(In reply to comment #69)
> I have an iMac 11,1 and I cannot get X to work. Documentation
> is scarce, so I don't know how to discover what is the problem.
> When I start X, it doesn't show any errors, but I get a blank
> screen. Same for when I insert the radeon module with kms on.
> I suspect that the EDID is not being handled correctly. Does
> any of you know how I can create an external EDID for a 2560x1440
> monitor? My video card is an ATI Radeon HD 4850, by the way.

If xrandr --verbose shows the appropriate modes for your display, there is no
problem with the EDID.  You might try a 3.11 kernel.