabi (bfd *@var{abfd})
2462 Examine the file described by @var{abfd} to determine its OS ABI.
2463 The value @code{GDB_OSABI_UNKNOWN} is returned if the OS ABI cannot
2467 @deftypefun void gdbarch_init_osabi (struct gdbarch info @var{info}, struct gdbarch *@var{gdbarch}, enum gdb_osabi @var{osabi})
2468 Invoke the OS ABI handler corresponding to @var{osabi} to fine-tune the
2469 @code{gdbarch} structure specified by @var{gdbarch}. If a handler
2470 corresponding to @var{osabi} has not been registered for @var{gdbarch}'s
2471 architecture, a warning will be issued and the debugging session will continue
2472 with the defaults already established for @var{gdbarch}.
2475 @section Registers and Memory
2477 @value{GDBN}'s model of the target machine is rather simple.
2478 @value{GDBN} assumes the machine includes a bank of registers and a
2479 block of memory. Each register may have a different size.
2481 @value{GDBN} does not have a magical way to match up with the
2482 compiler's idea of which registers are which; however, it is critical
2483 that they do match up accurately. The only way to make this work is
2484 to get accurate information about the order that the compiler uses,
2485 and to reflect that in the @code{REGISTER_NAME} and related macros.
2487 @value{GDBN} can handle big-endian, little-endian, and bi-endian architectures.
2489 @section Pointers Are Not Always Addresses
2490 @cindex pointer representation
2491 @cindex address representation
2492 @cindex word-addressed machines
2493 @cindex separate data and code address spaces
2494 @cindex spaces, separate data and code address
2495 @cindex address spaces, separate data and code
2496 @cindex code pointers, word-addressed
2497 @cindex converting between pointers and addresses
2498 @cindex D10V addresses
2500 On almost all 32-bit architectures, the representation of a pointer is
2501 indistinguishable from the representation of some fixed-length number
2502 whose value is the byte address of the object pointed to. On such
2503 machines, the words ``pointer'' and ``address'' can be used interchangeably.
2504 However, architectures with smaller word sizes are often cramped for
2505 address space, so they may choose a pointer representation that breaks this
2506 identity, and allows a larger code address space.
2508 For example, the Renesas D10V is a 16-bit VLIW processor whose
2509 instructions are 32 bits long@footnote{Some D10V instructions are
2510 actually pairs of 16-bit sub-instructions. However, since you can't
2511 jump into the middle of such a pair, code addresses can only refer to
2512 full 32 bit instructions, which is what matters in this explanation.}.
2513 If the D10V used ordinary byte addresses to refer to code locations,
2514 then the processor would only be able to address 64kb of instructions.
2515 However, since instructions must be aligned on four-byte boundaries, the
2516 low two bits of any valid instruction's byte address are always
2517 zero---byte addresses waste two bits. So instead of byte addresses,
2518 the D10V uses word addresses---byte addresses shifted right two bits---to
2519 refer to code. Thus, the D10V can use 16-bit words to address 256kb of
2522 However, this means that code pointers and data pointers have different
2523 forms on the D10V. The 16-bit word @code{0xC020} refers to byte address
2524 @code{0xC020} when used as a data address, but refers to byte address
2525 @code{0x30080} when used as a code address.
2527 (The D10V also uses separate code and data address spaces, which also
2528 affects the correspondence between pointers and addresses, but we're
2529 going to ignore that here; this example is already too long.)
2531 To cope with architectures like this---the D10V is not the only
2532 one!---@value{GDBN} tries to distinguish between @dfn{addresses}, which are
2533 byte numbers, and @dfn{pointers}, which are the target's representation
2534 of an address of a particular type of data. In the example above,
2535 @code{0xC020} is the pointer, which refers to one of the addresses
2536 @code{0xC020} or @code{0x30080}, depending on the type imposed upon it.
2537 @value{GDBN} provides functions for turning a pointer into an address
2538 and vice versa, in the appropriate way for the current architecture.
2540 Unfortunately, since addresses and pointers are identical on almost all
2541 processors, this distinction tends to bit-rot pretty quickly. Thus,
2542 each time you port @value{GDBN} to an architecture which does
2543 distinguish between pointers and addresses, you'll probably need to
2544 clean up some architecture-independent code.
2546 Here are functions which convert between pointers and addresses:
2548 @deftypefun CORE_ADDR extract_typed_address (void *@var{buf}, struct type *@var{type})
2549 Treat the bytes at @var{buf} as a pointer or reference of type
2550 @var{type}, and return the address it represents, in a manner
2551 appropriate for the current architecture. This yields an address
2552 @value{GDBN} can use to read target memory, disassemble, etc. Note that
2553 @var{buf} refers to a buffer in @value{GDBN}'s memory, not the
2556 For example, if the current architecture is the Intel x86, this function
2557 extracts a little-endian integer of the appropriate length from
2558 @var{buf} and returns it. However, if the current architecture is the
2559 D10V, this function will return a 16-bit integer extracted from
2560 @var{buf}, multiplied by four if @var{type} is a pointer to a function.
2562 If @var{type} is not a pointer or reference type, then this function
2563 will signal an internal error.
2566 @deftypefun CORE_ADDR store_typed_address (void *@var{buf}, struct type *@var{type}, CORE_ADDR @var{addr})
2567 Store the address @var{addr} in @var{buf}, in the proper format for a
2568 pointer of type @var{type} in the current architecture. Note that
2569 @var{buf} refers to a buffer in @value{GDBN}'s memory, not the
2572 For example, if the current architecture is the Intel x86, this function
2573 stores @var{addr} unmodified as a little-endian integer of the
2574 appropriate length in @var{buf}. However, if the current architecture
2575 is the D10V, this function divides @var{addr} by four if @var{type} is
2576 a pointer to a function, and then stores it in @var{buf}.
2578 If @var{type} is not a pointer or reference type, then this function
2579 will signal an internal error.
2582 @deftypefun CORE_ADDR value_as_address (struct value *@var{val})
2583 Assuming that @var{val} is a pointer, return the address it represents,
2584 as appropriate for the current architecture.
2586 This function actually works on integral values, as well as pointers.
2587 For pointers, it performs architecture-specific conversions as
2588 described above for @code{extract_typed_address}.
2591 @deftypefun CORE_ADDR value_from_pointer (struct type *@var{type}, CORE_ADDR @var{addr})
2592 Create and return a value representing a pointer of type @var{type} to
2593 the address @var{addr}, as appropriate for the current architecture.
2594 This function performs architecture-specific conversions as described
2595 above for @code{store_typed_address}.
2598 Here are some macros which architectures can define to indicate the
2599 relationship between pointers and addresses. These have default
2600 definitions, appropriate for architectures on which all pointers are
2601 simple unsigned byte addresses.
2603 @deftypefn {Target Macro} CORE_ADDR POINTER_TO_ADDRESS (struct type *@var{type}, char *@var{buf})
2604 Assume that @var{buf} holds a pointer of type @var{type}, in the
2605 appropriate format for the current architecture. Return the byte
2606 address the pointer refers to.
2608 This function may safely assume that @var{type} is either a pointer or a
2609 C@t{++} reference type.
2612 @deftypefn {Target Macro} void ADDRESS_TO_POINTER (struct type *@var{type}, char *@var{buf}, CORE_ADDR @var{addr})
2613 Store in @var{buf} a pointer of type @var{type} representing the address
2614 @var{addr}, in the appropriate format for the current architecture.
2616 This function may safely assume that @var{type} is either a pointer or a
2617 C@t{++} reference type.
2620 @section Address Classes
2621 @cindex address classes
2622 @cindex DW_AT_byte_size
2623 @cindex DW_AT_address_class
2625 Sometimes information about different kinds of addresses is available
2626 via the debug information. For example, some programming environments
2627 define addresses of several different sizes. If the debug information
2628 distinguishes these kinds of address classes through either the size
2629 info (e.g, @code{DW_AT_byte_size} in @w{DWARF 2}) or through an explicit
2630 address class attribute (e.g, @code{DW_AT_address_class} in @w{DWARF 2}), the
2631 following macros should be defined in order to disambiguate these
2632 types within @value{GDBN} as well as provide the added information to
2633 a @value{GDBN} user when printing type expressions.
2635 @deftypefn {Target Macro} int ADDRESS_CLASS_TYPE_FLAGS (int @var{byte_size}, int @var{dwarf2_addr_class})
2636 Returns the type flags needed to construct a pointer type whose size
2637 is @var{byte_size} and whose address class is @var{dwarf2_addr_class}.
2638 This function is normally called from within a symbol reader. See
2639 @file{dwarf2read.c}.
2642 @deftypefn {Target Macro} char *ADDRESS_CLASS_TYPE_FLAGS_TO_NAME (int @var{type_flags})
2643 Given the type flags representing an address class qualifier, return
2646 @deftypefn {Target Macro} int ADDRESS_CLASS_NAME_to_TYPE_FLAGS (int @var{name}, int *var{type_flags_ptr})
2647 Given an address qualifier name, set the @code{int} refererenced by @var{type_flags_ptr} to the type flags
2648 for that address class qualifier.
2651 Since the need for address classes is rather rare, none of
2652 the address class macros defined by default. Predicate
2653 macros are provided to detect when they are defined.
2655 Consider a hypothetical architecture in which addresses are normally
2656 32-bits wide, but 16-bit addresses are also supported. Furthermore,
2657 suppose that the @w{DWARF 2} information for this architecture simply
2658 uses a @code{DW_AT_byte_size} value of 2 to indicate the use of one
2659 of these "short" pointers. The following functions could be defined
2660 to implement the address class macros:
2663 somearch_address_class_type_flags (int byte_size,
2664 int dwarf2_addr_class)
2667 return TYPE_FLAG_ADDRESS_CLASS_1;
2673 somearch_address_class_type_flags_to_name (int type_flags)
2675 if (type_flags & TYPE_FLAG_ADDRESS_CLASS_1)
2682 somearch_address_class_name_to_type_flags (char *name,
2683 int *type_flags_ptr)
2685 if (strcmp (name, "short") == 0)
2687 *type_flags_ptr = TYPE_FLAG_ADDRESS_CLASS_1;
2695 The qualifier @code{@@short} is used in @value{GDBN}'s type expressions
2696 to indicate the presence of one of these "short" pointers. E.g, if
2697 the debug information indicates that @code{short_ptr_var} is one of these
2698 short pointers, @value{GDBN} might show the following behavior:
2701 (gdb) ptype short_ptr_var
2702 type = int * @@short
2706 @section Raw and Virtual Register Representations
2707 @cindex raw register representation
2708 @cindex virtual register representation
2709 @cindex representations, raw and virtual registers
2711 @emph{Maintainer note: This section is pretty much obsolete. The
2712 functionality described here has largely been replaced by
2713 pseudo-registers and the mechanisms described in @ref{Target
2714 Architecture Definition, , Using Different Register and Memory Data
2715 Representations}. See also @uref{http://www.gnu.org/software/gdb/bugs/,
2716 Bug Tracking Database} and
2717 @uref{http://sources.redhat.com/gdb/current/ari/, ARI Index} for more
2718 up-to-date information.}
2720 Some architectures use one representation for a value when it lives in a
2721 register, but use a different representation when it lives in memory.
2722 In @value{GDBN}'s terminology, the @dfn{raw} representation is the one used in
2723 the target registers, and the @dfn{virtual} representation is the one
2724 used in memory, and within @value{GDBN} @code{struct value} objects.
2726 @emph{Maintainer note: Notice that the same mechanism is being used to
2727 both convert a register to a @code{struct value} and alternative
2730 For almost all data types on almost all architectures, the virtual and
2731 raw representations are identical, and no special handling is needed.
2732 However, they do occasionally differ. For example:
2736 The x86 architecture supports an 80-bit @code{long double} type. However, when
2737 we store those values in memory, they occupy twelve bytes: the
2738 floating-point number occupies the first ten, and the final two bytes
2739 are unused. This keeps the values aligned on four-byte boundaries,
2740 allowing more efficient access. Thus, the x86 80-bit floating-point
2741 type is the raw representation, and the twelve-byte loosely-packed
2742 arrangement is the virtual representation.
2745 Some 64-bit MIPS targets present 32-bit registers to @value{GDBN} as 64-bit
2746 registers, with garbage in their upper bits. @value{GDBN} ignores the top 32
2747 bits. Thus, the 64-bit form, with garbage in the upper 32 bits, is the
2748 raw representation, and the trimmed 32-bit representation is the
2749 virtual representation.
2752 In general, the raw representation is determined by the architecture, or
2753 @value{GDBN}'s interface to the architecture, while the virtual representation
2754 can be chosen for @value{GDBN}'s convenience. @value{GDBN}'s register file,
2755 @code{registers}, holds the register contents in raw format, and the
2756 @value{GDBN} remote protocol transmits register values in raw format.
2758 Your architecture may define the following macros to request
2759 conversions between the raw and virtual format:
2761 @deftypefn {Target Macro} int REGISTER_CONVERTIBLE (int @var{reg})
2762 Return non-zero if register number @var{reg}'s value needs different raw
2763 and virtual formats.
2765 You should not use @code{REGISTER_CONVERT_TO_VIRTUAL} for a register
2766 unless this macro returns a non-zero value for that register.
2769 @deftypefn {Target Macro} int DEPRECATED_REGISTER_RAW_SIZE (int @var{reg})
2770 The size of register number @var{reg}'s raw value. This is the number
2771 of bytes the register will occupy in @code{registers}, or in a @value{GDBN}
2772 remote protocol packet.
2775 @deftypefn {Target Macro} int DEPRECATED_REGISTER_VIRTUAL_SIZE (int @var{reg})
2776 The size of register number @var{reg}'s value, in its virtual format.
2777 This is the size a @code{struct value}'s buffer will have, holding that
2781 @deftypefn {Target Macro} struct type *DEPRECATED_REGISTER_VIRTUAL_TYPE (int @var{reg})
2782 This is the type of the virtual representation of register number
2783 @var{reg}. Note that there is no need for a macro giving a type for the
2784 register's raw form; once the register's value has been obtained, @value{GDBN}
2785 always uses the virtual form.
2788 @deftypefn {Target Macro} void REGISTER_CONVERT_TO_VIRTUAL (int @var{reg}, struct type *@var{type}, char *@var{from}, char *@var{to})
2789 Convert the value of register number @var{reg} to @var{type}, which
2790 should always be @code{DEPRECATED_REGISTER_VIRTUAL_TYPE (@var{reg})}. The buffer
2791 at @var{from} holds the register's value in raw format; the macro should
2792 convert the value to virtual format, and place it at @var{to}.
2794 Note that @code{REGISTER_CONVERT_TO_VIRTUAL} and
2795 @code{REGISTER_CONVERT_TO_RAW} take their @var{reg} and @var{type}
2796 arguments in different orders.
2798 You should only use @code{REGISTER_CONVERT_TO_VIRTUAL} with registers
2799 for which the @code{REGISTER_CONVERTIBLE} macro returns a non-zero
2803 @deftypefn {Target Macro} void REGISTER_CONVERT_TO_RAW (struct type *@var{type}, int @var{reg}, char *@var{from}, char *@var{to})
2804 Convert the value of register number @var{reg} to @var{type}, which
2805 should always be @code{DEPRECATED_REGISTER_VIRTUAL_TYPE (@var{reg})}. The buffer
2806 at @var{from} holds the register's value in raw format; the macro should
2807 convert the value to virtual format, and place it at @var{to}.
2809 Note that REGISTER_CONVERT_TO_VIRTUAL and REGISTER_CONVERT_TO_RAW take
2810 their @var{reg} and @var{type} arguments in different orders.
2814 @section Using Different Register and Memory Data Representations
2815 @cindex register representation
2816 @cindex memory representation
2817 @cindex representations, register and memory
2818 @cindex register data formats, converting
2819 @cindex @code{struct value}, converting register contents to
2821 @emph{Maintainer's note: The way GDB manipulates registers is undergoing
2822 significant change. Many of the macros and functions refered to in this
2823 section are likely to be subject to further revision. See
2824 @uref{http://sources.redhat.com/gdb/current/ari/, A.R. Index} and
2825 @uref{http://www.gnu.org/software/gdb/bugs, Bug Tracking Database} for
2826 further information. cagney/2002-05-06.}
2828 Some architectures can represent a data object in a register using a
2829 form that is different to the objects more normal memory representation.
2835 The Alpha architecture can represent 32 bit integer values in
2836 floating-point registers.
2839 The x86 architecture supports 80-bit floating-point registers. The
2840 @code{long double} data type occupies 96 bits in memory but only 80 bits
2841 when stored in a register.
2845 In general, the register representation of a data type is determined by
2846 the architecture, or @value{GDBN}'s interface to the architecture, while
2847 the memory representation is determined by the Application Binary
2850 For almost all data types on almost all architectures, the two
2851 representations are identical, and no special handling is needed.
2852 However, they do occasionally differ. Your architecture may define the
2853 following macros to request conversions between the register and memory
2854 representations of a data type:
2856 @deftypefn {Target Macro} int CONVERT_REGISTER_P (int @var{reg})
2857 Return non-zero if the representation of a data value stored in this
2858 register may be different to the representation of that same data value
2859 when stored in memory.
2861 When non-zero, the macros @code{REGISTER_TO_VALUE} and
2862 @code{VALUE_TO_REGISTER} are used to perform any necessary conversion.
2865 @deftypefn {Target Macro} void REGISTER_TO_VALUE (int @var{reg}, struct type *@var{type}, char *@var{from}, char *@var{to})
2866 Convert the value of register number @var{reg} to a data object of type
2867 @var{type}. The buffer at @var{from} holds the register's value in raw
2868 format; the converted value should be placed in the buffer at @var{to}.
2870 Note that @code{REGISTER_TO_VALUE} and @code{VALUE_TO_REGISTER} take
2871 their @var{reg} and @var{type} arguments in different orders.
2873 You should only use @code{REGISTER_TO_VALUE} with registers for which
2874 the @code{CONVERT_REGISTER_P} macro returns a non-zero value.
2877 @deftypefn {Target Macro} void VALUE_TO_REGISTER (struct type *@var{type}, int @var{reg}, char *@var{from}, char *@var{to})
2878 Convert a data value of type @var{type} to register number @var{reg}'
2881 Note that @code{REGISTER_TO_VALUE} and @code{VALUE_TO_REGISTER} take
2882 their @var{reg} and @var{type} arguments in different orders.
2884 You should only use @code{VALUE_TO_REGISTER} with registers for which
2885 the @code{CONVERT_REGISTER_P} macro returns a non-zero value.
2888 @deftypefn {Target Macro} void REGISTER_CONVERT_TO_TYPE (int @var{regnum}, struct type *@var{type}, char *@var{buf})
2889 See @file{mips-tdep.c}. It does not do what you want.
2893 @section Frame Interpretation
2895 @section Inferior Call Setup
2897 @section Compiler Characteristics
2899 @section Target Conditionals
2901 This section describes the macros that you can use to define the target
2906 @item ADDR_BITS_REMOVE (addr)
2907 @findex ADDR_BITS_REMOVE
2908 If a raw machine instruction address includes any bits that are not
2909 really part of the address, then define this macro to expand into an
2910 expression that zeroes those bits in @var{addr}. This is only used for
2911 addresses of instructions, and even then not in all contexts.
2913 For example, the two low-order bits of the PC on the Hewlett-Packard PA
2914 2.0 architecture contain the privilege level of the corresponding
2915 instruction. Since instructions must always be aligned on four-byte
2916 boundaries, the processor masks out these bits to generate the actual
2917 address of the instruction. ADDR_BITS_REMOVE should filter out these
2918 bits with an expression such as @code{((addr) & ~3)}.
2920 @item ADDRESS_CLASS_NAME_TO_TYPE_FLAGS (@var{name}, @var{type_flags_ptr})
2921 @findex ADDRESS_CLASS_NAME_TO_TYPE_FLAGS
2922 If @var{name} is a valid address class qualifier name, set the @code{int}
2923 referenced by @var{type_flags_ptr} to the mask representing the qualifier
2924 and return 1. If @var{name} is not a valid address class qualifier name,
2927 The value for @var{type_flags_ptr} should be one of
2928 @code{TYPE_FLAG_ADDRESS_CLASS_1}, @code{TYPE_FLAG_ADDRESS_CLASS_2}, or
2929 possibly some combination of these values or'd together.
