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Re: [Xen-users] pv_ops dom0 kernel and VT cpu extensions

To: "Fajar A. Nugraha" <fajar@xxxxxxxxx>
Subject: Re: [Xen-users] pv_ops dom0 kernel and VT cpu extensions
From: Pasi Kärkkäinen <pasik@xxxxxx>
Date: Tue, 29 Dec 2009 18:09:18 +0200
Cc: Gerry Reno <greno@xxxxxxxxxxx>, xen-users@xxxxxxxxxxxxxxxxxxx
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On Tue, Dec 29, 2009 at 11:24:17AM +0700, Fajar A. Nugraha wrote:
> On Tue, Dec 29, 2009 at 11:01 AM, Gerry Reno <greno@xxxxxxxxxxx> wrote:
> > As physical boxes gain more and more processing capability it makes no sense
> > to restrict a physical machine to only a single hypervisor.
> >
> > Libvirt will support nested VM's that pass through the VT capabilities to
> > the next level.  So it makes sense that Xen should be able to do the same
> > thing and pass through the cpu VT capabilities to other hypervisors.  Is
> > there some law of the universe that prevents this?
> While KVM could probably do it, Xen currently can't. You might be able
> to get more answers about "why" and possible time line to support it
> (if any available) from xen-devel.

There was discussion about 'nested virtualization' with Xen at the
latest Xen Summit iirc.

That still doesn't mean dom0 should have VT visible to it. in Xen world 
dom0 is just a PV (paravirtualized) virtual machine guest, 
so you can't run KVM in dom0. 

If you want to run KVM under Xen HVM guest, then that should be
possible when 'nested virtualization' is supported in Xen.

-- Pasi

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