KDM

About

KDM stands for KDE Display Manager. It creates an X session when started and presents a graphical login screen that allows the user to login to their choice of desktop/window manager. Its package name is kde-base/kdm in the portage tree.

Benefits

When KDE has been started by KDM, the logout menu item in the K menu will allow the user to shutdown and restart the computer as well. In addition, KDM has a 'fast user switching' equivalent- it will allow the user to spawn a new X session and login there, and users can switch back-and-forth using both normal VT switching or KDE's menu.

Starting another Desktop Environment (like GNOME) session from KDM

If you have another Desktop Environment installed and are using KDM, it is possible that it does not appear in the list of sessions available to you within KDM. If it does not, ensure that the appropriate .desktop file is in /usr/share/xsessions. You can do this by copying DesktopEnvironment.desktop across from /usr/kde/<your-version>/share/apps/kdm/sessions.

For example, if using GNOME:

cp /usr/kde/<your-version>/share/apps/kdm/sessions/gnome.desktop /usr/share/xsessions

If gnome-session is not in your $PATH, you may need to edit gnome.desktop so that it points to wherever gnome-session is located - for example:

Exec=/usr/bin/gnome-session