For a project that I’m currently helping with, we needed recent OpenGL features that are only available on NVIDIA drivers with version 340 and later.
Unfortunately, I have one of those NVIDIA Optimus laptops. Up to now, Bumblebee worked a treat (I would recommend this system in most cases), but for this project I needed the whole of X to run on the NVIDIA, so I had to make use of nvidia-prime to switch between Intel and NVIDIA mode.
After upgrading to the nvidia-346* packages from the xorg-edgers PPA, switching to nvidia mode by typing
prime-select nvidia and then logging out and in to X, I was greeted by a black screen.
Many hours of experimentation, script tracing and web searching later I made the following observations:
gpu-manager, part of
ubuntu-drivers-common(in my case version 1:0.2.91.7), runs every time you start and stop your display manager (in other words, when you log out and back in) and then rewrites the
/etc/X11/xorg.confbased on what it finds in the system.
- In theory, with prime support in the NVIDIA drivers,
xrandris used to connect the output of NVIDIA adapter to the Intel adapter, which then displays the output. See the NVIDIA driver documentation for more details. The
/usr/share/lightdm/lightdm.conf.d/(part of the
/sbin/prime-offload, which will automatically take care of the
xrandrsetup for you.
gpu-managerwas rewriting my
xorg.conffile incorrectly, at least according to NVIDIA’s xrandr documentation. The primary issue was that
gpu-managerwas using the
inteldriver for the intel, instead of the
All of this lead to the following (working: now tested on two setups) solution:
- Switch to console (
Ctrl-Alt-F1) and stop lightdm:
sudo service lightdm stop
gpu-managerby commenting out everything in
- Switch to nvidia mode by doing
sudo prime-select nvidia
- Change your
/etc/X11/xorg.confto look like this, making sure that the nvidia BusId is correct (check with
- In the comments, Christopher May-Townsend made this brilliant suggestion. By doing
sudo chattr +i /etc/X11/xorg.confyou can prevent any process from changing the file. We highly recommend that you do this, as users have reported that even after disabling the
gpu-managerupstart job, it still manages to change the
- Start X up again with
sudo lightdm start
If you are still greeted by a black screen, switch back to the console, and double-check that the
xorg.conf has not again been rewritten to its pre-modesetting state. (if you’ve used the
chattr trick above, you should be fine)
If you want to switch back to Intel you will have to stop
xorg.conf editable again with
sudo chattr -i /etc/X11/xorg.conf, activate intel mode with
sudo prime-select intel and then restart X with
sudo service lightdm start.
It’s very possible that later versions of
gpu-manager might have fixed this behaviour.
Let me know in the comments if this worked for you!