[Valgrind-users] Re: [Valgrind-developers] Need testers for MMX support

[Jeremy F. <je...@go...>]

On Wed, 2003-03-26 at 13:30, Julian Seward wrote:

> Greetings, y'all.
> 
> I just committed to the cvs head, initial support for MMX instructions.
> Just MMX, not SSE or SSE2.  SSE and SSE2 are for later; a staged approach
> keeps the resulting code simpler and more maintainable (I hope).
> 
> Most MMX instructions now work.  What would be very useful is for
> people who have apps with MMX instructions, to check out and build the
> head [details below] and then run their MMXish apps on it.  There will 
> be initial breakage, but the sooner this is done, the sooner we will 
> have working MMX support :-)
> 
> So, can anyone help out?

I don't have much which uses MMX for anything other than a quick memcpy,
but I'll give it a spin.  SSE and 3DNOW are more likely to get used (may
even get the nvidia drivers doing something sane).

Unfortunately I suspect MMX instructions do frequently operate on
uninitialized data, so I'm not sure how far the MMX support as
implemented will go.  I wonder if its worthwhile having a CLO to
enable/disable MMX support?

And, um, cpuid hasn't been updated to advertise MMX:


: ixodes:pts/17; valgrind '--skin=none' x86info -a
==5099== Nulgrind, a binary JIT-compiler for x86-linux.
==5099== Copyright (C) 2002, and GNU GPL'd, by Nicholas Nethercote.
==5099== Using valgrind-1.9.4, a program instrumentation system for x86-linux.
==5099== Copyright (C) 2000-2002, and GNU GPL'd, by Julian Seward.
==5099== Estimated CPU clock rate is 1878 MHz
==5099== For more details, rerun with: -v
==5099==
x86info v1.11.  Dave Jones 2001, 2002
Feedback to <da...@su...>.

Need to be root to use specified options.
Found 1 CPU
eax in: 0x00000000, eax = 00000001 ebx = 756e6547 ecx = 6c65746e edx = 49656e69
eax in: 0x00000001, eax = 0000052b ebx = 00000000 ecx = 00000000 edx = 000001bf

Family: 5 Model: 2 Stepping: 11 Type: 0
CPU Model: Pentium 75-200 Original OEM
Feature flags:
 fpu vme de pse tsc msr mce cx8

Connector type: Socket 5/7 (296 Pin PGA)


1817.95 MHz processor (estimate).

==5099==


Cool!  A 1.8GHz P75!

This should fix it:

Index: coregrind/vg_helpers.S
===================================================================
RCS file: /cvsroot/valgrind/valgrind/coregrind/vg_helpers.S,v
retrieving revision 1.17
diff -u -r1.17 vg_helpers.S
--- coregrind/vg_helpers.S      14 Dec 2002 23:59:08 -0000      1.17
+++ coregrind/vg_helpers.S      26 Mar 2003 22:27:48 -0000
@@ -147,7 +147,7 @@
        movl    $0x52b, %eax
        movl    $0x0,   %ebx
        movl    $0x0,   %ecx
-       movl    $0x1bf, %edx
+       movl    $0x008001bf, %edx
        jmp     cpuid__99
 cpuid__0:
        movl    $0x1,        %eax




        J