I am trying to use the open source Radeon driver on Linux with a passed through secondary VGA device. I am running Xen 4.4.0 on Arch Linux (kernel 3.14.6). I have Gigabyte X79-UP4 motherboard and two Gigabyte GV-R545-1GI (Radeon 5450 chipset) video cards. I can pass either (the primary one that the Dom0 BIOS comes up on or the secondary one) VGA device to a Windows XP DomU (qemu-xen-traditional) as a secondary VGA device in conjunction with virtual Cirrus VGA device. The passed device works perfectly and is stable across DomU reboots. I can also pass either VGA device to an Arch Linux (kernel 3.14.6) DomU (qemu-xen-traditional) as a secondary device and the passed device works perfectly with the Catalyst closed source drivers, but doesn't work at all with the open source Radeon driver. I k now I should just be happy that I can pass through VGA devices at all, but I keep hoping I will be able to get it to work with the open source drivers. $ dmesg | grep -E '(radeon|drm)' [ 0.436833] [drm] Initialized drm 1.1.0 20060810 [ 0.441222] [drm] radeon kernel modesetting enabled. [ 0.442083] [drm] initializing kernel modesetting (CEDAR 0x1002:0x68F9 0x1458:0x254A). [ 0.442096] [drm] register mmio base: 0xF3000000 [ 0.442097] [drm] register mmio size: 131072 [ 0.442127] radeon 0000:00:05.0: Expecting atombios for evergreen GPU [ 0.442161] radeon 0000:00:05.0: Fatal error during GPU init [ 0.442187] [drm] radeon: finishing device. [ 0.449566] radeon: probe of 0000:00:05.0 failed with error -22 The errors look essentially the same as https://bugzilla.kernel.org/show_bug.cgi?id=57831, where the claim is that the VBIOS is not being passed correctly. How can I determine if my issue is that Xen/Qemu is not passing the the correct VBIOS? If this is in fact the case, is there a way to fix this without having to use the closed source drivers or enter the hell that is primary VGA pass trough? Is it worth filing a bug report some place? The driver developers closed the bug as invalid even though the closed source driver handles the issue gracefully. This message and any attachment are intended solely for the addressee and may contain confidential information. If you have received this message in error, please send it back to me, and immediately delete it. Please do not use, copy or disclose the information contained in this message or in any attachment. Any views or opinions expressed by the author of this email do not necessarily reflect the views of the University of Nottingham. This message has been checked for viruses but the contents of an attachment may still contain software viruses which could damage your computer system, you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation.