Arch LXC container irregular root permission with drm?

[wxzhao]

I successfully passed through the iGPU to the Ubuntu22 LXC container and then tried to passthrough the iGPU to Arch LXC container. After a longtime attempt. I realized that the permission of root limit my test.

When I login the tty1 as root, I don't have the real permission for the drm. But after su command, the root could get correct permission. The ubuntu22 LXC container does not have this problem.

What happened?

pve-manager/8.0.4/d258a813cfa6b390 (running kernel: 6.2.16-19-pve)
lxc/stable 1:5.0.2-1+deb12u1 amd64

Arch Linux 6.2.16-19-pve (tty1)

ArchLoginD login: root
Password:
Last login: Fri Nov 17 16:18:41 on tty1
[root@ArchLoginD ~]# vainfo
Trying display: wayland
error: XDG_RUNTIME_DIR is invalid or not set in the environment.
Trying display: x11
error: can't connect to X server!
Trying display: drm
error: failed to initialize display
[root@ArchLoginD ~]# su
[root@ArchLoginD ~]# vainfo
Trying display: wayland
error: XDG_RUNTIME_DIR is invalid or not set in the environment.
Trying display: x11
error: can't connect to X server!
Trying display: drm
vainfo: VA-API version: 1.20 (libva 2.20.0)
vainfo: Driver version: Intel i965 driver for Intel(R) Coffee Lake - 2.4.1
vainfo: Supported profile and entrypoints
      VAProfileMPEG2Simple            : VAEntrypointVLD
      VAProfileMPEG2Simple            : VAEntrypointEncSlice
      VAProfileMPEG2Main              : VAEntrypointVLD
      VAProfileMPEG2Main              : VAEntrypointEncSlice
      VAProfileH264ConstrainedBaseline: VAEntrypointVLD
      VAProfileH264ConstrainedBaseline: VAEntrypointEncSlice
      VAProfileH264ConstrainedBaseline: VAEntrypointEncSliceLP
      VAProfileH264Main               : VAEntrypointVLD
      VAProfileH264Main               : VAEntrypointEncSlice
      VAProfileH264Main               : VAEntrypointEncSliceLP
      VAProfileH264High               : VAEntrypointVLD
      VAProfileH264High               : VAEntrypointEncSlice
      VAProfileH264High               : VAEntrypointEncSliceLP
      VAProfileH264MultiviewHigh      : VAEntrypointVLD
      VAProfileH264MultiviewHigh      : VAEntrypointEncSlice
      VAProfileH264StereoHigh         : VAEntrypointVLD
      VAProfileH264StereoHigh         : VAEntrypointEncSlice
      VAProfileVC1Simple              : VAEntrypointVLD
      VAProfileVC1Main                : VAEntrypointVLD
      VAProfileVC1Advanced            : VAEntrypointVLD
      VAProfileNone                   : VAEntrypointVideoProc
      VAProfileJPEGBaseline           : VAEntrypointVLD
      VAProfileJPEGBaseline           : VAEntrypointEncPicture
      VAProfileVP8Version0_3          : VAEntrypointVLD
      VAProfileVP8Version0_3          : VAEntrypointEncSlice
      VAProfileHEVCMain               : VAEntrypointVLD
      VAProfileHEVCMain               : VAEntrypointEncSlice
      VAProfileHEVCMain10             : VAEntrypointVLD
      VAProfileHEVCMain10             : VAEntrypointEncSlice
      VAProfileVP9Profile0            : VAEntrypointVLD
      VAProfileVP9Profile0            : VAEntrypointEncSlice
      VAProfileVP9Profile2            : VAEntrypointVLD