Re: vga passthrough // questions about pci passthrough

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2012-07-18 07:45, Martin Wolf wrote:
> Hello,
> 
> i was able to passthrough an AMD 7870 videocard to my win7 guest machine.

Would you add it to http://www.linux-kvm.org/page/VGA_device_assignment?

> my host is ubuntu 12.04 with stock kernel.
> my system contains:
> dq67sw q67 mainboard
> i5-2400s cpu
> sapphire 7870 amd videocard
> xonar d2x (problems to passthrough)
> 
> for full functionality i just needed two options
> 
> - kernel : iommu=on
> - kvm module: ignore_msrs=1
> (if i would not set it the guest os would crash with a bluescreen)

Can you report (=> kernel log) which MSRs are unknown to KVM?

> 
> the unigine benchmark ran flawlessly
> also the benchmark included in windows gave my videocard
> similar values (7.7) comparable with my native win7 (7.9)
> 
> 
> now to my questions...
> 1.     is it possible to reset the videocard properly to be able to
>     reboot the vm?

Which versions of kernel and qemu-kvm are involved via your distro? Can
you retry with latest Linux (3.5-rcX) / lastest qemu-kvm? Maybe
something got fixed meanwhile.

In general, there are many adapters that require special procedures to
perform resets. This one may fall into that category as well.

> 
> 2.    the xonar d2x is a very nice audio card, it would be very handy
>     to be able to use it in the vm. in my oppinion the card is a
>     d2 with a pci-e to pci bridge.
>     i tried to passthrough the card alone and with the pci-bridge
>     that was shown though lspci, but i had no success.
>     maybe you guys here have an idea on that topic?

Any further details about the error? Does the adapter work with a Linux
guest or provide more information that way?

Jan


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