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Re: [Qemu-devel] Re: [PATCH 1/2] allow hypervisor CPUID bit to be overri
From: |
Paul Brook |
Subject: |
Re: [Qemu-devel] Re: [PATCH 1/2] allow hypervisor CPUID bit to be overriden |
Date: |
Tue, 23 Jun 2009 12:31:12 +0100 |
User-agent: |
KMail/1.11.4 (Linux/2.6.29-2-amd64; KDE/4.2.4; x86_64; ; ) |
On Tuesday 23 June 2009, Avi Kivity wrote:
> On 06/23/2009 12:47 AM, Andre Przywara wrote:
> > KVM defaults to the hypervisor CPUID bit to be set, whereas pure QEMU
> > clears it. On some occasions one want to set or clear it the other way
> > round (for instance to get HyperV running inside a guest).
> > Allow the default to be overridden on the command line and fix some
> > whitespace damage on the way.
>
> It makes sense for qemu to set the hypervisor bit unconditionally. A
> guest running under qemu is not bare metal.
I see no reason why a guest has to be told that it's running inside a VM.
In principle an appropriately configured qemu should be indistinguishable from
real hardware. In practice it's technically infeasible to cover absolutely
everything, but if we set this bit we're not even trying.
I have no objection to the bit being set by default for the QEMU CPU types.
Paul
[Qemu-devel] [PATCH 1/2 v2] allow hypervisor CPUID bit to be overriden, Andre Przywara, 2009/06/23