Get it into SDDM

You will need your newly built-from-source version of Plasma appear to in the SDDM login screen's Sessions menu, allowing you to log into it. To do this, run the following command:

sudo ~/kde/build/plasma-workspace/login-sessions/install-sessions.sh

After that, you can log out and select your new plasma session in SDDM's session chooser menu (which is located in the bottom-left corner of the screen if you're using the Breeze SDDM theme)

Quirks

KAuth & Polkit applications

Note

This step is optional, but you will need to do it if you want to develop or use apps that display password dialogs.

Because we installed Plasma to a custom path, KAuth and Polkit need to be made aware of your new Plasma installation. Run the following commands:

sudo ln -s /home/$USER/kde/usr/etc/dbus-1/system.d/*  /etc/dbus-1/system.d/.
sudo ln -s /home/$USER/kde/usr/etc/polkit-1/rules.d*  /etc/polkit-1/rules.d/.

DBus

Note

This step is optional, but your Plasma session may experience quirky behavior without it.

Just like KAuth and PolKit, DBus is not aware of your new Plasma installation and needs to be informed. Unfortunately, unlike Kauth and PolKit, DBus can only be given one path at a time, so you will need to change the path that DBus looks at whenever you use your new Plasma session. Create a file /etc/dbus-1/session-local.conf.bak with the following contents:

<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
 "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<busconfig>
<servicedir>/home/$USER/kde/usr/share/dbus-1/services</servicedir>
</busconfig>

Create another file /etc/dbus-1/system-local.conf.bak with the following contents:

<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
 "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<busconfig>
<servicedir>/home/$USER/kde/usr/share/dbus-1/system-services</servicedir>
<includedir>/home/$USER/kde/usr/etc/dbus-1/system.d</includedir>
</busconfig>

Before logging into your new compiled-from-source Plasma session, rename the files like so:

sudo mv /etc/dbus-1/session-local.conf.bak /etc/dbus-1/session-local.conf
sudo mv /etc/dbus-1/system-local.conf.bak /etc/dbus-1/system-local.conf

Then before you log out and return to your normal distro-provided Plasma session, rename them like so:

sudo mv /etc/dbus-1/session-local.conf /etc/dbus-1/session-local.conf.bak
sudo mv /etc/dbus-1/system-local.conf /etc/dbus-1/system-local.conf.bak