kdm detects most available window managers and desktop environments when it is run. Installing a new one should make it automatically available in the kdm main dialog's submenu.
If you have a very new window manager, or something that kdm does
not support, the first thing you should check is that the executable to be
run is in the
PATH and has not been renamed by the distributor
into something unexpected.
If the case is that the session type is not supported by kdm yet (maybe because it is too new), you can quite easily add it.
The session types are defined by .desktop files
located in the directories listed in
last named directory contains the system-provided default session types
in an installation from source. Software upgrades will typically overwrite
anything in here, so it is unwise to use it for configuration purposes.
Instead, a separate configuration directory should be listed first. It is
in an installation from source, but distributors often change it to something
You can simply add an appropriately named
.desktop files here. The fields are:
[Desktop Entry] Encoding=UTF-8 This is fixed to
UTF-8and may be omitted Type=XSession This is fixed to
XSessionand may be omitted Exec=
executable namePassed to eval exec in a Bourne shell TryExec=
executable nameSupported but not required Name=
name to show in the kdm session list
There are also three “magic” types:
The default session for kdm is normally KDE but can be configured by the system administrator.
The Custom session will run the user's ~/.xsession if it exists, falling back to the default session otherwise.
Failsafe will run a very plain session, and is useful only for debugging purposes.
To override a session type, copy the .desktop file from the data dir to the config dir and edit it at will. Removing the shipped session types can be accomplished by “shadowing” them with .desktop files containing Hidden=true. For the magic session types no .desktop files exist by default, but kdm pretends they would, so you can override them like any other type.