[libvirt] [PATCH 4/4] qemu: default to kvm32/kvm64 when KVM is enabled

Daniel P. Berrange berrange at redhat.com
Mon Jan 23 16:30:04 UTC 2012


On Mon, Jan 23, 2012 at 05:23:32PM +0100, Paolo Bonzini wrote:
> On 01/23/2012 05:03 PM, Daniel P. Berrange wrote:
> >>>>  >  The qemu32/qemu64 models are weird in that the exact combination of
> >>>>  >  CPUID flags does not match any actual processor.  kvm32 and kvm64 are
> >>>>  >  a better match when not using TCG.  Use them when -cpu is only needed
> >>>>  >  to hardcode a 32-bit guest arch or for kvmclock.
> >>>
> >>>  I don't think we can do this as it means the guest CPU may change unexpectedly
> >>>  for existing domains. A 32b domain started on current libvirt would see qemu32,
> >>>  while the same domain started after this patch would see kvm32.
> >Also, IIUC,  kvm32 is a fairly newly introduced CPU type for KVM - ie most
> >deployments of KVM won't support it.
> 
> Ok, I'll redo this patch with just kvm64.  As the wrong subject in
> 0/3 show, it was an afterthought.

Is kvm64 actually any more widely supported than kvm32 ? I though they
were all fairly new.

If I'm wrong, then we could trivially provide a kvm32, by using the
kvm64 model, and subtracting the the "long mode" CPU flag.

Daniel
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