+ 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 pre-alpha version of GDB version 4, and has NOT been
+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. I have filed all the bug reports
-and fixes mailed to bug-gdb, and the fixes in particular will move
-into these sources as I find the time.
+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'.
+
-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.
+ Unpacking and Installation
-These generic files are packaged separately from GDB. You must obtain
-them separately from GDB, and unpack them into the same directory, so
-that the directories:
+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.
- bfd gdb include libiberty readline texinfo
+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, texinfo). Unpack that tar file in the same directory in
+which you unpacked the gdb-3.98.tar.Z file, so that for example the
+'bfd' directory sits next to the 'gdb' directory. The whole top-level
+directory will look like this with `ls -F':
-are all in the same directory. There should also be a "configure"
-script (and its parameters, in "configure.in" and "Makefile.in"),
-in the same place.
+ Makefile.in configure* include/ texinfo/
+ README.configure configure.in libiberty/
+ bfd/ gdb/ readline/
-Once you have this stuff unpacked, you can cd to the directory in which
-you unpacked them, and type:
+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.
-When building gdb's for multiple platforms, you must manually
-rebuild the libraries separately for each platform. FIXME FIXME no more!
-MENTION VPATH.
-
- cd ../readline
- [edit Makefile as appropriate]
- make
-
-A summary of features new since gdb-3.5 is in the file `WHATS.NEW'.
-
-The best way to build GDB (and the supporting libraries and include
-files), in my opinion, is in subdirectories. The configure script
-does this automatically if you specify more than one HOSTNAME; you can
-force it, even for one host only, by using configure's "+forcesubdirs"
-option (which you can abbreviate to +f). configure will create two
-directory levels, Host-machine and Target-machine. "machine"
-depends on your configuration options; the two directory levels
-reflect the fact that GDB can be configured for cross-debugging
-(described further below).
-
-For example, you can do
-
- cd .. (the directory *above* where this README is)
- configure +f mymachine
- cd Host-mymachine/Target-mymachine
- make
-
-Machine is like "vax" or "sun4". For more information type
-`./configure'. For a list of host machines, see the "xconfig"
-directory; for a list of targets, see the "tconfig" directory.
+ More Documentation
-Once you have done that, just `make' will do everything, producing an
-executable `gdb' in this directory. You can install it anywhere; it has
-no hardwired paths in it. However, you should make sure that the shell
-on your path (named by the SHELL environment variable) is publicly
-readable; various systems refuse to let GDB debug child programs which
-are not readable, and GDB uses the shell to start your program.
+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,
-You can also build gdb binaries in a completely different directory from its
-sources, by specifying "-destdir=YYY" to ./configure, giving it an absolute
-or relative path to the installation 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.
-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'
-where host is where GDB runs, and target is where your program runs.
-If you want a new (current to this release) version of the manual, you
-can run, from the GDB source directory,
- make gdb.dvi
-to make the TeX device-independent output file, or
- make gdb.info
-to make the "info" version for online browsing. The former assumes
-you have a running TeX on your system; the latter, a running makeinfo.
-The source for the GDB manual is in the doc/gdb.texinfo file (and a
-few other files it includes) provided with this distribution. The
-Makefile attempts to use a texinfo.tex from a "texinfo" directory
-parallel to the GDB directory (../texinfo/texinfo.tex, from the
-directory where this README is). For details see the texinfo manual
-(distributed with emacs and as a printed manual).
-
-About languages other than C...
+ 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). I am not aware of anyone who is working on getting gdb
-to use the syntax of any language other than C or C++. Pascal programs
-which use sets, subranges, file variables, or nested functions will not
-currently work.
+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.
-About kernel debugging...
-I have't done this myself so I can't really offer any advice.
-Remote debugging over serial lines is more like to be in a currently
-functioning state than the standalone gdb (kdb). FIXME.
+ Kernel debugging
-About remote 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.
-[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.
-This will get reworked before the initial release of 4.x. FIXME.
+ 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
RPC library. This would be a useful starting point for other remote-
via-ethernet back ends.
-About reporting bugs...
+[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.
-The correct address for reporting bugs found with gdb is
+
+ 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.
-About xgdb...
+"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.
+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...
+
+ 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 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 that express information
-about the target machine's registers, stack frame format and instructions.
+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,
Some machines use exec.c; some have the routines in <machine>-tdep.c
Since BFD, virtually all machines should use exec.c.
-About writing code for GDB...
+
+ 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
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. Thus in GDB 4.x these have all been consolidated
+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.
-About debugging gdb with itself...
-You 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 .
+ Debugging gdb with itself
-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.
+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.
\f
(this is for editing this file with GNU emacs)
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