Correctly configuring dual head

Christoph Bartoschek bartoschek at
Wed Jul 2 07:29:54 PDT 2008


I have problems to correctly configure my dualhead setup. I am using the 
default software of Opensuse 11.0. I have a laptop with a 1400x1050 (121 DPI)  
internal display and an external monitor with 1600x1200 (100 DPI).

I would like to have the following configuration:

1. If the external display is attached I want 1600x1200 with 100 DPI.
2. If there is no external display I want 1400x1050 with 121 DPI.

Additionally I would like to rotate the external display if possible. How can 
I achieve this?

I've tried the setup at  The 
xorg.conf is: 

The resulting logfile is:

The problems are:

1. Only 1400x1050 are shown. There is no way to get the full virtual desktop 
on the external screen.
2. On some starts the display is flickering
3. The server uses 66 DPI.

After lots of trial and error I got the following xorg.conf:

with the following logfile:

Here I can switch between 1400x1050 and 1600x1200 but:

1. The DPI settings do not change.
2. The laptop always starts with 1600x1200 even without an external monitor.
3. The visible screen cannot be rotated. The output of xrandr -o left

X Error of failed request:  BadMatch (invalid parameter attributes)
  Major opcode of failed request:  154 (RANDR)
  Minor opcode of failed request:  2 (RRSetScreenConfig)
  Serial number of failed request:  12
  Current serial number in output stream:  12

xrandr --verbose gives me:

Screen 0: minimum 1400 x 1050, current 1600 x 1200, maximum 1600 x 1200
default connected 1600x1200+0+0 (0x4d) normal (normal) 0mm x 0mm
        Identifier: 0x4c
        Timestamp:  28128
        Subpixel:   horizontal rgb
        CRTC:       0
        CRTCs:      0
  1600x1200 (0x4d)   74.9MHz *current
        h: width  1600 start    0 end    0 total 1600 skew    0 clock   
        v: height 1200 start    0 end    0 total 1200           clock   39.0Hz
  1400x1050 (0x4e)   73.5MHz
        h: width  1400 start    0 end    0 total 1400 skew    0 clock   
        v: height 1050 start    0 end    0 total 1050           clock   50.0Hz

Is there a way to solve the problems and get a usable setup? Where do I have 
to look? 


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