{Guide} Create a Gaming Virtual Machine - Page 2

ok i didn't catch that at all. That kind of explains Plan9's post then. Somehow I was expecting the card to be "shared" but obviously that is nonsense. So is it possible to hot detach / reattach a GPU while either system remains running? Reading about this here it sounds like you can do it for some pci devices, but I would think a GPU is pretty fundamental to remain the same while the machine is running. If not you'd need at least two cards.

I'll see if I can get something going and throw my welfare ATI card in there for some testing. Then if that works i'll consider removing the SLI bridge and running them as separate cards (eventually get a 3rd... and 4th card), and also a KVM switch. I picked up a killawatt meter and this thing only pulls between 400-500W from the wall ... so 4 cards is more feasible than I thought.

alright well i tried this out last night ... and no luck. KVM has long had support for PCI pass through. You simply add a "PCI host device" in the VM definition. I had seen this before but never really knew what it was. very cool. This all works by using existing kernel code and theoretically should be* faster than xen which is more userland code. _If_ it would work ...

It all uses the intel_iommu and DMA remapping parts of the kernel. Either this is just really new and still has some bugs to shake out, or it's a real problem of hardware compatibility. Booting with intel_iommu=on caused the marvell sata controller on my board to cause a kernel panic at boot. Moving the plugs for two of my drives to the other controller and disabling this controller got past that and the system boots. However when I try to startx, the nvidia driver won't load... something about DMA remappings and bits already being set. Either this card / this version of the driver / my config is incorrect. I will try to investigate that a bit further later ..

I think if i could get X to start using these cards, I could easily pass the ATI card I plugged in directly to a VM and it would be perfect. Once I get X started there's a few steps of mapping the busID / IRQ using the pci_stub module ... If that works I'll be dedicating at least one 570 to a windows VM for gaming and ditch this wine crap.

Hi there,

Firstly awesome guide, found it very useful re setup of Xen, there is a few issues I have and am hoping you can help me address them (struggling to find information/guides relevant to this OS/your build):

I am running an i870 (no on chip GPU so figuring this makes a difference tbh)

Trying to start a VM with a hdd image I made (I didnt use partitions as you did due to space issues on my small test drive) I got permissions issues (also got for ISO/CD didn't matter much where I shoved the ISO either

I ran 'setenforce 0' to remove the issue prior to trying passthrough of the GPU etc

When you perform a passthrough of hardware you initially get an error stating PCI-BACK doesn't have/own the hardware, I have found out how to fix this adhoc and that's fine tbh but thought I shoud post the fix for those whom don't know

'sudo lspci' (lists hardware ids) primary gpu should usually list as 01:00.0 my secondary listed as 06:00.0 ans 06:00.1 (sound for secondary card) this was an ATI card, take a note of the ID for the hardware in the above format you will need to unbind this hardware to use it on a VM

'lspci -n' - This gets you the vendor IDs (find the hardware id as per above step in this list and the code listed like xxxx:xxxx is what you seek)

3rdly to unbind the hardware I had to run the following

'echo "xxxx xxxx" > /sys/bus/pci/drivers/pci-stub/new_id
echo "0000:06:00.0" > /sys/bus/pci/devices/0000:06:00.0/driver/unbind
echo "0000:06:00.0" > /sys/bus/pci/drivers/pci-stub/bind'

substitute xxxx xxxx for the values you got from step 2 (xxxx:xxxx format (remove the : and replace with a space as above)

After doing all that I could boot and install an OS (Windows XP and Windows 7 were both setup as testers)

Passed through a dedicated Gigabit NIC and this works fantastically (unbind etc needed as above to make this work however) in either OS

Either OS can see the GPU (tried with an ATI 4350 and a Nvidia 560TI), and it installs the drivers but I get error code 43 (seems common when googling), issue has something to do with patches needing to be installed and this is where I get extremely lost

Any ideas re the patching? Also any tips on how to permanently resolve the other issues (not having to unbind on dom0 boot would be awesome)

BTW I did the unbind etc with the primary card and this caused major issues with the dom0 seems if I ran this via ssh/putty as its the primary GPU it freezes/crashes but can reload virt-manager, though nothing seems to work after this also (any tips here would also be cool)

If I can manage to get this working I can finally wipe and partition my SSD (thus making 2x VMs on it one for me and one for Wife with full GPU passthrough from my pair of 560Ti's


Thanks for all your help in advance and congratulations on an AWESOME guide,
Edited by SoulCleaver - 2/15/12 at 4:35pm

Interesting thread, Booked for sure!

Could you elaborate a little more on this? AFAIK Nvidia cards also have HD audio, otherwise HDMI wouldn't work properly.

Is it the difference in implementation, in that AMD cards have an mobo-style onboard sound card integrated into them whereas Nvidia cards pass a digital audio stream directly to the receiver, that makes the difference here? If that's the case, I guess Xen can't handle digital audio devices?

in my system here the video and audio parts of the card are separate line items in lspci ...



03:00.0 VGA compatible controller: nVidia Corporation Device 1081 (rev a1)
03:00.1 Audio device: nVidia Corporation Device 0e09 (rev a1)
04:00.0 VGA compatible controller: nVidia Corporation Device 1081 (rev a1)
04:00.1 Audio device: nVidia Corporation Device 0e09 (rev a1)


so you would have to just have 2 pci passthrough devices, 1 for the video @ 03:00.0 and one for the audio @ 03:00.1 ... you could also use a virtual sound card, which will fallback to the onboard one, although this isn't true passthrough so it will lag a few ms behind and your audio will be out of sync.

btw since it looks like kvm is going to be about a year or so behind on this, i did go ahead and get all the xen stuff patched in and installed. i've yet to have the time to give it a try.. i will soon
Edited by lloyd mcclendon - 3/4/12 at 10:10am