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Re: [Xen-users] VGA/PCI Passthrough of Secondary Graphics Adapter

On 04/28/2013 07:11 AM, Casey DeLorme wrote:

The lack of FLR, to my understanding, prevents the virtual machine from
resetting the card state, leaving it initialized when switching or
rebooting your DomU.  As a result the card is activated multiple times,
creating various issues with a range of problems.

You see, I'm not actually convinced FLR is such a vitally important feature. All you are really doing with FLR is pushing the re-initialization responsibility onto the BIOS of the PCI device. Without it, the driver has to do it. What is it that the driver cannot do to reset the device? Think low-level - all you are really doing is putting values into the registers of the GPU.

During my tests, I broke down the steps logically to resolve the issues
I had installing and updating drivers.  In general, anytime I update or
install AMD drivers I would reboot the entire physical machine to ensure
the graphics card state was proper.

Interestingly, the one thing that various people have been saying about ATI cards is that they get slower and slower on every guest reboot, unless you reboot the host. I haven't seen any evidence of this on my 6450. The fps I get in the likes of OCCT and Furmark are the same after the guest has been rebooted a few times. The problem I have is that an application entering full-screen mode causes a crash.

 From my experiences this required a freshly installed Windows system,
if you are working on a system you already attempted driver installation
on and it failed (BSoD's or otherwise) uninstalling the failed drivers
and trying again loops back to the same failures for mostly unknown
reasons.  Presumable it has to do with the use of the .NET framework for
installation, and leaving bits of data behind on failure, but I never
confirmed the exact details.

I don't know if that helped in any way, but I uninstalled anything remotely .NET-ish, including the client profile.

For me, once the drivers are properly installed, rebooting the system
still leaves the card in a pre-initialized state, which to avoid
performance degradation I would manually reset the card using eject
media from the lower right icon.  This is not a perfect solution, and I
do not rely on it when performing driver installation or updates.

Where is this "eject" for a PCI device? What distro are you actually running?


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