Auto-Resolution-Detection of External Monitor?

Alex Deucher alexdeucher at
Mon Jun 27 12:35:25 PDT 2005

On 6/27/05, Andreas Schildbach <andreas at> wrote:
> Hello everyone,
> I've configured X 6.8.2 on my Notebook in a Dualhead/Xinerama configuration.
> I have several places where I use the notebook, one with an external
> 1920 x 1200 display, one with a 1280 x 1024 display and one place is "on
>   the road" with no external display at all.
> Currently, I have to switch resolutions by hand. Is there any way to
> configure X so it automatically switches to the resolution of the
> monitor that is connected? And would perhaps shut down the secondary
> head if there is no monitor connected at all?
> Detection at boot-up time would be sufficient.
> Detection at video cable connect time (while the notebook is running)
> would be perfect.
> Regards,
> Andreas

assuming the xorg radeon driver is able to detect the attached devices
properly, you can do this now with mergedfb.  just set your
crt2position to the orientation you want and then when you start X it
will either run single or dualhead depending on what's connected.  You
can also force both heads on and switch between single and dualhead
using mergedfb and xrandr as long as you have some clone modes


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