README_PACKAGERS

Greetings, packaging person!  This information is aimed at people
building binary distributions of Valgrind.

Thanks for taking the time and effort to make a binary distribution of
Valgrind.  The following notes may save you some trouble.

-- If your toolchain (compiler, linker) support lto, using the configure
   option --enable-lto=yes will produce a smaller/faster valgrind
   (up to 10%).

-- Do not ship your Linux distro with a completely stripped
   /lib/ld.so.  At least leave the debugging symbol names on -- line
   number info isn't necessary.  If you don't want to leave symbols on
   ld.so, alternatively you can have your distro install ld.so's
   debuginfo package by default, or make ld.so.debuginfo be a
   requirement of your Valgrind RPM/DEB/whatever.

   Reason for this is that Valgrind's Memcheck tool needs to intercept
   calls to, and provide replacements for, some symbols in ld.so at
   startup (most importantly strlen).  If it cannot do that, Memcheck
   shows a large number of false positives due to the highly optimised
   strlen (etc) routines in ld.so.  This has caused some trouble in
   the past.  As of version 3.3.0, on some targets (ppc32-linux,
   ppc64-linux), Memcheck will simply stop at startup (and print an
   error message) if such symbols are not present, because it is
   infeasible to continue.

   It's not like this is going to cost you much space.  We only need
   the symbols for ld.so (a few K at most).  Not the debug info and
   not any debuginfo or extra symbols for any other libraries.


-- (Unfortunate but true) When you configure to build with the
   --prefix=/foo/bar/xyzzy option, the prefix /foo/bar/xyzzy gets
   baked into valgrind.  The consequence is that you _must_ install
   valgrind at the location specified in the prefix.  If you don't,
   it may appear to work, but will break doing some obscure things,
   particularly doing fork() and exec().

   So you can't build a relocatable RPM / whatever from Valgrind.


-- Don't strip the debug info off lib/valgrind/$platform/vgpreload*.so
   in the installation tree.  Either Valgrind won't work at all, or it
   will still work if you do, but will generate less helpful error
   messages.  Here's an example:

   Mismatched free() / delete / delete []
      at 0x40043249: free (vg_clientfuncs.c:171)
      by 0x4102BB4E: QGArray::~QGArray(void) (tools/qgarray.cpp:149)
      by 0x4C261C41: PptDoc::~PptDoc(void) (include/qmemarray.h:60)
      by 0x4C261F0E: PptXml::~PptXml(void) (pptxml.cc:44)
      Address 0x4BB292A8 is 0 bytes inside a block of size 64 alloc'd
      at 0x4004318C: __builtin_vec_new (vg_clientfuncs.c:152)
      by 0x4C21BC15: KLaola::readSBStream(int) const (klaola.cc:314)
      by 0x4C21C155: KLaola::stream(KLaola::OLENode const *) (klaola.cc:416)
      by 0x4C21788F: OLEFilter::convert(QCString const &) (olefilter.cc:272)

   This tells you that some memory allocated with new[] was freed with
   free().

   Mismatched free() / delete / delete []
      at 0x40043249: (inside vgpreload_memcheck.so)
      by 0x4102BB4E: QGArray::~QGArray(void) (tools/qgarray.cpp:149)
      by 0x4C261C41: PptDoc::~PptDoc(void) (include/qmemarray.h:60)
      by 0x4C261F0E: PptXml::~PptXml(void) (pptxml.cc:44)
      Address 0x4BB292A8 is 0 bytes inside a block of size 64 alloc'd
      at 0x4004318C: (inside vgpreload_memcheck.so)
      by 0x4C21BC15: KLaola::readSBStream(int) const (klaola.cc:314)
      by 0x4C21C155: KLaola::stream(KLaola::OLENode const *) (klaola.cc:416)
      by 0x4C21788F: OLEFilter::convert(QCString const &) (olefilter.cc:272)

   This isn't so helpful.  Although you can tell there is a mismatch, 
   the names of the allocating and deallocating functions are no longer
   visible.  The same kind of thing occurs in various other messages 
   from valgrind.


-- Don't strip symbols from lib/valgrind/* in the installation tree.
   Doing so will likely cause problems.  Removing the line number info is
   probably OK (at least for some of the files in that directory), although
   that has not been tested by the Valgrind developers.


-- Please test the final installation works by running it on something
   huge.  I suggest checking that it can start and exit successfully
   both Firefox and OpenOffice.org.  I use these as test programs, and I
   know they fairly thoroughly exercise Valgrind.  The command lines to use
   are:

   valgrind -v --trace-children=yes firefox

   valgrind -v --trace-children=yes soffice


If you find any more hints/tips for packaging, please report
it as a bugreport. See http://www.valgrind.org for details.