Go!

After being able to do Intel HD 4000 VGA passthrough I decided I wanted to try PCI passthrough of a dedicated graphics card. My idea was to buy a AMD HD 7850  but I ended up buying a second hand AMD HD 5450 passively cooled for 15€ just be sure that PCI passthrough of secondary GPU works before making a much bigger purchase such as the HD 7850.

Well it worked.

Passing the AMD HD 5450 to a Windows 8 domU was a bit trickier than passing the primary Intel VGA but still achievable though I found the driver installation awkward.

Some notes:

• The integrated Intel i7-3770 HD 4000 GPU needed to be set as the Primary Display Adapter in the BIOS thus the AMD HD 5450 was setup as the Secondary Display Adapter.
• Wheezy domU with stock Linux kernel and Xen 4.1.3 were used alongside the xm toolstack.
• The domU was installed over VNC.
• The HDMI audio function of the graphics card also needs to be passed.
• Installing AMD Catalyst froze the VM and required a reboot of the dom0 to restart the Windows 8 domU properly. I worked around this by installing only the drivers with Catalyst Control Center.
• Windows 8 assigned drivers to the AMD HD 5450 that were faster in Windows Performance Score, Counter Strike Source Video Stress and Unigine than AMD 12.8 drivers (!)
  
• AMD HD 5450 performance is crappy compared to Intel HD 4000 however it's more than fine for Windows 8 non-gaming tasks.
• AMD HD 5450 Team Fortress 2 gameplay was crappy with ~30 FPS.
• I wasn't able to successfully passthrough my 2nd Intel NIC as the VM refused to start and spat out errors.
• I'm too hooked on FT2 having scored 50h since early September which is totally sucked my free time...

Next steps? Well...

• 2 concurrent Windows 8 domUs one running the integrated HD 4000 and the other the AMD HD 5450.
• Clean up the benchmarks I've run on bare metal, HD 4000 and AMD HD 5450 domU.
• Clean up my notes and publish as HowTo on linux-bsd-sharing.blogspot.com.
• Setup Linux domUs with VGA passthrough.

Overall I'm pleased to being able to passthrough AMD's cards but the little sucker is too slow :(