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Re: [Xen-devel] VGA passthrough and AMD drivers


  • To: "xen-devel@xxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxx>
  • From: Aurélien MILLIAT <Aurelien.MILLIAT@xxxxxxxxxxxxxx>
  • Date: Fri, 7 Dec 2012 16:51:16 +0000
  • Accept-language: fr-FR, en-US
  • Delivery-date: Fri, 07 Dec 2012 16:51:38 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xen.org>
  • Thread-index: Ac3UmuRmhuFUnX+GSrChAek6f4kfgg==
  • Thread-topic: Re: [Xen-devel] VGA passthrough and AMD drivers

>> Hi all,

>> 

>> I have made some tests to find a good driver for FirePro V8800 on

>> windows 7 64bit HVM.

>> 

>> I have been focused on ?advanced features?: quad buffer and active

>> stereoscopy, synchronization ?

>> 

>> The results, for all FirePro drivers (of this year); I can?t get the

>> quad buffer/active stereoscopy feature.

>> 

>> But they work on a native installation.

>> 

>Can you describe the setup a little more?

 

I’ve got 2 HP Z800 workstation with FirePro V8800, one per computer.

It’s a setup used in CAVE system, I try (and its works, minus some issues) to virtualize ‘virtual reality contexts’ that needs full graphics card features.

 

Intel Xeon E5640 CPU with Intel 5520 chipset

cores_per_socket       : 4

threads_per_core       : 2

cpu_mhz                : 2660

total_memory           : 4079

 

>How many graphic cards per guest?

One card per guest.

 

>How many guests? On how many hosts?

One guest per computer.

 

>> 

>> The only driver that allows this feature is a Radeon HD driver

>> (Catalyst 12.10 WHQL).

>> 

>> But this driver becomes unstable when an application using active

>> stereo and synchronization is closed:

>> 

>> -The synchronization between two computers is lost.

>> 

>> -The CCC can crash when the synchronization is made again.

>> 

>> Someone have any clues about this?

>> 

>I don't know exactly how this works on AMD/ATI graphics cards, but I

>have worked with synchronisation on other graphics cards about 7 years

>ago, so I have some idea of how you solve the various problems.

> 

>What I don't quite understand is why it would be different between a

>virtual environment and the bare-metal ("native") install. My immediate

>guess is that there is a timing difference, for one of two reasons:

>1. IOMMU is adding extra delays to the graphics card reading system memory.

>2. Interrupt delays due to hypervisor.

>3. Dom0 or other guest domains "stealing" CPU from the guest.

>I don't think those are easy to work around (as they all have to

>"happen" in a virtual system), but I also don't REALLY understand why

>this should cause problems in the first place, as there isn't any

>guarantee as to the timings of either memory reads, interrupt

>latency/responsiveness or CPU availability in Windows, so the same

>problem would appear in native systems as well, given "the right"

>circumstances.

> 

> 

>What exactly is the crash in CCC?

> 

>(CCC stands for "Catalyst Control Center" - which I think is a Windows

>"service" to handle certain requests from the driver that can't be done

>in kernel mode [or shouldn't be done in the driver in general]).

 

After the application is closed, I launch the Catalyst Control Center, the synchronization state seems to be good. But there is no synchronization.

If I try to apply any modifications of synchronization (synchro server or client), CCC freeze and I need to kill it manually.

I can set the synchronization back after this.

 

I will try next week with others computers.

 

Thanks for the reply,

Aurelien

 

--

Mats

> 

> Thanks,

> 

> Aurelien

> 

 

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