[Pkg-xen-devel] Bug#649349: Bug#649349: xen-hypervisor-4.1-amd64: pygrub fails due to invalid opcode trapped

[Ian Campbell]

On Wed, 2011-11-23 at 14:08 +0000, Ian Campbell wrote:
> 
> The Intel manuals[0] suggest (in section 13.5 "DETECTION OF AVX
> INSTRUCTIONS") that the appropriate sequence to use from userspace to
> detect AVX is:
>      1. Detect CPUID.1:ECX.OSXSAVE[bit 27] = 1 (XGETBV enabled for
>         application use1)
>      2. Issue XGETBV and verify that XCR0[2:1] = ‘11b’ (XMM state and
>         YMM state are enabled by OS).
>      3. detect CPUID.1:ECX.AVX[bit 28] = 1 (AVX instructions
> supported).
> 
> glibc currently only does #3.
> 
> If I am right then using "noxsave" on native should demonstrate the
> issue as well and show that there is a bug in libc. 

Which seems to already be reported and fixed upstream:
http://sourceware.org/bugzilla/show_bug.cgi?id=13007
as well as against glibc in Debian http://bugs.debian.org/646549. The
fix is fixed in glibc-package SVN so ought to be fixed with the next
upload (2.13-22).

Cheers,
Ian.

-- 
Ian Campbell
Current Noise: Callenish Circle - My Hate Unfolds

Of course you have a purpose -- to find a purpose.