-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
-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.
+ README for gdb-4.7 release
+ Stu Grossman & John Gilmore 23 October 1992
-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.
+This is GDB, the GNU source-level debugger, presently running under un*x.
+A summary of new features is in the file `NEWS'.
-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:
- bfd gdb include libiberty readline texinfo
+Unpacking and Installation -- quick overview
+==========================
-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.
+In this release, the GDB debugger sources, the generic GNU include
+files, the BFD ("binary file description") library, the readline library,
+and other libraries all have directories of their own underneath
+the gdb-4.7 directory. The idea is that a variety of GNU tools can
+share a common copy of these things. Configuration scripts and
+makefiles exist to cruise up and down this directory tree and
+automatically build all the pieces in the right order.
-Once you have this stuff unpacked, you can cd to the directory in which
-you unpacked them, and type:
+When you unpack the gdb-4.7.tar.Z file, you'll get a directory called
+`gdb-4.7', which contains:
- ./configure HOSTNAME
+ COPYING.LIB config/ configure.texi mmalloc/
+ Makefile.in config.sub* gdb/ move-if-change*
+ README configure* glob/ opcodes/
+ bfd/ configure.in include/ readline/
+ cfg-paper.texi configure.man libiberty/ texinfo/
+
+To build GDB, you can just do:
+
+ cd gdb-4.7
+ ./configure HOSTTYPE (e.g. sun4, decstation)
make
+ cp gdb/gdb /usr/local/bin/gdb (or wherever you want)
-and all the libraries, as well as GDB will be configured and built.
+This will configure and build all the libraries as well as GDB.
+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. 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
+More Documentation
+******************
-A summary of features new since gdb-3.5 is in the file `WHATS.NEW'.
+ The GDB 4 release includes an already-formatted reference card, ready
+for printing with PostScript or GhostScript, in the `gdb' subdirectory
+of the main source directory--in `gdb-4.7/gdb/refcard.ps' of the
+version 4.7 release. If you can use PostScript or GhostScript with your
+printer, you can print the reference card immediately with `refcard.ps'.
-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).
+ The release also includes the source for the reference card. You
+can format it, using TeX, by typing:
-For example, you can do
+ make refcard.dvi
- cd .. (the directory *above* where this README is)
- configure +f mymachine
- cd Host-mymachine/Target-mymachine
- make
+ The GDB reference card is designed to print in landscape mode on US
+"letter" size paper; that is, on a sheet 11 inches wide by 8.5 inches
+high. You will need to specify this form of printing as an option to
+your DVI output program.
-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.
+ All the documentation for GDB comes as part of the machine-readable
+distribution. The documentation is written in Texinfo format, which is
+a documentation system that uses a single source file to produce both
+on-line information and a printed manual. You can use one of the Info
+formatting commands to create the on-line version of the documentation
+and TeX (or `texi2roff') to typeset the printed version.
+ GDB includes an already formatted copy of the on-line Info version of
+this manual in the `gdb' subdirectory. The main Info file is
+`gdb-VERSION-NUMBER/gdb/gdb.info', and it refers to subordinate files
+matching `gdb.info*' in the same directory. If necessary, you can
+print out these files, or read them with any editor; but they are
+easier to read using the `info' subsystem in GNU Emacs or the
+standalone `info' program, available as part of the GNU Texinfo
+distribution.
-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.
+ If you want to format these Info files yourself, you need one of the
+Info formatting programs, such as `texinfo-format-buffer' or `makeinfo'.
-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.
+ If you have `makeinfo' installed, and are in the top level GDB
+source directory (`gdb-4.7', in the case of version 4.7), you can make
+the Info file by typing:
-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...
-
-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.
-
-About kernel debugging...
+ cd gdb
+ make gdb.info
-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.
+ If you want to typeset and print copies of this manual, you need
+TeX, a printing program such as `lpr', and `texinfo.tex', the Texinfo
+definitions file.
+
+ TeX is typesetting program; it does not print files directly, but
+produces output files called DVI files. To print a typeset document,
+you need a program to print DVI files. If your system has TeX
+installed, chances are it has such a program. The precise command to
+use depends on your system; `lpr -d' is common; another is `dvips'.
+The DVI print command may require a file name without any extension or
+a `.dvi' extension.
+
+ TeX also requires a macro definitions file called `texinfo.tex'.
