Re: [Xen-devel] vga passthrough with qemu-xen (or qemu upstream)

["Wu, Feng" <feng.wu@xxxxxxxxx>]

> -----Original Message-----
> From: Shakeel Butt [mailto:shakeel.butt@xxxxxxxxx]
> Sent: Wednesday, January 22, 2014 1:37 AM
> To: Pasi Kärkkäinen
> Cc: Wu, Feng; Gordan Bobic; G.R.; G.R.; xen-devel@xxxxxxxxxxxxx
> Subject: Re: [Xen-devel] vga passthrough with qemu-xen (or qemu upstream)
> 
> On Tue, Jan 21, 2014 at 4:55 AM, Pasi Kärkkäinen <pasik@xxxxxx> wrote:
> > Hello,
> >
> > On Mon, Jan 20, 2014 at 01:24:23PM +0000, Wu, Feng wrote:
> >>
> >>
> >> > >>> >
> >> > >>> > Hi all,
> >> > >>> >
> >> > >>> > Is it possible to do vga passthrough on xen-unstable with qemu-xen
> as
> >> > >>> > device model? I tried but I am getting error 'gfx_passthru' invalid
> >> > >>> > parameter for qemu-xen. I am able to do passthrough with qemu
> >> > >>> > traditional i.e. qemu-dm.
> >> > >>>
> >> > >>> As far as I know, only qemu-traditional supports vga pass-through
> >> > >>> right now.
> >> > >>
> >> > >> Right.
> >> > >> It is not possible to assign your primary VGA card to a VM with
> >> > >> qemu-xen. You should be able to assign your secondary VGA card
> though.
> >> > >
> >> > > Let me understand this correctly. If I have two VGA cards then I can
> >> > > passthrough
> >> > > secondary VGA card (in Dom0) to HVM as its primary VGA card. Is this
> >> > > right and
> >> > > if yes how can I do it?
> >> >
> >> > Passing any VGA card as a primary-in-domU has always been problematic.
> >>
> >> I think passing VGA card as a primary-in-domU works well in
> Qemu-traditional, right?
> >>
> >
> > primary-in-domU requires vendor specific hacks in Xen qemu.
> > qemu-traditional includes many patches for Intel IGD primary passthru
> support,
> > but patches for AMD/ATI and Nvidia GPUs aren't merged to qemu-traditional.
> >
> > There unapplied patches for qemu-traditional (AMD/Nvidia) GPU passthru are
> in
> > various source trees, mailinglist archives, and on some blogs around the
> internet.
> >
> > Also for Intel IGD I think there's at least one outstanding patch/fix that
> > hasn't been merged to qemu-traditional yet, see:
> >
> > http://lists.xenproject.org/archives/html/xen-devel/2013-02/msg00538.html
> > http://lists.xen.org/archives/html/xen-devel/2013-07/msg01385.html
> >
> > The patch in question probably needs some work before it is suitable for 
> > being
> applied to qemu-traditional.
> >
> Thanks for sharing. Just for the information, I was able to make
> Nvidia K2000 work
> in passthrough mode without any patch to qemu traditional.

Intel IGD pass-through also works well on Sandy bridge, Ivy bridge, HSW platform
with qemu-traditional.

Thanks,
Feng

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