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9742079a | 1 | \input texinfo @c -*- texinfo -*- |
c906108c | 2 | @setfilename gdbint.info |
25822942 | 3 | @include gdb-cfg.texi |
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4 | @dircategory Programming & development tools. |
5 | @direntry | |
c906108c | 6 | * Gdb-Internals: (gdbint). The GNU debugger's internals. |
e9c75b65 | 7 | @end direntry |
c906108c SS |
8 | |
9 | @ifinfo | |
25822942 | 10 | This file documents the internals of the GNU debugger @value{GDBN}. |
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11 | Copyright 1990,1991,1992,1993,1994,1996,1998,1999,2000,2001 |
12 | Free Software Foundation, Inc. | |
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13 | Contributed by Cygnus Solutions. Written by John Gilmore. |
14 | Second Edition by Stan Shebs. | |
15 | ||
e9c75b65 EZ |
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 the | |
19 | Invariant Sections being ``Algorithms'' and ``Porting GDB'', with the | |
20 | Front-Cover texts being ``A GNU Manual,'' and with the Back-Cover | |
21 | Texts as in (a) below. | |
c906108c | 22 | |
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23 | (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify |
24 | this GNU Manual, like GNU software. Copies published by the Free | |
25 | Software Foundation raise funds for GNU development.'' | |
c906108c SS |
26 | @end ifinfo |
27 | ||
28 | @setchapternewpage off | |
25822942 | 29 | @settitle @value{GDBN} Internals |
c906108c | 30 | |
56caf160 EZ |
31 | @syncodeindex fn cp |
32 | @syncodeindex vr cp | |
33 | ||
c906108c | 34 | @titlepage |
25822942 | 35 | @title @value{GDBN} Internals |
c906108c SS |
36 | @subtitle{A guide to the internals of the GNU debugger} |
37 | @author John Gilmore | |
38 | @author Cygnus Solutions | |
39 | @author Second Edition: | |
40 | @author Stan Shebs | |
41 | @author Cygnus Solutions | |
42 | @page | |
43 | @tex | |
44 | \def\$#1${{#1}} % Kluge: collect RCS revision info without $...$ | |
45 | \xdef\manvers{\$Revision$} % For use in headers, footers too | |
46 | {\parskip=0pt | |
47 | \hfill Cygnus Solutions\par | |
48 | \hfill \manvers\par | |
49 | \hfill \TeX{}info \texinfoversion\par | |
50 | } | |
51 | @end tex | |
52 | ||
53 | @vskip 0pt plus 1filll | |
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54 | Copyright @copyright{} 1990,1991,1992,1993,1994,1996,1998,1999,2000,2001 |
55 | Free Software Foundation, Inc. | |
c906108c | 56 | |
e9c75b65 EZ |
57 | Permission is granted to copy, distribute and/or modify this document |
58 | under the terms of the GNU Free Documentation License, Version 1.1 or | |
59 | any later version published by the Free Software Foundation; with the | |
60 | Invariant Sections being ``Algorithms'' and ``Porting GDB'', with the | |
61 | Front-Cover texts being ``A GNU Manual,'' and with the Back-Cover | |
62 | Texts as in (a) below. | |
c906108c | 63 | |
e9c75b65 EZ |
64 | (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify |
65 | this GNU Manual, like GNU software. Copies published by the Free | |
66 | Software Foundation raise funds for GNU development.'' | |
c906108c SS |
67 | @end titlepage |
68 | ||
449f3b6c AC |
69 | @c TeX can handle the contents at the start but makeinfo 3.12 can not |
70 | @iftex | |
71 | @contents | |
72 | @end iftex | |
73 | ||
c906108c SS |
74 | @node Top |
75 | @c Perhaps this should be the title of the document (but only for info, | |
76 | @c not for TeX). Existing GNU manuals seem inconsistent on this point. | |
77 | @top Scope of this Document | |
78 | ||
25822942 DB |
79 | This document documents the internals of the GNU debugger, @value{GDBN}. It |
80 | includes description of @value{GDBN}'s key algorithms and operations, as well | |
81 | as the mechanisms that adapt @value{GDBN} to specific hosts and targets. | |
c906108c SS |
82 | |
83 | @menu | |
84 | * Requirements:: | |
85 | * Overall Structure:: | |
86 | * Algorithms:: | |
87 | * User Interface:: | |
89437448 | 88 | * libgdb:: |
c906108c SS |
89 | * Symbol Handling:: |
90 | * Language Support:: | |
91 | * Host Definition:: | |
92 | * Target Architecture Definition:: | |
93 | * Target Vector Definition:: | |
94 | * Native Debugging:: | |
95 | * Support Libraries:: | |
96 | * Coding:: | |
97 | * Porting GDB:: | |
085dd6e6 | 98 | * Testsuite:: |
c906108c | 99 | * Hints:: |
56caf160 | 100 | * Index:: |
c906108c SS |
101 | @end menu |
102 | ||
103 | @node Requirements | |
104 | ||
105 | @chapter Requirements | |
56caf160 | 106 | @cindex requirements for @value{GDBN} |
c906108c SS |
107 | |
108 | Before diving into the internals, you should understand the formal | |
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109 | requirements and other expectations for @value{GDBN}. Although some |
110 | of these may seem obvious, there have been proposals for @value{GDBN} | |
111 | that have run counter to these requirements. | |
c906108c | 112 | |
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113 | First of all, @value{GDBN} is a debugger. It's not designed to be a |
114 | front panel for embedded systems. It's not a text editor. It's not a | |
115 | shell. It's not a programming environment. | |
c906108c | 116 | |
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117 | @value{GDBN} is an interactive tool. Although a batch mode is |
118 | available, @value{GDBN}'s primary role is to interact with a human | |
119 | programmer. | |
c906108c | 120 | |
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121 | @value{GDBN} should be responsive to the user. A programmer hot on |
122 | the trail of a nasty bug, and operating under a looming deadline, is | |
123 | going to be very impatient of everything, including the response time | |
124 | to debugger commands. | |
c906108c | 125 | |
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126 | @value{GDBN} should be relatively permissive, such as for expressions. |
127 | While the compiler should be picky (or have the option to be made | |
be9c6c35 | 128 | picky), since source code lives for a long time usually, the |
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129 | programmer doing debugging shouldn't be spending time figuring out to |
130 | mollify the debugger. | |
c906108c | 131 | |
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132 | @value{GDBN} will be called upon to deal with really large programs. |
133 | Executable sizes of 50 to 100 megabytes occur regularly, and we've | |
134 | heard reports of programs approaching 1 gigabyte in size. | |
c906108c | 135 | |
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136 | @value{GDBN} should be able to run everywhere. No other debugger is |
137 | available for even half as many configurations as @value{GDBN} | |
138 | supports. | |
c906108c SS |
139 | |
140 | ||
141 | @node Overall Structure | |
142 | ||
143 | @chapter Overall Structure | |
144 | ||
56caf160 EZ |
145 | @value{GDBN} consists of three major subsystems: user interface, |
146 | symbol handling (the @dfn{symbol side}), and target system handling (the | |
147 | @dfn{target side}). | |
c906108c | 148 | |
2e685b93 | 149 | The user interface consists of several actual interfaces, plus |
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150 | supporting code. |
151 | ||
152 | The symbol side consists of object file readers, debugging info | |
153 | interpreters, symbol table management, source language expression | |
154 | parsing, type and value printing. | |
155 | ||
156 | The target side consists of execution control, stack frame analysis, and | |
157 | physical target manipulation. | |
158 | ||
159 | The target side/symbol side division is not formal, and there are a | |
160 | number of exceptions. For instance, core file support involves symbolic | |
161 | elements (the basic core file reader is in BFD) and target elements (it | |
162 | supplies the contents of memory and the values of registers). Instead, | |
163 | this division is useful for understanding how the minor subsystems | |
164 | should fit together. | |
165 | ||
166 | @section The Symbol Side | |
167 | ||
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168 | The symbolic side of @value{GDBN} can be thought of as ``everything |
169 | you can do in @value{GDBN} without having a live program running''. | |
170 | For instance, you can look at the types of variables, and evaluate | |
171 | many kinds of expressions. | |
c906108c SS |
172 | |
173 | @section The Target Side | |
174 | ||
56caf160 EZ |
175 | The target side of @value{GDBN} is the ``bits and bytes manipulator''. |
176 | Although it may make reference to symbolic info here and there, most | |
177 | of the target side will run with only a stripped executable | |
178 | available---or even no executable at all, in remote debugging cases. | |
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179 | |
180 | Operations such as disassembly, stack frame crawls, and register | |
181 | display, are able to work with no symbolic info at all. In some cases, | |
25822942 | 182 | such as disassembly, @value{GDBN} will use symbolic info to present addresses |
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183 | relative to symbols rather than as raw numbers, but it will work either |
184 | way. | |
185 | ||
186 | @section Configurations | |
187 | ||
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188 | @cindex host |
189 | @cindex target | |
25822942 | 190 | @dfn{Host} refers to attributes of the system where @value{GDBN} runs. |
c906108c SS |
191 | @dfn{Target} refers to the system where the program being debugged |
192 | executes. In most cases they are the same machine, in which case a | |
193 | third type of @dfn{Native} attributes come into play. | |
194 | ||
195 | Defines and include files needed to build on the host are host support. | |
196 | Examples are tty support, system defined types, host byte order, host | |
197 | float format. | |
198 | ||
199 | Defines and information needed to handle the target format are target | |
200 | dependent. Examples are the stack frame format, instruction set, | |
201 | breakpoint instruction, registers, and how to set up and tear down the stack | |
202 | to call a function. | |
203 | ||
204 | Information that is only needed when the host and target are the same, | |
205 | is native dependent. One example is Unix child process support; if the | |
206 | host and target are not the same, doing a fork to start the target | |
207 | process is a bad idea. The various macros needed for finding the | |
208 | registers in the @code{upage}, running @code{ptrace}, and such are all | |
209 | in the native-dependent files. | |
210 | ||
211 | Another example of native-dependent code is support for features that | |
212 | are really part of the target environment, but which require | |
213 | @code{#include} files that are only available on the host system. Core | |
214 | file handling and @code{setjmp} handling are two common cases. | |
215 | ||
25822942 | 216 | When you want to make @value{GDBN} work ``native'' on a particular machine, you |
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217 | have to include all three kinds of information. |
218 | ||
219 | ||
220 | @node Algorithms | |
221 | ||
222 | @chapter Algorithms | |
56caf160 | 223 | @cindex algorithms |
c906108c | 224 | |
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225 | @value{GDBN} uses a number of debugging-specific algorithms. They are |
226 | often not very complicated, but get lost in the thicket of special | |
227 | cases and real-world issues. This chapter describes the basic | |
228 | algorithms and mentions some of the specific target definitions that | |
229 | they use. | |
c906108c SS |
230 | |
231 | @section Frames | |
232 | ||
56caf160 EZ |
233 | @cindex frame |
234 | @cindex call stack frame | |
235 | A frame is a construct that @value{GDBN} uses to keep track of calling | |
236 | and called functions. | |
c906108c | 237 | |
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238 | @findex create_new_frame |
239 | @vindex FRAME_FP | |
c906108c | 240 | @code{FRAME_FP} in the machine description has no meaning to the |
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241 | machine-independent part of @value{GDBN}, except that it is used when |
242 | setting up a new frame from scratch, as follows: | |
c906108c SS |
243 | |
244 | @example | |
245 | create_new_frame (read_register (FP_REGNUM), read_pc ())); | |
246 | @end example | |
247 | ||
56caf160 | 248 | @cindex frame pointer register |
c906108c SS |
249 | Other than that, all the meaning imparted to @code{FP_REGNUM} is |
250 | imparted by the machine-dependent code. So, @code{FP_REGNUM} can have | |
251 | any value that is convenient for the code that creates new frames. | |
252 | (@code{create_new_frame} calls @code{INIT_EXTRA_FRAME_INFO} if it is | |
253 | defined; that is where you should use the @code{FP_REGNUM} value, if | |
254 | your frames are nonstandard.) | |
255 | ||
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256 | @cindex frame chain |
257 | Given a @value{GDBN} frame, define @code{FRAME_CHAIN} to determine the | |
258 | address of the calling function's frame. This will be used to create | |
259 | a new @value{GDBN} frame struct, and then @code{INIT_EXTRA_FRAME_INFO} | |
260 | and @code{INIT_FRAME_PC} will be called for the new frame. | |
c906108c SS |
261 | |
262 | @section Breakpoint Handling | |
263 | ||
56caf160 | 264 | @cindex breakpoints |
c906108c SS |
265 | In general, a breakpoint is a user-designated location in the program |
266 | where the user wants to regain control if program execution ever reaches | |
267 | that location. | |
268 | ||
269 | There are two main ways to implement breakpoints; either as ``hardware'' | |
270 | breakpoints or as ``software'' breakpoints. | |
271 | ||
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272 | @cindex hardware breakpoints |
273 | @cindex program counter | |
c906108c SS |
274 | Hardware breakpoints are sometimes available as a builtin debugging |
275 | features with some chips. Typically these work by having dedicated | |
276 | register into which the breakpoint address may be stored. If the PC | |
56caf160 | 277 | (shorthand for @dfn{program counter}) |
c906108c | 278 | ever matches a value in a breakpoint registers, the CPU raises an |
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279 | exception and reports it to @value{GDBN}. |
280 | ||
281 | Another possibility is when an emulator is in use; many emulators | |
282 | include circuitry that watches the address lines coming out from the | |
283 | processor, and force it to stop if the address matches a breakpoint's | |
284 | address. | |
285 | ||
286 | A third possibility is that the target already has the ability to do | |
287 | breakpoints somehow; for instance, a ROM monitor may do its own | |
288 | software breakpoints. So although these are not literally ``hardware | |
289 | breakpoints'', from @value{GDBN}'s point of view they work the same; | |
290 | @value{GDBN} need not do nothing more than set the breakpoint and wait | |
291 | for something to happen. | |
c906108c SS |
292 | |
293 | Since they depend on hardware resources, hardware breakpoints may be | |
56caf160 | 294 | limited in number; when the user asks for more, @value{GDBN} will |
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295 | start trying to set software breakpoints. (On some architectures, |
296 | notably the 32-bit x86 platforms, @value{GDBN} cannot alsways know | |
297 | whether there's enough hardware resources to insert all the hardware | |
298 | breakpoints and watchpoints. On those platforms, @value{GDBN} prints | |
299 | an error message only when the program being debugged is continued.) | |
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300 | |
301 | @cindex software breakpoints | |
302 | Software breakpoints require @value{GDBN} to do somewhat more work. | |
303 | The basic theory is that @value{GDBN} will replace a program | |
304 | instruction with a trap, illegal divide, or some other instruction | |
305 | that will cause an exception, and then when it's encountered, | |
306 | @value{GDBN} will take the exception and stop the program. When the | |
307 | user says to continue, @value{GDBN} will restore the original | |
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308 | instruction, single-step, re-insert the trap, and continue on. |
309 | ||
310 | Since it literally overwrites the program being tested, the program area | |
be9c6c35 | 311 | must be writable, so this technique won't work on programs in ROM. It |
c906108c | 312 | can also distort the behavior of programs that examine themselves, |
56caf160 | 313 | although such a situation would be highly unusual. |
c906108c SS |
314 | |
315 | Also, the software breakpoint instruction should be the smallest size of | |
316 | instruction, so it doesn't overwrite an instruction that might be a jump | |
317 | target, and cause disaster when the program jumps into the middle of the | |
318 | breakpoint instruction. (Strictly speaking, the breakpoint must be no | |
319 | larger than the smallest interval between instructions that may be jump | |
320 | targets; perhaps there is an architecture where only even-numbered | |
321 | instructions may jumped to.) Note that it's possible for an instruction | |
322 | set not to have any instructions usable for a software breakpoint, | |
323 | although in practice only the ARC has failed to define such an | |
324 | instruction. | |
325 | ||
56caf160 | 326 | @findex BREAKPOINT |
c906108c SS |
327 | The basic definition of the software breakpoint is the macro |
328 | @code{BREAKPOINT}. | |
329 | ||
330 | Basic breakpoint object handling is in @file{breakpoint.c}. However, | |
331 | much of the interesting breakpoint action is in @file{infrun.c}. | |
332 | ||
333 | @section Single Stepping | |
334 | ||
335 | @section Signal Handling | |
336 | ||
337 | @section Thread Handling | |
338 | ||
339 | @section Inferior Function Calls | |
340 | ||
341 | @section Longjmp Support | |
342 | ||
56caf160 | 343 | @cindex @code{longjmp} debugging |
25822942 | 344 | @value{GDBN} has support for figuring out that the target is doing a |
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345 | @code{longjmp} and for stopping at the target of the jump, if we are |
346 | stepping. This is done with a few specialized internal breakpoints, | |
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347 | which are visible in the output of the @samp{maint info breakpoint} |
348 | command. | |
c906108c | 349 | |
56caf160 | 350 | @findex GET_LONGJMP_TARGET |
c906108c SS |
351 | To make this work, you need to define a macro called |
352 | @code{GET_LONGJMP_TARGET}, which will examine the @code{jmp_buf} | |
353 | structure and extract the longjmp target address. Since @code{jmp_buf} | |
354 | is target specific, you will need to define it in the appropriate | |
56caf160 | 355 | @file{tm-@var{target}.h} file. Look in @file{tm-sun4os4.h} and |
c906108c SS |
356 | @file{sparc-tdep.c} for examples of how to do this. |
357 | ||
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358 | @section Watchpoints |
359 | @cindex watchpoints | |
360 | ||
361 | Watchpoints are a special kind of breakpoints (@pxref{Algorithms, | |
362 | breakpoints}) which break when data is accessed rather than when some | |
363 | instruction is executed. When you have data which changes without | |
364 | your knowing what code does that, watchpoints are the silver bullet to | |
365 | hunt down and kill such bugs. | |
366 | ||
367 | @cindex hardware watchpoints | |
368 | @cindex software watchpoints | |
369 | Watchpoints can be either hardware-assisted or not; the latter type is | |
370 | known as ``software watchpoints.'' @value{GDBN} always uses | |
371 | hardware-assisted watchpoints if they are available, and falls back on | |
372 | software watchpoints otherwise. Typical situations where @value{GDBN} | |
373 | will use software watchpoints are: | |
374 | ||
375 | @itemize @bullet | |
376 | @item | |
377 | The watched memory region is too large for the underlying hardware | |
378 | watchpoint support. For example, each x86 debug register can watch up | |
379 | to 4 bytes of memory, so trying to watch data structures whose size is | |
380 | more than 16 bytes will cause @value{GDBN} to use software | |
381 | watchpoints. | |
382 | ||
383 | @item | |
384 | The value of the expression to be watched depends on data held in | |
385 | registers (as opposed to memory). | |
386 | ||
387 | @item | |
388 | Too many different watchpoints requested. (On some architectures, | |
389 | this situation is impossible to detect until the debugged program is | |
390 | resumed.) Note that x86 debug registers are used both for hardware | |
391 | breakpoints and for watchpoints, so setting too many hardware | |
392 | breakpoints might cause watchpoint insertion to fail. | |
393 | ||
394 | @item | |
395 | No hardware-assisted watchpoints provided by the target | |
396 | implementation. | |
397 | @end itemize | |
398 | ||
399 | Software watchpoints are very slow, since @value{GDBN} needs to | |
400 | single-step the program being debugged and test the value of the | |
401 | watched expression(s) after each instruction. The rest of this | |
402 | section is mostly irrelevant for software watchpoints. | |
403 | ||
404 | @value{GDBN} uses several macros and primitives to support hardware | |
405 | watchpoints: | |
406 | ||
407 | @table @code | |
408 | @findex TARGET_HAS_HARDWARE_WATCHPOINTS | |
409 | @item TARGET_HAS_HARDWARE_WATCHPOINTS | |
410 | If defined, the target supports hardware watchpoints. | |
411 | ||
412 | @findex TARGET_CAN_USE_HARDWARE_WATCHPOINT | |
413 | @item TARGET_CAN_USE_HARDWARE_WATCHPOINT (@var{type}, @var{count}, @var{other}) | |
414 | Return the number of hardware watchpoints of type @var{type} that are | |
415 | possible to be set. The value is positive if @var{count} watchpoints | |
416 | of this type can be set, zero if setting watchpoints of this type is | |
417 | not supported, and negative if @var{count} is more than the maximum | |
418 | number of watchpoints of type @var{type} that can be set. @var{other} | |
419 | is non-zero if other types of watchpoints are currently enabled (there | |
420 | are architectures which cannot set watchpoints of different types at | |
421 | the same time). | |
422 | ||
423 | @findex TARGET_REGION_OK_FOR_HW_WATCHPOINT | |
424 | @item TARGET_REGION_OK_FOR_HW_WATCHPOINT (@var{addr}, @var{len}) | |
425 | Return non-zero if hardware watchpoints can be used to watch a region | |
426 | whose address is @var{addr} and whose length in bytes is @var{len}. | |
427 | ||
428 | @findex TARGET_REGION_SIZE_OK_FOR_HW_WATCHPOINT | |
429 | @item TARGET_REGION_SIZE_OK_FOR_HW_WATCHPOINT (@var{size}) | |
430 | Return non-zero if hardware watchpoints can be used to watch a region | |
431 | whose size is @var{size}. @value{GDBN} only uses this macro as a | |
432 | fall-back, in case @code{TARGET_REGION_OK_FOR_HW_WATCHPOINT} is not | |
433 | defined. | |
434 | ||
435 | @findex TARGET_DISABLE_HW_WATCHPOINTS | |
436 | @item TARGET_DISABLE_HW_WATCHPOINTS (@var{pid}) | |
437 | Disables watchpoints in the process identified by @var{pid}. This is | |
438 | used, e.g., on HP-UX which provides operations to disable and enable | |
439 | the page-level memory protection that implements hardware watchpoints | |
440 | on that platform. | |
441 | ||
442 | @findex TARGET_ENABLE_HW_WATCHPOINTS | |
443 | @item TARGET_ENABLE_HW_WATCHPOINTS (@var{pid}) | |
444 | Enables watchpoints in the process identified by @var{pid}. This is | |
445 | used, e.g., on HP-UX which provides operations to disable and enable | |
446 | the page-level memory protection that implements hardware watchpoints | |
447 | on that platform. | |
448 | ||
9742079a EZ |
449 | @findex target_insert_watchpoint |
450 | @findex target_remove_watchpoint | |
451 | @item target_insert_watchpoint (@var{addr}, @var{len}, @var{type}) | |
452 | @itemx target_remove_watchpoint (@var{addr}, @var{len}, @var{type}) | |
453 | Insert or remove a hardware watchpoint starting at @var{addr}, for | |
454 | @var{len} bytes. @var{type} is the watchpoint type, one of the | |
455 | possible values of the enumerated data type @code{target_hw_bp_type}, | |
456 | defined by @file{breakpoint.h} as follows: | |
457 | ||
458 | @example | |
459 | enum target_hw_bp_type | |
460 | @{ | |
461 | hw_write = 0, /* Common (write) HW watchpoint */ | |
462 | hw_read = 1, /* Read HW watchpoint */ | |
463 | hw_access = 2, /* Access (read or write) HW watchpoint */ | |
464 | hw_execute = 3 /* Execute HW breakpoint */ | |
465 | @}; | |
466 | @end example | |
467 | ||
468 | @noindent | |
469 | These two macros should return 0 for success, non-zero for failure. | |
470 | ||
471 | @cindex insert or remove hardware breakpoint | |
472 | @findex target_remove_hw_breakpoint | |
473 | @findex target_insert_hw_breakpoint | |
474 | @item target_remove_hw_breakpoint (@var{addr}, @var{shadow}) | |
475 | @itemx target_insert_hw_breakpoint (@var{addr}, @var{shadow}) | |
476 | Insert or remove a hardware-assisted breakpoint at address @var{addr}. | |
477 | Returns zero for success, non-zero for failure. @var{shadow} is the | |
478 | real contents of the byte where the breakpoint has been inserted; it | |
479 | is generally not valid when hardware breakpoints are used, but since | |
480 | no other code touches these values, the implementations of the above | |
481 | two macros can use them for their internal purposes. | |
482 | ||
483 | @findex target_stopped_data_address | |
484 | @item target_stopped_data_address () | |
485 | If the inferior has some watchpoint that triggered, return the address | |
486 | associated with that watchpoint. Otherwise, return zero. | |
487 | ||
488 | @findex DECR_PC_AFTER_HW_BREAK | |
489 | @item DECR_PC_AFTER_HW_BREAK | |
490 | If defined, @value{GDBN} decrements the program counter by the value | |
491 | of @code{DECR_PC_AFTER_HW_BREAK} after a hardware break-point. This | |
492 | overrides the value of @code{DECR_PC_AFTER_BREAK} when a breakpoint | |
493 | that breaks is a hardware-assisted breakpoint. | |
494 | ||
495 | @findex HAVE_STEPPABLE_WATCHPOINT | |
496 | @item HAVE_STEPPABLE_WATCHPOINT | |
497 | If defined to a non-zero value, it is not necessary to disable a | |
498 | watchpoint to step over it. | |
499 | ||
500 | @findex HAVE_NONSTEPPABLE_WATCHPOINT | |
501 | @item HAVE_NONSTEPPABLE_WATCHPOINT | |
502 | If defined to a non-zero value, @value{GDBN} should disable a | |
503 | watchpoint to step the inferior over it. | |
504 | ||
505 | @findex HAVE_CONTINUABLE_WATCHPOINT | |
506 | @item HAVE_CONTINUABLE_WATCHPOINT | |
507 | If defined to a non-zero value, it is possible to continue the | |
508 | inferior after a watchpoint has been hit. | |
509 | ||
510 | @findex CANNOT_STEP_HW_WATCHPOINTS | |
511 | @item CANNOT_STEP_HW_WATCHPOINTS | |
512 | If this is defined to a non-zero value, @value{GDBN} will remove all | |
513 | watchpoints before stepping the inferior. | |
514 | ||
515 | @findex STOPPED_BY_WATCHPOINT | |
516 | @item STOPPED_BY_WATCHPOINT (@var{wait_status}) | |
517 | Return non-zero if stopped by a watchpoint. @var{wait_status} is of | |
518 | the type @code{struct target_waitstatus}, defined by @file{target.h}. | |
519 | @end table | |
520 | ||
521 | @subsection x86 Watchpoints | |
522 | @cindex x86 debug registers | |
523 | @cindex watchpoints, on x86 | |
524 | ||
525 | The 32-bit Intel x86 (a.k.a.@: ia32) processors feature special debug | |
526 | registers designed to facilitate debugging. @value{GDBN} provides a | |
527 | generic library of functions that x86-based ports can use to implement | |
528 | support for watchpoints and hardware-assisted breakpoints. This | |
529 | subsection documents the x86 watchpoint facilities in @value{GDBN}. | |
530 | ||
531 | To use the generic x86 watchpoint support, a port should do the | |
532 | following: | |
533 | ||
534 | @itemize @bullet | |
535 | @findex I386_USE_GENERIC_WATCHPOINTS | |
536 | @item | |
537 | Define the macro @code{I386_USE_GENERIC_WATCHPOINTS} somewhere in the | |
538 | target-dependent headers. | |
539 | ||
540 | @item | |
541 | Include the @file{config/i386/nm-i386.h} header file @emph{after} | |
542 | defining @code{I386_USE_GENERIC_WATCHPOINTS}. | |
543 | ||
544 | @item | |
545 | Add @file{i386-nat.o} to the value of the Make variable | |
546 | @code{NATDEPFILES} (@pxref{Native Debugging, NATDEPFILES}) or | |
547 | @code{TDEPFILES} (@pxref{Target Architecture Definition, TDEPFILES}). | |
548 | ||
549 | @item | |
550 | Provide implementations for the @code{I386_DR_LOW_*} macros described | |
551 | below. Typically, each macro should call a target-specific function | |
552 | which does the real work. | |
553 | @end itemize | |
554 | ||
555 | The x86 watchpoint support works by maintaining mirror images of the | |
556 | debug registers. Values are copied between the mirror images and the | |
557 | real debug registers via a set of macros which each target needs to | |
558 | provide: | |
559 | ||
560 | @table @code | |
561 | @findex I386_DR_LOW_SET_CONTROL | |
562 | @item I386_DR_LOW_SET_CONTROL (@var{val}) | |
563 | Set the Debug Control (DR7) register to the value @var{val}. | |
564 | ||
565 | @findex I386_DR_LOW_SET_ADDR | |
566 | @item I386_DR_LOW_SET_ADDR (@var{idx}, @var{addr}) | |
567 | Put the address @var{addr} into the debug register number @var{idx}. | |
568 | ||
569 | @findex I386_DR_LOW_RESET_ADDR | |
570 | @item I386_DR_LOW_RESET_ADDR (@var{idx}) | |
571 | Reset (i.e.@: zero out) the address stored in the debug register | |
572 | number @var{idx}. | |
573 | ||
574 | @findex I386_DR_LOW_GET_STATUS | |
575 | @item I386_DR_LOW_GET_STATUS | |
576 | Return the value of the Debug Status (DR6) register. This value is | |
577 | used immediately after it is returned by | |
578 | @code{I386_DR_LOW_GET_STATUS}, so as to support per-thread status | |
579 | register values. | |
580 | @end table | |
581 | ||
582 | For each one of the 4 debug registers (whose indices are from 0 to 3) | |
583 | that store addresses, a reference count is maintained by @value{GDBN}, | |
584 | to allow sharing of debug registers by several watchpoints. This | |
585 | allows users to define several watchpoints that watch the same | |
586 | expression, but with different conditions and/or commands, without | |
587 | wasting debug registers which are in short supply. @value{GDBN} | |
588 | maintains the reference counts internally, targets don't have to do | |
589 | anything to use this feature. | |
590 | ||
591 | The x86 debug registers can each watch a region that is 1, 2, or 4 | |
592 | bytes long. The ia32 architecture requires that each watched region | |
593 | be appropriately aligned: 2-byte region on 2-byte boundary, 4-byte | |
594 | region on 4-byte boundary. However, the x86 watchpoint support in | |
595 | @value{GDBN} can watch unaligned regions and regions larger than 4 | |
596 | bytes (up to 16 bytes) by allocating several debug registers to watch | |
597 | a single region. This allocation of several registers per a watched | |
598 | region is also done automatically without target code intervention. | |
599 | ||
600 | The generic x86 watchpoint support provides the following API for the | |
601 | @value{GDBN}'s application code: | |
602 | ||
603 | @table @code | |
604 | @findex i386_region_ok_for_watchpoint | |
605 | @item i386_region_ok_for_watchpoint (@var{addr}, @var{len}) | |
606 | The macro @code{TARGET_REGION_OK_FOR_HW_WATCHPOINT} is set to call | |
607 | this function. It counts the number of debug registers required to | |
608 | watch a given region, and returns a non-zero value if that number is | |
609 | less than 4, the number of debug registers available to x86 | |
610 | processors. | |
611 | ||
612 | @findex i386_stopped_data_address | |
613 | @item i386_stopped_data_address (void) | |
614 | The macros @code{STOPPED_BY_WATCHPOINT} and | |
615 | @code{target_stopped_data_address} are set to call this function. The | |
616 | argument passed to @code{STOPPED_BY_WATCHPOINT} is ignored. This | |
617 | function examines the breakpoint condition bits in the DR6 Debug | |
618 | Status register, as returned by the @code{I386_DR_LOW_GET_STATUS} | |
619 | macro, and returns the address associated with the first bit that is | |
620 | set in DR6. | |
621 | ||
622 | @findex i386_insert_watchpoint | |
623 | @findex i386_remove_watchpoint | |
624 | @item i386_insert_watchpoint (@var{addr}, @var{len}, @var{type}) | |
625 | @itemx i386_remove_watchpoint (@var{addr}, @var{len}, @var{type}) | |
626 | Insert or remove a watchpoint. The macros | |
627 | @code{target_insert_watchpoint} and @code{target_remove_watchpoint} | |
628 | are set to call these functions. @code{i386_insert_watchpoint} first | |
629 | looks for a debug register which is already set to watch the same | |
630 | region for the same access types; if found, it just increments the | |
631 | reference count of that debug register, thus implementing debug | |
632 | register sharing between watchpoints. If no such register is found, | |
633 | the function looks for a vacant debug register, sets its mirrorred | |
634 | value to @var{addr}, sets the mirrorred value of DR7 Debug Control | |
635 | register as appropriate for the @var{len} and @var{type} parameters, | |
636 | and then passes the new values of the debug register and DR7 to the | |
637 | inferior by calling @code{I386_DR_LOW_SET_ADDR} and | |
638 | @code{I386_DR_LOW_SET_CONTROL}. If more than one debug register is | |
639 | required to cover the given region, the above process is repeated for | |
640 | each debug register. | |
641 | ||
642 | @code{i386_remove_watchpoint} does the opposite: it resets the address | |
643 | in the mirrorred value of the debug register and its read/write and | |
644 | length bits in the mirrorred value of DR7, then passes these new | |
645 | values to the inferior via @code{I386_DR_LOW_RESET_ADDR} and | |
646 | @code{I386_DR_LOW_SET_CONTROL}. If a register is shared by several | |
647 | watchpoints, each time a @code{i386_remove_watchpoint} is called, it | |
648 | decrements the reference count, and only calls | |
649 | @code{I386_DR_LOW_RESET_ADDR} and @code{I386_DR_LOW_SET_CONTROL} when | |
650 | the count goes to zero. | |
651 | ||
652 | @findex i386_insert_hw_breakpoint | |
653 | @findex i386_remove_hw_breakpoint | |
654 | @item i386_insert_hw_breakpoint (@var{addr}, @var{shadow} | |
655 | @itemx i386_remove_hw_breakpoint (@var{addr}, @var{shadow}) | |
656 | These functions insert and remove hardware-assisted breakpoints. The | |
657 | macros @code{target_insert_hw_breakpoint} and | |
658 | @code{target_remove_hw_breakpoint} are set to call these functions. | |
659 | These functions work like @code{i386_insert_watchpoint} and | |
660 | @code{i386_remove_watchpoint}, respectively, except that they set up | |
661 | the debug registers to watch instruction execution, and each | |
662 | hardware-assisted breakpoint always requires exactly one debug | |
663 | register. | |
664 | ||
665 | @findex i386_stopped_by_hwbp | |
666 | @item i386_stopped_by_hwbp (void) | |
667 | This function returns non-zero if the inferior has some watchpoint or | |
668 | hardware breakpoint that triggered. It works like | |
669 | @code{i386_stopped_data_address}, except that it doesn't return the | |
670 | address whose watchpoint triggered. | |
671 | ||
672 | @findex i386_cleanup_dregs | |
673 | @item i386_cleanup_dregs (void) | |
674 | This function clears all the reference counts, addresses, and control | |
675 | bits in the mirror images of the debug registers. It doesn't affect | |
676 | the actual debug registers in the inferior process. | |
677 | @end table | |
678 | ||
679 | @noindent | |
680 | @strong{Notes:} | |
681 | @enumerate 1 | |
682 | @item | |
683 | x86 processors support setting watchpoints on I/O reads or writes. | |
684 | However, since no target supports this (as of March 2001), and since | |
685 | @code{enum target_hw_bp_type} doesn't even have an enumeration for I/O | |
686 | watchpoints, this feature is not yet available to @value{GDBN} running | |
687 | on x86. | |
688 | ||
689 | @item | |
690 | x86 processors can enable watchpoints locally, for the current task | |
691 | only, or globally, for all the tasks. For each debug register, | |
692 | there's a bit in the DR7 Debug Control register that determines | |
693 | whether the associated address is watched locally or globally. The | |
694 | current implementation of x86 watchpoint support in @value{GDBN} | |
695 | always sets watchpoints to be locally enabled, since global | |
696 | watchpoints might interfere with the underlying OS and are probably | |
697 | unavailable in many platforms. | |
698 | @end enumerate | |
699 | ||
c906108c SS |
700 | @node User Interface |
701 | ||
702 | @chapter User Interface | |
703 | ||
25822942 | 704 | @value{GDBN} has several user interfaces. Although the command-line interface |
c906108c SS |
705 | is the most common and most familiar, there are others. |
706 | ||
707 | @section Command Interpreter | |
708 | ||
56caf160 | 709 | @cindex command interpreter |
0ee54786 | 710 | @cindex CLI |
25822942 | 711 | The command interpreter in @value{GDBN} is fairly simple. It is designed to |
c906108c SS |
712 | allow for the set of commands to be augmented dynamically, and also |
713 | has a recursive subcommand capability, where the first argument to | |
714 | a command may itself direct a lookup on a different command list. | |
715 | ||
56caf160 EZ |
716 | For instance, the @samp{set} command just starts a lookup on the |
717 | @code{setlist} command list, while @samp{set thread} recurses | |
c906108c SS |
718 | to the @code{set_thread_cmd_list}. |
719 | ||
56caf160 EZ |
720 | @findex add_cmd |
721 | @findex add_com | |
c906108c SS |
722 | To add commands in general, use @code{add_cmd}. @code{add_com} adds to |
723 | the main command list, and should be used for those commands. The usual | |
cfeada60 | 724 | place to add commands is in the @code{_initialize_@var{xyz}} routines at |
9742079a | 725 | the ends of most source files. |
cfeada60 | 726 | |
56caf160 EZ |
727 | @cindex deprecating commands |
728 | @findex deprecate_cmd | |
cfeada60 FN |
729 | Before removing commands from the command set it is a good idea to |
730 | deprecate them for some time. Use @code{deprecate_cmd} on commands or | |
731 | aliases to set the deprecated flag. @code{deprecate_cmd} takes a | |
732 | @code{struct cmd_list_element} as it's first argument. You can use the | |
733 | return value from @code{add_com} or @code{add_cmd} to deprecate the | |
734 | command immediately after it is created. | |
735 | ||
c72e7388 | 736 | The first time a command is used the user will be warned and offered a |
cfeada60 FN |
737 | replacement (if one exists). Note that the replacement string passed to |
738 | @code{deprecate_cmd} should be the full name of the command, i.e. the | |
739 | entire string the user should type at the command line. | |
c906108c | 740 | |
0ee54786 EZ |
741 | @section UI-Independent Output---the @code{ui_out} Functions |
742 | @c This section is based on the documentation written by Fernando | |
743 | @c Nasser <fnasser@redhat.com>. | |
744 | ||
745 | @cindex @code{ui_out} functions | |
746 | The @code{ui_out} functions present an abstraction level for the | |
747 | @value{GDBN} output code. They hide the specifics of different user | |
748 | interfaces supported by @value{GDBN}, and thus free the programmer | |
749 | from the need to write several versions of the same code, one each for | |
750 | every UI, to produce output. | |
751 | ||
752 | @subsection Overview and Terminology | |
753 | ||
754 | In general, execution of each @value{GDBN} command produces some sort | |
755 | of output, and can even generate an input request. | |
756 | ||
757 | Output can be generated for the following purposes: | |
758 | ||
759 | @itemize @bullet | |
760 | @item | |
761 | to display a @emph{result} of an operation; | |
762 | ||
763 | @item | |
764 | to convey @emph{info} or produce side-effects of a requested | |
765 | operation; | |
766 | ||
767 | @item | |
768 | to provide a @emph{notification} of an asynchronous event (including | |
769 | progress indication of a prolonged asynchronous operation); | |
770 | ||
771 | @item | |
772 | to display @emph{error messages} (including warnings); | |
773 | ||
774 | @item | |
775 | to show @emph{debug data}; | |
776 | ||
777 | @item | |
778 | to @emph{query} or prompt a user for input (a special case). | |
779 | @end itemize | |
780 | ||
781 | @noindent | |
782 | This section mainly concentrates on how to build result output, | |
783 | although some of it also applies to other kinds of output. | |
784 | ||
785 | Generation of output that displays the results of an operation | |
786 | involves one or more of the following: | |
787 | ||
788 | @itemize @bullet | |
789 | @item | |
790 | output of the actual data | |
791 | ||
792 | @item | |
793 | formatting the output as appropriate for console output, to make it | |
794 | easily readable by humans | |
795 | ||
796 | @item | |
797 | machine oriented formatting--a more terse formatting to allow for easy | |
798 | parsing by programs which read @value{GDBN}'s output | |
799 | ||
800 | @item | |
c72e7388 AC |
801 | annotation, whose purpose is to help legacy GUIs to identify interesting |
802 | parts in the output | |
0ee54786 EZ |
803 | @end itemize |
804 | ||
805 | The @code{ui_out} routines take care of the first three aspects. | |
c72e7388 AC |
806 | Annotations are provided by separate annotation routines. Note that use |
807 | of annotations for an interface between a GUI and @value{GDBN} is | |
0ee54786 EZ |
808 | deprecated. |
809 | ||
c72e7388 AC |
810 | Output can be in the form of a single item, which we call a @dfn{field}; |
811 | a @dfn{list} consisting of identical fields; a @dfn{tuple} consisting of | |
812 | non-identical fields; or a @dfn{table}, which is a tuple consisting of a | |
813 | header and a body. In a BNF-like form: | |
0ee54786 | 814 | |
c72e7388 AC |
815 | @table @code |
816 | @item <table> @expansion{} | |
817 | @code{<header> <body>} | |
818 | @item <header> @expansion{} | |
819 | @code{@{ <column> @}} | |
820 | @item <column> @expansion{} | |
821 | @code{<width> <alignment> <title>} | |
822 | @item <body> @expansion{} | |
823 | @code{@{<row>@}} | |
824 | @end table | |
0ee54786 EZ |
825 | |
826 | ||
827 | @subsection General Conventions | |
828 | ||
c72e7388 AC |
829 | Most @code{ui_out} routines are of type @code{void}, the exceptions are |
830 | @code{ui_out_stream_new} (which returns a pointer to the newly created | |
831 | object) and the @code{make_cleanup} routines. | |
0ee54786 | 832 | |
c72e7388 AC |
833 | The first parameter is always the @code{ui_out} vector object, a pointer |
834 | to a @code{struct ui_out}. | |
0ee54786 | 835 | |
c72e7388 AC |
836 | The @var{format} parameter is like in @code{printf} family of functions. |
837 | When it is present, there must also be a variable list of arguments | |
838 | sufficient used to satisfy the @code{%} specifiers in the supplied | |
0ee54786 EZ |
839 | format. |
840 | ||
c72e7388 AC |
841 | When a character string argument is not used in a @code{ui_out} function |
842 | call, a @code{NULL} pointer has to be supplied instead. | |
0ee54786 EZ |
843 | |
844 | ||
c72e7388 | 845 | @subsection Table, Tuple and List Functions |
0ee54786 EZ |
846 | |
847 | @cindex list output functions | |
848 | @cindex table output functions | |
c72e7388 AC |
849 | @cindex tuple output functions |
850 | This section introduces @code{ui_out} routines for building lists, | |
851 | tuples and tables. The routines to output the actual data items | |
852 | (fields) are presented in the next section. | |
0ee54786 | 853 | |
c72e7388 AC |
854 | To recap: A @dfn{tuple} is a sequence of @dfn{fields}, each field |
855 | containing information about an object; a @dfn{list} is a sequence of | |
856 | fields where each field describes an identical object. | |
0ee54786 | 857 | |
c72e7388 AC |
858 | Use the @dfn{table} functions when your output consists of a list of |
859 | rows (tuples) and the console output should include a heading. Use this | |
860 | even when you are listing just one object but you still want the header. | |
0ee54786 EZ |
861 | |
862 | @cindex nesting level in @code{ui_out} functions | |
c72e7388 AC |
863 | Tables can not be nested. Tuples and lists can be nested up to a |
864 | maximum of five levels. | |
0ee54786 EZ |
865 | |
866 | The overall structure of the table output code is something like this: | |
867 | ||
868 | @example | |
869 | ui_out_table_begin | |
870 | ui_out_table_header | |
c72e7388 | 871 | @dots{} |
0ee54786 | 872 | ui_out_table_body |
c72e7388 | 873 | ui_out_tuple_begin |
0ee54786 | 874 | ui_out_field_* |
c72e7388 AC |
875 | @dots{} |
876 | ui_out_tuple_end | |
877 | @dots{} | |
0ee54786 EZ |
878 | ui_out_table_end |
879 | @end example | |
880 | ||
c72e7388 | 881 | Here is the description of table-, tuple- and list-related @code{ui_out} |
0ee54786 EZ |
882 | functions: |
883 | ||
c72e7388 AC |
884 | @deftypefun void ui_out_table_begin (struct ui_out *@var{uiout}, int @var{nbrofcols}, int @var{nr_rows}, const char *@var{tblid}) |
885 | The function @code{ui_out_table_begin} marks the beginning of the output | |
886 | of a table. It should always be called before any other @code{ui_out} | |
887 | function for a given table. @var{nbrofcols} is the number of columns in | |
888 | the table. @var{nr_rows} is the number of rows in the table. | |
889 | @var{tblid} is an optional string identifying the table. The string | |
890 | pointed to by @var{tblid} is copied by the implementation of | |
891 | @code{ui_out_table_begin}, so the application can free the string if it | |
892 | was @code{malloc}ed. | |
0ee54786 EZ |
893 | |
894 | The companion function @code{ui_out_table_end}, described below, marks | |
895 | the end of the table's output. | |
896 | @end deftypefun | |
897 | ||
c72e7388 AC |
898 | @deftypefun void ui_out_table_header (struct ui_out *@var{uiout}, int @var{width}, enum ui_align @var{alignment}, const char *@var{colhdr}) |
899 | @code{ui_out_table_header} provides the header information for a single | |
900 | table column. You call this function several times, one each for every | |
901 | column of the table, after @code{ui_out_table_begin}, but before | |
902 | @code{ui_out_table_body}. | |
0ee54786 EZ |
903 | |
904 | The value of @var{width} gives the column width in characters. The | |
905 | value of @var{alignment} is one of @code{left}, @code{center}, and | |
906 | @code{right}, and it specifies how to align the header: left-justify, | |
907 | center, or right-justify it. @var{colhdr} points to a string that | |
908 | specifies the column header; the implementation copies that string, so | |
c72e7388 AC |
909 | column header strings in @code{malloc}ed storage can be freed after the |
910 | call. | |
0ee54786 EZ |
911 | @end deftypefun |
912 | ||
913 | @deftypefun void ui_out_table_body (struct ui_out *@var{uiout}) | |
c72e7388 | 914 | This function delimits the table header from the table body. |
0ee54786 EZ |
915 | @end deftypefun |
916 | ||
917 | @deftypefun void ui_out_table_end (struct ui_out *@var{uiout}) | |
c72e7388 AC |
918 | This function signals the end of a table's output. It should be called |
919 | after the table body has been produced by the list and field output | |
920 | functions. | |
0ee54786 EZ |
921 | |
922 | There should be exactly one call to @code{ui_out_table_end} for each | |
c72e7388 AC |
923 | call to @code{ui_out_table_begin}, otherwise the @code{ui_out} functions |
924 | will signal an internal error. | |
0ee54786 EZ |
925 | @end deftypefun |
926 | ||
c72e7388 | 927 | The output of the tuples that represent the table rows must follow the |
0ee54786 | 928 | call to @code{ui_out_table_body} and precede the call to |
c72e7388 AC |
929 | @code{ui_out_table_end}. You build a tuple by calling |
930 | @code{ui_out_tuple_begin} and @code{ui_out_tuple_end}, with suitable | |
0ee54786 EZ |
931 | calls to functions which actually output fields between them. |
932 | ||
c72e7388 AC |
933 | @deftypefun void ui_out_tuple_begin (struct ui_out *@var{uiout}, const char *@var{id}) |
934 | This function marks the beginning of a tuple output. @var{id} points | |
935 | to an optional string that identifies the tuple; it is copied by the | |
936 | implementation, and so strings in @code{malloc}ed storage can be freed | |
937 | after the call. | |
938 | @end deftypefun | |
939 | ||
940 | @deftypefun void ui_out_tuple_end (struct ui_out *@var{uiout}) | |
941 | This function signals an end of a tuple output. There should be exactly | |
942 | one call to @code{ui_out_tuple_end} for each call to | |
943 | @code{ui_out_tuple_begin}, otherwise an internal @value{GDBN} error will | |
944 | be signaled. | |
945 | @end deftypefun | |
946 | ||
947 | @deftypefun struct cleanup *make_cleanup_ui_out_tuple_begin_end (struct ui_out *@var{uiout}, const char *@var{id}) | |
948 | This function first opens the tuple and then establishes a cleanup | |
949 | (@pxref{Coding, Cleanups}) to close the tuple. It provides a convenient | |
950 | and correct implementation of the non-portable@footnote{The function | |
951 | cast is not portable ISO-C.} code sequence: | |
952 | @smallexample | |
953 | struct cleanup *old_cleanup; | |
954 | ui_out_tuple_begin (uiout, "..."); | |
955 | old_cleanup = make_cleanup ((void(*)(void *)) ui_out_tuple_end, | |
956 | uiout); | |
957 | @end smallexample | |
958 | @end deftypefun | |
959 | ||
960 | @deftypefun void ui_out_list_begin (struct ui_out *@var{uiout}, const char *@var{id}) | |
961 | This function marks the beginning of a list output. @var{id} points to | |
962 | an optional string that identifies the list; it is copied by the | |
963 | implementation, and so strings in @code{malloc}ed storage can be freed | |
964 | after the call. | |
0ee54786 EZ |
965 | @end deftypefun |
966 | ||
967 | @deftypefun void ui_out_list_end (struct ui_out *@var{uiout}) | |
c72e7388 AC |
968 | This function signals an end of a list output. There should be exactly |
969 | one call to @code{ui_out_list_end} for each call to | |
970 | @code{ui_out_list_begin}, otherwise an internal @value{GDBN} error will | |
971 | be signaled. | |
972 | @end deftypefun | |
973 | ||
974 | @deftypefun struct cleanup *make_cleanup_ui_out_list_begin_end (struct ui_out *@var{uiout}, const char *@var{id}) | |
975 | Similar to @code{make_cleanup_ui_out_tuple_begin_end}, this function | |
976 | opens a list and then establishes cleanup (@pxref{Coding, Cleanups}) | |
977 | that will close the list.list. | |
0ee54786 EZ |
978 | @end deftypefun |
979 | ||
980 | @subsection Item Output Functions | |
981 | ||
982 | @cindex item output functions | |
983 | @cindex field output functions | |
984 | @cindex data output | |
985 | The functions described below produce output for the actual data | |
986 | items, or fields, which contain information about the object. | |
987 | ||
988 | Choose the appropriate function accordingly to your particular needs. | |
989 | ||
990 | @deftypefun void ui_out_field_fmt (struct ui_out *@var{uiout}, char *@var{fldname}, char *@var{format}, ...) | |
991 | This is the most general output function. It produces the | |
992 | representation of the data in the variable-length argument list | |
993 | according to formatting specifications in @var{format}, a | |
994 | @code{printf}-like format string. The optional argument @var{fldname} | |
995 | supplies the name of the field. The data items themselves are | |
996 | supplied as additional arguments after @var{format}. | |
997 | ||
998 | This generic function should be used only when it is not possible to | |
999 | use one of the specialized versions (see below). | |
1000 | @end deftypefun | |
1001 | ||
c72e7388 | 1002 | @deftypefun void ui_out_field_int (struct ui_out *@var{uiout}, const char *@var{fldname}, int @var{value}) |
0ee54786 EZ |
1003 | This function outputs a value of an @code{int} variable. It uses the |
1004 | @code{"%d"} output conversion specification. @var{fldname} specifies | |
1005 | the name of the field. | |
1006 | @end deftypefun | |
1007 | ||
c72e7388 | 1008 | @deftypefun void ui_out_field_core_addr (struct ui_out *@var{uiout}, const char *@var{fldname}, CORE_ADDR @var{address}) |
0ee54786 EZ |
1009 | This function outputs an address. |
1010 | @end deftypefun | |
1011 | ||
c72e7388 | 1012 | @deftypefun void ui_out_field_string (struct ui_out *@var{uiout}, const char *@var{fldname}, const char *@var{string}) |
0ee54786 EZ |
1013 | This function outputs a string using the @code{"%s"} conversion |
1014 | specification. | |
1015 | @end deftypefun | |
1016 | ||
1017 | Sometimes, there's a need to compose your output piece by piece using | |
1018 | functions that operate on a stream, such as @code{value_print} or | |
1019 | @code{fprintf_symbol_filtered}. These functions accept an argument of | |
1020 | the type @code{struct ui_file *}, a pointer to a @code{ui_file} object | |
1021 | used to store the data stream used for the output. When you use one | |
1022 | of these functions, you need a way to pass their results stored in a | |
1023 | @code{ui_file} object to the @code{ui_out} functions. To this end, | |
1024 | you first create a @code{ui_stream} object by calling | |
1025 | @code{ui_out_stream_new}, pass the @code{stream} member of that | |
1026 | @code{ui_stream} object to @code{value_print} and similar functions, | |
1027 | and finally call @code{ui_out_field_stream} to output the field you | |
1028 | constructed. When the @code{ui_stream} object is no longer needed, | |
1029 | you should destroy it and free its memory by calling | |
1030 | @code{ui_out_stream_delete}. | |
1031 | ||
1032 | @deftypefun struct ui_stream *ui_out_stream_new (struct ui_out *@var{uiout}) | |
1033 | This function creates a new @code{ui_stream} object which uses the | |
1034 | same output methods as the @code{ui_out} object whose pointer is | |
1035 | passed in @var{uiout}. It returns a pointer to the newly created | |
1036 | @code{ui_stream} object. | |
1037 | @end deftypefun | |
1038 | ||
1039 | @deftypefun void ui_out_stream_delete (struct ui_stream *@var{streambuf}) | |
1040 | This functions destroys a @code{ui_stream} object specified by | |
1041 | @var{streambuf}. | |
1042 | @end deftypefun | |
1043 | ||
c72e7388 | 1044 | @deftypefun void ui_out_field_stream (struct ui_out *@var{uiout}, const char *@var{fieldname}, struct ui_stream *@var{streambuf}) |
0ee54786 EZ |
1045 | This function consumes all the data accumulated in |
1046 | @code{streambuf->stream} and outputs it like | |
1047 | @code{ui_out_field_string} does. After a call to | |
1048 | @code{ui_out_field_stream}, the accumulated data no longer exists, but | |
1049 | the stream is still valid and may be used for producing more fields. | |
1050 | @end deftypefun | |
1051 | ||
1052 | @strong{Important:} If there is any chance that your code could bail | |
1053 | out before completing output generation and reaching the point where | |
1054 | @code{ui_out_stream_delete} is called, it is necessary to set up a | |
1055 | cleanup, to avoid leaking memory and other resources. Here's a | |
1056 | skeleton code to do that: | |
1057 | ||
1058 | @smallexample | |
1059 | struct ui_stream *mybuf = ui_out_stream_new (uiout); | |
1060 | struct cleanup *old = make_cleanup (ui_out_stream_delete, mybuf); | |
1061 | ... | |
1062 | do_cleanups (old); | |
1063 | @end smallexample | |
1064 | ||
1065 | If the function already has the old cleanup chain set (for other kinds | |
1066 | of cleanups), you just have to add your cleanup to it: | |
1067 | ||
1068 | @smallexample | |
1069 | mybuf = ui_out_stream_new (uiout); | |
1070 | make_cleanup (ui_out_stream_delete, mybuf); | |
1071 | @end smallexample | |
1072 | ||
1073 | Note that with cleanups in place, you should not call | |
1074 | @code{ui_out_stream_delete} directly, or you would attempt to free the | |
1075 | same buffer twice. | |
1076 | ||
1077 | @subsection Utility Output Functions | |
1078 | ||
c72e7388 | 1079 | @deftypefun void ui_out_field_skip (struct ui_out *@var{uiout}, const char *@var{fldname}) |
0ee54786 EZ |
1080 | This function skips a field in a table. Use it if you have to leave |
1081 | an empty field without disrupting the table alignment. The argument | |
1082 | @var{fldname} specifies a name for the (missing) filed. | |
1083 | @end deftypefun | |
1084 | ||
c72e7388 | 1085 | @deftypefun void ui_out_text (struct ui_out *@var{uiout}, const char *@var{string}) |
0ee54786 EZ |
1086 | This function outputs the text in @var{string} in a way that makes it |
1087 | easy to be read by humans. For example, the console implementation of | |
1088 | this method filters the text through a built-in pager, to prevent it | |
1089 | from scrolling off the visible portion of the screen. | |
1090 | ||
1091 | Use this function for printing relatively long chunks of text around | |
1092 | the actual field data: the text it produces is not aligned according | |
1093 | to the table's format. Use @code{ui_out_field_string} to output a | |
1094 | string field, and use @code{ui_out_message}, described below, to | |
1095 | output short messages. | |
1096 | @end deftypefun | |
1097 | ||
1098 | @deftypefun void ui_out_spaces (struct ui_out *@var{uiout}, int @var{nspaces}) | |
1099 | This function outputs @var{nspaces} spaces. It is handy to align the | |
1100 | text produced by @code{ui_out_text} with the rest of the table or | |
1101 | list. | |
1102 | @end deftypefun | |
1103 | ||
c72e7388 | 1104 | @deftypefun void ui_out_message (struct ui_out *@var{uiout}, int @var{verbosity}, const char *@var{format}, ...) |
0ee54786 EZ |
1105 | This function produces a formatted message, provided that the current |
1106 | verbosity level is at least as large as given by @var{verbosity}. The | |
1107 | current verbosity level is specified by the user with the @samp{set | |
1108 | verbositylevel} command.@footnote{As of this writing (April 2001), | |
1109 | setting verbosity level is not yet implemented, and is always returned | |
1110 | as zero. So calling @code{ui_out_message} with a @var{verbosity} | |
1111 | argument more than zero will cause the message to never be printed.} | |
1112 | @end deftypefun | |
1113 | ||
1114 | @deftypefun void ui_out_wrap_hint (struct ui_out *@var{uiout}, char *@var{indent}) | |
1115 | This function gives the console output filter (a paging filter) a hint | |
1116 | of where to break lines which are too long. Ignored for all other | |
1117 | output consumers. @var{indent}, if non-@code{NULL}, is the string to | |
1118 | be printed to indent the wrapped text on the next line; it must remain | |
1119 | accessible until the next call to @code{ui_out_wrap_hint}, or until an | |
1120 | explicit newline is produced by one of the other functions. If | |
1121 | @var{indent} is @code{NULL}, the wrapped text will not be indented. | |
1122 | @end deftypefun | |
1123 | ||
1124 | @deftypefun void ui_out_flush (struct ui_out *@var{uiout}) | |
1125 | This function flushes whatever output has been accumulated so far, if | |
1126 | the UI buffers output. | |
1127 | @end deftypefun | |
1128 | ||
1129 | ||
1130 | @subsection Examples of Use of @code{ui_out} functions | |
1131 | ||
1132 | @cindex using @code{ui_out} functions | |
1133 | @cindex @code{ui_out} functions, usage examples | |
1134 | This section gives some practical examples of using the @code{ui_out} | |
1135 | functions to generalize the old console-oriented code in | |
1136 | @value{GDBN}. The examples all come from functions defined on the | |
1137 | @file{breakpoints.c} file. | |
1138 | ||
1139 | This example, from the @code{breakpoint_1} function, shows how to | |
1140 | produce a table. | |
1141 | ||
1142 | The original code was: | |
1143 | ||
1144 | @example | |
1145 | if (!found_a_breakpoint++) | |
1146 | @{ | |
1147 | annotate_breakpoints_headers (); | |
1148 | ||
1149 | annotate_field (0); | |
1150 | printf_filtered ("Num "); | |
1151 | annotate_field (1); | |
1152 | printf_filtered ("Type "); | |
1153 | annotate_field (2); | |
1154 | printf_filtered ("Disp "); | |
1155 | annotate_field (3); | |
1156 | printf_filtered ("Enb "); | |
1157 | if (addressprint) | |
1158 | @{ | |
1159 | annotate_field (4); | |
1160 | printf_filtered ("Address "); | |
1161 | @} | |
1162 | annotate_field (5); | |
1163 | printf_filtered ("What\n"); | |
1164 | ||
1165 | annotate_breakpoints_table (); | |
1166 | @} | |
1167 | @end example | |
1168 | ||
1169 | Here's the new version: | |
1170 | ||
1171 | @example | |
c72e7388 AC |
1172 | nr_printable_breakpoints = @dots{}; |
1173 | ||
1174 | if (addressprint) | |
1175 | ui_out_table_begin (ui, 6, nr_printable_breakpoints, "BreakpointTable"); | |
1176 | else | |
1177 | ui_out_table_begin (ui, 5, nr_printable_breakpoints, "BreakpointTable"); | |
1178 | ||
1179 | if (nr_printable_breakpoints > 0) | |
1180 | annotate_breakpoints_headers (); | |
1181 | if (nr_printable_breakpoints > 0) | |
1182 | annotate_field (0); | |
1183 | ui_out_table_header (uiout, 3, ui_left, "number", "Num"); /* 1 */ | |
1184 | if (nr_printable_breakpoints > 0) | |
1185 | annotate_field (1); | |
1186 | ui_out_table_header (uiout, 14, ui_left, "type", "Type"); /* 2 */ | |
1187 | if (nr_printable_breakpoints > 0) | |
1188 | annotate_field (2); | |
1189 | ui_out_table_header (uiout, 4, ui_left, "disp", "Disp"); /* 3 */ | |
1190 | if (nr_printable_breakpoints > 0) | |
1191 | annotate_field (3); | |
1192 | ui_out_table_header (uiout, 3, ui_left, "enabled", "Enb"); /* 4 */ | |
1193 | if (addressprint) | |
1194 | @{ | |
1195 | if (nr_printable_breakpoints > 0) | |
1196 | annotate_field (4); | |
1197 | if (TARGET_ADDR_BIT <= 32) | |
1198 | ui_out_table_header (uiout, 10, ui_left, "addr", "Address");/* 5 */ | |
0ee54786 | 1199 | else |
c72e7388 AC |
1200 | ui_out_table_header (uiout, 18, ui_left, "addr", "Address");/* 5 */ |
1201 | @} | |
1202 | if (nr_printable_breakpoints > 0) | |
1203 | annotate_field (5); | |
1204 | ui_out_table_header (uiout, 40, ui_noalign, "what", "What"); /* 6 */ | |
1205 | ui_out_table_body (uiout); | |
1206 | if (nr_printable_breakpoints > 0) | |
1207 | annotate_breakpoints_table (); | |
0ee54786 EZ |
1208 | @end example |
1209 | ||
1210 | This example, from the @code{print_one_breakpoint} function, shows how | |
1211 | to produce the actual data for the table whose structure was defined | |
1212 | in the above example. The original code was: | |
1213 | ||
1214 | @example | |
1215 | annotate_record (); | |
1216 | annotate_field (0); | |
1217 | printf_filtered ("%-3d ", b->number); | |
1218 | annotate_field (1); | |
1219 | if ((int)b->type > (sizeof(bptypes)/sizeof(bptypes[0])) | |
1220 | || ((int) b->type != bptypes[(int) b->type].type)) | |
1221 | internal_error ("bptypes table does not describe type #%d.", | |
1222 | (int)b->type); | |
1223 | printf_filtered ("%-14s ", bptypes[(int)b->type].description); | |
1224 | annotate_field (2); | |
1225 | printf_filtered ("%-4s ", bpdisps[(int)b->disposition]); | |
1226 | annotate_field (3); | |
1227 | printf_filtered ("%-3c ", bpenables[(int)b->enable]); | |
c72e7388 | 1228 | @dots{} |
0ee54786 EZ |
1229 | @end example |
1230 | ||
1231 | This is the new version: | |
1232 | ||
1233 | @example | |
1234 | annotate_record (); | |
c72e7388 | 1235 | ui_out_tuple_begin (uiout, "bkpt"); |
0ee54786 EZ |
1236 | annotate_field (0); |
1237 | ui_out_field_int (uiout, "number", b->number); | |
1238 | annotate_field (1); | |
1239 | if (((int) b->type > (sizeof (bptypes) / sizeof (bptypes[0]))) | |
1240 | || ((int) b->type != bptypes[(int) b->type].type)) | |
1241 | internal_error ("bptypes table does not describe type #%d.", | |
1242 | (int) b->type); | |
1243 | ui_out_field_string (uiout, "type", bptypes[(int)b->type].description); | |
1244 | annotate_field (2); | |
1245 | ui_out_field_string (uiout, "disp", bpdisps[(int)b->disposition]); | |
1246 | annotate_field (3); | |
1247 | ui_out_field_fmt (uiout, "enabled", "%c", bpenables[(int)b->enable]); | |
c72e7388 | 1248 | @dots{} |
0ee54786 EZ |
1249 | @end example |
1250 | ||
1251 | This example, also from @code{print_one_breakpoint}, shows how to | |
1252 | produce a complicated output field using the @code{print_expression} | |
1253 | functions which requires a stream to be passed. It also shows how to | |
1254 | automate stream destruction with cleanups. The original code was: | |
1255 | ||
1256 | @example | |
1257 | annotate_field (5); | |
1258 | print_expression (b->exp, gdb_stdout); | |
1259 | @end example | |
1260 | ||
1261 | The new version is: | |
1262 | ||
1263 | @example | |
1264 | struct ui_stream *stb = ui_out_stream_new (uiout); | |
1265 | struct cleanup *old_chain = make_cleanup_ui_out_stream_delete (stb); | |
1266 | ... | |
1267 | annotate_field (5); | |
1268 | print_expression (b->exp, stb->stream); | |
1269 | ui_out_field_stream (uiout, "what", local_stream); | |
1270 | @end example | |
1271 | ||
1272 | This example, also from @code{print_one_breakpoint}, shows how to use | |
1273 | @code{ui_out_text} and @code{ui_out_field_string}. The original code | |
1274 | was: | |
1275 | ||
1276 | @example | |
1277 | annotate_field (5); | |
1278 | if (b->dll_pathname == NULL) | |
1279 | printf_filtered ("<any library> "); | |
1280 | else | |
1281 | printf_filtered ("library \"%s\" ", b->dll_pathname); | |
1282 | @end example | |
1283 | ||
1284 | It became: | |
1285 | ||
1286 | @example | |
1287 | annotate_field (5); | |
1288 | if (b->dll_pathname == NULL) | |
1289 | @{ | |
1290 | ui_out_field_string (uiout, "what", "<any library>"); | |
1291 | ui_out_spaces (uiout, 1); | |
1292 | @} | |
1293 | else | |
1294 | @{ | |
1295 | ui_out_text (uiout, "library \""); | |
1296 | ui_out_field_string (uiout, "what", b->dll_pathname); | |
1297 | ui_out_text (uiout, "\" "); | |
1298 | @} | |
1299 | @end example | |
1300 | ||
1301 | The following example from @code{print_one_breakpoint} shows how to | |
1302 | use @code{ui_out_field_int} and @code{ui_out_spaces}. The original | |
1303 | code was: | |
1304 | ||
1305 | @example | |
1306 | annotate_field (5); | |
1307 | if (b->forked_inferior_pid != 0) | |
1308 | printf_filtered ("process %d ", b->forked_inferior_pid); | |
1309 | @end example | |
1310 | ||
1311 | It became: | |
1312 | ||
1313 | @example | |
1314 | annotate_field (5); | |
1315 | if (b->forked_inferior_pid != 0) | |
1316 | @{ | |
1317 | ui_out_text (uiout, "process "); | |
1318 | ui_out_field_int (uiout, "what", b->forked_inferior_pid); | |
1319 | ui_out_spaces (uiout, 1); | |
1320 | @} | |
1321 | @end example | |
1322 | ||
1323 | Here's an example of using @code{ui_out_field_string}. The original | |
1324 | code was: | |
1325 | ||
1326 | @example | |
1327 | annotate_field (5); | |
1328 | if (b->exec_pathname != NULL) | |
1329 | printf_filtered ("program \"%s\" ", b->exec_pathname); | |
1330 | @end example | |
1331 | ||
1332 | It became: | |
1333 | ||
1334 | @example | |
1335 | annotate_field (5); | |
1336 | if (b->exec_pathname != NULL) | |
1337 | @{ | |
1338 | ui_out_text (uiout, "program \""); | |
