Hi guys,

Bit of a weird edge case here, but it has come up at least once

So I have a workstation with two video cards, each with two monitors attached. When booting from the live media this works perfectly with all monitors working as expected, however, after installation is complete the second video card doesn't work in X. It does display the boot sequence as normal, however, so it is sort of working. Looking around in Xorg.0.log I can see that it is getting permissions errors trying to access /dev/dri/card0 and card1, which it does not have those issues on the live media. The permissions of those files are root:video, but unfortunately adding the video group to the sddm user doesn't correct the issue as I had hoped.

Not sure if anyone has a work around/fix for this, but its bug that probably should get looked at because it renders multiple video card setups unusable.

EDIT: Here is a link to the Xorg.0.log file in case someone wants to have a closer look.

This sounds like a libdrm / Bumblebee related problem: https://github.com/Bumblebee-Project/Bumblebee/issues/652#issuecomment-156548041

You can find more details on google by searching for: "failed to set DRM interface version 1.4: Permission denied"

i came across a workaround on the ArchWiki which you could try: https://wiki.archlinux.org/index.php/bumblebee#.2Fdev.2Fdri.2Fcard0:_failed_to_set_DRM_interface_version_1.4:_Permission_denied

dev/dri/card0: failed to set DRM interface version 1.4: Permission denied

This could be worked around by appending following lines in /etc/bumblebee/xorg.conf.nvidia (see here):

Section "Screen"
Identifier "Default Screen"
Device "DiscreteNvidia"
EndSection

If you don't have the /etc/bumblebee/xorg.conf.nvidia file, then you can try using the nvidia settings utility to generate a xorg.conf file, copy it to /etc/X11/xorg.conf and then amend the "Screen" section(s) and add the Device line shown above in them.

Well, I'm using two Radeon cards on a desktop so that is definitely not it.