Sucess with dual monitors

Marius Gedminas marius at
Sat Jun 24 17:00:06 UTC 2006

On Sat, Jun 24, 2006 at 09:13:39AM +1000, Jean Hollis Weber wrote:
> phenix777 wrote:
> >So, I figured out how to reload X (I think).  I press ctrl-alt-F1 to
> >switch to command line and ctrl-alt-F7 to reload X.
> Did you do these steps on the command line (F1) screen? I don't 
> know much about it, but I don't think just switching between the 
> two will reload X.

It won't.

> Quoting from a note from Daniel Carrera:
> Kill X and then start it again (note: gdm == "Gnome Display 
> Manager").
> sudo killall gdm
> sudo gdm

Better use

  sudo /etc/init.d/gdm restart

> >Now, what happens???  Nothing.  X works fine but I still have two
> >mirrored monitors, just like before.  I want one large desktop. 
> >Perhaps this has to do with xinerama?  I'm just not sure.
> Have you installed xinerama? If not, dual screens won't work.
> sudo aptitude install xinerama

What???  There is no package called 'xinerama' in Ubuntu.

Xinerama is an X server extension.  You can enable it in the
/etc/X11/xorg.conf file.

If you have two Screen sections (and two Device sections), and have
Xinerama disabled, you will get two independent screens and you won't be
able to move windows between them.  If you have Xinerama enabled, you
will have one large desktop spanning both monitors, and you'll be able
to move windows around freely.

If your two monitors show the same picture, then enabling/disabling
Xinerama will do nothing -- you need to tell X to use two screens first.

(There's an alternative way called MergedFB, but it is supported only by
some of the video drivers, e.g. radeon.  i810 does not support it.)

The easiest way to achieve this is to find someone who has the same
video card, has dual-head configured, and runs the same version of
Ubuntu, and ask them for their xorg.conf file.

I have a Radeon Mobility 7500 and my xorg.conf is at

Marius Gedminas
main(k){float i,j,r,x,y=-16;while(puts(""),y++<15)for(x
=0;x++<84;putchar(" .:-;!/>)|&IH%*#"[k&15]))for(i=k=r=0;
/* Mandelbrot in ASCII. */
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