Comment 11 for bug 1428328

This is no longer a problem in sddm. There seems to be a bug in ubuntu-drivers-common (on in systemd) that prevents gpu-manager from creating the following file:

/var/lib/ubuntu-drivers-common/requires_offloading

As a result, nvidia-prime, won't see the need of offloading rendering, and you will boot into a black screen. I've filed LP: #1443364 about it.

Assuming that you're affected by the same problem, for now you can do the following:

sudo systemctl stop sddm

sudo systemctl start gpu-manager

sudo systemctl start sddm