Why do you need 2 Xsessions ??
  This is just for my personal knowledge ??

Selon Frederick Bruckman <fredb@immanent.net>:

> On Sat, 17 Apr 2004, Hanspeter Roth wrote:
> 
> > I'd like to run two X sessions. At least one should be launched by
> > xdm. When I run a second X session without xdm it may happen that
> > after a while the two servers interfere with each other. So I'm using
> > xdm to launch both X sessions.
> >
> > The Xservers file looks like:
> >
> > :1 local /usr/X11R6/bin/X vt06 :1 -nolisten tcp -xf86config XF86Config2
> > :0 local /usr/X11R6/bin/X vt05 :0 -nolisten tcp
> >
> > This usually causes the server on display :0 to appear first. This is
> > what is desired.
> > However sometimes the server on display :1 appears first.
> >
> > Interestingly it seems that the setup phase of the second X server
> > only starts running when the display is switched by ctl-alt-fx.
> 
> This is an old issue:
> 
>     http://www.netbsd.org/cgi-bin/query-pr-single.pl?number=8128
> 
> > How can I make sure that the server on display :0 _always_ appears
> > first?
> 
> The "vt" argument does nothing, by the way. With the recent XFree86,
> the first available virtual terminal is always chosen. However,
> because opening the virtual terminal is not the first thing the
> Xserver does, there's a race condition, so it often happens that the
> first server started gets the higer numbered terminal.
> 
> That should be the first clue that having two binaries attack the same
> video card is not a good idea. It mostly works when you're only using
> the frame buffer, because the inactive binary sleeps, and there's no
> way to fatally corrupt a frame buffer that remapping the windows can't
> fix, but if you use any other features (acceleration, X Video), some
> card resource will eventually get corrupted and hang the system.
> 
> It would be neat, though, if the one Xserver binary were smart enough
> to attach different virtual terminals as different screens on the same
> display. You could have one login, but view programs in different
> resolutions and depths on the other screens. The server would be
> expected to lock resources as appropriate, or at least only make
> certain resources available through selected screens. Just a thought.
> 
> Frederick
> 


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