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Subject: Re: [Qemu-devel] [PATCH v2 0/3] target-i386: Don't trigger CPUID
 warnings by default in KVM mode (in most hosts)
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To: Eduardo Habkost <ehabkost@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>, Richard Henderson <rth@twiddle.net>, qemu-devel@nongnu.org, "Dr. David Alan Gilbert" <dgilbert@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>



On 03/11/2015 23:54, Eduardo Habkost wrote:
> Probably, yes. libvirt even has these commented out in their cpu_map.xml:
> 
>     <model name='qemu64'>
>       <model name='kvm64'/>
>       <!-- These are supported only by TCG.  KVM supports them only if the
>            host does.  So we leave them out:
> 
>            <feature name='popcnt'/>
>            <feature name='lahf_lm'/>
>            <feature name='sse4a'/>
>            <feature name='abm'/>
>       -->
>       <feature name='svm'/>
>     </model>
> 
> (libvirt must stop making assumptions about the CPU model feature sets so
> all <feature> elements in cpu_map.xml should go away. But at least the
> current cpu_map.xml is a good reference to what it expects today.)

FWIW, lahf_lm is present on virtually all 64-bit machines and is rare
enough that KVM could just emulate it, so we shouldn't remove it.  But
removing popcnt is a good suggestion to take from libvirt.  It can be
done on top of this series.  We should get all of this into the first
-rc, anyway.

Paolo