+This file tells TeX how to typeset a document written in Texinfo
+format. On its own, TeX cannot read, much less typeset a Texinfo file.
+ `texinfo.tex' is distributed with GDB and is located in the
+`gdb-VERSION-NUMBER/texinfo' directory.
+
+ If you have TeX and a DVI printer program installed, you can typeset
+and print this manual. First switch to the the `gdb' subdirectory of
+the main source directory (for example, to `gdb-4.7/gdb') and then type:
+
+ make gdb.dvi
+
+
+Installing GDB
+***************
+
+ GDB comes with a `configure' script that automates the process of
+preparing GDB for installation; you can then use `make' to build the
+program.
+
+ The GDB distribution includes all the source code you need for GDB in
+a single directory, whose name is usually composed by appending the
+version number to `gdb'.
+
+ For example, the GDB version 4.7 distribution is in the `gdb-4.7'
+directory. That directory contains:
+
+`gdb-4.7/configure (and supporting files)'
+ script for configuring GDB and all its supporting libraries.
+
+`gdb-4.7/gdb'
+ the source specific to GDB itself
+
+`gdb-4.7/bfd'
+ source for the Binary File Descriptor library
+
+`gdb-4.7/include'
+ GNU include files
+
+`gdb-4.7/libiberty'
+ source for the `-liberty' free software library
+
+`gdb-4.7/opcodes'
+ source for the library of opcode tables and disassemblers
+
+`gdb-4.7/readline'
+ source for the GNU command-line interface
+
+`gdb-4.7/glob'
+ source for the GNU filename pattern-matching subroutine
+
+`gdb-4.7/mmalloc'
+ source for the GNU memory-mapped malloc package
+
+ The simplest way to configure and build GDB is to run `configure'
+from the `gdb-VERSION-NUMBER' source directory, which in this example
+is the `gdb-4.7' directory.
+
+ First switch to the `gdb-VERSION-NUMBER' source directory if you are
+not already in it; then run `configure'. Pass the identifier for the
+platform on which GDB will run as an argument.
+
+ For example:
+
+ cd gdb-4.7
+ ./configure HOST
+ make
+
+where HOST is an identifier such as `sun4' or `decstation', that
+identifies the platform where GDB will run.
+
+ Running `configure HOST' followed by `make' builds the `bfd',
+`readline', `mmalloc', and `libiberty' libraries, then `gdb' itself.
+The configured source files, and the binaries, are left in the
+corresponding source directories.
+
+ `configure' is a Bourne-shell (`/bin/sh') script; if your system
+does not recognize this automatically when you run a different shell,
+you may need to run `sh' on it explicitly:
+
+ sh configure HOST
+
+ If you run `configure' from a directory that contains source
+directories for multiple libraries or programs, such as the `gdb-4.7'
+source directory for version 4.7, `configure' creates configuration
+files for every directory level underneath (unless you tell it not to,
+with the `--norecursion' option).
-About remote debugging...
+ You can run the `configure' script from any of the subordinate
+directories in the GDB distribution, if you only want to configure that
+subdirectory; but be sure to specify a path to it.
+
+ For example, with version 4.7, type the following to configure only
+the `bfd' subdirectory:
+
+ cd gdb-4.7/bfd
+ ../configure HOST
-[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.
+ 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. Remember that GDB uses the
+shell to start your program--some systems refuse to let GDB debug child
+processes whose programs are not readable.
-This will get reworked before the initial release of 4.x. FIXME.
-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.
+Compiling GDB in Another Directory
+===================================
+
+ If you want to run GDB versions for several host or target machines,
+you'll need a different `gdb' compiled for each combination of host and
+target. `configure' is designed to make this easy by allowing you to
+generate each configuration in a separate subdirectory, rather than in
+the source directory. If your `make' program handles the `VPATH'
+feature (GNU `make' does), running `make' in each of these directories
+then builds the `gdb' program specified there.
+
+ To build `gdb' in a separate directory, run `configure' with the
+`--srcdir' option to specify where to find the source. (You'll also
+need to specify a path to find `configure' itself from your working
+directory. If the path to `configure' would be the same as the
+argument to `--srcdir', you can leave out the `--srcdir' option; it
+will be assumed.)
