documentation/docs/gentoo-desktop-setup/graphical-session/session-manager.md

Session management is necessary for tracking and giving rights to certain users. For a functional setup install both elogind and turnstile and enable their corresponding services.

sh# emerge -av elogind turnstile
sh# rc-update add elogind boot
sh# rc-update add turnstiled

Then configure pam to turnstile to track the user:

...
session optional    pam_turnstile.so

When a user logs in it should now be able to start a graphical session. This should be done with:

sh$ dbus-run-session -- <window_manager>