Re: [Xen-users] VGA/PCI Passthrough of Secondary Graphics Adapter

[Gordan Bobic <gordan@xxxxxxxxxx>]

On 04/30/2013 07:27 PM, Ole Johan Væringstad wrote:
> I too got the atikmpag.sys BSOD initially, I got around it by installing
> the 12.104 drivers. It also took me a while to realize I had a "working"
> solution:
>
> I would install the drivers, then reboot the dom0, start the domU,
> connect vnc, and then windows would hang on "Starting Windows". Turns
> out windows completes the login (I set up auto-login) on the output of
> the card I passed through. In device manager the emulated VGA adapter
> shows an error, while the ATI card is fine. If I reboot domU, the
> emulated VGA is fine, while the ATI card shows an error. For a while I
> thought I had to do a dom0 reboot, which fixes it, but ejecting the card
> also works (although I will have to find a way to shut down the domU "in
> the dark" which is cleaner than xl destroy).
I haven't found any correlation between dom0 reboots and domU working. 2 
days ago, I was rebooting domU multiple times without rebooting dom0. 
Yesterday it didn't matter how many times I rebooted either, domU just 
wouldn't start up and BSOD-ed every time before the login screen appeared.
> My passthrough card is an Asus HD7970. I initially had an Asus HD7770 as
> my dom0 card, but that caused problems. I have the 7970 in the first
> PCIe slot and the dom0 in the second, but I can set in bios which prints
> POST. I could not get an ATI driver to work in dom0. I tried the open
> source Radeon driver, which needed mesa 9.1+ for acceleration with
> Southern Islands/HD7xxx, which again needed a patched llvm I had to pull
> from the git-repo of what I actually believe is an AMD engineer. Still,
> glxgears gave me 5-7 fps. It might have worked nicely without
> acceleration but I needed that for monitor rotation. Note that you only
> need mesa 9.1+ for SI/HD7xxx. The AMD's official driver gave me an
> amputated xorg.log and ugly segfaults. I pulled out the card and
> installed my old nVidia GTX275, which now works like a charm with the
> binary driver. I will order something like an nVidia GTX650 because my
> 275 only supports 2 monitors and I need 3. I got the HD7770 as a dom0
> card because I thought it would simplify matters, turns out the opposite
> was true. But I do not know if this is related to xen, could be a lot of
> things.
My experience is that ATI cards rarely simplify matters. The moment you 
go off the straight and narrow (single monitor, nothing weird like 
virtualization) things start to fall apart very quickly, especially in 
Windows. FGLRX driver is actually pretty decent in Linux, but it's lack 
of ability to build for dom0 is a major failing, and likely an 
unacceptable one for people on this list.
> I hope this information will be useful to someone beyond myself, because
> I had to spend quite a bit of time to get it to work. Time is money too,
> so there comes a point where buying working solutions becomes cheap. I
> would like to see a database of working hardware combinations. (Atleast
> I would have loved to when I was setting it up)
>
> Setup:
> Gigabyte GA-X79S-UP5 with i7-3820
> Gentoo dom0 at 3.7.10, 3.8.10, will now test 3.9.0
> Xen 4.2.0 from portage, xl toolstack
> nVidia GTX275 as dom0 VGA
> Asus Radeon HD7770 DCU-II as domU Secondary Passthrough
> Windows 7 64bit with PV drivers.
> AMD 12.104 drivers
> xen kernel options:
>    dom0_mem=8192M,max:8192M
>    dom0_max_vpcus=4
>    dom0_vcpus_pin
>    iommu=1
>    xsave=1
> linux kernel options:
>    xen-pciback.permissive
>    xen-pciback.hide=(USBbus and VGA card)
What does xen-pciback.permissive do?

I found that regardless of xen-pciback module options, I have to 
manually detach the devices from dom0 after loading the xen-pciback module.
Gordan


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