/usr/share/lightdm/lightdm.conf.d/90-nvidia.conf is in nvidia-prime 0.8.2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | [SeatDefaults]
# Force using traditional X
type=xlocal
# Scripts to handle PRIME
display-setup-script=/sbin/prime-offload
display-stopped-script=/sbin/prime-switch
|