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bd5635a1 RP |
1 | This is GDB, the GNU source-level debugger, presently running under |
2 | un*x. This is a pre-alpha version of GDB version 4, and has NOT been | |
3 | extensively tested. It surely has some bugs, both bugs that were | |
4 | present in version 3 and new bugs. I have filed all the bug reports | |
5 | and fixes mailed to bug-gdb, and the fixes in particular will move | |
6 | into these sources as I find the time. | |
7 | ||
8 | => THIS VERSION IS PARTICULARLY FRAGILE! <= | |
9 | ||
10 | It depends on a preliminary version of a new "binary file | |
11 | descriptor" library and a new global "include" directory, which | |
12 | are packaged separately from GDB. You must obtain, configure | |
13 | and build this library manually, then configure and build gdb. | |
14 | When building gdb's for multiple platforms, you must manually | |
15 | rebuild the bfd library separately for each platform. Yes, of | |
16 | course, we are working on this! FIXME! | |
17 | ||
18 | Configure bfd for your host system by: | |
19 | ||
20 | cd ../bfd | |
21 | edit Makefile | |
22 | make | |
23 | ||
24 | Then you can cd ../gdb-whatever, and config and build gdb. | |
25 | ||
26 | This release moves the generic GNU include files, the BFD library, | |
27 | and the getopt routines into the parent directory of gdb. The idea | |
28 | is that a variety of GNU tools can share a common copy of these things. | |
29 | ||
30 | A summary of features new since gdb-3.5 is in the file `WHATS.NEW'. | |
31 | ||
32 | The best way to build GDB, in my opinion, is in a subdirectory. I use | |
33 | a naming convention "=XXX" where XXX is the machine type I'm building | |
34 | for. Nothing depends on this, it's just how I remember which | |
35 | subdirectories are what. So, once you have the BFD library built for | |
36 | that machine, you can do: | |
37 | ||
38 | cd gdb-x.yy (the directory where this README is) | |
39 | mkdir =XXX (e.g. mkdir =vax) | |
40 | cd =XXX | |
41 | ../config.gdb machine | |
42 | make | |
43 | ||
44 | Machine is like "vax" or "sun4". For more information type `../config.gdb'. | |
45 | ||
46 | Once you have done that, just `make' will do everything, producing an | |
47 | executable `gdb' in this directory. | |
48 | ||
49 | You can also build gdb binaries in a completely different directory from its | |
50 | sources, by specifying "srcdir=YYY" to config.gdb, giving it an absolute | |
51 | or relative path to the source directory. | |
52 | ||
53 | GDB can be used as a cross-debugger, running on a machine of one type | |
54 | while debugging a program running on a machine of another type. You | |
55 | configure it this way by specifying `config.gdb host target' where host | |
56 | is where GDB runs, and target is where your program runs. | |
57 | ||
58 | If you want a new (current to this release) version of the manual, you | |
59 | will have to use the gdb.texinfo file provided with this distribution. | |
60 | For details see the texinfo manual (distributed with emacs and as a | |
61 | printed manual). | |
62 | ||
63 | About languages other than C... | |
64 | ||
65 | C++ support has been integrated into gdb. GDB should work with FORTRAN | |
66 | programs (if you have problem, please send a bug report; note that you | |
67 | may have to refer to some FORTRAN variables with a trailing | |
68 | underscore), but I am not aware of anyone who is working on getting it | |
69 | to use the syntax of any language other than C or C++. Pascal programs | |
70 | which use sets, subranges, file variables, or nested functions will not | |
71 | currently work. | |
72 | ||
73 | About kernel debugging... | |
74 | ||
75 | I have't done this myself so I can't really offer any advice. | |
76 | Remote debugging over serial lines is more like to be in a currently | |
77 | functioning state than the standalone gdb (kdb). FIXME. | |
78 | ||
79 | About remote debugging... | |
80 | ||
81 | [This section seems to be out of date, I have never seen the "rapp" | |
82 | program, though I would like to. FIXME.] | |
83 | `rapp' runs under unix and acts as a remote stub (like remote-multi.shar | |
84 | distributed with GDB version 3). Currently it just works over UDP | |
85 | (network), not over a serial line. To get it running | |
86 | * Compile GDB on the host machine as usual | |
87 | * Compile rapp on the target machine, giving for both host and target | |
88 | the type of the target machine | |
89 | * Install "gdb" in /etc/services on both machines. | |
90 | ||
91 | This will get reworked before the initial release of 4.x. FIXME. | |
92 | ||
93 | The two files remote-multi.shar and remote-sa.m68k.shar contain two | |
