Display manager

A display manager, sometimes known as login manager or abbreviated as DM, presents the user with a graphical login screen to start an X server session.

Display Managers in Gentoo
More than half a dozen display managers are available in the Portage tree. The following is a non-exhaustive list, presented in alphabetical order, of display managers available in the main Gentoo repository:

Configuration
In major Linux operating systems display managers are started automatically on boot. In order for this to happen automatically a script must be added to the proper init system's runlevel. Examples for OpenRC and Systemd are provided below.

Be careful to read the documentation for each display manager, as slightly different configuration will be required. For more information see the respective wiki entry for the display manager of choice.

OpenRC
Under most circumstances the OpenRC init system (Gentoo's default init system) will be used to start the display manager. The XDM init script handles the starting of the display manager. Configuration of this file is needed to set a default display manager for the system.

The following examples will set KDE to be the default display manager. Adjust as necessary for other display managers.

To start KDM on boot, add the XDM init script to the system's default runlevel:

To start KDM immediately, run:

Systemd
If using systemd as the init system, first locate a file. Some can be found in the systemd overlay, choose one that works and move it to or install  from the overlay.

To start KDM on boot, enable the following service:

To start KDM immediately run this command:

nVidia card/drivers
When you use more than one monitor, you must set the first output for the right loading in your primary screen, the nVidia users using nVidia drivers can set it right by enabling the twinview option.

this is an example of the section screen, where the primary monitor is set to the DVI output (DFP-0):

Start X without a Display Manager
See the X without Display Manager article.