Bug#689268: linux-image-3.2.0-3-amd64: Intel HD 4000 (Ivy Bridge) graphics freeze

[Ingo <ingo.steiner@gmx.net>]

>> But since then I have never obseved any cras/freeze for days now.
> 
> Keeping my fingers crossed for the same outcome.
> 
> /Per
> 

Still ok here - good luck.

Me came up another thing which probably relates to that. As far as I
could extract from internet searches regarding this issue, I concluded:

1. i915 drm driver uses kms and additionally requires framebuffer support.

2. for normal graphics operation and 3D acceleration it uses
 "agp" communication (use of "mtrr" is depreciated).

3. however framebuffer seems to use "mtrr" for communication.

So finally both have to match somehow or properly switch over.

When the problem/freeze occurred I had beforehand booted into my service
system which is a minimal Wheezy without graphics, just terminal. This
of course just uses framebuffer.

Maybe the this switching also triggered the freeze?

This is just a guess from me, beeing definitely no expert in Linux and I
do not have any idea of the internals of driver or kernel.