+
+ For example, with version 4.7, you can build GDB in a separate
+directory for a Sun 4 like this:
+
+ cd gdb-4.7
+ mkdir ../gdb-sun4
+ cd ../gdb-sun4
+ ../gdb-4.7/configure sun4
+ make
+
+ When `configure' builds a configuration using a remote source
+directory, it creates a tree for the binaries with the same structure
+(and using the same names) as the tree under the source directory. In
+the example, you'd find the Sun 4 library `libiberty.a' in the
+directory `gdb-sun4/libiberty', and GDB itself in `gdb-sun4/gdb'.
+
+ One popular reason to build several GDB configurations in separate
+directories is to configure GDB for cross-compiling (where GDB runs on
+one machine--the host--while debugging programs that run on another
+machine--the target). You specify a cross-debugging target by giving
+the `--target=TARGET' option to `configure'.
+
+ When you run `make' to build a program or library, you must run it
+in a configured directory--whatever directory you were in when you
+called `configure' (or one of its subdirectories).
+
+ The `Makefile' generated by `configure' for each source directory
+also runs recursively. If you type `make' in a source directory such
+as `gdb-4.7' (or in a separate configured directory configured with
+`--srcdir=PATH/gdb-4.7'), you will build all the required libraries,
+then build GDB.
+
+ When you have multiple hosts or targets configured in separate
+directories, 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.
+
+
+Specifying Names for Hosts and Targets
+=======================================
+
+ The specifications used for hosts and targets in the `configure'
+script are based on a three-part naming scheme, but some short
+predefined aliases are also supported. The full naming scheme encodes
+three pieces of information in the following pattern:
+
+ ARCHITECTURE-VENDOR-OS
+
+ For example, you can use the alias `sun4' as a HOST argument or in a
+`--target=TARGET' option, but the equivalent full name is
+`sparc-sun-sunos4'.
+
+ The `configure' script accompanying GDB does not provide any query
+facility to list all supported host and target names or aliases.
+`configure' calls the Bourne shell script `config.sub' to map
+abbreviations to full names; you can read the script, if you wish, or
+you can use it to test your guesses on abbreviations--for example:
+
+ % sh config.sub sun4
+ sparc-sun-sunos411
+ % sh config.sub sun3
+ m68k-sun-sunos411
+ % sh config.sub decstation
+ mips-dec-ultrix42
+ % sh config.sub hp300bsd
+ m68k-hp-bsd
+ % sh config.sub i386v
+ i386-unknown-sysv
+ % sh config.sub i786v
+ Invalid configuration `i786v': machine `i786v' not recognized
+
+`config.sub' is also distributed in the GDB source directory
+(`gdb-4.7', for version 4.7).
+
+
+`configure' Options
+====================
+
+ Here is a summary of the `configure' options and arguments that are
+most often useful for building GDB. `configure' also has several other
+options not listed here. *note : (configure.info)What Configure Does,
+for a full explanation of `configure'.
+
+ configure [--help]
+ [--prefix=DIR]
+ [--srcdir=PATH]
+ [--norecursion] [--rm]
+ [--target=TARGET] HOST
+
+You may introduce options with a single `-' rather than `--' if you
+prefer; but you may abbreviate option names if you use `--'.
+
+`--help'
+ Display a quick summary of how to invoke `configure'.
+
+`-prefix=DIR'
+ Configure the source to install programs and files under directory
+ `DIR'.
+
+`--srcdir=PATH'
+ *Warning: using this option requires GNU `make', or another `make'
+ that implements the `VPATH' feature.*
+ Use this option to make configurations in directories separate
+ from the GDB source directories. Among other things, you can use
+ this to build (or maintain) several configurations simultaneously,
+ in separate directories. `configure' writes configuration
+ specific files in the current directory, but arranges for them to
+ use the source in the directory PATH. `configure' will create
+ directories under the working directory in parallel to the source
+ directories below PATH.
+
+`--norecursion'
+ Configure only the directory level where `configure' is executed;
+ do not propagate configuration to subdirectories.
+
+`--rm'
+ Remove the configuration that the other arguments specify.
+
+`--target=TARGET'
+ Configure GDB for cross-debugging programs running on the specified
+ TARGET. Without this option, GDB is configured to debug programs
+ that run on the same machine (HOST) as GDB itself.
+
+ There is no convenient way to generate a list of all available
+ targets.
+
+`HOST ...'
+ Configure GDB to run on the specified HOST.
+
+ There is no convenient way to generate a list of all available
+ hosts.