2930 @xref{Target Architecture Definition, , Address Classes}.
2932 @item ADDRESS_CLASS_NAME_TO_TYPE_FLAGS_P ()
2933 @findex ADDRESS_CLASS_NAME_TO_TYPE_FLAGS_P
2934 Predicate which indicates whether @code{ADDRESS_CLASS_NAME_TO_TYPE_FLAGS}
2937 @item ADDRESS_CLASS_TYPE_FLAGS (@var{byte_size}, @var{dwarf2_addr_class})
2938 @findex ADDRESS_CLASS_TYPE_FLAGS (@var{byte_size}, @var{dwarf2_addr_class})
2939 Given a pointers byte size (as described by the debug information) and
2940 the possible @code{DW_AT_address_class} value, return the type flags
2941 used by @value{GDBN} to represent this address class. The value
2942 returned should be one of @code{TYPE_FLAG_ADDRESS_CLASS_1},
2943 @code{TYPE_FLAG_ADDRESS_CLASS_2}, or possibly some combination of these
2944 values or'd together.
2945 @xref{Target Architecture Definition, , Address Classes}.
2947 @item ADDRESS_CLASS_TYPE_FLAGS_P ()
2948 @findex ADDRESS_CLASS_TYPE_FLAGS_P
2949 Predicate which indicates whether @code{ADDRESS_CLASS_TYPE_FLAGS} has
2952 @item ADDRESS_CLASS_TYPE_FLAGS_TO_NAME (@var{type_flags})
2953 @findex ADDRESS_CLASS_TYPE_FLAGS_TO_NAME
2954 Return the name of the address class qualifier associated with the type
2955 flags given by @var{type_flags}.
2957 @item ADDRESS_CLASS_TYPE_FLAGS_TO_NAME_P ()
2958 @findex ADDRESS_CLASS_TYPE_FLAGS_TO_NAME_P
2959 Predicate which indicates whether @code{ADDRESS_CLASS_TYPE_FLAGS_TO_NAME} has
2961 @xref{Target Architecture Definition, , Address Classes}.
2963 @item ADDRESS_TO_POINTER (@var{type}, @var{buf}, @var{addr})
2964 @findex ADDRESS_TO_POINTER
2965 Store in @var{buf} a pointer of type @var{type} representing the address
2966 @var{addr}, in the appropriate format for the current architecture.
2967 This macro may safely assume that @var{type} is either a pointer or a
2968 C@t{++} reference type.
2969 @xref{Target Architecture Definition, , Pointers Are Not Always Addresses}.
2971 @item BELIEVE_PCC_PROMOTION
2972 @findex BELIEVE_PCC_PROMOTION
2973 Define if the compiler promotes a @code{short} or @code{char}
2974 parameter to an @code{int}, but still reports the parameter as its
2975 original type, rather than the promoted type.
2977 @item BELIEVE_PCC_PROMOTION_TYPE
2978 @findex BELIEVE_PCC_PROMOTION_TYPE
2979 Define this if @value{GDBN} should believe the type of a @code{short}
2980 argument when compiled by @code{pcc}, but look within a full int space to get
2981 its value. Only defined for Sun-3 at present.
2983 @item BITS_BIG_ENDIAN
2984 @findex BITS_BIG_ENDIAN
2985 Define this if the numbering of bits in the targets does @strong{not} match the
2986 endianness of the target byte order. A value of 1 means that the bits
2987 are numbered in a big-endian bit order, 0 means little-endian.
2991 This is the character array initializer for the bit pattern to put into
2992 memory where a breakpoint is set. Although it's common to use a trap
2993 instruction for a breakpoint, it's not required; for instance, the bit
2994 pattern could be an invalid instruction. The breakpoint must be no
2995 longer than the shortest instruction of the architecture.
2997 @code{BREAKPOINT} has been deprecated in favor of
2998 @code{BREAKPOINT_FROM_PC}.
3000 @item BIG_BREAKPOINT
3001 @itemx LITTLE_BREAKPOINT
3002 @findex LITTLE_BREAKPOINT
3003 @findex BIG_BREAKPOINT
3004 Similar to BREAKPOINT, but used for bi-endian targets.
3006 @code{BIG_BREAKPOINT} and @code{LITTLE_BREAKPOINT} have been deprecated in
3007 favor of @code{BREAKPOINT_FROM_PC}.
3009 @item DEPRECATED_REMOTE_BREAKPOINT
3010 @itemx DEPRECATED_LITTLE_REMOTE_BREAKPOINT
3011 @itemx DEPRECATED_BIG_REMOTE_BREAKPOINT
3012 @findex DEPRECATED_BIG_REMOTE_BREAKPOINT
3013 @findex DEPRECATED_LITTLE_REMOTE_BREAKPOINT
3014 @findex DEPRECATED_REMOTE_BREAKPOINT
3015 Specify the breakpoint instruction sequence for a remote target.
3016 @code{DEPRECATED_REMOTE_BREAKPOINT},
3017 @code{DEPRECATED_BIG_REMOTE_BREAKPOINT} and
3018 @code{DEPRECATED_LITTLE_REMOTE_BREAKPOINT} have been deprecated in
3019 favor of @code{BREAKPOINT_FROM_PC} (@pxref{BREAKPOINT_FROM_PC}).
3021 @item BREAKPOINT_FROM_PC (@var{pcptr}, @var{lenptr})
3022 @findex BREAKPOINT_FROM_PC
3023 @anchor{BREAKPOINT_FROM_PC} Use the program counter to determine the
3024 contents and size of a breakpoint instruction. It returns a pointer to
3025 a string of bytes that encode a breakpoint instruction, stores the
3026 length of the string to @code{*@var{lenptr}}, and adjusts the program
3027 counter (if necessary) to point to the actual memory location where the
3028 breakpoint should be inserted.
3030 Although it is common to use a trap instruction for a breakpoint, it's
3031 not required; for instance, the bit pattern could be an invalid
3032 instruction. The breakpoint must be no longer than the shortest
3033 instruction of the architecture.
3035 Replaces all the other @var{BREAKPOINT} macros.
3037 @item MEMORY_INSERT_BREAKPOINT (@var{addr}, @var{contents_cache})
3038 @itemx MEMORY_REMOVE_BREAKPOINT (@var{addr}, @var{contents_cache})
3039 @findex MEMORY_REMOVE_BREAKPOINT
3040 @findex MEMORY_INSERT_BREAKPOINT
3041 Insert or remove memory based breakpoints. Reasonable defaults
3042 (@code{default_memory_insert_breakpoint} and
3043 @code{default_memory_remove_breakpoint} respectively) have been
3044 provided so that it is not necessary to define these for most
3045 architectures. Architectures which may want to define
3046 @code{MEMORY_INSERT_BREAKPOINT} and @code{MEMORY_REMOVE_BREAKPOINT} will
3047 likely have instructions that are oddly sized or are not stored in a
3048 conventional manner.
3050 It may also be desirable (from an efficiency standpoint) to define
3051 custom breakpoint insertion and removal routines if
3052 @code{BREAKPOINT_FROM_PC} needs to read the target's memory for some
3055 @item ADJUST_BREAKPOINT_ADDRESS (@var{address})
3056 @findex ADJUST_BREAKPOINT_ADDRESS
3057 @cindex breakpoint address adjusted
3058 Given an address at which a breakpoint is desired, return a breakpoint
3059 address adjusted to account for architectural constraints on
3060 breakpoint placement. This method is not needed by most targets.
3062 The FR-V target (see @file{frv-tdep.c}) requires this method.
3063 The FR-V is a VLIW architecture in which a number of RISC-like
3064 instructions are grouped (packed) together into an aggregate
3065 instruction or instruction bundle. When the processor executes
3066 one of these bundles, the component instructions are executed
3069 In the course of optimization, the compiler may group instructions
3070 from distinct source statements into the same bundle. The line number
3071 information associated with one of the latter statements will likely
3072 refer to some instruction other than the first one in the bundle. So,
3073 if the user attempts to place a breakpoint on one of these latter
3074 statements, @value{GDBN} must be careful to @emph{not} place the break
3075 instruction on any instruction other than the first one in the bundle.
3076 (Remember though that the instructions within a bundle execute
3077 in parallel, so the @emph{first} instruction is the instruction
3078 at the lowest address and has nothing to do with execution order.)
3080 The FR-V's @code{ADJUST_BREAKPOINT_ADDRESS} method will adjust a
3081 breakpoint's address by scanning backwards for the beginning of
3082 the bundle, returning the address of the bundle.
3084 Since the adjustment of a breakpoint may significantly alter a user's
3085 expectation, @value{GDBN} prints a warning when an adjusted breakpoint
3086 is initially set and each time that that breakpoint is hit.
3088 @item DEPRECATED_CALL_DUMMY_WORDS
3089 @findex DEPRECATED_CALL_DUMMY_WORDS
3090 Pointer to an array of @code{LONGEST} words of data containing
3091 host-byte-ordered @code{DEPRECATED_REGISTER_SIZE} sized values that
3092 partially specify the sequence of instructions needed for an inferior
3095 Should be deprecated in favor of a macro that uses target-byte-ordered
3098 This method has been replaced by @code{push_dummy_code}
3099 (@pxref{push_dummy_code}).
3101 @item DEPRECATED_SIZEOF_CALL_DUMMY_WORDS
3102 @findex DEPRECATED_SIZEOF_CALL_DUMMY_WORDS
3103 The size of @code{DEPRECATED_CALL_DUMMY_WORDS}. This must return a
3104 positive value. See also @code{DEPRECATED_CALL_DUMMY_LENGTH}.
3106 This method has been replaced by @code{push_dummy_code}
3107 (@pxref{push_dummy_code}).
3111 A static initializer for @code{DEPRECATED_CALL_DUMMY_WORDS}.
3114 This method has been replaced by @code{push_dummy_code}
3115 (@pxref{push_dummy_code}).
3117 @item CALL_DUMMY_LOCATION
3118 @findex CALL_DUMMY_LOCATION
3119 See the file @file{inferior.h}.
3121 This method has been replaced by @code{push_dummy_code}
3122 (@pxref{push_dummy_code}).
3124 @item DEPRECATED_CALL_DUMMY_STACK_ADJUST
3125 @findex DEPRECATED_CALL_DUMMY_STACK_ADJUST
3126 Stack adjustment needed when performing an inferior function call. This
3127 function is no longer needed. @xref{push_dummy_call}, which can handle
3128 all alignment directly.
3130 @item CANNOT_FETCH_REGISTER (@var{regno})
3131 @findex CANNOT_FETCH_REGISTER
3132 A C expression that should be nonzero if @var{regno} cannot be fetched
3133 from an inferior process. This is only relevant if
3134 @code{FETCH_INFERIOR_REGISTERS} is not defined.
3136 @item CANNOT_STORE_REGISTER (@var{regno})
3137 @findex CANNOT_STORE_REGISTER
3138 A C expression that should be nonzero if @var{regno} should not be
3139 written to the target. This is often the case for program counters,
3140 status words, and other special registers. If this is not defined,
3141 @value{GDBN} will assume that all registers may be written.
3143 @item DO_DEFERRED_STORES
3144 @itemx CLEAR_DEFERRED_STORES
3145 @findex CLEAR_DEFERRED_STORES
3146 @findex DO_DEFERRED_STORES
3147 Define this to execute any deferred stores of registers into the inferior,
3148 and to cancel any deferred stores.
3150 Currently only implemented correctly for native Sparc configurations?
3152 @item int CONVERT_REGISTER_P(@var{regnum})
3153 @findex CONVERT_REGISTER_P
3154 Return non-zero if register @var{regnum} can represent data values in a
3156 @xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}.
3158 @item DECR_PC_AFTER_BREAK
3159 @findex DECR_PC_AFTER_BREAK
3160 Define this to be the amount by which to decrement the PC after the
3161 program encounters a breakpoint. This is often the number of bytes in
3162 @code{BREAKPOINT}, though not always. For most targets this value will be 0.
3164 @item DECR_PC_AFTER_HW_BREAK
3165 @findex DECR_PC_AFTER_HW_BREAK
3166 Similarly, for hardware breakpoints.
3168 @item DISABLE_UNSETTABLE_BREAK (@var{addr})
3169 @findex DISABLE_UNSETTABLE_BREAK
3170 If defined, this should evaluate to 1 if @var{addr} is in a shared
3171 library in which breakpoints cannot be set and so should be disabled.
3173 @item PRINT_FLOAT_INFO()
3174 @findex PRINT_FLOAT_INFO
3175 If defined, then the @samp{info float} command will print information about
3176 the processor's floating point unit.
3178 @item print_registers_info (@var{gdbarch}, @var{frame}, @var{regnum}, @var{all})
3179 @findex print_registers_info
3180 If defined, pretty print the value of the register @var{regnum} for the
3181 specified @var{frame}. If the value of @var{regnum} is -1, pretty print
3182 either all registers (@var{all} is non zero) or a select subset of
3183 registers (@var{all} is zero).
3185 The default method prints one register per line, and if @var{all} is
3186 zero omits floating-point registers.
3188 @item PRINT_VECTOR_INFO()
3189 @findex PRINT_VECTOR_INFO
3190 If defined, then the @samp{info vector} command will call this function
3191 to print information about the processor's vector unit.
3193 By default, the @samp{info vector} command will print all vector
3194 registers (the register's type having the vector attribute).
3196 @item DWARF_REG_TO_REGNUM
3197 @findex DWARF_REG_TO_REGNUM
3198 Convert DWARF register number into @value{GDBN} regnum. If not defined,
3199 no conversion will be performed.
3201 @item DWARF2_REG_TO_REGNUM
3202 @findex DWARF2_REG_TO_REGNUM
3203 Convert DWARF2 register number into @value{GDBN} regnum. If not
3204 defined, no conversion will be performed.
3206 @item ECOFF_REG_TO_REGNUM
3207 @findex ECOFF_REG_TO_REGNUM
3208 Convert ECOFF register number into @value{GDBN} regnum. If not defined,
3209 no conversion will be performed.
3211 @item END_OF_TEXT_DEFAULT
3212 @findex END_OF_TEXT_DEFAULT
3213 This is an expression that should designate the end of the text section.
3216 @item EXTRACT_RETURN_VALUE(@var{type}, @var{regbuf}, @var{valbuf})
3217 @findex EXTRACT_RETURN_VALUE
3218 Define this to extract a function's return value of type @var{type} from
3219 the raw register state @var{regbuf} and copy that, in virtual format,
3222 @item EXTRACT_STRUCT_VALUE_ADDRESS(@var{regbuf})
3223 @findex EXTRACT_STRUCT_VALUE_ADDRESS
3224 When defined, extract from the array @var{regbuf} (containing the raw
3225 register state) the @code{CORE_ADDR} at which a function should return
3226 its structure value.
3228 If not defined, @code{EXTRACT_RETURN_VALUE} is used.
3230 @item EXTRACT_STRUCT_VALUE_ADDRESS_P()
3231 @findex EXTRACT_STRUCT_VALUE_ADDRESS_P
3232 Predicate for @code{EXTRACT_STRUCT_VALUE_ADDRESS}.
3234 @item DEPRECATED_FP_REGNUM
3235 @findex DEPRECATED_FP_REGNUM
3236 If the virtual frame pointer is kept in a register, then define this
3237 macro to be the number (greater than or equal to zero) of that register.
3239 This should only need to be defined if @code{DEPRECATED_TARGET_READ_FP}
3242 @item FRAMELESS_FUNCTION_INVOCATION(@var{fi})
3243 @findex FRAMELESS_FUNCTION_INVOCATION
3244 Define this to an expression that returns 1 if the function invocation
3245 represented by @var{fi} does not have a stack frame associated with it.
3248 @item frame_align (@var{address})
3249 @anchor{frame_align}
3251 Define this to adjust @var{address} so that it meets the alignment
3252 requirements for the start of a new stack frame. A stack frame's
3253 alignment requirements are typically stronger than a target processors
3254 stack alignment requirements (@pxref{DEPRECATED_STACK_ALIGN}).
3256 This function is used to ensure that, when creating a dummy frame, both
3257 the initial stack pointer and (if needed) the address of the return
3258 value are correctly aligned.
3260 Unlike @code{DEPRECATED_STACK_ALIGN}, this function always adjusts the
3261 address in the direction of stack growth.
3263 By default, no frame based stack alignment is performed.
3265 @item int frame_red_zone_size
3267 The number of bytes, beyond the innermost-stack-address, reserved by the
3268 @sc{abi}. A function is permitted to use this scratch area (instead of
3269 allocating extra stack space).
3271 When performing an inferior function call, to ensure that it does not
3272 modify this area, @value{GDBN} adjusts the innermost-stack-address by
3273 @var{frame_red_zone_size} bytes before pushing parameters onto the
3276 By default, zero bytes are allocated. The value must be aligned
3277 (@pxref{frame_align}).
3279 The @sc{amd64} (nee x86-64) @sc{abi} documentation refers to the
3280 @emph{red zone} when describing this scratch area.
3283 @item DEPRECATED_FRAME_CHAIN(@var{frame})
3284 @findex DEPRECATED_FRAME_CHAIN
3285 Given @var{frame}, return a pointer to the calling frame.
3287 @item DEPRECATED_FRAME_CHAIN_VALID(@var{chain}, @var{thisframe})
3288 @findex DEPRECATED_FRAME_CHAIN_VALID
3289 Define this to be an expression that returns zero if the given frame is an
3290 outermost frame, with no caller, and nonzero otherwise. Most normal
3291 situations can be handled without defining this macro, including @code{NULL}
3292 chain pointers, dummy frames, and frames whose PC values are inside the
3293 startup file (e.g.@: @file{crt0.o}), inside @code{main}, or inside
3296 @item DEPRECATED_FRAME_INIT_SAVED_REGS(@var{frame})
3297 @findex DEPRECATED_FRAME_INIT_SAVED_REGS
3298 See @file{frame.h}. Determines the address of all registers in the
3299 current stack frame storing each in @code{frame->saved_regs}. Space for
3300 @code{frame->saved_regs} shall be allocated by
3301 @code{DEPRECATED_FRAME_INIT_SAVED_REGS} using
3302 @code{frame_saved_regs_zalloc}.
3304 @code{FRAME_FIND_SAVED_REGS} is deprecated.
3306 @item FRAME_NUM_ARGS (@var{fi})
3307 @findex FRAME_NUM_ARGS
3308 For the frame described by @var{fi} return the number of arguments that
3309 are being passed. If the number of arguments is not known, return
3312 @item DEPRECATED_FRAME_SAVED_PC(@var{frame})
3313 @findex DEPRECATED_FRAME_SAVED_PC
3314 @anchor{DEPRECATED_FRAME_SAVED_PC} Given @var{frame}, return the pc
3315 saved there. This is the return address.
3317 This method is deprecated. @xref{unwind_pc}.
3319 @item CORE_ADDR unwind_pc (struct frame_info *@var{this_frame})
3321 @anchor{unwind_pc} Return the instruction address, in @var{this_frame}'s
3322 caller, at which execution will resume after @var{this_frame} returns.
3323 This is commonly refered to as the return address.
3325 The implementation, which must be frame agnostic (work with any frame),
3326 is typically no more than:
3330 frame_unwind_unsigned_register (this_frame, D10V_PC_REGNUM, &pc);
3331 return d10v_make_iaddr (pc);
3335 @xref{DEPRECATED_FRAME_SAVED_PC}, which this method replaces.
3337 @item CORE_ADDR unwind_sp (struct frame_info *@var{this_frame})
3339 @anchor{unwind_sp} Return the frame's inner most stack address. This is
3340 commonly refered to as the frame's @dfn{stack pointer}.
3342 The implementation, which must be frame agnostic (work with any frame),
3343 is typically no more than:
3347 frame_unwind_unsigned_register (this_frame, D10V_SP_REGNUM, &sp);
3348 return d10v_make_daddr (sp);
3352 @xref{TARGET_READ_SP}, which this method replaces.