94 | examples of a remote stub to be used with remote.c. The the -multi | |
95 | file is a general stub that can probably be running on various | |
96 | different flavors of unix to allow debugging over a serial line from | |
97 | one machine to another. The remote-sa.m68k.shar is designed to run | |
98 | standalone on a 68k type cpu and communicate properley with the | |
99 | remote.c stub over a serial line. | |
100 | ||
101 | The files remote-eb.c and remote-nindy.c are two examples of remote | |
102 | interfaces for talking to existing ROM monitors (for the AMD 29000 and the | |
103 | Intel 960 repsectively). There is also a remote interface for the | |
104 | VxWorks realtime kernel, which communicates over TCP/IP, in remote-vx.c | |
105 | and the vx-share subdirectory. | |
106 | ||
107 | About reporting bugs... | |
108 | ||
109 | The correct address for reporting bugs found with gdb is | |
110 | "bug-gdb@prep.ai.mit.edu". Please email all bugs to that address. | |
111 | ||
112 | About xgdb... | |
113 | ||
114 | Hopefully a new xgdb will be in 4.x. | |
115 | ||
116 | xgdb.c was provided to us by the user community; it is not an integral | |
117 | part of the gdb distribution. The problem of providing visual | |
118 | debugging support on top of gdb is peripheral to the GNU project and | |
119 | (at least right now) we can't afford to put time into it. So while we | |
120 | will be happy to incorporate user fixes to xgdb.c, we do not guarantee | |
121 | that it will work and we will not fix bugs reported in it. See | |
122 | XGDB-README for one person's opinion about what is wrong with the | |
123 | current xgdb. Someone is working on writing a new XGDB, so improving | |
124 | (e.g. by fixing it so that it will work, if it doesn't currently) the | |
125 | current one is not worth it. | |
126 | ||
127 | For those intersted in auto display of source and the availability of | |
128 | an editor while debugging I suggest trying gdb-mode in gnu-emacs | |
129 | (Try typing M-x gdb RETURN). Comments on this mode are welcome. | |
130 | ||
131 | About the machine-dependent files... | |
132 | ||
133 | tconfig/<machine> | |
134 | This contains Makefile stuff for when the target system is <machine>. | |
135 | It also specifies the name of the tm-XXX.h file for this machine. | |
136 | ||
137 | xconfig/<machine> | |
138 | This contains Makefile stuff for when the host system is <machine>. | |
139 | It also specifies the name of the xm-XXX.h file for this machine. | |
140 | ||
141 | tm-XXX.h (tm.h is a link to this file, created by config.gdb). | |
142 | This file contains macro definitions that express information | |
143 | about the target machine's registers, stack frame format and instructions. | |
144 | ||
145 | xm-XXX.h (xm.h is a link to this file, created by config.gdb). | |
146 | This contains macro definitions describing the host system environment, | |
147 | such as byte order, host C compiler and library, ptrace support, | |
148 | and core file structure. | |
149 | ||
150 | <machine>-opcode.h | |
151 | <machine>-pinsn.c | |
152 | These files contain the information necessary to print instructions | |
153 | for your cpu type. <machine>-opcode.h includes some large initialized | |
154 | data structures, which is strange for a ".h" file, but it's OK since | |
155 | it is only included in one place. <machine>-opcode.h is shared | |
156 | between the debugger and the assembler (if the GNU assembler has been | |
157 | ported to that machine), whereas <machine>-pinsn.c is specific to GDB. | |
158 | ||
159 | <machine>-tdep.c | |
160 | This file contains any miscellaneous code required for this machine | |
161 | as a target. On some machines it doesn't exist at all. Its existence | |
162 | is specified in the tconfig/XXX file. | |
163 | ||
164 | <machine>-xdep.c | |
165 | This file contains any miscellaneous code required for this machine | |
166 | as a host. On some machines it doesn't exist at all. Its existence | |
167 | is specified in the xconfig/XXX file. | |
168 | ||
169 | infptrace.c | |
170 | This is the low level interface to inferior processes for systems | |
171 | using the Unix ptrace call in a vanilla way. Some systems have their | |
172 | own routines in <machine>-xdep.c. Whether or not it is used | |
173 | is specified in the xconfig/XXX file. | |
174 | ||
175 | coredep.c | |
176 | Machine and system-dependent aspects of reading core files. Some | |
177 | machines use coredep.c; some have the routines in <machine>-xdep.c. | |
178 | Whether or not it is used is specified in the xconfig/XXX file. | |
179 | Now that BFD is used to read core files, virtually all machines should | |
180 | use coredep.c and should just provide fetch_core_registers in | |
