[ILUG] [OT] Dumb newbie X question

[Kenn Humborg]

On Fri, Mar 17, 2000 at 04:55:29PM +0000, Niall wrote:
> On Thu, Mar 16, 2000 at 10:06:52PM -0500, D ONeill wrote:
> > Hello All:
> > 
> > Here it is: I use laptops almost exclusively, but did buy a 17" CTX monitor
> > the other day. I would like to run it off the VGA port on the laptop...but
> > at a different resolution.
> > 
> > Must I run two X servers simultaneously? Is it even possible?
> 
> No - No. That is, it's not possible with a laptop, which has one graphics
> device. Usually, the VGA output is just a separate output from the LCD. Most
> modern laptops allow simultaneous use of VGA and LCD though earlier ones did
> not. It is often possible to drive the chipset at a higher resolution than
> the LCD can support, in which case you get to use the monitor only.

I'd guess that it is possible.  For example, for a while, I was running
two X servers on my PC which has only one graphics card.  The first one
to start appeared on console 7 (Ctrl-Alt-F7) and the second on console 8.

I can't see any reason why you can't do this on a laptop as well.  If one of
the servers runs at a resolution that the LCD can't handle, then you'll just
get a blank LCD, but the monitor output should still be fine.

Here's how I did it (RH5.2, I use xdm):

avalon:/etc/X11/xdm$ cat Xservers
# This file should contain an entry to start the server on the
# local display; if you have more than one display (not screen),
# you can add entries to the list (one per line).
:1 local /usr/X11R6/bin/X :1
:0 local /etc/X11/xdm/StartServerDelay 10 /usr/X11R6/bin/X

avalon:/etc/X11/xdm$ cat StartServerDelay
#!/bin/sh
sleep $1
shift
exec $*

The trick is to make sure that the servers start up in sequence, otherwise
they end up fighting over the video hardware and things can get very 
screwed up.  Hence the 10-second delay.

One caveat...  This kind of arrangement sucks RAM bigtime.  Especially if
you run a Netscape on each server simultaneously.

Later,
Kenn