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

[Shakeel Butt <shakeel.butt@xxxxxxxxx>]

On Mon, Jan 20, 2014 at 5:31 AM, Gordan Bobic <gordan@xxxxxxxxxx> wrote:
> On 2014-01-20 13:24, Wu, Feng wrote:
>>>
>>> -----Original Message-----
>>> From: xen-devel-bounces@xxxxxxxxxxxxx
>>> [mailto:xen-devel-bounces@xxxxxxxxxxxxx] On Behalf Of Gordan Bobic
>>> Sent: Monday, January 20, 2014 8:50 PM
>>> To: xen-devel@xxxxxxxxxxxxx
>>> Subject: Re: [Xen-devel] vga passthrough with qemu-xen (or qemu upstream)
>>>
>>> On 2014-01-20 12:31, Shakeel Butt wrote:
>>> > On Mon, Jan 20, 2014 at 4:09 AM, Stefano Stabellini
>>> > <stefano.stabellini@xxxxxxxxxxxxx> wrote:
>>> >> On Mon, 20 Jan 2014, Wu, Feng wrote:
>>> >>> > -----Original Message-----
>>> >>> > From: xen-devel-bounces@xxxxxxxxxxxxx
>>> >>> > [mailto:xen-devel-bounces@xxxxxxxxxxxxx] On Behalf Of Shakeel Butt
>>> >>> > Sent: Monday, January 20, 2014 1:48 PM
>>> >>> > To: xen-devel@xxxxxxxxxxxxx
>>> >>> > Subject: [Xen-devel] vga passthrough with qemu-xen (or qemu
>>> >>> > upstream)
>>> >>> >
>>> >>> > 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?
>
>
> I never managed to get it working - it certainly isn't just a matter of
> enabling the option. There is at least the matter of also side-loading
> the VGA BIOS, and IIRC that was limited to 64KB in size, which rules
> out all ATI and Nvidia GPUs of the past 2-3 generations.
>
> Having said that - I never found a particularly good use-case for
> primary passthrough. Once the GPU driver loads it works just the
> same for all intents and purposes.
>

I have successfully managed to passthrough VGA card as primary to DomU
with qemu traditional. I am trying to do the same with upstream qemu because
 I need some new features of the upstream qemu which are not available
in qemu traditional.

With qemu upstream I can passthrough as secondary VGA card to DomU
and able to see it in device manager in DomU (Windows 7) but Windows
couldn't use it and display some error that another card is being used as
display. I want Windows to use the passthroughed vga card  as its display.

Shakeel

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