Re: [Xen-users] Xen 4.7.0 graphics pass through problems (Win10, AMD Radeon)

[Peter Milesson <miles@xxxxxxxx>]

On 2016-09-14 15:30, George Dunlap wrote:
> On 14/09/16 14:23, Andrew Cooper wrote:
> > On 14/09/16 13:50, Jan Beulich wrote:
> > > > > > On 14.09.16 at 13:34, <george.dunlap@xxxxxxxxxx> wrote:
> > > > >   On 2016-09-09 09:51, Peter Milesson wrote:
> > > > [snip]
> > > > > > I've been using Xen for 3 years, starting out with 4.2, and I've been
> > > > > > upgrading regularly, and installed 4.7.0 today.
> > > > > >
> > > > > > I'm using Windows 10, 64-bit with PCI pass through in a VM with
> > > > > > PV-drivers, using a AMD Radeon HD6450 card (AMD graphics cards don't seem to
> > > > > > need graphics pass through)
> > > > > >
> > > > > > Previously (up till Xen 4.6.3), the graphics output has displayed some
> > > > > > shorter lines, a bit like thin coarse snow, when watching videos. The
> > > > > > distortions stayed within the movie, and was tolerable.
> > > > > >
> > > > > > After upgrade to Xen 4.7.0, the video performance is seriously ugly. Just
> > > > > > for example, I open cnn.com and move the mouse pointer up and down over the
> > > > > > photos, which creates a bunch of flickering lines over the display. The same
> > > > > > with moving content in Youtube for example. Or opening a Cygwin terminal
> > > > > > window and scrolling through a file. Terrible.
> > > > > >
> > > > > > Nothing else has changed, only the Xen version.
> > > > [snip]
> > > >
> > > > On Fri, Sep 9, 2016 at 10:35 AM, Peter Milesson <miles@xxxxxxxx> wrote:
> > > > > Hi again,
> > > > >
> > > > > I've been playing around a bit more.
> > > > >
> > > > > It seems one of the problems is that I passed a couple of PCI-devices (USB
> > > > > controllers) to the VM, beside the graphics card.
> > > > >
> > > > > When I pass the USB-devices individually in the VM configuration file
> > > > > (usbdevice=['tablet','host:1.4','host:1:9','host:x.y']), the display
> > > > > problems seem to be more or less gone.
> > > > Jan / Andy,
> > > >
> > > > Can you think of anything that's changed between 4.6 and 4.7 that
> > > > would cause the performance problems he's describing when both a video
> > > > card and a usb controller are passed through, but not when only the
> > > > video card is passed through?
> > > Not really, no. Peter - are there any indications of problems in
> > > one or more of the logs (Xen, xl, qemu)? Did you try running a
> > > debug build of all Xen components?
> > Furthermore, does "Nothing else has changed, only the Xen version." mean
> > switching your distro packages between two versions of xen, or literally
> > only switching the hypervisor itself.
> I assume he's using "Xen" to mean the whole Xen system -- hypervisor +
> tools + qemu.
>
> > A substantial quantity of the complexity here is in qemu, rather than Xen.
> Rather than the hypervisor, you mean.
>
> Another thing worth asking, Peter: Have you tried running with
> qemu-traditional (by adding the line below to your config file) rather
> than qemu-upstream, to see if that makes a difference?
>
> device_model_version="qemu-xen-traditional"
>
> qemu-traditional almost ever changes, so if it worked better, then that
> would point the finger at changes in qemu (at which point we would have
> to bring in a different set of people to help diagnose it).
>
>   -George
Hi George,

I have always been using the default. I never had the need to set a 
specific device model. So it's qemu-upstream in my case.
Best regards,

Peter



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