nVidia

Xorg.0.log: (EE) [drm] Failed to open DRM device for pci

The purpose of this wiki page is to collect all possible causes leading to the given error, and offer appropriate solutions in each case.

Two concurrent X11 sessions

Example /var/log/Xorg.0.log output:


[ 834.454] (EE) [drm] Failed to open DRM device for pci:0000:0b:00.0: -2
[ 834.454] (**) modeset(0): claimed PCI slot 11@0:0:0
[ 834.454] (II) modeset(0): using default device
[ 834.454] (WW) Falling back to old probe method for fbdev
[ 834.454] (II) Loading sub module "fbdevhw"

Which linux kernel driver is being used: nvidia or nouveau?

Add here different ways to answer the above question.

With lspci

One way is to check the output of lspci:

# lspci -nnk | grep -iA2 vga
01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GM107 [GeForce GTX 750 Ti] [10de:1380] (rev a2)
        Subsystem: Gigabyte Technology Co., Ltd GM107 [GeForce GTX 750 Ti] [1458:3681]
        Kernel driver in use: nouveau

See the 3rd line: "Kernel driver in use: nouveau".

nVidia

https://wiki.gentoo.org/wiki/NVidia/nvidia-drivers
When using the nVidia drivers, it is advisable to disable the nouveau driver in the kernel configuration, as explained in the above article.
However, if desired, the nouveau driver could still be compiled as a module, and blacklist the kernel module to make sure it's not loaded at the same time as the nvidia driver.

https://wiki.archlinux.org/index.php/NVIDIA/Tips_and_tricks

Troubleshooting

Nouveau drivers

https://nouveau.freedesktop.org/wiki/Bugs/
https://nouveau.freedesktop.org/wiki/TroubleShooting/

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