Ubuntu
xserver-xorg-video-intel package

  1. Bug #158415
  2. Comment #15

Comment 15 for bug 158415

Revision history for this message
unggnu (unggnu) wrote : Re: widescreen resolution isn't recognized for external monitor after hotplugging but after X start [i915]

I think I have found a solution. According to http://www.thinkwiki.org/wiki/Xorg_RandR_1.2#xorg.conf Virtual Size should be set to 2048x2048 (maximum possible 3D accelerated resolution for Intel chips) in xorg.conf.
If I do this hotplugging of the widescreen monitor works fine. Xrandr shows the correct resolution. So it seems that Xorg sets an Virtual size on start which is as high as the needed resolution (x resolution value * x resolution value) but if a Display with a higher resolution is connected it can only use resolutions which are the same or lower than the virtual one.
There are two possible solutions imho.
Xorg should use the maximum virtual size if it doesn't need so much mem or the better one: Xorg should be able to change the virtual size on the fly if a monitor with a higher resolution is hotplugged.