Re: [Xen-devel] GPU passthrough with Xen 4.2 on Ubuntu 12.04

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Wed, Aug 08, 2012 at 02:26:33PM +0100, Matthew Dean wrote:
> 
>    I've used the stock Ubuntu provided kernel which is version
>    3.2.0-27-generic.  Dom0 is connected to a display via the intel integrated
>    graphics.
> 

You might want to try Linux 3.4.x or 3.5.x dom0 kernels aswell.
I think there has been some fixes in xen-pciback.


> 
>    When I boot the VM everything seems to work fine.  Windows picks up all
>    three devices and I can install drivers for them.  The USB controller
>    works flawlessly and I can use an attached mouse and keyboard.  The radeon
>    card requires a restart after which an attached display comes to life and
>    I have 3D acceleration.  Restarting the VM seems to work OK.  If however I
>    shut down the VM I have no end of problems.  On any subsequent startup the
>    vm struggles to get past the windows splash screen, waiting much longer
>    than usual.  During this period dom0 is sluggish regarding mouse and
>    keyboard input even though cpu and memory usage are very low.  When
>    windows finally loads I have no active display and I have to view the VM
>    via VNC.  In device manage I find that windows has disabled the GPU saying
>    there are not enough resources to run the card.  From this point onwards I
>    can do nothing to get the gpu working again aside from removing the
>    device, manually deleting the drivers, and starting again.
> 

Do you get any errors from Xen (xl dmesg), or from dom0 kernel (dmesg) ? 

Do you have a serial console? 


>    Note that at this point I am only trying to do secondary passthrough
>    though I would ideally like to get to the point of doing primary
>    passthrough.  Adding the line gfx_passthru=1 at any point in all this to
>    the machine config however just prevents the VM from booting entirely;
>    when I VNC in all I get is a qemu prompt and I never get any ouput to the
>    real display.
> 

AMD/ATI primary passthru requires extra patches to Xen qemu-dm,
those are not included out-of-the-box yet.

>    Any suggestions as to how to get this to work would be greatly appreciated
>    as I've hit a bit of a brick wall.  I should also say that I have managed
>    to get secondary passthrough working using Debian Wheezy and the
>    repository version of xen 4.1.  In that case though Dom0 didn't boot
>    reliably.
> 

-- Pasi


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