I have done a secondary GPU passthrough to a Linux domU, but I don't know how to output Xorg from the secondary GPU.
The dom0 is using an Intel integrated graphics card. I am passing through an AMD 6450 to domU, as it there were two mentions of it here:
Short list of what I did:
- Enabled VT-d in motherboard BIOS
intel_iommu=onto dom0 GRUB
- Blacklisted modules of GPU and it's audio subsystem
xl pci-assignable-add _______for both GPU and it's audio subsystem
- Added the two PCI IDs to the Xen configuration file:
pci = [ '_____', '_____' ]
- Booted and installed Linux in the domU
When I boot, after the above steps, I get one error message:
libxl: error: libxl_pci.c:1151:libxl__device_pci_reset: The kernel doesn't support reset from sysfs for PCI device 0000:01.00.0
Despite the above error, when I run
lspci -nnk on the domU, it shows the GPU and audio sub-device, including these lines:
Kernel driver in use: radeon
Kernel driver in use: snd_hda_intel
Also, of course, a line for the primary domU virtual GPU:
Kernel driver in use: cirrus
Then, if I connect a VGA or DVI cable from the passed through GPU to the monitor, the monitor stays on (green power button) with a dark grey screen. Whereas usually, when the monitor detects no input, it just goes straight to standby (orange power button). So there is some kind of GPU output.
startx and run
xrandr through VNC, there doesn't seem to be any sign of the physical monitor, it seems there is only the virtualized
If I add
gfx_passthru=1 to the configuration file, it always fails at boot. The first error message that appears when I add
libxl: error: libxl_dm.c:1302:libxl__build_device_model_args_new: unable to detect required gfx_passthru_kind
Before I ever used virtualisation, to switch output from primary/secondary graphics card to the other, I would usually just change the settings in the BIOS, and Linux would follow. So Xorg + domU is very different territory for me.
Does anyone know how I can output Xorg through the secondary GPU in the domU, after this point ? Various GPU passthrough guides online only cover Windows.
After StrongBad's response, I have moved from an Arch domU to a Debian 8.8 from the Debian wiki domU, as
fglrx is not in the official Arch repos anymore.
However, unlike the Arch domU, the Debian domU has no mysterious dark grey monitor output with always-on green power button, when the passed through GPU is connected to the monitor.
Nonetheless, I did the following:
sudo aticonfig --initial
- Added the four lines to
/etc/xorg.conffrom the Debian wiki
However, when I run
startx from a VNC TTY, it just crashes. The first error message in
(EE) fglrx(0): Failed to open CMMQS connection