Having updated from 4.1 to 4.4 I am now using the xl toolstack, and it seems that there is a bug dealing with VGA passthrough. I have a Windows guest and can get the card to show up, however it throws the error "If you want to use this device, you will need to disable one of the other devices on this system." qemu's log shows "pt_pci_read_config: [00:05:0] Error: Failed to read register with invalid access size alignment. [Offset:0eh][Length:4]" There seem to be plenty of instances of this around the internet, however as far as I have found, there is no solution. -- View this message in context: http://xen.1045712.n5.nabble.com/VGA-Passthrough-in-Xen-4-4-tp5722323.html Sent from the Xen - User mailing list archive at Nabble.com.