On 09/10/09 14:24, Ralph Corderoy wrote:
On 09/10/09 13:53, Ralph Corderoy wrote:
Because Allegro is used, valgrind and cachegrind can't be used;
Allegro doesn't play nicely with them. :-(
What's the problem with valgrind and allegro?
$ valgrind ./rpcemu
==9782== Memcheck, a memory error detector.
==9782== Copyright (C) 2002-2007, and GNU GPL'd, by Julian Seward et al.
==9782== Using LibVEX rev 1804, a library for dynamic binary translation.
==9782== Copyright (C) 2004-2007, and GNU GPL'd, by OpenWorks LLP.
==9782== Using valgrind-3.3.0-Debian, a dynamic binary instrumentation
framework.
==9782== Copyright (C) 2000-2007, and GNU GPL'd, by Julian Seward et al.
==9782== For more details, rerun with: -v
==9782==
rpcemu: version=0.8.5 _DEBUG=no DYNAREC=yes
Shutting down Allegro due to signal #11
Ah. I think that's a rather unhelpful allegro message confusing you...
Allegro has registered a segv handler and prints that message whenever
the program hits a segv regardless of who causes it
If you use --trace-signals=yes on valgrind you'll see that the signal is
coming from dynamically generated code - the core problem is that
valgrind is itself doing dynamic translation and has a cache and if code
that it has translated changes it will not notice and it will execute
incorrect code.
Ad --smc-check=all to valgrind and it will checksum each block before
executing it and retranslate it if it has changed. That will slow things
down a lot though.
Better is to add VALGRIND_DISCARD_TRANSLATIONS() calls to the rpcemu
code so that it tells valgrind when it has reused a piece of the dynamic
code buffer and valgrind will then discard it's cached translations for
that area.
I also had to patch my way round one instruction that rcpemu is using in
the code it generates that valgrind didn't understand as it wasn't the
"normal" encoding for that instruction. I've raised a bug for valgrind
to get Julian to fix that:
https://bugs.kde.org/show_bug.cgi?id=209995
Tom
--
Tom Hughes ([email protected])
http://www.compton.nu/
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