		      README for gdb-4.10 release
		    Updated 13-Aug-93 by Fred Fish

This is GDB, the GNU source-level debugger, presently running under un*x.  A
summary of new features is in the file `NEWS'.


Unpacking and Installation -- quick overview
==========================

   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-4.10 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.

   When you unpack the gdb-4.10.tar.gz or gdb-4.10.tar.gz file, you'll find a
directory called `gdb-4.10', which contains:

  Makefile.in      config.sub*      glob/            opcodes/
  README           configure*       include/         readline/
  bfd/             configure.in     libiberty/       texinfo/
  config/          etc/             mmalloc/
  config.guess*    gdb/             move-if-change*

To build GDB, you can just do:

	cd gdb-4.10
	./configure
	make
	cp gdb/gdb /usr/local/bin/gdb	(or wherever you want)

   This will configure and build all the libraries as well as GDB.  If
`configure' can't determine your system type, specify one as its argument,
e.g. sun4 or decstation.

   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.


More Documentation
******************

   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-4.10/gdb/refcard.ps'.)  If you can use PostScript
or GhostScript with your printer, you can print the reference card immediately
with `refcard.ps'.

   The release also includes the source for the reference card.  You can
format it, using TeX, by typing:

     make refcard.dvi

   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.

   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.

   If you want to format these Info files yourself, you need one of the Info
formatting programs, such as `texinfo-format-buffer' or `makeinfo'.

   If you have `makeinfo' installed, and are in the top level GDB source
directory (`gdb-4.10', in the case of version 4.10), you can make the Info
file by typing:

     cd gdb
     make gdb.info

   If you want to typeset and print copies of this manual, you need TeX, a
program to print its DVI output files, and `texinfo.tex', the Texinfo
definitions file.

   TeX is a 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 (for PostScript devices) 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-4.10/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 `gdb' 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 4.10 distribution is in the `gdb-4.10'
directory.  That directory contains:

`gdb-4.10/configure (and supporting files)'
     script for configuring GDB and all its supporting libraries.

`gdb-4.10/gdb'
     the source specific to GDB itself

`gdb-4.10/bfd'
     source for the Binary File Descriptor library

`gdb-4.10/include'
     GNU include files

`gdb-4.10/libiberty'
     source for the `-liberty' free software library

`gdb-4.10/opcodes'
     source for the library of opcode tables and disassemblers

`gdb-4.10/readline'
     source for the GNU command-line interface

`gdb-4.10/glob'
     source for the GNU filename pattern-matching subroutine

`gdb-4.10/mmalloc'
     source for the GNU memory-mapped malloc package

'gdb-4.10/sim'
     source for some simulators (z8000, H8/300, H8/500, etc)

   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-4.10'
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-4.10
     ./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-4.10' source directory
for version 4.10, `configure' creates configuration files for every directory
level underneath (unless you tell it not to, with the `--norecursion' option).

   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 4.10, type the following to configure only the
`bfd' subdirectory:

     cd gdb-4.10/bfd
     ../configure HOST

   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.


Compiling GDB in another directory
==================================

   If you want to run GDB versions for several host or target machines, you
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 correctly (GNU `make' and
SunOS 'make' are two that should), running `make' in each of these directories
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 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 4.10, you can build GDB in a separate directory
for a Sun 4 like this:

     cd gdb-4.10
     mkdir ../gdb-sun4
     cd ../gdb-sun4
     ../gdb-4.10/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' that `configure' generates in each source directory also
runs recursively.  If you type `make' in a source directory such as `gdb-4.10'
(or in a separate configured directory configured with
`--srcdir=PATH/gdb-4.10'), you will build all the required libraries, and 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.  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-4.10', for
version 4.10).


`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 compatibly 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++ programs, however that support
only works well with GNU C++, and even then only on systems that use stabs
debugging format.  In particular, cfront based compilers such as Sun's C++ are
not fully supported.

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.

Pascal programs which use sets, subranges, file variables, or nested functions
will not currently work.

Partial Modula-2 and Chill support is now in GDB.


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 an
m68k, i386, 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.

Some working remote interfaces for talking to existing ROM monitors are:

	remote-adapt.c	 AMD 29000 "Adapt"
	remote-eb.c	 AMD 29000 "EBMON"
	remote-es1800.c	 Ericsson 1800 monitor
	remote-hms.c	 Hitachi Micro Systems H8/300 monitor
	remote-mips.c	 MIPS remote debugging protocol
	remote-mm.c	 AMD 29000 "minimon"
	remote-nindy.c   Intel 960 "Nindy"
	remote-sim.c	 Generalized simulator protocol
	remote-st2000.c	 Tandem ST-2000 monitor
	remote-udi.c	 AMD 29000 using the AMD "Universal Debug Interface"
	remote-vx.c	 VxWorks realtime kernel
	remote-z8k.c	 Zilog Z8000 simulator

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.

Remote-udi.c and the 29k-share subdirectory contain a remote interface for AMD
29000 programs, which uses the AMD "Universal Debug Interface".  This allows
GDB to talk to software simulators, emulators, and/or bare hardware boards,
via network or serial interfaces.  Note that GDB only provides an interface
that speaks UDI, not a complete solution.  You will need something on the
other end that also speaks UDI.


Reporting Bugs
===============

The correct address for reporting bugs found in gdb is
"bug-gdb@prep.ai.mit.edu".  Please email all bugs, and all requests for help
with GDB, to that address.  Please include the GDB version number (e.g.
gdb-4.10), and how you configured it (e.g. "sun4" or "mach386 host,
i586-intel-synopsys target").  If you include the banner that GDB prints when
it starts up, that will give us enough information.

For more information on how/whether to report bugs, see the GDB Bugs section
of the GDB manual (gdb/doc/gdb.texinfo).

Known bugs:

  * Under Ultrix 4.2 (DECstation-3100), we have seen problems with backtraces
    after interrupting the inferior out of a read().  The problem is caused by
    ptrace() returning an incorrect value for register 30.  As far as we can
    tell, this is a kernel problem.  Any help with this would be greatly
    appreciated.

  * On the SPARC GDB reports incorrect values of struct arguments to
    functions, for the seventh and subsequent arguments.  We have been looking
    at this but no fix is available yet.

  * On DECstations there are warnings about shift counts out of range in
    various BFD modules.  None of them is a cause for alarm, they are actually
    a result of bugs in the DECstation compiler.

  * On Solaris using the "run" command when the program is already running
    restarts the program, but may leave a core dump from the previous
    execution in the current directory.  Other SVR4 based systems don't seem
    to have this problem, using the same gdb source code.

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.


X Windows versus GDB
=====================

There is an "xxgdb", which seems to work for simple operations, which was
posted to comp.sources.x.

For those interested 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.


Writing Code for GDB
=====================

There is a lot of information about writing code for GDB in the internals
manual, distributed with GDB in gdb/doc/gdbint.texinfo.  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.  In particular,
see the nodes Getting Started, Debugging GDB, New Architectures, Coding Style,
Clean Design, and Submitting Patches.

If you are pondering writing anything but a short patch, especially take note
of the information about copyrights in the node Submitting Patches.  It can
take quite a while to get all the paperwork done, so we encourage you to start
that process as soon as you decide you are planning to work on something, or
at least well ahead of when you think you will be ready to submit the patches.


GDB Testsuite
=============

There is a dejagnu based testsuite available for testing your newly built gdb,
or for regression testing gdb's with local modifications.  The testsuite is
distributed separately from the base gdb distribution for the convenience of
people that wish to get either gdb or the testsuite separately.

The name of the testsuite is gdb-4.10-testsuite.tar.gz.  You unpack it in the
same directory in which you unpacked the base gdb distribution, and it will
create and populate the directory gdb-4.10/gdb/testsuite.

Running the testsuite requires the prior installation of dejagnu, which should
be available via ftp.  Once dejagnu is installed, you can run the tests in one
of two ways:

  (1)	cd gdb-4.10/gdb		(assuming you also unpacked gdb)
	make check

or

  (2)	cd gdb-4.10/gdb/testsuite
	make		(builds the test executables)
	make site.exp	(builds the site specific file)
	runtest -tool gdb GDB=../gdb    (or GDB=<somepath> as appropriate)

The second method gives you slightly more control in case of problems with
building one or more test executables, in case you wish to remove some test
executables before running the tests, or if you are using the testsuite
'standalone', without it being part of the gdb source tree.

See the dejagnu documentation for further details.


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