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Re: [Xen-users] [Xen-devel] VGA passthough still not working

Most people run Xen for headless virtual machines, and VGA passthrough requires VT-d support in both the CPU and motherboard. VGA passthrough is also somewhat dependent on the card you're using it with, so it's a hard thing to test. If you want it to get more love, then you're the best situated person to do it :)

However, on the topic of Sandi's issue:
If your monitor goes black, that's a GOOD sign - it's indicative that the dom0 is relinquishing control of the graphics card, so at least that's working. In my experience using graphics passthrough, this problem is related to your card not being fully supported; essentially, Xen can't pass your card through to the VM during boot. If you leave the `gfx_passthru` option *disabled*, you'll have the emulated cirrus card (by default) and it will at least boot successfully. Here's some step by step suggestions/instructions:

  • disable gfx_passthru in config (delete the option or set it to 0)
  • enable VNC, listening on all interfaces
  • start the VM - your screen should still go black
  • From another machine (what with your screen being black), connect in via VNC and fire up the device manager in XP. I don't have any XP boxes left, but in Windows 7, you should see a device in an error state under 'Display adapters'.
  • Check its PCI slot under 'details' - "Location Paths" should help. Compare that to `xm pci-list [domain name]` to see if it matches up with the graphics card.
  • Install the driver for that device
  • Reboot. You won't see the BIOS on the monitor, but it should use it once Windows takes over.

If something in there doesn't work, hopefully I can help you debug - I went through a lot of this a while back.

On Fri, Jan 20, 2012 at 2:24 PM, chris <tknchris@xxxxxxxxx> wrote:
I'm really surprised this doesnt get more attention. For as long as I've been on this list, this feature has been mentioned so many times I would think that getting this working would be a huge feature that would make the product even better. I have only seen the occasional success with experimental patches etc, despite this being talked about for years.

On Fri, Jan 20, 2012 at 1:53 PM, Likarpenkov Alexander <al@xxxxxxxxxxxxxxx> wrote:
Please make a manual
or let's together make


SR> Pasi,

SR> I have that enabled in my BIOS, VT-d for the chipset and VT-x for the

SR> Have you managed to pass your gpu through to the domU?

SR> Regards

SR> Sandi
SR> On Jan 20, 2012 4:47 PM, "Pasi KÃrkkÃinen" <pasik@xxxxxx> wrote:

??>> On Fri, Jan 20, 2012 at 02:05:43PM +0100, Sandi Romih wrote:
??>>> Â ÂHello,
??>>> Â ÂI have spent a lot of time trying to get gfx passthru working on
??>>> my
??>> system
??>>> Â Âwithout success.
??>>> Â ÂI looked onto my hardware capabilities again to make sure that it
??>>> does  support VT-d and I am not too sure that it does fully.  My
??>>> hardware is as follows: Â - Supermicro X8DTH-6F motherboard (5520 chipset
??>>> which supports VT-d) Â - single Xeon X5650 CPU (which is listed as
??>>> supporting VT-x, no
??>> mention of
??>>> Â ÂVT-d at [1]ark.intel.com)
??>>> Â ÂNow, according to the [2]VTdHowTo, the motherboard BIOS, chipset
??>>> AND
??>> CPU
??>>> Â Âneed to support VT-d.
??>>> Â ÂWhat confuses me is, why is the 55x0 chipset listed there if none
??>>> of
??>> the
??>>> Â ÂCPU's supported, that I know of, dont have the VT-d feature
??>>> option,
??>> only
??>>> Â ÂVT-x.

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