Re: [Xen-users] ATI VGA Passthrough / Xen 4.2 / Linux 3.8.10

[Casey DeLorme <cdelorme@xxxxxxxxx>]

Hello Gordan, Casey,

I hope you've had a good weekend. ÂI got back to my project this
morning; I decided to shove one of my 5850's into my board to see if I
could get it to work...

I've had this Windows DomU running, with GPLPV drivers, for a few
hours now. ÂPerformance is excellent. ÂI'm using the 5850
passed-through as a PCIe device. ÂOne of my 6990s is also plugged in,
and it's being used by Dom0. ÂComically, I've got the better monitor
plugged into my Dom0's card because this 5850 lacks mini displayport
:D

I also can't get gfx_passthru=1 to work. ÂNothing happens other than
an SDL window claiming to be a Serial console showing up on my Dom0's
screen. ÂI even have the 5850 set up as my BIOS's primary video card.
Oh well :)

For primary passthrough (which is what the gfx_passthru=1 flag is supposed to set), you need to apply AMD patches to the Xen source code manually and rebuild. ÂI have not yet tried this myself and simply make do with secondary passthrough.

Gordan, I'm going to poke through your other email later and see if I
can present some information to help you line up any of your
suspicions. ÂGiven the way things have gone for me---and I've
basically duplicated as much of your and Casey's setups as humanly
possible here---I've got to believe the problem here is ACS, or
something related to it. ÂI can even reboot this VM and the card just
keeps on working.

Have you rebooted and then tried a 3D Application as well? ÂRebooting works fine for me with the windows interface since that requires very little in the way of graphics power. ÂHowever if I do not eject the card after a reboot prior to starting up a 3D application, such as a game, it will run either very slowly or the software crashes. ÂIf you are not experiencing that, then you have somehow worked around the degraded passthrough performance.

On another note, should we retire this thread soon? ÂIt's getting a
bit long and I don't want to discourage any future googlers, nor get
too off topic :P

I think it is a good thing that we have a long email chain. I only wish I had run across a discussion like this when I was setting up my system.

~Casey

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