3354 @item FUNCTION_EPILOGUE_SIZE
3355 @findex FUNCTION_EPILOGUE_SIZE
3356 For some COFF targets, the @code{x_sym.x_misc.x_fsize} field of the
3357 function end symbol is 0. For such targets, you must define
3358 @code{FUNCTION_EPILOGUE_SIZE} to expand into the standard size of a
3359 function's epilogue.
3361 @item FUNCTION_START_OFFSET
3362 @findex FUNCTION_START_OFFSET
3363 An integer, giving the offset in bytes from a function's address (as
3364 used in the values of symbols, function pointers, etc.), and the
3365 function's first genuine instruction.
3367 This is zero on almost all machines: the function's address is usually
3368 the address of its first instruction. However, on the VAX, for example,
3369 each function starts with two bytes containing a bitmask indicating
3370 which registers to save upon entry to the function. The VAX @code{call}
3371 instructions check this value, and save the appropriate registers
3372 automatically. Thus, since the offset from the function's address to
3373 its first instruction is two bytes, @code{FUNCTION_START_OFFSET} would
3376 @item GCC_COMPILED_FLAG_SYMBOL
3377 @itemx GCC2_COMPILED_FLAG_SYMBOL
3378 @findex GCC2_COMPILED_FLAG_SYMBOL
3379 @findex GCC_COMPILED_FLAG_SYMBOL
3380 If defined, these are the names of the symbols that @value{GDBN} will
3381 look for to detect that GCC compiled the file. The default symbols
3382 are @code{gcc_compiled.} and @code{gcc2_compiled.},
3383 respectively. (Currently only defined for the Delta 68.)
3385 @item @value{GDBN}_MULTI_ARCH
3386 @findex @value{GDBN}_MULTI_ARCH
3387 If defined and non-zero, enables support for multiple architectures
3388 within @value{GDBN}.
3390 This support can be enabled at two levels. At level one, only
3391 definitions for previously undefined macros are provided; at level two,
3392 a multi-arch definition of all architecture dependent macros will be
3395 @item @value{GDBN}_TARGET_IS_HPPA
3396 @findex @value{GDBN}_TARGET_IS_HPPA
3397 This determines whether horrible kludge code in @file{dbxread.c} and
3398 @file{partial-stab.h} is used to mangle multiple-symbol-table files from
3399 HPPA's. This should all be ripped out, and a scheme like @file{elfread.c}
3402 @item GET_LONGJMP_TARGET
3403 @findex GET_LONGJMP_TARGET
3404 For most machines, this is a target-dependent parameter. On the
3405 DECstation and the Iris, this is a native-dependent parameter, since
3406 the header file @file{setjmp.h} is needed to define it.
3408 This macro determines the target PC address that @code{longjmp} will jump to,
3409 assuming that we have just stopped at a @code{longjmp} breakpoint. It takes a
3410 @code{CORE_ADDR *} as argument, and stores the target PC value through this
3411 pointer. It examines the current state of the machine as needed.
3413 @item DEPRECATED_GET_SAVED_REGISTER
3414 @findex DEPRECATED_GET_SAVED_REGISTER
3415 Define this if you need to supply your own definition for the function
3416 @code{DEPRECATED_GET_SAVED_REGISTER}.
3418 @item DEPRECATED_IBM6000_TARGET
3419 @findex DEPRECATED_IBM6000_TARGET
3420 Shows that we are configured for an IBM RS/6000 system. This
3421 conditional should be eliminated (FIXME) and replaced by
3422 feature-specific macros. It was introduced in a haste and we are
3423 repenting at leisure.
3425 @item I386_USE_GENERIC_WATCHPOINTS
3426 An x86-based target can define this to use the generic x86 watchpoint
3427 support; see @ref{Algorithms, I386_USE_GENERIC_WATCHPOINTS}.
3429 @item SYMBOLS_CAN_START_WITH_DOLLAR
3430 @findex SYMBOLS_CAN_START_WITH_DOLLAR
3431 Some systems have routines whose names start with @samp{$}. Giving this
3432 macro a non-zero value tells @value{GDBN}'s expression parser to check for such
3433 routines when parsing tokens that begin with @samp{$}.
3435 On HP-UX, certain system routines (millicode) have names beginning with
3436 @samp{$} or @samp{$$}. For example, @code{$$dyncall} is a millicode
3437 routine that handles inter-space procedure calls on PA-RISC.
3439 @item DEPRECATED_INIT_EXTRA_FRAME_INFO (@var{fromleaf}, @var{frame})
3440 @findex DEPRECATED_INIT_EXTRA_FRAME_INFO
3441 If additional information about the frame is required this should be
3442 stored in @code{frame->extra_info}. Space for @code{frame->extra_info}
3443 is allocated using @code{frame_extra_info_zalloc}.
3445 @item DEPRECATED_INIT_FRAME_PC (@var{fromleaf}, @var{prev})
3446 @findex DEPRECATED_INIT_FRAME_PC
3447 This is a C statement that sets the pc of the frame pointed to by
3448 @var{prev}. [By default...]
3450 @item INNER_THAN (@var{lhs}, @var{rhs})
3452 Returns non-zero if stack address @var{lhs} is inner than (nearer to the
3453 stack top) stack address @var{rhs}. Define this as @code{lhs < rhs} if
3454 the target's stack grows downward in memory, or @code{lhs > rsh} if the
3457 @item gdbarch_in_function_epilogue_p (@var{gdbarch}, @var{pc})
3458 @findex gdbarch_in_function_epilogue_p
3459 Returns non-zero if the given @var{pc} is in the epilogue of a function.
3460 The epilogue of a function is defined as the part of a function where
3461 the stack frame of the function already has been destroyed up to the
3462 final `return from function call' instruction.
3464 @item SIGTRAMP_START (@var{pc})
3465 @findex SIGTRAMP_START
3466 @itemx SIGTRAMP_END (@var{pc})
3467 @findex SIGTRAMP_END
3468 Define these to be the start and end address of the @code{sigtramp} for the
3469 given @var{pc}. On machines where the address is just a compile time
3470 constant, the macro expansion will typically just ignore the supplied
3473 @item IN_SOLIB_CALL_TRAMPOLINE (@var{pc}, @var{name})
3474 @findex IN_SOLIB_CALL_TRAMPOLINE
3475 Define this to evaluate to nonzero if the program is stopped in the
3476 trampoline that connects to a shared library.
3478 @item IN_SOLIB_RETURN_TRAMPOLINE (@var{pc}, @var{name})
3479 @findex IN_SOLIB_RETURN_TRAMPOLINE
3480 Define this to evaluate to nonzero if the program is stopped in the
3481 trampoline that returns from a shared library.
3483 @item IN_SOLIB_DYNSYM_RESOLVE_CODE (@var{pc})
3484 @findex IN_SOLIB_DYNSYM_RESOLVE_CODE
3485 Define this to evaluate to nonzero if the program is stopped in the
3488 @item SKIP_SOLIB_RESOLVER (@var{pc})
3489 @findex SKIP_SOLIB_RESOLVER
3490 Define this to evaluate to the (nonzero) address at which execution
3491 should continue to get past the dynamic linker's symbol resolution
3492 function. A zero value indicates that it is not important or necessary
3493 to set a breakpoint to get through the dynamic linker and that single
3494 stepping will suffice.
3496 @item INTEGER_TO_ADDRESS (@var{type}, @var{buf})
3497 @findex INTEGER_TO_ADDRESS
3498 @cindex converting integers to addresses
3499 Define this when the architecture needs to handle non-pointer to address
3500 conversions specially. Converts that value to an address according to
3501 the current architectures conventions.
3503 @emph{Pragmatics: When the user copies a well defined expression from
3504 their source code and passes it, as a parameter, to @value{GDBN}'s
3505 @code{print} command, they should get the same value as would have been
3506 computed by the target program. Any deviation from this rule can cause
3507 major confusion and annoyance, and needs to be justified carefully. In
3508 other words, @value{GDBN} doesn't really have the freedom to do these
3509 conversions in clever and useful ways. It has, however, been pointed
3510 out that users aren't complaining about how @value{GDBN} casts integers
3511 to pointers; they are complaining that they can't take an address from a
3512 disassembly listing and give it to @code{x/i}. Adding an architecture
3513 method like @code{INTEGER_TO_ADDRESS} certainly makes it possible for
3514 @value{GDBN} to ``get it right'' in all circumstances.}
3516 @xref{Target Architecture Definition, , Pointers Are Not Always
3519 @item NO_HIF_SUPPORT
3520 @findex NO_HIF_SUPPORT
3521 (Specific to the a29k.)
3523 @item POINTER_TO_ADDRESS (@var{type}, @var{buf})
3524 @findex POINTER_TO_ADDRESS
3525 Assume that @var{buf} holds a pointer of type @var{type}, in the
3526 appropriate format for the current architecture. Return the byte
3527 address the pointer refers to.
3528 @xref{Target Architecture Definition, , Pointers Are Not Always Addresses}.
3530 @item REGISTER_CONVERTIBLE (@var{reg})
3531 @findex REGISTER_CONVERTIBLE
3532 Return non-zero if @var{reg} uses different raw and virtual formats.
3533 @xref{Target Architecture Definition, , Raw and Virtual Register Representations}.
3535 @item REGISTER_TO_VALUE(@var{regnum}, @var{type}, @var{from}, @var{to})
3536 @findex REGISTER_TO_VALUE
3537 Convert the raw contents of register @var{regnum} into a value of type
3539 @xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}.
3541 @item DEPRECATED_REGISTER_RAW_SIZE (@var{reg})
3542 @findex DEPRECATED_REGISTER_RAW_SIZE
3543 Return the raw size of @var{reg}; defaults to the size of the register's
3545 @xref{Target Architecture Definition, , Raw and Virtual Register Representations}.
3547 @item register_reggroup_p (@var{gdbarch}, @var{regnum}, @var{reggroup})
3548 @findex register_reggroup_p
3549 @cindex register groups
3550 Return non-zero if register @var{regnum} is a member of the register
3551 group @var{reggroup}.
3553 By default, registers are grouped as follows:
3556 @item float_reggroup
3557 Any register with a valid name and a floating-point type.
3558 @item vector_reggroup
3559 Any register with a valid name and a vector type.
3560 @item general_reggroup
3561 Any register with a valid name and a type other than vector or
3562 floating-point. @samp{float_reggroup}.
3564 @itemx restore_reggroup
3566 Any register with a valid name.
3569 @item DEPRECATED_REGISTER_VIRTUAL_SIZE (@var{reg})
3570 @findex DEPRECATED_REGISTER_VIRTUAL_SIZE
3571 Return the virtual size of @var{reg}; defaults to the size of the
3572 register's virtual type.
3573 Return the virtual size of @var{reg}.
3574 @xref{Target Architecture Definition, , Raw and Virtual Register Representations}.
3576 @item DEPRECATED_REGISTER_VIRTUAL_TYPE (@var{reg})
3577 @findex REGISTER_VIRTUAL_TYPE
3578 Return the virtual type of @var{reg}.
3579 @xref{Target Architecture Definition, , Raw and Virtual Register Representations}.
3581 @item struct type *register_type (@var{gdbarch}, @var{reg})
3582 @findex register_type
3583 If defined, return the type of register @var{reg}. This function
3584 superseeds @code{DEPRECATED_REGISTER_VIRTUAL_TYPE}. @xref{Target Architecture
3585 Definition, , Raw and Virtual Register Representations}.
3587 @item REGISTER_CONVERT_TO_VIRTUAL(@var{reg}, @var{type}, @var{from}, @var{to})
3588 @findex REGISTER_CONVERT_TO_VIRTUAL
3589 Convert the value of register @var{reg} from its raw form to its virtual
3591 @xref{Target Architecture Definition, , Raw and Virtual Register Representations}.
3593 @item REGISTER_CONVERT_TO_RAW(@var{type}, @var{reg}, @var{from}, @var{to})
3594 @findex REGISTER_CONVERT_TO_RAW
3595 Convert the value of register @var{reg} from its virtual form to its raw
3597 @xref{Target Architecture Definition, , Raw and Virtual Register Representations}.
3599 @item const struct regset *regset_from_core_section (struct gdbarch * @var{gdbarch}, const char * @var{sect_name}, size_t @var{sect_size})
3600 @findex regset_from_core_section
3601 Return the appropriate register set for a core file section with name
3602 @var{sect_name} and size @var{sect_size}.
3605 @item RETURN_VALUE_ON_STACK(@var{type})
3606 @findex RETURN_VALUE_ON_STACK
3607 @cindex returning structures by value
3608 @cindex structures, returning by value
3610 Return non-zero if values of type TYPE are returned on the stack, using
3611 the ``struct convention'' (i.e., the caller provides a pointer to a
3612 buffer in which the callee should store the return value). This
3613 controls how the @samp{finish} command finds a function's return value,
3614 and whether an inferior function call reserves space on the stack for
3617 The full logic @value{GDBN} uses here is kind of odd.
3621 If the type being returned by value is not a structure, union, or array,
3622 and @code{RETURN_VALUE_ON_STACK} returns zero, then @value{GDBN}
3623 concludes the value is not returned using the struct convention.
3626 Otherwise, @value{GDBN} calls @code{USE_STRUCT_CONVENTION} (see below).
3627 If that returns non-zero, @value{GDBN} assumes the struct convention is
3631 In other words, to indicate that a given type is returned by value using
3632 the struct convention, that type must be either a struct, union, array,
3633 or something @code{RETURN_VALUE_ON_STACK} likes, @emph{and} something
3634 that @code{USE_STRUCT_CONVENTION} likes.
3636 Note that, in C and C@t{++}, arrays are never returned by value. In those
3637 languages, these predicates will always see a pointer type, never an
3638 array type. All the references above to arrays being returned by value
3639 apply only to other languages.
3641 @item SOFTWARE_SINGLE_STEP_P()
3642 @findex SOFTWARE_SINGLE_STEP_P
3643 Define this as 1 if the target does not have a hardware single-step
3644 mechanism. The macro @code{SOFTWARE_SINGLE_STEP} must also be defined.
3646 @item SOFTWARE_SINGLE_STEP(@var{signal}, @var{insert_breapoints_p})
3647 @findex SOFTWARE_SINGLE_STEP
3648 A function that inserts or removes (depending on
3649 @var{insert_breapoints_p}) breakpoints at each possible destinations of
3650 the next instruction. See @file{sparc-tdep.c} and @file{rs6000-tdep.c}
3653 @item SOFUN_ADDRESS_MAYBE_MISSING
3654 @findex SOFUN_ADDRESS_MAYBE_MISSING
3655 Somebody clever observed that, the more actual addresses you have in the
3656 debug information, the more time the linker has to spend relocating
3657 them. So whenever there's some other way the debugger could find the
3658 address it needs, you should omit it from the debug info, to make
3661 @code{SOFUN_ADDRESS_MAYBE_MISSING} indicates that a particular set of
3662 hacks of this sort are in use, affecting @code{N_SO} and @code{N_FUN}
3663 entries in stabs-format debugging information. @code{N_SO} stabs mark
3664 the beginning and ending addresses of compilation units in the text
3665 segment. @code{N_FUN} stabs mark the starts and ends of functions.
3667 @code{SOFUN_ADDRESS_MAYBE_MISSING} means two things:
3671 @code{N_FUN} stabs have an address of zero. Instead, you should find the
3672 addresses where the function starts by taking the function name from
3673 the stab, and then looking that up in the minsyms (the
3674 linker/assembler symbol table). In other words, the stab has the
3675 name, and the linker/assembler symbol table is the only place that carries
3679 @code{N_SO} stabs have an address of zero, too. You just look at the
3680 @code{N_FUN} stabs that appear before and after the @code{N_SO} stab,
3681 and guess the starting and ending addresses of the compilation unit from
3685 @item PCC_SOL_BROKEN
3686 @findex PCC_SOL_BROKEN
3687 (Used only in the Convex target.)
3689 @item PC_IN_SIGTRAMP (@var{pc}, @var{name})
3690 @findex PC_IN_SIGTRAMP
3692 The @dfn{sigtramp} is a routine that the kernel calls (which then calls
3693 the signal handler). On most machines it is a library routine that is
3694 linked into the executable.
3696 This function, given a program counter value in @var{pc} and the
3697 (possibly NULL) name of the function in which that @var{pc} resides,
3698 returns nonzero if the @var{pc} and/or @var{name} show that we are in
3701 @item PC_LOAD_SEGMENT
3702 @findex PC_LOAD_SEGMENT
3703 If defined, print information about the load segment for the program
3704 counter. (Defined only for the RS/6000.)
3708 If the program counter is kept in a register, then define this macro to
3709 be the number (greater than or equal to zero) of that register.
3711 This should only need to be defined if @code{TARGET_READ_PC} and
3712 @code{TARGET_WRITE_PC} are not defined.
3714 @item DEPRECATED_NPC_REGNUM
3715 @findex DEPRECATED_NPC_REGNUM
3716 The number of the ``next program counter'' register, if defined.
3718 @code{DEPRECATED_NPC_REGNUM} has been replaced by @code{TARGET_WRITE_PC}
3719 (@pxref{TARGET_WRITE_PC}).
3722 @findex PARM_BOUNDARY
3723 If non-zero, round arguments to a boundary of this many bits before
3724 pushing them on the stack.
3726 @item stabs_argument_has_addr (@var{gdbarch}, @var{type})
3727 @findex stabs_argument_has_addr
3728 @findex DEPRECATED_REG_STRUCT_HAS_ADDR
3729 @anchor{stabs_argument_has_addr} Define this to return nonzero if a
3730 function argument of type @var{type} is passed by reference instead of
3733 This method replaces @code{DEPRECATED_REG_STRUCT_HAS_ADDR}
3734 (@pxref{DEPRECATED_REG_STRUCT_HAS_ADDR}).
3736 @item PROCESS_LINENUMBER_HOOK
3737 @findex PROCESS_LINENUMBER_HOOK
3738 A hook defined for XCOFF reading.
3740 @item PROLOGUE_FIRSTLINE_OVERLAP
3741 @findex PROLOGUE_FIRSTLINE_OVERLAP
3742 (Only used in unsupported Convex configuration.)
3746 If defined, this is the number of the processor status register. (This
3747 definition is only used in generic code when parsing "$ps".)
3749 @item DEPRECATED_POP_FRAME
3750 @findex DEPRECATED_POP_FRAME
3752 If defined, used by @code{frame_pop} to remove a stack frame. This
3753 method has been superseeded by generic code.
3755 @item push_dummy_call (@var{gdbarch}, @var{func_addr}, @var{regcache}, @var{pc_addr}, @var{nargs}, @var{args}, @var{sp}, @var{struct_return}, @var{struct_addr})
3756 @findex push_dummy_call
3757 @findex DEPRECATED_PUSH_ARGUMENTS.
3758 @anchor{push_dummy_call} Define this to push the dummy frame's call to
3759 the inferior function onto the stack. In addition to pushing
3760 @var{nargs}, the code should push @var{struct_addr} (when
3761 @var{struct_return}), and the return address (@var{bp_addr}).
3763 Returns the updated top-of-stack pointer.
3765 This method replaces @code{DEPRECATED_PUSH_ARGUMENTS}.
3767 @item CORE_ADDR push_dummy_code (@var{gdbarch}, @var{sp}, @var{funaddr}, @var{using_gcc}, @var{args}, @var{nargs}, @var{value_type}, @var{real_pc}, @var{bp_addr})
3768 @findex push_dummy_code
3769 @findex DEPRECATED_FIX_CALL_DUMMY
3770 @anchor{push_dummy_code} Given a stack based call dummy, push the
3771 instruction sequence (including space for a breakpoint) to which the
3772 called function should return.
3774 Set @var{bp_addr} to the address at which the breakpoint instruction
3775 should be inserted, @var{real_pc} to the resume address when starting
3776 the call sequence, and return the updated inner-most stack address.
3778 By default, the stack is grown sufficient to hold a frame-aligned
3779 (@pxref{frame_align}) breakpoint, @var{bp_addr} is set to the address
3780 reserved for that breakpoint, and @var{real_pc} set to @var{funaddr}.
