Comment 2 for bug 1757202

The bug is not related to lightdm because it also occurs with gdm3.

I have several Linux boxes with graphic cards nVidia GTX 570, GTX 670 and Quadro K2000, and the problem appears on each one, with different resolutions for the second user and sometimes with a very slow rendering.

I analyzed the Xorg logs and found that for the second user, the ModulePath is incorrectly set to "/usr/lib/xorg/modules" instead of "/usr/lib/x86_64-linux-gnu/nvidia/xorg". Thus the nvidia modules are not found when the X server starts. Note that this problem does not occur for the first user...

So, here is a workaround for this problem:

1. Create an xorg.conf file for your nVidia device. All you have to do for this is to launch the command:

sudo nvidia-xconfig

This will create a file /etc/X11/xorg.conf.

2. Edit the created file /etc/X11/xorg.conf and add at the end the lines:

Section "Files"
 ModulePath "/usr/lib/x86_64-linux-gnu/nvidia/xorg"
 ModulePath "/usr/lib/xorg/modules"
EndSection

3. Save and restart the X server. Now, for the first and second user you should have the nvidia driver in use, with the correct resolution and fast rendering. You can check it using the command:

glxgears -info |grep NVIDIA

which should return the nvidia opengl version.

Note, there is also a problem of slow scrolling in the virtual console (Ctrl-Alt-F1). To solve this, edit /etc/default/grub and set the GRUB_CMDLINE_LINUX variable as:

GRUB_CMDLINE_LINUX="video=vesafb:mtrr:3,ywrap"

then do:

sudo update-grub

and reboot. Now, the scrolling speed in the virtual console should be very fast.