[Qemu-devel] Valgrinding QEMU

[Julian Seward]

As of today, the Valgrind 3 development line supports 
applications which use self-modifying code on x86 and amd64.
So it may now be possible to use Valgrind to debug/profile
an unmodified build of QEMU (at least the softmmu variants).  

See http://www.valgrind.org/devel/cvs_svn.html for details
of how to check out and build the 3 line -- it's easy.

If anybody tries this I would be interested to hear the results.

J


----------  Forwarded Message  ----------

Subject: [Valgrind-developers] valgrind: r4122 - trunk/coregrind
Date: Thursday 07 July 2005 11:05
From: address@hidden
To: address@hidden

Author: sewardj
Date: 2005-07-07 11:05:05 +0100 (Thu, 07 Jul 2005)
New Revision: 4122

Log:
Support for self modifying code on unfriendly platforms (x86, amd64)
via the use of self-checking translations.  (Friendly platforms which
have icache-invalidation instructions we can observe, such as ppc32,
are already handled correctly.)  This should finally fix the
longstanding problem of V incorrectly handling calls of statically
nested functions (a gcc extension), and more generally make it a lot
easier to use V to debug dynamic code generation systems.

Since self-checking is a large performance overhead, there is some
control via a command line flag:

   --smc-support=none

      Don't make any translations self-checking.

   --smc-support=stack

      Add checking code for translations taken from segments which
      have the SF_GROWDOWN flag set -- stacks, basically.
      This is the default.  It should make gcc nested functions and
      GNU Ada work correctly with no intervention from the user.

   --smc-support=all

      Make all translations self-checking.  This is expensive and
      you want to do this if you're debugging a JIT compiler or
      some such.

Modified:
   trunk/coregrind/m_main.c
   trunk/coregrind/m_options.c
   trunk/coregrind/m_translate.c
   trunk/coregrind/m_transtab.c
   trunk/coregrind/pub_core_options.h
   trunk/coregrind/pub_core_transtab.h

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