Michele Bert wrote:
2015-04-08 3:42 GMT+02:00 Trent W. Buck <trentbuck@gmail.com>:
At least xdm starts *before* the X server. It's xdm that *starts* the X server.
I've neve gone into details, but that's a question which sometimes comes up in my mind: how does a graphical DM render images on the screen? Does it interface with some drivers, or with an X-server? In the second case X starts before the DM (and it's then restarted by the DM).
I assume the logic is something like run X in the background (root gets the MIT cookie) wait until it's "up" connect to it over X do a bunch of X requests to draw the greeter <pam auth magic> put the MIT cookie where the user can read it close the greeter window spawn a user-owned process running /etc/X11/Xsession IOW it draws the greeter by talking X to the X server. I'm 100% certain that's how xdm and gdm2 work. I'm not as confident about others, but using directfb or something would be silly.