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#1 2020-03-18 02:22:01

phoenix23
Member
Registered: 2020-03-17
Posts: 4

[SOLVED]Help with external monitor and PRIME/specify which display DM

Have a laptop with a AMD CPU with integrated graphics (Ryzen 7 3750, and a discrete Nvidia GPU (GTX 1660 Ti). I managed to (I think) get all the drivers working properly so that I can use the dGPU with prime-run, but I'm having trouble getting an external display to work.

Originally (after getting prime-run working), the external display was not detected at all. xrandr and "KDE System Settings > Display and Monitor" both only reported the laptop's display. After creating a config file

$ cat /etc/X11/xorg.conf.d/10-nvidia-drm-outputclass.conf 
Section "OutputClass"
    Identifier "nvidia"
    MatchDriver "nvidia-drm"
    Driver "nvidia"
    Option "AllowEmptyInitialConfiguration"
    ModulePath "/usr/lib/nvidia/xorg"
    ModulePath "/usr/lib/xorg/modules"
    Option "PrimaryGPU" "yes"
EndSection

it successfully detects both displays. KDE even still reports that the laptop display is the primary display, which I want.

The issue with this setup is that sddm now displays only on the external display, even when no display is plugged in to the laptop, which means I can't really log in without having a second display, which kind of defeats the whole purpose of having a laptop.

Is there any way for me to specify which display sddm should use? Alternatively, if some other DM would work better, which one? While I like Plasma, I'm definitely not attached to sddm if something else will work better for me.

Last edited by phoenix23 (2020-03-22 01:12:52)

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#2 2020-03-18 09:01:46

V1del
Forum Moderator
Registered: 2012-10-16
Posts: 9,074

Re: [SOLVED]Help with external monitor and PRIME/specify which display DM

While primarily intel centric, this should work: https://wiki.archlinux.org/index.php/NV … timus#SDDM

Last edited by V1del (2020-03-18 09:03:02)

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#3 2020-03-18 20:24:18

phoenix23
Member
Registered: 2020-03-17
Posts: 4

Re: [SOLVED]Help with external monitor and PRIME/specify which display DM

Well that made sddm mirror on both displays, which is fine, but now Plasma is being weird. The first time I booted, the two displays were overlaid, with neither of them showing a background or the plasma panel at the bottom. I opened Display Configuration and the two displays were on top of each other. I moved them so they're properly oriented and everything started working correctly, with the laptop display having my background and the plasma panel.

After rebooting again, I was back to both screens having no background with no plasma panel, but Display Configuration is still how I set it previously. Even unplugging the external monitor doesn't fix it. The only thing that does is rebooting without an external display attached and connecting it after logging in, which I guess I can live with.

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#4 2020-03-19 00:08:49

V1del
Forum Moderator
Registered: 2012-10-16
Posts: 9,074

Re: [SOLVED]Help with external monitor and PRIME/specify which display DM

if you redefine the second xrandr call so it properly sets up the monitors how you want them to be that should work as well.

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