I''ve been trying to pass through a GPU to a domU, so far with a lot of trouble but finally a success. PCI passthrough works, I''ve had the usb hubs work successfully. Today I tried to pass through my ATI card to an ubuntu hvm domU with no gfx_passthru and got this: [...] (XEN) memory_map:add: dom14 gfn=f3040 mfn=f7c40 nr=4 (XEN) memory_map:remove: dom14 gfn=f3040 mfn=f7c40 nr=4 (XEN) memory_map:add: dom14 gfn=f3040 mfn=f7c40 nr=4 (XEN) irq.c:270: Dom14 PCI link 0 changed 5 -> 0 (XEN) irq.c:270: Dom14 PCI link 1 changed 10 -> 0 (XEN) irq.c:270: Dom14 PCI link 2 changed 11 -> 0 (XEN) irq.c:270: Dom14 PCI link 3 changed 5 -> 0 (XEN) irq.c:2234: dom14: pirq 51 or emuirq 23 already mapped (XEN) vmsi.c:108:d32767 Unsupported delivery mode 3 (XEN) emulate.c:88:d14 bad mmio size 16 (XEN) io.c:199:d14 MMIO emulation failed @ 0033:7fa98cc628b4: 66 0f 7f 0f 0f 28 56 10 0f 29 (XEN) stdvga.c:147:d14 entering stdvga and caching modes (XEN) stdvga.c:151:d14 leaving stdvga (XEN) emulate.c:88:d14 bad mmio size 16 (XEN) io.c:199:d14 MMIO emulation failed @ 0033:7f28312e98b4: 66 0f 7f 0f 0f 28 56 10 0f 29 (XEN) stdvga.c:147:d14 entering stdvga and caching modes Xen 4.2 unstable on Ubuntu 12.04 with 3.4 kernel, same for the Ubuntu client. Nothing shows on the ATI card (monitor says no signal) and the vnc terminal shows garbage (blue lines). What does this mean? I''ve tried the same setup with gfx_passthru on, making sure to boot using the ATI card (it shows boot messages and such just fine so it''s not obviously broken). There are no obvious errors and the domain appears to run but the ATI card gives no video output. In a third try, with the same setup, I tried passing through the integrated intel GPU. I made an xorg.conf to tell it to use that. The domU sees the card, the X log shows that the intel driver gets loaded and sees the card as well. It successfully detects that there''s a monitor only on VGA1 and even gets the EDID info for it. If I connect the DVI input of the monitor as well, it detects that too. It refuses to show anything though, and the monitor keeps claiming "no signal". The fourth try I did the integrated GPU with gfx_passthru on, and it worked and displays the graphical login screen. First time in a week and a half of tries that I got it to show anything. I''d like to get the ATI card to work though, and I''d prefer having gfx_passthru off so I can keep using the intel GPU as terminal. Does anyone have ideas?