README_PACKAGERS

1 July 2002

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.


-- (Unfortunate but true) When you configure to build with the 
   --prefix=/foo/bar/xyzzy option, the prefix /foo/bar/xyzzy gets
   baked into valgrind.so.  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 valgrind.so or libpthread.so.
   Valgrind will still work if you do, but it 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().  If valgrind.so was stripped the message would look like
   this:

   Mismatched free() / delete / delete []
      at 0x40043249: (inside valgrind.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 valgrind.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.


-- Try and ensure that the /usr/include/asm/unistd.h file on the
   build machine contains an entry for all the system calls that
   the kernels on the target machines can actually support.  On my
   Red Hat 7.2 (kernel 2.4.9) box the highest-numbered entry is   
      #define __NR_fcntl64            221
   but I have heard of 2.2 boxes where it stops at 179 or so.

   Reason for this is that at build time, support for syscalls
   is compiled in -- or not -- depending on which of these __NR_*
   symbols is defined.  Problems arise when /usr/include/asm/unistd.h
   fails to give an entry for a system call which is actually 
   available in the target kernel.  In that case, valgrind will
   abort if asked to handle such a syscall.  This is despite the
   fact that (usually) valgrind's sources actually contain the
   code to deal with the syscall.

   Several people have reported having this problem.  So, please
   be aware of it.  If it's useful, the syscall wrappers are
   all done in vg_syscall_mem.c; you might want to have a little
   look in there.


-- Please test the final installation works by running it on
   something huge.  I suggest checking that it can start and
   exit successfully both Mozilla-1.0 and OpenOffice.org 1.0.
   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 --workaround-gcc296-bugs=yes mozilla

   valgrind -v --trace-children=yes --workaround-gcc296-bugs=yes soffice


If you find any more hints/tips for packaging, please let me know
(jseward@acm.org).  Thanks.