3782 This method replaces @code{DEPRECATED_CALL_DUMMY_WORDS},
3783 @code{DEPRECATED_SIZEOF_CALL_DUMMY_WORDS}, @code{CALL_DUMMY},
3784 @code{CALL_DUMMY_LOCATION}, @code{DEPRECATED_REGISTER_SIZE},
3785 @code{GDB_TARGET_IS_HPPA},
3786 @code{DEPRECATED_CALL_DUMMY_BREAKPOINT_OFFSET}, and
3787 @code{DEPRECATED_FIX_CALL_DUMMY}.
3789 @item DEPRECATED_PUSH_DUMMY_FRAME
3790 @findex DEPRECATED_PUSH_DUMMY_FRAME
3791 Used in @samp{call_function_by_hand} to create an artificial stack frame.
3793 @item DEPRECATED_REGISTER_BYTES
3794 @findex DEPRECATED_REGISTER_BYTES
3795 The total amount of space needed to store @value{GDBN}'s copy of the
3796 machine's register state.
3798 This is no longer needed. @value{GDBN} instead computes the size of the
3799 register buffer at run-time.
3801 @item REGISTER_NAME(@var{i})
3802 @findex REGISTER_NAME
3803 Return the name of register @var{i} as a string. May return @code{NULL}
3804 or @code{NUL} to indicate that register @var{i} is not valid.
3806 @item DEPRECATED_REG_STRUCT_HAS_ADDR (@var{gcc_p}, @var{type})
3807 @findex DEPRECATED_REG_STRUCT_HAS_ADDR
3808 @anchor{DEPRECATED_REG_STRUCT_HAS_ADDR}Define this to return 1 if the
3809 given type will be passed by pointer rather than directly.
3811 This method has been replaced by @code{stabs_argument_has_addr}
3812 (@pxref{stabs_argument_has_addr}).
3814 @item SAVE_DUMMY_FRAME_TOS (@var{sp})
3815 @findex SAVE_DUMMY_FRAME_TOS
3816 @anchor{SAVE_DUMMY_FRAME_TOS} Used in @samp{call_function_by_hand} to
3817 notify the target dependent code of the top-of-stack value that will be
3818 passed to the the inferior code. This is the value of the @code{SP}
3819 after both the dummy frame and space for parameters/results have been
3820 allocated on the stack. @xref{unwind_dummy_id}.
3822 @item SDB_REG_TO_REGNUM
3823 @findex SDB_REG_TO_REGNUM
3824 Define this to convert sdb register numbers into @value{GDBN} regnums. If not
3825 defined, no conversion will be done.
3827 @item SKIP_PERMANENT_BREAKPOINT
3828 @findex SKIP_PERMANENT_BREAKPOINT
3829 Advance the inferior's PC past a permanent breakpoint. @value{GDBN} normally
3830 steps over a breakpoint by removing it, stepping one instruction, and
3831 re-inserting the breakpoint. However, permanent breakpoints are
3832 hardwired into the inferior, and can't be removed, so this strategy
3833 doesn't work. Calling @code{SKIP_PERMANENT_BREAKPOINT} adjusts the processor's
3834 state so that execution will resume just after the breakpoint. This
3835 macro does the right thing even when the breakpoint is in the delay slot
3836 of a branch or jump.
3838 @item SKIP_PROLOGUE (@var{pc})
3839 @findex SKIP_PROLOGUE
3840 A C expression that returns the address of the ``real'' code beyond the
3841 function entry prologue found at @var{pc}.
3843 @item SKIP_TRAMPOLINE_CODE (@var{pc})
3844 @findex SKIP_TRAMPOLINE_CODE
3845 If the target machine has trampoline code that sits between callers and
3846 the functions being called, then define this macro to return a new PC
3847 that is at the start of the real function.
3851 If the stack-pointer is kept in a register, then define this macro to be
3852 the number (greater than or equal to zero) of that register, or -1 if
3853 there is no such register.
3855 @item STAB_REG_TO_REGNUM
3856 @findex STAB_REG_TO_REGNUM
3857 Define this to convert stab register numbers (as gotten from `r'
3858 declarations) into @value{GDBN} regnums. If not defined, no conversion will be
3861 @item DEPRECATED_STACK_ALIGN (@var{addr})
3862 @anchor{DEPRECATED_STACK_ALIGN}
3863 @findex DEPRECATED_STACK_ALIGN
3864 Define this to increase @var{addr} so that it meets the alignment
3865 requirements for the processor's stack.
3867 Unlike @ref{frame_align}, this function always adjusts @var{addr}
3870 By default, no stack alignment is performed.
3872 @item STEP_SKIPS_DELAY (@var{addr})
3873 @findex STEP_SKIPS_DELAY
3874 Define this to return true if the address is of an instruction with a
3875 delay slot. If a breakpoint has been placed in the instruction's delay
3876 slot, @value{GDBN} will single-step over that instruction before resuming
3877 normally. Currently only defined for the Mips.
3879 @item STORE_RETURN_VALUE (@var{type}, @var{regcache}, @var{valbuf})
3880 @findex STORE_RETURN_VALUE
3881 A C expression that writes the function return value, found in
3882 @var{valbuf}, into the @var{regcache}. @var{type} is the type of the
3883 value that is to be returned.
3885 @item SUN_FIXED_LBRAC_BUG
3886 @findex SUN_FIXED_LBRAC_BUG
3887 (Used only for Sun-3 and Sun-4 targets.)
3889 @item SYMBOL_RELOADING_DEFAULT
3890 @findex SYMBOL_RELOADING_DEFAULT
3891 The default value of the ``symbol-reloading'' variable. (Never defined in
3894 @item TARGET_CHAR_BIT
3895 @findex TARGET_CHAR_BIT
3896 Number of bits in a char; defaults to 8.
3898 @item TARGET_CHAR_SIGNED
3899 @findex TARGET_CHAR_SIGNED
3900 Non-zero if @code{char} is normally signed on this architecture; zero if
3901 it should be unsigned.
3903 The ISO C standard requires the compiler to treat @code{char} as
3904 equivalent to either @code{signed char} or @code{unsigned char}; any
3905 character in the standard execution set is supposed to be positive.
3906 Most compilers treat @code{char} as signed, but @code{char} is unsigned
3907 on the IBM S/390, RS6000, and PowerPC targets.
3909 @item TARGET_COMPLEX_BIT
3910 @findex TARGET_COMPLEX_BIT
3911 Number of bits in a complex number; defaults to @code{2 * TARGET_FLOAT_BIT}.
3913 At present this macro is not used.
3915 @item TARGET_DOUBLE_BIT
3916 @findex TARGET_DOUBLE_BIT
3917 Number of bits in a double float; defaults to @code{8 * TARGET_CHAR_BIT}.
3919 @item TARGET_DOUBLE_COMPLEX_BIT
3920 @findex TARGET_DOUBLE_COMPLEX_BIT
3921 Number of bits in a double complex; defaults to @code{2 * TARGET_DOUBLE_BIT}.
3923 At present this macro is not used.
3925 @item TARGET_FLOAT_BIT
3926 @findex TARGET_FLOAT_BIT
3927 Number of bits in a float; defaults to @code{4 * TARGET_CHAR_BIT}.
3929 @item TARGET_INT_BIT
3930 @findex TARGET_INT_BIT
3931 Number of bits in an integer; defaults to @code{4 * TARGET_CHAR_BIT}.
3933 @item TARGET_LONG_BIT
3934 @findex TARGET_LONG_BIT
3935 Number of bits in a long integer; defaults to @code{4 * TARGET_CHAR_BIT}.
3937 @item TARGET_LONG_DOUBLE_BIT
3938 @findex TARGET_LONG_DOUBLE_BIT
3939 Number of bits in a long double float;
3940 defaults to @code{2 * TARGET_DOUBLE_BIT}.
3942 @item TARGET_LONG_LONG_BIT
3943 @findex TARGET_LONG_LONG_BIT
3944 Number of bits in a long long integer; defaults to @code{2 * TARGET_LONG_BIT}.
3946 @item TARGET_PTR_BIT
3947 @findex TARGET_PTR_BIT
3948 Number of bits in a pointer; defaults to @code{TARGET_INT_BIT}.
3950 @item TARGET_SHORT_BIT
3951 @findex TARGET_SHORT_BIT
3952 Number of bits in a short integer; defaults to @code{2 * TARGET_CHAR_BIT}.
3954 @item TARGET_READ_PC
3955 @findex TARGET_READ_PC
3956 @itemx TARGET_WRITE_PC (@var{val}, @var{pid})
3957 @findex TARGET_WRITE_PC
3958 @anchor{TARGET_WRITE_PC}
3959 @itemx TARGET_READ_SP
3960 @findex TARGET_READ_SP
3961 @itemx TARGET_READ_FP
3962 @findex TARGET_READ_FP
3967 @anchor{TARGET_READ_SP} These change the behavior of @code{read_pc},
3968 @code{write_pc}, @code{read_sp} and @code{deprecated_read_fp}. For most
3969 targets, these may be left undefined. @value{GDBN} will call the read
3970 and write register functions with the relevant @code{_REGNUM} argument.
3972 These macros are useful when a target keeps one of these registers in a
3973 hard to get at place; for example, part in a segment register and part
3974 in an ordinary register.
3976 @xref{unwind_sp}, which replaces @code{TARGET_READ_SP}.
3978 @item TARGET_VIRTUAL_FRAME_POINTER(@var{pc}, @var{regp}, @var{offsetp})
3979 @findex TARGET_VIRTUAL_FRAME_POINTER
3980 Returns a @code{(register, offset)} pair representing the virtual frame
3981 pointer in use at the code address @var{pc}. If virtual frame pointers
3982 are not used, a default definition simply returns
3983 @code{DEPRECATED_FP_REGNUM}, with an offset of zero.
3985 @item TARGET_HAS_HARDWARE_WATCHPOINTS
3986 If non-zero, the target has support for hardware-assisted
3987 watchpoints. @xref{Algorithms, watchpoints}, for more details and
3988 other related macros.
3990 @item TARGET_PRINT_INSN (@var{addr}, @var{info})
3991 @findex TARGET_PRINT_INSN
3992 This is the function used by @value{GDBN} to print an assembly
3993 instruction. It prints the instruction at address @var{addr} in
3994 debugged memory and returns the length of the instruction, in bytes. If
3995 a target doesn't define its own printing routine, it defaults to an
3996 accessor function for the global pointer
3997 @code{deprecated_tm_print_insn}. This usually points to a function in
3998 the @code{opcodes} library (@pxref{Support Libraries, ,Opcodes}).
3999 @var{info} is a structure (of type @code{disassemble_info}) defined in
4000 @file{include/dis-asm.h} used to pass information to the instruction
4003 @item struct frame_id unwind_dummy_id (struct frame_info *@var{frame})
4004 @findex unwind_dummy_id
4005 @anchor{unwind_dummy_id} Given @var{frame} return a @code{struct
4006 frame_id} that uniquely identifies an inferior function call's dummy
4007 frame. The value returned must match the dummy frame stack value
4008 previously saved using @code{SAVE_DUMMY_FRAME_TOS}.
4009 @xref{SAVE_DUMMY_FRAME_TOS}.
4011 @item USE_STRUCT_CONVENTION (@var{gcc_p}, @var{type})
4012 @findex USE_STRUCT_CONVENTION
4013 If defined, this must be an expression that is nonzero if a value of the
4014 given @var{type} being returned from a function must have space
4015 allocated for it on the stack. @var{gcc_p} is true if the function
4016 being considered is known to have been compiled by GCC; this is helpful
4017 for systems where GCC is known to use different calling convention than
4020 @item VALUE_TO_REGISTER(@var{type}, @var{regnum}, @var{from}, @var{to})
4021 @findex VALUE_TO_REGISTER
4022 Convert a value of type @var{type} into the raw contents of register
4024 @xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}.
4026 @item VARIABLES_INSIDE_BLOCK (@var{desc}, @var{gcc_p})
4027 @findex VARIABLES_INSIDE_BLOCK
4028 For dbx-style debugging information, if the compiler puts variable
4029 declarations inside LBRAC/RBRAC blocks, this should be defined to be
4030 nonzero. @var{desc} is the value of @code{n_desc} from the
4031 @code{N_RBRAC} symbol, and @var{gcc_p} is true if @value{GDBN} has noticed the
4032 presence of either the @code{GCC_COMPILED_SYMBOL} or the
4033 @code{GCC2_COMPILED_SYMBOL}. By default, this is 0.
4035 @item OS9K_VARIABLES_INSIDE_BLOCK (@var{desc}, @var{gcc_p})
4036 @findex OS9K_VARIABLES_INSIDE_BLOCK
4037 Similarly, for OS/9000. Defaults to 1.
4040 Motorola M68K target conditionals.
4044 Define this to be the 4-bit location of the breakpoint trap vector. If
4045 not defined, it will default to @code{0xf}.
4047 @item REMOTE_BPT_VECTOR
4048 Defaults to @code{1}.
4050 @item NAME_OF_MALLOC
4051 @findex NAME_OF_MALLOC
4052 A string containing the name of the function to call in order to
4053 allocate some memory in the inferior. The default value is "malloc".
4057 @section Adding a New Target
4059 @cindex adding a target
4060 The following files add a target to @value{GDBN}:
4064 @item gdb/config/@var{arch}/@var{ttt}.mt
4065 Contains a Makefile fragment specific to this target. Specifies what
4066 object files are needed for target @var{ttt}, by defining
4067 @samp{TDEPFILES=@dots{}} and @samp{TDEPLIBS=@dots{}}. Also specifies
4068 the header file which describes @var{ttt}, by defining @samp{TM_FILE=
4071 You can also define @samp{TM_CFLAGS}, @samp{TM_CLIBS}, @samp{TM_CDEPS},
4072 but these are now deprecated, replaced by autoconf, and may go away in
4073 future versions of @value{GDBN}.
4075 @item gdb/@var{ttt}-tdep.c
4076 Contains any miscellaneous code required for this target machine. On
4077 some machines it doesn't exist at all. Sometimes the macros in
4078 @file{tm-@var{ttt}.h} become very complicated, so they are implemented
4079 as functions here instead, and the macro is simply defined to call the
4080 function. This is vastly preferable, since it is easier to understand
4083 @item gdb/@var{arch}-tdep.c
4084 @itemx gdb/@var{arch}-tdep.h
4085 This often exists to describe the basic layout of the target machine's
4086 processor chip (registers, stack, etc.). If used, it is included by
4087 @file{@var{ttt}-tdep.h}. It can be shared among many targets that use
4090 @item gdb/config/@var{arch}/tm-@var{ttt}.h
4091 (@file{tm.h} is a link to this file, created by @code{configure}). Contains
4092 macro definitions about the target machine's registers, stack frame
4093 format and instructions.
4095 New targets do not need this file and should not create it.
4097 @item gdb/config/@var{arch}/tm-@var{arch}.h
4098 This often exists to describe the basic layout of the target machine's
4099 processor chip (registers, stack, etc.). If used, it is included by
4100 @file{tm-@var{ttt}.h}. It can be shared among many targets that use the
4103 New targets do not need this file and should not create it.
4107 If you are adding a new operating system for an existing CPU chip, add a
4108 @file{config/tm-@var{os}.h} file that describes the operating system
4109 facilities that are unusual (extra symbol table info; the breakpoint
4110 instruction needed; etc.). Then write a @file{@var{arch}/tm-@var{os}.h}
4111 that just @code{#include}s @file{tm-@var{arch}.h} and
4112 @file{config/tm-@var{os}.h}.
4115 @section Converting an existing Target Architecture to Multi-arch
4116 @cindex converting targets to multi-arch
4118 This section describes the current accepted best practice for converting
4119 an existing target architecture to the multi-arch framework.
4121 The process consists of generating, testing, posting and committing a
4122 sequence of patches. Each patch must contain a single change, for
4128 Directly convert a group of functions into macros (the conversion does
4129 not change the behavior of any of the functions).
4132 Replace a non-multi-arch with a multi-arch mechanism (e.g.,
4136 Enable multi-arch level one.
4139 Delete one or more files.
4144 There isn't a size limit on a patch, however, a developer is strongly
4145 encouraged to keep the patch size down.
4147 Since each patch is well defined, and since each change has been tested
4148 and shows no regressions, the patches are considered @emph{fairly}
4149 obvious. Such patches, when submitted by developers listed in the
4150 @file{MAINTAINERS} file, do not need approval. Occasional steps in the
4151 process may be more complicated and less clear. The developer is
4152 expected to use their judgment and is encouraged to seek advice as
4155 @subsection Preparation
4157 The first step is to establish control. Build (with @option{-Werror}
4158 enabled) and test the target so that there is a baseline against which
4159 the debugger can be compared.
4161 At no stage can the test results regress or @value{GDBN} stop compiling
4162 with @option{-Werror}.
4164 @subsection Add the multi-arch initialization code
4166 The objective of this step is to establish the basic multi-arch
4167 framework. It involves
4172 The addition of a @code{@var{arch}_gdbarch_init} function@footnote{The
4173 above is from the original example and uses K&R C. @value{GDBN}
4174 has since converted to ISO C but lets ignore that.} that creates
4177 static struct gdbarch *
4178 d10v_gdbarch_init (info, arches)
4179 struct gdbarch_info info;
4180 struct gdbarch_list *arches;
4182 struct gdbarch *gdbarch;
4183 /* there is only one d10v architecture */
4185 return arches->gdbarch;
4186 gdbarch = gdbarch_alloc (&info, NULL);
4194 A per-architecture dump function to print any architecture specific
4198 mips_dump_tdep (struct gdbarch *current_gdbarch,
4199 struct ui_file *file)
4201 @dots{} code to print architecture specific info @dots{}
4206 A change to @code{_initialize_@var{arch}_tdep} to register this new
4210 _initialize_mips_tdep (void)
4212 gdbarch_register (bfd_arch_mips, mips_gdbarch_init,
4217 Add the macro @code{GDB_MULTI_ARCH}, defined as 0 (zero), to the file@*
4218 @file{config/@var{arch}/tm-@var{arch}.h}.
4222 @subsection Update multi-arch incompatible mechanisms
4224 Some mechanisms do not work with multi-arch. They include:
4227 @item FRAME_FIND_SAVED_REGS
4228 Replaced with @code{DEPRECATED_FRAME_INIT_SAVED_REGS}
4232 At this stage you could also consider converting the macros into
4235 @subsection Prepare for multi-arch level to one
4237 Temporally set @code{GDB_MULTI_ARCH} to @code{GDB_MULTI_ARCH_PARTIAL}
4238 and then build and start @value{GDBN} (the change should not be
4239 committed). @value{GDBN} may not build, and once built, it may die with
4240 an internal error listing the architecture methods that must be
4243 Fix any build problems (patch(es)).
4245 Convert all the architecture methods listed, which are only macros, into
4246 functions (patch(es)).
4248 Update @code{@var{arch}_gdbarch_init} to set all the missing
4249 architecture methods and wrap the corresponding macros in @code{#if
4250 !GDB_MULTI_ARCH} (patch(es)).
4252 @subsection Set multi-arch level one
4254 Change the value of @code{GDB_MULTI_ARCH} to GDB_MULTI_ARCH_PARTIAL (a
4257 Any problems with throwing ``the switch'' should have been fixed
4260 @subsection Convert remaining macros
4262 Suggest converting macros into functions (and setting the corresponding
4263 architecture method) in small batches.
4265 @subsection Set multi-arch level to two
4267 This should go smoothly.
4269 @subsection Delete the TM file
4271 The @file{tm-@var{arch}.h} can be deleted. @file{@var{arch}.mt} and
4272 @file{configure.in} updated.
4275 @node Target Vector Definition
4277 @chapter Target Vector Definition
4278 @cindex target vector
4280 The target vector defines the interface between @value{GDBN}'s
4281 abstract handling of target systems, and the nitty-gritty code that
4282 actually exercises control over a process or a serial port.
4283 @value{GDBN} includes some 30-40 different target vectors; however,
4284 each configuration of @value{GDBN} includes only a few of them.