+
+`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
+=======================
+
+GDB provides some support for debugging C++ progams. Partial Modula-2
+support is now in 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 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 has
+better kernel debugging, but the UC lawyers won't let FSF have it.
+
+
+Remote debugging
+=================
+
+The files m68k-stub.c, i386-stub.c, and sparc-stub.c are examples of
+remote stubs to be used with remote.c. They are designed to run
+standalone on a 68k, 386, or SPARC 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).
+Some working remote interfaces for talking to existing ROM monitors
+are:
+ remote-eb.c AMD 29000 "EBMON"
+ remote-hms.c Hitachi Micro Systems H8/300 monitor
+ remote-nindy.c Intel 960 "Nindy"
+ remote-adapt.c AMD 29000 "Adapt"
+ remote-mm.c AMD 29000 "minimon"
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.
-About reporting bugs...
-The correct address for reporting bugs found with gdb is
-"bug-gdb@prep.ai.mit.edu". Please email all bugs to that address.
+Reporting Bugs
+===============
-About xgdb...
+The correct address for reporting bugs found in gdb is
+"bug-gdb@prep.ai.mit.edu". Please email all bugs to that address.
+Please include the GDB version number (e.g. gdb-4.7), and how
+you configured it (e.g. "sun4" or "mach386 host, i586-intel-synopsys
+target").
+
+A known bug:
+
+ * If you run with a watchpoint enabled, breakpoints will become
+ erratic and might not stop the program. Disabling or deleting the
+ watchpoint will fix the problem.
+
+GDB can produce warnings about symbols that it does not understand. By
+default, these warnings are disabled. You can enable them by executing
+`set complaint 10' (which you can put in your ~/.gdbinit if you like).
+I recommend doing this if you are working on a compiler, assembler,
+linker, or gdb, since it will point out problems that you may be able
+to fix. Warnings produced during symbol reading indicate some mismatch
+between the object file and GDB's symbol reading code. In many cases,
+it's a mismatch between the specs for the object file format, and what
+the compiler actually outputs or the debugger actually understands.
+
+If you port gdb to a new machine, please send the required changes to
+bug-gdb@prep.ai.mit.edu. There's lots of information about doing your
+own port in the file gdb-4.7/gdb/doc/gdbint.texinfo, which you can
+print out, or read with `info' (see the Makefile.in there). 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' below.
+
+
+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...
-
-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 that express information
-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.
-
-About writing code for GDB...
+
+Writing Code for GDB
+=====================
+
+Documentation about GDB's internals is in the subdirectory doc, as
+`gdbint.texinfo'. In particular, there is a `cookbook' there on how
+to port GDB to a new machine. You can read it by hand, print it
+by using TeX and texinfo, or process it into an `info' file for use
+with Emacs' info mode or the standalone `info' program.
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
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
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 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.
+
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
in a header file (e.g. #ifdef TIOCSETP), *please* make sure that you
have #include'd the relevant header file in that module!
+There is a list of all known `feature-test macros' in gdbint.texinfo.
+Each such macro should be defined (or left undefined) in a host-dependent,
+target-dependent, or native-dependent include file. Not all of the
+macros are cleanly separated this way, yet. As you make changes, move
+the code toward cleanliness.
+
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,
the necessary changes throughout all the code in dbxread.c that
currently assumes BSD format.
+When generalizing GDB along a particular interface, please use an
+attribute-struct rather than inserting tests or switch statements
+everywhere. For example, GDB has been generalized to handle multiple
+kinds of remote interfaces -- not by #ifdef's everywhere, but by
+defining the "target_ops" structure and having a current target (as
+well as a stack of targets below it, for memory references). Whenever
+something needs to be done that depends on which remote interface we
+are using, a flag in the current target_ops structure is tested (e.g.
+`target_has_stack'), or a function is called through a pointer in the
+current target_ops structure. In this way, when a new remote interface
+is added, only one module needs to be touched -- the one that actually
+implements the new remote interface. Other examples of
+attribute-structs are BFD access to multiple kinds of object file
+formats, or GDB's access to multiple source languages.
+
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
+==========================
+
+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 the gdb source 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.
+
+I strongly recommend printing out the reference card and using it.
+Send reference-card suggestions to bug-gdb@prep.ai.mit.edu, just like bugs.
-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 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.
-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.
+Also, make sure that you've either compiled gdb with your local cc, or
+have run `fixincludes' if you are compiling with gcc.
\f
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