The Plasma Login Manager support has been merged into Ni! OS.

If you want to use it, there are two prerequisites:

1. you are using Wayland, not X11; and
2. you are on unstable NixOS.

It is in the “works for me” state. I don’t use auto-login, virtual keyboard, etc.

Going unstable

If you are on the stable channel, which would surprise me as you’re reading this post, it is easy to switch to unstable just by running these commands as root user (sudo, or su, or…).

nix-channel --add https://channels.nixos.org/nixos-unstable nixos
nix-channel --update
nixos-rebuild switch --upgrade 

This will switch you to the unstable version of NixOS.

Mind that, as NixOS is an immutable distribution, you can easily boot back into the stable version – the previous version of your system is still accessible in the bootloader menu.

Switching from SDDM to the Plasma Login Manager

There’s a new option in Ni! OS called experimental.use_plasma_login_manager. The only thing you need to do in order to switch from SDDM to the Plasma Login Manager is to set it to true, and just switch your setup to the new configuration with:

nixos-rebuild switch

Switching back is also trivial – just change the value back to false and do the switch again.

There and back

One new thing in Ni! OS is a custom label for the versions of the system (derivations in NixOS terminology).

If you enable an experimental feature such as the Plasma Login Manager, the label will clearly denote that. It makes it easy to get back to a version without the experimental features enabled.

As you can see in the following screenshot, the default label is kde-ni-os and all enabled experimental features are appended to it – when enabling the Plasma Login Manager, the label becomes kde-ni-os:plasma-login-manager. These labels can be seen in the following screenshot: