[Qemu-devel] Graphics Device Passthrough

[Qemu-devel] Graphics Device Passthrough

[Adhyas Avasthi]

[-- Attachment #1: Type: text/plain, Size: 749 bytes --]

Hello

(newbie hacker to qemu community, so please excuse novice ignorances)



I wish to pass-through a graphics controller to my Windows 7 VM running on
qemu-kvm. I would like it to be PCI-Express (if that works, that is). Are
there any recommended devices that I should purchase for this experiment?

I would like the device to also be accessible from my Fedora Core 10 host.



Basically, I wish to have the device pass-through when I run the VM, I then
wish to eject the device out of the VM (hot-remove), and then give it back
to Fedora Core 10 to use. This is how my experiment is defined. I am looking
for suggestions on graphics controllers I should think of purchasing for
this experiment. Any help would be appreciated.



Thanks,
Adhyas

[-- Attachment #2: Type: text/html, Size: 3099 bytes --]

Re: [Qemu-devel] Graphics Device Passthrough

[Blue Swirl]

On Sat, May 22, 2010 at 4:49 PM, Adhyas Avasthi <adhyas@gmail.com> wrote:
> Hello
>
> (newbie hacker to qemu community, so please excuse novice ignorances)
>
>
>
> I wish to pass-through a graphics controller to my Windows 7 VM running on
> qemu-kvm. I would like it to be PCI-Express (if that works, that is). Are
> there any recommended devices that I should purchase for this experiment?
>
> I would like the device to also be accessible from my Fedora Core 10 host.
>
>
>
> Basically, I wish to have the device pass-through when I run the VM, I then
> wish to eject the device out of the VM (hot-remove), and then give it back
> to Fedora Core 10 to use. This is how my experiment is defined. I am looking
> for suggestions on graphics controllers I should think of purchasing for
> this experiment. Any help would be appreciated.

I don't think PCI pass-through is implemented yet. If there are no
interrupts, it could be made to work.

QEMU only emulates basic VGA, Cirrus CLGD 54xx, VMWare and XenFB
devices. Only VGA or Cirrus are physically available and these should
not be expensive if they can be found.

For accelerated 2D or 3D, new emulated devices would be needed to be
added to QEMU, so this would make your experiment much bigger. It
could be interesting to emulate some very recent devices, like NVidia
or Radeon cards with a GPU. It's obvious that emulation with only host
CPU support would be very slow but in your pass-through setting that
would not matter. The reverse, using host GPU devices to emulate for
example x86, could also be useful, though the processing power of a
single unit in a GPU is not that much.

If OGP is still alive, that may be another alternative, free emulator
for a "graphics cards with Free-licensed specifications and Free
Software drivers".

The general trend is to virtualize the display, see for example Spice efforts.

RE: [Qemu-devel] Graphics Device Passthrough

[adhyas.avasthi]

In the options for qemu, I did see an option that allowed me to define a host bus:dev:fn number to be accessible to the guest. This was not one of the USB options I believe. So I assumed some kind of pass-through support is present.

For a PCI pass-through, we probably would not need to emulate the device completely (or else what is the need of pass-through). We can emulate just a few of the capabilities, and the command/INT registers that are needed to be emulated. Even VMware pass-throughs the rest AFAIK. I didn’t realize qemu-kvm did not have this support yet.

PS: I have read papers that read about similar experiments people have carried on qemu. Didn't realize no code was checked back in the source tree. Thanks for letting me know.

Thanks,
Adhyas

-----Original Message-----
From: qemu-devel-bounces+adhyas.avasthi=nokia.com@nongnu.org [mailto:qemu-devel-bounces+adhyas.avasthi=nokia.com@nongnu.org] On Behalf Of ext Blue Swirl
Sent: Saturday, May 22, 2010 12:58 PM
To: Adhyas Avasthi
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Graphics Device Passthrough

On Sat, May 22, 2010 at 4:49 PM, Adhyas Avasthi <adhyas@gmail.com> wrote:
> Hello
>
> (newbie hacker to qemu community, so please excuse novice ignorances)
>
>
>
> I wish to pass-through a graphics controller to my Windows 7 VM running on
> qemu-kvm. I would like it to be PCI-Express (if that works, that is). Are
> there any recommended devices that I should purchase for this experiment?
>
> I would like the device to also be accessible from my Fedora Core 10 host.
>
>
>
> Basically, I wish to have the device pass-through when I run the VM, I then
> wish to eject the device out of the VM (hot-remove), and then give it back
> to Fedora Core 10 to use. This is how my experiment is defined. I am looking
> for suggestions on graphics controllers I should think of purchasing for
> this experiment. Any help would be appreciated.

I don't think PCI pass-through is implemented yet. If there are no
interrupts, it could be made to work.

QEMU only emulates basic VGA, Cirrus CLGD 54xx, VMWare and XenFB
devices. Only VGA or Cirrus are physically available and these should
not be expensive if they can be found.

For accelerated 2D or 3D, new emulated devices would be needed to be
added to QEMU, so this would make your experiment much bigger. It
could be interesting to emulate some very recent devices, like NVidia
or Radeon cards with a GPU. It's obvious that emulation with only host
CPU support would be very slow but in your pass-through setting that
would not matter. The reverse, using host GPU devices to emulate for
example x86, could also be useful, though the processing power of a
single unit in a GPU is not that much.

If OGP is still alive, that may be another alternative, free emulator
for a "graphics cards with Free-licensed specifications and Free
Software drivers".

The general trend is to virtualize the display, see for example Spice efforts.

RE: [Qemu-devel] Graphics Device Passthrough

[Stefano Stabellini]

[-- Attachment #1: Type: text/plain, Size: 1067 bytes --]

On Sun, 23 May 2010, adhyas.avasthi@nokia.com wrote:
> In the options for qemu, I did see an option that allowed me to define a host bus:dev:fn number to be accessible to the guest. This was not one of the USB options I believe. So I assumed some kind of pass-through support is present.
> 
> For a PCI pass-through, we probably would not need to emulate the device completely (or else what is the need of pass-through). We can emulate just a few of the capabilities, and the command/INT registers that are needed to be emulated. Even VMware pass-throughs the rest AFAIK. I didn’t realize qemu-kvm did not have this support yet.
> 
> PS: I have read papers that read about similar experiments people have carried on qemu. Didn't realize no code was checked back in the source tree. Thanks for letting me know.
> 

Xen supports graphic device passthrought since version 4.0, if you are
interested the wiki page is here:

http://wiki.xensource.com/xenwiki/XenVGAPassthrough

depending on the device you want to passthrough it might be easy or very
difficult though...