[Xen-devel] Re: xen drivers to use virtio?

[Anthony Liguori <anthony@xxxxxxxxxxxxx>]

Anthony Liguori wrote:
> Jeremy Fitzhardinge wrote:
> > Jun Koi wrote:
> > > If I understand correctly, we are going to rewrite some xen drivers in
> > > Linux kernel to use virtio once virtio is stable. Is that true?
> > >   
> > There are no plans to do so.
> Actually, they're already there to some degree now that qemu-dm is 
> tracking the upstream QEMU tree.  virtio support has been in the QEMU 
> tree for some time now.  If it's not enabled in qemu-dm by default, it 
> should be trivial to enable.
Apparently qemu-dm is still on an older SVN version of QEMU that doesn't 
have virtio.  I think Ian is still trying to work out the merge 
conflicts from Stefano's DisplayState refactoring.
In the mean time, it should be easy enough to port the virtio code into 
Ian's tree or just wait for him to rebase to a newer QEMU version.
Regards,

Anthony Liguori

> From Xend's perspective, virtio devices 
> shouldn't be different from either rtl8139, e1000, etc.  It's just 
> another PCI device.
> This model makes less sense in the context of stub domains, but if 
> you're running qemu-dm in dom0, you may actually get reasonable 
> performance out of the virtio drivers.
> In fact, comparing an HVM domain using virtio with qemu-dm in dom0 
> verses netfront ala PV-on-HVM would make for a very interesting comparison.
> And assuming PV-on-HVM isn't in upstream Linux yet (that appears to be 
> the case) and virtio is, it may even be a practical thing to do.
> Regards,
>
> Anthony Liguori
>
>
> >    J

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