4286 @section File Targets
4288 Both executables and core files have target vectors.
4290 @section Standard Protocol and Remote Stubs
4292 @value{GDBN}'s file @file{remote.c} talks a serial protocol to code
4293 that runs in the target system. @value{GDBN} provides several sample
4294 @dfn{stubs} that can be integrated into target programs or operating
4295 systems for this purpose; they are named @file{*-stub.c}.
4297 The @value{GDBN} user's manual describes how to put such a stub into
4298 your target code. What follows is a discussion of integrating the
4299 SPARC stub into a complicated operating system (rather than a simple
4300 program), by Stu Grossman, the author of this stub.
4302 The trap handling code in the stub assumes the following upon entry to
4307 %l1 and %l2 contain pc and npc respectively at the time of the trap;
4313 you are in the correct trap window.
4316 As long as your trap handler can guarantee those conditions, then there
4317 is no reason why you shouldn't be able to ``share'' traps with the stub.
4318 The stub has no requirement that it be jumped to directly from the
4319 hardware trap vector. That is why it calls @code{exceptionHandler()},
4320 which is provided by the external environment. For instance, this could
4321 set up the hardware traps to actually execute code which calls the stub
4322 first, and then transfers to its own trap handler.
4324 For the most point, there probably won't be much of an issue with
4325 ``sharing'' traps, as the traps we use are usually not used by the kernel,
4326 and often indicate unrecoverable error conditions. Anyway, this is all
4327 controlled by a table, and is trivial to modify. The most important
4328 trap for us is for @code{ta 1}. Without that, we can't single step or
4329 do breakpoints. Everything else is unnecessary for the proper operation
4330 of the debugger/stub.
4332 From reading the stub, it's probably not obvious how breakpoints work.
4333 They are simply done by deposit/examine operations from @value{GDBN}.
4335 @section ROM Monitor Interface
4337 @section Custom Protocols
4339 @section Transport Layer
4341 @section Builtin Simulator
4344 @node Native Debugging
4346 @chapter Native Debugging
4347 @cindex native debugging
4349 Several files control @value{GDBN}'s configuration for native support:
4353 @item gdb/config/@var{arch}/@var{xyz}.mh
4354 Specifies Makefile fragments needed by a @emph{native} configuration on
4355 machine @var{xyz}. In particular, this lists the required
4356 native-dependent object files, by defining @samp{NATDEPFILES=@dots{}}.
4357 Also specifies the header file which describes native support on
4358 @var{xyz}, by defining @samp{NAT_FILE= nm-@var{xyz}.h}. You can also
4359 define @samp{NAT_CFLAGS}, @samp{NAT_ADD_FILES}, @samp{NAT_CLIBS},
4360 @samp{NAT_CDEPS}, etc.; see @file{Makefile.in}.
4362 @emph{Maintainer's note: The @file{.mh} suffix is because this file
4363 originally contained @file{Makefile} fragments for hosting @value{GDBN}
4364 on machine @var{xyz}. While the file is no longer used for this
4365 purpose, the @file{.mh} suffix remains. Perhaps someone will
4366 eventually rename these fragments so that they have a @file{.mn}
4369 @item gdb/config/@var{arch}/nm-@var{xyz}.h
4370 (@file{nm.h} is a link to this file, created by @code{configure}). Contains C
4371 macro definitions describing the native system environment, such as
4372 child process control and core file support.
4374 @item gdb/@var{xyz}-nat.c
4375 Contains any miscellaneous C code required for this native support of
4376 this machine. On some machines it doesn't exist at all.
4379 There are some ``generic'' versions of routines that can be used by
4380 various systems. These can be customized in various ways by macros
4381 defined in your @file{nm-@var{xyz}.h} file. If these routines work for
4382 the @var{xyz} host, you can just include the generic file's name (with
4383 @samp{.o}, not @samp{.c}) in @code{NATDEPFILES}.
4385 Otherwise, if your machine needs custom support routines, you will need
4386 to write routines that perform the same functions as the generic file.
4387 Put them into @file{@var{xyz}-nat.c}, and put @file{@var{xyz}-nat.o}
4388 into @code{NATDEPFILES}.
4392 This contains the @emph{target_ops vector} that supports Unix child
4393 processes on systems which use ptrace and wait to control the child.
4396 This contains the @emph{target_ops vector} that supports Unix child
4397 processes on systems which use /proc to control the child.
4400 This does the low-level grunge that uses Unix system calls to do a ``fork
4401 and exec'' to start up a child process.
4404 This is the low level interface to inferior processes for systems using
4405 the Unix @code{ptrace} call in a vanilla way.
4408 @section Native core file Support
4409 @cindex native core files
4412 @findex fetch_core_registers
4413 @item core-aout.c::fetch_core_registers()
4414 Support for reading registers out of a core file. This routine calls
4415 @code{register_addr()}, see below. Now that BFD is used to read core
4416 files, virtually all machines should use @code{core-aout.c}, and should
4417 just provide @code{fetch_core_registers} in @code{@var{xyz}-nat.c} (or
4418 @code{REGISTER_U_ADDR} in @code{nm-@var{xyz}.h}).
4420 @item core-aout.c::register_addr()
4421 If your @code{nm-@var{xyz}.h} file defines the macro
4422 @code{REGISTER_U_ADDR(addr, blockend, regno)}, it should be defined to
4423 set @code{addr} to the offset within the @samp{user} struct of @value{GDBN}
4424 register number @code{regno}. @code{blockend} is the offset within the
4425 ``upage'' of @code{u.u_ar0}. If @code{REGISTER_U_ADDR} is defined,
4426 @file{core-aout.c} will define the @code{register_addr()} function and
4427 use the macro in it. If you do not define @code{REGISTER_U_ADDR}, but
4428 you are using the standard @code{fetch_core_registers()}, you will need
4429 to define your own version of @code{register_addr()}, put it into your
4430 @code{@var{xyz}-nat.c} file, and be sure @code{@var{xyz}-nat.o} is in
4431 the @code{NATDEPFILES} list. If you have your own
4432 @code{fetch_core_registers()}, you may not need a separate
4433 @code{register_addr()}. Many custom @code{fetch_core_registers()}
4434 implementations simply locate the registers themselves.@refill
4437 When making @value{GDBN} run native on a new operating system, to make it
4438 possible to debug core files, you will need to either write specific
4439 code for parsing your OS's core files, or customize
4440 @file{bfd/trad-core.c}. First, use whatever @code{#include} files your
4441 machine uses to define the struct of registers that is accessible
4442 (possibly in the u-area) in a core file (rather than
4443 @file{machine/reg.h}), and an include file that defines whatever header
4444 exists on a core file (e.g. the u-area or a @code{struct core}). Then
4445 modify @code{trad_unix_core_file_p} to use these values to set up the
4446 section information for the data segment, stack segment, any other
4447 segments in the core file (perhaps shared library contents or control
4448 information), ``registers'' segment, and if there are two discontiguous
4449 sets of registers (e.g. integer and float), the ``reg2'' segment. This
4450 section information basically delimits areas in the core file in a
4451 standard way, which the section-reading routines in BFD know how to seek
4454 Then back in @value{GDBN}, you need a matching routine called
4455 @code{fetch_core_registers}. If you can use the generic one, it's in
4456 @file{core-aout.c}; if not, it's in your @file{@var{xyz}-nat.c} file.
4457 It will be passed a char pointer to the entire ``registers'' segment,
4458 its length, and a zero; or a char pointer to the entire ``regs2''
4459 segment, its length, and a 2. The routine should suck out the supplied
4460 register values and install them into @value{GDBN}'s ``registers'' array.
4462 If your system uses @file{/proc} to control processes, and uses ELF
4463 format core files, then you may be able to use the same routines for
4464 reading the registers out of processes and out of core files.
4472 @section shared libraries
4474 @section Native Conditionals
4475 @cindex native conditionals
4477 When @value{GDBN} is configured and compiled, various macros are
4478 defined or left undefined, to control compilation when the host and
4479 target systems are the same. These macros should be defined (or left
4480 undefined) in @file{nm-@var{system}.h}.
4484 @findex ATTACH_DETACH
4485 If defined, then @value{GDBN} will include support for the @code{attach} and
4486 @code{detach} commands.
4488 @item CHILD_PREPARE_TO_STORE
4489 @findex CHILD_PREPARE_TO_STORE
4490 If the machine stores all registers at once in the child process, then
4491 define this to ensure that all values are correct. This usually entails
4492 a read from the child.
4494 [Note that this is incorrectly defined in @file{xm-@var{system}.h} files
4497 @item FETCH_INFERIOR_REGISTERS
4498 @findex FETCH_INFERIOR_REGISTERS
4499 Define this if the native-dependent code will provide its own routines
4500 @code{fetch_inferior_registers} and @code{store_inferior_registers} in
4501 @file{@var{host}-nat.c}. If this symbol is @emph{not} defined, and
4502 @file{infptrace.c} is included in this configuration, the default
4503 routines in @file{infptrace.c} are used for these functions.
4505 @item FILES_INFO_HOOK
4506 @findex FILES_INFO_HOOK
4507 (Only defined for Convex.)
4511 This macro is normally defined to be the number of the first floating
4512 point register, if the machine has such registers. As such, it would
4513 appear only in target-specific code. However, @file{/proc} support uses this
4514 to decide whether floats are in use on this target.
4516 @item GET_LONGJMP_TARGET
4517 @findex GET_LONGJMP_TARGET
4518 For most machines, this is a target-dependent parameter. On the
4519 DECstation and the Iris, this is a native-dependent parameter, since
4520 @file{setjmp.h} is needed to define it.
4522 This macro determines the target PC address that @code{longjmp} will jump to,
4523 assuming that we have just stopped at a longjmp breakpoint. It takes a
4524 @code{CORE_ADDR *} as argument, and stores the target PC value through this
4525 pointer. It examines the current state of the machine as needed.
4527 @item I386_USE_GENERIC_WATCHPOINTS
4528 An x86-based machine can define this to use the generic x86 watchpoint
4529 support; see @ref{Algorithms, I386_USE_GENERIC_WATCHPOINTS}.
4532 @findex KERNEL_U_ADDR
4533 Define this to the address of the @code{u} structure (the ``user
4534 struct'', also known as the ``u-page'') in kernel virtual memory. @value{GDBN}
4535 needs to know this so that it can subtract this address from absolute
4536 addresses in the upage, that are obtained via ptrace or from core files.
4537 On systems that don't need this value, set it to zero.
4539 @item KERNEL_U_ADDR_BSD
4540 @findex KERNEL_U_ADDR_BSD
4541 Define this to cause @value{GDBN} to determine the address of @code{u} at
4542 runtime, by using Berkeley-style @code{nlist} on the kernel's image in
4545 @item KERNEL_U_ADDR_HPUX
4546 @findex KERNEL_U_ADDR_HPUX
4547 Define this to cause @value{GDBN} to determine the address of @code{u} at
4548 runtime, by using HP-style @code{nlist} on the kernel's image in the
4551 @item ONE_PROCESS_WRITETEXT
4552 @findex ONE_PROCESS_WRITETEXT
4553 Define this to be able to, when a breakpoint insertion fails, warn the
4554 user that another process may be running with the same executable.
4557 @findex PROC_NAME_FMT
4558 Defines the format for the name of a @file{/proc} device. Should be
4559 defined in @file{nm.h} @emph{only} in order to override the default
4560 definition in @file{procfs.c}.
4563 @findex PTRACE_FP_BUG
4564 See @file{mach386-xdep.c}.
4566 @item PTRACE_ARG3_TYPE
4567 @findex PTRACE_ARG3_TYPE
4568 The type of the third argument to the @code{ptrace} system call, if it
4569 exists and is different from @code{int}.
4571 @item REGISTER_U_ADDR
4572 @findex REGISTER_U_ADDR
4573 Defines the offset of the registers in the ``u area''.
4575 @item SHELL_COMMAND_CONCAT
4576 @findex SHELL_COMMAND_CONCAT
4577 If defined, is a string to prefix on the shell command used to start the
4582 If defined, this is the name of the shell to use to run the inferior.
4583 Defaults to @code{"/bin/sh"}.
4585 @item SOLIB_ADD (@var{filename}, @var{from_tty}, @var{targ}, @var{readsyms})
4587 Define this to expand into an expression that will cause the symbols in
4588 @var{filename} to be added to @value{GDBN}'s symbol table. If
4589 @var{readsyms} is zero symbols are not read but any necessary low level
4590 processing for @var{filename} is still done.
4592 @item SOLIB_CREATE_INFERIOR_HOOK
4593 @findex SOLIB_CREATE_INFERIOR_HOOK
4594 Define this to expand into any shared-library-relocation code that you
4595 want to be run just after the child process has been forked.
4597 @item START_INFERIOR_TRAPS_EXPECTED
4598 @findex START_INFERIOR_TRAPS_EXPECTED
4599 When starting an inferior, @value{GDBN} normally expects to trap
4601 the shell execs, and once when the program itself execs. If the actual
4602 number of traps is something other than 2, then define this macro to
4603 expand into the number expected.
4605 @item SVR4_SHARED_LIBS
4606 @findex SVR4_SHARED_LIBS
4607 Define this to indicate that SVR4-style shared libraries are in use.
4611 This determines whether small routines in @file{*-tdep.c}, which
4612 translate register values between @value{GDBN}'s internal
4613 representation and the @file{/proc} representation, are compiled.
4616 @findex U_REGS_OFFSET
4617 This is the offset of the registers in the upage. It need only be
4618 defined if the generic ptrace register access routines in
4619 @file{infptrace.c} are being used (that is, @file{infptrace.c} is
4620 configured in, and @code{FETCH_INFERIOR_REGISTERS} is not defined). If
4621 the default value from @file{infptrace.c} is good enough, leave it
4624 The default value means that u.u_ar0 @emph{points to} the location of
4625 the registers. I'm guessing that @code{#define U_REGS_OFFSET 0} means
4626 that @code{u.u_ar0} @emph{is} the location of the registers.
4630 See @file{objfiles.c}.
4633 @findex DEBUG_PTRACE
4634 Define this to debug @code{ptrace} calls.
4638 @node Support Libraries
4640 @chapter Support Libraries
4645 BFD provides support for @value{GDBN} in several ways:
4648 @item identifying executable and core files
4649 BFD will identify a variety of file types, including a.out, coff, and
4650 several variants thereof, as well as several kinds of core files.
4652 @item access to sections of files
4653 BFD parses the file headers to determine the names, virtual addresses,
4654 sizes, and file locations of all the various named sections in files
4655 (such as the text section or the data section). @value{GDBN} simply
4656 calls BFD to read or write section @var{x} at byte offset @var{y} for
4659 @item specialized core file support
4660 BFD provides routines to determine the failing command name stored in a
4661 core file, the signal with which the program failed, and whether a core
4662 file matches (i.e.@: could be a core dump of) a particular executable
4665 @item locating the symbol information
4666 @value{GDBN} uses an internal interface of BFD to determine where to find the
4667 symbol information in an executable file or symbol-file. @value{GDBN} itself
4668 handles the reading of symbols, since BFD does not ``understand'' debug
4669 symbols, but @value{GDBN} uses BFD's cached information to find the symbols,
4674 @cindex opcodes library
4676 The opcodes library provides @value{GDBN}'s disassembler. (It's a separate
4677 library because it's also used in binutils, for @file{objdump}).
4686 @cindex regular expressions library
4697 @item SIGN_EXTEND_CHAR
4699 @item SWITCH_ENUM_BUG
4714 This chapter covers topics that are lower-level than the major
4715 algorithms of @value{GDBN}.
4720 Cleanups are a structured way to deal with things that need to be done
4723 When your code does something (e.g., @code{xmalloc} some memory, or
4724 @code{open} a file) that needs to be undone later (e.g., @code{xfree}
4725 the memory or @code{close} the file), it can make a cleanup. The
4726 cleanup will be done at some future point: when the command is finished
4727 and control returns to the top level; when an error occurs and the stack
4728 is unwound; or when your code decides it's time to explicitly perform
4729 cleanups. Alternatively you can elect to discard the cleanups you
4735 @item struct cleanup *@var{old_chain};
4736 Declare a variable which will hold a cleanup chain handle.
4738 @findex make_cleanup
4739 @item @var{old_chain} = make_cleanup (@var{function}, @var{arg});
4740 Make a cleanup which will cause @var{function} to be called with
4741 @var{arg} (a @code{char *}) later. The result, @var{old_chain}, is a
4742 handle that can later be passed to @code{do_cleanups} or
4743 @code{discard_cleanups}. Unless you are going to call
4744 @code{do_cleanups} or @code{discard_cleanups}, you can ignore the result
4745 from @code{make_cleanup}.
4748 @item do_cleanups (@var{old_chain});
4749 Do all cleanups added to the chain since the corresponding
4750 @code{make_cleanup} call was made.
4752 @findex discard_cleanups
4753 @item discard_cleanups (@var{old_chain});
4754 Same as @code{do_cleanups} except that it just removes the cleanups from
4755 the chain and does not call the specified functions.
4758 Cleanups are implemented as a chain. The handle returned by
4759 @code{make_cleanups} includes the cleanup passed to the call and any
4760 later cleanups appended to the chain (but not yet discarded or
4764 make_cleanup (a, 0);
4766 struct cleanup *old = make_cleanup (b, 0);
4774 will call @code{c()} and @code{b()} but will not call @code{a()}. The
4775 cleanup that calls @code{a()} will remain in the cleanup chain, and will
4776 be done later unless otherwise discarded.@refill
4778 Your function should explicitly do or discard the cleanups it creates.
4779 Failing to do this leads to non-deterministic behavior since the caller
4780 will arbitrarily do or discard your functions cleanups. This need leads
4781 to two common cleanup styles.
4783 The first style is try/finally. Before it exits, your code-block calls
4784 @code{do_cleanups} with the old cleanup chain and thus ensures that your
4785 code-block's cleanups are always performed. For instance, the following
4786 code-segment avoids a memory leak problem (even when @code{error} is
4787 called and a forced stack unwind occurs) by ensuring that the
4788 @code{xfree} will always be called:
4791 struct cleanup *old = make_cleanup (null_cleanup, 0);
4792 data = xmalloc (sizeof blah);
4793 make_cleanup (xfree, data);
4798 The second style is try/except. Before it exits, your code-block calls
4799 @code{discard_cleanups} with the old cleanup chain and thus ensures that
4800 any created cleanups are not performed. For instance, the following
4801 code segment, ensures that the file will be closed but only if there is
4805 FILE *file = fopen ("afile", "r");
4806 struct cleanup *old = make_cleanup (close_file, file);
4808 discard_cleanups (old);
4812 Some functions, e.g. @code{fputs_filtered()} or @code{error()}, specify
4813 that they ``should not be called when cleanups are not in place''. This
4814 means that any actions you need to reverse in the case of an error or
4815 interruption must be on the cleanup chain before you call these
4816 functions, since they might never return to your code (they
4817 @samp{longjmp} instead).
4819 @section Per-architecture module data
4820 @cindex per-architecture module data
4821 @cindex multi-arch data
4822 @cindex data-pointer, per-architecture/per-module
4824 The multi-arch framework includes a mechanism for adding module specific
4825 per-architecture data-pointers to the @code{struct gdbarch} architecture
4828 A module registers one or more per-architecture data-pointers using the
4829 function @code{register_gdbarch_data}:
4831 @deftypefun struct gdbarch_data *register_gdbarch_data (gdbarch_data_init_ftype *@var{init}, gdbarch_data_free_ftype *@var{free})
4833 The @var{init} function is used to obtain an initial value for a
4834 per-architecture data-pointer. The function is called, after the
4835 architecture has been created, when the data-pointer is still
4836 uninitialized (@code{NULL}) and its value has been requested via a call
4837 to @code{gdbarch_data}. A data-pointer can also be initialize
4838 explicitly using @code{set_gdbarch_data}.
4840 The @var{free} function is called when a data-pointer needs to be
4841 destroyed. This occurs when either the corresponding @code{struct
4842 gdbarch} object is being destroyed or when @code{set_gdbarch_data} is
4843 overriding a non-@code{NULL} data-pointer value.
