Sprite 1984

home *** CD-ROM | disk | FTP | other *** search

/ Sprite 1984 - 1993 / Sprite 1984 - 1993.iso / src / cmds / gdb.new / gdb-3.98 / gdb / README < prev next >

Wrap

Text File | 1991-08-01 | 19.2 KB | 469 lines

README for gdb-3.98 beta release John Gilmore 31 July 91 This is GDB, the GNU source-level debugger, presently running under un*x. This is a beta test version of GDB version 4, and has not been extensively tested. It surely has some bugs, both bugs that were present in version 3, and new bugs. If your favorite bugfix is not yet present here, I encourage you to port it into this version and then send the diffs to bug-gdb@prep.ai.mit.edu. A summary of features new since gdb-3.5 is in the file `WHATS.NEW'. Unpacking and Installation This release moves the generic GNU include files, the BFD ("binary file description") library, the getopt routines, obstacks, and the readline library into the parent directory of gdb. The idea is that a variety of GNU tools can share a common copy of these things. These generic files are packaged separately from GDB, in a tar file called "bfd.ilrt-3.98.tar.Z". ("ilrt" stands for include, libiberty, readline, and texinfo). Unpack that tar file in the same directory in which you unpacked the gdb-3.98.tar.Z file, so that all the files in it will sit next to the 'gdb' directory. The whole top-level directory will look like this with `ls -F': Makefile.in configure* include/ texinfo/ README.configure configure.in libiberty/ bfd/ gdb/ readline/ Once you have this stuff unpacked, and your current directory is here, you can type: ./configure HOSTNAME make and all the libraries, as well as GDB will be configured and built. If you get compiler warnings during this stage, see the `Reporting Bugs' section below; there are a few known problems. GDB can be used as a cross-debugger, running on a machine of one type while debugging a program running on a machine of another type. You configure it this way by specifying `./configure host -target=target'; see below. More Documentation The GDB manual is much expanded and improved. For online browsing, gdb/gdb.info is the main file, and there are gdb/gdb.info-1 through -6 files that can be installed into your main `info' tree. If you want a printed version of the manual, you can run, from the GDB source directory, make gdb.dvi to make the TeX device-independent output file. This assumes you have a running TeX on your system. The source for the GDB manual is in doc/gdb.texinfo (and a few other files it includes), provided with this distribution. The Makefile attempts to use the texinfo.tex supplied as part of the BFD-and-libraries tar file, since the manual uses Texinfo-2 which is not in common use yet. Configuration Details (extracted from gdb.texinfo) GDB is distributed with a `configure' script that automates the process of preparing GDB for installation; you can then use `make' to build the `gdb' program. The `configure' script that's specific to GDB is distributed in the main GDB source directory. However, building GDB also requires several other directories of source common to multiple GNU programs. These directories (GNU libraries and includes) are distributed separately, but their `configure' scripts and `Makefile's are designed to work together. To ensure that GDB's `Makefile' can find all the pieces, you should make a single overall directory to hold the directories of source for GNU libraries and includes, and you should install the GDB source directory there too. In this Appendix, we refer to the directory of GNU source directories as GNUSRC. At a minimum, to build GDB you need the directories `GNUSRC/gdb' the source specific to GDB itself `GNUSRC/bfd' source for the Binary File Descriptor Library `GNUSRC/include' GNU include files `GNUSRC/libiberty' source for the `-liberty' free software library `GNUSRC/readline' source for the GNU command-line interface Each of these directories has its own `configure' script. GNUSRC has an overall `configure' script, which is distributed with the GNU libraries and includes. `configure' is designed to be called recursively, so it is most convenient to run `configure' from the GNUSRC directory. The simplest way to configure and build GDB is the following: cd GNUSRC ./configure HOST make where HOST is something like `sun4' or `vax', that identifies the platform where GDB will run. This builds the three libraries `bfd', `readline', and `libiberty', then `gdb' itself. The configured source files, and the binaries, are left in the corresponding source directories. You can install `gdb' anywhere; it has no hardwired paths. However, you should make sure that the shell on your path (named by the `SHELL' environment variable) is publicly readable; some systems refuse to let GDB debug child processes whose programs are not readable, and