Can't switch anymore from Intel to NVIDIA GPU

Solution 1:

As you get the following error:

Error: alternatives are not set up properly

You may try to set the alternatives yourself.

When I switch to Intel I see:

update-alternatives: using /usr/lib/nvidia-331-prime/ld.so.conf to provide /etc/ld.so.conf.d/x86_64-linux-gnu_GL.conf (x86_64-linux-gnu_gl_conf) in manual mode
update-alternatives: using /usr/lib/nvidia-331-prime/alt_ld.so.conf to provide /etc/ld.so.conf.d/i386-linux-gnu_GL.conf (i386-linux-gnu_gl_conf) in manual mode

When I switch to NVIDIA I see:

update-alternatives: using /usr/lib/nvidia-331/ld.so.conf to provide /etc/ld.so.conf.d/x86_64-linux-gnu_GL.conf (x86_64-linux-gnu_gl_conf) in manual mode
update-alternatives: using /usr/lib/nvidia-331/alt_ld.so.conf to provide /etc/ld.so.conf.d/i386-linux-gnu_GL.conf (i386-linux-gnu_gl_conf) in manual mode

So you could try this to switch to Intel:

sudo update-alternatives --set x86_64-linux-gnu_gl_conf /usr/lib/nvidia-331-prime/ld.so.conf
sudo update-alternatives --set i386-linux-gnu_gl_conf /usr/lib/nvidia-331-prime/alt_ld.so.conf

Obviously you should replace 331 by your own version.

Now you could try a few things to trigger the switch:

• Log out and log in again

  to restart the X server as you normally would do

• Reboot your whole PC

  for the same purpose of the above

• Execute sudo prime-select nvidia

  as your alternatives are now set for Intel, I hope this will also fix any other settings so that everything is as it should be again (obviously you should still restart the X server)

I hope that I've interpreted the error right.

Also, you could use prime-select query to check which card is currently selected, and fix the alternatives for that card (for example NVIDIA) as you may somehow have set alternatives for the other card (for example Intel), but the tool is still thinking that you're using the other card (for example NVIDIA), thus giving an error saying that the alternatives are not set up properly.

Solution 2:

I think I've found a workaround at least.

It's all about update-alternatives.
I've noticed that both

sudo update-alternatives --config i386-linux-gnu_gl_conf

and

sudo update-alternatives --config x86_64-linux-gnu_gl_conf

returns list containing /usr/lib/i386-linux-gnu/mesa/ld.so.conf or similar.

Somehow after every reboot /usr/lib/i386-linux-gnu/mesa/ld.so.conf was set as choosen even if I've changed it before manually.

I tried changing the order on that list, but finally the solution was to remove it by

sudo update-alternatives --remove x86_64-linux-gnu_gl_conf /usr/lib/x86_64-linux-gnu/mesa/ld.so.conf

and

sudo update-alternatives --remove i386-linux-gnu_gl_conf /usr/lib/i386-linux-gnu/mesa/ld.so.conf

That should be enough.
If not, set both 'i386' and 'x86_64' to the same option by

sudo update-alternatives --config x86_64-linux-gnu_gl_conf

and

sudo update-alternatives --config x86_64-linux-gnu_gl_conf

Reboot afterwards.

You can always restore it to original state by

sudo update-alternatives --install /etc/ld.so.conf.d/i386-linux-gnu_GL.conf i386-linux-gnu_gl_conf /usr/lib/i386-linux-gnu/mesa/ld.so.conf 500  

and

sudo update-alternatives --install /etc/ld.so.conf.d/x86_64-linux-gnu_GL.conf x86_64-linux-gnu_gl_conf /usr/lib/x86_64-linux-gnu/mesa/ld.so.conf 500

Hope that it will also work for You.