Comment # 40 on bug 42373 from Kunal

(In reply to comment #37)
> (In reply to comment #36)
> > (In reply to comment #35)
> > > Did you tested 3.7 kernel ? Bunch of patch went in some might help your case.
> > 
> > No, not yet.
> > Will build and test a 3.7-rc1 based kernel and report back.
> > 
> > Thanks,
> > Kunal
> 
> OK, didn't get time to try 3.7-rc1. So, instead, installed 3.7-rc5 based
> Ubuntu kernel from:
> http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.7-rc5-raring/
> 
> (specifically, following files:
> http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.7-rc5-raring/linux-headers-
> 3.7.0-030700rc5-generic_3.7.0-030700rc5.201211110835_amd64.deb
> 
> http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.7-rc5-raring/linux-headers-
> 3.7.0-030700rc5_3.7.0-030700rc5.201211110835_all.deb
> 
> http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.7-rc5-raring/linux-image-3.
> 7.0-030700rc5-generic_3.7.0-030700rc5.201211110835_amd64.deb
> 
> http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.7-rc5-raring/linux-image-
> extra-3.7.0-030700rc5-generic_3.7.0-030700rc5.201211110835_amd64.deb
> )
> 
> With this, situation is no better. In fact, with this kernel, I cannot even
> switch to a tty to restart X - which works happily on my current
> 3.2.0-32-generic
> (package: "linux-image-3.2.0-32-generic" version: "3.2.0-32.51").
> 
> There is no significant message logged in the syslog with 3.7-rc5 which can
> point to a problem. Attaching the dmesg output and Xorg log anyways.
> 
> Thanks,
> Kunal

One more point to note:
Whenever I try to reboot from 3.7-rc5 into 3.2.0-32, switch-to-tty + restart-x
routine doesn't work even with the previously working setup. 
It exhibits the same issue as 3.7-rc5.

Any clue why so?
Something to do with VRAM registers?
Just guessing..

Thanks,
Kunal