GDB uses the shell to start your program. Configuration Subdirectories If you build GDB for several host or target machines, and if your `make' program handles the `VPATH' feature (GNU `make' does), it is most convenient instead to build the different GDB configurations in subdirectories (separate from the source). `configure' does this for you when you simultaneously specify several configurations; but it's a good habit even for a single configuration. You can specify the use of subdirectories using the `+forcesubdirs' option (abbreviated `+f'). For example, you can build GDB on a Sun 4 as follows: cd GNUSRC ./configure +f sun4 cd Host-sun4/Target-sun4 make When `configure' uses subdirectories to build programs or libraries, it creates nested directories `Host-HOST/Target-MACHINE'. This is because GDB can be configured for cross-compiling: GDB can run on one machine (the host) while debugging programs that run on another machine (the target). You specify cross-debugging targets by giving the `+target=MACHINE' option to `configure'. Specifying only hosts still gives you two levels of subdirectory for each host, with the same machine-name suffix on both. On the other hand, whenever you specify both hosts and targets on the same command line, `configure' creates all combinations of the hosts and targets you list. When you run `make' to build a program or library, you must run it in a configured directory. If you made a single configuration, without subdirectories, run `make' in the source directory. If you have `Host-HOST/Target-MACHINE' subdirectories, run `make' in those subdirectories. Each `configure' and `Makefile' under each source directory runs recursively, so that typing `make' in GNUSRC (or in a `GNUSRC/Host-HOST/Target-MACHINE' subdirectory) builds all the required libraries, then GDB. If you run `configure' from a directory (such as GNUSRC) that contains source directories for multiple libraries or programs, `configure' creates the `Host-HOST/Target-MACHINE' subdirectories in each library or program's source directory. For example, typing: cd GNUSRC configure sun4 +target=vx960 creates the following directories: GNUSRC/Host-sun4/Target-vx960 GNUSRC/bfd/Host-sun4/Target-vx960 GNUSRC/gdb/Host-sun4/Target-vx960 GNUSRC/libiberty/Host-sun4/Target-vx960 GNUSRC/readline/Host-sun4/Target-vx960 The `Makefile' in `GNUSRC/Host-sun4/Target-vx960' will `cd' to the appropriate lower-level directories (such as `GNUSRC/bfd/Host-sun4/Target-vx960'), building each in turn. When you have multiple hosts or targets configured, you can run `make' on them in parallel (for example, if they are NFS-mounted on each of the hosts); they will not interfere with each other. `configure' Options Here is a summary of all the `configure' options and arguments that you might use for building GDB: configure [+destdir=DIR] [+forcesubdirs] [+norecur] [+rm] [+target=MACHINE...] HOST... You may introduce options with the character `-' rather than `+' if you prefer; but options introduced with `+' may be truncated. `+destdir=DIR' DIR is an installation directory *path prefix*. After you configure with this option, `make install' will install GDB as `DIR/bin/gdb', and the libraries in `DIR/lib'. If you specify `+destdir=/usr/local', for example, `make install' creates `/usr/local/bin/gdb'. `+forcesubdirs' Write configuration specific files in subdirectories of the form Host-MACHINE/Target-MACHINE (and configure the `Makefile' to write binaries there too). Without this option, if you specify only one configuration for GDB, `configure' will use the same directory for source, configured files, and binaries. This option is used automatically if you specify more than one HOST or more than one `+target=MACHINE' option on the `configure' command line. `+norecur' Configure only the directory where `configure' is executed; do not propagate configuration to subdirectories. `+rm' Remove the configuration specified by other arguments. `+target=MACHINE ...' Configure GDB for cross-debugging programs running on each specified MACHINE. You may specify as many `+target' options as you wish. To see a list of available targets, execute `ls tconfig' in the GDB source directory. Without this option, GDB is configured to debug programs that run on the same machine (HOST) as GDB itself. `HOST ...' Configure GDB to run on each specified HOST. You may specify as many host names as you wish. To see a list of available hosts, execute `ls xconfig' in the GDB source directory. `configure' accepts other options, for compatibility with configuring other GNU tools recursively; but these are the only options that affect GDB or its supporting libraries. Languages other than C C++ support has been integrated into gdb. GDB should work with FORTRAN programs. (If you have problems, please send a bug report; you may