From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mats Petersson Subject: Re: VGA passthrough and AMD drivers Date: Fri, 7 Dec 2012 15:00:19 +0000 Message-ID: <50C20483.4020200@citrix.com> References: <36774CA35642C143BCDE93BA0C68DC5702C539CC@dulac> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; Format="flowed" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <36774CA35642C143BCDE93BA0C68DC5702C539CC@dulac> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 07/12/12 14:12, Aur=E9lien MILLIAT wrote: > > 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 =91advanced features=92: quad buffer and active = > stereoscopy, synchronization =85 > > The results, for all FirePro drivers (of this year); I can=92t get the = > quad buffer/active stereoscopy feature. > > But they work on a native installation. > Can you describe the setup a little more? How many graphic cards per guest? How many guests? On how many hosts? > > 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]). -- Mats > > Thanks, > > Aurelien >