system freezes after loading gdm/gnome

[Bruno Wolff III]

On Thu, Feb 28, 2013 at 13:42:56 -0800,
   Richard Vickery <richard.vickeryrv at gmail.com> wrote:
>On Thu, Feb 28, 2013 at 11:31 AM, Jan Dvořák <mordae at anilinux.org> wrote:
>
>> > > Do you see the same problem starting KDE instead?
>> >
>> > I will try again with something that does not use cogl and with
>> > disabled rc6, now that I have btrfs root with snapshots.
>>
>> Both KDM and Xfce4 work flawlessly.
>>
>> I have tried with i915.i915_enable_rc6=0 and there was no difference.

Likely the output of:
cat /proc/cmdline

This tells what parameters where used at boot on the kernel command line.