181 | <machine>-xdep.c. | |
182 | ||
183 | exec.c | |
184 | Machine and system-dependent aspects of reading executable files. | |
185 | Some machines use exec.c; some have the routines in <machine>-tdep.c | |
186 | Since BFD, virtually all machines should use exec.c. | |
187 | ||
188 | About writing code for GDB... | |
189 | ||
190 | We appreciate having users contribute code that is of general use, but | |
191 | for it to be included in future GDB releases it must be cleanly | |
192 | written. We do not want to include changes that will needlessly make | |
193 | future maintainance difficult. It is not much harder to do things | |
194 | right, and in the long term it is worth it to the GNU project, and | |
195 | probably to you individually as well. | |
196 | ||
197 | Please code according to the GNU coding standards. If you do not have | |
198 | a copy, you can request one by sending mail to gnu@prep.ai.mit.edu. | |
199 | ||
200 | If you make substantial changes, you'll have to file a copyright | |
201 | assignment with the Free Software Foundation before we can produce a | |
202 | release that includes your changes. Send mail requesting the copyright | |
203 | assignment to gnu@prep.ai.mit.edu. Do this early, like before the | |
204 | changes actually work, or even before you start them, because a manager | |
205 | or lawyer on your end will probably make this a slow process. | |
206 | ||
207 | Please try to avoid making machine-specific changes to | |
208 | machine-independent files. If this is unavoidable, put a hook in the | |
209 | machine-independent file which calls a (possibly) machine-dependent | |
210 | macro (for example, the IGNORE_SYMBOL macro can be used for any | |
211 | symbols which need to be ignored on a specific machine. Calling | |
212 | IGNORE_SYMBOL in dbxread.c is a lot cleaner than a maze of #if | |
213 | defined's). The machine-independent code should do whatever "most" | |
214 | machines want if the macro is not defined in param.h. Using #if | |
215 | defined can sometimes be OK (e.g. SET_STACK_LIMIT_HUGE) but should be | |
216 | conditionalized on a specific feature of an operating system (set in | |
217 | tm.h or xm.h) rather than something like #if defined(vax) or #if | |
218 | defined(SYSV). If you use an #ifdef on some symbol that is defined | |
219 | in a header file (e.g. #ifdef TIOCSETP), *please* make sure that you | |
220 | have #include'd the relevant header file in that module! | |
221 | ||
222 | It is better to replace entire routines which may be system-specific, | |
223 | rather than put in a whole bunch of hooks which are probably not going | |
224 | to be helpful for any purpose other than your changes. For example, | |
225 | if you want to modify dbxread.c to deal with DBX debugging symbols | |
226 | which are in COFF files rather than BSD a.out files, do something | |
227 | along the lines of a macro GET_NEXT_SYMBOL, which could have | |
228 | different definitions for COFF and a.out, rather than trying to put | |
229 | the necessary changes throughout all the code in dbxread.c that | |
230 | currently assumes BSD format. | |
231 | ||
232 | Please avoid duplicating code. For example, in GDB 3.x all the stuff | |
233 | in infptrace.c was duplicated in *-dep.c, and so changing something | |
234 | was very painful. Thus in GDB 4.x these have all been consolidated | |
235 | into infptrace.c. infptrace.c can deal with variations between | |
236 | systems the same way any system-independent file would (hooks, #if | |
237 | defined, etc.), and machines which are radically different don't need | |
238 | to use infptrace.c at all. The same was true of core_file_command | |
239 | and exec_file_command. | |
240 | ||
241 | About debugging gdb with itself... | |
242 | ||
243 | You probably want to do a "make TAGS" after you configure your | |
244 | distribution; this will put the machine dependent routines for your | |
245 | local machine where they will be accessed first by a M-period . | |
246 | ||
247 | Also, make sure that you've compiled gdb with your local cc or taken | |
248 | appropriate precautions regarding ansification of include files. See | |
249 | the Makefile for more information. | |
250 | ||
251 | When you run gdb in this directory, it will read a ".gdbinit" file that | |
252 | sets up some simple things to make debugging gdb easier. The "info" | |
253 | command, when executed without a subcommand in a gdb being debugged by | |
254 | gdb, will pop you back up to the top level gdb. See .gdbinit for details. | |
255 | \f | |
256 | (this is for editing this file with GNU emacs) | |
257 | Local Variables: | |
258 | mode: text | |
259 | End: |