README

Release notes for Valgrind
~~~~~~~~~~~~~~~~~~~~~~~~~~
If you are building a binary package of Valgrind for distribution,
please read README_PACKAGERS.  It contains some important information.

If you are developing Valgrind, please read README_DEVELOPERS.  It contains
some useful information.

For instructions on how to build/install, see the end of this file.

Valgrind works on most, reasonably recent Linux setups.  If you have
problems, consult FAQ.txt to see if there are workarounds.

Executive Summary
~~~~~~~~~~~~~~~~~
Valgrind is a GPL'd system for debugging and profiling x86-Linux programs.
With the tools that come with Valgrind, you can automatically detect
many memory management and threading bugs, avoiding hours of frustrating
bug-hunting, making your programs more stable. You can also perform
detailed profiling to help speed up your programs.

The Valgrind distribution includes five tools: two memory error
detectors, a thread error detector, a cache profiler and a heap profiler.
Several other tools have been built with Valgrind.

To give you an idea of what Valgrind tools do, when a program is run
under the supervision of the first memory error detector tool, all reads
and writes of memory are checked, and calls to malloc/new/free/delete
are intercepted. As a result, it can detect problems such as:

   Use of uninitialised memory
   Reading/writing memory after it has been free'd
   Reading/writing off the end of malloc'd blocks
   Reading/writing inappropriate areas on the stack
   Memory leaks -- where pointers to malloc'd blocks are lost forever
   Passing of uninitialised and/or unaddressible memory to system calls
   Mismatched use of malloc/new/new [] vs free/delete/delete []
   Overlaps of arguments to strcpy() and related functions
   Some abuses of the POSIX pthread API

Problems like these can be difficult to find by other means, often
lying undetected for long periods, then causing occasional,
difficult-to-diagnose crashes.  When one of these errors occurs, you can
attach GDB to your program, so you can poke around and see what's going
on.

Valgrind is closely tied to details of the CPU, operating system and
to a less extent, compiler and basic C libraries. This makes it
difficult to make it portable, so I have chosen at the outset to
concentrate on what I believe to be a widely used platform: x86/Linux.

Valgrind is licensed under the GNU General Public License, version 2. 
Read the file COPYING in the source distribution for details.


Documentation
~~~~~~~~~~~~~
A comprehensive user guide is supplied.  Point your browser at
$PREFIX/share/doc/valgrind/manual.html, where $PREFIX is whatever you
specified with --prefix= when building.


Building and installing it
~~~~~~~~~~~~~~~~~~~~~~~~~~
To install from CVS :

  0. Check out the code from CVS, following the instructions at
     http://developer.kde.org/source/anoncvs.html. The 'modulename' is
     "valgrind".

  1. cd into the source directory.

  2. Run ./autogen.sh to setup the environment (you need the standard
     autoconf tools to do so).

To install from a tar.bz2 distribution:

  3. Run ./configure, with some options if you wish. The standard
     options are documented in the INSTALL file.  The only interesting
     one is the usual --prefix=/where/you/want/it/installed.

  4. Do "make".

  5. Do "make install", possibly as root if the destination permissions
     require that.

  6. See if it works.  Try "valgrind --tool=memcheck ls -l".  Either
     this works, or it bombs out with some complaint.  In that case,
     please let us know (see valgrind.kde.org/bugs.html).

Important!  Do not move the valgrind installation into a place
different from that specified by --prefix at build time.  This will
cause things to break in subtle ways, mostly when Valgrind handles
fork/exec calls.


Julian Seward (jseward@acm.org)
Nick Nethercote (njn@valgrind.org)
Jeremy Fitzhardinge (jeremy@goop.org)