Support for laptops with 2 GPUs in the greeter
@yrro
Submitted by Sam Morris Link to original bug (#795036)
Description
I've got a Lenovo P50 with two GPUs in muxless configuration. The internal display is connected to the integrated graphics, and the external display ports are connected to the discrete NVIDIA graphics card.
Booting up while docked (with external display attached) results in the system going to sleep once GDM starts.
Even with the lid open, the greeter is only displayed on the internal display.
Under Xorg, it's possible to get the external displays working within a user session by running e.g. 'xrandr --setprovideroutputsink nouveau modesetting'. AIUI, there's no way to do this with wayland. For this reason, some work was done to ensure that the user session launched on such a laptop uses Xorg and not Wayland (bug 771442). This doesn't appear to happen for the greeter itself, and I have to set WaylandEnable=false in /etc/gdm3/custom.conf, and then manually run 'XAUTHORITY=/run/user/117/gdm/Xauthority DISPLAY=:0 xrandr --setprovideroutputsource ...' to get the external display to activate in the greeter.
Even though the external display is activated, it only displays the greeter background; the login area is still only displayed on the internal display.
Version: 3.28.x