how to ignore monitor's EDID?

Tomasz Chmielewski mangoo at
Sun Dec 28 04:43:57 PST 2008

I have a radeon 9600 card, with two devices connected:

- DVI: LCD monitor, capable of 1280x1024 (preferred mode)
- VGA: LCD projector, capable of 1024x768, (800x600 preferred mode)

Both devices show the same output ("clone" - of course, if the 
resolution is 1280x1024, VGA/LCD projector does not show any output, as 
this device does not support this mode).

The problem is - whenever the LCD projector is powered on as computer 
boots, X starts in 800x600 resolution.
What's worse - it's not possible to change the resolution to 1280x1024; 
xrandr will only switch the resolution up to 1024x768 (maximum supported 
by the VGA monitor).

Is it possible to force the resolution on a device, even if it doesn't 
support it?

My xorg.conf setup for this video card looks like below; "monitor0" is 
the LCD monitor; I don't have any section about the VGA output / LCD 

Section "Monitor"
     # TV fullscreen mode or DVD fullscreen output.
     # 768x576 @ 79 Hz, 50 kHz hsync
     Identifier     "monitor0"
     VendorName     "Plug'n Play"
     ModelName      "BenQ FP937s+"
     HorizSync       31.0 - 83.0
     VertRefresh     59.0 - 76.0
     ModeLine       "768x576" 50.00 768 832 846 1000 576 590 595 630
     ModeLine       "768x576" 63.07 768 800 960 1024 576 578 590 616

Section "Device"
     Identifier     "device0"
     Driver         "radeon"
     VendorName     "ATI Technologies Inc"
     BoardName      "ATI Radeon 9600"
     BusID          "PCI:01:00:0"
     Option "AccelMethod" "EXA"

Section "Screen"
     Identifier     "Screen0"
     Device         "device0"
     Monitor        "monitor0"
     DefaultDepth    24
     SubSection     "Display"
         Depth       8
         Modes      "1280x1024" "1024x768"
     SubSection     "Display"
         Depth       15
         Modes      "1280x1024" "1024x768"
     SubSection     "Display"
         Depth       16
         Modes      "1280x1024" "1024x768"
     SubSection     "Display"
         Depth       24
         Modes      "1280x1024" "1024x768"

Tomasz Chmielewski

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