Plasma Workspace as systemd user-session

Ultimate Goal

The ultimate goal of this project is, to make use of systemd's support for user-sessions wherever possible for running a Plasma Workspace. This support is to be implemented in a way which doesn't get in the way of legacy/cross-platform support, so running a Plasma Workspace without a systemd user-session underneath will still be possible.

What are the benefits?

Parallelized and faster startup of the Plasma Workspace after login
More finegrained control over running services
Increased stability by eliminating existing hacks in startkde, ksmserver, kdeinit, …
Cleaner definition of dependencies between Plasma Workspace components
Increased security
Greatly improved logging by using systemd's journald - goodbye horrible piece of log-target called ~/.xsession-errors
Better control over system resources/process priorities (e.g. ensure GUI elements are always responsive) via systemd's builtin cgroup control interface

Resources

user-session units for Plasma Workspace

I created some initial user-session units for Plasma Workspace which can be found on GitHub.

Unsorted items

This is a collection of items, notes and other things which need to be taken care of. They need to be investigated and properly documented.

ksmserver

ksmserver does a lot of ugly (from systemd's perspective) things which need to be evaluated:

tries to start a WM in ksmserver/startup.cpp → launchWM which should be left to systemd
doesn't register itself as session leader via systemd-logind which breaks a lot of session related functionality. Documented in bug#335390

ksplashqml

Relies on a serial startup of the components, but isn't able to deal with a parallelized startup. If the final result is a really fast startup, a splash screen might be not needed anymore. If the startup still takes "enough" time to show a splash screen, ksplashqml needs to be reworked to be able to deal with a parallelized startup.