1339 | ui_out_field_string (uiout, "what", b->exec_pathname); | |
1340 | ui_out_text (uiout, "\" "); | |
1341 | @} | |
1342 | @end example | |
1343 | ||
1344 | Finally, here's an example of printing an address. The original code: | |
1345 | ||
1346 | @example | |
1347 | annotate_field (4); | |
1348 | printf_filtered ("%s ", | |
1349 | local_hex_string_custom ((unsigned long) b->address, "08l")); | |
1350 | @end example | |
1351 | ||
1352 | It became: | |
1353 | ||
1354 | @example | |
1355 | annotate_field (4); | |
1356 | ui_out_field_core_addr (uiout, "Address", b->address); | |
1357 | @end example | |
1358 | ||
1359 | ||
c906108c SS |
1360 | @section Console Printing |
1361 | ||
1362 | @section TUI | |
1363 | ||
89437448 | 1364 | @node libgdb |
c906108c | 1365 | |
89437448 AC |
1366 | @chapter libgdb |
1367 | ||
1368 | @section libgdb 1.0 | |
1369 | @cindex @code{libgdb} | |
1370 | @code{libgdb} 1.0 was an abortive project of years ago. The theory was | |
1371 | to provide an API to @value{GDBN}'s functionality. | |
1372 | ||
1373 | @section libgdb 2.0 | |
56caf160 | 1374 | @cindex @code{libgdb} |
89437448 AC |
1375 | @code{libgdb} 2.0 is an ongoing effort to update @value{GDBN} so that is |
1376 | better able to support graphical and other environments. | |
1377 | ||
1378 | Since @code{libgdb} development is on-going, its architecture is still | |
1379 | evolving. The following components have so far been identified: | |
1380 | ||
1381 | @itemize @bullet | |
1382 | @item | |
1383 | Observer - @file{gdb-events.h}. | |
1384 | @item | |
1385 | Builder - @file{ui-out.h} | |
1386 | @item | |
1387 | Event Loop - @file{event-loop.h} | |
1388 | @item | |
1389 | Library - @file{gdb.h} | |
1390 | @end itemize | |
1391 | ||
1392 | The model that ties these components together is described below. | |
1393 | ||
1394 | @section The @code{libgdb} Model | |
1395 | ||
1396 | A client of @code{libgdb} interacts with the library in two ways. | |
1397 | ||
1398 | @itemize @bullet | |
1399 | @item | |
1400 | As an observer (using @file{gdb-events}) receiving notifications from | |
1401 | @code{libgdb} of any internal state changes (break point changes, run | |
1402 | state, etc). | |
1403 | @item | |
1404 | As a client querying @code{libgdb} (using the @file{ui-out} builder) to | |
1405 | obtain various status values from @value{GDBN}. | |
1406 | @end itemize | |
1407 | ||
1408 | Since @code{libgdb} could have multiple clients (e.g. a GUI supporting | |
1409 | the existing @value{GDBN} CLI), those clients must co-operate when | |
1410 | controlling @code{libgdb}. In particular, a client must ensure that | |
1411 | @code{libgdb} is idle (i.e. no other client is using @code{libgdb}) | |
1412 | before responding to a @file{gdb-event} by making a query. | |
1413 | ||
1414 | @section CLI support | |
1415 | ||
1416 | At present @value{GDBN}'s CLI is very much entangled in with the core of | |
1417 | @code{libgdb}. Consequently, a client wishing to include the CLI in | |
1418 | their interface needs to carefully co-ordinate its own and the CLI's | |
1419 | requirements. | |
1420 | ||
1421 | It is suggested that the client set @code{libgdb} up to be bi-modal | |
1422 | (alternate between CLI and client query modes). The notes below sketch | |
1423 | out the theory: | |
1424 | ||
1425 | @itemize @bullet | |
1426 | @item | |
1427 | The client registers itself as an observer of @code{libgdb}. | |
1428 | @item | |
1429 | The client create and install @code{cli-out} builder using its own | |
1430 | versions of the @code{ui-file} @code{gdb_stderr}, @code{gdb_stdtarg} and | |
1431 | @code{gdb_stdout} streams. | |
1432 | @item | |
1433 | The client creates a separate custom @code{ui-out} builder that is only | |
1434 | used while making direct queries to @code{libgdb}. | |
1435 | @end itemize | |
1436 | ||
1437 | When the client receives input intended for the CLI, it simply passes it | |
1438 | along. Since the @code{cli-out} builder is installed by default, all | |
1439 | the CLI output in response to that command is routed (pronounced rooted) | |
1440 | through to the client controlled @code{gdb_stdout} et.@: al.@: streams. | |
1441 | At the same time, the client is kept abreast of internal changes by | |
1442 | virtue of being a @code{libgdb} observer. | |
1443 | ||
1444 | The only restriction on the client is that it must wait until | |
1445 | @code{libgdb} becomes idle before initiating any queries (using the | |
1446 | client's custom builder). | |
1447 | ||
1448 | @section @code{libgdb} components | |
1449 | ||
1450 | @subheading Observer - @file{gdb-events.h} | |
1451 | @file{gdb-events} provides the client with a very raw mechanism that can | |
1452 | be used to implement an observer. At present it only allows for one | |
1453 | observer and that observer must, internally, handle the need to delay | |
1454 | the processing of any event notifications until after @code{libgdb} has | |
1455 | finished the current command. | |
1456 | ||
1457 | @subheading Builder - @file{ui-out.h} | |
1458 | @file{ui-out} provides the infrastructure necessary for a client to | |
1459 | create a builder. That builder is then passed down to @code{libgdb} | |
1460 | when doing any queries. | |
1461 | ||
1462 | @subheading Event Loop - @file{event-loop.h} | |
1463 | @c There could be an entire section on the event-loop | |
1464 | @file{event-loop}, currently non-re-entrant, provides a simple event | |
1465 | loop. A client would need to either plug its self into this loop or, | |
1466 | implement a new event-loop that GDB would use. | |
1467 | ||
1468 | The event-loop will eventually be made re-entrant. This is so that | |
1469 | @value{GDB} can better handle the problem of some commands blocking | |
1470 | instead of returning. | |
1471 | ||
1472 | @subheading Library - @file{gdb.h} | |
1473 | @file{libgdb} is the most obvious component of this system. It provides | |
1474 | the query interface. Each function is parameterized by a @code{ui-out} | |
1475 | builder. The result of the query is constructed using that builder | |
1476 | before the query function returns. | |
c906108c SS |
1477 | |
1478 | @node Symbol Handling | |
1479 | ||
1480 | @chapter Symbol Handling | |
1481 | ||
25822942 | 1482 | Symbols are a key part of @value{GDBN}'s operation. Symbols include variables, |
c906108c SS |
1483 | functions, and types. |
1484 | ||
1485 | @section Symbol Reading | |
1486 | ||
56caf160 EZ |
1487 | @cindex symbol reading |
1488 | @cindex reading of symbols | |
1489 | @cindex symbol files | |
1490 | @value{GDBN} reads symbols from @dfn{symbol files}. The usual symbol | |
1491 | file is the file containing the program which @value{GDBN} is | |
1492 | debugging. @value{GDBN} can be directed to use a different file for | |
1493 | symbols (with the @samp{symbol-file} command), and it can also read | |
1494 | more symbols via the @samp{add-file} and @samp{load} commands, or while | |
1495 | reading symbols from shared libraries. | |
1496 | ||
1497 | @findex find_sym_fns | |
1498 | Symbol files are initially opened by code in @file{symfile.c} using | |
1499 | the BFD library (@pxref{Support Libraries}). BFD identifies the type | |
1500 | of the file by examining its header. @code{find_sym_fns} then uses | |
1501 | this identification to locate a set of symbol-reading functions. | |
1502 | ||
1503 | @findex add_symtab_fns | |
1504 | @cindex @code{sym_fns} structure | |
1505 | @cindex adding a symbol-reading module | |
1506 | Symbol-reading modules identify themselves to @value{GDBN} by calling | |
c906108c SS |
1507 | @code{add_symtab_fns} during their module initialization. The argument |
1508 | to @code{add_symtab_fns} is a @code{struct sym_fns} which contains the | |
1509 | name (or name prefix) of the symbol format, the length of the prefix, | |
1510 | and pointers to four functions. These functions are called at various | |
56caf160 | 1511 | times to process symbol files whose identification matches the specified |
c906108c SS |
1512 | prefix. |
1513 | ||
1514 | The functions supplied by each module are: | |
1515 | ||
1516 | @table @code | |
1517 | @item @var{xyz}_symfile_init(struct sym_fns *sf) | |
1518 | ||
56caf160 | 1519 | @cindex secondary symbol file |
c906108c SS |
1520 | Called from @code{symbol_file_add} when we are about to read a new |
1521 | symbol file. This function should clean up any internal state (possibly | |
1522 | resulting from half-read previous files, for example) and prepare to | |
56caf160 EZ |
1523 | read a new symbol file. Note that the symbol file which we are reading |
1524 | might be a new ``main'' symbol file, or might be a secondary symbol file | |
c906108c SS |
1525 | whose symbols are being added to the existing symbol table. |
1526 | ||
1527 | The argument to @code{@var{xyz}_symfile_init} is a newly allocated | |
1528 | @code{struct sym_fns} whose @code{bfd} field contains the BFD for the | |
1529 | new symbol file being read. Its @code{private} field has been zeroed, | |
1530 | and can be modified as desired. Typically, a struct of private | |
1531 | information will be @code{malloc}'d, and a pointer to it will be placed | |
1532 | in the @code{private} field. | |
1533 | ||
1534 | There is no result from @code{@var{xyz}_symfile_init}, but it can call | |
1535 | @code{error} if it detects an unavoidable problem. | |
1536 | ||
1537 | @item @var{xyz}_new_init() | |
1538 | ||
1539 | Called from @code{symbol_file_add} when discarding existing symbols. | |
56caf160 EZ |
1540 | This function needs only handle the symbol-reading module's internal |
1541 | state; the symbol table data structures visible to the rest of | |
1542 | @value{GDBN} will be discarded by @code{symbol_file_add}. It has no | |
1543 | arguments and no result. It may be called after | |
1544 | @code{@var{xyz}_symfile_init}, if a new symbol table is being read, or | |
1545 | may be called alone if all symbols are simply being discarded. | |
c906108c SS |
1546 | |
1547 | @item @var{xyz}_symfile_read(struct sym_fns *sf, CORE_ADDR addr, int mainline) | |
1548 | ||
1549 | Called from @code{symbol_file_add} to actually read the symbols from a | |
1550 | symbol-file into a set of psymtabs or symtabs. | |
1551 | ||
56caf160 | 1552 | @code{sf} points to the @code{struct sym_fns} originally passed to |
c906108c SS |
1553 | @code{@var{xyz}_sym_init} for possible initialization. @code{addr} is |
1554 | the offset between the file's specified start address and its true | |
1555 | address in memory. @code{mainline} is 1 if this is the main symbol | |
1556 | table being read, and 0 if a secondary symbol file (e.g. shared library | |
1557 | or dynamically loaded file) is being read.@refill | |
1558 | @end table | |
1559 | ||
1560 | In addition, if a symbol-reading module creates psymtabs when | |
1561 | @var{xyz}_symfile_read is called, these psymtabs will contain a pointer | |
1562 | to a function @code{@var{xyz}_psymtab_to_symtab}, which can be called | |
25822942 | 1563 | from any point in the @value{GDBN} symbol-handling code. |
c906108c SS |
1564 | |
1565 | @table @code | |
1566 | @item @var{xyz}_psymtab_to_symtab (struct partial_symtab *pst) | |
1567 | ||
56caf160 | 1568 | Called from @code{psymtab_to_symtab} (or the @code{PSYMTAB_TO_SYMTAB} macro) if |
c906108c SS |
1569 | the psymtab has not already been read in and had its @code{pst->symtab} |
1570 | pointer set. The argument is the psymtab to be fleshed-out into a | |
56caf160 EZ |
1571 | symtab. Upon return, @code{pst->readin} should have been set to 1, and |
1572 | @code{pst->symtab} should contain a pointer to the new corresponding symtab, or | |
c906108c SS |
1573 | zero if there were no symbols in that part of the symbol file. |
1574 | @end table | |
1575 | ||
1576 | @section Partial Symbol Tables | |
1577 | ||
56caf160 | 1578 | @value{GDBN} has three types of symbol tables: |
c906108c SS |
1579 | |
1580 | @itemize @bullet | |
56caf160 EZ |
1581 | @cindex full symbol table |
1582 | @cindex symtabs | |
1583 | @item | |
1584 | Full symbol tables (@dfn{symtabs}). These contain the main | |
1585 | information about symbols and addresses. | |
c906108c | 1586 | |
56caf160 EZ |
1587 | @cindex psymtabs |
1588 | @item | |
1589 | Partial symbol tables (@dfn{psymtabs}). These contain enough | |
c906108c SS |
1590 | information to know when to read the corresponding part of the full |
1591 | symbol table. | |
1592 | ||
56caf160 EZ |
1593 | @cindex minimal symbol table |
1594 | @cindex minsymtabs | |
1595 | @item | |
1596 | Minimal symbol tables (@dfn{msymtabs}). These contain information | |
c906108c | 1597 | gleaned from non-debugging symbols. |
c906108c SS |
1598 | @end itemize |
1599 | ||
56caf160 | 1600 | @cindex partial symbol table |
c906108c SS |
1601 | This section describes partial symbol tables. |
1602 | ||
1603 | A psymtab is constructed by doing a very quick pass over an executable | |
1604 | file's debugging information. Small amounts of information are | |
56caf160 | 1605 | extracted---enough to identify which parts of the symbol table will |
c906108c | 1606 | need to be re-read and fully digested later, when the user needs the |
25822942 | 1607 | information. The speed of this pass causes @value{GDBN} to start up very |
c906108c SS |
1608 | quickly. Later, as the detailed rereading occurs, it occurs in small |
1609 | pieces, at various times, and the delay therefrom is mostly invisible to | |
1610 | the user. | |
1611 | @c (@xref{Symbol Reading}.) | |
1612 | ||
1613 | The symbols that show up in a file's psymtab should be, roughly, those | |
1614 | visible to the debugger's user when the program is not running code from | |
1615 | that file. These include external symbols and types, static symbols and | |
56caf160 | 1616 | types, and @code{enum} values declared at file scope. |
c906108c SS |
1617 | |
1618 | The psymtab also contains the range of instruction addresses that the | |
1619 | full symbol table would represent. | |
1620 | ||
56caf160 EZ |
1621 | @cindex finding a symbol |
1622 | @cindex symbol lookup | |
c906108c SS |
1623 | The idea is that there are only two ways for the user (or much of the |
1624 | code in the debugger) to reference a symbol: | |
1625 | ||
1626 | @itemize @bullet | |
56caf160 EZ |
1627 | @findex find_pc_function |
1628 | @findex find_pc_line | |
1629 | @item | |
1630 | By its address (e.g. execution stops at some address which is inside a | |
1631 | function in this file). The address will be noticed to be in the | |
1632 | range of this psymtab, and the full symtab will be read in. | |
1633 | @code{find_pc_function}, @code{find_pc_line}, and other | |
1634 | @code{find_pc_@dots{}} functions handle this. | |
c906108c | 1635 | |
56caf160 EZ |
1636 | @cindex lookup_symbol |
1637 | @item | |
1638 | By its name | |
c906108c SS |
1639 | (e.g. the user asks to print a variable, or set a breakpoint on a |
1640 | function). Global names and file-scope names will be found in the | |
1641 | psymtab, which will cause the symtab to be pulled in. Local names will | |
1642 | have to be qualified by a global name, or a file-scope name, in which | |
1643 | case we will have already read in the symtab as we evaluated the | |
56caf160 | 1644 | qualifier. Or, a local symbol can be referenced when we are ``in'' a |
c906108c SS |
1645 | local scope, in which case the first case applies. @code{lookup_symbol} |
1646 | does most of the work here. | |
c906108c SS |
1647 | @end itemize |
1648 | ||
1649 | The only reason that psymtabs exist is to cause a symtab to be read in | |
1650 | at the right moment. Any symbol that can be elided from a psymtab, | |
1651 | while still causing that to happen, should not appear in it. Since | |
1652 | psymtabs don't have the idea of scope, you can't put local symbols in | |
1653 | them anyway. Psymtabs don't have the idea of the type of a symbol, | |
1654 | either, so types need not appear, unless they will be referenced by | |
1655 | name. | |
1656 | ||
56caf160 EZ |
1657 | It is a bug for @value{GDBN} to behave one way when only a psymtab has |
1658 | been read, and another way if the corresponding symtab has been read | |
1659 | in. Such bugs are typically caused by a psymtab that does not contain | |
1660 | all the visible symbols, or which has the wrong instruction address | |
1661 | ranges. | |
c906108c | 1662 | |
56caf160 | 1663 | The psymtab for a particular section of a symbol file (objfile) could be |
c906108c SS |
1664 | thrown away after the symtab has been read in. The symtab should always |
1665 | be searched before the psymtab, so the psymtab will never be used (in a | |
1666 | bug-free environment). Currently, psymtabs are allocated on an obstack, | |
1667 | and all the psymbols themselves are allocated in a pair of large arrays | |
1668 | on an obstack, so there is little to be gained by trying to free them | |
1669 | unless you want to do a lot more work. | |
1670 | ||
1671 | @section Types | |
1672 | ||
56caf160 | 1673 | @unnumberedsubsec Fundamental Types (e.g., @code{FT_VOID}, @code{FT_BOOLEAN}). |
c906108c | 1674 | |
56caf160 | 1675 | @cindex fundamental types |
25822942 | 1676 | These are the fundamental types that @value{GDBN} uses internally. Fundamental |
c906108c SS |
1677 | types from the various debugging formats (stabs, ELF, etc) are mapped |
1678 | into one of these. They are basically a union of all fundamental types | |
56caf160 EZ |
1679 | that @value{GDBN} knows about for all the languages that @value{GDBN} |
1680 | knows about. | |
c906108c | 1681 | |
56caf160 | 1682 | @unnumberedsubsec Type Codes (e.g., @code{TYPE_CODE_PTR}, @code{TYPE_CODE_ARRAY}). |
c906108c | 1683 | |
56caf160 EZ |
1684 | @cindex type codes |
1685 | Each time @value{GDBN} builds an internal type, it marks it with one | |
1686 | of these types. The type may be a fundamental type, such as | |
1687 | @code{TYPE_CODE_INT}, or a derived type, such as @code{TYPE_CODE_PTR} | |
1688 | which is a pointer to another type. Typically, several @code{FT_*} | |
1689 | types map to one @code{TYPE_CODE_*} type, and are distinguished by | |
1690 | other members of the type struct, such as whether the type is signed | |
1691 | or unsigned, and how many bits it uses. | |
c906108c | 1692 | |
56caf160 | 1693 | @unnumberedsubsec Builtin Types (e.g., @code{builtin_type_void}, @code{builtin_type_char}). |
c906108c SS |
1694 | |
1695 | These are instances of type structs that roughly correspond to | |
56caf160 EZ |
1696 | fundamental types and are created as global types for @value{GDBN} to |
1697 | use for various ugly historical reasons. We eventually want to | |
1698 | eliminate these. Note for example that @code{builtin_type_int} | |
1699 | initialized in @file{gdbtypes.c} is basically the same as a | |
1700 | @code{TYPE_CODE_INT} type that is initialized in @file{c-lang.c} for | |
1701 | an @code{FT_INTEGER} fundamental type. The difference is that the | |
1702 | @code{builtin_type} is not associated with any particular objfile, and | |
1703 | only one instance exists, while @file{c-lang.c} builds as many | |
1704 | @code{TYPE_CODE_INT} types as needed, with each one associated with | |
1705 | some particular objfile. | |
c906108c SS |
1706 | |
1707 | @section Object File Formats | |
56caf160 | 1708 | @cindex object file formats |
c906108c SS |
1709 | |
1710 | @subsection a.out | |
1711 | ||
56caf160 EZ |
1712 | @cindex @code{a.out} format |
1713 | The @code{a.out} format is the original file format for Unix. It | |
1714 | consists of three sections: @code{text}, @code{data}, and @code{bss}, | |
1715 | which are for program code, initialized data, and uninitialized data, | |
1716 | respectively. | |
c906108c | 1717 | |
56caf160 | 1718 | The @code{a.out} format is so simple that it doesn't have any reserved |
c906108c | 1719 | place for debugging information. (Hey, the original Unix hackers used |
56caf160 EZ |
1720 | @samp{adb}, which is a machine-language debugger!) The only debugging |
1721 | format for @code{a.out} is stabs, which is encoded as a set of normal | |
c906108c SS |
1722 | symbols with distinctive attributes. |
1723 | ||
56caf160 | 1724 | The basic @code{a.out} reader is in @file{dbxread.c}. |
c906108c SS |
1725 | |
1726 | @subsection COFF | |
1727 | ||
56caf160 | 1728 | @cindex COFF format |
c906108c SS |
1729 | The COFF format was introduced with System V Release 3 (SVR3) Unix. |
1730 | COFF files may have multiple sections, each prefixed by a header. The | |
1731 | number of sections is limited. | |
1732 | ||
1733 | The COFF specification includes support for debugging. Although this | |
1734 | was a step forward, the debugging information was woefully limited. For | |
1735 | instance, it was not possible to represent code that came from an | |
1736 | included file. | |
1737 | ||
1738 | The COFF reader is in @file{coffread.c}. | |
1739 | ||
1740 | @subsection ECOFF | |
1741 | ||
56caf160 | 1742 | @cindex ECOFF format |
c906108c SS |
1743 | ECOFF is an extended COFF originally introduced for Mips and Alpha |
1744 | workstations. | |
1745 | ||
1746 | The basic ECOFF reader is in @file{mipsread.c}. | |
1747 | ||
1748 | @subsection XCOFF | |
1749 | ||
56caf160 | 1750 | @cindex XCOFF format |
c906108c SS |
1751 | The IBM RS/6000 running AIX uses an object file format called XCOFF. |
1752 | The COFF sections, symbols, and line numbers are used, but debugging | |
56caf160 EZ |
1753 | symbols are @code{dbx}-style stabs whose strings are located in the |
1754 | @code{.debug} section (rather than the string table). For more | |
1755 | information, see @ref{Top,,,stabs,The Stabs Debugging Format}. | |
c906108c SS |
1756 | |
1757 | The shared library scheme has a clean interface for figuring out what | |
1758 | shared libraries are in use, but the catch is that everything which | |
1759 | refers to addresses (symbol tables and breakpoints at least) needs to be | |
1760 | relocated for both shared libraries and the main executable. At least | |
1761 | using the standard mechanism this can only be done once the program has | |
1762 | been run (or the core file has been read). | |
1763 | ||
1764 | @subsection PE | |
1765 | ||
56caf160 EZ |
1766 | @cindex PE-COFF format |
1767 | Windows 95 and NT use the PE (@dfn{Portable Executable}) format for their | |
c906108c SS |
1768 | executables. PE is basically COFF with additional headers. |
1769 | ||
25822942 | 1770 | While BFD includes special PE support, @value{GDBN} needs only the basic |
c906108c SS |
1771 | COFF reader. |
1772 | ||
1773 | @subsection ELF | |
1774 | ||
56caf160 | 1775 | @cindex ELF format |
c906108c SS |
1776 | The ELF format came with System V Release 4 (SVR4) Unix. ELF is similar |
1777 | to COFF in being organized into a number of sections, but it removes | |
1778 | many of COFF's limitations. | |
1779 | ||
1780 | The basic ELF reader is in @file{elfread.c}. | |
1781 | ||
1782 | @subsection SOM | |
1783 | ||
56caf160 | 1784 | @cindex SOM format |
c906108c SS |
1785 | SOM is HP's object file and debug format (not to be confused with IBM's |
1786 | SOM, which is a cross-language ABI). | |
1787 | ||
1788 | The SOM reader is in @file{hpread.c}. | |
1789 | ||
1790 | @subsection Other File Formats | |
1791 | ||
56caf160 | 1792 | @cindex Netware Loadable Module format |
25822942 | 1793 | Other file formats that have been supported by @value{GDBN} include Netware |
4a98ee0e | 1794 | Loadable Modules (@file{nlmread.c}). |
c906108c SS |
1795 | |
1796 | @section Debugging File Formats | |
1797 | ||
1798 | This section describes characteristics of debugging information that | |
1799 | are independent of the object file format. | |
1800 | ||
1801 | @subsection stabs | |
1802 | ||
56caf160 | 1803 | @cindex stabs debugging info |
c906108c SS |
1804 | @code{stabs} started out as special symbols within the @code{a.out} |
1805 | format. Since then, it has been encapsulated into other file | |
1806 | formats, such as COFF and ELF. | |
1807 | ||
1808 | While @file{dbxread.c} does some of the basic stab processing, | |
1809 | including for encapsulated versions, @file{stabsread.c} does | |
1810 | the real work. | |
1811 | ||
1812 | @subsection COFF | |
1813 | ||
56caf160 | 1814 | @cindex COFF debugging info |
c906108c SS |
1815 | The basic COFF definition includes debugging information. The level |
1816 | of support is minimal and non-extensible, and is not often used. | |
1817 | ||
1818 | @subsection Mips debug (Third Eye) | |
1819 | ||
56caf160 | 1820 | @cindex ECOFF debugging info |
c906108c SS |
1821 | ECOFF includes a definition of a special debug format. |
1822 | ||
1823 | The file @file{mdebugread.c} implements reading for this format. | |
1824 | ||
1825 | @subsection DWARF 1 | |
1826 | ||
56caf160 | 1827 | @cindex DWARF 1 debugging info |
c906108c SS |
1828 | DWARF 1 is a debugging format that was originally designed to be |
1829 | used with ELF in SVR4 systems. | |
1830 | ||
1831 | @c CHILL_PRODUCER | |
1832 | @c GCC_PRODUCER | |
1833 | @c GPLUS_PRODUCER | |
1834 | @c LCC_PRODUCER | |
1835 | @c If defined, these are the producer strings in a DWARF 1 file. All of | |
1836 | @c these have reasonable defaults already. | |
1837 | ||
1838 | The DWARF 1 reader is in @file{dwarfread.c}. | |
1839 | ||
1840 | @subsection DWARF 2 | |
1841 | ||
56caf160 | 1842 | @cindex DWARF 2 debugging info |
c906108c SS |
1843 | DWARF 2 is an improved but incompatible version of DWARF 1. |
1844 | ||
1845 | The DWARF 2 reader is in @file{dwarf2read.c}. | |
1846 | ||
1847 | @subsection SOM | |
1848 | ||
56caf160 | 1849 | @cindex SOM debugging info |
c906108c SS |
1850 | Like COFF, the SOM definition includes debugging information. |
1851 | ||
25822942 | 1852 | @section Adding a New Symbol Reader to @value{GDBN} |
c906108c | 1853 | |
56caf160 EZ |
1854 | @cindex adding debugging info reader |
1855 | If you are using an existing object file format (@code{a.out}, COFF, ELF, etc), | |
c906108c SS |
1856 | there is probably little to be done. |
1857 | ||
1858 | If you need to add a new object file format, you must first add it to | |
1859 | BFD. This is beyond the scope of this document. | |
1860 | ||
1861 | You must then arrange for the BFD code to provide access to the | |
25822942 | 1862 | debugging symbols. Generally @value{GDBN} will have to call swapping routines |
c906108c | 1863 | from BFD and a few other BFD internal routines to locate the debugging |
25822942 | 1864 | information. As much as possible, @value{GDBN} should not depend on the BFD |
c906108c SS |
1865 | internal data structures. |
1866 | ||
1867 | For some targets (e.g., COFF), there is a special transfer vector used | |
1868 | to call swapping routines, since the external data structures on various | |
1869 | platforms have different sizes and layouts. Specialized routines that | |
1870 | will only ever be implemented by one object file format may be called | |
1871 | directly. This interface should be described in a file | |
56caf160 | 1872 | @file{bfd/lib@var{xyz}.h}, which is included by @value{GDBN}. |
c906108c SS |
1873 | |
1874 | ||
1875 | @node Language Support | |
1876 | ||
1877 | @chapter Language Support | |
1878 | ||
56caf160 EZ |
1879 | @cindex language support |
1880 | @value{GDBN}'s language support is mainly driven by the symbol reader, | |
1881 | although it is possible for the user to set the source language | |
1882 | manually. | |
c906108c | 1883 | |
56caf160 EZ |
1884 | @value{GDBN} chooses the source language by looking at the extension |
1885 | of the file recorded in the debug info; @file{.c} means C, @file{.f} | |
1886 | means Fortran, etc. It may also use a special-purpose language | |
1887 | identifier if the debug format supports it, like with DWARF. | |
c906108c | 1888 | |
25822942 | 1889 | @section Adding a Source Language to @value{GDBN} |
c906108c | 1890 | |
56caf160 EZ |
1891 | @cindex adding source language |
1892 | To add other languages to @value{GDBN}'s expression parser, follow the | |
1893 | following steps: | |
c906108c SS |
1894 | |
1895 | @table @emph | |
1896 | @item Create the expression parser. | |
1897 | ||
56caf160 | 1898 | @cindex expression parser |
c906108c | 1899 | This should reside in a file @file{@var{lang}-exp.y}. Routines for |
56caf160 | 1900 | building parsed expressions into a @code{union exp_element} list are in |
c906108c SS |
1901 | @file{parse.c}. |
1902 | ||
56caf160 | 1903 | @cindex language parser |
c906108c SS |
1904 | Since we can't depend upon everyone having Bison, and YACC produces |
1905 | parsers that define a bunch of global names, the following lines | |
56caf160 | 1906 | @strong{must} be included at the top of the YACC parser, to prevent the |
c906108c SS |
1907 | various parsers from defining the same global names: |
1908 | ||
1909 | @example | |
56caf160 EZ |
1910 | #define yyparse @var{lang}_parse |
1911 | #define yylex @var{lang}_lex | |
1912 | #define yyerror @var{lang}_error | |
1913 | #define yylval @var{lang}_lval | |
1914 | #define yychar @var{lang}_char | |
1915 | #define yydebug @var{lang}_debug | |
1916 | #define yypact @var{lang}_pact | |
1917 | #define yyr1 @var{lang}_r1 | |
1918 | #define yyr2 @var{lang}_r2 | |
1919 | #define yydef @var{lang}_def | |
1920 | #define yychk @var{lang}_chk | |
1921 | #define yypgo @var{lang}_pgo | |
1922 | #define yyact @var{lang}_act | |
1923 | #define yyexca @var{lang}_exca | |
1924 | #define yyerrflag @var{lang}_errflag | |
1925 | #define yynerrs @var{lang}_nerrs | |
c906108c SS |
1926 | @end example |
1927 | ||
1928 | At the bottom of your parser, define a @code{struct language_defn} and | |
1929 | initialize it with the right values for your language. Define an | |
1930 | @code{initialize_@var{lang}} routine and have it call | |
25822942 | 1931 | @samp{add_language(@var{lang}_language_defn)} to tell the rest of @value{GDBN} |
c906108c SS |
1932 | that your language exists. You'll need some other supporting variables |
1933 | and functions, which will be used via pointers from your | |
1934 | @code{@var{lang}_language_defn}. See the declaration of @code{struct | |
1935 | language_defn} in @file{language.h}, and the other @file{*-exp.y} files, | |
1936 | for more information. | |
1937 | ||
1938 | @item Add any evaluation routines, if necessary | |
1939 | ||
56caf160 EZ |
1940 | @cindex expression evaluation routines |
1941 | @findex evaluate_subexp | |
1942 | @findex prefixify_subexp | |
1943 | @findex length_of_subexp | |
c906108c SS |
1944 | If you need new opcodes (that represent the operations of the language), |
1945 | add them to the enumerated type in @file{expression.h}. Add support | |
56caf160 EZ |
1946 | code for these operations in the @code{evaluate_subexp} function |
1947 | defined in the file @file{eval.c}. Add cases | |
c906108c | 1948 | for new opcodes in two functions from @file{parse.c}: |
56caf160 | 1949 | @code{prefixify_subexp} and @code{length_of_subexp}. These compute |
c906108c SS |
1950 | the number of @code{exp_element}s that a given operation takes up. |
1951 | ||
1952 | @item Update some existing code | |
1953 | ||
1954 | Add an enumerated identifier for your language to the enumerated type | |
1955 | @code{enum language} in @file{defs.h}. | |
1956 | ||
1957 | Update the routines in @file{language.c} so your language is included. | |
1958 | These routines include type predicates and such, which (in some cases) | |
1959 | are language dependent. If your language does not appear in the switch | |
1960 | statement, an error is reported. | |
1961 | ||
56caf160 | 1962 | @vindex current_language |
c906108c SS |
1963 | Also included in @file{language.c} is the code that updates the variable |
1964 | @code{current_language}, and the routines that translate the | |
1965 | @code{language_@var{lang}} enumerated identifier into a printable | |
1966 | string. | |
1967 | ||
56caf160 | 1968 | @findex _initialize_language |
c906108c SS |
1969 | Update the function @code{_initialize_language} to include your |
1970 | language. This function picks the default language upon startup, so is | |
25822942 | 1971 | dependent upon which languages that @value{GDBN} is built for. |
c906108c | 1972 | |
56caf160 | 1973 | @findex allocate_symtab |
c906108c SS |
1974 | Update @code{allocate_symtab} in @file{symfile.c} and/or symbol-reading |
1975 | code so that the language of each symtab (source file) is set properly. | |
1976 | This is used to determine the language to use at each stack frame level. | |
1977 | Currently, the language is set based upon the extension of the source | |
1978 | file. If the language can be better inferred from the symbol | |
1979 | information, please set the language of the symtab in the symbol-reading | |
1980 | code. | |
1981 | ||
56caf160 EZ |
1982 | @findex print_subexp |
1983 | @findex op_print_tab | |
1984 | Add helper code to @code{print_subexp} (in @file{expprint.c}) to handle any new | |
c906108c SS |
1985 | expression opcodes you have added to @file{expression.h}. Also, add the |
1986 | printed representations of your operators to @code{op_print_tab}. | |
1987 | ||
1988 | @item Add a place of call | |
1989 | ||
56caf160 | 1990 | @findex parse_exp_1 |
c906108c | 1991 | Add a call to @code{@var{lang}_parse()} and @code{@var{lang}_error} in |
56caf160 | 1992 | @code{parse_exp_1} (defined in @file{parse.c}). |
c906108c SS |
1993 | |
1994 | @item Use macros to trim code | |
1995 | ||
56caf160 | 1996 | @cindex trimming language-dependent code |
25822942 DB |
1997 | The user has the option of building @value{GDBN} for some or all of the |
1998 | languages. If the user decides to build @value{GDBN} for the language | |
c906108c SS |
1999 | @var{lang}, then every file dependent on @file{language.h} will have the |
2000 | macro @code{_LANG_@var{lang}} defined in it. Use @code{#ifdef}s to | |
2001 | leave out large routines that the user won't need if he or she is not | |
2002 | using your language. | |
2003 | ||
25822942 | 2004 | Note that you do not need to do this in your YACC parser, since if @value{GDBN} |
c906108c | 2005 | is not build for @var{lang}, then @file{@var{lang}-exp.tab.o} (the |
25822942 | 2006 | compiled form of your parser) is not linked into @value{GDBN} at all. |
c906108c | 2007 | |
56caf160 EZ |
2008 | See the file @file{configure.in} for how @value{GDBN} is configured |
2009 | for different languages. | |
c906108c SS |
2010 | |
2011 | @item Edit @file{Makefile.in} | |
2012 | ||
2013 | Add dependencies in @file{Makefile.in}. Make sure you update the macro | |
2014 | variables such as @code{HFILES} and @code{OBJS}, otherwise your code may | |
2015 | not get linked in, or, worse yet, it may not get @code{tar}red into the | |
2016 | distribution! | |
c906108c SS |
2017 | @end table |
2018 | ||
2019 | ||
2020 | @node Host Definition | |
2021 | ||
2022 | @chapter Host Definition | |
2023 | ||
af6c57ea AC |
2024 | @emph{Maintainer's note: In theory, new targets no longer need to use |
2025 | the host framework described below. Instead it should be possible to | |
2026 | handle everything using autoconf. Patches eliminating this framework | |
2027 | welcome.} | |
2028 | ||
56caf160 | 2029 | With the advent of Autoconf, it's rarely necessary to have host |
c906108c SS |
2030 | definition machinery anymore. |
2031 | ||
2032 | @section Adding a New Host | |
2033 | ||
56caf160 EZ |
2034 | @cindex adding a new host |
2035 | @cindex host, adding | |
2036 | Most of @value{GDBN}'s host configuration support happens via | |
2037 | Autoconf. New host-specific definitions should be rarely needed. | |
2038 | @value{GDBN} still uses the host-specific definitions and files listed | |
2039 | below, but these mostly exist for historical reasons, and should | |
2040 | eventually disappear. | |
c906108c | 2041 | |
25822942 | 2042 | Several files control @value{GDBN}'s configuration for host systems: |
c906108c SS |
2043 | |
2044 | @table @file | |
56caf160 | 2045 | @vindex XDEPFILES |
c906108c SS |
2046 | @item gdb/config/@var{arch}/@var{xyz}.mh |
2047 | Specifies Makefile fragments needed when hosting on machine @var{xyz}. | |
2048 | In particular, this lists the required machine-dependent object files, | |
2049 | by defining @samp{XDEPFILES=@dots{}}. Also specifies the header file | |
2050 | which describes host @var{xyz}, by defining @code{XM_FILE= | |
2051 | xm-@var{xyz}.h}. You can also define @code{CC}, @code{SYSV_DEFINE}, | |
2052 | @code{XM_CFLAGS}, @code{XM_ADD_FILES}, @code{XM_CLIBS}, @code{XM_CDEPS}, | |
2053 | etc.; see @file{Makefile.in}. | |
2054 | ||
2055 | @item gdb/config/@var{arch}/xm-@var{xyz}.h | |
56caf160 | 2056 | (@file{xm.h} is a link to this file, created by @code{configure}). Contains C |
c906108c SS |
2057 | macro definitions describing the host system environment, such as byte |
2058 | order, host C compiler and library. | |
2059 | ||
2060 | @item gdb/@var{xyz}-xdep.c | |
2061 | Contains any miscellaneous C code required for this machine as a host. | |
2062 | On most machines it doesn't exist at all. If it does exist, put | |
2063 | @file{@var{xyz}-xdep.o} into the @code{XDEPFILES} line in | |
2064 | @file{gdb/config/@var{arch}/@var{xyz}.mh}. | |
c906108c SS |
2065 | @end table |
2066 | ||
2067 | @subheading Generic Host Support Files | |
2068 | ||
56caf160 | 2069 | @cindex generic host support |
c906108c SS |
2070 | There are some ``generic'' versions of routines that can be used by |
2071 | various systems. These can be customized in various ways by macros | |
2072 | defined in your @file{xm-@var{xyz}.h} file. If these routines work for | |
2073 | the @var{xyz} host, you can just include the generic file's name (with | |
2074 | @samp{.o}, not @samp{.c}) in @code{XDEPFILES}. | |
2075 | ||
2076 | Otherwise, if your machine needs custom support routines, you will need | |
2077 | to write routines that perform the same functions as the generic file. | |
2078 | Put them into @code{@var{xyz}-xdep.c}, and put @code{@var{xyz}-xdep.o} | |
2079 | into @code{XDEPFILES}. | |
2080 | ||
2081 | @table @file | |
56caf160 EZ |
2082 | @cindex remote debugging support |
2083 | @cindex serial line support | |
c906108c SS |
2084 | @item ser-unix.c |
2085 | This contains serial line support for Unix systems. This is always | |
2086 | included, via the makefile variable @code{SER_HARDWIRE}; override this | |
2087 | variable in the @file{.mh} file to avoid it. | |
2088 | ||
2089 | @item ser-go32.c | |
2090 | This contains serial line support for 32-bit programs running under DOS, | |
56caf160 | 2091 | using the DJGPP (a.k.a.@: GO32) execution environment. |
c906108c | 2092 | |
56caf160 | 2093 | @cindex TCP remote support |
c906108c SS |
2094 | @item ser-tcp.c |
2095 | This contains generic TCP support using sockets. | |
c906108c SS |
2096 | @end table |
2097 | ||
2098 | @section Host Conditionals | |
2099 | ||
56caf160 EZ |
2100 | When @value{GDBN} is configured and compiled, various macros are |
2101 | defined or left undefined, to control compilation based on the | |
2102 | attributes of the host system. These macros and their meanings (or if | |
2103 | the meaning is not documented here, then one of the source files where | |
2104 | they are used is indicated) are: | |
c906108c | 2105 | |
56caf160 | 2106 | @ftable @code |
25822942 | 2107 | @item @value{GDBN}INIT_FILENAME |
56caf160 EZ |
2108 | The default name of @value{GDBN}'s initialization file (normally |
2109 | @file{.gdbinit}). | |
c906108c | 2110 | |
cce74817 JM |
2111 | @item NO_STD_REGS |
2112 | This macro is deprecated. | |
2113 | ||
c906108c SS |
2114 | @item NO_SYS_FILE |
2115 | Define this if your system does not have a @code{<sys/file.h>}. | |
2116 | ||
2117 | @item SIGWINCH_HANDLER | |
2118 | If your host defines @code{SIGWINCH}, you can define this to be the name | |
2119 | of a function to be called if @code{SIGWINCH} is received. | |
2120 | ||
2121 | @item SIGWINCH_HANDLER_BODY | |
2122 | Define this to expand into code that will define the function named by | |
2123 | the expansion of @code{SIGWINCH_HANDLER}. | |
2124 | ||
2125 | @item ALIGN_STACK_ON_STARTUP | |
56caf160 | 2126 | @cindex stack alignment |
c906108c SS |
2127 | Define this if your system is of a sort that will crash in |
2128 | @code{tgetent} if the stack happens not to be longword-aligned when | |
2129 | @code{main} is called. This is a rare situation, but is known to occur | |
2130 | on several different types of systems. | |
2131 | ||
2132 | @item CRLF_SOURCE_FILES | |
56caf160 | 2133 | @cindex DOS text files |
c906108c SS |
2134 | Define this if host files use @code{\r\n} rather than @code{\n} as a |
2135 | line terminator. This will cause source file listings to omit @code{\r} | |
56caf160 EZ |
2136 | characters when printing and it will allow @code{\r\n} line endings of files |
2137 | which are ``sourced'' by gdb. It must be possible to open files in binary | |
c906108c SS |
2138 | mode using @code{O_BINARY} or, for fopen, @code{"rb"}. |
2139 | ||
2140 | @item DEFAULT_PROMPT | |
56caf160 | 2141 | @cindex prompt |
c906108c SS |
2142 | The default value of the prompt string (normally @code{"(gdb) "}). |
2143 | ||
2144 | @item DEV_TTY | |
56caf160 | 2145 | @cindex terminal device |
c906108c SS |
2146 | The name of the generic TTY device, defaults to @code{"/dev/tty"}. |
2147 | ||
2148 | @item FCLOSE_PROVIDED | |
2149 | Define this if the system declares @code{fclose} in the headers included | |
2150 | in @code{defs.h}. This isn't needed unless your compiler is unusually | |
2151 | anal. | |
2152 | ||
2153 | @item FOPEN_RB | |
2154 | Define this if binary files are opened the same way as text files. | |
2155 | ||
2156 | @item GETENV_PROVIDED | |
2157 | Define this if the system declares @code{getenv} in its headers included | |
56caf160 | 2158 | in @code{defs.h}. This isn't needed unless your compiler is unusually |
c906108c SS |
2159 | anal. |
2160 | ||
2161 | @item HAVE_MMAP | |
56caf160 | 2162 | @findex mmap |
c906108c SS |
2163 | In some cases, use the system call @code{mmap} for reading symbol |
2164 | tables. For some machines this allows for sharing and quick updates. | |
2165 | ||
c906108c SS |
2166 | @item HAVE_TERMIO |
2167 | Define this if the host system has @code{termio.h}. | |
2168 | ||
c906108c | 2169 | @item INT_MAX |
9742079a EZ |
2170 | @itemx INT_MIN |
2171 | @itemx LONG_MAX | |
2172 | @itemx UINT_MAX | |
2173 | @itemx ULONG_MAX | |
c906108c SS |
2174 | Values for host-side constants. |
2175 | ||
2176 | @item ISATTY | |
2177 | Substitute for isatty, if not available. | |
2178 | ||
2179 | @item LONGEST | |
2180 | This is the longest integer type available on the host. If not defined, | |
2181 | it will default to @code{long long} or @code{long}, depending on | |
2182 | @code{CC_HAS_LONG_LONG}. | |
2183 | ||
2184 | @item CC_HAS_LONG_LONG | |
56caf160 EZ |
2185 | @cindex @code{long long} data type |
2186 | Define this if the host C compiler supports @code{long long}. This is set | |
2187 | by the @code{configure} script. | |
c906108c SS |
2188 | |
2189 | @item PRINTF_HAS_LONG_LONG | |
2190 | Define this if the host can handle printing of long long integers via | |
56caf160 EZ |
2191 | the printf format conversion specifier @code{ll}. This is set by the |
2192 | @code{configure} script. | |
c906108c SS |
2193 | |
2194 | @item HAVE_LONG_DOUBLE | |
56caf160 EZ |
2195 | Define this if the host C compiler supports @code{long double}. This is |
2196 | set by the @code{configure} script. | |
c906108c SS |
2197 | |
2198 | @item PRINTF_HAS_LONG_DOUBLE | |
2199 | Define this if the host can handle printing of long double float-point | |
56caf160 EZ |
2200 | numbers via the printf format conversion specifier @code{Lg}. This is |
2201 | set by the @code{configure} script. | |
c906108c SS |
2202 | |
2203 | @item SCANF_HAS_LONG_DOUBLE | |
2204 | Define this if the host can handle the parsing of long double | |
56caf160 EZ |
2205 | float-point numbers via the scanf format conversion specifier |
2206 | @code{Lg}. This is set by the @code{configure} script. | |
c906108c SS |
2207 | |
2208 | @item LSEEK_NOT_LINEAR | |
2209 | Define this if @code{lseek (n)} does not necessarily move to byte number | |
2210 | @code{n} in the file. This is only used when reading source files. It | |
2211 | is normally faster to define @code{CRLF_SOURCE_FILES} when possible. | |
2212 | ||
2213 | @item L_SET | |
56caf160 EZ |
2214 | This macro is used as the argument to @code{lseek} (or, most commonly, |
2215 | @code{bfd_seek}). FIXME, should be replaced by SEEK_SET instead, | |
2216 | which is the POSIX equivalent. | |
c906108c | 2217 | |
c906108c SS |
2218 | @item MALLOC_INCOMPATIBLE |
2219 | Define this if the system's prototype for @code{malloc} differs from the | |
56caf160 | 2220 | @sc{ansi} definition. |
c906108c SS |
2221 | |
2222 | @item MMAP_BASE_ADDRESS | |
2223 | When using HAVE_MMAP, the first mapping should go at this address. | |
2224 | ||
2225 | @item MMAP_INCREMENT | |
2226 | when using HAVE_MMAP, this is the increment between mappings. | |
2227 | ||
c906108c SS |
2228 | @item NORETURN |
2229 | If defined, this should be one or more tokens, such as @code{volatile}, | |
2230 | that can be used in both the declaration and definition of functions to | |
2231 | indicate that they never return. The default is already set correctly | |
2232 | if compiling with GCC. This will almost never need to be defined. | |
2233 | ||
2234 | @item ATTR_NORETURN | |
2235 | If defined, this should be one or more tokens, such as | |
2236 | @code{__attribute__ ((noreturn))}, that can be used in the declarations | |
2237 | of functions to indicate that they never return. The default is already | |
2238 | set correctly if compiling with GCC. This will almost never need to be | |
2239 | defined. | |
2240 | ||
7a292a7a | 2241 | @item USE_GENERIC_DUMMY_FRAMES |
56caf160 | 2242 | @cindex generic dummy frames |
7a292a7a SS |
2243 | Define this to 1 if the target is using the generic inferior function |
2244 | call code. See @code{blockframe.c} for more information. | |
2245 | ||
c906108c | 2246 | @item USE_MMALLOC |
56caf160 EZ |
2247 | @findex mmalloc |
2248 | @value{GDBN} will use the @code{mmalloc} library for memory allocation | |
2249 | for symbol reading if this symbol is defined. Be careful defining it | |
2250 | since there are systems on which @code{mmalloc} does not work for some | |
2251 | reason. One example is the DECstation, where its RPC library can't | |
2252 | cope with our redefinition of @code{malloc} to call @code{mmalloc}. | |
2253 | When defining @code{USE_MMALLOC}, you will also have to set | |
2254 | @code{MMALLOC} in the Makefile, to point to the @code{mmalloc} library. This | |
2255 | define is set when you configure with @samp{--with-mmalloc}. | |
c906108c SS |
2256 | |
2257 | @item NO_MMCHECK | |
56caf160 | 2258 | @findex mmcheck |
c906108c SS |
2259 | Define this if you are using @code{mmalloc}, but don't want the overhead |
2260 | of checking the heap with @code{mmcheck}. Note that on some systems, | |
56caf160 | 2261 | the C runtime makes calls to @code{malloc} prior to calling @code{main}, and if |
c906108c SS |
2262 | @code{free} is ever called with these pointers after calling |
2263 | @code{mmcheck} to enable checking, a memory corruption abort is certain | |
56caf160 EZ |
2264 | to occur. These systems can still use @code{mmalloc}, but must define |
2265 | @code{NO_MMCHECK}. | |
c906108c SS |
2266 | |
2267 | @item MMCHECK_FORCE | |
2268 | Define this to 1 if the C runtime allocates memory prior to | |
2269 | @code{mmcheck} being called, but that memory is never freed so we don't | |
2270 | have to worry about it triggering a memory corruption abort. The | |
2271 | default is 0, which means that @code{mmcheck} will only install the heap | |
2272 | checking functions if there has not yet been any memory allocation | |
56caf160 | 2273 | calls, and if it fails to install the functions, @value{GDBN} will issue a |
c906108c | 2274 | warning. This is currently defined if you configure using |
56caf160 | 2275 | @samp{--with-mmalloc}. |
c906108c SS |
2276 | |
2277 | @item NO_SIGINTERRUPT | |
56caf160 EZ |
2278 | @findex siginterrupt |
2279 | Define this to indicate that @code{siginterrupt} is not available. | |
c906108c | 2280 | |
c906108c | 2281 | @item SEEK_CUR |
9742079a | 2282 | @itemx SEEK_SET |
56caf160 | 2283 | Define these to appropriate value for the system @code{lseek}, if not already |
c906108c SS |
2284 | defined. |
2285 | ||
2286 | @item STOP_SIGNAL | |
56caf160 EZ |
2287 | This is the signal for stopping @value{GDBN}. Defaults to |
2288 | @code{SIGTSTP}. (Only redefined for the Convex.) | |
c906108c SS |
2289 | |
2290 | @item USE_O_NOCTTY | |
56caf160 | 2291 | Define this if the interior's tty should be opened with the @code{O_NOCTTY} |
c906108c SS |
2292 | flag. (FIXME: This should be a native-only flag, but @file{inflow.c} is |
2293 | always linked in.) | |
2294 | ||
2295 | @item USG | |
2296 | Means that System V (prior to SVR4) include files are in use. (FIXME: | |
2297 | This symbol is abused in @file{infrun.c}, @file{regex.c}, | |
2298 | @file{remote-nindy.c}, and @file{utils.c} for other things, at the | |
2299 | moment.) | |
2300 | ||
2301 | @item lint | |
56caf160 | 2302 | Define this to help placate @code{lint} in some situations. |
c906108c SS |
2303 | |
2304 | @item volatile | |
2305 | Define this to override the defaults of @code{__volatile__} or | |
2306 | @code{/**/}. | |
56caf160 | 2307 | @end ftable |
c906108c SS |
2308 | |
2309 | ||
2310 | @node Target Architecture Definition | |
2311 | ||
2312 | @chapter Target Architecture Definition | |
2313 | ||
56caf160 EZ |
2314 | @cindex target architecture definition |
2315 | @value{GDBN}'s target architecture defines what sort of | |
2316 | machine-language programs @value{GDBN} can work with, and how it works | |
2317 | with them. | |
c906108c | 2318 | |
af6c57ea AC |
2319 | The target architecture object is implemented as the C structure |
2320 | @code{struct gdbarch *}. The structure, and its methods, are generated | |
93c2c750 | 2321 | using the Bourne shell script @file{gdbarch.sh}. |
c906108c SS |
2322 | |
2323 | @section Registers and Memory | |
2324 | ||
56caf160 EZ |
2325 | @value{GDBN}'s model of the target machine is rather simple. |
2326 | @value{GDBN} assumes the machine includes a bank of registers and a | |
2327 | block of memory. Each register may have a different size. | |
c906108c | 2328 | |
56caf160 EZ |
2329 | @value{GDBN} does not have a magical way to match up with the |
2330 | compiler's idea of which registers are which; however, it is critical | |
2331 | that they do match up accurately. The only way to make this work is | |
2332 | to get accurate information about the order that the compiler uses, | |
2333 | and to reflect that in the @code{REGISTER_NAME} and related macros. | |
c906108c | 2334 | |
25822942 | 2335 | @value{GDBN} can handle big-endian, little-endian, and bi-endian architectures. |
c906108c | 2336 | |
93e79dbd JB |
2337 | @section Pointers Are Not Always Addresses |
2338 | @cindex pointer representation | |
2339 | @cindex address representation | |
2340 | @cindex word-addressed machines | |
2341 | @cindex separate data and code address spaces | |
2342 | @cindex spaces, separate data and code address | |
2343 | @cindex address spaces, separate data and code | |
2344 | @cindex code pointers, word-addressed | |
2345 | @cindex converting between pointers and addresses | |
2346 | @cindex D10V addresses | |
2347 | ||
2348 | On almost all 32-bit architectures, the representation of a pointer is | |
2349 | indistinguishable from the representation of some fixed-length number | |
2350 | whose value is the byte address of the object pointed to. On such | |
56caf160 | 2351 | machines, the words ``pointer'' and ``address'' can be used interchangeably. |
93e79dbd JB |
2352 | However, architectures with smaller word sizes are often cramped for |
2353 | address space, so they may choose a pointer representation that breaks this | |
2354 | identity, and allows a larger code address space. | |
2355 | ||
2356 | For example, the Mitsubishi D10V is a 16-bit VLIW processor whose | |
2357 | instructions are 32 bits long@footnote{Some D10V instructions are | |
2358 | actually pairs of 16-bit sub-instructions. However, since you can't | |
2359 | jump into the middle of such a pair, code addresses can only refer to | |
2360 | full 32 bit instructions, which is what matters in this explanation.}. | |
2361 | If the D10V used ordinary byte addresses to refer to code locations, | |
2362 | then the processor would only be able to address 64kb of instructions. | |
2363 | However, since instructions must be aligned on four-byte boundaries, the | |
56caf160 EZ |
2364 | low two bits of any valid instruction's byte address are always |
2365 | zero---byte addresses waste two bits. So instead of byte addresses, | |
2366 | the D10V uses word addresses---byte addresses shifted right two bits---to | |
93e79dbd JB |
2367 | refer to code. Thus, the D10V can use 16-bit words to address 256kb of |
2368 | code space. | |
2369 | ||
2370 | However, this means that code pointers and data pointers have different | |
2371 | forms on the D10V. The 16-bit word @code{0xC020} refers to byte address | |
2372 | @code{0xC020} when used as a data address, but refers to byte address | |
2373 | @code{0x30080} when used as a code address. | |
2374 | ||
2375 | (The D10V also uses separate code and data address spaces, which also | |
2376 | affects the correspondence between pointers and addresses, but we're | |
2377 | going to ignore that here; this example is already too long.) | |
2378 | ||
56caf160 EZ |
2379 | To cope with architectures like this---the D10V is not the only |
2380 | one!---@value{GDBN} tries to distinguish between @dfn{addresses}, which are | |
93e79dbd JB |
2381 | byte numbers, and @dfn{pointers}, which are the target's representation |
2382 | of an address of a particular type of data. In the example above, | |
2383 | @code{0xC020} is the pointer, which refers to one of the addresses | |
2384 | @code{0xC020} or @code{0x30080}, depending on the type imposed upon it. | |
2385 | @value{GDBN} provides functions for turning a pointer into an address | |
2386 | and vice versa, in the appropriate way for the current architecture. | |
2387 | ||
2388 | Unfortunately, since addresses and pointers are identical on almost all | |
2389 | processors, this distinction tends to bit-rot pretty quickly. Thus, | |
2390 | each time you port @value{GDBN} to an architecture which does | |
2391 | distinguish between pointers and addresses, you'll probably need to | |
2392 | clean up some architecture-independent code. | |
2393 | ||
2394 | Here are functions which convert between pointers and addresses: | |
2395 | ||
2396 | @deftypefun CORE_ADDR extract_typed_address (void *@var{buf}, struct type *@var{type}) | |
2397 | Treat the bytes at @var{buf} as a pointer or reference of type | |
2398 | @var{type}, and return the address it represents, in a manner | |
2399 | appropriate for the current architecture. This yields an address | |
2400 | @value{GDBN} can use to read target memory, disassemble, etc. Note that | |
2401 | @var{buf} refers to a buffer in @value{GDBN}'s memory, not the | |
2402 | inferior's. | |
2403 | ||
2404 | For example, if the current architecture is the Intel x86, this function | |
2405 | extracts a little-endian integer of the appropriate length from | |
2406 | @var{buf} and returns it. However, if the current architecture is the | |
2407 | D10V, this function will return a 16-bit integer extracted from | |
2408 | @var{buf}, multiplied by four if @var{type} is a pointer to a function. | |
2409 | ||
2410 | If @var{type} is not a pointer or reference type, then this function | |
2411 | will signal an internal error. | |
2412 | @end deftypefun | |
2413 | ||
2414 | @deftypefun CORE_ADDR store_typed_address (void *@var{buf}, struct type *@var{type}, CORE_ADDR @var{addr}) | |
2415 | Store the address @var{addr} in @var{buf}, in the proper format for a | |
2416 | pointer of type @var{type} in the current architecture. Note that | |
2417 | @var{buf} refers to a buffer in @value{GDBN}'s memory, not the | |
2418 | inferior's. | |
2419 | ||
2420 | For example, if the current architecture is the Intel x86, this function | |
2421 | stores @var{addr} unmodified as a little-endian integer of the | |
2422 | appropriate length in @var{buf}. However, if the current architecture | |
2423 | is the D10V, this function divides @var{addr} by four if @var{type} is | |
2424 | a pointer to a function, and then stores it in @var{buf}. | |
2425 | ||
2426 | If @var{type} is not a pointer or reference type, then this function | |
2427 | will signal an internal error. | |
2428 | @end deftypefun | |
2429 | ||
1aa20aa8 | 2430 | @deftypefun CORE_ADDR value_as_address (value_ptr @var{val}) |
93e79dbd JB |
2431 | Assuming that @var{val} is a pointer, return the address it represents, |
2432 | as appropriate for the current architecture. | |
2433 | ||
2434 | This function actually works on integral values, as well as pointers. | |
2435 | For pointers, it performs architecture-specific conversions as | |
2436 | described above for @code{extract_typed_address}. | |
2437 | @end deftypefun | |
2438 | ||
2439 | @deftypefun CORE_ADDR value_from_pointer (struct type *@var{type}, CORE_ADDR @var{addr}) | |
2440 | Create and return a value representing a pointer of type @var{type} to | |
2441 | the address @var{addr}, as appropriate for the current architecture. | |
2442 | This function performs architecture-specific conversions as described | |
2443 | above for @code{store_typed_address}. | |
2444 | @end deftypefun | |
2445 | ||
2446 | ||
2447 | @value{GDBN} also provides functions that do the same tasks, but assume | |
2448 | that pointers are simply byte addresses; they aren't sensitive to the | |
2449 | current architecture, beyond knowing the appropriate endianness. | |
2450 | ||
2451 | @deftypefun CORE_ADDR extract_address (void *@var{addr}, int len) | |
2452 | Extract a @var{len}-byte number from @var{addr} in the appropriate | |
2453 | endianness for the current architecture, and return it. Note that | |
2454 | @var{addr} refers to @value{GDBN}'s memory, not the inferior's. | |
2455 | ||
2456 | This function should only be used in architecture-specific code; it | |
2457 | doesn't have enough information to turn bits into a true address in the | |
2458 | appropriate way for the current architecture. If you can, use | |
2459 | @code{extract_typed_address} instead. | |
2460 | @end deftypefun | |
2461 | ||
2462 | @deftypefun void store_address (void *@var{addr}, int @var{len}, LONGEST @var{val}) | |
2463 | Store @var{val} at @var{addr} as a @var{len}-byte integer, in the | |
2464 | appropriate endianness for the current architecture. Note that | |
2465 | @var{addr} refers to a buffer in @value{GDBN}'s memory, not the | |
2466 | inferior's. | |
2467 | ||
2468 | This function should only be used in architecture-specific code; it | |
2469 | doesn't have enough information to turn a true address into bits in the | |
2470 | appropriate way for the current architecture. If you can, use | |
2471 | @code{store_typed_address} instead. | |
2472 | @end deftypefun | |
2473 | ||
2474 | ||
2475 | Here are some macros which architectures can define to indicate the | |
2476 | relationship between pointers and addresses. These have default | |
2477 | definitions, appropriate for architectures on which all pointers are | |
fc0c74b1 | 2478 | simple unsigned byte addresses. |
93e79dbd JB |
2479 | |
2480 | @deftypefn {Target Macro} CORE_ADDR POINTER_TO_ADDRESS (struct type *@var{type}, char *@var{buf}) | |
2481 | Assume that @var{buf} holds a pointer of type @var{type}, in the | |
2482 | appropriate format for the current architecture. Return the byte | |
2483 | address the pointer refers to. | |
2484 | ||
2485 | This function may safely assume that @var{type} is either a pointer or a | |
56caf160 | 2486 | C@t{++} reference type. |
93e79dbd JB |
2487 | @end deftypefn |
2488 | ||
2489 | @deftypefn {Target Macro} void ADDRESS_TO_POINTER (struct type *@var{type}, char *@var{buf}, CORE_ADDR @var{addr}) | |
2490 | Store in @var{buf} a pointer of type @var{type} representing the address | |
2491 | @var{addr}, in the appropriate format for the current architecture. | |
2492 | ||
2493 | This function may safely assume that @var{type} is either a pointer or a | |
56caf160 | 2494 | C@t{++} reference type. |
93e79dbd JB |
2495 | @end deftypefn |
2496 | ||
2497 | ||
9fb4dd36 JB |
2498 | @section Using Different Register and Memory Data Representations |
2499 | @cindex raw representation | |
2500 | @cindex virtual representation | |
2501 | @cindex representations, raw and virtual | |
2502 | @cindex register data formats, converting | |
2503 | @cindex @code{struct value}, converting register contents to | |
2504 | ||
af6c57ea AC |
2505 | @emph{Maintainer's note: The way GDB manipulates registers is undergoing |
2506 | significant change. Many of the macros and functions refered to in the | |
2507 | sections below are likely to be made obsolete. See the file @file{TODO} | |
2508 | for more up-to-date information.} | |
2509 | ||
9fb4dd36 JB |
2510 | Some architectures use one representation for a value when it lives in a |
2511 | register, but use a different representation when it lives in memory. | |
25822942 | 2512 | In @value{GDBN}'s terminology, the @dfn{raw} representation is the one used in |
9fb4dd36 | 2513 | the target registers, and the @dfn{virtual} representation is the one |
25822942 | 2514 | used in memory, and within @value{GDBN} @code{struct value} objects. |
9fb4dd36 JB |
2515 | |
2516 | For almost all data types on almost all architectures, the virtual and | |
2517 | raw representations are identical, and no special handling is needed. | |
2518 | However, they do occasionally differ. For example: | |
2519 | ||
2520 | @itemize @bullet | |
9fb4dd36 | 2521 | @item |
56caf160 | 2522 | The x86 architecture supports an 80-bit @code{long double} type. However, when |
9fb4dd36 JB |
2523 | we store those values in memory, they occupy twelve bytes: the |
2524 | floating-point number occupies the first ten, and the final two bytes | |
2525 | are unused. This keeps the values aligned on four-byte boundaries, | |
2526 | allowing more efficient access. Thus, the x86 80-bit floating-point | |
2527 | type is the raw representation, and the twelve-byte loosely-packed | |
2528 | arrangement is the virtual representation. | |
2529 | ||
2530 | @item | |
25822942 DB |
2531 | Some 64-bit MIPS targets present 32-bit registers to @value{GDBN} as 64-bit |
2532 | registers, with garbage in their upper bits. @value{GDBN} ignores the top 32 | |
9fb4dd36 JB |
2533 | bits. Thus, the 64-bit form, with garbage in the upper 32 bits, is the |
2534 | raw representation, and the trimmed 32-bit representation is the | |
2535 | virtual representation. | |
9fb4dd36 JB |
2536 | @end itemize |
2537 | ||
2538 | In general, the raw representation is determined by the architecture, or | |
25822942 DB |
2539 | @value{GDBN}'s interface to the architecture, while the virtual representation |
2540 | can be chosen for @value{GDBN}'s convenience. @value{GDBN}'s register file, | |
56caf160 EZ |
2541 | @code{registers}, holds the register contents in raw format, and the |
2542 | @value{GDBN} remote protocol transmits register values in raw format. | |
9fb4dd36 | 2543 | |
56caf160 EZ |
2544 | Your architecture may define the following macros to request |
2545 | conversions between the raw and virtual format: | |
9fb4dd36 JB |
2546 | |
2547 | @deftypefn {Target Macro} int REGISTER_CONVERTIBLE (int @var{reg}) | |
2548 | Return non-zero if register number @var{reg}'s value needs different raw | |
2549 | and virtual formats. | |
6f6ef15a EZ |
2550 | |
2551 | You should not use @code{REGISTER_CONVERT_TO_VIRTUAL} for a register | |
2552 | unless this macro returns a non-zero value for that register. | |
9fb4dd36 JB |
2553 | @end deftypefn |
2554 | ||
2555 | @deftypefn {Target Macro} int REGISTER_RAW_SIZE (int @var{reg}) | |
2556 | The size of register number @var{reg}'s raw value. This is the number | |
25822942 | 2557 | of bytes the register will occupy in @code{registers}, or in a @value{GDBN} |
9fb4dd36 JB |
2558 | remote protocol packet. |
2559 | @end deftypefn | |
2560 | ||
2561 | @deftypefn {Target Macro} int REGISTER_VIRTUAL_SIZE (int @var{reg}) | |
2562 | The size of register number @var{reg}'s value, in its virtual format. | |
2563 | This is the size a @code{struct value}'s buffer will have, holding that | |
2564 | register's value. | |
2565 | @end deftypefn | |
2566 | ||
2567 | @deftypefn {Target Macro} struct type *REGISTER_VIRTUAL_TYPE (int @var{reg}) | |
2568 | This is the type of the virtual representation of register number | |
2569 | @var{reg}. Note that there is no need for a macro giving a type for the | |
25822942 | 2570 | register's raw form; once the register's value has been obtained, @value{GDBN} |
9fb4dd36 JB |
2571 | always uses the virtual form. |
2572 | @end deftypefn | |
2573 | ||
2574 | @deftypefn {Target Macro} void REGISTER_CONVERT_TO_VIRTUAL (int @var{reg}, struct type *@var{type}, char *@var{from}, char *@var{to}) | |
2575 | Convert the value of register number @var{reg} to @var{type}, which | |
2576 | should always be @code{REGISTER_VIRTUAL_TYPE (@var{reg})}. The buffer | |
2577 | at @var{from} holds the register's value in raw format; the macro should | |
2578 | convert the value to virtual format, and place it at @var{to}. | |
2579 | ||
6f6ef15a EZ |
2580 | Note that @code{REGISTER_CONVERT_TO_VIRTUAL} and |
2581 | @code{REGISTER_CONVERT_TO_RAW} take their @var{reg} and @var{type} | |
2582 | arguments in different orders. | |
2583 | ||
2584 | You should only use @code{REGISTER_CONVERT_TO_VIRTUAL} with registers | |
2585 | for which the @code{REGISTER_CONVERTIBLE} macro returns a non-zero | |
2586 | value. | |
9fb4dd36 JB |
2587 | @end deftypefn |
2588 | ||
2589 | @deftypefn {Target Macro} void REGISTER_CONVERT_TO_RAW (struct type *@var{type}, int @var{reg}, char *@var{from}, char *@var{to}) | |
2590 | Convert the value of register number @var{reg} to @var{type}, which | |
2591 | should always be @code{REGISTER_VIRTUAL_TYPE (@var{reg})}. The buffer | |
2592 | at @var{from} holds the register's value in raw format; the macro should | |
2593 | convert the value to virtual format, and place it at @var{to}. | |
2594 | ||
2595 | Note that REGISTER_CONVERT_TO_VIRTUAL and REGISTER_CONVERT_TO_RAW take | |
2596 | their @var{reg} and @var{type} arguments in different orders. | |
2597 | @end deftypefn | |
2598 | ||
2599 | ||
c906108c SS |
2600 | @section Frame Interpretation |
2601 | ||
2602 | @section Inferior Call Setup | |
2603 | ||
2604 | @section Compiler Characteristics | |
2605 | ||
2606 | @section Target Conditionals | |
2607 | ||
2608 | This section describes the macros that you can use to define the target | |
2609 | machine. | |
2610 | ||
2611 | @table @code | |
2612 | ||
2613 | @item ADDITIONAL_OPTIONS | |
56caf160 EZ |
2614 | @itemx ADDITIONAL_OPTION_CASES |
2615 | @itemx ADDITIONAL_OPTION_HANDLER | |
2616 | @itemx ADDITIONAL_OPTION_HELP | |
2617 | @findex ADDITIONAL_OPTION_HELP | |
2618 | @findex ADDITIONAL_OPTION_HANDLER | |
2619 | @findex ADDITIONAL_OPTION_CASES | |
2620 | @findex ADDITIONAL_OPTIONS | |
c906108c | 2621 | These are a set of macros that allow the addition of additional command |
25822942 | 2622 | line options to @value{GDBN}. They are currently used only for the unsupported |
c906108c SS |
2623 | i960 Nindy target, and should not be used in any other configuration. |
2624 | ||
2625 | @item ADDR_BITS_REMOVE (addr) | |
56caf160 | 2626 | @findex ADDR_BITS_REMOVE |
adf40b2e JM |
2627 | If a raw machine instruction address includes any bits that are not |
2628 | really part of the address, then define this macro to expand into an | |
56caf160 | 2629 | expression that zeroes those bits in @var{addr}. This is only used for |
adf40b2e JM |
2630 | addresses of instructions, and even then not in all contexts. |
2631 | ||
2632 | For example, the two low-order bits of the PC on the Hewlett-Packard PA | |
2633 | 2.0 architecture contain the privilege level of the corresponding | |
2634 | instruction. Since instructions must always be aligned on four-byte | |
2635 | boundaries, the processor masks out these bits to generate the actual | |
2636 | address of the instruction. ADDR_BITS_REMOVE should filter out these | |
2637 | bits with an expression such as @code{((addr) & ~3)}. | |
c906108c | 2638 | |
93e79dbd | 2639 | @item ADDRESS_TO_POINTER (@var{type}, @var{buf}, @var{addr}) |
56caf160 | 2640 | @findex ADDRESS_TO_POINTER |
93e79dbd JB |
2641 | Store in @var{buf} a pointer of type @var{type} representing the address |
2642 | @var{addr}, in the appropriate format for the current architecture. | |
2643 | This macro may safely assume that @var{type} is either a pointer or a | |
56caf160 | 2644 | C@t{++} reference type. |
93e79dbd JB |
2645 | @xref{Target Architecture Definition, , Pointers Are Not Always Addresses}. |
2646 | ||
c906108c | 2647 | @item BEFORE_MAIN_LOOP_HOOK |
56caf160 | 2648 | @findex BEFORE_MAIN_LOOP_HOOK |
c906108c SS |
2649 | Define this to expand into any code that you want to execute before the |
2650 | main loop starts. Although this is not, strictly speaking, a target | |
2651 | conditional, that is how it is currently being used. Note that if a | |
2652 | configuration were to define it one way for a host and a different way | |
56caf160 EZ |
2653 | for the target, @value{GDBN} will probably not compile, let alone run |
2654 | correctly. This macro is currently used only for the unsupported i960 Nindy | |
2655 | target, and should not be used in any other configuration. | |
c906108c SS |
2656 | |
2657 | @item BELIEVE_PCC_PROMOTION | |
56caf160 EZ |
2658 | @findex BELIEVE_PCC_PROMOTION |
2659 | Define if the compiler promotes a @code{short} or @code{char} | |
2660 | parameter to an @code{int}, but still reports the parameter as its | |
2661 | original type, rather than the promoted type. | |
c906108c SS |
2662 | |
2663 | @item BELIEVE_PCC_PROMOTION_TYPE | |
56caf160 EZ |
2664 | @findex BELIEVE_PCC_PROMOTION_TYPE |
2665 | Define this if @value{GDBN} should believe the type of a @code{short} | |
2666 | argument when compiled by @code{pcc}, but look within a full int space to get | |
2667 | its value. Only defined for Sun-3 at present. | |
c906108c SS |
2668 | |
2669 | @item BITS_BIG_ENDIAN | |
56caf160 EZ |
2670 | @findex BITS_BIG_ENDIAN |
2671 | Define this if the numbering of bits in the targets does @strong{not} match the | |
c906108c | 2672 | endianness of the target byte order. A value of 1 means that the bits |
56caf160 | 2673 | are numbered in a big-endian bit order, 0 means little-endian. |
c906108c SS |
2674 | |
2675 | @item BREAKPOINT | |
56caf160 | 2676 | @findex BREAKPOINT |
c906108c SS |
2677 | This is the character array initializer for the bit pattern to put into |
2678 | memory where a breakpoint is set. Although it's common to use a trap | |
2679 | instruction for a breakpoint, it's not required; for instance, the bit | |
2680 | pattern could be an invalid instruction. The breakpoint must be no | |
2681 | longer than the shortest instruction of the architecture. | |
2682 | ||
56caf160 EZ |
2683 | @code{BREAKPOINT} has been deprecated in favor of |
2684 | @code{BREAKPOINT_FROM_PC}. | |
7a292a7a | 2685 | |
c906108c | 2686 | @item BIG_BREAKPOINT |
56caf160 EZ |
2687 | @itemx LITTLE_BREAKPOINT |
2688 | @findex LITTLE_BREAKPOINT | |
2689 | @findex BIG_BREAKPOINT | |
c906108c SS |
2690 | Similar to BREAKPOINT, but used for bi-endian targets. |
2691 | ||
56caf160 EZ |
2692 | @code{BIG_BREAKPOINT} and @code{LITTLE_BREAKPOINT} have been deprecated in |
2693 | favor of @code{BREAKPOINT_FROM_PC}. | |
7a292a7a | 2694 | |
c906108c | 2695 | @item REMOTE_BREAKPOINT |
56caf160 EZ |
2696 | @itemx LITTLE_REMOTE_BREAKPOINT |
2697 | @itemx BIG_REMOTE_BREAKPOINT | |
2698 | @findex BIG_REMOTE_BREAKPOINT | |
2699 | @findex LITTLE_REMOTE_BREAKPOINT | |
2700 | @findex REMOTE_BREAKPOINT | |
c906108c SS |
2701 | Similar to BREAKPOINT, but used for remote targets. |
2702 | ||
56caf160 EZ |
2703 | @code{BIG_REMOTE_BREAKPOINT} and @code{LITTLE_REMOTE_BREAKPOINT} have been |
2704 | deprecated in favor of @code{BREAKPOINT_FROM_PC}. | |
c906108c | 2705 | |
56caf160 EZ |
2706 | @item BREAKPOINT_FROM_PC (@var{pcptr}, @var{lenptr}) |
2707 | @findex BREAKPOINT_FROM_PC | |
c906108c | 2708 | Use the program counter to determine the contents and size of a |
56caf160 EZ |
2709 | breakpoint instruction. It returns a pointer to a string of bytes |
2710 | that encode a breakpoint instruction, stores the length of the string | |
2711 | to *@var{lenptr}, and adjusts pc (if necessary) to point to the actual | |
2712 | memory location where the breakpoint should be inserted. | |
c906108c SS |
2713 | |
2714 | Although it is common to use a trap instruction for a breakpoint, it's | |
2715 | not required; for instance, the bit pattern could be an invalid | |
2716 | instruction. The breakpoint must be no longer than the shortest | |
2717 | instruction of the architecture. | |
2718 | ||
7a292a7a SS |
2719 | Replaces all the other @var{BREAKPOINT} macros. |
2720 | ||
56caf160 EZ |
2721 | @item MEMORY_INSERT_BREAKPOINT (@var{addr}, @var{contents_cache}) |
2722 | @itemx MEMORY_REMOVE_BREAKPOINT (@var{addr}, @var{contents_cache}) | |
2723 | @findex MEMORY_REMOVE_BREAKPOINT | |
2724 | @findex MEMORY_INSERT_BREAKPOINT | |
917317f4 JM |
2725 | Insert or remove memory based breakpoints. Reasonable defaults |
2726 | (@code{default_memory_insert_breakpoint} and | |
2727 | @code{default_memory_remove_breakpoint} respectively) have been | |
2728 | provided so that it is not necessary to define these for most | |
2729 | architectures. Architectures which may want to define | |
56caf160 | 2730 | @code{MEMORY_INSERT_BREAKPOINT} and @code{MEMORY_REMOVE_BREAKPOINT} will |
917317f4 JM |
2731 | likely have instructions that are oddly sized or are not stored in a |
2732 | conventional manner. | |
2733 | ||
2734 | It may also be desirable (from an efficiency standpoint) to define | |
2735 | custom breakpoint insertion and removal routines if | |
56caf160 | 2736 | @code{BREAKPOINT_FROM_PC} needs to read the target's memory for some |
917317f4 JM |
2737 | reason. |
2738 | ||
7a292a7a | 2739 | @item CALL_DUMMY_P |
56caf160 | 2740 | @findex CALL_DUMMY_P |
7a292a7a SS |
2741 | A C expresson that is non-zero when the target suports inferior function |
2742 | calls. | |
2743 | ||
2744 | @item CALL_DUMMY_WORDS | |
56caf160 EZ |
2745 | @findex CALL_DUMMY_WORDS |
2746 | Pointer to an array of @code{LONGEST} words of data containing | |
2747 | host-byte-ordered @code{REGISTER_BYTES} sized values that partially | |
7a292a7a SS |
2748 | specify the sequence of instructions needed for an inferior function |
2749 | call. | |
2750 | ||
56caf160 | 2751 | Should be deprecated in favor of a macro that uses target-byte-ordered |
7a292a7a SS |
2752 | data. |
2753 | ||
2754 | @item SIZEOF_CALL_DUMMY_WORDS | |
56caf160 EZ |
2755 | @findex SIZEOF_CALL_DUMMY_WORDS |
2756 | The size of @code{CALL_DUMMY_WORDS}. When @code{CALL_DUMMY_P} this must | |
2757 | return a positive value. See also @code{CALL_DUMMY_LENGTH}. | |
c906108c SS |
2758 | |
2759 | @item CALL_DUMMY | |
56caf160 EZ |
2760 | @findex CALL_DUMMY |
2761 | A static initializer for @code{CALL_DUMMY_WORDS}. Deprecated. | |
7a292a7a | 2762 | |
c906108c | 2763 | @item CALL_DUMMY_LOCATION |
56caf160 EZ |
2764 | @findex CALL_DUMMY_LOCATION |
2765 | See the file @file{inferior.h}. | |
7a292a7a | 2766 | |
c906108c | 2767 | @item CALL_DUMMY_STACK_ADJUST |
56caf160 | 2768 | @findex CALL_DUMMY_STACK_ADJUST |
7a292a7a SS |
2769 | Stack adjustment needed when performing an inferior function call. |
2770 | ||
56caf160 | 2771 | Should be deprecated in favor of something like @code{STACK_ALIGN}. |
7a292a7a SS |
2772 | |
2773 | @item CALL_DUMMY_STACK_ADJUST_P | |
56caf160 EZ |
2774 | @findex CALL_DUMMY_STACK_ADJUST_P |
2775 | Predicate for use of @code{CALL_DUMMY_STACK_ADJUST}. | |
7a292a7a | 2776 | |
56caf160 | 2777 | Should be deprecated in favor of something like @code{STACK_ALIGN}. |
c906108c | 2778 | |
56caf160 EZ |
2779 | @item CANNOT_FETCH_REGISTER (@var{regno}) |
2780 | @findex CANNOT_FETCH_REGISTER | |
c906108c SS |
2781 | A C expression that should be nonzero if @var{regno} cannot be fetched |
2782 | from an inferior process. This is only relevant if | |
2783 | @code{FETCH_INFERIOR_REGISTERS} is not defined. | |
2784 | ||
56caf160 EZ |
2785 | @item CANNOT_STORE_REGISTER (@var{regno}) |
2786 | @findex CANNOT_STORE_REGISTER | |
c906108c SS |
2787 | A C expression that should be nonzero if @var{regno} should not be |
2788 | written to the target. This is often the case for program counters, | |
56caf160 EZ |
2789 | status words, and other special registers. If this is not defined, |
2790 | @value{GDBN} will assume that all registers may be written. | |
c906108c SS |
2791 | |
2792 | @item DO_DEFERRED_STORES | |
a5d7c491 | 2793 | @itemx CLEAR_DEFERRED_STORES |
56caf160 EZ |
2794 | @findex CLEAR_DEFERRED_STORES |
2795 | @findex DO_DEFERRED_STORES | |
c906108c SS |
2796 | Define this to execute any deferred stores of registers into the inferior, |
2797 | and to cancel any deferred stores. | |
2798 | ||
2799 | Currently only implemented correctly for native Sparc configurations? | |
2800 | ||
ef36d45e | 2801 | @item COERCE_FLOAT_TO_DOUBLE (@var{formal}, @var{actual}) |
56caf160 EZ |
2802 | @findex COERCE_FLOAT_TO_DOUBLE |
2803 | @cindex promotion to @code{double} | |
3fe0dc10 JB |
2804 | @cindex @code{float} arguments |
2805 | @cindex prototyped functions, passing arguments to | |
2806 | @cindex passing arguments to prototyped functions | |
2807 | Return non-zero if GDB should promote @code{float} values to | |
2808 | @code{double} when calling a non-prototyped function. The argument | |
2809 | @var{actual} is the type of the value we want to pass to the function. | |
2810 | The argument @var{formal} is the type of this argument, as it appears in | |
2811 | the function's definition. Note that @var{formal} may be zero if we | |
2812 | have no debugging information for the function, or if we're passing more | |
2813 | arguments than are officially declared (for example, varargs). This | |
2814 | macro is never invoked if the function definitely has a prototype. | |
2815 | ||
2816 | How you should pass arguments to a function depends on whether it was | |
2817 | defined in K&R style or prototype style. If you define a function using | |
2818 | the K&R syntax that takes a @code{float} argument, then callers must | |
2819 | pass that argument as a @code{double}. If you define the function using | |
2820 | the prototype syntax, then you must pass the argument as a @code{float}, | |
2821 | with no promotion. | |
2822 | ||
2823 | Unfortunately, on certain older platforms, the debug info doesn't | |
2824 | indicate reliably how each function was defined. A function type's | |
2825 | @code{TYPE_FLAG_PROTOTYPED} flag may be unset, even if the function was | |
2826 | defined in prototype style. When calling a function whose | |
2827 | @code{TYPE_FLAG_PROTOTYPED} flag is unset, GDB consults the | |
2828 | @code{COERCE_FLOAT_TO_DOUBLE} macro to decide what to do. | |
2829 | ||
56caf160 | 2830 | @findex standard_coerce_float_to_double |
3fe0dc10 JB |
2831 | For modern targets, it is proper to assume that, if the prototype flag |
2832 | is unset, that can be trusted: @code{float} arguments should be promoted | |
2833 | to @code{double}. You should use the function | |
2834 | @code{standard_coerce_float_to_double} to get this behavior. | |
2835 | ||
2836 | @findex default_coerce_float_to_double | |
2837 | For some older targets, if the prototype flag is unset, that doesn't | |
2838 | tell us anything. So we guess that, if we don't have a type for the | |
2839 | formal parameter (@i{i.e.}, the first argument to | |
2840 | @code{COERCE_FLOAT_TO_DOUBLE} is null), then we should promote it; | |
2841 | otherwise, we should leave it alone. The function | |
2842 | @code{default_coerce_float_to_double} provides this behavior; it is the | |
2843 | default value, for compatibility with older configurations. | |
ef36d45e | 2844 | |
c906108c | 2845 | @item CPLUS_MARKER |
56caf160 EZ |
2846 | @findex CPLUS_MARKERz |
2847 | Define this to expand into the character that G@t{++} uses to distinguish | |
c906108c SS |
2848 | compiler-generated identifiers from programmer-specified identifiers. |
2849 | By default, this expands into @code{'$'}. Most System V targets should | |
2850 | define this to @code{'.'}. | |
2851 | ||
2852 | @item DBX_PARM_SYMBOL_CLASS | |
56caf160 | 2853 | @findex DBX_PARM_SYMBOL_CLASS |
c906108c SS |
2854 | Hook for the @code{SYMBOL_CLASS} of a parameter when decoding DBX symbol |
2855 | information. In the i960, parameters can be stored as locals or as | |
2856 | args, depending on the type of the debug record. | |
2857 | ||
2858 | @item DECR_PC_AFTER_BREAK | |
56caf160 | 2859 | @findex DECR_PC_AFTER_BREAK |
c906108c SS |
2860 | Define this to be the amount by which to decrement the PC after the |
2861 | program encounters a breakpoint. This is often the number of bytes in | |
56caf160 | 2862 | @code{BREAKPOINT}, though not always. For most targets this value will be 0. |
c906108c SS |
2863 | |
2864 | @item DECR_PC_AFTER_HW_BREAK | |
56caf160 | 2865 | @findex DECR_PC_AFTER_HW_BREAK |
c906108c SS |
2866 | Similarly, for hardware breakpoints. |
2867 | ||
56caf160 EZ |
2868 | @item DISABLE_UNSETTABLE_BREAK (@var{addr}) |
2869 | @findex DISABLE_UNSETTABLE_BREAK | |
c906108c SS |
2870 | If defined, this should evaluate to 1 if @var{addr} is in a shared |
2871 | library in which breakpoints cannot be set and so should be disabled. | |
2872 | ||
2873 | @item DO_REGISTERS_INFO | |
56caf160 | 2874 | @findex DO_REGISTERS_INFO |
c906108c SS |
2875 | If defined, use this to print the value of a register or all registers. |
2876 | ||
0dcedd82 | 2877 | @item DWARF_REG_TO_REGNUM |
56caf160 | 2878 | @findex DWARF_REG_TO_REGNUM |
0dcedd82 AC |
2879 | Convert DWARF register number into @value{GDBN} regnum. If not defined, |
2880 | no conversion will be performed. | |
2881 | ||
2882 | @item DWARF2_REG_TO_REGNUM | |
56caf160 | 2883 | @findex DWARF2_REG_TO_REGNUM |
0dcedd82 AC |
2884 | Convert DWARF2 register number into @value{GDBN} regnum. If not |
2885 | defined, no conversion will be performed. | |
2886 | ||
2887 | @item ECOFF_REG_TO_REGNUM | |
56caf160 | 2888 | @findex ECOFF_REG_TO_REGNUM |
0dcedd82 AC |
2889 | Convert ECOFF register number into @value{GDBN} regnum. If not defined, |
2890 | no conversion will be performed. | |
2891 | ||
c906108c | 2892 | @item END_OF_TEXT_DEFAULT |
56caf160 EZ |
2893 | @findex END_OF_TEXT_DEFAULT |
2894 | This is an expression that should designate the end of the text section. | |
2895 | @c (? FIXME ?) | |
c906108c | 2896 | |
56caf160 EZ |
2897 | @item EXTRACT_RETURN_VALUE(@var{type}, @var{regbuf}, @var{valbuf}) |
2898 | @findex EXTRACT_RETURN_VALUE | |
c906108c SS |
2899 | Define this to extract a function's return value of type @var{type} from |
2900 | the raw register state @var{regbuf} and copy that, in virtual format, | |
2901 | into @var{valbuf}. | |
2902 | ||
56caf160 EZ |
2903 | @item EXTRACT_STRUCT_VALUE_ADDRESS(@var{regbuf}) |
2904 | @findex EXTRACT_STRUCT_VALUE_ADDRESS | |
83aa8bc6 AC |
2905 | When defined, extract from the array @var{regbuf} (containing the raw |
2906 | register state) the @code{CORE_ADDR} at which a function should return | |
2907 | its structure value. | |
ac9a91a7 | 2908 | |
83aa8bc6 AC |
2909 | If not defined, @code{EXTRACT_RETURN_VALUE} is used. |
2910 | ||
2911 | @item EXTRACT_STRUCT_VALUE_ADDRESS_P() | |
56caf160 EZ |
2912 | @findex EXTRACT_STRUCT_VALUE_ADDRESS_P |
2913 | Predicate for @code{EXTRACT_STRUCT_VALUE_ADDRESS}. | |
c906108c SS |
2914 | |
2915 | @item FLOAT_INFO | |
56caf160 EZ |
2916 | @findex FLOAT_INFO |
2917 | If defined, then the @samp{info float} command will print information about | |
c906108c SS |
2918 | the processor's floating point unit. |
2919 | ||
2920 | @item FP_REGNUM | |
56caf160 | 2921 | @findex FP_REGNUM |
cce74817 JM |
2922 | If the virtual frame pointer is kept in a register, then define this |
2923 | macro to be the number (greater than or equal to zero) of that register. | |
2924 | ||
2925 | This should only need to be defined if @code{TARGET_READ_FP} and | |
2926 | @code{TARGET_WRITE_FP} are not defined. | |
c906108c | 2927 | |
56caf160 EZ |
2928 | @item FRAMELESS_FUNCTION_INVOCATION(@var{fi}) |
2929 | @findex FRAMELESS_FUNCTION_INVOCATION | |
392a587b JM |
2930 | Define this to an expression that returns 1 if the function invocation |
2931 | represented by @var{fi} does not have a stack frame associated with it. | |
2932 | Otherwise return 0. | |
c906108c | 2933 | |
a5d7c491 | 2934 | @item FRAME_ARGS_ADDRESS_CORRECT |
56caf160 EZ |
2935 | @findex FRAME_ARGS_ADDRESS_CORRECT |
2936 | See @file{stack.c}. | |
c906108c | 2937 | |
56caf160 EZ |
2938 | @item FRAME_CHAIN(@var{frame}) |
2939 | @findex FRAME_CHAIN | |
c906108c SS |
2940 | Given @var{frame}, return a pointer to the calling frame. |
2941 | ||
56caf160 EZ |
2942 | @item FRAME_CHAIN_COMBINE(@var{chain}, @var{frame}) |
2943 | @findex FRAME_CHAIN_COMBINE | |
c906108c SS |
2944 | Define this to take the frame chain pointer and the frame's nominal |
2945 | address and produce the nominal address of the caller's frame. | |
2946 | Presently only defined for HP PA. | |
2947 | ||
56caf160 EZ |
2948 | @item FRAME_CHAIN_VALID(@var{chain}, @var{thisframe}) |
2949 | @findex FRAME_CHAIN_VALID | |
c906108c | 2950 | Define this to be an expression that returns zero if the given frame is |
c4093a6a | 2951 | an outermost frame, with no caller, and nonzero otherwise. Several |
56caf160 | 2952 | common definitions are available: |
c4093a6a | 2953 | |
56caf160 EZ |
2954 | @itemize @bullet |
2955 | @item | |
c4093a6a JM |
2956 | @code{file_frame_chain_valid} is nonzero if the chain pointer is nonzero |
2957 | and given frame's PC is not inside the startup file (such as | |
56caf160 EZ |
2958 | @file{crt0.o}). |
2959 | ||
2960 | @item | |
2961 | @code{func_frame_chain_valid} is nonzero if the chain | |
2962 | pointer is nonzero and the given frame's PC is not in @code{main} or a | |
2963 | known entry point function (such as @code{_start}). | |
2964 | ||
2965 | @item | |
c4093a6a JM |
2966 | @code{generic_file_frame_chain_valid} and |
2967 | @code{generic_func_frame_chain_valid} are equivalent implementations for | |
2968 | targets using generic dummy frames. | |
56caf160 | 2969 | @end itemize |
c906108c | 2970 | |
56caf160 EZ |
2971 | @item FRAME_INIT_SAVED_REGS(@var{frame}) |
2972 | @findex FRAME_INIT_SAVED_REGS | |
c906108c SS |
2973 | See @file{frame.h}. Determines the address of all registers in the |
2974 | current stack frame storing each in @code{frame->saved_regs}. Space for | |
2975 | @code{frame->saved_regs} shall be allocated by | |
2976 | @code{FRAME_INIT_SAVED_REGS} using either | |
2977 | @code{frame_saved_regs_zalloc} or @code{frame_obstack_alloc}. | |
2978 | ||
56caf160 | 2979 | @code{FRAME_FIND_SAVED_REGS} and @code{EXTRA_FRAME_INFO} are deprecated. |
c906108c | 2980 | |
56caf160 EZ |
2981 | @item FRAME_NUM_ARGS (@var{fi}) |
2982 | @findex FRAME_NUM_ARGS | |
392a587b JM |
2983 | For the frame described by @var{fi} return the number of arguments that |
2984 | are being passed. If the number of arguments is not known, return | |
2985 | @code{-1}. | |
c906108c | 2986 | |
56caf160 EZ |
2987 | @item FRAME_SAVED_PC(@var{frame}) |
2988 | @findex FRAME_SAVED_PC | |
2989 | Given @var{frame}, return the pc saved there. This is the return | |
c906108c SS |
2990 | address. |
2991 | ||
2992 | @item FUNCTION_EPILOGUE_SIZE | |
56caf160 | 2993 | @findex FUNCTION_EPILOGUE_SIZE |
c906108c SS |
2994 | For some COFF targets, the @code{x_sym.x_misc.x_fsize} field of the |
2995 | function end symbol is 0. For such targets, you must define | |
2996 | @code{FUNCTION_EPILOGUE_SIZE} to expand into the standard size of a | |
2997 | function's epilogue. | |
2998 | ||
f7cb2b90 | 2999 | @item FUNCTION_START_OFFSET |
56caf160 | 3000 | @findex FUNCTION_START_OFFSET |
f7cb2b90 JB |
3001 | An integer, giving the offset in bytes from a function's address (as |
3002 | used in the values of symbols, function pointers, etc.), and the | |
3003 | function's first genuine instruction. | |
3004 | ||
3005 | This is zero on almost all machines: the function's address is usually | |
3006 | the address of its first instruction. However, on the VAX, for example, | |
3007 | each function starts with two bytes containing a bitmask indicating | |
3008 | which registers to save upon entry to the function. The VAX @code{call} | |
3009 | instructions check this value, and save the appropriate registers | |
3010 | automatically. Thus, since the offset from the function's address to | |
3011 | its first instruction is two bytes, @code{FUNCTION_START_OFFSET} would | |
3012 | be 2 on the VAX. | |
3013 | ||
c906108c | 3014 | @item GCC_COMPILED_FLAG_SYMBOL |
56caf160 EZ |
3015 | @itemx GCC2_COMPILED_FLAG_SYMBOL |
3016 | @findex GCC2_COMPILED_FLAG_SYMBOL | |
3017 | @findex GCC_COMPILED_FLAG_SYMBOL | |
3018 | If defined, these are the names of the symbols that @value{GDBN} will | |
3019 | look for to detect that GCC compiled the file. The default symbols | |
3020 | are @code{gcc_compiled.} and @code{gcc2_compiled.}, | |
3021 | respectively. (Currently only defined for the Delta 68.) | |
c906108c | 3022 | |
25822942 | 3023 | @item @value{GDBN}_MULTI_ARCH |
56caf160 | 3024 | @findex @value{GDBN}_MULTI_ARCH |
0f71a2f6 | 3025 | If defined and non-zero, enables suport for multiple architectures |
25822942 | 3026 | within @value{GDBN}. |
0f71a2f6 | 3027 | |
56caf160 | 3028 | This support can be enabled at two levels. At level one, only |
0f71a2f6 JM |
3029 | definitions for previously undefined macros are provided; at level two, |
3030 | a multi-arch definition of all architecture dependant macros will be | |
3031 | defined. | |
3032 | ||
25822942 | 3033 | @item @value{GDBN}_TARGET_IS_HPPA |
56caf160 EZ |
3034 | @findex @value{GDBN}_TARGET_IS_HPPA |
3035 | This determines whether horrible kludge code in @file{dbxread.c} and | |
3036 | @file{partial-stab.h} is used to mangle multiple-symbol-table files from | |
3037 | HPPA's. This should all be ripped out, and a scheme like @file{elfread.c} | |
3038 | used instead. | |
c906108c | 3039 | |
c906108c | 3040 | @item GET_LONGJMP_TARGET |
56caf160 | 3041 | @findex GET_LONGJMP_TARGET |
c906108c SS |
3042 | For most machines, this is a target-dependent parameter. On the |
3043 | DECstation and the Iris, this is a native-dependent parameter, since | |
56caf160 | 3044 | trhe header file @file{setjmp.h} is needed to define it. |
c906108c | 3045 | |
56caf160 EZ |
3046 | This macro determines the target PC address that @code{longjmp} will jump to, |
3047 | assuming that we have just stopped at a @code{longjmp} breakpoint. It takes a | |
3048 | @code{CORE_ADDR *} as argument, and stores the target PC value through this | |
c906108c SS |
3049 | pointer. It examines the current state of the machine as needed. |
3050 | ||
3051 | @item GET_SAVED_REGISTER | |
56caf160 EZ |
3052 | @findex GET_SAVED_REGISTER |
3053 | @findex get_saved_register | |
c906108c | 3054 | Define this if you need to supply your own definition for the function |
7a292a7a | 3055 | @code{get_saved_register}. |
c906108c SS |
3056 | |
3057 | @item HAVE_REGISTER_WINDOWS | |
56caf160 | 3058 | @findex HAVE_REGISTER_WINDOWS |
c906108c | 3059 | Define this if the target has register windows. |
56caf160 EZ |
3060 | |
3061 | @item REGISTER_IN_WINDOW_P (@var{regnum}) | |
3062 | @findex REGISTER_IN_WINDOW_P | |
c906108c SS |
3063 | Define this to be an expression that is 1 if the given register is in |
3064 | the window. | |
3065 | ||
3066 | @item IBM6000_TARGET | |
56caf160 | 3067 | @findex IBM6000_TARGET |
c906108c SS |
3068 | Shows that we are configured for an IBM RS/6000 target. This |
3069 | conditional should be eliminated (FIXME) and replaced by | |
56caf160 | 3070 | feature-specific macros. It was introduced in a haste and we are |
c906108c SS |
3071 | repenting at leisure. |
3072 | ||
9742079a EZ |
3073 | @item I386_USE_GENERIC_WATCHPOINTS |
3074 | An x86-based target can define this to use the generic x86 watchpoint | |
3075 | support; see @ref{Algorithms, I386_USE_GENERIC_WATCHPOINTS}. | |
3076 | ||
2df3850c | 3077 | @item SYMBOLS_CAN_START_WITH_DOLLAR |
56caf160 | 3078 | @findex SYMBOLS_CAN_START_WITH_DOLLAR |
2df3850c | 3079 | Some systems have routines whose names start with @samp{$}. Giving this |
25822942 | 3080 | macro a non-zero value tells @value{GDBN}'s expression parser to check for such |
2df3850c JM |
3081 | routines when parsing tokens that begin with @samp{$}. |
3082 | ||
3083 | On HP-UX, certain system routines (millicode) have names beginning with | |
3084 | @samp{$} or @samp{$$}. For example, @code{$$dyncall} is a millicode | |
3085 | routine that handles inter-space procedure calls on PA-RISC. | |
3086 | ||
c906108c | 3087 | @item IEEE_FLOAT |
56caf160 | 3088 | @findex IEEE_FLOAT |
c906108c SS |
3089 | Define this if the target system uses IEEE-format floating point numbers. |
3090 | ||
56caf160 EZ |
3091 | @item INIT_EXTRA_FRAME_INFO (@var{fromleaf}, @var{frame}) |
3092 | @findex INIT_EXTRA_FRAME_INFO | |
c906108c SS |
3093 | If additional information about the frame is required this should be |
3094 | stored in @code{frame->extra_info}. Space for @code{frame->extra_info} | |
3095 | is allocated using @code{frame_obstack_alloc}. | |
3096 | ||
56caf160 EZ |
3097 | @item INIT_FRAME_PC (@var{fromleaf}, @var{prev}) |
3098 | @findex INIT_FRAME_PC | |
c906108c SS |
3099 | This is a C statement that sets the pc of the frame pointed to by |
3100 | @var{prev}. [By default...] | |
3101 | ||
56caf160 EZ |
3102 | @item INNER_THAN (@var{lhs}, @var{rhs}) |
3103 | @findex INNER_THAN | |
c906108c SS |
3104 | Returns non-zero if stack address @var{lhs} is inner than (nearer to the |
3105 | stack top) stack address @var{rhs}. Define this as @code{lhs < rhs} if | |
3106 | the target's stack grows downward in memory, or @code{lhs > rsh} if the | |
3107 | stack grows upward. | |
3108 | ||
9e5abb06 CV |
3109 | @item gdbarch_in_function_epilogue_p (@var{gdbarch}, @var{pc}) |
3110 | @findex gdbarch_in_function_epilogue_p | |
3111 | Returns non-zero if the given @var{pc} is in the epilogue of a function. | |
3112 | The epilogue of a function is defined as the part of a function where | |
3113 | the stack frame of the function already has been destroyed up to the | |
3114 | final `return from function call' instruction. | |
3115 | ||
56caf160 EZ |
3116 | @item IN_SIGTRAMP (@var{pc}, @var{name}) |
3117 | @findex IN_SIGTRAMP | |
3118 | Define this to return non-zero if the given @var{pc} and/or @var{name} | |
3119 | indicates that the current function is a @code{sigtramp}. | |
c906108c | 3120 | |
56caf160 EZ |
3121 | @item SIGTRAMP_START (@var{pc}) |
3122 | @findex SIGTRAMP_START | |
3123 | @itemx SIGTRAMP_END (@var{pc}) | |
3124 | @findex SIGTRAMP_END | |
3125 | Define these to be the start and end address of the @code{sigtramp} for the | |
c906108c SS |
3126 | given @var{pc}. On machines where the address is just a compile time |
3127 | constant, the macro expansion will typically just ignore the supplied | |
3128 | @var{pc}. | |
3129 | ||
56caf160 EZ |
3130 | @item IN_SOLIB_CALL_TRAMPOLINE (@var{pc}, @var{name}) |
3131 | @findex IN_SOLIB_CALL_TRAMPOLINE | |
c906108c SS |
3132 | Define this to evaluate to nonzero if the program is stopped in the |
3133 | trampoline that connects to a shared library. | |
3134 | ||
56caf160 EZ |
3135 | @item IN_SOLIB_RETURN_TRAMPOLINE (@var{pc}, @var{name}) |
3136 | @findex IN_SOLIB_RETURN_TRAMPOLINE | |
c906108c SS |
3137 | Define this to evaluate to nonzero if the program is stopped in the |
3138 | trampoline that returns from a shared library. | |
3139 | ||
56caf160 EZ |
3140 | @item IN_SOLIB_DYNSYM_RESOLVE_CODE (@var{pc}) |
3141 | @findex IN_SOLIB_DYNSYM_RESOLVE_CODE | |
d4f3574e SS |
3142 | Define this to evaluate to nonzero if the program is stopped in the |
3143 | dynamic linker. | |
3144 | ||
56caf160 EZ |
3145 | @item SKIP_SOLIB_RESOLVER (@var{pc}) |
3146 | @findex SKIP_SOLIB_RESOLVER | |
d4f3574e SS |
3147 | Define this to evaluate to the (nonzero) address at which execution |
3148 | should continue to get past the dynamic linker's symbol resolution | |
3149 | function. A zero value indicates that it is not important or necessary | |
3150 | to set a breakpoint to get through the dynamic linker and that single | |
3151 | stepping will suffice. | |
3152 | ||
fc0c74b1 AC |
3153 | @item INTEGER_TO_ADDRESS (@var{type}, @var{buf}) |
3154 | @findex INTEGER_TO_ADDRESS | |
3155 | @cindex converting integers to addresses | |
3156 | Define this when the architecture needs to handle non-pointer to address | |
3157 | conversions specially. Converts that value to an address according to | |
3158 | the current architectures conventions. | |
3159 | ||
3160 | @emph{Pragmatics: When the user copies a well defined expression from | |
3161 | their source code and passes it, as a parameter, to @value{GDBN}'s | |
3162 | @code{print} command, they should get the same value as would have been | |
3163 | computed by the target program. Any deviation from this rule can cause | |
3164 | major confusion and annoyance, and needs to be justified carefully. In | |
3165 | other words, @value{GDBN} doesn't really have the freedom to do these | |
3166 | conversions in clever and useful ways. It has, however, been pointed | |
3167 | out that users aren't complaining about how @value{GDBN} casts integers | |
3168 | to pointers; they are complaining that they can't take an address from a | |
3169 | disassembly listing and give it to @code{x/i}. Adding an architecture | |
3170 | method like @code{INTEGER_TO_ADDRESS} certainly makes it possible for | |
3171 | @value{GDBN} to ``get it right'' in all circumstances.} | |
3172 | ||
3173 | @xref{Target Architecture Definition, , Pointers Are Not Always | |
3174 | Addresses}. | |
3175 | ||
56caf160 EZ |
3176 | @item IS_TRAPPED_INTERNALVAR (@var{name}) |
3177 | @findex IS_TRAPPED_INTERNALVAR | |
c906108c SS |
3178 | This is an ugly hook to allow the specification of special actions that |
3179 | should occur as a side-effect of setting the value of a variable | |
25822942 | 3180 | internal to @value{GDBN}. Currently only used by the h8500. Note that this |
c906108c SS |
3181 | could be either a host or target conditional. |
3182 | ||
3183 | @item NEED_TEXT_START_END | |
56caf160 | 3184 | @findex NEED_TEXT_START_END |
25822942 | 3185 | Define this if @value{GDBN} should determine the start and end addresses of the |
c906108c SS |
3186 | text section. (Seems dubious.) |
3187 | ||
3188 | @item NO_HIF_SUPPORT | |
56caf160 | 3189 | @findex NO_HIF_SUPPORT |
c906108c SS |
3190 | (Specific to the a29k.) |
3191 | ||
93e79dbd | 3192 | @item POINTER_TO_ADDRESS (@var{type}, @var{buf}) |
56caf160 | 3193 | @findex POINTER_TO_ADDRESS |
93e79dbd JB |
3194 | Assume that @var{buf} holds a pointer of type @var{type}, in the |
3195 | appropriate format for the current architecture. Return the byte | |
3196 | address the pointer refers to. | |
3197 | @xref{Target Architecture Definition, , Pointers Are Not Always Addresses}. | |
3198 | ||
9fb4dd36 | 3199 | @item REGISTER_CONVERTIBLE (@var{reg}) |
56caf160 | 3200 | @findex REGISTER_CONVERTIBLE |
9fb4dd36 | 3201 | Return non-zero if @var{reg} uses different raw and virtual formats. |
4281a42e | 3202 | @xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}. |
9fb4dd36 JB |
3203 | |
3204 | @item REGISTER_RAW_SIZE (@var{reg}) | |
56caf160 | 3205 | @findex REGISTER_RAW_SIZE |
9fb4dd36 | 3206 | Return the raw size of @var{reg}. |
4281a42e | 3207 | @xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}. |
9fb4dd36 JB |
3208 | |
3209 | @item REGISTER_VIRTUAL_SIZE (@var{reg}) | |
56caf160 | 3210 | @findex REGISTER_VIRTUAL_SIZE |
9fb4dd36 | 3211 | Return the virtual size of @var{reg}. |
4281a42e | 3212 | @xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}. |
9fb4dd36 JB |
3213 | |
3214 | @item REGISTER_VIRTUAL_TYPE (@var{reg}) | |
56caf160 | 3215 | @findex REGISTER_VIRTUAL_TYPE |
9fb4dd36 | 3216 | Return the virtual type of @var{reg}. |
4281a42e | 3217 | @xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}. |
9fb4dd36 JB |
3218 | |
3219 | @item REGISTER_CONVERT_TO_VIRTUAL(@var{reg}, @var{type}, @var{from}, @var{to}) | |
56caf160 | 3220 | @findex REGISTER_CONVERT_TO_VIRTUAL |
9fb4dd36 | 3221 | Convert the value of register @var{reg} from its raw form to its virtual |
4281a42e JB |
3222 | form. |
3223 | @xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}. | |
9fb4dd36 JB |
3224 | |
3225 | @item REGISTER_CONVERT_TO_RAW(@var{type}, @var{reg}, @var{from}, @var{to}) | |
56caf160 | 3226 | @findex REGISTER_CONVERT_TO_RAW |
