Re: dual monitor setup fails (xrandr: Failed to get size of gamma for output default; warning: output LVDS not found; ignoring; warning: output VGA not found; ignoring)

[Camaleón <noelamac@gmail.com>]

On Sat, 18 Dec 2010 14:06:25 +0900, Dietrich Bollmann wrote:

> Since a couple of weeks my dual monitor setup fails:
> 
> # xrandr --output LVDS --output VGA --right-of LVDS --primary
> 
> xrandr: Failed to get size of gamma for output default warning: output
> LVDS not found; ignoring warning: output VGA not found; ignoring

Review your "/var/log/Xorg.0.log" file to find out what outputs is 
detecting Xorg. You can also run "xrandr -q" to discover what is 
connected.

Note that LVDS and VGA names can be different if you are using a KMS 
enabled intel video driver (LVDS1/VGA1).

> xrand without parameters produces the following output:
> 
> # xrandr
> 
> xrandr: Failed to get size of gamma for output default Screen 0: minimum
> 640 x 480, current 1280 x 1024, maximum 1280 x 1024 default connected
> 1280x1024+0+0 0mm x 0mm
>    1280x1024       0.0*
>    1024x768        0.0
>    800x600         0.0
>    640x480         0.0
> 
> What can I do?

It seems the external display is not being detected. Your xorg log should 
contain more data.

> I erased the /etc/X11/xorg.conf as x windows didn't start anymore and
> this was the only way I found to make it start again and get back to
> work. Trying after to reconfigure xserver-xorg with
>   dpkg-reconfigure xserver-xorg
> didn't recreate /etc/X11/xorg.conf. Could this be related?

locate xorg.conf

After running the above command ("dpkg-reconfigure xserver-xorg"), your 
"xorg.conf" file should be created under root's home (/root/
xorg.conf.new), if you want to make use of it, you'll have to move it to 
the right folder.

Greetings,

-- 
Camaleón