Arch Linux

jatsekku

Member

Registered: 2022-01-22

Posts: 2

[SOLVED] Unable to start X server on nvidia GPU without amd GPU.

Hello guys!

I'm trying to set-up GPU passthrough on my machine and I actually kind of did, but it's not working as I would like to.

I have 2 GPU in my machine:

04:00.0 VGA compatible controller: NVIDIA Corporation GF116 [GeForce GTX 550 Ti] (rev a1)
        Subsystem: ASUSTeK Computer Inc. Device 83be
        Kernel driver in use: nvidia
--
0c:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Navi 23 [Radeon RX 6600/6600 XT/6600M] (rev c1)
        Subsystem: Micro-Star International Co., Ltd. [MSI] Device 5021
        Kernel driver in use: amdgpu

As my first attempt I used instruction from here: https://github.com/BigAnteater/KVM-GPU-Passthrough and I manged to passthrough the AMD card, but when I'm starting the VM, output of the nVidia goes black.
I decided to try with official arch guide(https://wiki.archlinux.org/title/PCI_passthrough_via_OVMF) and I stucked with first warning section under "3 Isolating GPU".
I tried to force X to use the Nvidia card with partially success.
If I have 2 my card electrically hooked-up to machine both drivers (nvidia and amdgpu) are loaded and I can use both of them by using optimus-manager:

[jatsekku@Anemone ~]$ optimus-manager --switch nvidia
[jatsekku@Anemone ~]$ glxgears -info | grep GL_REN
GL_RENDERER   = GeForce GTX 550 Ti/PCIe/SSE2
[jatsekku@Anemone ~]$ xrandr --listproviders
Providers: number : 2
Provider 0: id: 0x278 cap: 0x1, Source Output crtcs: 2 outputs: 4 associated providers: 1 name:NVIDIA-0
Provider 1: id: 0x2c0 cap: 0xf, Source Output, Sink Output, Source Offload, Sink Offload crtcs: 5 outputs: 4 associated providers: 1 name:modesetting

[jatsekku@Anemone ~]$ optimus-manager --switch integrated
[jatsekku@Anemone ~]$ glxgears -info | grep GL_REN
GL_RENDERER   = AMD Radeon RX 6600 XT (navi23, LLVM 14.0.6, DRM 3.49, 6.1.4-arch1-1)
[jatsekku@Anemone ~]$ xrandr --listproviders
Providers: number : 1
Provider 0: id: 0x47 cap: 0xf, Source Output, Sink Output, Source Offload, Sink Offload crtcs: 5 outputs: 4 associated providers: 0 name:modesetting

I also tried detaching AMD GPU (by disconnecting power supply) but then X wasn't able to load nvidia drivers.

Xorg log with AMD GPU attached:
https://pastebin.com/N0kYnBxt

Last edited by jatsekku (2023-01-09 00:07:53)