9fb4dd36 | 3227 | Convert the value of register @var{reg} from its virtual form to its raw |
4281a42e JB |
3228 | form. |
3229 | @xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}. | |
9fb4dd36 | 3230 | |
e5419804 JB |
3231 | @item RETURN_VALUE_ON_STACK(@var{type}) |
3232 | @findex RETURN_VALUE_ON_STACK | |
3233 | @cindex returning structures by value | |
3234 | @cindex structures, returning by value | |
3235 | ||
3236 | Return non-zero if values of type TYPE are returned on the stack, using | |
3237 | the ``struct convention'' (i.e., the caller provides a pointer to a | |
3238 | buffer in which the callee should store the return value). This | |
3239 | controls how the @samp{finish} command finds a function's return value, | |
3240 | and whether an inferior function call reserves space on the stack for | |
3241 | the return value. | |
3242 | ||
3243 | The full logic @value{GDBN} uses here is kind of odd. | |
e5419804 | 3244 | |
56caf160 | 3245 | @itemize @bullet |
e5419804 JB |
3246 | @item |
3247 | If the type being returned by value is not a structure, union, or array, | |
3248 | and @code{RETURN_VALUE_ON_STACK} returns zero, then @value{GDBN} | |
3249 | concludes the value is not returned using the struct convention. | |
3250 | ||
3251 | @item | |
3252 | Otherwise, @value{GDBN} calls @code{USE_STRUCT_CONVENTION} (see below). | |
3253 | If that returns non-zero, @value{GDBN} assumes the struct convention is | |
3254 | in use. | |
e5419804 JB |
3255 | @end itemize |
3256 | ||
3257 | In other words, to indicate that a given type is returned by value using | |
3258 | the struct convention, that type must be either a struct, union, array, | |
3259 | or something @code{RETURN_VALUE_ON_STACK} likes, @emph{and} something | |
3260 | that @code{USE_STRUCT_CONVENTION} likes. | |
3261 | ||
56caf160 | 3262 | Note that, in C and C@t{++}, arrays are never returned by value. In those |
e5419804 JB |
3263 | languages, these predicates will always see a pointer type, never an |
3264 | array type. All the references above to arrays being returned by value | |
3265 | apply only to other languages. | |
3266 | ||
b0ed3589 | 3267 | @item SOFTWARE_SINGLE_STEP_P() |
56caf160 | 3268 | @findex SOFTWARE_SINGLE_STEP_P |
c906108c | 3269 | Define this as 1 if the target does not have a hardware single-step |
56caf160 | 3270 | mechanism. The macro @code{SOFTWARE_SINGLE_STEP} must also be defined. |
c906108c | 3271 | |
56caf160 EZ |
3272 | @item SOFTWARE_SINGLE_STEP(@var{signal}, @var{insert_breapoints_p}) |
3273 | @findex SOFTWARE_SINGLE_STEP | |
3274 | A function that inserts or removes (depending on | |
c906108c | 3275 | @var{insert_breapoints_p}) breakpoints at each possible destinations of |
56caf160 | 3276 | the next instruction. See @file{sparc-tdep.c} and @file{rs6000-tdep.c} |
c906108c SS |
3277 | for examples. |
3278 | ||
da59e081 | 3279 | @item SOFUN_ADDRESS_MAYBE_MISSING |
56caf160 | 3280 | @findex SOFUN_ADDRESS_MAYBE_MISSING |
da59e081 JM |
3281 | Somebody clever observed that, the more actual addresses you have in the |
3282 | debug information, the more time the linker has to spend relocating | |
3283 | them. So whenever there's some other way the debugger could find the | |
3284 | address it needs, you should omit it from the debug info, to make | |
3285 | linking faster. | |
3286 | ||
3287 | @code{SOFUN_ADDRESS_MAYBE_MISSING} indicates that a particular set of | |
3288 | hacks of this sort are in use, affecting @code{N_SO} and @code{N_FUN} | |
3289 | entries in stabs-format debugging information. @code{N_SO} stabs mark | |
3290 | the beginning and ending addresses of compilation units in the text | |
3291 | segment. @code{N_FUN} stabs mark the starts and ends of functions. | |
3292 | ||
3293 | @code{SOFUN_ADDRESS_MAYBE_MISSING} means two things: | |
da59e081 | 3294 | |
56caf160 | 3295 | @itemize @bullet |
da59e081 JM |
3296 | @item |
3297 | @code{N_FUN} stabs have an address of zero. Instead, you should find the | |
3298 | addresses where the function starts by taking the function name from | |
56caf160 EZ |
3299 | the stab, and then looking that up in the minsyms (the |
3300 | linker/assembler symbol table). In other words, the stab has the | |
3301 | name, and the linker/assembler symbol table is the only place that carries | |
da59e081 JM |
3302 | the address. |
3303 | ||
3304 | @item | |
3305 | @code{N_SO} stabs have an address of zero, too. You just look at the | |
3306 | @code{N_FUN} stabs that appear before and after the @code{N_SO} stab, | |
3307 | and guess the starting and ending addresses of the compilation unit from | |
3308 | them. | |
da59e081 JM |
3309 | @end itemize |
3310 | ||
c906108c | 3311 | @item PCC_SOL_BROKEN |
56caf160 | 3312 | @findex PCC_SOL_BROKEN |
c906108c SS |
3313 | (Used only in the Convex target.) |
3314 | ||
3315 | @item PC_IN_CALL_DUMMY | |
56caf160 EZ |
3316 | @findex PC_IN_CALL_DUMMY |
3317 | See @file{inferior.h}. | |
c906108c SS |
3318 | |
3319 | @item PC_LOAD_SEGMENT | |
56caf160 | 3320 | @findex PC_LOAD_SEGMENT |
c906108c SS |
3321 | If defined, print information about the load segment for the program |
3322 | counter. (Defined only for the RS/6000.) | |
3323 | ||
3324 | @item PC_REGNUM | |
56caf160 | 3325 | @findex PC_REGNUM |
c906108c | 3326 | If the program counter is kept in a register, then define this macro to |
cce74817 JM |
3327 | be the number (greater than or equal to zero) of that register. |
3328 | ||
3329 | This should only need to be defined if @code{TARGET_READ_PC} and | |
3330 | @code{TARGET_WRITE_PC} are not defined. | |
c906108c SS |
3331 | |
3332 | @item NPC_REGNUM | |
56caf160 | 3333 | @findex NPC_REGNUM |
c906108c SS |
3334 | The number of the ``next program counter'' register, if defined. |
3335 | ||
3336 | @item NNPC_REGNUM | |
56caf160 | 3337 | @findex NNPC_REGNUM |
c906108c SS |
3338 | The number of the ``next next program counter'' register, if defined. |
3339 | Currently, this is only defined for the Motorola 88K. | |
3340 | ||
2df3850c | 3341 | @item PARM_BOUNDARY |
56caf160 | 3342 | @findex PARM_BOUNDARY |
2df3850c JM |
3343 | If non-zero, round arguments to a boundary of this many bits before |
3344 | pushing them on the stack. | |
3345 | ||
56caf160 EZ |
3346 | @item PRINT_REGISTER_HOOK (@var{regno}) |
3347 | @findex PRINT_REGISTER_HOOK | |
c906108c SS |
3348 | If defined, this must be a function that prints the contents of the |
3349 | given register to standard output. | |
3350 | ||
3351 | @item PRINT_TYPELESS_INTEGER | |
56caf160 | 3352 | @findex PRINT_TYPELESS_INTEGER |
c906108c SS |
3353 | This is an obscure substitute for @code{print_longest} that seems to |
3354 | have been defined for the Convex target. | |
3355 | ||
3356 | @item PROCESS_LINENUMBER_HOOK | |
56caf160 | 3357 | @findex PROCESS_LINENUMBER_HOOK |
c906108c SS |
3358 | A hook defined for XCOFF reading. |
3359 | ||
3360 | @item PROLOGUE_FIRSTLINE_OVERLAP | |
56caf160 | 3361 | @findex PROLOGUE_FIRSTLINE_OVERLAP |
c906108c SS |
3362 | (Only used in unsupported Convex configuration.) |
3363 | ||
3364 | @item PS_REGNUM | |
56caf160 | 3365 | @findex PS_REGNUM |
c906108c SS |
3366 | If defined, this is the number of the processor status register. (This |
3367 | definition is only used in generic code when parsing "$ps".) | |
3368 | ||
3369 | @item POP_FRAME | |
56caf160 EZ |
3370 | @findex POP_FRAME |
3371 | @findex call_function_by_hand | |
3372 | @findex return_command | |
c906108c | 3373 | Used in @samp{call_function_by_hand} to remove an artificial stack |
1c6147de | 3374 | frame and in @samp{return_command} to remove a real stack frame. |
c906108c | 3375 | |
56caf160 EZ |
3376 | @item PUSH_ARGUMENTS (@var{nargs}, @var{args}, @var{sp}, @var{struct_return}, @var{struct_addr}) |
3377 | @findex PUSH_ARGUMENTS | |
392a587b | 3378 | Define this to push arguments onto the stack for inferior function |
56caf160 | 3379 | call. Returns the updated stack pointer value. |
c906108c SS |
3380 | |
3381 | @item PUSH_DUMMY_FRAME | |
56caf160 | 3382 | @findex PUSH_DUMMY_FRAME |
c906108c SS |
3383 | Used in @samp{call_function_by_hand} to create an artificial stack frame. |
3384 | ||
3385 | @item REGISTER_BYTES | |
56caf160 | 3386 | @findex REGISTER_BYTES |
25822942 | 3387 | The total amount of space needed to store @value{GDBN}'s copy of the machine's |
c906108c SS |
3388 | register state. |
3389 | ||
56caf160 EZ |
3390 | @item REGISTER_NAME(@var{i}) |
3391 | @findex REGISTER_NAME | |
3392 | Return the name of register @var{i} as a string. May return @code{NULL} | |
3393 | or @code{NUL} to indicate that register @var{i} is not valid. | |
c906108c | 3394 | |
7a292a7a | 3395 | @item REGISTER_NAMES |
56caf160 EZ |
3396 | @findex REGISTER_NAMES |
3397 | Deprecated in favor of @code{REGISTER_NAME}. | |
7a292a7a | 3398 | |
56caf160 EZ |
3399 | @item REG_STRUCT_HAS_ADDR (@var{gcc_p}, @var{type}) |
3400 | @findex REG_STRUCT_HAS_ADDR | |
c906108c SS |
3401 | Define this to return 1 if the given type will be passed by pointer |
3402 | rather than directly. | |
3403 | ||
56caf160 EZ |
3404 | @item SAVE_DUMMY_FRAME_TOS (@var{sp}) |
3405 | @findex SAVE_DUMMY_FRAME_TOS | |
43ff13b4 JM |
3406 | Used in @samp{call_function_by_hand} to notify the target dependent code |
3407 | of the top-of-stack value that will be passed to the the inferior code. | |
56caf160 | 3408 | This is the value of the @code{SP} after both the dummy frame and space |
43ff13b4 JM |
3409 | for parameters/results have been allocated on the stack. |
3410 | ||
c906108c | 3411 | @item SDB_REG_TO_REGNUM |
56caf160 | 3412 | @findex SDB_REG_TO_REGNUM |
25822942 | 3413 | Define this to convert sdb register numbers into @value{GDBN} regnums. If not |
c906108c SS |
3414 | defined, no conversion will be done. |
3415 | ||
3416 | @item SHIFT_INST_REGS | |
56caf160 | 3417 | @findex SHIFT_INST_REGS |
c906108c SS |
3418 | (Only used for m88k targets.) |
3419 | ||
c2c6d25f | 3420 | @item SKIP_PERMANENT_BREAKPOINT |
56caf160 | 3421 | @findex SKIP_PERMANENT_BREAKPOINT |
25822942 | 3422 | Advance the inferior's PC past a permanent breakpoint. @value{GDBN} normally |
c2c6d25f JM |
3423 | steps over a breakpoint by removing it, stepping one instruction, and |
3424 | re-inserting the breakpoint. However, permanent breakpoints are | |
3425 | hardwired into the inferior, and can't be removed, so this strategy | |
56caf160 | 3426 | doesn't work. Calling @code{SKIP_PERMANENT_BREAKPOINT} adjusts the processor's |
c2c6d25f JM |
3427 | state so that execution will resume just after the breakpoint. This |
3428 | macro does the right thing even when the breakpoint is in the delay slot | |
3429 | of a branch or jump. | |
3430 | ||
56caf160 EZ |
3431 | @item SKIP_PROLOGUE (@var{pc}) |
3432 | @findex SKIP_PROLOGUE | |
b83266a0 SS |
3433 | A C expression that returns the address of the ``real'' code beyond the |
3434 | function entry prologue found at @var{pc}. | |
c906108c SS |
3435 | |
3436 | @item SKIP_PROLOGUE_FRAMELESS_P | |
56caf160 | 3437 | @findex SKIP_PROLOGUE_FRAMELESS_P |
b83266a0 SS |
3438 | A C expression that should behave similarly, but that can stop as soon |
3439 | as the function is known to have a frame. If not defined, | |
c906108c SS |
3440 | @code{SKIP_PROLOGUE} will be used instead. |
3441 | ||
56caf160 EZ |
3442 | @item SKIP_TRAMPOLINE_CODE (@var{pc}) |
3443 | @findex SKIP_TRAMPOLINE_CODE | |
c906108c SS |
3444 | If the target machine has trampoline code that sits between callers and |
3445 | the functions being called, then define this macro to return a new PC | |
3446 | that is at the start of the real function. | |
3447 | ||
3448 | @item SP_REGNUM | |
56caf160 | 3449 | @findex SP_REGNUM |
cce74817 JM |
3450 | If the stack-pointer is kept in a register, then define this macro to be |
3451 | the number (greater than or equal to zero) of that register. | |
3452 | ||
3453 | This should only need to be defined if @code{TARGET_WRITE_SP} and | |
3454 | @code{TARGET_WRITE_SP} are not defined. | |
c906108c SS |
3455 | |
3456 | @item STAB_REG_TO_REGNUM | |
56caf160 | 3457 | @findex STAB_REG_TO_REGNUM |
c906108c | 3458 | Define this to convert stab register numbers (as gotten from `r' |
25822942 | 3459 | declarations) into @value{GDBN} regnums. If not defined, no conversion will be |
c906108c SS |
3460 | done. |
3461 | ||
56caf160 EZ |
3462 | @item STACK_ALIGN (@var{addr}) |
3463 | @findex STACK_ALIGN | |
c906108c SS |
3464 | Define this to adjust the address to the alignment required for the |
3465 | processor's stack. | |
3466 | ||
56caf160 EZ |
3467 | @item STEP_SKIPS_DELAY (@var{addr}) |
3468 | @findex STEP_SKIPS_DELAY | |
c906108c SS |
3469 | Define this to return true if the address is of an instruction with a |
3470 | delay slot. If a breakpoint has been placed in the instruction's delay | |
25822942 | 3471 | slot, @value{GDBN} will single-step over that instruction before resuming |
c906108c SS |
3472 | normally. Currently only defined for the Mips. |
3473 | ||
56caf160 EZ |
3474 | @item STORE_RETURN_VALUE (@var{type}, @var{valbuf}) |
3475 | @findex STORE_RETURN_VALUE | |
c906108c SS |
3476 | A C expression that stores a function return value of type @var{type}, |
3477 | where @var{valbuf} is the address of the value to be stored. | |
3478 | ||
3479 | @item SUN_FIXED_LBRAC_BUG | |
56caf160 | 3480 | @findex SUN_FIXED_LBRAC_BUG |
c906108c SS |
3481 | (Used only for Sun-3 and Sun-4 targets.) |
3482 | ||
3483 | @item SYMBOL_RELOADING_DEFAULT | |
56caf160 EZ |
3484 | @findex SYMBOL_RELOADING_DEFAULT |
3485 | The default value of the ``symbol-reloading'' variable. (Never defined in | |
c906108c SS |
3486 | current sources.) |
3487 | ||
3488 | @item TARGET_BYTE_ORDER_DEFAULT | |
56caf160 | 3489 | @findex TARGET_BYTE_ORDER_DEFAULT |
c906108c | 3490 | The ordering of bytes in the target. This must be either |
778eb05e | 3491 | @code{BIG_ENDIAN} or @code{BFD_ENDIAN_LITTLE}. This macro replaces |
56caf160 | 3492 | @code{TARGET_BYTE_ORDER} which is deprecated. |
c906108c SS |
3493 | |
3494 | @item TARGET_BYTE_ORDER_SELECTABLE_P | |
56caf160 | 3495 | @findex TARGET_BYTE_ORDER_SELECTABLE_P |
c906108c | 3496 | Non-zero if the target has both @code{BIG_ENDIAN} and |
778eb05e | 3497 | @code{BFD_ENDIAN_LITTLE} variants. This macro replaces |
56caf160 | 3498 | @code{TARGET_BYTE_ORDER_SELECTABLE} which is deprecated. |
c906108c SS |
3499 | |
3500 | @item TARGET_CHAR_BIT | |
56caf160 | 3501 | @findex TARGET_CHAR_BIT |
c906108c SS |
3502 | Number of bits in a char; defaults to 8. |
3503 | ||
3504 | @item TARGET_COMPLEX_BIT | |
56caf160 | 3505 | @findex TARGET_COMPLEX_BIT |
c906108c SS |
3506 | Number of bits in a complex number; defaults to @code{2 * TARGET_FLOAT_BIT}. |
3507 | ||
ac9a91a7 JM |
3508 | At present this macro is not used. |
3509 | ||
c906108c | 3510 | @item TARGET_DOUBLE_BIT |
56caf160 | 3511 | @findex TARGET_DOUBLE_BIT |
c906108c SS |
3512 | Number of bits in a double float; defaults to @code{8 * TARGET_CHAR_BIT}. |
3513 | ||
3514 | @item TARGET_DOUBLE_COMPLEX_BIT | |
56caf160 | 3515 | @findex TARGET_DOUBLE_COMPLEX_BIT |
c906108c SS |
3516 | Number of bits in a double complex; defaults to @code{2 * TARGET_DOUBLE_BIT}. |
3517 | ||
ac9a91a7 JM |
3518 | At present this macro is not used. |
3519 | ||
c906108c | 3520 | @item TARGET_FLOAT_BIT |
56caf160 | 3521 | @findex TARGET_FLOAT_BIT |
c906108c SS |
3522 | Number of bits in a float; defaults to @code{4 * TARGET_CHAR_BIT}. |
3523 | ||
3524 | @item TARGET_INT_BIT | |
56caf160 | 3525 | @findex TARGET_INT_BIT |
c906108c SS |
3526 | Number of bits in an integer; defaults to @code{4 * TARGET_CHAR_BIT}. |
3527 | ||
3528 | @item TARGET_LONG_BIT | |
56caf160 | 3529 | @findex TARGET_LONG_BIT |
c906108c SS |
3530 | Number of bits in a long integer; defaults to @code{4 * TARGET_CHAR_BIT}. |
3531 | ||
3532 | @item TARGET_LONG_DOUBLE_BIT | |
56caf160 | 3533 | @findex TARGET_LONG_DOUBLE_BIT |
c906108c SS |
3534 | Number of bits in a long double float; |
3535 | defaults to @code{2 * TARGET_DOUBLE_BIT}. | |
3536 | ||
3537 | @item TARGET_LONG_LONG_BIT | |
56caf160 | 3538 | @findex TARGET_LONG_LONG_BIT |
c906108c SS |
3539 | Number of bits in a long long integer; defaults to @code{2 * TARGET_LONG_BIT}. |
3540 | ||
3541 | @item TARGET_PTR_BIT | |
56caf160 | 3542 | @findex TARGET_PTR_BIT |
c906108c SS |
3543 | Number of bits in a pointer; defaults to @code{TARGET_INT_BIT}. |
3544 | ||
3545 | @item TARGET_SHORT_BIT | |
56caf160 | 3546 | @findex TARGET_SHORT_BIT |
c906108c SS |
3547 | Number of bits in a short integer; defaults to @code{2 * TARGET_CHAR_BIT}. |
3548 | ||
3549 | @item TARGET_READ_PC | |
56caf160 EZ |
3550 | @findex TARGET_READ_PC |
3551 | @itemx TARGET_WRITE_PC (@var{val}, @var{pid}) | |
3552 | @findex TARGET_WRITE_PC | |
3553 | @itemx TARGET_READ_SP | |
3554 | @findex TARGET_READ_SP | |
3555 | @itemx TARGET_WRITE_SP | |
3556 | @findex TARGET_WRITE_SP | |
3557 | @itemx TARGET_READ_FP | |
3558 | @findex TARGET_READ_FP | |
3559 | @itemx TARGET_WRITE_FP | |
3560 | @findex TARGET_WRITE_FP | |
3561 | @findex read_pc | |
3562 | @findex write_pc | |
3563 | @findex read_sp | |
3564 | @findex write_sp | |
3565 | @findex read_fp | |
3566 | @findex write_fp | |
c906108c SS |
3567 | These change the behavior of @code{read_pc}, @code{write_pc}, |
3568 | @code{read_sp}, @code{write_sp}, @code{read_fp} and @code{write_fp}. | |
25822942 | 3569 | For most targets, these may be left undefined. @value{GDBN} will call the read |
c906108c SS |
3570 | and write register functions with the relevant @code{_REGNUM} argument. |
3571 | ||
3572 | These macros are useful when a target keeps one of these registers in a | |
3573 | hard to get at place; for example, part in a segment register and part | |
3574 | in an ordinary register. | |
3575 | ||
56caf160 EZ |
3576 | @item TARGET_VIRTUAL_FRAME_POINTER(@var{pc}, @var{regp}, @var{offsetp}) |
3577 | @findex TARGET_VIRTUAL_FRAME_POINTER | |
c906108c | 3578 | Returns a @code{(register, offset)} pair representing the virtual |
56caf160 | 3579 | frame pointer in use at the code address @var{pc}. If virtual |
c906108c SS |
3580 | frame pointers are not used, a default definition simply returns |
3581 | @code{FP_REGNUM}, with an offset of zero. | |
3582 | ||
9742079a EZ |
3583 | @item TARGET_HAS_HARDWARE_WATCHPOINTS |
3584 | If non-zero, the target has support for hardware-assisted | |
3585 | watchpoints. @xref{Algorithms, watchpoints}, for more details and | |
3586 | other related macros. | |
3587 | ||
7ccaa899 EZ |
3588 | @item TARGET_PRINT_INSN (@var{addr}, @var{info}) |
3589 | @findex TARGET_PRINT_INSN | |
3590 | This is the function used by @value{GDBN} to print an assembly | |
3591 | instruction. It prints the instruction at address @var{addr} in | |
3592 | debugged memory and returns the length of the instruction, in bytes. If | |
3593 | a target doesn't define its own printing routine, it defaults to an | |
3594 | accessor function for the global pointer @code{tm_print_insn}. This | |
3595 | usually points to a function in the @code{opcodes} library (@pxref{Support | |
3596 | Libraries, ,Opcodes}). @var{info} is a structure (of type | |
3597 | @code{disassemble_info}) defined in @file{include/dis-asm.h} used to | |
3598 | pass information to the instruction decoding routine. | |
3599 | ||
56caf160 EZ |
3600 | @item USE_STRUCT_CONVENTION (@var{gcc_p}, @var{type}) |
3601 | @findex USE_STRUCT_CONVENTION | |
c906108c SS |
3602 | If defined, this must be an expression that is nonzero if a value of the |
3603 | given @var{type} being returned from a function must have space | |
3604 | allocated for it on the stack. @var{gcc_p} is true if the function | |
3605 | being considered is known to have been compiled by GCC; this is helpful | |
3606 | for systems where GCC is known to use different calling convention than | |
3607 | other compilers. | |
3608 | ||
56caf160 EZ |
3609 | @item VARIABLES_INSIDE_BLOCK (@var{desc}, @var{gcc_p}) |
3610 | @findex VARIABLES_INSIDE_BLOCK | |
c906108c SS |
3611 | For dbx-style debugging information, if the compiler puts variable |
3612 | declarations inside LBRAC/RBRAC blocks, this should be defined to be | |
3613 | nonzero. @var{desc} is the value of @code{n_desc} from the | |
25822942 | 3614 | @code{N_RBRAC} symbol, and @var{gcc_p} is true if @value{GDBN} has noticed the |
c906108c SS |
3615 | presence of either the @code{GCC_COMPILED_SYMBOL} or the |
3616 | @code{GCC2_COMPILED_SYMBOL}. By default, this is 0. | |
3617 | ||
56caf160 EZ |
3618 | @item OS9K_VARIABLES_INSIDE_BLOCK (@var{desc}, @var{gcc_p}) |
3619 | @findex OS9K_VARIABLES_INSIDE_BLOCK | |
c906108c | 3620 | Similarly, for OS/9000. Defaults to 1. |
c906108c SS |
3621 | @end table |
3622 | ||
3623 | Motorola M68K target conditionals. | |
3624 | ||
56caf160 | 3625 | @ftable @code |
c906108c SS |
3626 | @item BPT_VECTOR |
3627 | Define this to be the 4-bit location of the breakpoint trap vector. If | |
3628 | not defined, it will default to @code{0xf}. | |
3629 | ||
3630 | @item REMOTE_BPT_VECTOR | |
3631 | Defaults to @code{1}. | |
56caf160 | 3632 | @end ftable |
c906108c SS |
3633 | |
3634 | @section Adding a New Target | |
3635 | ||
56caf160 | 3636 | @cindex adding a target |
af6c57ea | 3637 | The following files add a target to @value{GDBN}: |
c906108c SS |
3638 | |
3639 | @table @file | |
56caf160 | 3640 | @vindex TDEPFILES |
c906108c SS |
3641 | @item gdb/config/@var{arch}/@var{ttt}.mt |
3642 | Contains a Makefile fragment specific to this target. Specifies what | |
3643 | object files are needed for target @var{ttt}, by defining | |
104c1213 JM |
3644 | @samp{TDEPFILES=@dots{}} and @samp{TDEPLIBS=@dots{}}. Also specifies |
3645 | the header file which describes @var{ttt}, by defining @samp{TM_FILE= | |
3646 | tm-@var{ttt}.h}. | |
3647 | ||
3648 | You can also define @samp{TM_CFLAGS}, @samp{TM_CLIBS}, @samp{TM_CDEPS}, | |
3649 | but these are now deprecated, replaced by autoconf, and may go away in | |
25822942 | 3650 | future versions of @value{GDBN}. |
c906108c | 3651 | |
c906108c SS |
3652 | @item gdb/@var{ttt}-tdep.c |
3653 | Contains any miscellaneous code required for this target machine. On | |
3654 | some machines it doesn't exist at all. Sometimes the macros in | |
3655 | @file{tm-@var{ttt}.h} become very complicated, so they are implemented | |
3656 | as functions here instead, and the macro is simply defined to call the | |
3657 | function. This is vastly preferable, since it is easier to understand | |
3658 | and debug. | |
3659 | ||
af6c57ea AC |
3660 | @item gdb/@var{arch}-tdep.c |
3661 | @itemx gdb/@var{arch}-tdep.h | |
3662 | This often exists to describe the basic layout of the target machine's | |
3663 | processor chip (registers, stack, etc.). If used, it is included by | |
3664 | @file{@var{ttt}-tdep.h}. It can be shared among many targets that use | |
3665 | the same processor. | |
3666 | ||
3667 | @item gdb/config/@var{arch}/tm-@var{ttt}.h | |
3668 | (@file{tm.h} is a link to this file, created by @code{configure}). Contains | |
3669 | macro definitions about the target machine's registers, stack frame | |
3670 | format and instructions. | |
3671 | ||
3672 | New targets do not need this file and should not create it. | |
3673 | ||
c906108c SS |
3674 | @item gdb/config/@var{arch}/tm-@var{arch}.h |
3675 | This often exists to describe the basic layout of the target machine's | |
56caf160 | 3676 | processor chip (registers, stack, etc.). If used, it is included by |
c906108c SS |
3677 | @file{tm-@var{ttt}.h}. It can be shared among many targets that use the |
3678 | same processor. | |
3679 | ||
af6c57ea AC |
3680 | New targets do not need this file and should not create it. |
3681 | ||
c906108c SS |
3682 | @end table |
3683 | ||
3684 | If you are adding a new operating system for an existing CPU chip, add a | |
3685 | @file{config/tm-@var{os}.h} file that describes the operating system | |
3686 | facilities that are unusual (extra symbol table info; the breakpoint | |
56caf160 | 3687 | instruction needed; etc.). Then write a @file{@var{arch}/tm-@var{os}.h} |
c906108c SS |
3688 | that just @code{#include}s @file{tm-@var{arch}.h} and |
3689 | @file{config/tm-@var{os}.h}. | |
3690 | ||
3691 | ||
3692 | @node Target Vector Definition | |
3693 | ||
3694 | @chapter Target Vector Definition | |
56caf160 | 3695 | @cindex target vector |
c906108c | 3696 | |
56caf160 EZ |
3697 | The target vector defines the interface between @value{GDBN}'s |
3698 | abstract handling of target systems, and the nitty-gritty code that | |
3699 | actually exercises control over a process or a serial port. | |
3700 | @value{GDBN} includes some 30-40 different target vectors; however, | |
3701 | each configuration of @value{GDBN} includes only a few of them. | |
c906108c SS |
3702 | |
3703 | @section File Targets | |
3704 | ||
3705 | Both executables and core files have target vectors. | |
3706 | ||
3707 | @section Standard Protocol and Remote Stubs | |
3708 | ||
56caf160 EZ |
3709 | @value{GDBN}'s file @file{remote.c} talks a serial protocol to code |
3710 | that runs in the target system. @value{GDBN} provides several sample | |
3711 | @dfn{stubs} that can be integrated into target programs or operating | |
3712 | systems for this purpose; they are named @file{*-stub.c}. | |
c906108c | 3713 | |
56caf160 EZ |
3714 | The @value{GDBN} user's manual describes how to put such a stub into |
3715 | your target code. What follows is a discussion of integrating the | |
3716 | SPARC stub into a complicated operating system (rather than a simple | |
3717 | program), by Stu Grossman, the author of this stub. | |
c906108c SS |
3718 | |
3719 | The trap handling code in the stub assumes the following upon entry to | |
56caf160 | 3720 | @code{trap_low}: |
c906108c SS |
3721 | |
3722 | @enumerate | |
56caf160 EZ |
3723 | @item |
3724 | %l1 and %l2 contain pc and npc respectively at the time of the trap; | |
c906108c | 3725 | |
56caf160 EZ |
3726 | @item |
3727 | traps are disabled; | |
c906108c | 3728 | |
56caf160 EZ |
3729 | @item |
3730 | you are in the correct trap window. | |
c906108c SS |
3731 | @end enumerate |
3732 | ||
3733 | As long as your trap handler can guarantee those conditions, then there | |
56caf160 | 3734 | is no reason why you shouldn't be able to ``share'' traps with the stub. |
c906108c SS |
3735 | The stub has no requirement that it be jumped to directly from the |
3736 | hardware trap vector. That is why it calls @code{exceptionHandler()}, | |
3737 | which is provided by the external environment. For instance, this could | |
56caf160 | 3738 | set up the hardware traps to actually execute code which calls the stub |
c906108c SS |
3739 | first, and then transfers to its own trap handler. |
3740 | ||
3741 | For the most point, there probably won't be much of an issue with | |
56caf160 | 3742 | ``sharing'' traps, as the traps we use are usually not used by the kernel, |
c906108c SS |
3743 | and often indicate unrecoverable error conditions. Anyway, this is all |
3744 | controlled by a table, and is trivial to modify. The most important | |
3745 | trap for us is for @code{ta 1}. Without that, we can't single step or | |
3746 | do breakpoints. Everything else is unnecessary for the proper operation | |
3747 | of the debugger/stub. | |
3748 | ||
3749 | From reading the stub, it's probably not obvious how breakpoints work. | |
25822942 | 3750 | They are simply done by deposit/examine operations from @value{GDBN}. |
c906108c SS |
3751 | |
3752 | @section ROM Monitor Interface | |
3753 | ||
3754 | @section Custom Protocols | |
3755 | ||
3756 | @section Transport Layer | |
3757 | ||
3758 | @section Builtin Simulator | |
3759 | ||
3760 | ||
3761 | @node Native Debugging | |
3762 | ||
3763 | @chapter Native Debugging | |
56caf160 | 3764 | @cindex native debugging |
c906108c | 3765 | |
25822942 | 3766 | Several files control @value{GDBN}'s configuration for native support: |
c906108c SS |
3767 | |
3768 | @table @file | |
56caf160 | 3769 | @vindex NATDEPFILES |
c906108c SS |
3770 | @item gdb/config/@var{arch}/@var{xyz}.mh |
3771 | Specifies Makefile fragments needed when hosting @emph{or native} on | |
3772 | machine @var{xyz}. In particular, this lists the required | |
3773 | native-dependent object files, by defining @samp{NATDEPFILES=@dots{}}. | |
3774 | Also specifies the header file which describes native support on | |
3775 | @var{xyz}, by defining @samp{NAT_FILE= nm-@var{xyz}.h}. You can also | |
3776 | define @samp{NAT_CFLAGS}, @samp{NAT_ADD_FILES}, @samp{NAT_CLIBS}, | |
3777 | @samp{NAT_CDEPS}, etc.; see @file{Makefile.in}. | |
3778 | ||
3779 | @item gdb/config/@var{arch}/nm-@var{xyz}.h | |
56caf160 | 3780 | (@file{nm.h} is a link to this file, created by @code{configure}). Contains C |
c906108c SS |
3781 | macro definitions describing the native system environment, such as |
3782 | child process control and core file support. | |
3783 | ||
3784 | @item gdb/@var{xyz}-nat.c | |
3785 | Contains any miscellaneous C code required for this native support of | |
3786 | this machine. On some machines it doesn't exist at all. | |
c906108c SS |
3787 | @end table |
3788 | ||
3789 | There are some ``generic'' versions of routines that can be used by | |
3790 | various systems. These can be customized in various ways by macros | |
3791 | defined in your @file{nm-@var{xyz}.h} file. If these routines work for | |
3792 | the @var{xyz} host, you can just include the generic file's name (with | |
3793 | @samp{.o}, not @samp{.c}) in @code{NATDEPFILES}. | |
3794 | ||
3795 | Otherwise, if your machine needs custom support routines, you will need | |
3796 | to write routines that perform the same functions as the generic file. | |
56caf160 | 3797 | Put them into @file{@var{xyz}-nat.c}, and put @file{@var{xyz}-nat.o} |
c906108c SS |
3798 | into @code{NATDEPFILES}. |
3799 | ||
3800 | @table @file | |
c906108c SS |
3801 | @item inftarg.c |
3802 | This contains the @emph{target_ops vector} that supports Unix child | |
3803 | processes on systems which use ptrace and wait to control the child. | |
3804 | ||
3805 | @item procfs.c | |
3806 | This contains the @emph{target_ops vector} that supports Unix child | |
3807 | processes on systems which use /proc to control the child. | |
3808 | ||
3809 | @item fork-child.c | |
56caf160 EZ |
3810 | This does the low-level grunge that uses Unix system calls to do a ``fork |
3811 | and exec'' to start up a child process. | |
c906108c SS |
3812 | |
3813 | @item infptrace.c | |
3814 | This is the low level interface to inferior processes for systems using | |
3815 | the Unix @code{ptrace} call in a vanilla way. | |
c906108c SS |
3816 | @end table |
3817 | ||
3818 | @section Native core file Support | |
56caf160 | 3819 | @cindex native core files |
c906108c SS |
3820 | |
3821 | @table @file | |
56caf160 | 3822 | @findex fetch_core_registers |
c906108c SS |
3823 | @item core-aout.c::fetch_core_registers() |
3824 | Support for reading registers out of a core file. This routine calls | |
3825 | @code{register_addr()}, see below. Now that BFD is used to read core | |
3826 | files, virtually all machines should use @code{core-aout.c}, and should | |
3827 | just provide @code{fetch_core_registers} in @code{@var{xyz}-nat.c} (or | |
3828 | @code{REGISTER_U_ADDR} in @code{nm-@var{xyz}.h}). | |
3829 | ||
3830 | @item core-aout.c::register_addr() | |
3831 | If your @code{nm-@var{xyz}.h} file defines the macro | |
3832 | @code{REGISTER_U_ADDR(addr, blockend, regno)}, it should be defined to | |
25822942 | 3833 | set @code{addr} to the offset within the @samp{user} struct of @value{GDBN} |
c906108c SS |
3834 | register number @code{regno}. @code{blockend} is the offset within the |
3835 | ``upage'' of @code{u.u_ar0}. If @code{REGISTER_U_ADDR} is defined, | |
3836 | @file{core-aout.c} will define the @code{register_addr()} function and | |
3837 | use the macro in it. If you do not define @code{REGISTER_U_ADDR}, but | |
3838 | you are using the standard @code{fetch_core_registers()}, you will need | |
3839 | to define your own version of @code{register_addr()}, put it into your | |
3840 | @code{@var{xyz}-nat.c} file, and be sure @code{@var{xyz}-nat.o} is in | |
3841 | the @code{NATDEPFILES} list. If you have your own | |
3842 | @code{fetch_core_registers()}, you may not need a separate | |
3843 | @code{register_addr()}. Many custom @code{fetch_core_registers()} | |
3844 | implementations simply locate the registers themselves.@refill | |
c906108c SS |
3845 | @end table |
3846 | ||
25822942 | 3847 | When making @value{GDBN} run native on a new operating system, to make it |
c906108c SS |
3848 | possible to debug core files, you will need to either write specific |
3849 | code for parsing your OS's core files, or customize | |
3850 | @file{bfd/trad-core.c}. First, use whatever @code{#include} files your | |
3851 | machine uses to define the struct of registers that is accessible | |
3852 | (possibly in the u-area) in a core file (rather than | |
3853 | @file{machine/reg.h}), and an include file that defines whatever header | |
56caf160 EZ |
3854 | exists on a core file (e.g. the u-area or a @code{struct core}). Then |
3855 | modify @code{trad_unix_core_file_p} to use these values to set up the | |
c906108c SS |
3856 | section information for the data segment, stack segment, any other |
3857 | segments in the core file (perhaps shared library contents or control | |
3858 | information), ``registers'' segment, and if there are two discontiguous | |
3859 | sets of registers (e.g. integer and float), the ``reg2'' segment. This | |
3860 | section information basically delimits areas in the core file in a | |
3861 | standard way, which the section-reading routines in BFD know how to seek | |
3862 | around in. | |
3863 | ||
25822942 | 3864 | Then back in @value{GDBN}, you need a matching routine called |
