Comment # 18
on bug 59431
from Seth Forshee
(In reply to comment #15)
> Ok, this is the apple gmux. The display is connected to the discrete radeon
> GPU and you need to manually switch it over to the igfx (using the mux).
> That it is blank upon booting is because not only is the video muxed, so are
> the control lines which are still being reversed engineered as to how to
> setup the gmux.
I got pointed at this bug since the gmux came up.
Chris: I don't really understand this comment. I can't see that anything is
trying to switch gpus. There are likely problems getting i915 to correctly
detect which outputs are attached since the display is muxed to the radeon at
boot and macs have a bad habit of not supplying VBTs, but i915 still shouldn't
oops (but it sounds like this is fixed?), and radeon should still be able to
drive the panel.
William: I don't think I have a clear handle on the current state of this
problem. Am I correct in understanding that you no longer get the stack trace
on the screen when you boot an i386 kernel, but get a blank screen instead?
Does the behavior change at all in 3.8 based on whether or not you pass
i915.disable=1?