Changing from KDM to lightdm

According to the Plasma 5 instructions I should use lightdm instead of KDM. I installed lightdm-kde-greeter but it still uses KDM.

I’ve tried changing /etc/sysconfig/displaymanager to lightdm, but that didn’t work.

It actually does work but you have to restart xdm.

Switch to terminal (ctrl+alt+f1), login as root and issue

rcxdm restart

That’s not true.
You can just as well use KDM with Plasma 5.

The only problem is that Plasma 5 is not installable at the same time as KDE4’s workspace including KDM, but I created packages (for Factory and 13.1) that rectify this and allow you to install Plasma 5 alongside KDE4 and KDM.
See here for how to install them:
http://forums.opensuse.org/showthread.php/499607-KDE5?p=2654365#post2654365

You can then just switch between KDE4 and Plasma 5 on the login screen, including KDM.

The instruction explicitely say to not use GDM, because with the GDM version (3.12) in Factory apparently neither KDE4 nor Plasma 5 work at the moment. Access Denied
The GDM from 13.1 (3.10) is fine though.