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Re: [Qemu-devel] [PATCH] Qemu: Fix eax for cpuid leaf 0x40000000
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From: |
Eduardo Habkost |
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Subject: |
Re: [Qemu-devel] [PATCH] Qemu: Fix eax for cpuid leaf 0x40000000 |
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Date: |
Tue, 12 Aug 2014 16:29:52 -0300 |
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User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Tue, Aug 12, 2014 at 09:12:00PM +0200, Paolo Bonzini wrote:
> Il 12/08/2014 20:55, Eduardo Habkost ha scritto:
> > This makes the CPUID data change under the guest's feet during
> > live-migration.
> >
> > Adding compat code to ensure older machine-types keep the old behavior
> > is necessary, but in this specific case it is mostly harmless because
> > 0x0 is documented as being equivalent to 0x40000001.
> >
> > (But I don't know how guests are supposed to behave when they see
> > CPUID[KVM_CPUID_SIGNATURE_NEXT].EAX==0.)
>
> The only obvious thing to do would be to treat it as 0x40000101.
I just want to be sure the guests really do that. If we know guests
won't do anything different with the CPUID change, I won't mind having
no compat code for this.
--
Eduardo