Comment # 41 on bug 1207314 from Ra���l Osuna

(In reply to Pablo Sanchez from comment #40)
> (In reply to Ra���l Osuna from comment #39)
> > [ trimmed ] 
> >
> > sudo init 3
> > sudo /usr/sbin/prime-select offload
> > reboot
> 
> Hi Ra���l,
> 
> I wanted to thank you for posting the above:  Thank you!
> 
> It seems to have solved my issue!  \o/
> 
> I have rebooted my computer five/six times and now SDDM is happily
> presenting a log in screen.  Before, I'd only get a cursor.  My only
> recourse was to kill Xorg from a virtual console.

Glad it helped!

For me, the issue came back the following day. But it seems stable again after
adding the prime-select service to systemd, it was disabled:

# sudo systemctl enable prime-select.service 

Whether this should be on by default, I don't know, but I don't remember having
messed up with the service myself (although if I did that at installation time,
6 months ago, I would not remember, but since then, I haven't touched that
service for sure.