Multiseat with one virtual (hardwareless) seat


I want to run KDE with 2 parallel sessions:

  • 1 session using real hardware (monitor, keyboard, mouse)
  • 1 session using “virtual” hardware

Virtual hardware means: I want to be able to connect to that session from remote e.g. with VNC.
Both sessions need to be active in parallel.

So its similar to a multi seat configuration except that there is no physical hardware for the second seat.

How can I realize such a configuration?

I tried using lightdm instead of sddm because that supports multiseat.
I used Xvfb to start a virtual framebuffer but I don’t know how to assign it to the 2nd seat (seat1).