Can I force VGA signal output even when xrandr shows 'disconnected'?

Question

My notebook is connected to a HDTV through a KVM Switch (one other notebook also connected to the same HDTV). The problem seems to be that Ubuntu doesn't recognize the HDTV to be turned on and therefore doesn't enable the VGA output. As far as I understand it has something to do with EDID information not being send trough the KVM Switch.

xrandr won't enable the VGA output through xrandr --output VGA1 --auto, it just keeps showing as disconnected.

Can I somehow force the VGA port to send a signal?

My Graphics Controller:

Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03)

Answer 1

Yes,you can , but --auto is doing the right thing. Instead do something like:

xrandr --addmode VGA1 1024x768
xrandr --output VGA1 --mode 1024x768 --right-of LVDS1

Answer 2

I had problems with some VGA cables that has DDC (display data channel) broken or not connected. I found this useful workaround using boot parameter to force kernel to see a disconnected VGA: video={conn}:{res}e conn should match xrandr device name res 1024x768 (or what ever you prefer) e means to enable the port (even if no device/monitor is detected).

See: http://distro.ibiblio.org/fatdog/web/faqs/boot-options.html