have to refer to some FORTRAN variables with a trailing underscore). There is an effort to produce a GDB that works with Modula-2. I am not aware of anyone who is working on getting gdb to use the syntax of any other language. Pascal programs which use sets, subranges, file variables, or nested functions will not currently work. Kernel debugging I have't done this myself so I can't really offer any advice. Remote debugging over serial lines works fine, but the kernel debugging code in here has not been tested in years. Van Jacobson claims to have better kernel debugging, but won't release it for ordinary mortals. Remote debugging The files m68k-stub.c and i386-stub.c contain two examples of remote stubs to be used with remote.c. They are designeded to run standalone on a 68k or 386 cpu and communicate properly with the remote.c stub over a serial line. The file rem-multi.shar contains a general stub that can probably run on various different flavors of unix to allow debugging over a serial line from one machine to another. The files remote-eb.c and remote-nindy.c are two examples of remote interfaces for talking to existing ROM monitors (for the AMD 29000 and the Intel 960 repsectively). Remote-vx.c and the vx-share subdirectory contain a remote interface for the VxWorks realtime kernel, which communicates over TCP using the Sun RPC library. This would be a useful starting point for other remote- via-ethernet back ends. [This section seems to be out of date, I have never seen the "rapp" program, though I would like to. FIXME.] `rapp' runs under unix and acts as a remote stub (like rem-multi.shar distributed with GDB version 3). Currently it just works over UDP (network), not over a serial line. To get it running * Compile GDB on the host machine as usual * Compile rapp on the target machine, giving for both host and target the type of the target machine * Install "gdb" in /etc/services on both machines. Reporting Bugs The correct address for reporting bugs found in gdb is "bug-gdb@prep.ai.mit.edu". Please email all bugs to that address. "mcheck.c", line 32, will produce a pointer conversion warning, which can be ignored. When gdb reads object files produced by the Sun bundled C compiler, you will often get a "bad block start address patched" message. You can shut off such messages with the command `set complaint 0' (which you can put in your ~/.gdbinit if you like). Messages like this during symbol reading indicate some mismatch between the object file and GDB's symbol reading code (in this case, it's a mismatch between the specs for the object file format, and what Sun's compiler actually outputs). If you port gdb to a new machine, please send the required changes to bug-gdb@prep.ai.mit.edu. If your changes are more than a few lines, obtain and send in a copyright assignment from gnu@prep.ai.mit.edu, as described in the section `Writing Code for GDB'. X Windows versus GDB xgdb is obsolete. We are not doing any development or support of it. There is an "xxgdb", which shows more promise, which was posted to comp.sources.x. For those intersted in auto display of source and the availability of an editor while debugging I suggest trying gdb-mode in gnu-emacs (Try typing M-x gdb RETURN). Comments on this mode are welcome. About the machine-dependent files tconfig/<machine> This contains Makefile stuff for when the target system is <machine>. It also specifies the name of the tm-XXX.h file for this machine. xconfig/<machine> This contains Makefile stuff for when the host system is <machine>. It also specifies the name of the xm-XXX.h file for this machine. tm-XXX.h (tm.h is a link to this file, created by configure). This file contains macro definitions about the target machine's registers, stack frame format and instructions. xm-XXX.h (xm.h is a link to this file, created by configure). This contains macro definitions describing the host system environment, such as byte order, host C compiler and library, ptrace support, and core file structure. <machine>-opcode.h <machine>-pinsn.c These files contain the information necessary to print instructions for your cpu type. <machine>-opcode.h includes some large initialized data structures, which is strange for a ".h" file, but it's OK since it is only included in one place. <machine>-opcode.h is shared between the debugger and the assembler (if the GNU assembler has been ported to that machine), whereas <machine>-pinsn.c is specific to GDB. <machine>-tdep.c This file contains any miscellaneous code required for this machine as a target. On some machines it doesn't exist at all. Its existence is specified in the tconfig/XXX file. <machine>-xdep.c This file contains any miscellaneous code required for this machine as a host. On some machines it doesn't exist at all. Its existence is specified in the xconfig/XXX