ASUS M5A99X Evo
Sapphire Radeon HD4550 (dom0)
Sapphire Radeon HD6870 (domU)
From the XEN wiki:
I think copying the graphic bios is only need if you want to replace the emulated card. I only attach my graphic card like a normal pci device. I installed the OS and the gaphic driver normally over VNC. After the reboot the catalyst drives takes care of disabling the incompatible graphic card, the emulated one and switches the video output to the passthrough device. It should work with an appropriate xorg.conf too.Qemu-dm emulator used in the Xen HVM guest needs to disable the internal (emulated) graphics adapter, copy and map the real graphics adapter VGA BIOS to the virtual machine memory, emulate and execute it there to reset and initialize the graphics card properly, map and passthru the VGA adapter real memory to the HVM guest, passthru all the legacy IO-port and legacy memory ranges from the HVM guest to the real graphics adapter etc.
At first i used plain Xen 4.1.2 without any patches. But due an avx bug in glibc i had to apply 3 patches(24341, 24344, 24345) from unstable and add "xsave=1" to the hypervisior boot options. I think the patches are only needed on AVX capable cpus.
For completeness my configs:
xen-domu: http://pastie.org/3673572 mostly like the default config
Unfortunately, the powermanagement is not working with an AMD Bulldozer. But this will hopefully come in Linux 3.4 :-)