From: Paul Brook <paul@codesourcery.com>
To: qemu-devel@nongnu.org
Cc: Avi Kivity <avi@redhat.com>,
Andre Przywara <andre.przywara@amd.com>,
aliguori@us.ibm.com, kvm@vger.kernel.org
Subject: Re: [Qemu-devel] Re: [PATCH 1/2] allow hypervisor CPUID bit to be overriden
Date: Tue, 23 Jun 2009 12:31:12 +0100 [thread overview]
Message-ID: <200906231231.15206.paul@codesourcery.com> (raw)
In-Reply-To: <4A40A7EC.8070100@redhat.com>
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
WARNING: multiple messages have this Message-ID (diff)
From: Paul Brook <paul@codesourcery.com>
To: qemu-devel@nongnu.org
Cc: Andre Przywara <andre.przywara@amd.com>,
aliguori@us.ibm.com, Avi Kivity <avi@redhat.com>,
kvm@vger.kernel.org
Subject: Re: [Qemu-devel] Re: [PATCH 1/2] allow hypervisor CPUID bit to be overriden
Date: Tue, 23 Jun 2009 12:31:12 +0100 [thread overview]
Message-ID: <200906231231.15206.paul@codesourcery.com> (raw)
In-Reply-To: <4A40A7EC.8070100@redhat.com>
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
next prev parent reply other threads:[~2009-06-23 11:31 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-22 21:47 [PATCH 1/2] allow hypervisor CPUID bit to be overriden Andre Przywara
2009-06-22 21:47 ` [Qemu-devel] " Andre Przywara
2009-06-23 10:01 ` Avi Kivity
2009-06-23 10:01 ` [Qemu-devel] " Avi Kivity
2009-06-23 11:31 ` Paul Brook [this message]
2009-06-23 11:31 ` Paul Brook
2009-06-23 11:35 ` Avi Kivity
2009-06-23 11:35 ` Avi Kivity
2009-06-23 11:43 ` Paul Brook
2009-06-23 11:43 ` Paul Brook
2009-06-24 21:20 ` Jamie Lokier
2009-06-24 21:20 ` Jamie Lokier
2009-06-25 5:23 ` Gleb Natapov
2009-06-25 5:23 ` Gleb Natapov
2009-06-23 12:37 ` [PATCH 1/2 v2] " Andre Przywara
2009-06-23 12:37 ` [Qemu-devel] " Andre Przywara
2009-06-23 14:17 ` Anthony Liguori
2009-06-23 14:17 ` [Qemu-devel] " Anthony Liguori
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