4845 The function @code{register_gdbarch_data} returns a @code{struct
4846 gdbarch_data} that is used to identify the data-pointer that was added
4851 A typical module has @code{init} and @code{free} functions of the form:
4854 static struct gdbarch_data *nozel_handle;
4856 nozel_init (struct gdbarch *gdbarch)
4858 struct nozel *data = XMALLOC (struct nozel);
4864 nozel_free (struct gdbarch *gdbarch, void *data)
4870 Since uninitialized (@code{NULL}) data-pointers are initialized
4871 on-demand, an @code{init} function is free to call other modules that
4872 use data-pointers. Those modules data-pointers will be initialized as
4873 needed. Care should be taken to ensure that the @code{init} call graph
4874 does not contain cycles.
4876 The data-pointer is registered with the call:
4880 _initialize_nozel (void)
4882 nozel_handle = register_gdbarch_data (nozel_init, nozel_free);
4886 The per-architecture data-pointer is accessed using the function:
4888 @deftypefun void *gdbarch_data (struct gdbarch *@var{gdbarch}, struct gdbarch_data *@var{data_handle})
4889 Given the architecture @var{arch} and module data handle
4890 @var{data_handle} (returned by @code{register_gdbarch_data}, this
4891 function returns the current value of the per-architecture data-pointer.
4894 The non-@code{NULL} data-pointer returned by @code{gdbarch_data} should
4895 be saved in a local variable and then used directly:
4899 nozel_total (struct gdbarch *gdbarch)
4902 struct nozel *data = gdbarch_data (gdbarch, nozel_handle);
4908 It is also possible to directly initialize the data-pointer using:
4910 @deftypefun void set_gdbarch_data (struct gdbarch *@var{gdbarch}, struct gdbarch_data *handle, void *@var{pointer})
4911 Update the data-pointer corresponding to @var{handle} with the value of
4912 @var{pointer}. If the previous data-pointer value is non-NULL, then it
4913 is freed using data-pointers @var{free} function.
4916 This function is used by modules that require a mechanism for explicitly
4917 setting the per-architecture data-pointer during architecture creation:
4920 /* Called during architecture creation. */
4922 set_gdbarch_nozel (struct gdbarch *gdbarch,
4925 struct nozel *data = XMALLOC (struct nozel);
4927 set_gdbarch_data (gdbarch, nozel_handle, nozel);
4932 /* Default, called when nozel not set by set_gdbarch_nozel(). */
4934 nozel_init (struct gdbarch *gdbarch)
4936 struct nozel *default_nozel = XMALLOC (struc nozel);
4938 return default_nozel;
4944 _initialize_nozel (void)
4946 nozel_handle = register_gdbarch_data (nozel_init, NULL);
4951 Note that an @code{init} function still needs to be registered. It is
4952 used to initialize the data-pointer when the architecture creation phase
4953 fail to set an initial value.
4956 @section Wrapping Output Lines
4957 @cindex line wrap in output
4960 Output that goes through @code{printf_filtered} or @code{fputs_filtered}
4961 or @code{fputs_demangled} needs only to have calls to @code{wrap_here}
4962 added in places that would be good breaking points. The utility
4963 routines will take care of actually wrapping if the line width is
4966 The argument to @code{wrap_here} is an indentation string which is
4967 printed @emph{only} if the line breaks there. This argument is saved
4968 away and used later. It must remain valid until the next call to
4969 @code{wrap_here} or until a newline has been printed through the
4970 @code{*_filtered} functions. Don't pass in a local variable and then
4973 It is usually best to call @code{wrap_here} after printing a comma or
4974 space. If you call it before printing a space, make sure that your
4975 indentation properly accounts for the leading space that will print if
4976 the line wraps there.
4978 Any function or set of functions that produce filtered output must
4979 finish by printing a newline, to flush the wrap buffer, before switching
4980 to unfiltered (@code{printf}) output. Symbol reading routines that
4981 print warnings are a good example.
4983 @section @value{GDBN} Coding Standards
4984 @cindex coding standards
4986 @value{GDBN} follows the GNU coding standards, as described in
4987 @file{etc/standards.texi}. This file is also available for anonymous
4988 FTP from GNU archive sites. @value{GDBN} takes a strict interpretation
4989 of the standard; in general, when the GNU standard recommends a practice
4990 but does not require it, @value{GDBN} requires it.
4992 @value{GDBN} follows an additional set of coding standards specific to
4993 @value{GDBN}, as described in the following sections.
4998 @value{GDBN} assumes an ISO/IEC 9899:1990 (a.k.a.@: ISO C90) compliant
5001 @value{GDBN} does not assume an ISO C or POSIX compliant C library.
5004 @subsection Memory Management
5006 @value{GDBN} does not use the functions @code{malloc}, @code{realloc},
5007 @code{calloc}, @code{free} and @code{asprintf}.
5009 @value{GDBN} uses the functions @code{xmalloc}, @code{xrealloc} and
5010 @code{xcalloc} when allocating memory. Unlike @code{malloc} et.al.@:
5011 these functions do not return when the memory pool is empty. Instead,
5012 they unwind the stack using cleanups. These functions return
5013 @code{NULL} when requested to allocate a chunk of memory of size zero.
5015 @emph{Pragmatics: By using these functions, the need to check every
5016 memory allocation is removed. These functions provide portable
5019 @value{GDBN} does not use the function @code{free}.
5021 @value{GDBN} uses the function @code{xfree} to return memory to the
5022 memory pool. Consistent with ISO-C, this function ignores a request to
5023 free a @code{NULL} pointer.
5025 @emph{Pragmatics: On some systems @code{free} fails when passed a
5026 @code{NULL} pointer.}
5028 @value{GDBN} can use the non-portable function @code{alloca} for the
5029 allocation of small temporary values (such as strings).
5031 @emph{Pragmatics: This function is very non-portable. Some systems
5032 restrict the memory being allocated to no more than a few kilobytes.}
5034 @value{GDBN} uses the string function @code{xstrdup} and the print
5035 function @code{xasprintf}.
5037 @emph{Pragmatics: @code{asprintf} and @code{strdup} can fail. Print
5038 functions such as @code{sprintf} are very prone to buffer overflow
5042 @subsection Compiler Warnings
5043 @cindex compiler warnings
5045 With few exceptions, developers should include the configuration option
5046 @samp{--enable-gdb-build-warnings=,-Werror} when building @value{GDBN}.
5047 The exceptions are listed in the file @file{gdb/MAINTAINERS}.
5049 This option causes @value{GDBN} (when built using GCC) to be compiled
5050 with a carefully selected list of compiler warning flags. Any warnings
5051 from those flags being treated as errors.
5053 The current list of warning flags includes:
5057 Since @value{GDBN} coding standard requires all functions to be declared
5058 using a prototype, the flag has the side effect of ensuring that
5059 prototyped functions are always visible with out resorting to
5060 @samp{-Wstrict-prototypes}.
5063 Such code often appears to work except on instruction set architectures
5064 that use register windows.
5071 @itemx -Wformat-nonliteral
5072 Since @value{GDBN} uses the @code{format printf} attribute on all
5073 @code{printf} like functions these check not just @code{printf} calls
5074 but also calls to functions such as @code{fprintf_unfiltered}.
5077 This warning includes uses of the assignment operator within an
5078 @code{if} statement.
5080 @item -Wpointer-arith
5082 @item -Wuninitialized
5085 @emph{Pragmatics: Due to the way that @value{GDBN} is implemented most
5086 functions have unused parameters. Consequently the warning
5087 @samp{-Wunused-parameter} is precluded from the list. The macro
5088 @code{ATTRIBUTE_UNUSED} is not used as it leads to false negatives ---
5089 it is not an error to have @code{ATTRIBUTE_UNUSED} on a parameter that
5090 is being used. The options @samp{-Wall} and @samp{-Wunused} are also
5091 precluded because they both include @samp{-Wunused-parameter}.}
5093 @emph{Pragmatics: @value{GDBN} has not simply accepted the warnings
5094 enabled by @samp{-Wall -Werror -W...}. Instead it is selecting warnings
5095 when and where their benefits can be demonstrated.}
5097 @subsection Formatting
5099 @cindex source code formatting
5100 The standard GNU recommendations for formatting must be followed
5103 A function declaration should not have its name in column zero. A
5104 function definition should have its name in column zero.
5108 static void foo (void);
5116 @emph{Pragmatics: This simplifies scripting. Function definitions can
5117 be found using @samp{^function-name}.}
5119 There must be a space between a function or macro name and the opening
5120 parenthesis of its argument list (except for macro definitions, as
5121 required by C). There must not be a space after an open paren/bracket
5122 or before a close paren/bracket.
5124 While additional whitespace is generally helpful for reading, do not use
5125 more than one blank line to separate blocks, and avoid adding whitespace
5126 after the end of a program line (as of 1/99, some 600 lines had
5127 whitespace after the semicolon). Excess whitespace causes difficulties
5128 for @code{diff} and @code{patch} utilities.
5130 Pointers are declared using the traditional K&R C style:
5144 @subsection Comments
5146 @cindex comment formatting
5147 The standard GNU requirements on comments must be followed strictly.
5149 Block comments must appear in the following form, with no @code{/*}- or
5150 @code{*/}-only lines, and no leading @code{*}:
5153 /* Wait for control to return from inferior to debugger. If inferior
5154 gets a signal, we may decide to start it up again instead of
5155 returning. That is why there is a loop in this function. When
5156 this function actually returns it means the inferior should be left
5157 stopped and @value{GDBN} should read more commands. */
5160 (Note that this format is encouraged by Emacs; tabbing for a multi-line
5161 comment works correctly, and @kbd{M-q} fills the block consistently.)
5163 Put a blank line between the block comments preceding function or
5164 variable definitions, and the definition itself.
5166 In general, put function-body comments on lines by themselves, rather
5167 than trying to fit them into the 20 characters left at the end of a
5168 line, since either the comment or the code will inevitably get longer
5169 than will fit, and then somebody will have to move it anyhow.
5173 @cindex C data types
5174 Code must not depend on the sizes of C data types, the format of the
5175 host's floating point numbers, the alignment of anything, or the order
5176 of evaluation of expressions.
5178 @cindex function usage
5179 Use functions freely. There are only a handful of compute-bound areas
5180 in @value{GDBN} that might be affected by the overhead of a function
5181 call, mainly in symbol reading. Most of @value{GDBN}'s performance is
5182 limited by the target interface (whether serial line or system call).
5184 However, use functions with moderation. A thousand one-line functions
5185 are just as hard to understand as a single thousand-line function.
5187 @emph{Macros are bad, M'kay.}
5188 (But if you have to use a macro, make sure that the macro arguments are
5189 protected with parentheses.)
5193 Declarations like @samp{struct foo *} should be used in preference to
5194 declarations like @samp{typedef struct foo @{ @dots{} @} *foo_ptr}.
5197 @subsection Function Prototypes
5198 @cindex function prototypes
5200 Prototypes must be used when both @emph{declaring} and @emph{defining}
5201 a function. Prototypes for @value{GDBN} functions must include both the
5202 argument type and name, with the name matching that used in the actual
5203 function definition.
5205 All external functions should have a declaration in a header file that
5206 callers include, except for @code{_initialize_*} functions, which must
5207 be external so that @file{init.c} construction works, but shouldn't be
5208 visible to random source files.
5210 Where a source file needs a forward declaration of a static function,
5211 that declaration must appear in a block near the top of the source file.
5214 @subsection Internal Error Recovery
5216 During its execution, @value{GDBN} can encounter two types of errors.
5217 User errors and internal errors. User errors include not only a user
5218 entering an incorrect command but also problems arising from corrupt
5219 object files and system errors when interacting with the target.
5220 Internal errors include situations where @value{GDBN} has detected, at
5221 run time, a corrupt or erroneous situation.
5223 When reporting an internal error, @value{GDBN} uses
5224 @code{internal_error} and @code{gdb_assert}.
5226 @value{GDBN} must not call @code{abort} or @code{assert}.
5228 @emph{Pragmatics: There is no @code{internal_warning} function. Either
5229 the code detected a user error, recovered from it and issued a
5230 @code{warning} or the code failed to correctly recover from the user
5231 error and issued an @code{internal_error}.}
5233 @subsection File Names
5235 Any file used when building the core of @value{GDBN} must be in lower
5236 case. Any file used when building the core of @value{GDBN} must be 8.3
5237 unique. These requirements apply to both source and generated files.
5239 @emph{Pragmatics: The core of @value{GDBN} must be buildable on many
5240 platforms including DJGPP and MacOS/HFS. Every time an unfriendly file
5241 is introduced to the build process both @file{Makefile.in} and
5242 @file{configure.in} need to be modified accordingly. Compare the
5243 convoluted conversion process needed to transform @file{COPYING} into
5244 @file{copying.c} with the conversion needed to transform
5245 @file{version.in} into @file{version.c}.}
5247 Any file non 8.3 compliant file (that is not used when building the core
5248 of @value{GDBN}) must be added to @file{gdb/config/djgpp/fnchange.lst}.
5250 @emph{Pragmatics: This is clearly a compromise.}
5252 When @value{GDBN} has a local version of a system header file (ex
5253 @file{string.h}) the file name based on the POSIX header prefixed with
5254 @file{gdb_} (@file{gdb_string.h}). These headers should be relatively
5255 independent: they should use only macros defined by @file{configure},
5256 the compiler, or the host; they should include only system headers; they
5257 should refer only to system types. They may be shared between multiple
5258 programs, e.g.@: @value{GDBN} and @sc{gdbserver}.
5260 For other files @samp{-} is used as the separator.
5263 @subsection Include Files
5265 A @file{.c} file should include @file{defs.h} first.
5267 A @file{.c} file should directly include the @code{.h} file of every
5268 declaration and/or definition it directly refers to. It cannot rely on
5271 A @file{.h} file should directly include the @code{.h} file of every
5272 declaration and/or definition it directly refers to. It cannot rely on
5273 indirect inclusion. Exception: The file @file{defs.h} does not need to
5274 be directly included.
5276 An external declaration should only appear in one include file.
5278 An external declaration should never appear in a @code{.c} file.
5279 Exception: a declaration for the @code{_initialize} function that
5280 pacifies @option{-Wmissing-declaration}.
5282 A @code{typedef} definition should only appear in one include file.
5284 An opaque @code{struct} declaration can appear in multiple @file{.h}
5285 files. Where possible, a @file{.h} file should use an opaque
5286 @code{struct} declaration instead of an include.
5288 All @file{.h} files should be wrapped in:
5291 #ifndef INCLUDE_FILE_NAME_H
5292 #define INCLUDE_FILE_NAME_H
5298 @subsection Clean Design and Portable Implementation
5301 In addition to getting the syntax right, there's the little question of
5302 semantics. Some things are done in certain ways in @value{GDBN} because long
5303 experience has shown that the more obvious ways caused various kinds of
5306 @cindex assumptions about targets
5307 You can't assume the byte order of anything that comes from a target
5308 (including @var{value}s, object files, and instructions). Such things
5309 must be byte-swapped using @code{SWAP_TARGET_AND_HOST} in
5310 @value{GDBN}, or one of the swap routines defined in @file{bfd.h},
5311 such as @code{bfd_get_32}.
5313 You can't assume that you know what interface is being used to talk to
5314 the target system. All references to the target must go through the
5315 current @code{target_ops} vector.
5317 You can't assume that the host and target machines are the same machine
5318 (except in the ``native'' support modules). In particular, you can't
5319 assume that the target machine's header files will be available on the
5320 host machine. Target code must bring along its own header files --
5321 written from scratch or explicitly donated by their owner, to avoid
5325 Insertion of new @code{#ifdef}'s will be frowned upon. It's much better
5326 to write the code portably than to conditionalize it for various
5329 @cindex system dependencies
5330 New @code{#ifdef}'s which test for specific compilers or manufacturers
5331 or operating systems are unacceptable. All @code{#ifdef}'s should test
5332 for features. The information about which configurations contain which
5333 features should be segregated into the configuration files. Experience
5334 has proven far too often that a feature unique to one particular system
5335 often creeps into other systems; and that a conditional based on some
5336 predefined macro for your current system will become worthless over
5337 time, as new versions of your system come out that behave differently
5338 with regard to this feature.
5340 Adding code that handles specific architectures, operating systems,
5341 target interfaces, or hosts, is not acceptable in generic code.
5343 @cindex portable file name handling
5344 @cindex file names, portability
5345 One particularly notorious area where system dependencies tend to
5346 creep in is handling of file names. The mainline @value{GDBN} code
5347 assumes Posix semantics of file names: absolute file names begin with
5348 a forward slash @file{/}, slashes are used to separate leading
5349 directories, case-sensitive file names. These assumptions are not
5350 necessarily true on non-Posix systems such as MS-Windows. To avoid
5351 system-dependent code where you need to take apart or construct a file
5352 name, use the following portable macros:
5355 @findex HAVE_DOS_BASED_FILE_SYSTEM
5356 @item HAVE_DOS_BASED_FILE_SYSTEM
5357 This preprocessing symbol is defined to a non-zero value on hosts
5358 whose filesystems belong to the MS-DOS/MS-Windows family. Use this
5359 symbol to write conditional code which should only be compiled for
5362 @findex IS_DIR_SEPARATOR
5363 @item IS_DIR_SEPARATOR (@var{c})
5364 Evaluates to a non-zero value if @var{c} is a directory separator
5365 character. On Unix and GNU/Linux systems, only a slash @file{/} is
5366 such a character, but on Windows, both @file{/} and @file{\} will
5369 @findex IS_ABSOLUTE_PATH
5370 @item IS_ABSOLUTE_PATH (@var{file})
5371 Evaluates to a non-zero value if @var{file} is an absolute file name.
5372 For Unix and GNU/Linux hosts, a name which begins with a slash
5373 @file{/} is absolute. On DOS and Windows, @file{d:/foo} and
5374 @file{x:\bar} are also absolute file names.
5376 @findex FILENAME_CMP
5377 @item FILENAME_CMP (@var{f1}, @var{f2})
5378 Calls a function which compares file names @var{f1} and @var{f2} as
5379 appropriate for the underlying host filesystem. For Posix systems,
5380 this simply calls @code{strcmp}; on case-insensitive filesystems it
5381 will call @code{strcasecmp} instead.
5383 @findex DIRNAME_SEPARATOR
5384 @item DIRNAME_SEPARATOR
5385 Evaluates to a character which separates directories in
5386 @code{PATH}-style lists, typically held in environment variables.
5387 This character is @samp{:} on Unix, @samp{;} on DOS and Windows.
5389 @findex SLASH_STRING
5391 This evaluates to a constant string you should use to produce an
5392 absolute filename from leading directories and the file's basename.
5393 @code{SLASH_STRING} is @code{"/"} on most systems, but might be
5394 @code{"\\"} for some Windows-based ports.
5397 In addition to using these macros, be sure to use portable library
5398 functions whenever possible. For example, to extract a directory or a
5399 basename part from a file name, use the @code{dirname} and
5400 @code{basename} library functions (available in @code{libiberty} for
5401 platforms which don't provide them), instead of searching for a slash
5402 with @code{strrchr}.
5404 Another way to generalize @value{GDBN} along a particular interface is with an
5405 attribute struct. For example, @value{GDBN} has been generalized to handle
5406 multiple kinds of remote interfaces---not by @code{#ifdef}s everywhere, but
5407 by defining the @code{target_ops} structure and having a current target (as
5408 well as a stack of targets below it, for memory references). Whenever
5409 something needs to be done that depends on which remote interface we are
5410 using, a flag in the current target_ops structure is tested (e.g.,
5411 @code{target_has_stack}), or a function is called through a pointer in the
5412 current target_ops structure. In this way, when a new remote interface
5413 is added, only one module needs to be touched---the one that actually
5414 implements the new remote interface. Other examples of
5415 attribute-structs are BFD access to multiple kinds of object file
5416 formats, or @value{GDBN}'s access to multiple source languages.
