Bug 9616

Summary:	[PATCH] Fix buggy MMX check for non-SSE AMD cpus
Product:	liboil	Reporter:	Dan Williams <dcbw>
Component:	unknown	Assignee:	David Schleef <ds>
Status:	RESOLVED WORKSFORME	QA Contact:	David Schleef <ds>
Severity:	normal
Priority:	high	Keywords:	patch
Version:	unspecified
Hardware:	x86 (IA32)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:

Description Dan Williams 2007-01-11 11:08:23 UTC

See X.org bug #9614:

http://bugs.freedesktop.org/show_bug.cgi?id=9614

The copied Xorg fb code in liboil doesn't correctly detect the presence of MMX
and MMX extensions on AMD and AMD Geode processors.  Patch in that xorg bug
fixes the issue.

Comment 1 David Schleef 2007-02-13 18:45:33 UTC

I don't think that patch is correct.  As I understand it, CPUs that have the vendor string "Geode by NSC" do not have the AMD cpuid extensions, nor do they have mmxext.  There are, however, processors labelled "Geode" that do not use the vendor string "Geode by NSC".

Comment 2 Dan Williams 2008-03-13 06:42:23 UTC

(In reply to comment #1)
> I don't think that patch is correct.  As I understand it, CPUs that have the
> vendor string "Geode by NSC" do not have the AMD cpuid extensions, nor do they
> have mmxext.  There are, however, processors labelled "Geode" that do not use
> the vendor string "Geode by NSC".

Not correct; the patch actually came from AMD's Jordan Crouse.  The Geode GX2 and Geode LX (both used on OLPC XO laptops for example) are reported as "Geode by NSC" yet they certainly do have MMX.

For example, on a Geode GX2, /proc/cpuinfo says:

vendor_id: Geode by NSC
flags: fpu de pse tsc msr cx8 pge cmov mmx mmxext 3dnowext 3dnow

This is also definitely the case for the LX.

Comment 3 David Schleef 2008-03-13 12:10:30 UTC

Liboil on the XO detects "cmov mmx mmxext 3dnow 3dnowext".  This appears to be correct according to /proc/cpuinfo.

Comment 4 Corbin Simpson 2010-03-27 05:12:55 UTC

Tagging patch; will triage later.

...As this isn't an Xorg-related bug, maybe the people pinged by this comment could handle it?

Comment 5 David Schleef 2010-03-28 13:40:12 UTC

As mentioned in an earlier comment, this bug is unreproducable.

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