Prevent Radeon driver from attaching to specific PCI devices?
I had had some pci_stub
-related lines in my rc.local
but this was apparently too late in the boot process to help, running after radeon
started fiddling with things.
I fixed things by moving the pci_stub
kernel module stuff to the initramfs
:
lspci -nn | grep Cayman
to find thevendor:device
numbers (at the very end of the line) for the 6950 and its HDMI port:02:00.0 VGA compatible controller [0300]: Advanced Micro Devices [AMD] nee ATI Cayman PRO [Radeon HD 6950] [1002:6719] 02:00.1 Audio device [0403]: Advanced Micro Devices [AMD] nee ATI Cayman/Antilles HDMI Audio [Radeon HD 6900 Series] [1002:aa80]
Pop open
/etc/initramfs-tools/modules
and add a new line:pci_stub ids=1002:6719,1002:aa80
Rebuild the
initramfs
:sudo update-initramfs -u
Reboot and observe
pci_stub
beating outradeon
:dmesg | egrep "pci-stub|radeon" pci-stub: add 1002:6719 sub=FFFFFFFF:FFFFFFFF cls=00000000/00000000 pci-stub 0000:02:00.0: claimed by stub pci-stub: add 1002:AA80 sub=FFFFFFFF:FFFFFFFF cls=00000000/00000000 pci-stub 0000:02:00.1: claimed by stub [drm] radeon kernel modesetting enabled. radeon 0000:01:00.0: setting latency timer to 64 radeon 0000:01:00.0: VRAM: 1024M 0x0000000000000000 - 0x000000003FFFFFFF (1024M used) radeon 0000:01:00.0: GTT: 512M 0x0000000040000000 - 0x000000005FFFFFFF
Enjoy bluescreen-free VGA passthrough!
Using genpfault answer as reference, I created another answer, I think is more simple.
The first step is the same as above:
Then I created a file called /lib/modprobe.d/pci-stub.conf, whith the args I found:
options pci-stub ids=1002:9715,1002:970f
Then I created a file called /lib/modprobe.d/drm.conf, with softdep:
softdep drm pre: pci-stub
This way, when the boot process tries to load drm, first loads pci-stub, which reserves the hardware of one video card, and prevents drm to attach to some device.
Later you can remove the reservation in rc.local, modprobe -r pci-stub
.
Optionally you can load another module modprobe another-module
for that card.