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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [kvm-devel] [Qemu-devel] expose host CPU
	=?iso-8859-1?q?features=09to=09guests=3A_Take?= 3
Date: Tue, 25 Sep 2007 13:51:54 +0100
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To: qemu-devel@nongnu.org
Cc: kvm-devel <kvm-devel@lists.sourceforge.net>, "J. Mayer" <l_indien@magic.fr>

On Tuesday 25 September 2007, Avi Kivity wrote:
> J. Mayer wrote:
> > On Tue, 2007-09-25 at 11:01 +0200, Avi Kivity wrote:
> >> Dan Kenigsberg wrote:
> >>> On Tue, Sep 25, 2007 at 03:28:24AM +0200, andrzej zaborowski wrote:
> >>>> Hi,
> >>>>
> >>>> On 24/09/2007, Dan Kenigsberg <danken@qumranet.com> wrote:
> >>>>> As with previous "Takes" of this patch, its purpose is to expose host
> >>>>> +{
> >>>>> +    asm("cpuid"
> >>>>> +        : "=a" (*ax),
> >>>>> +          "=b" (*bx),
> >>>>> +          "=c" (*cx),
> >>>>> +          "=d" (*dx)
> >>>>> +        : "a" (function));
> >>>>> +}
> >>>>
> Indeed for regular qemu this is useless.  But it is useful for kqemu
> (for which there is support in mainline qemu), and for kvm (which we
> hope to merge one day).

And, as discussed before, it should be asking the hypervisor what features it 
supports instead of trying to guess from the cpuid output.

Paul