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Date: Sat, 22 Aug 2009 02:03:35 +0100
From: Jamie Lokier <jamie@shareable.org>
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Subject: [Qemu-devel] Re: [PATCH] introduce kvm64 CPU
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To: Avi Kivity <avi@redhat.com>
Cc: Andre Przywara <andre.przywara@amd.com>, qemu-devel@nongnu.org, kvm@vger.kernel.org

Avi Kivity wrote:
> On 08/21/2009 12:34 AM, Andre Przywara wrote:
> >In addition to the TCG based qemu64 type let's introduce a kvm64 CPU type,
> >which is the least common denominator of all KVM-capable x86-CPUs
> >(based on Intel Pentium 4 Prescott). It can be used as a base type
> >for migration.
> >   
> 
> Typically users will want more specialized greatest common denomiator 
> cpu types; if a site has standardized on recent hardware they will want 
> the features of that hardware exposed.

My experience is of sites which don't standardise on hardware in that
way.  They standardise on suppliers, and buy whatever is available
when more hardware is needed, or reuse existing hardware which is made
redundant from some other purpose.

kvm64 is a good compromise for sites like that, because it should work
with everything that's 64-bit and capable of running KVM.  I expect
all "server" machines which can run KVM are 64-bit, and it's only
laptops which have 32-bit KVM-capable chips (but I'm not sure).

-- Jamie