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Re: [Xen-users] VGA passthrough success (with doubts)

On Mon, Feb 14, 2011 at 08:22:09PM -0800, Leonardo Prosperi wrote:
>    Hi,
>    I have got VGA passthrough to work in my computer with Windows7 HVM guest.


>    Motherboard: ASUS Crosshair IV Formula (890fx chipset)
>    Video card: HIS Radeon HD 6850
>    Xen: 4.0.2-pre2 from xen-4.0-testing.hg
>    Kernel: pvops dom0 kernel 2.6.32 from Jeremy's xen.git
>    In order to compile Xen 4.0 in Ubuntu 10.10 I changed the default python
>    directory in Makefile as describe in the guide.
>    I downloaded the bios from my videocard and I patched Xen to load the
>    vgabios. ( I don't know if this is necessary)

Did you try without?

>    I compiled the kernel with EXT4 support and the driver for my network
>    card.
>    In the Grub configuration file I added:
>    iommu=1
>    xen-pciback.hide=(05:00.0)
>    text
>    05:00.0 is a SATA controller, it is not the videocard.

So I take it you're passing SATA controller to Windows aswell?

>    If I hide the videocard with pciback, I cannot see the console and I have
>    to use SSH.


>    I wrote a script that disconnects the videocard and the USB controller
>    (where mouse and keyboard are connected) from dom0, and then start the HVM
>    guest.
>    I pass the 3 available pci controllers to the HVM guest and the system
>    boots Windows 7 without problems.


>    I don't see the BIOS messages and the Windows 7 loading screen, but I see
>    only the login screen (there is a patch for this, but I will test it
>    later)
>    I can see the Windows 7 loading screen, if I have use SSH+VNC from another
>    computer.
>    The HVM guest has full 3D acceleration and it uses Catalyst 11.1 drivers.


>    I hope this info will help someone else.

It should!

>    It is working but I have some questions for the experts:
>    I don't use: gfx_passthru=1 , if I enable it, VGA passthrough doesn't work
>    and VNC will connect to the QEMU console.
>    Why does it work without gfx_passthru=1?

That's interesting. Any ideas? 

Any errors in the logs? "xm log" and also /var/log/xen/*

>    I used GPU-Z to detect the video card in Windows 7 HVM, and it reported
>    that it is using boch vgabios.
>    Is there a way to know if the real BIOS is loaded?

Hmm.. weird. Oh, it's probably the primary qemu vga adapter,
I bet you have two vga controllers in the VM because you don't have 
gfx_passthru=1 enabled?

>    I cannot pass the keyboard as USB device, I had to pass the USB
>    controller.
>    How can I pass the keyboard as usb device?

There are some prelimiary patches for this, but no final 'clean' solution..
Some XCI guys were working on this earlier, but I don't know the current 

>    Is there a way to pass the video card back to dom0?

Not sure.

-- Pasi

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