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[vox-tech] dual head / xrandr help
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[vox-tech] dual head / xrandr help


I have a laptop that I occasionally dock and would like to mirror the built-in screen to an external monitor connected to the dock. I tried Xinerama, but it froze X. It seems like the xrandr command is a good workaround - I can use it to enable the external monitor when I dock the laptop. However, I have one little problem.... xrandr doesn't know about my external monitor's widescreen resolution:

cmclaugh@ubuntu:~$ xrandr
Screen 0: minimum 320 x 200, current 1440 x 900, maximum 1440 x 1440
VGA disconnected (normal left inverted right)
LVDS connected 1440x900+0+0 (normal left inverted right) 303mm x 190mm
1440x900 60.0*+
1280x800 60.0
1280x768 60.0
1024x768 60.0
800x600 60.3
640x480 59.9
TMDS-1 connected 1280x800+0+0 (normal left inverted right) 0mm x 0mm
1280x800 60.0*
1280x768 60.0
1024x768 60.0
800x600 60.3
640x480 59.9
TV disconnected (normal left inverted right)

I read the xrandr man page and found the --newmode switch. But I'm not sure how to use it. In particular, I don't know the <clock Mhz> <hdisp> <vdisp> and other values for my external monitor.

After a little googling, I found the gtf command. I suppose it will tell me how to find the values I need... But I don't know what to make of it's output:

cmclaugh@ubuntu:~$ gtf 1650 1050 60

# 1648x1050 @ 60.00 Hz (GTF) hsync: 65.22 kHz; pclk: 144.01 MHz
Modeline "1648x1050_60.00" 144.01 1648 1752 1928 2208 1050 1051 1054 1087 -HSync +Vsync


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