file. infptrace.c This is the low level interface to inferior processes for systems using the Unix ptrace call in a vanilla way. Some systems have their own routines in <machine>-xdep.c. Whether or not it is used is specified in the xconfig/XXX file. coredep.c Machine and system-dependent aspects of reading core files. Some machines use coredep.c; some have the routines in <machine>-xdep.c. Whether or not it is used is specified in the xconfig/XXX file. Now that BFD is used to read core files, virtually all machines should use coredep.c and should just provide fetch_core_registers in <machine>-xdep.c. exec.c Machine and system-dependent aspects of reading executable files. Some machines use exec.c; some have the routines in <machine>-tdep.c Since BFD, virtually all machines should use exec.c. Writing Code for GDB We appreciate having users contribute code that is of general use, but for it to be included in future GDB releases it must be cleanly written. We do not want to include changes that will needlessly make future maintainance difficult. It is not much harder to do things right, and in the long term it is worth it to the GNU project, and probably to you individually as well. Please code according to the GNU coding standards. If you do not have a copy, you can request one by sending mail to gnu@prep.ai.mit.edu. If you make substantial changes, you'll have to file a copyright assignment with the Free Software Foundation before we can produce a release that includes your changes. Send mail requesting the copyright assignment to gnu@prep.ai.mit.edu. Do this early, like before the changes actually work, or even before you start them, because a manager or lawyer on your end will probably make this a slow process. Please try to avoid making machine-specific changes to machine-independent files. If this is unavoidable, put a hook in the machine-independent file which calls a (possibly) machine-dependent macro (for example, the IGNORE_SYMBOL macro can be used for any symbols which need to be ignored on a specific machine. Calling IGNORE_SYMBOL in dbxread.c is a lot cleaner than a maze of #if defined's). The machine-independent code should do whatever "most" machines want if the macro is not defined in param.h. Using #if defined can sometimes be OK (e.g. SET_STACK_LIMIT_HUGE) but should be conditionalized on a specific feature of an operating system (set in tm.h or xm.h) rather than something like #if defined(vax) or #if defined(SYSV). If you use an #ifdef on some symbol that is defined in a header file (e.g. #ifdef TIOCSETP), *please* make sure that you have #include'd the relevant header file in that module! It is better to replace entire routines which may be system-specific, rather than put in a whole bunch of hooks which are probably not going to be helpful for any purpose other than your changes. For example, if you want to modify dbxread.c to deal with DBX debugging symbols which are in COFF files rather than BSD a.out files, do something along the lines of a macro GET_NEXT_SYMBOL, which could have different definitions for COFF and a.out, rather than trying to put the necessary changes throughout all the code in dbxread.c that currently assumes BSD format. Please avoid duplicating code. For example, in GDB 3.x all the stuff in infptrace.c was duplicated in *-dep.c, and so changing something was very painful. In GDB 4.x, these have all been consolidated into infptrace.c. infptrace.c can deal with variations between systems the same way any system-independent file would (hooks, #if defined, etc.), and machines which are radically different don't need to use infptrace.c at all. The same was true of core_file_command and exec_file_command. Debugging gdb with itself If gdb is limping on your machine, this is the preferred way to get it fully functional. Be warned that in some ancient Unix systems, like Ultrix 4.0, a program can't be running in one process while it is being debugged in another. Rather than doing "./gdb ./gdb", which works on Suns and such, you can copy gdb to gdb2 and then do "./gdb ./gdb2". When you run gdb in this directory, it will read a ".gdbinit" file that sets up some simple things to make debugging gdb easier. The "info" command, when executed without a subcommand in a gdb being debugged by gdb, will pop you back up to the top level gdb. See .gdbinit for details. If you use emacs, you will probably want to do a "make TAGS" after you configure your distribution; this will put the machine dependent routines for your local machine where they will be accessed first by a M-period. Also, make sure that you've compiled gdb with your local cc or taken appropriate precautions regarding ansification of include files. See the Makefile for more information. (this is for editing this file with GNU emacs) Local Variables: mode: text End: