[ubuntu-x] System compositor - start X before login

[darxus at chaosreigns.com]

Thinking about what the boot process would look like with a wayland system
compositor, it occurred to me X could be started, as the last logged in
user, before the user logs in.  As soon as lighDM finishes loading and
fires the signal to fade from boot splash to lightDM.  Once a user logs in,
if it's the same user, just fade to X once it's loaded.  If a different
user logs in, kill off X, start it with the right user, and fade in when
loaded.

A little more involved, you could kill / restart X as soon as the username
is entered.

If you kill X gracefully, and wait for it to shut down before restarting
it, that could lengthen the effective boot process a significant portion of
the time in cases where different users are often logging in.  Although you
could automatically detect that case on that system and store a flag on the
filesystem to skip this.

Alternately, you could spawn the new instance of X with the correct user
before waiting for X to shut down gracefully, but then you get a different
display number, which I'm sure would annoy some percentage of users.  

Or you could just kill -9 everything.  Might not be horrible.

And I'm sure there are cases where people have browsers automatically
launching which, as a result of automatically launching and killing X
periodically, would result in their browser starting up complaining about
having been shutdown uncleanly no matter which above method was used.
Which somebody might care about.  

But I think it could take a nice chunk out of effective boot time, and
generally be fun.

-- 
"Just because you're offended, doesn't mean you're right." - Ricky Gervais
http://www.ChaosReigns.com