56caf160 | 3865 | @code{fetch_core_registers}. If you can use the generic one, it's in |
c906108c SS |
3866 | @file{core-aout.c}; if not, it's in your @file{@var{xyz}-nat.c} file. |
3867 | It will be passed a char pointer to the entire ``registers'' segment, | |
3868 | its length, and a zero; or a char pointer to the entire ``regs2'' | |
3869 | segment, its length, and a 2. The routine should suck out the supplied | |
25822942 | 3870 | register values and install them into @value{GDBN}'s ``registers'' array. |
c906108c SS |
3871 | |
3872 | If your system uses @file{/proc} to control processes, and uses ELF | |
3873 | format core files, then you may be able to use the same routines for | |
3874 | reading the registers out of processes and out of core files. | |
3875 | ||
3876 | @section ptrace | |
3877 | ||
3878 | @section /proc | |
3879 | ||
3880 | @section win32 | |
3881 | ||
3882 | @section shared libraries | |
3883 | ||
3884 | @section Native Conditionals | |
56caf160 | 3885 | @cindex native conditionals |
c906108c | 3886 | |
56caf160 EZ |
3887 | When @value{GDBN} is configured and compiled, various macros are |
3888 | defined or left undefined, to control compilation when the host and | |
3889 | target systems are the same. These macros should be defined (or left | |
3890 | undefined) in @file{nm-@var{system}.h}. | |
c906108c SS |
3891 | |
3892 | @table @code | |
c906108c | 3893 | @item ATTACH_DETACH |
56caf160 | 3894 | @findex ATTACH_DETACH |
25822942 | 3895 | If defined, then @value{GDBN} will include support for the @code{attach} and |
c906108c SS |
3896 | @code{detach} commands. |
3897 | ||
3898 | @item CHILD_PREPARE_TO_STORE | |
56caf160 | 3899 | @findex CHILD_PREPARE_TO_STORE |
c906108c SS |
3900 | If the machine stores all registers at once in the child process, then |
3901 | define this to ensure that all values are correct. This usually entails | |
3902 | a read from the child. | |
3903 | ||
3904 | [Note that this is incorrectly defined in @file{xm-@var{system}.h} files | |
3905 | currently.] | |
3906 | ||
3907 | @item FETCH_INFERIOR_REGISTERS | |
56caf160 | 3908 | @findex FETCH_INFERIOR_REGISTERS |
c906108c SS |
3909 | Define this if the native-dependent code will provide its own routines |
3910 | @code{fetch_inferior_registers} and @code{store_inferior_registers} in | |
56caf160 | 3911 | @file{@var{host}-nat.c}. If this symbol is @emph{not} defined, and |
c906108c SS |
3912 | @file{infptrace.c} is included in this configuration, the default |
3913 | routines in @file{infptrace.c} are used for these functions. | |
3914 | ||
3915 | @item FILES_INFO_HOOK | |
56caf160 | 3916 | @findex FILES_INFO_HOOK |
c906108c SS |
3917 | (Only defined for Convex.) |
3918 | ||
3919 | @item FP0_REGNUM | |
56caf160 | 3920 | @findex FP0_REGNUM |
c906108c SS |
3921 | This macro is normally defined to be the number of the first floating |
3922 | point register, if the machine has such registers. As such, it would | |
56caf160 | 3923 | appear only in target-specific code. However, @file{/proc} support uses this |
c906108c SS |
3924 | to decide whether floats are in use on this target. |
3925 | ||
3926 | @item GET_LONGJMP_TARGET | |
56caf160 | 3927 | @findex GET_LONGJMP_TARGET |
c906108c SS |
3928 | For most machines, this is a target-dependent parameter. On the |
3929 | DECstation and the Iris, this is a native-dependent parameter, since | |
56caf160 | 3930 | @file{setjmp.h} is needed to define it. |
c906108c | 3931 | |
56caf160 | 3932 | This macro determines the target PC address that @code{longjmp} will jump to, |
c906108c | 3933 | assuming that we have just stopped at a longjmp breakpoint. It takes a |
56caf160 | 3934 | @code{CORE_ADDR *} as argument, and stores the target PC value through this |
c906108c SS |
3935 | pointer. It examines the current state of the machine as needed. |
3936 | ||
9742079a EZ |
3937 | @item I386_USE_GENERIC_WATCHPOINTS |
3938 | An x86-based machine can define this to use the generic x86 watchpoint | |
3939 | support; see @ref{Algorithms, I386_USE_GENERIC_WATCHPOINTS}. | |
3940 | ||
c906108c | 3941 | @item KERNEL_U_ADDR |
56caf160 | 3942 | @findex KERNEL_U_ADDR |
c906108c | 3943 | Define this to the address of the @code{u} structure (the ``user |
25822942 | 3944 | struct'', also known as the ``u-page'') in kernel virtual memory. @value{GDBN} |
c906108c SS |
3945 | needs to know this so that it can subtract this address from absolute |
3946 | addresses in the upage, that are obtained via ptrace or from core files. | |
3947 | On systems that don't need this value, set it to zero. | |
3948 | ||
3949 | @item KERNEL_U_ADDR_BSD | |
56caf160 | 3950 | @findex KERNEL_U_ADDR_BSD |
25822942 | 3951 | Define this to cause @value{GDBN} to determine the address of @code{u} at |
c906108c SS |
3952 | runtime, by using Berkeley-style @code{nlist} on the kernel's image in |
3953 | the root directory. | |
3954 | ||
3955 | @item KERNEL_U_ADDR_HPUX | |
56caf160 | 3956 | @findex KERNEL_U_ADDR_HPUX |
25822942 | 3957 | Define this to cause @value{GDBN} to determine the address of @code{u} at |
c906108c SS |
3958 | runtime, by using HP-style @code{nlist} on the kernel's image in the |
3959 | root directory. | |
3960 | ||
3961 | @item ONE_PROCESS_WRITETEXT | |
56caf160 | 3962 | @findex ONE_PROCESS_WRITETEXT |
c906108c SS |
3963 | Define this to be able to, when a breakpoint insertion fails, warn the |
3964 | user that another process may be running with the same executable. | |
3965 | ||
56caf160 EZ |
3966 | @item PREPARE_TO_PROCEED (@var{select_it}) |
3967 | @findex PREPARE_TO_PROCEED | |
adf40b2e JM |
3968 | This (ugly) macro allows a native configuration to customize the way the |
3969 | @code{proceed} function in @file{infrun.c} deals with switching between | |
3970 | threads. | |
3971 | ||
3972 | In a multi-threaded task we may select another thread and then continue | |
3973 | or step. But if the old thread was stopped at a breakpoint, it will | |
3974 | immediately cause another breakpoint stop without any execution (i.e. it | |
25822942 | 3975 | will report a breakpoint hit incorrectly). So @value{GDBN} must step over it |
adf40b2e JM |
3976 | first. |
3977 | ||
3978 | If defined, @code{PREPARE_TO_PROCEED} should check the current thread | |
3979 | against the thread that reported the most recent event. If a step-over | |
3980 | is required, it returns TRUE. If @var{select_it} is non-zero, it should | |
3981 | reselect the old thread. | |
3982 | ||
c906108c | 3983 | @item PROC_NAME_FMT |
56caf160 | 3984 | @findex PROC_NAME_FMT |
c906108c SS |
3985 | Defines the format for the name of a @file{/proc} device. Should be |
3986 | defined in @file{nm.h} @emph{only} in order to override the default | |
3987 | definition in @file{procfs.c}. | |
3988 | ||
3989 | @item PTRACE_FP_BUG | |
56caf160 EZ |
3990 | @findex PTRACE_FP_BUG |
3991 | See @file{mach386-xdep.c}. | |
c906108c SS |
3992 | |
3993 | @item PTRACE_ARG3_TYPE | |
56caf160 | 3994 | @findex PTRACE_ARG3_TYPE |
c906108c SS |
3995 | The type of the third argument to the @code{ptrace} system call, if it |
3996 | exists and is different from @code{int}. | |
3997 | ||
3998 | @item REGISTER_U_ADDR | |
56caf160 | 3999 | @findex REGISTER_U_ADDR |
c906108c SS |
4000 | Defines the offset of the registers in the ``u area''. |
4001 | ||
4002 | @item SHELL_COMMAND_CONCAT | |
56caf160 | 4003 | @findex SHELL_COMMAND_CONCAT |
c906108c SS |
4004 | If defined, is a string to prefix on the shell command used to start the |
4005 | inferior. | |
4006 | ||
4007 | @item SHELL_FILE | |
56caf160 | 4008 | @findex SHELL_FILE |
c906108c SS |
4009 | If defined, this is the name of the shell to use to run the inferior. |
4010 | Defaults to @code{"/bin/sh"}. | |
4011 | ||
990f9fe3 | 4012 | @item SOLIB_ADD (@var{filename}, @var{from_tty}, @var{targ}, @var{readsyms}) |
56caf160 | 4013 | @findex SOLIB_ADD |
c906108c | 4014 | Define this to expand into an expression that will cause the symbols in |
990f9fe3 FF |
4015 | @var{filename} to be added to @value{GDBN}'s symbol table. If |
4016 | @var{readsyms} is zero symbols are not read but any necessary low level | |
4017 | processing for @var{filename} is still done. | |
c906108c SS |
4018 | |
4019 | @item SOLIB_CREATE_INFERIOR_HOOK | |
56caf160 | 4020 | @findex SOLIB_CREATE_INFERIOR_HOOK |
c906108c SS |
4021 | Define this to expand into any shared-library-relocation code that you |
4022 | want to be run just after the child process has been forked. | |
4023 | ||
4024 | @item START_INFERIOR_TRAPS_EXPECTED | |
56caf160 EZ |
4025 | @findex START_INFERIOR_TRAPS_EXPECTED |
4026 | When starting an inferior, @value{GDBN} normally expects to trap | |
4027 | twice; once when | |
c906108c SS |
4028 | the shell execs, and once when the program itself execs. If the actual |
4029 | number of traps is something other than 2, then define this macro to | |
4030 | expand into the number expected. | |
4031 | ||
4032 | @item SVR4_SHARED_LIBS | |
56caf160 | 4033 | @findex SVR4_SHARED_LIBS |
c906108c SS |
4034 | Define this to indicate that SVR4-style shared libraries are in use. |
4035 | ||
4036 | @item USE_PROC_FS | |
56caf160 | 4037 | @findex USE_PROC_FS |
c906108c | 4038 | This determines whether small routines in @file{*-tdep.c}, which |
56caf160 EZ |
4039 | translate register values between @value{GDBN}'s internal |
4040 | representation and the @file{/proc} representation, are compiled. | |
c906108c SS |
4041 | |
4042 | @item U_REGS_OFFSET | |
56caf160 | 4043 | @findex U_REGS_OFFSET |
c906108c SS |
4044 | This is the offset of the registers in the upage. It need only be |
4045 | defined if the generic ptrace register access routines in | |
4046 | @file{infptrace.c} are being used (that is, @file{infptrace.c} is | |
4047 | configured in, and @code{FETCH_INFERIOR_REGISTERS} is not defined). If | |
4048 | the default value from @file{infptrace.c} is good enough, leave it | |
4049 | undefined. | |
4050 | ||
4051 | The default value means that u.u_ar0 @emph{points to} the location of | |
4052 | the registers. I'm guessing that @code{#define U_REGS_OFFSET 0} means | |
56caf160 | 4053 | that @code{u.u_ar0} @emph{is} the location of the registers. |
c906108c SS |
4054 | |
4055 | @item CLEAR_SOLIB | |
56caf160 EZ |
4056 | @findex CLEAR_SOLIB |
4057 | See @file{objfiles.c}. | |
c906108c SS |
4058 | |
4059 | @item DEBUG_PTRACE | |
56caf160 EZ |
4060 | @findex DEBUG_PTRACE |
4061 | Define this to debug @code{ptrace} calls. | |
c906108c SS |
4062 | @end table |
4063 | ||
4064 | ||
4065 | @node Support Libraries | |
4066 | ||
4067 | @chapter Support Libraries | |
4068 | ||
4069 | @section BFD | |
56caf160 | 4070 | @cindex BFD library |
c906108c | 4071 | |
25822942 | 4072 | BFD provides support for @value{GDBN} in several ways: |
c906108c SS |
4073 | |
4074 | @table @emph | |
c906108c SS |
4075 | @item identifying executable and core files |
4076 | BFD will identify a variety of file types, including a.out, coff, and | |
4077 | several variants thereof, as well as several kinds of core files. | |
4078 | ||
4079 | @item access to sections of files | |
4080 | BFD parses the file headers to determine the names, virtual addresses, | |
4081 | sizes, and file locations of all the various named sections in files | |
56caf160 EZ |
4082 | (such as the text section or the data section). @value{GDBN} simply |
4083 | calls BFD to read or write section @var{x} at byte offset @var{y} for | |
4084 | length @var{z}. | |
c906108c SS |
4085 | |
4086 | @item specialized core file support | |
4087 | BFD provides routines to determine the failing command name stored in a | |
4088 | core file, the signal with which the program failed, and whether a core | |
56caf160 | 4089 | file matches (i.e.@: could be a core dump of) a particular executable |
c906108c SS |
4090 | file. |
4091 | ||
4092 | @item locating the symbol information | |
25822942 DB |
4093 | @value{GDBN} uses an internal interface of BFD to determine where to find the |
4094 | symbol information in an executable file or symbol-file. @value{GDBN} itself | |
c906108c | 4095 | handles the reading of symbols, since BFD does not ``understand'' debug |
25822942 | 4096 | symbols, but @value{GDBN} uses BFD's cached information to find the symbols, |
c906108c | 4097 | string table, etc. |
c906108c SS |
4098 | @end table |
4099 | ||
4100 | @section opcodes | |
56caf160 | 4101 | @cindex opcodes library |
c906108c | 4102 | |
25822942 | 4103 | The opcodes library provides @value{GDBN}'s disassembler. (It's a separate |
c906108c SS |
4104 | library because it's also used in binutils, for @file{objdump}). |
4105 | ||
4106 | @section readline | |
4107 | ||
4108 | @section mmalloc | |
4109 | ||
4110 | @section libiberty | |
4111 | ||
4112 | @section gnu-regex | |
56caf160 | 4113 | @cindex regular expressions library |
c906108c SS |
4114 | |
4115 | Regex conditionals. | |
4116 | ||
4117 | @table @code | |
c906108c SS |
4118 | @item C_ALLOCA |
4119 | ||
4120 | @item NFAILURES | |
4121 | ||
4122 | @item RE_NREGS | |
4123 | ||
4124 | @item SIGN_EXTEND_CHAR | |
4125 | ||
4126 | @item SWITCH_ENUM_BUG | |
4127 | ||
4128 | @item SYNTAX_TABLE | |
4129 | ||
4130 | @item Sword | |
4131 | ||
4132 | @item sparc | |
c906108c SS |
4133 | @end table |
4134 | ||
4135 | @section include | |
4136 | ||
4137 | @node Coding | |
4138 | ||
4139 | @chapter Coding | |
4140 | ||
4141 | This chapter covers topics that are lower-level than the major | |
25822942 | 4142 | algorithms of @value{GDBN}. |
c906108c SS |
4143 | |
4144 | @section Cleanups | |
56caf160 | 4145 | @cindex cleanups |
c906108c SS |
4146 | |
4147 | Cleanups are a structured way to deal with things that need to be done | |
4148 | later. When your code does something (like @code{malloc} some memory, | |
56caf160 | 4149 | or open a file) that needs to be undone later (e.g., free the memory or |
c906108c SS |
4150 | close the file), it can make a cleanup. The cleanup will be done at |
4151 | some future point: when the command is finished, when an error occurs, | |
4152 | or when your code decides it's time to do cleanups. | |
4153 | ||
4154 | You can also discard cleanups, that is, throw them away without doing | |
4155 | what they say. This is only done if you ask that it be done. | |
4156 | ||
4157 | Syntax: | |
4158 | ||
4159 | @table @code | |
c906108c SS |
4160 | @item struct cleanup *@var{old_chain}; |
4161 | Declare a variable which will hold a cleanup chain handle. | |
4162 | ||
56caf160 | 4163 | @findex make_cleanup |
c906108c SS |
4164 | @item @var{old_chain} = make_cleanup (@var{function}, @var{arg}); |
4165 | Make a cleanup which will cause @var{function} to be called with | |
4166 | @var{arg} (a @code{char *}) later. The result, @var{old_chain}, is a | |
4167 | handle that can be passed to @code{do_cleanups} or | |
4168 | @code{discard_cleanups} later. Unless you are going to call | |
4169 | @code{do_cleanups} or @code{discard_cleanups} yourself, you can ignore | |
4170 | the result from @code{make_cleanup}. | |
4171 | ||
56caf160 | 4172 | @findex do_cleanups |
c906108c SS |
4173 | @item do_cleanups (@var{old_chain}); |
4174 | Perform all cleanups done since @code{make_cleanup} returned | |
4175 | @var{old_chain}. E.g.: | |
56caf160 | 4176 | |
c906108c SS |
4177 | @example |
4178 | make_cleanup (a, 0); | |
4179 | old = make_cleanup (b, 0); | |
4180 | do_cleanups (old); | |
4181 | @end example | |
56caf160 | 4182 | |
c906108c SS |
4183 | @noindent |
4184 | will call @code{b()} but will not call @code{a()}. The cleanup that | |
4185 | calls @code{a()} will remain in the cleanup chain, and will be done | |
4186 | later unless otherwise discarded.@refill | |
4187 | ||
56caf160 | 4188 | @findex discard_cleanups |
c906108c SS |
4189 | @item discard_cleanups (@var{old_chain}); |
4190 | Same as @code{do_cleanups} except that it just removes the cleanups from | |
4191 | the chain and does not call the specified functions. | |
c906108c SS |
4192 | @end table |
4193 | ||
4194 | Some functions, e.g. @code{fputs_filtered()} or @code{error()}, specify | |
4195 | that they ``should not be called when cleanups are not in place''. This | |
4196 | means that any actions you need to reverse in the case of an error or | |
4197 | interruption must be on the cleanup chain before you call these | |
4198 | functions, since they might never return to your code (they | |
4199 | @samp{longjmp} instead). | |
4200 | ||
4201 | @section Wrapping Output Lines | |
56caf160 | 4202 | @cindex line wrap in output |
c906108c | 4203 | |
56caf160 | 4204 | @findex wrap_here |
c906108c SS |
4205 | Output that goes through @code{printf_filtered} or @code{fputs_filtered} |
4206 | or @code{fputs_demangled} needs only to have calls to @code{wrap_here} | |
4207 | added in places that would be good breaking points. The utility | |
4208 | routines will take care of actually wrapping if the line width is | |
4209 | exceeded. | |
4210 | ||
4211 | The argument to @code{wrap_here} is an indentation string which is | |
4212 | printed @emph{only} if the line breaks there. This argument is saved | |
4213 | away and used later. It must remain valid until the next call to | |
4214 | @code{wrap_here} or until a newline has been printed through the | |
4215 | @code{*_filtered} functions. Don't pass in a local variable and then | |
4216 | return! | |
4217 | ||
56caf160 | 4218 | It is usually best to call @code{wrap_here} after printing a comma or |
c906108c SS |
4219 | space. If you call it before printing a space, make sure that your |
4220 | indentation properly accounts for the leading space that will print if | |
4221 | the line wraps there. | |
4222 | ||
4223 | Any function or set of functions that produce filtered output must | |
4224 | finish by printing a newline, to flush the wrap buffer, before switching | |
56caf160 | 4225 | to unfiltered (@code{printf}) output. Symbol reading routines that |
c906108c SS |
4226 | print warnings are a good example. |
4227 | ||
25822942 | 4228 | @section @value{GDBN} Coding Standards |
56caf160 | 4229 | @cindex coding standards |
c906108c | 4230 | |
25822942 | 4231 | @value{GDBN} follows the GNU coding standards, as described in |
c906108c | 4232 | @file{etc/standards.texi}. This file is also available for anonymous |
af6c57ea AC |
4233 | FTP from GNU archive sites. @value{GDBN} takes a strict interpretation |
4234 | of the standard; in general, when the GNU standard recommends a practice | |
4235 | but does not require it, @value{GDBN} requires it. | |
c906108c | 4236 | |
56caf160 EZ |
4237 | @value{GDBN} follows an additional set of coding standards specific to |
4238 | @value{GDBN}, as described in the following sections. | |
c906108c | 4239 | |
af6c57ea AC |
4240 | |
4241 | @subsection ISO-C | |
4242 | ||
4243 | @value{GDBN} assumes an ISO-C compliant compiler. | |
4244 | ||
4245 | @value{GDBN} does not assume an ISO-C or POSIX compliant C library. | |
4246 | ||
4247 | ||
4248 | @subsection Memory Management | |
4249 | ||
4250 | @value{GDBN} does not use the functions @code{malloc}, @code{realloc}, | |
4251 | @code{calloc}, @code{free} and @code{asprintf}. | |
4252 | ||
4253 | @value{GDBN} uses the functions @code{xmalloc}, @code{xrealloc} and | |
4254 | @code{xcalloc} when allocating memory. Unlike @code{malloc} et.al.@: | |
4255 | these functions do not return when the memory pool is empty. Instead, | |
4256 | they unwind the stack using cleanups. These functions return | |
4257 | @code{NULL} when requested to allocate a chunk of memory of size zero. | |
4258 | ||
4259 | @emph{Pragmatics: By using these functions, the need to check every | |
4260 | memory allocation is removed. These functions provide portable | |
4261 | behavior.} | |
4262 | ||
4263 | @value{GDBN} does not use the function @code{free}. | |
4264 | ||
4265 | @value{GDBN} uses the function @code{xfree} to return memory to the | |
4266 | memory pool. Consistent with ISO-C, this function ignores a request to | |
4267 | free a @code{NULL} pointer. | |
4268 | ||
4269 | @emph{Pragmatics: On some systems @code{free} fails when passed a | |
4270 | @code{NULL} pointer.} | |
4271 | ||
4272 | @value{GDBN} can use the non-portable function @code{alloca} for the | |
4273 | allocation of small temporary values (such as strings). | |
4274 | ||
4275 | @emph{Pragmatics: This function is very non-portable. Some systems | |
4276 | restrict the memory being allocated to no more than a few kilobytes.} | |
4277 | ||
4278 | @value{GDBN} uses the string function @code{xstrdup} and the print | |
4279 | function @code{xasprintf}. | |
4280 | ||
4281 | @emph{Pragmatics: @code{asprintf} and @code{strdup} can fail. Print | |
4282 | functions such as @code{sprintf} are very prone to buffer overflow | |
4283 | errors.} | |
4284 | ||
4285 | ||
4286 | @subsection Compiler Warnings | |
56caf160 | 4287 | @cindex compiler warnings |
af6c57ea AC |
4288 | |
4289 | With few exceptions, developers should include the configuration option | |
4290 | @samp{--enable-gdb-build-warnings=,-Werror} when building @value{GDBN}. | |
4291 | The exceptions are listed in the file @file{gdb/MAINTAINERS}. | |
4292 | ||
4293 | This option causes @value{GDBN} (when built using GCC) to be compiled | |
4294 | with a carefully selected list of compiler warning flags. Any warnings | |
4295 | from those flags being treated as errors. | |
4296 | ||
4297 | The current list of warning flags includes: | |
4298 | ||
4299 | @table @samp | |
4300 | @item -Wimplicit | |
4301 | Since @value{GDBN} coding standard requires all functions to be declared | |
4302 | using a prototype, the flag has the side effect of ensuring that | |
4303 | prototyped functions are always visible with out resorting to | |
4304 | @samp{-Wstrict-prototypes}. | |
4305 | ||
4306 | @item -Wreturn-type | |
4307 | Such code often appears to work except on instruction set architectures | |
4308 | that use register windows. | |
4309 | ||
4310 | @item -Wcomment | |
4311 | ||
4312 | @item -Wtrigraphs | |
4313 | ||
4314 | @item -Wformat | |
4315 | Since @value{GDBN} uses the @code{format printf} attribute on all | |
4316 | @code{printf} like functions this checks not just @code{printf} calls | |
4317 | but also calls to functions such as @code{fprintf_unfiltered}. | |
4318 | ||
4319 | @item -Wparentheses | |
4320 | This warning includes uses of the assignment operator within an | |
4321 | @code{if} statement. | |
4322 | ||
4323 | @item -Wpointer-arith | |
4324 | ||
4325 | @item -Wuninitialized | |
4326 | @end table | |
4327 | ||
4328 | @emph{Pragmatics: Due to the way that @value{GDBN} is implemented most | |
4329 | functions have unused parameters. Consequently the warning | |
4330 | @samp{-Wunused-parameter} is precluded from the list. The macro | |
4331 | @code{ATTRIBUTE_UNUSED} is not used as it leads to false negatives --- | |
4332 | it is not an error to have @code{ATTRIBUTE_UNUSED} on a parameter that | |
4333 | is being used. The options @samp{-Wall} and @samp{-Wunused} are also | |
4334 | precluded because they both include @samp{-Wunused-parameter}.} | |
4335 | ||
4336 | @emph{Pragmatics: @value{GDBN} has not simply accepted the warnings | |
4337 | enabled by @samp{-Wall -Werror -W...}. Instead it is selecting warnings | |
4338 | when and where their benefits can be demonstrated.} | |
c906108c SS |
4339 | |
4340 | @subsection Formatting | |
4341 | ||
56caf160 | 4342 | @cindex source code formatting |
c906108c SS |
4343 | The standard GNU recommendations for formatting must be followed |
4344 | strictly. | |
4345 | ||
af6c57ea AC |
4346 | A function declaration should not have its name in column zero. A |
4347 | function definition should have its name in column zero. | |
4348 | ||
4349 | @example | |
4350 | /* Declaration */ | |
4351 | static void foo (void); | |
4352 | /* Definition */ | |
4353 | void | |
4354 | foo (void) | |
4355 | @{ | |
4356 | @} | |
4357 | @end example | |
4358 | ||
4359 | @emph{Pragmatics: This simplifies scripting. Function definitions can | |
4360 | be found using @samp{^function-name}.} | |
c906108c | 4361 | |
af6c57ea AC |
4362 | There must be a space between a function or macro name and the opening |
4363 | parenthesis of its argument list (except for macro definitions, as | |
4364 | required by C). There must not be a space after an open paren/bracket | |
4365 | or before a close paren/bracket. | |
c906108c SS |
4366 | |
4367 | While additional whitespace is generally helpful for reading, do not use | |
4368 | more than one blank line to separate blocks, and avoid adding whitespace | |
af6c57ea AC |
4369 | after the end of a program line (as of 1/99, some 600 lines had |
4370 | whitespace after the semicolon). Excess whitespace causes difficulties | |
4371 | for @code{diff} and @code{patch} utilities. | |
4372 | ||
4373 | Pointers are declared using the traditional K&R C style: | |
4374 | ||
4375 | @example | |
4376 | void *foo; | |
4377 | @end example | |
4378 | ||
4379 | @noindent | |
4380 | and not: | |
4381 | ||
4382 | @example | |
4383 | void * foo; | |
4384 | void* foo; | |
4385 | @end example | |
c906108c SS |
4386 | |
4387 | @subsection Comments | |
4388 | ||
56caf160 | 4389 | @cindex comment formatting |
c906108c SS |
4390 | The standard GNU requirements on comments must be followed strictly. |
4391 | ||
af6c57ea AC |
4392 | Block comments must appear in the following form, with no @code{/*}- or |
4393 | @code{*/}-only lines, and no leading @code{*}: | |
c906108c | 4394 | |
56caf160 | 4395 | @example |
c906108c SS |
4396 | /* Wait for control to return from inferior to debugger. If inferior |
4397 | gets a signal, we may decide to start it up again instead of | |
4398 | returning. That is why there is a loop in this function. When | |
4399 | this function actually returns it means the inferior should be left | |
25822942 | 4400 | stopped and @value{GDBN} should read more commands. */ |
c906108c SS |
4401 | @end example |
4402 | ||
4403 | (Note that this format is encouraged by Emacs; tabbing for a multi-line | |
56caf160 | 4404 | comment works correctly, and @kbd{M-q} fills the block consistently.) |
c906108c SS |
4405 | |
4406 | Put a blank line between the block comments preceding function or | |
4407 | variable definitions, and the definition itself. | |
4408 | ||
4409 | In general, put function-body comments on lines by themselves, rather | |
4410 | than trying to fit them into the 20 characters left at the end of a | |
4411 | line, since either the comment or the code will inevitably get longer | |
4412 | than will fit, and then somebody will have to move it anyhow. | |
4413 | ||
4414 | @subsection C Usage | |
4415 | ||
56caf160 | 4416 | @cindex C data types |
c906108c SS |
4417 | Code must not depend on the sizes of C data types, the format of the |
4418 | host's floating point numbers, the alignment of anything, or the order | |
4419 | of evaluation of expressions. | |
4420 | ||
56caf160 | 4421 | @cindex function usage |
c906108c | 4422 | Use functions freely. There are only a handful of compute-bound areas |
56caf160 EZ |
4423 | in @value{GDBN} that might be affected by the overhead of a function |
4424 | call, mainly in symbol reading. Most of @value{GDBN}'s performance is | |
4425 | limited by the target interface (whether serial line or system call). | |
c906108c SS |
4426 | |
4427 | However, use functions with moderation. A thousand one-line functions | |
4428 | are just as hard to understand as a single thousand-line function. | |
4429 | ||
af6c57ea | 4430 | @emph{Macros are bad, M'kay.} |
9e678452 CF |
4431 | (But if you have to use a macro, make sure that the macro arguments are |
4432 | protected with parentheses.) | |
af6c57ea AC |
4433 | |
4434 | @cindex types | |
c906108c | 4435 | |
af6c57ea AC |
4436 | Declarations like @samp{struct foo *} should be used in preference to |
4437 | declarations like @samp{typedef struct foo @{ @dots{} @} *foo_ptr}. | |
4438 | ||
4439 | ||
4440 | @subsection Function Prototypes | |
56caf160 | 4441 | @cindex function prototypes |
af6c57ea AC |
4442 | |
4443 | Prototypes must be used when both @emph{declaring} and @emph{defining} | |
4444 | a function. Prototypes for @value{GDBN} functions must include both the | |
4445 | argument type and name, with the name matching that used in the actual | |
4446 | function definition. | |
c906108c | 4447 | |
53a5351d JM |
4448 | All external functions should have a declaration in a header file that |
4449 | callers include, except for @code{_initialize_*} functions, which must | |
4450 | be external so that @file{init.c} construction works, but shouldn't be | |
4451 | visible to random source files. | |
c906108c | 4452 | |
af6c57ea AC |
4453 | Where a source file needs a forward declaration of a static function, |
4454 | that declaration must appear in a block near the top of the source file. | |
4455 | ||
4456 | ||
4457 | @subsection Internal Error Recovery | |
4458 | ||
4459 | During its execution, @value{GDBN} can encounter two types of errors. | |
4460 | User errors and internal errors. User errors include not only a user | |
4461 | entering an incorrect command but also problems arising from corrupt | |
4462 | object files and system errors when interacting with the target. | |
4463 | Internal errors include situtations where @value{GDBN} has detected, at | |
4464 | run time, a corrupt or erroneous situtation. | |
4465 | ||
4466 | When reporting an internal error, @value{GDBN} uses | |
4467 | @code{internal_error} and @code{gdb_assert}. | |
4468 | ||
4469 | @value{GDBN} must not call @code{abort} or @code{assert}. | |
4470 | ||
4471 | @emph{Pragmatics: There is no @code{internal_warning} function. Either | |
4472 | the code detected a user error, recovered from it and issued a | |
4473 | @code{warning} or the code failed to correctly recover from the user | |
4474 | error and issued an @code{internal_error}.} | |
4475 | ||
4476 | @subsection File Names | |
4477 | ||
4478 | Any file used when building the core of @value{GDBN} must be in lower | |
4479 | case. Any file used when building the core of @value{GDBN} must be 8.3 | |
4480 | unique. These requirements apply to both source and generated files. | |
4481 | ||
4482 | @emph{Pragmatics: The core of @value{GDBN} must be buildable on many | |
4483 | platforms including DJGPP and MacOS/HFS. Every time an unfriendly file | |
4484 | is introduced to the build process both @file{Makefile.in} and | |
4485 | @file{configure.in} need to be modified accordingly. Compare the | |
4486 | convoluted conversion process needed to transform @file{COPYING} into | |
4487 | @file{copying.c} with the conversion needed to transform | |
4488 | @file{version.in} into @file{version.c}.} | |
4489 | ||
4490 | Any file non 8.3 compliant file (that is not used when building the core | |
4491 | of @value{GDBN}) must be added to @file{gdb/config/djgpp/fnchange.lst}. | |
4492 | ||
4493 | @emph{Pragmatics: This is clearly a compromise.} | |
4494 | ||
4495 | When @value{GDBN} has a local version of a system header file (ex | |
4496 | @file{string.h}) the file name based on the POSIX header prefixed with | |
4497 | @file{gdb_} (@file{gdb_string.h}). | |
4498 | ||
4499 | For other files @samp{-} is used as the separator. | |
4500 | ||
4501 | ||
4502 | @subsection Include Files | |
4503 | ||
4504 | All @file{.c} files should include @file{defs.h} first. | |
4505 | ||
4506 | All @file{.c} files should explicitly include the headers for any | |
4507 | declarations they refer to. They should not rely on files being | |
4508 | included indirectly. | |
4509 | ||
4510 | With the exception of the global definitions supplied by @file{defs.h}, | |
4511 | a header file should explictily include the header declaring any | |
4512 | @code{typedefs} et.al.@: it refers to. | |
4513 | ||
4514 | @code{extern} declarations should never appear in @code{.c} files. | |
4515 | ||
4516 | All include files should be wrapped in: | |
4517 | ||
4518 | @example | |
4519 | #ifndef INCLUDE_FILE_NAME_H | |
4520 | #define INCLUDE_FILE_NAME_H | |
4521 | header body | |
4522 | #endif | |
4523 | @end example | |
4524 | ||
c906108c | 4525 | |
dab11f21 | 4526 | @subsection Clean Design and Portable Implementation |
c906108c | 4527 | |
56caf160 | 4528 | @cindex design |
c906108c | 4529 | In addition to getting the syntax right, there's the little question of |
25822942 | 4530 | semantics. Some things are done in certain ways in @value{GDBN} because long |
c906108c SS |
4531 | experience has shown that the more obvious ways caused various kinds of |
4532 | trouble. | |
4533 | ||
56caf160 | 4534 | @cindex assumptions about targets |
c906108c SS |
4535 | You can't assume the byte order of anything that comes from a target |
4536 | (including @var{value}s, object files, and instructions). Such things | |
56caf160 EZ |
4537 | must be byte-swapped using @code{SWAP_TARGET_AND_HOST} in |
4538 | @value{GDBN}, or one of the swap routines defined in @file{bfd.h}, | |
4539 | such as @code{bfd_get_32}. | |
c906108c SS |
4540 | |
4541 | You can't assume that you know what interface is being used to talk to | |
4542 | the target system. All references to the target must go through the | |
4543 | current @code{target_ops} vector. | |
4544 | ||
4545 | You can't assume that the host and target machines are the same machine | |
4546 | (except in the ``native'' support modules). In particular, you can't | |
4547 | assume that the target machine's header files will be available on the | |
4548 | host machine. Target code must bring along its own header files -- | |
4549 | written from scratch or explicitly donated by their owner, to avoid | |
4550 | copyright problems. | |
4551 | ||
56caf160 | 4552 | @cindex portability |
c906108c SS |
