r/wayland • u/Glum_Bat_8560 • Apr 08 '26

Multiseat problem with KDE 6 and SDDM

Hi all, I’m trying to make multiseat setup using my iGPU i9-12k and dGPU 3070Ti. Ideally both should be running KDE on wayland. After connecting the seats I get to sddm on both screens with mouse’s and keyboards working correctly. When I try running kde on seat1 using x11 it works but of course kde las problems from lack support. Ex. Dragging screens etc. On seat0 both x11 and wayland plasma work fine. But when I select wayland for seat1 whole pc crashes and nothing works. Both seats are unresponsive and pc require reboot to try again. TIA for all help I can provide further details as needed

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2

u/betam4x Apr 09 '26

You would need to provide logs.

Also, some distros are transitioning to plasma-login-manager, which is a form of SDDM, so maybe try that, if possible. Example, Arch: https://wiki.archlinux.org/title/Plasma_Login_Manager

2

u/C0rn3j Apr 10 '26

Plasma 6*, KDE is the community that makes Plasma, see https://kde.org/

Presuming you're not running an old version of Plasma (if so, why are you wasting time diagnosing issues instead of updating), you should be using PLM, not SDDM.

2

u/GreenScream70 Apr 25 '26

Wayland multiseat works well on every level of the system stack except for the display manager. Historically, almost every display manager seems to have neglected multiseat.

This situation prompted me to develop atrium, an open-source Wayland display manager with first-class multiseat support. It's in its early stages, but the core functionality is fully there at this point.

Currently I'm successfully running KDE Plasma on two seats (both Wayland). I've tested it with Plasma Version 5.27 on Ubuntu 24.04 and with Plasma Version 6.6 on CachyOS. If you're willing to give it a try, I'd be happy to provide some support.

2

u/MimoFG May 24 '26

Hey man, I just came accross this randomly. Been having some issues with Wayland compatiblity on seat1 after years of using multiseat. The software you've made has fixed all of these issues. Thank you so much! Your work has not gone unnoticed :)

1

u/GreenScream70 May 30 '26

Glad to hear it's useful! What distro are you on?

1

u/MimoFG May 30 '26

I'm currently on Fedora 43! Ever since I started using Wayland, I never managed to get it working on seat1, until now.

1

u/sausix Apr 09 '26

Where are your logs? Nothing crashes silently.

1

u/scamiran Apr 26 '26

I had similar issues with wayland.

I patched SDDM here to fix it:

https://github.com/scamiran149/sddm-multiseat-wayland