5418 Please avoid duplicating code. For example, in @value{GDBN} 3.x all
5419 the code interfacing between @code{ptrace} and the rest of
5420 @value{GDBN} was duplicated in @file{*-dep.c}, and so changing
5421 something was very painful. In @value{GDBN} 4.x, these have all been
5422 consolidated into @file{infptrace.c}. @file{infptrace.c} can deal
5423 with variations between systems the same way any system-independent
5424 file would (hooks, @code{#if defined}, etc.), and machines which are
5425 radically different don't need to use @file{infptrace.c} at all.
5427 All debugging code must be controllable using the @samp{set debug
5428 @var{module}} command. Do not use @code{printf} to print trace
5429 messages. Use @code{fprintf_unfiltered(gdb_stdlog, ...}. Do not use
5430 @code{#ifdef DEBUG}.
5435 @chapter Porting @value{GDBN}
5436 @cindex porting to new machines
5438 Most of the work in making @value{GDBN} compile on a new machine is in
5439 specifying the configuration of the machine. This is done in a
5440 dizzying variety of header files and configuration scripts, which we
5441 hope to make more sensible soon. Let's say your new host is called an
5442 @var{xyz} (e.g., @samp{sun4}), and its full three-part configuration
5443 name is @code{@var{arch}-@var{xvend}-@var{xos}} (e.g.,
5444 @samp{sparc-sun-sunos4}). In particular:
5448 In the top level directory, edit @file{config.sub} and add @var{arch},
5449 @var{xvend}, and @var{xos} to the lists of supported architectures,
5450 vendors, and operating systems near the bottom of the file. Also, add
5451 @var{xyz} as an alias that maps to
5452 @code{@var{arch}-@var{xvend}-@var{xos}}. You can test your changes by
5456 ./config.sub @var{xyz}
5463 ./config.sub @code{@var{arch}-@var{xvend}-@var{xos}}
5467 which should both respond with @code{@var{arch}-@var{xvend}-@var{xos}}
5468 and no error messages.
5471 You need to port BFD, if that hasn't been done already. Porting BFD is
5472 beyond the scope of this manual.
5475 To configure @value{GDBN} itself, edit @file{gdb/configure.host} to recognize
5476 your system and set @code{gdb_host} to @var{xyz}, and (unless your
5477 desired target is already available) also edit @file{gdb/configure.tgt},
5478 setting @code{gdb_target} to something appropriate (for instance,
5481 @emph{Maintainer's note: Work in progress. The file
5482 @file{gdb/configure.host} originally needed to be modified when either a
5483 new native target or a new host machine was being added to @value{GDBN}.
5484 Recent changes have removed this requirement. The file now only needs
5485 to be modified when adding a new native configuration. This will likely
5486 changed again in the future.}
5489 Finally, you'll need to specify and define @value{GDBN}'s host-, native-, and
5490 target-dependent @file{.h} and @file{.c} files used for your
5496 @chapter Releasing @value{GDBN}
5497 @cindex making a new release of gdb
5499 @section Versions and Branches
5501 @subsection Version Identifiers
5503 @value{GDBN}'s version is determined by the file @file{gdb/version.in}.
5505 @value{GDBN}'s mainline uses ISO dates to differentiate between
5506 versions. The CVS repository uses @var{YYYY}-@var{MM}-@var{DD}-cvs
5507 while the corresponding snapshot uses @var{YYYYMMDD}.
5509 @value{GDBN}'s release branch uses a slightly more complicated scheme.
5510 When the branch is first cut, the mainline version identifier is
5511 prefixed with the @var{major}.@var{minor} from of the previous release
5512 series but with .90 appended. As draft releases are drawn from the
5513 branch, the minor minor number (.90) is incremented. Once the first
5514 release (@var{M}.@var{N}) has been made, the version prefix is updated
5515 to @var{M}.@var{N}.0.90 (dot zero, dot ninety). Follow on releases have
5516 an incremented minor minor version number (.0).
5518 Using 5.1 (previous) and 5.2 (current), the example below illustrates a
5519 typical sequence of version identifiers:
5523 final release from previous branch
5524 @item 2002-03-03-cvs
5525 main-line the day the branch is cut
5526 @item 5.1.90-2002-03-03-cvs
5527 corresponding branch version
5529 first draft release candidate
5530 @item 5.1.91-2002-03-17-cvs
5531 updated branch version
5533 second draft release candidate
5534 @item 5.1.92-2002-03-31-cvs
5535 updated branch version
5537 final release candidate (see below)
5540 @item 5.2.0.90-2002-04-07-cvs
5541 updated CVS branch version
5543 second official release
5550 Minor minor minor draft release candidates such as 5.2.0.91 have been
5551 omitted from the example. Such release candidates are, typically, never
5554 For 5.1.93 the bziped tar ball @file{gdb-5.1.93.tar.bz2} is just the
5555 official @file{gdb-5.2.tar} renamed and compressed.
5558 To avoid version conflicts, vendors are expected to modify the file
5559 @file{gdb/version.in} to include a vendor unique alphabetic identifier
5560 (an official @value{GDBN} release never uses alphabetic characters in
5561 its version identifer).
5563 Since @value{GDBN} does not make minor minor minor releases (e.g.,
5564 5.1.0.1) the conflict between that and a minor minor draft release
5565 identifier (e.g., 5.1.0.90) is avoided.
5568 @subsection Branches
5570 @value{GDBN} draws a release series (5.2, 5.2.1, @dots{}) from a single
5571 release branch (gdb_5_2-branch). Since minor minor minor releases
5572 (5.1.0.1) are not made, the need to branch the release branch is avoided
5573 (it also turns out that the effort required for such a a branch and
5574 release is significantly greater than the effort needed to create a new
5575 release from the head of the release branch).
5577 Releases 5.0 and 5.1 used branch and release tags of the form:
5580 gdb_N_M-YYYY-MM-DD-branchpoint
5581 gdb_N_M-YYYY-MM-DD-branch
5582 gdb_M_N-YYYY-MM-DD-release
5585 Release 5.2 is trialing the branch and release tags:
5588 gdb_N_M-YYYY-MM-DD-branchpoint
5590 gdb_M_N-YYYY-MM-DD-release
5593 @emph{Pragmatics: The branchpoint and release tags need to identify when
5594 a branch and release are made. The branch tag, denoting the head of the
5595 branch, does not have this criteria.}
5598 @section Branch Commit Policy
5600 The branch commit policy is pretty slack. @value{GDBN} releases 5.0,
5601 5.1 and 5.2 all used the below:
5605 The @file{gdb/MAINTAINERS} file still holds.
5607 Don't fix something on the branch unless/until it is also fixed in the
5608 trunk. If this isn't possible, mentioning it in the @file{gdb/PROBLEMS}
5609 file is better than committing a hack.
5611 When considering a patch for the branch, suggested criteria include:
5612 Does it fix a build? Does it fix the sequence @kbd{break main; run}
5613 when debugging a static binary?
5615 The further a change is from the core of @value{GDBN}, the less likely
5616 the change will worry anyone (e.g., target specific code).
5618 Only post a proposal to change the core of @value{GDBN} after you've
5619 sent individual bribes to all the people listed in the
5620 @file{MAINTAINERS} file @t{;-)}
5623 @emph{Pragmatics: Provided updates are restricted to non-core
5624 functionality there is little chance that a broken change will be fatal.
5625 This means that changes such as adding a new architectures or (within
5626 reason) support for a new host are considered acceptable.}
5629 @section Obsoleting code
5631 Before anything else, poke the other developers (and around the source
5632 code) to see if there is anything that can be removed from @value{GDBN}
5633 (an old target, an unused file).
5635 Obsolete code is identified by adding an @code{OBSOLETE} prefix to every
5636 line. Doing this means that it is easy to identify something that has
5637 been obsoleted when greping through the sources.
5639 The process is done in stages --- this is mainly to ensure that the
5640 wider @value{GDBN} community has a reasonable opportunity to respond.
5641 Remember, everything on the Internet takes a week.
5645 Post the proposal on @email{gdb@@sources.redhat.com, the GDB mailing
5646 list} Creating a bug report to track the task's state, is also highly
5651 Post the proposal on @email{gdb-announce@@sources.redhat.com, the GDB
5652 Announcement mailing list}.
5656 Go through and edit all relevant files and lines so that they are
5657 prefixed with the word @code{OBSOLETE}.
5659 Wait until the next GDB version, containing this obsolete code, has been
5662 Remove the obsolete code.
5666 @emph{Maintainer note: While removing old code is regrettable it is
5667 hopefully better for @value{GDBN}'s long term development. Firstly it
5668 helps the developers by removing code that is either no longer relevant
5669 or simply wrong. Secondly since it removes any history associated with
5670 the file (effectively clearing the slate) the developer has a much freer
5671 hand when it comes to fixing broken files.}
5675 @section Before the Branch
5677 The most important objective at this stage is to find and fix simple
5678 changes that become a pain to track once the branch is created. For
5679 instance, configuration problems that stop @value{GDBN} from even
5680 building. If you can't get the problem fixed, document it in the
5681 @file{gdb/PROBLEMS} file.
5683 @subheading Prompt for @file{gdb/NEWS}
5685 People always forget. Send a post reminding them but also if you know
5686 something interesting happened add it yourself. The @code{schedule}
5687 script will mention this in its e-mail.
5689 @subheading Review @file{gdb/README}
5691 Grab one of the nightly snapshots and then walk through the
5692 @file{gdb/README} looking for anything that can be improved. The
5693 @code{schedule} script will mention this in its e-mail.
5695 @subheading Refresh any imported files.
5697 A number of files are taken from external repositories. They include:
5701 @file{texinfo/texinfo.tex}
5703 @file{config.guess} et.@: al.@: (see the top-level @file{MAINTAINERS}
5706 @file{etc/standards.texi}, @file{etc/make-stds.texi}
5709 @subheading Check the ARI
5711 @uref{http://sources.redhat.com/gdb/ari,,A.R.I.} is an @code{awk} script
5712 (Awk Regression Index ;-) that checks for a number of errors and coding
5713 conventions. The checks include things like using @code{malloc} instead
5714 of @code{xmalloc} and file naming problems. There shouldn't be any
5717 @subsection Review the bug data base
5719 Close anything obviously fixed.
5721 @subsection Check all cross targets build
5723 The targets are listed in @file{gdb/MAINTAINERS}.
5726 @section Cut the Branch
5728 @subheading Create the branch
5733 $ V=`echo $v | sed 's/\./_/g'`
5734 $ D=`date -u +%Y-%m-%d`
5737 $ echo cvs -f -d :ext:sources.redhat.com:/cvs/src rtag \
5738 -D $D-gmt gdb_$V-$D-branchpoint insight+dejagnu
5739 cvs -f -d :ext:sources.redhat.com:/cvs/src rtag
5740 -D 2002-03-03-gmt gdb_5_2-2002-03-03-branchpoint insight+dejagnu
5743 $ echo cvs -f -d :ext:sources.redhat.com:/cvs/src rtag \
5744 -b -r gdb_$V-$D-branchpoint gdb_$V-branch insight+dejagnu
5745 cvs -f -d :ext:sources.redhat.com:/cvs/src rtag \
5746 -b -r gdb_5_2-2002-03-03-branchpoint gdb_5_2-branch insight+dejagnu
5754 by using @kbd{-D YYYY-MM-DD-gmt} the branch is forced to an exact
5757 the trunk is first taged so that the branch point can easily be found
5759 Insight (which includes GDB) and dejagnu are all tagged at the same time
5761 @file{version.in} gets bumped to avoid version number conflicts
5763 the reading of @file{.cvsrc} is disabled using @file{-f}
5766 @subheading Update @file{version.in}
5771 $ V=`echo $v | sed 's/\./_/g'`
5775 $ echo cvs -f -d :ext:sources.redhat.com:/cvs/src co \
5776 -r gdb_$V-branch src/gdb/version.in
5777 cvs -f -d :ext:sources.redhat.com:/cvs/src co
5778 -r gdb_5_2-branch src/gdb/version.in
5780 U src/gdb/version.in
5782 $ echo $u.90-0000-00-00-cvs > version.in
5784 5.1.90-0000-00-00-cvs
5785 $ cvs -f commit version.in
5790 @file{0000-00-00} is used as a date to pump prime the version.in update
5793 @file{.90} and the previous branch version are used as fairly arbitrary
5794 initial branch version number
5798 @subheading Update the web and news pages
5802 @subheading Tweak cron to track the new branch
5804 The file @file{gdbadmin/cron/crontab} contains gdbadmin's cron table.
5805 This file needs to be updated so that:
5809 a daily timestamp is added to the file @file{version.in}
5811 the new branch is included in the snapshot process
5815 See the file @file{gdbadmin/cron/README} for how to install the updated
5818 The file @file{gdbadmin/ss/README} should also be reviewed to reflect
5819 any changes. That file is copied to both the branch/ and current/
5820 snapshot directories.
5823 @subheading Update the NEWS and README files
5825 The @file{NEWS} file needs to be updated so that on the branch it refers
5826 to @emph{changes in the current release} while on the trunk it also
5827 refers to @emph{changes since the current release}.
5829 The @file{README} file needs to be updated so that it refers to the
5832 @subheading Post the branch info
5834 Send an announcement to the mailing lists:
5838 @email{gdb-announce@@sources.redhat.com, GDB Announcement mailing list}
5840 @email{gdb@@sources.redhat.com, GDB Discsussion mailing list} and
5841 @email{gdb-testers@@sources.redhat.com, GDB Discsussion mailing list}
5844 @emph{Pragmatics: The branch creation is sent to the announce list to
5845 ensure that people people not subscribed to the higher volume discussion
5848 The announcement should include:
5854 how to check out the branch using CVS
5856 the date/number of weeks until the release
5858 the branch commit policy
5862 @section Stabilize the branch
5864 Something goes here.
5866 @section Create a Release
5868 The process of creating and then making available a release is broken
5869 down into a number of stages. The first part addresses the technical
5870 process of creating a releasable tar ball. The later stages address the
5871 process of releasing that tar ball.
5873 When making a release candidate just the first section is needed.
5875 @subsection Create a release candidate
5877 The objective at this stage is to create a set of tar balls that can be
5878 made available as a formal release (or as a less formal release
5881 @subsubheading Freeze the branch
5883 Send out an e-mail notifying everyone that the branch is frozen to
5884 @email{gdb-patches@@sources.redhat.com}.
5886 @subsubheading Establish a few defaults.
5891 $ t=/sourceware/snapshot-tmp/gdbadmin-tmp
5893 /sourceware/snapshot-tmp/gdbadmin-tmp/gdb_5_2-branch/5.2
5897 /sourceware/snapshot-tmp/gdbadmin-tmp/gdb_5_2-branch/5.2
5899 /home/gdbadmin/bin/autoconf
5908 Check the @code{autoconf} version carefully. You want to be using the
5909 version taken from the @file{binutils} snapshot directory, which can be
5910 found at @uref{ftp://sources.redhat.com/pub/binutils/}. It is very
5911 unlikely that a system installed version of @code{autoconf} (e.g.,
5912 @file{/usr/bin/autoconf}) is correct.
5915 @subsubheading Check out the relevant modules:
5918 $ for m in gdb insight dejagnu
5920 ( mkdir -p $m && cd $m && cvs -q -f -d /cvs/src co -P -r $b $m )
5930 The reading of @file{.cvsrc} is disabled (@file{-f}) so that there isn't
5931 any confusion between what is written here and what your local
5932 @code{cvs} really does.
5935 @subsubheading Update relevant files.
5941 Major releases get their comments added as part of the mainline. Minor
5942 releases should probably mention any significant bugs that were fixed.
5944 Don't forget to include the @file{ChangeLog} entry.
5947 $ emacs gdb/src/gdb/NEWS
5952 $ cp gdb/src/gdb/NEWS insight/src/gdb/NEWS
5953 $ cp gdb/src/gdb/ChangeLog insight/src/gdb/ChangeLog
5958 You'll need to update:
5970 $ emacs gdb/src/gdb/README
5975 $ cp gdb/src/gdb/README insight/src/gdb/README
5976 $ cp gdb/src/gdb/ChangeLog insight/src/gdb/ChangeLog
5979 @emph{Maintainer note: Hopefully the @file{README} file was reviewed
5980 before the initial branch was cut so just a simple substitute is needed
5983 @emph{Maintainer note: Other projects generate @file{README} and
5984 @file{INSTALL} from the core documentation. This might be worth
5987 @item gdb/version.in
5990 $ echo $v > gdb/src/gdb/version.in
5991 $ cat gdb/src/gdb/version.in
5993 $ emacs gdb/src/gdb/version.in
5996 ... Bump to version ...
5998 $ cp gdb/src/gdb/version.in insight/src/gdb/version.in
5999 $ cp gdb/src/gdb/ChangeLog insight/src/gdb/ChangeLog
6002 @item dejagnu/src/dejagnu/configure.in
6004 Dejagnu is more complicated. The version number is a parameter to
6005 @code{AM_INIT_AUTOMAKE}. Tweak it to read something like gdb-5.1.91.
6007 Don't forget to re-generate @file{configure}.
6009 Don't forget to include a @file{ChangeLog} entry.
6012 $ emacs dejagnu/src/dejagnu/configure.in
6017 $ ( cd dejagnu/src/dejagnu && autoconf )
6022 @subsubheading Do the dirty work
6024 This is identical to the process used to create the daily snapshot.
6027 $ for m in gdb insight
6029 ( cd $m/src && gmake -f src-release $m.tar )
6031 $ ( m=dejagnu; cd $m/src && gmake -f src-release $m.tar.bz2 )
6034 If the top level source directory does not have @file{src-release}
6035 (@value{GDBN} version 5.3.1 or earlier), try these commands instead:
6038 $ for m in gdb insight
6040 ( cd $m/src && gmake -f Makefile.in $m.tar )
6042 $ ( m=dejagnu; cd $m/src && gmake -f Makefile.in $m.tar.bz2 )
6045 @subsubheading Check the source files
6047 You're looking for files that have mysteriously disappeared.
6048 @kbd{distclean} has the habit of deleting files it shouldn't. Watch out
6049 for the @file{version.in} update @kbd{cronjob}.
6052 $ ( cd gdb/src && cvs -f -q -n update )
6056 @dots{} lots of generated files @dots{}
6061 @dots{} lots of generated files @dots{}
6066 @emph{Don't worry about the @file{gdb.info-??} or
6067 @file{gdb/p-exp.tab.c}. They were generated (and yes @file{gdb.info-1}
6068 was also generated only something strange with CVS means that they
6069 didn't get supressed). Fixing it would be nice though.}
6071 @subsubheading Create compressed versions of the release
6077 dejagnu/ dejagnu-gdb-5.2.tar.bz2 gdb/ gdb-5.2.tar insight/ insight-5.2.tar
6078 $ for m in gdb insight
6080 bzip2 -v -9 -c $m-$v.tar > $m-$v.tar.bz2
6081 gzip -v -9 -c $m-$v.tar > $m-$v.tar.gz
6091 A pipe such as @kbd{bunzip2 < xxx.bz2 | gzip -9 > xxx.gz} is not since,
6092 in that mode, @code{gzip} does not know the name of the file and, hence,
6093 can not include it in the compressed file. This is also why the release
6094 process runs @code{tar} and @code{bzip2} as separate passes.
6097 @subsection Sanity check the tar ball
6099 Pick a popular machine (Solaris/PPC?) and try the build on that.
6102 $ bunzip2 < gdb-5.2.tar.bz2 | tar xpf -
6107 $ ./gdb/gdb ./gdb/gdb
6111 Breakpoint 1 at 0x80732bc: file main.c, line 734.
6113 Starting program: /tmp/gdb-5.2/gdb/gdb
6115 Breakpoint 1, main (argc=1, argv=0xbffff8b4) at main.c:734
6116 734 catch_errors (captured_main, &args, "", RETURN_MASK_ALL);
6118 $1 = @{argc = 136426532, argv = 0x821b7f0@}
6122 @subsection Make a release candidate available
6124 If this is a release candidate then the only remaining steps are:
6128 Commit @file{version.in} and @file{ChangeLog}
6130 Tweak @file{version.in} (and @file{ChangeLog} to read
6131 @var{L}.@var{M}.@var{N}-0000-00-00-cvs so that the version update
6132 process can restart.
