From XDM manual page:
- Xdm manages a collection of X displays, which may be on the local host or remote servers. The design of xdm was guided by the needs of X terminals as well as The Open Group standard XDMCP, the X Display Manager Control Protocol. Xdm provides services similar to those provided by init, getty and login on character terminals: prompting for login name and password, authenticating the user, and running a "session."
XDM provides a simple and straightforward graphical login prompt.
# pacman -S xorg-xdm xorg-xconsole
Make .xsession executable:
$ chmod 744 .xsession
Optionally, install the Arch Linux theme for XDM:
# pacman -S xdm-archlinux xorg-xbutton
See Display Manager for additional information.