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

[Peter Milesson <miles@xxxxxxxx>]

Hi folks,

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.

The current situation is far from acceptable, and my question is, if 
somebody else has got the same experiences, and possibly if there's a 
solution.
If somebody has got a solution here, I'd be very grateful.

Hardware and OS details below.

Best regards,

Peter

*Hardware*
CPU: AMD FX-6100 (6-core)
Chipset: AMD 970A (has got a working IOMMU)
RAM: 16GB DDR3-1600MHz
Video: AMD Radeon HD6450

*OS*
Linux Slackware 14.2 (latest)
Kernel: 4.4.19 long term stable

*Xen*
Version: 4.7.0 (configure same as 4.6.3 and previous versions)
 ./configure --prefix=/usr --localstatedir=/var --sysconfdir=/etc 
--libdir=/usr/lib64 --with-xenstored=oxenstored 
--disable-qemu-traditional --disable-rombios --disable-stubdom
Xen dom0 boot entry (grub2):
menuentry "Xen 4.7.0 / Slackware 14.2 (kernel 4.4.19-dom0)" {
       set root=(hd0,1)
       multiboot /boot/xen-4.7.0.gz iommu=1 dom0_mem=2048M 
dom0_max_vcpus=2 dom0_vcpus_pin console=vga cpufreq=xen:performance noreboot
       module /boot/vmlinuz-4.4.19-dom0 console=vga earlyprintk=xen 
root=/dev/sda1 ro clocksource=xen xencons=off
}

*Guest OS*
Windows 10 Pro 64-bit (2VCPUs)
Latest PV Drivers (8.2 series)
Graphics driver: Latest WHQL driver 15.201.1151.1008


_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxx
https://lists.xen.org/xen-users