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Thanks for the detailed reply, Gordon. Very helpful!

Can someone tell me which Xen release implements reinitializing passed through devices to fix the AMD driver bug when rebooting the domU?

I believe I read somewhere that perhaps a new AMD graphics card driver might solve the issue. Does anybody know about that?

It's quite strange that on one side AMD supports VGA passthrough (a lot more than Nvidia does), but on the other side they haven't fixed their Windows driver to properly reset the card (at least that is how I understand it).

This domU reboot issue with xl has been around for some time and I was hoping that some fix has trickled into a recent Xen release or AMD driver release.

On Tuesday, March 11, 2014 9:13 PM, Gordan Bobic <gordan@xxxxxxxxxx> wrote:

Reboot issues are an ATI-only problem. Nvidia cards don't suffer from it because the driver in domU does a much better job than ATI's.

This is the main reason why there has recently been a lot of noise about modifying GeForce cards into Quadros for virtualized gaming. I run a pair of modified 780Ti cards (faux Quadro K6000). Up to and including GTX480 you can soft mod it by editing half a byte in the BIOS straps.

There were patches posted a while back that implement re-initializing passed through devices via a PCI bus reset but I don't know what release those will land in off the top of my head.

"H. Sieger" <powerhouse.linux@xxxxxxxxx> wrote:

Hello,

Hope you can help. A while ago users noted performance degradation or dom0 stability issues when shuting down a HVM guest that uses VGA passthrough (e.g. Windows 7), and booting up the guest again. A workaround was to eject the graphics card within Windows, before shutting down the guest. This process is described here: http://blog.ktz.me/?p=219.

I tried to follow those instructions, but my Windows 7 guest wouldn't boot again after installing the startup and shutdown scripts. Manual eject/insert of the graphics card running the "logon" script worked fine, however (i.e. not a problem with incorrect PCI device ID).

Following this failure and after removing the startup/shutdown scripts, I booted and shutdown the Windows guest repeatedly, each time running a Unigine benchmark to test graphics performance. Surprise: everything works just fine.

Now the question: I'm using a Nvidia Quadro 2000 card and I was wondering if this guest reboot issue was only related to AMD graphics cards?

Or has this bug been fixed in Xen 4.3? I like to know.

Thanks in advance.

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Re: [Xen-users] VGA passthrough with Xen 4.3 and xl toolstack - performance degradation resolved?