6134 Make the release candidate available in
6135 @uref{ftp://sources.redhat.com/pub/gdb/snapshots/branch}
6137 Notify the relevant mailing lists ( @email{gdb@@sources.redhat.com} and
6138 @email{gdb-testers@@sources.redhat.com} that the candidate is available.
6141 @subsection Make a formal release available
6143 (And you thought all that was required was to post an e-mail.)
6145 @subsubheading Install on sware
6147 Copy the new files to both the release and the old release directory:
6150 $ cp *.bz2 *.gz ~ftp/pub/gdb/old-releases/
6151 $ cp *.bz2 *.gz ~ftp/pub/gdb/releases
6155 Clean up the releases directory so that only the most recent releases
6156 are available (e.g. keep 5.2 and 5.2.1 but remove 5.1):
6159 $ cd ~ftp/pub/gdb/releases
6164 Update the file @file{README} and @file{.message} in the releases
6171 $ ln README .message
6174 @subsubheading Update the web pages.
6178 @item htdocs/download/ANNOUNCEMENT
6179 This file, which is posted as the official announcement, includes:
6182 General announcement
6184 News. If making an @var{M}.@var{N}.1 release, retain the news from
6185 earlier @var{M}.@var{N} release.
6190 @item htdocs/index.html
6191 @itemx htdocs/news/index.html
6192 @itemx htdocs/download/index.html
6193 These files include:
6196 announcement of the most recent release
6198 news entry (remember to update both the top level and the news directory).
6200 These pages also need to be regenerate using @code{index.sh}.
6202 @item download/onlinedocs/
6203 You need to find the magic command that is used to generate the online
6204 docs from the @file{.tar.bz2}. The best way is to look in the output
6205 from one of the nightly @code{cron} jobs and then just edit accordingly.
6209 $ ~/ss/update-web-docs \
6210 ~ftp/pub/gdb/releases/gdb-5.2.tar.bz2 \
6212 /www/sourceware/htdocs/gdb/download/onlinedocs \
6217 Just like the online documentation. Something like:
6220 $ /bin/sh ~/ss/update-web-ari \
6221 ~ftp/pub/gdb/releases/gdb-5.2.tar.bz2 \
6223 /www/sourceware/htdocs/gdb/download/ari \
6229 @subsubheading Shadow the pages onto gnu
6231 Something goes here.
6234 @subsubheading Install the @value{GDBN} tar ball on GNU
6236 At the time of writing, the GNU machine was @kbd{gnudist.gnu.org} in
6237 @file{~ftp/gnu/gdb}.
6239 @subsubheading Make the @file{ANNOUNCEMENT}
6241 Post the @file{ANNOUNCEMENT} file you created above to:
6245 @email{gdb-announce@@sources.redhat.com, GDB Announcement mailing list}
6247 @email{info-gnu@@gnu.org, General GNU Announcement list} (but delay it a
6248 day or so to let things get out)
6250 @email{bug-gdb@@gnu.org, GDB Bug Report mailing list}
6255 The release is out but you're still not finished.
6257 @subsubheading Commit outstanding changes
6259 In particular you'll need to commit any changes to:
6263 @file{gdb/ChangeLog}
6265 @file{gdb/version.in}
6272 @subsubheading Tag the release
6277 $ d=`date -u +%Y-%m-%d`
6280 $ ( cd insight/src/gdb && cvs -f -q update )
6281 $ ( cd insight/src && cvs -f -q tag gdb_5_2-$d-release )
6284 Insight is used since that contains more of the release than
6285 @value{GDBN} (@code{dejagnu} doesn't get tagged but I think we can live
6288 @subsubheading Mention the release on the trunk
6290 Just put something in the @file{ChangeLog} so that the trunk also
6291 indicates when the release was made.
6293 @subsubheading Restart @file{gdb/version.in}
6295 If @file{gdb/version.in} does not contain an ISO date such as
6296 @kbd{2002-01-24} then the daily @code{cronjob} won't update it. Having
6297 committed all the release changes it can be set to
6298 @file{5.2.0_0000-00-00-cvs} which will restart things (yes the @kbd{_}
6299 is important - it affects the snapshot process).
6301 Don't forget the @file{ChangeLog}.
6303 @subsubheading Merge into trunk
6305 The files committed to the branch may also need changes merged into the
6308 @subsubheading Revise the release schedule
6310 Post a revised release schedule to @email{gdb@@sources.redhat.com, GDB
6311 Discussion List} with an updated announcement. The schedule can be
6312 generated by running:
6315 $ ~/ss/schedule `date +%s` schedule
6319 The first parameter is approximate date/time in seconds (from the epoch)
6320 of the most recent release.
6322 Also update the schedule @code{cronjob}.
6324 @section Post release
6326 Remove any @code{OBSOLETE} code.
6333 The testsuite is an important component of the @value{GDBN} package.
6334 While it is always worthwhile to encourage user testing, in practice
6335 this is rarely sufficient; users typically use only a small subset of
6336 the available commands, and it has proven all too common for a change
6337 to cause a significant regression that went unnoticed for some time.
6339 The @value{GDBN} testsuite uses the DejaGNU testing framework.
6340 DejaGNU is built using @code{Tcl} and @code{expect}. The tests
6341 themselves are calls to various @code{Tcl} procs; the framework runs all the
6342 procs and summarizes the passes and fails.
6344 @section Using the Testsuite
6346 @cindex running the test suite
6347 To run the testsuite, simply go to the @value{GDBN} object directory (or to the
6348 testsuite's objdir) and type @code{make check}. This just sets up some
6349 environment variables and invokes DejaGNU's @code{runtest} script. While
6350 the testsuite is running, you'll get mentions of which test file is in use,
6351 and a mention of any unexpected passes or fails. When the testsuite is
6352 finished, you'll get a summary that looks like this:
6357 # of expected passes 6016
6358 # of unexpected failures 58
6359 # of unexpected successes 5
6360 # of expected failures 183
6361 # of unresolved testcases 3
6362 # of untested testcases 5
6365 The ideal test run consists of expected passes only; however, reality
6366 conspires to keep us from this ideal. Unexpected failures indicate
6367 real problems, whether in @value{GDBN} or in the testsuite. Expected
6368 failures are still failures, but ones which have been decided are too
6369 hard to deal with at the time; for instance, a test case might work
6370 everywhere except on AIX, and there is no prospect of the AIX case
6371 being fixed in the near future. Expected failures should not be added
6372 lightly, since you may be masking serious bugs in @value{GDBN}.
6373 Unexpected successes are expected fails that are passing for some
6374 reason, while unresolved and untested cases often indicate some minor
6375 catastrophe, such as the compiler being unable to deal with a test
6378 When making any significant change to @value{GDBN}, you should run the
6379 testsuite before and after the change, to confirm that there are no
6380 regressions. Note that truly complete testing would require that you
6381 run the testsuite with all supported configurations and a variety of
6382 compilers; however this is more than really necessary. In many cases
6383 testing with a single configuration is sufficient. Other useful
6384 options are to test one big-endian (Sparc) and one little-endian (x86)
6385 host, a cross config with a builtin simulator (powerpc-eabi,
6386 mips-elf), or a 64-bit host (Alpha).
6388 If you add new functionality to @value{GDBN}, please consider adding
6389 tests for it as well; this way future @value{GDBN} hackers can detect
6390 and fix their changes that break the functionality you added.
6391 Similarly, if you fix a bug that was not previously reported as a test
6392 failure, please add a test case for it. Some cases are extremely
6393 difficult to test, such as code that handles host OS failures or bugs
6394 in particular versions of compilers, and it's OK not to try to write
6395 tests for all of those.
6397 @section Testsuite Organization
6399 @cindex test suite organization
6400 The testsuite is entirely contained in @file{gdb/testsuite}. While the
6401 testsuite includes some makefiles and configury, these are very minimal,
6402 and used for little besides cleaning up, since the tests themselves
6403 handle the compilation of the programs that @value{GDBN} will run. The file
6404 @file{testsuite/lib/gdb.exp} contains common utility procs useful for
6405 all @value{GDBN} tests, while the directory @file{testsuite/config} contains
6406 configuration-specific files, typically used for special-purpose
6407 definitions of procs like @code{gdb_load} and @code{gdb_start}.
6409 The tests themselves are to be found in @file{testsuite/gdb.*} and
6410 subdirectories of those. The names of the test files must always end
6411 with @file{.exp}. DejaGNU collects the test files by wildcarding
6412 in the test directories, so both subdirectories and individual files
6413 get chosen and run in alphabetical order.
6415 The following table lists the main types of subdirectories and what they
6416 are for. Since DejaGNU finds test files no matter where they are
6417 located, and since each test file sets up its own compilation and
6418 execution environment, this organization is simply for convenience and
6423 This is the base testsuite. The tests in it should apply to all
6424 configurations of @value{GDBN} (but generic native-only tests may live here).
6425 The test programs should be in the subset of C that is valid K&R,
6426 ANSI/ISO, and C++ (@code{#ifdef}s are allowed if necessary, for instance
6429 @item gdb.@var{lang}
6430 Language-specific tests for any language @var{lang} besides C. Examples are
6431 @file{gdb.cp} and @file{gdb.java}.
6433 @item gdb.@var{platform}
6434 Non-portable tests. The tests are specific to a specific configuration
6435 (host or target), such as HP-UX or eCos. Example is @file{gdb.hp}, for
6438 @item gdb.@var{compiler}
6439 Tests specific to a particular compiler. As of this writing (June
6440 1999), there aren't currently any groups of tests in this category that
6441 couldn't just as sensibly be made platform-specific, but one could
6442 imagine a @file{gdb.gcc}, for tests of @value{GDBN}'s handling of GCC
6445 @item gdb.@var{subsystem}
6446 Tests that exercise a specific @value{GDBN} subsystem in more depth. For
6447 instance, @file{gdb.disasm} exercises various disassemblers, while
6448 @file{gdb.stabs} tests pathways through the stabs symbol reader.
6451 @section Writing Tests
6452 @cindex writing tests
6454 In many areas, the @value{GDBN} tests are already quite comprehensive; you
6455 should be able to copy existing tests to handle new cases.
6457 You should try to use @code{gdb_test} whenever possible, since it
6458 includes cases to handle all the unexpected errors that might happen.
6459 However, it doesn't cost anything to add new test procedures; for
6460 instance, @file{gdb.base/exprs.exp} defines a @code{test_expr} that
6461 calls @code{gdb_test} multiple times.
6463 Only use @code{send_gdb} and @code{gdb_expect} when absolutely
6464 necessary, such as when @value{GDBN} has several valid responses to a command.
6466 The source language programs do @emph{not} need to be in a consistent
6467 style. Since @value{GDBN} is used to debug programs written in many different
6468 styles, it's worth having a mix of styles in the testsuite; for
6469 instance, some @value{GDBN} bugs involving the display of source lines would
6470 never manifest themselves if the programs used GNU coding style
6477 Check the @file{README} file, it often has useful information that does not
6478 appear anywhere else in the directory.
6481 * Getting Started:: Getting started working on @value{GDBN}
6482 * Debugging GDB:: Debugging @value{GDBN} with itself
6485 @node Getting Started,,, Hints
6487 @section Getting Started
6489 @value{GDBN} is a large and complicated program, and if you first starting to
6490 work on it, it can be hard to know where to start. Fortunately, if you
6491 know how to go about it, there are ways to figure out what is going on.
6493 This manual, the @value{GDBN} Internals manual, has information which applies
6494 generally to many parts of @value{GDBN}.
6496 Information about particular functions or data structures are located in
6497 comments with those functions or data structures. If you run across a
6498 function or a global variable which does not have a comment correctly
6499 explaining what is does, this can be thought of as a bug in @value{GDBN}; feel
6500 free to submit a bug report, with a suggested comment if you can figure
6501 out what the comment should say. If you find a comment which is
6502 actually wrong, be especially sure to report that.
6504 Comments explaining the function of macros defined in host, target, or
6505 native dependent files can be in several places. Sometimes they are
6506 repeated every place the macro is defined. Sometimes they are where the
6507 macro is used. Sometimes there is a header file which supplies a
6508 default definition of the macro, and the comment is there. This manual
6509 also documents all the available macros.
6510 @c (@pxref{Host Conditionals}, @pxref{Target
6511 @c Conditionals}, @pxref{Native Conditionals}, and @pxref{Obsolete
6514 Start with the header files. Once you have some idea of how
6515 @value{GDBN}'s internal symbol tables are stored (see @file{symtab.h},
6516 @file{gdbtypes.h}), you will find it much easier to understand the
6517 code which uses and creates those symbol tables.
6519 You may wish to process the information you are getting somehow, to
6520 enhance your understanding of it. Summarize it, translate it to another
6521 language, add some (perhaps trivial or non-useful) feature to @value{GDBN}, use
6522 the code to predict what a test case would do and write the test case
6523 and verify your prediction, etc. If you are reading code and your eyes
6524 are starting to glaze over, this is a sign you need to use a more active
6527 Once you have a part of @value{GDBN} to start with, you can find more
6528 specifically the part you are looking for by stepping through each
6529 function with the @code{next} command. Do not use @code{step} or you
6530 will quickly get distracted; when the function you are stepping through
6531 calls another function try only to get a big-picture understanding
6532 (perhaps using the comment at the beginning of the function being
6533 called) of what it does. This way you can identify which of the
6534 functions being called by the function you are stepping through is the
6535 one which you are interested in. You may need to examine the data
6536 structures generated at each stage, with reference to the comments in
6537 the header files explaining what the data structures are supposed to
6540 Of course, this same technique can be used if you are just reading the
6541 code, rather than actually stepping through it. The same general
6542 principle applies---when the code you are looking at calls something
6543 else, just try to understand generally what the code being called does,
6544 rather than worrying about all its details.
6546 @cindex command implementation
6547 A good place to start when tracking down some particular area is with
6548 a command which invokes that feature. Suppose you want to know how
6549 single-stepping works. As a @value{GDBN} user, you know that the
6550 @code{step} command invokes single-stepping. The command is invoked
6551 via command tables (see @file{command.h}); by convention the function
6552 which actually performs the command is formed by taking the name of
6553 the command and adding @samp{_command}, or in the case of an
6554 @code{info} subcommand, @samp{_info}. For example, the @code{step}
6555 command invokes the @code{step_command} function and the @code{info
6556 display} command invokes @code{display_info}. When this convention is
6557 not followed, you might have to use @code{grep} or @kbd{M-x
6558 tags-search} in emacs, or run @value{GDBN} on itself and set a
6559 breakpoint in @code{execute_command}.
6561 @cindex @code{bug-gdb} mailing list
6562 If all of the above fail, it may be appropriate to ask for information
6563 on @code{bug-gdb}. But @emph{never} post a generic question like ``I was
6564 wondering if anyone could give me some tips about understanding
6565 @value{GDBN}''---if we had some magic secret we would put it in this manual.
6566 Suggestions for improving the manual are always welcome, of course.
6568 @node Debugging GDB,,,Hints
6570 @section Debugging @value{GDBN} with itself
6571 @cindex debugging @value{GDBN}
6573 If @value{GDBN} is limping on your machine, this is the preferred way to get it
6574 fully functional. Be warned that in some ancient Unix systems, like
6575 Ultrix 4.2, a program can't be running in one process while it is being
6576 debugged in another. Rather than typing the command @kbd{@w{./gdb
6577 ./gdb}}, which works on Suns and such, you can copy @file{gdb} to
6578 @file{gdb2} and then type @kbd{@w{./gdb ./gdb2}}.
6580 When you run @value{GDBN} in the @value{GDBN} source directory, it will read a
6581 @file{.gdbinit} file that sets up some simple things to make debugging
6582 gdb easier. The @code{info} command, when executed without a subcommand
6583 in a @value{GDBN} being debugged by gdb, will pop you back up to the top level
6584 gdb. See @file{.gdbinit} for details.
6586 If you use emacs, you will probably want to do a @code{make TAGS} after
6587 you configure your distribution; this will put the machine dependent
6588 routines for your local machine where they will be accessed first by
6591 Also, make sure that you've either compiled @value{GDBN} with your local cc, or
6592 have run @code{fixincludes} if you are compiling with gcc.
6594 @section Submitting Patches
6596 @cindex submitting patches
6597 Thanks for thinking of offering your changes back to the community of
6598 @value{GDBN} users. In general we like to get well designed enhancements.
6599 Thanks also for checking in advance about the best way to transfer the
6602 The @value{GDBN} maintainers will only install ``cleanly designed'' patches.
6603 This manual summarizes what we believe to be clean design for @value{GDBN}.
6605 If the maintainers don't have time to put the patch in when it arrives,
6606 or if there is any question about a patch, it goes into a large queue
6607 with everyone else's patches and bug reports.
6609 @cindex legal papers for code contributions
6610 The legal issue is that to incorporate substantial changes requires a
6611 copyright assignment from you and/or your employer, granting ownership
6612 of the changes to the Free Software Foundation. You can get the
6613 standard documents for doing this by sending mail to @code{gnu@@gnu.org}
6614 and asking for it. We recommend that people write in "All programs
6615 owned by the Free Software Foundation" as "NAME OF PROGRAM", so that
6616 changes in many programs (not just @value{GDBN}, but GAS, Emacs, GCC,
6618 contributed with only one piece of legalese pushed through the
6619 bureaucracy and filed with the FSF. We can't start merging changes until
6620 this paperwork is received by the FSF (their rules, which we follow
6621 since we maintain it for them).
6623 Technically, the easiest way to receive changes is to receive each
6624 feature as a small context diff or unidiff, suitable for @code{patch}.
6625 Each message sent to me should include the changes to C code and
6626 header files for a single feature, plus @file{ChangeLog} entries for
6627 each directory where files were modified, and diffs for any changes
6628 needed to the manuals (@file{gdb/doc/gdb.texinfo} or
6629 @file{gdb/doc/gdbint.texinfo}). If there are a lot of changes for a
6630 single feature, they can be split down into multiple messages.
6632 In this way, if we read and like the feature, we can add it to the
6633 sources with a single patch command, do some testing, and check it in.
6634 If you leave out the @file{ChangeLog}, we have to write one. If you leave
6635 out the doc, we have to puzzle out what needs documenting. Etc., etc.
6637 The reason to send each change in a separate message is that we will not
6638 install some of the changes. They'll be returned to you with questions
6639 or comments. If we're doing our job correctly, the message back to you
6640 will say what you have to fix in order to make the change acceptable.
6641 The reason to have separate messages for separate features is so that
6642 the acceptable changes can be installed while one or more changes are
6643 being reworked. If multiple features are sent in a single message, we
6644 tend to not put in the effort to sort out the acceptable changes from
6645 the unacceptable, so none of the features get installed until all are
6648 If this sounds painful or authoritarian, well, it is. But we get a lot
6649 of bug reports and a lot of patches, and many of them don't get
6650 installed because we don't have the time to finish the job that the bug
6651 reporter or the contributor could have done. Patches that arrive
6652 complete, working, and well designed, tend to get installed on the day
6653 they arrive. The others go into a queue and get installed as time
6654 permits, which, since the maintainers have many demands to meet, may not
6655 be for quite some time.
6657 Please send patches directly to
6658 @email{gdb-patches@@sources.redhat.com, the @value{GDBN} maintainers}.
6660 @section Obsolete Conditionals
6661 @cindex obsolete code
6663 Fragments of old code in @value{GDBN} sometimes reference or set the following
6664 configuration macros. They should not be used by new code, and old uses
6665 should be removed as those parts of the debugger are otherwise touched.
6668 @item STACK_END_ADDR
6669 This macro used to define where the end of the stack appeared, for use
6670 in interpreting core file formats that don't record this address in the
6671 core file itself. This information is now configured in BFD, and @value{GDBN}
6672 gets the info portably from there. The values in @value{GDBN}'s configuration
6673 files should be moved into BFD configuration files (if needed there),
6674 and deleted from all of @value{GDBN}'s config files.
6676 Any @file{@var{foo}-xdep.c} file that references STACK_END_ADDR
6677 is so old that it has never been converted to use BFD. Now that's old!
6681 @include observer.texi