4553 | Insertion of new @code{#ifdef}'s will be frowned upon. It's much better |
4554 | to write the code portably than to conditionalize it for various | |
4555 | systems. | |
4556 | ||
56caf160 | 4557 | @cindex system dependencies |
c906108c SS |
4558 | New @code{#ifdef}'s which test for specific compilers or manufacturers |
4559 | or operating systems are unacceptable. All @code{#ifdef}'s should test | |
4560 | for features. The information about which configurations contain which | |
4561 | features should be segregated into the configuration files. Experience | |
4562 | has proven far too often that a feature unique to one particular system | |
4563 | often creeps into other systems; and that a conditional based on some | |
4564 | predefined macro for your current system will become worthless over | |
4565 | time, as new versions of your system come out that behave differently | |
4566 | with regard to this feature. | |
4567 | ||
4568 | Adding code that handles specific architectures, operating systems, | |
af6c57ea | 4569 | target interfaces, or hosts, is not acceptable in generic code. |
c906108c | 4570 | |
dab11f21 EZ |
4571 | @cindex portable file name handling |
4572 | @cindex file names, portability | |
4573 | One particularly notorious area where system dependencies tend to | |
4574 | creep in is handling of file names. The mainline @value{GDBN} code | |
4575 | assumes Posix semantics of file names: absolute file names begin with | |
4576 | a forward slash @file{/}, slashes are used to separate leading | |
4577 | directories, case-sensitive file names. These assumptions are not | |
4578 | necessarily true on non-Posix systems such as MS-Windows. To avoid | |
4579 | system-dependent code where you need to take apart or construct a file | |
4580 | name, use the following portable macros: | |
4581 | ||
4582 | @table @code | |
4583 | @findex HAVE_DOS_BASED_FILE_SYSTEM | |
4584 | @item HAVE_DOS_BASED_FILE_SYSTEM | |
4585 | This preprocessing symbol is defined to a non-zero value on hosts | |
4586 | whose filesystems belong to the MS-DOS/MS-Windows family. Use this | |
4587 | symbol to write conditional code which should only be compiled for | |
4588 | such hosts. | |
4589 | ||
4590 | @findex IS_DIR_SEPARATOR | |
4591 | @item IS_DIR_SEPARATOR (@var{c} | |
4592 | Evaluates to a non-zero value if @var{c} is a directory separator | |
4593 | character. On Unix and GNU/Linux systems, only a slash @file{/} is | |
4594 | such a character, but on Windows, both @file{/} and @file{\} will | |
4595 | pass. | |
4596 | ||
4597 | @findex IS_ABSOLUTE_PATH | |
4598 | @item IS_ABSOLUTE_PATH (@var{file}) | |
4599 | Evaluates to a non-zero value if @var{file} is an absolute file name. | |
4600 | For Unix and GNU/Linux hosts, a name which begins with a slash | |
4601 | @file{/} is absolute. On DOS and Windows, @file{d:/foo} and | |
4602 | @file{x:\bar} are also absolute file names. | |
4603 | ||
4604 | @findex FILENAME_CMP | |
4605 | @item FILENAME_CMP (@var{f1}, @var{f2}) | |
4606 | Calls a function which compares file names @var{f1} and @var{f2} as | |
4607 | appropriate for the underlying host filesystem. For Posix systems, | |
4608 | this simply calls @code{strcmp}; on case-insensitive filesystems it | |
4609 | will call @code{strcasecmp} instead. | |
4610 | ||
4611 | @findex DIRNAME_SEPARATOR | |
4612 | @item DIRNAME_SEPARATOR | |
4613 | Evaluates to a character which separates directories in | |
4614 | @code{PATH}-style lists, typically held in environment variables. | |
4615 | This character is @samp{:} on Unix, @samp{;} on DOS and Windows. | |
4616 | ||
4617 | @findex SLASH_STRING | |
4618 | @item SLASH_STRING | |
4619 | This evaluates to a constant string you should use to produce an | |
4620 | absolute filename from leading directories and the file's basename. | |
4621 | @code{SLASH_STRING} is @code{"/"} on most systems, but might be | |
4622 | @code{"\\"} for some Windows-based ports. | |
4623 | @end table | |
4624 | ||
4625 | In addition to using these macros, be sure to use portable library | |
4626 | functions whenever possible. For example, to extract a directory or a | |
4627 | basename part from a file name, use the @code{dirname} and | |
4628 | @code{basename} library functions (available in @code{libiberty} for | |
4629 | platforms which don't provide them), instead of searching for a slash | |
4630 | with @code{strrchr}. | |
4631 | ||
25822942 DB |
4632 | Another way to generalize @value{GDBN} along a particular interface is with an |
4633 | attribute struct. For example, @value{GDBN} has been generalized to handle | |
56caf160 EZ |
4634 | multiple kinds of remote interfaces---not by @code{#ifdef}s everywhere, but |
4635 | by defining the @code{target_ops} structure and having a current target (as | |
c906108c SS |
4636 | well as a stack of targets below it, for memory references). Whenever |
4637 | something needs to be done that depends on which remote interface we are | |
56caf160 EZ |
4638 | using, a flag in the current target_ops structure is tested (e.g., |
4639 | @code{target_has_stack}), or a function is called through a pointer in the | |
c906108c | 4640 | current target_ops structure. In this way, when a new remote interface |
56caf160 | 4641 | is added, only one module needs to be touched---the one that actually |
c906108c SS |
4642 | implements the new remote interface. Other examples of |
4643 | attribute-structs are BFD access to multiple kinds of object file | |
25822942 | 4644 | formats, or @value{GDBN}'s access to multiple source languages. |
c906108c | 4645 | |
56caf160 EZ |
4646 | Please avoid duplicating code. For example, in @value{GDBN} 3.x all |
4647 | the code interfacing between @code{ptrace} and the rest of | |
4648 | @value{GDBN} was duplicated in @file{*-dep.c}, and so changing | |
4649 | something was very painful. In @value{GDBN} 4.x, these have all been | |
4650 | consolidated into @file{infptrace.c}. @file{infptrace.c} can deal | |
4651 | with variations between systems the same way any system-independent | |
4652 | file would (hooks, @code{#if defined}, etc.), and machines which are | |
4653 | radically different don't need to use @file{infptrace.c} at all. | |
c906108c | 4654 | |
af6c57ea AC |
4655 | All debugging code must be controllable using the @samp{set debug |
4656 | @var{module}} command. Do not use @code{printf} to print trace | |
4657 | messages. Use @code{fprintf_unfiltered(gdb_stdlog, ...}. Do not use | |
4658 | @code{#ifdef DEBUG}. | |
4659 | ||
c906108c | 4660 | |
8487521e | 4661 | @node Porting GDB |
c906108c | 4662 | |
25822942 | 4663 | @chapter Porting @value{GDBN} |
56caf160 | 4664 | @cindex porting to new machines |
c906108c | 4665 | |
56caf160 EZ |
4666 | Most of the work in making @value{GDBN} compile on a new machine is in |
4667 | specifying the configuration of the machine. This is done in a | |
4668 | dizzying variety of header files and configuration scripts, which we | |
4669 | hope to make more sensible soon. Let's say your new host is called an | |
4670 | @var{xyz} (e.g., @samp{sun4}), and its full three-part configuration | |
4671 | name is @code{@var{arch}-@var{xvend}-@var{xos}} (e.g., | |
4672 | @samp{sparc-sun-sunos4}). In particular: | |
c906108c | 4673 | |
56caf160 EZ |
4674 | @itemize @bullet |
4675 | @item | |
c906108c SS |
4676 | In the top level directory, edit @file{config.sub} and add @var{arch}, |
4677 | @var{xvend}, and @var{xos} to the lists of supported architectures, | |
4678 | vendors, and operating systems near the bottom of the file. Also, add | |
4679 | @var{xyz} as an alias that maps to | |
4680 | @code{@var{arch}-@var{xvend}-@var{xos}}. You can test your changes by | |
4681 | running | |
4682 | ||
4683 | @example | |
4684 | ./config.sub @var{xyz} | |
4685 | @end example | |
56caf160 | 4686 | |
c906108c SS |
4687 | @noindent |
4688 | and | |
56caf160 | 4689 | |
c906108c SS |
4690 | @example |
4691 | ./config.sub @code{@var{arch}-@var{xvend}-@var{xos}} | |
4692 | @end example | |
56caf160 | 4693 | |
c906108c SS |
4694 | @noindent |
4695 | which should both respond with @code{@var{arch}-@var{xvend}-@var{xos}} | |
4696 | and no error messages. | |
4697 | ||
56caf160 | 4698 | @noindent |
c906108c SS |
4699 | You need to port BFD, if that hasn't been done already. Porting BFD is |
4700 | beyond the scope of this manual. | |
4701 | ||
56caf160 | 4702 | @item |
25822942 | 4703 | To configure @value{GDBN} itself, edit @file{gdb/configure.host} to recognize |
c906108c SS |
4704 | your system and set @code{gdb_host} to @var{xyz}, and (unless your |
4705 | desired target is already available) also edit @file{gdb/configure.tgt}, | |
4706 | setting @code{gdb_target} to something appropriate (for instance, | |
4707 | @var{xyz}). | |
4708 | ||
56caf160 | 4709 | @item |
25822942 | 4710 | Finally, you'll need to specify and define @value{GDBN}'s host-, native-, and |
c906108c SS |
4711 | target-dependent @file{.h} and @file{.c} files used for your |
4712 | configuration. | |
56caf160 | 4713 | @end itemize |
c906108c | 4714 | |
25822942 | 4715 | @section Configuring @value{GDBN} for Release |
c906108c | 4716 | |
56caf160 EZ |
4717 | @cindex preparing a release |
4718 | @cindex making a distribution tarball | |
c906108c SS |
4719 | From the top level directory (containing @file{gdb}, @file{bfd}, |
4720 | @file{libiberty}, and so on): | |
56caf160 | 4721 | |
c906108c SS |
4722 | @example |
4723 | make -f Makefile.in gdb.tar.gz | |
4724 | @end example | |
4725 | ||
56caf160 | 4726 | @noindent |
c906108c SS |
4727 | This will properly configure, clean, rebuild any files that are |
4728 | distributed pre-built (e.g. @file{c-exp.tab.c} or @file{refcard.ps}), | |
4729 | and will then make a tarfile. (If the top level directory has already | |
4730 | been configured, you can just do @code{make gdb.tar.gz} instead.) | |
4731 | ||
4732 | This procedure requires: | |
56caf160 | 4733 | |
c906108c | 4734 | @itemize @bullet |
56caf160 EZ |
4735 | |
4736 | @item | |
4737 | symbolic links; | |
4738 | ||
4739 | @item | |
4740 | @code{makeinfo} (texinfo2 level); | |
4741 | ||
4742 | @item | |
4743 | @TeX{}; | |
4744 | ||
4745 | @item | |
4746 | @code{dvips}; | |
4747 | ||
4748 | @item | |
4749 | @code{yacc} or @code{bison}. | |
c906108c | 4750 | @end itemize |
56caf160 | 4751 | |
c906108c SS |
4752 | @noindent |
4753 | @dots{} and the usual slew of utilities (@code{sed}, @code{tar}, etc.). | |
4754 | ||
4755 | @subheading TEMPORARY RELEASE PROCEDURE FOR DOCUMENTATION | |
4756 | ||
4757 | @file{gdb.texinfo} is currently marked up using the texinfo-2 macros, | |
4758 | which are not yet a default for anything (but we have to start using | |
4759 | them sometime). | |
4760 | ||
4761 | For making paper, the only thing this implies is the right generation of | |
4762 | @file{texinfo.tex} needs to be included in the distribution. | |
4763 | ||
4764 | For making info files, however, rather than duplicating the texinfo2 | |
4765 | distribution, generate @file{gdb-all.texinfo} locally, and include the | |
4766 | files @file{gdb.info*} in the distribution. Note the plural; | |
4767 | @code{makeinfo} will split the document into one overall file and five | |
4768 | or so included files. | |
4769 | ||
085dd6e6 JM |
4770 | @node Testsuite |
4771 | ||
4772 | @chapter Testsuite | |
56caf160 | 4773 | @cindex test suite |
085dd6e6 | 4774 | |
56caf160 EZ |
4775 | The testsuite is an important component of the @value{GDBN} package. |
4776 | While it is always worthwhile to encourage user testing, in practice | |
4777 | this is rarely sufficient; users typically use only a small subset of | |
4778 | the available commands, and it has proven all too common for a change | |
4779 | to cause a significant regression that went unnoticed for some time. | |
085dd6e6 | 4780 | |
56caf160 EZ |
4781 | The @value{GDBN} testsuite uses the DejaGNU testing framework. |
4782 | DejaGNU is built using @code{Tcl} and @code{expect}. The tests | |
4783 | themselves are calls to various @code{Tcl} procs; the framework runs all the | |
4784 | procs and summarizes the passes and fails. | |
085dd6e6 JM |
4785 | |
4786 | @section Using the Testsuite | |
4787 | ||
56caf160 | 4788 | @cindex running the test suite |
25822942 | 4789 | To run the testsuite, simply go to the @value{GDBN} object directory (or to the |
085dd6e6 JM |
4790 | testsuite's objdir) and type @code{make check}. This just sets up some |
4791 | environment variables and invokes DejaGNU's @code{runtest} script. While | |
4792 | the testsuite is running, you'll get mentions of which test file is in use, | |
4793 | and a mention of any unexpected passes or fails. When the testsuite is | |
4794 | finished, you'll get a summary that looks like this: | |
56caf160 | 4795 | |
085dd6e6 JM |
4796 | @example |
4797 | === gdb Summary === | |
4798 | ||
4799 | # of expected passes 6016 | |
4800 | # of unexpected failures 58 | |
4801 | # of unexpected successes 5 | |
4802 | # of expected failures 183 | |
4803 | # of unresolved testcases 3 | |
4804 | # of untested testcases 5 | |
4805 | @end example | |
56caf160 | 4806 | |
085dd6e6 JM |
4807 | The ideal test run consists of expected passes only; however, reality |
4808 | conspires to keep us from this ideal. Unexpected failures indicate | |
56caf160 EZ |
4809 | real problems, whether in @value{GDBN} or in the testsuite. Expected |
4810 | failures are still failures, but ones which have been decided are too | |
4811 | hard to deal with at the time; for instance, a test case might work | |
4812 | everywhere except on AIX, and there is no prospect of the AIX case | |
4813 | being fixed in the near future. Expected failures should not be added | |
4814 | lightly, since you may be masking serious bugs in @value{GDBN}. | |
4815 | Unexpected successes are expected fails that are passing for some | |
4816 | reason, while unresolved and untested cases often indicate some minor | |
4817 | catastrophe, such as the compiler being unable to deal with a test | |
4818 | program. | |
4819 | ||
4820 | When making any significant change to @value{GDBN}, you should run the | |
4821 | testsuite before and after the change, to confirm that there are no | |
4822 | regressions. Note that truly complete testing would require that you | |
4823 | run the testsuite with all supported configurations and a variety of | |
4824 | compilers; however this is more than really necessary. In many cases | |
4825 | testing with a single configuration is sufficient. Other useful | |
4826 | options are to test one big-endian (Sparc) and one little-endian (x86) | |
4827 | host, a cross config with a builtin simulator (powerpc-eabi, | |
4828 | mips-elf), or a 64-bit host (Alpha). | |
4829 | ||
4830 | If you add new functionality to @value{GDBN}, please consider adding | |
4831 | tests for it as well; this way future @value{GDBN} hackers can detect | |
4832 | and fix their changes that break the functionality you added. | |
4833 | Similarly, if you fix a bug that was not previously reported as a test | |
4834 | failure, please add a test case for it. Some cases are extremely | |
4835 | difficult to test, such as code that handles host OS failures or bugs | |
4836 | in particular versions of compilers, and it's OK not to try to write | |
4837 | tests for all of those. | |
085dd6e6 JM |
4838 | |
4839 | @section Testsuite Organization | |
4840 | ||
56caf160 | 4841 | @cindex test suite organization |
085dd6e6 JM |
4842 | The testsuite is entirely contained in @file{gdb/testsuite}. While the |
4843 | testsuite includes some makefiles and configury, these are very minimal, | |
4844 | and used for little besides cleaning up, since the tests themselves | |
25822942 | 4845 | handle the compilation of the programs that @value{GDBN} will run. The file |
085dd6e6 | 4846 | @file{testsuite/lib/gdb.exp} contains common utility procs useful for |
25822942 | 4847 | all @value{GDBN} tests, while the directory @file{testsuite/config} contains |
085dd6e6 JM |
4848 | configuration-specific files, typically used for special-purpose |
4849 | definitions of procs like @code{gdb_load} and @code{gdb_start}. | |
4850 | ||
4851 | The tests themselves are to be found in @file{testsuite/gdb.*} and | |
4852 | subdirectories of those. The names of the test files must always end | |
4853 | with @file{.exp}. DejaGNU collects the test files by wildcarding | |
4854 | in the test directories, so both subdirectories and individual files | |
4855 | get chosen and run in alphabetical order. | |
4856 | ||
4857 | The following table lists the main types of subdirectories and what they | |
4858 | are for. Since DejaGNU finds test files no matter where they are | |
4859 | located, and since each test file sets up its own compilation and | |
4860 | execution environment, this organization is simply for convenience and | |
4861 | intelligibility. | |
4862 | ||
56caf160 | 4863 | @table @file |
085dd6e6 | 4864 | @item gdb.base |
085dd6e6 | 4865 | This is the base testsuite. The tests in it should apply to all |
25822942 | 4866 | configurations of @value{GDBN} (but generic native-only tests may live here). |
085dd6e6 | 4867 | The test programs should be in the subset of C that is valid K&R, |
56caf160 | 4868 | ANSI/ISO, and C++ (@code{#ifdef}s are allowed if necessary, for instance |
085dd6e6 JM |
4869 | for prototypes). |
4870 | ||
4871 | @item gdb.@var{lang} | |
56caf160 | 4872 | Language-specific tests for any language @var{lang} besides C. Examples are |
085dd6e6 JM |
4873 | @file{gdb.c++} and @file{gdb.java}. |
4874 | ||
4875 | @item gdb.@var{platform} | |
085dd6e6 JM |
4876 | Non-portable tests. The tests are specific to a specific configuration |
4877 | (host or target), such as HP-UX or eCos. Example is @file{gdb.hp}, for | |
4878 | HP-UX. | |
4879 | ||
4880 | @item gdb.@var{compiler} | |
085dd6e6 JM |
4881 | Tests specific to a particular compiler. As of this writing (June |
4882 | 1999), there aren't currently any groups of tests in this category that | |
4883 | couldn't just as sensibly be made platform-specific, but one could | |
56caf160 EZ |
4884 | imagine a @file{gdb.gcc}, for tests of @value{GDBN}'s handling of GCC |
4885 | extensions. | |
085dd6e6 JM |
4886 | |
4887 | @item gdb.@var{subsystem} | |
25822942 | 4888 | Tests that exercise a specific @value{GDBN} subsystem in more depth. For |
085dd6e6 JM |
4889 | instance, @file{gdb.disasm} exercises various disassemblers, while |
4890 | @file{gdb.stabs} tests pathways through the stabs symbol reader. | |
085dd6e6 JM |
4891 | @end table |
4892 | ||
4893 | @section Writing Tests | |
56caf160 | 4894 | @cindex writing tests |
085dd6e6 | 4895 | |
25822942 | 4896 | In many areas, the @value{GDBN} tests are already quite comprehensive; you |
085dd6e6 JM |
4897 | should be able to copy existing tests to handle new cases. |
4898 | ||
4899 | You should try to use @code{gdb_test} whenever possible, since it | |
4900 | includes cases to handle all the unexpected errors that might happen. | |
4901 | However, it doesn't cost anything to add new test procedures; for | |
4902 | instance, @file{gdb.base/exprs.exp} defines a @code{test_expr} that | |
4903 | calls @code{gdb_test} multiple times. | |
4904 | ||
4905 | Only use @code{send_gdb} and @code{gdb_expect} when absolutely | |
25822942 | 4906 | necessary, such as when @value{GDBN} has several valid responses to a command. |
085dd6e6 JM |
4907 | |
4908 | The source language programs do @emph{not} need to be in a consistent | |
25822942 | 4909 | style. Since @value{GDBN} is used to debug programs written in many different |
085dd6e6 | 4910 | styles, it's worth having a mix of styles in the testsuite; for |
25822942 | 4911 | instance, some @value{GDBN} bugs involving the display of source lines would |
085dd6e6 JM |
4912 | never manifest themselves if the programs used GNU coding style |
4913 | uniformly. | |
4914 | ||
c906108c SS |
4915 | @node Hints |
4916 | ||
4917 | @chapter Hints | |
4918 | ||
4919 | Check the @file{README} file, it often has useful information that does not | |
4920 | appear anywhere else in the directory. | |
4921 | ||
4922 | @menu | |
25822942 | 4923 | * Getting Started:: Getting started working on @value{GDBN} |
33e16fad | 4924 | * Debugging GDB:: Debugging @value{GDBN} with itself |
c906108c SS |
4925 | @end menu |
4926 | ||
4927 | @node Getting Started,,, Hints | |
4928 | ||
4929 | @section Getting Started | |
4930 | ||
25822942 | 4931 | @value{GDBN} is a large and complicated program, and if you first starting to |
c906108c SS |
4932 | work on it, it can be hard to know where to start. Fortunately, if you |
4933 | know how to go about it, there are ways to figure out what is going on. | |
4934 | ||
25822942 DB |
4935 | This manual, the @value{GDBN} Internals manual, has information which applies |
4936 | generally to many parts of @value{GDBN}. | |
c906108c SS |
4937 | |
4938 | Information about particular functions or data structures are located in | |
4939 | comments with those functions or data structures. If you run across a | |
4940 | function or a global variable which does not have a comment correctly | |
25822942 | 4941 | explaining what is does, this can be thought of as a bug in @value{GDBN}; feel |
c906108c SS |
4942 | free to submit a bug report, with a suggested comment if you can figure |
4943 | out what the comment should say. If you find a comment which is | |
4944 | actually wrong, be especially sure to report that. | |
4945 | ||
4946 | Comments explaining the function of macros defined in host, target, or | |
4947 | native dependent files can be in several places. Sometimes they are | |
4948 | repeated every place the macro is defined. Sometimes they are where the | |
4949 | macro is used. Sometimes there is a header file which supplies a | |
4950 | default definition of the macro, and the comment is there. This manual | |
4951 | also documents all the available macros. | |
4952 | @c (@pxref{Host Conditionals}, @pxref{Target | |
4953 | @c Conditionals}, @pxref{Native Conditionals}, and @pxref{Obsolete | |
4954 | @c Conditionals}) | |
4955 | ||
56caf160 EZ |
4956 | Start with the header files. Once you have some idea of how |
4957 | @value{GDBN}'s internal symbol tables are stored (see @file{symtab.h}, | |
4958 | @file{gdbtypes.h}), you will find it much easier to understand the | |
4959 | code which uses and creates those symbol tables. | |
c906108c SS |
4960 | |
4961 | You may wish to process the information you are getting somehow, to | |
4962 | enhance your understanding of it. Summarize it, translate it to another | |
25822942 | 4963 | language, add some (perhaps trivial or non-useful) feature to @value{GDBN}, use |
c906108c SS |
4964 | the code to predict what a test case would do and write the test case |
4965 | and verify your prediction, etc. If you are reading code and your eyes | |
4966 | are starting to glaze over, this is a sign you need to use a more active | |
4967 | approach. | |
4968 | ||
25822942 | 4969 | Once you have a part of @value{GDBN} to start with, you can find more |
c906108c SS |
4970 | specifically the part you are looking for by stepping through each |
4971 | function with the @code{next} command. Do not use @code{step} or you | |
4972 | will quickly get distracted; when the function you are stepping through | |
4973 | calls another function try only to get a big-picture understanding | |
4974 | (perhaps using the comment at the beginning of the function being | |
4975 | called) of what it does. This way you can identify which of the | |
4976 | functions being called by the function you are stepping through is the | |
4977 | one which you are interested in. You may need to examine the data | |
4978 | structures generated at each stage, with reference to the comments in | |
4979 | the header files explaining what the data structures are supposed to | |
4980 | look like. | |
4981 | ||
4982 | Of course, this same technique can be used if you are just reading the | |
4983 | code, rather than actually stepping through it. The same general | |
4984 | principle applies---when the code you are looking at calls something | |
4985 | else, just try to understand generally what the code being called does, | |
4986 | rather than worrying about all its details. | |
4987 | ||
56caf160 EZ |
4988 | @cindex command implementation |
4989 | A good place to start when tracking down some particular area is with | |
4990 | a command which invokes that feature. Suppose you want to know how | |
4991 | single-stepping works. As a @value{GDBN} user, you know that the | |
4992 | @code{step} command invokes single-stepping. The command is invoked | |
4993 | via command tables (see @file{command.h}); by convention the function | |
4994 | which actually performs the command is formed by taking the name of | |
4995 | the command and adding @samp{_command}, or in the case of an | |
4996 | @code{info} subcommand, @samp{_info}. For example, the @code{step} | |
4997 | command invokes the @code{step_command} function and the @code{info | |
4998 | display} command invokes @code{display_info}. When this convention is | |
4999 | not followed, you might have to use @code{grep} or @kbd{M-x | |
5000 | tags-search} in emacs, or run @value{GDBN} on itself and set a | |
5001 | breakpoint in @code{execute_command}. | |
5002 | ||
5003 | @cindex @code{bug-gdb} mailing list | |
c906108c SS |
5004 | If all of the above fail, it may be appropriate to ask for information |
5005 | on @code{bug-gdb}. But @emph{never} post a generic question like ``I was | |
5006 | wondering if anyone could give me some tips about understanding | |
25822942 | 5007 | @value{GDBN}''---if we had some magic secret we would put it in this manual. |
c906108c SS |
5008 | Suggestions for improving the manual are always welcome, of course. |
5009 | ||
33e16fad | 5010 | @node Debugging GDB,,,Hints |
c906108c | 5011 | |
25822942 | 5012 | @section Debugging @value{GDBN} with itself |
56caf160 | 5013 | @cindex debugging @value{GDBN} |
c906108c | 5014 | |
25822942 | 5015 | If @value{GDBN} is limping on your machine, this is the preferred way to get it |
c906108c SS |
5016 | fully functional. Be warned that in some ancient Unix systems, like |
5017 | Ultrix 4.2, a program can't be running in one process while it is being | |
56caf160 | 5018 | debugged in another. Rather than typing the command @kbd{@w{./gdb |
c906108c | 5019 | ./gdb}}, which works on Suns and such, you can copy @file{gdb} to |
56caf160 | 5020 | @file{gdb2} and then type @kbd{@w{./gdb ./gdb2}}. |
c906108c | 5021 | |
25822942 | 5022 | When you run @value{GDBN} in the @value{GDBN} source directory, it will read a |
c906108c SS |
5023 | @file{.gdbinit} file that sets up some simple things to make debugging |
5024 | gdb easier. The @code{info} command, when executed without a subcommand | |
25822942 | 5025 | in a @value{GDBN} being debugged by gdb, will pop you back up to the top level |
c906108c SS |
5026 | gdb. See @file{.gdbinit} for details. |
5027 | ||
5028 | If you use emacs, you will probably want to do a @code{make TAGS} after | |
5029 | you configure your distribution; this will put the machine dependent | |
5030 | routines for your local machine where they will be accessed first by | |
5031 | @kbd{M-.} | |
5032 | ||
25822942 | 5033 | Also, make sure that you've either compiled @value{GDBN} with your local cc, or |
c906108c SS |
5034 | have run @code{fixincludes} if you are compiling with gcc. |
5035 | ||
5036 | @section Submitting Patches | |
5037 | ||
56caf160 | 5038 | @cindex submitting patches |
c906108c | 5039 | Thanks for thinking of offering your changes back to the community of |
25822942 | 5040 | @value{GDBN} users. In general we like to get well designed enhancements. |
c906108c SS |
5041 | Thanks also for checking in advance about the best way to transfer the |
5042 | changes. | |
5043 | ||
25822942 DB |
5044 | The @value{GDBN} maintainers will only install ``cleanly designed'' patches. |
5045 | This manual summarizes what we believe to be clean design for @value{GDBN}. | |
c906108c SS |
5046 | |
5047 | If the maintainers don't have time to put the patch in when it arrives, | |
5048 | or if there is any question about a patch, it goes into a large queue | |
5049 | with everyone else's patches and bug reports. | |
5050 | ||
56caf160 | 5051 | @cindex legal papers for code contributions |
c906108c SS |
5052 | The legal issue is that to incorporate substantial changes requires a |
5053 | copyright assignment from you and/or your employer, granting ownership | |
5054 | of the changes to the Free Software Foundation. You can get the | |
9e0b60a8 JM |
5055 | standard documents for doing this by sending mail to @code{gnu@@gnu.org} |
5056 | and asking for it. We recommend that people write in "All programs | |
5057 | owned by the Free Software Foundation" as "NAME OF PROGRAM", so that | |
56caf160 EZ |
5058 | changes in many programs (not just @value{GDBN}, but GAS, Emacs, GCC, |
5059 | etc) can be | |
9e0b60a8 | 5060 | contributed with only one piece of legalese pushed through the |
be9c6c35 | 5061 | bureaucracy and filed with the FSF. We can't start merging changes until |
9e0b60a8 JM |
5062 | this paperwork is received by the FSF (their rules, which we follow |
5063 | since we maintain it for them). | |
c906108c SS |
5064 | |
5065 | Technically, the easiest way to receive changes is to receive each | |
56caf160 EZ |
5066 | feature as a small context diff or unidiff, suitable for @code{patch}. |
5067 | Each message sent to me should include the changes to C code and | |
5068 | header files for a single feature, plus @file{ChangeLog} entries for | |
5069 | each directory where files were modified, and diffs for any changes | |
5070 | needed to the manuals (@file{gdb/doc/gdb.texinfo} or | |
5071 | @file{gdb/doc/gdbint.texinfo}). If there are a lot of changes for a | |
5072 | single feature, they can be split down into multiple messages. | |
9e0b60a8 JM |
5073 | |
5074 | In this way, if we read and like the feature, we can add it to the | |
c906108c | 5075 | sources with a single patch command, do some testing, and check it in. |
56caf160 EZ |
5076 | If you leave out the @file{ChangeLog}, we have to write one. If you leave |
5077 | out the doc, we have to puzzle out what needs documenting. Etc., etc. | |
c906108c | 5078 | |
9e0b60a8 JM |
5079 | The reason to send each change in a separate message is that we will not |
5080 | install some of the changes. They'll be returned to you with questions | |
5081 | or comments. If we're doing our job correctly, the message back to you | |
c906108c | 5082 | will say what you have to fix in order to make the change acceptable. |
9e0b60a8 JM |
5083 | The reason to have separate messages for separate features is so that |
5084 | the acceptable changes can be installed while one or more changes are | |
5085 | being reworked. If multiple features are sent in a single message, we | |
5086 | tend to not put in the effort to sort out the acceptable changes from | |
5087 | the unacceptable, so none of the features get installed until all are | |
5088 | acceptable. | |
5089 | ||
5090 | If this sounds painful or authoritarian, well, it is. But we get a lot | |
5091 | of bug reports and a lot of patches, and many of them don't get | |
5092 | installed because we don't have the time to finish the job that the bug | |
c906108c SS |
5093 | reporter or the contributor could have done. Patches that arrive |
5094 | complete, working, and well designed, tend to get installed on the day | |
9e0b60a8 JM |
5095 | they arrive. The others go into a queue and get installed as time |
5096 | permits, which, since the maintainers have many demands to meet, may not | |
5097 | be for quite some time. | |
c906108c | 5098 | |
56caf160 EZ |
5099 | Please send patches directly to |
5100 | @email{gdb-patches@@sourceware.cygnus.com, the @value{GDBN} maintainers}. | |
c906108c SS |
5101 | |
5102 | @section Obsolete Conditionals | |
56caf160 | 5103 | @cindex obsolete code |
c906108c | 5104 | |
25822942 | 5105 | Fragments of old code in @value{GDBN} sometimes reference or set the following |
c906108c SS |
5106 | configuration macros. They should not be used by new code, and old uses |
5107 | should be removed as those parts of the debugger are otherwise touched. | |
5108 | ||
5109 | @table @code | |
c906108c SS |
5110 | @item STACK_END_ADDR |
5111 | This macro used to define where the end of the stack appeared, for use | |
5112 | in interpreting core file formats that don't record this address in the | |
25822942 DB |
5113 | core file itself. This information is now configured in BFD, and @value{GDBN} |
5114 | gets the info portably from there. The values in @value{GDBN}'s configuration | |
c906108c | 5115 | files should be moved into BFD configuration files (if needed there), |
25822942 | 5116 | and deleted from all of @value{GDBN}'s config files. |
c906108c SS |
5117 | |
5118 | Any @file{@var{foo}-xdep.c} file that references STACK_END_ADDR | |
5119 | is so old that it has never been converted to use BFD. Now that's old! | |
5120 | ||
5121 | @item PYRAMID_CONTROL_FRAME_DEBUGGING | |
5122 | pyr-xdep.c | |
5123 | @item PYRAMID_CORE | |
5124 | pyr-xdep.c | |
5125 | @item PYRAMID_PTRACE | |
5126 | pyr-xdep.c | |
5127 | ||
5128 | @item REG_STACK_SEGMENT | |
5129 | exec.c | |
5130 | ||
5131 | @end table | |
5132 | ||
56caf160 EZ |
5133 | @node Index |
5134 | @unnumbered Index | |
5135 | ||
5136 | @printindex cp | |
5137 | ||
449f3b6c AC |
5138 | @c TeX can handle the contents at the start but makeinfo 3.12 can not |
5139 | @ifinfo | |
c906108c | 5140 | @contents |
449f3b6c AC |
5141 | @end ifinfo |
5142 | @ifhtml | |
5143 | @contents | |
5144 | @end ifhtml | |
5145 | ||
c906108c | 5146 | @bye |