I just opened this: http://bugzilla.kernel.org/show_bug.cgi?id=10892 . ISeems like the same bug I reported:
think itÅ a regression, but (read the description) I am not so sure, so
I checked regression but I have not blocked Rafael's metabug.
Latest working kernel version: 2.6.25
Earliest failing kernel version: After 2.6.25, exatcly don't know, probably
2.6.26-rc3
Distribution:Ubuntu 8.04 Hardy
Hardware Environment: toshiba U305 intel-based laptop, see
http://bugzilla.kernel.org/attachment.cgi?id=16067&action=view
Software Environment:xserver-xorg-video-intel 2:2.2.1-1ubuntu12, see also
http://bugzilla.kernel.org/attachment.cgi?id=16066&action=view
Problem Description:
Sometime, on cold boot (after the laptop has been shut off), when the screen
switch from the Ubuntu startup to gdm, the screen goes blank. Forever.
Rebooting (warm) with the same kernel cures it, sometime. If I reboot 2.6.25 it
cures it everytime.
Otherwise, the system seems to be working.
It was difficult to see because I almost never do a cold boot, the laptop is
either sleeping (s2ram) or on, or (warm) rebooted when I test a new kernel.
Helps / tricks to gather more data when it happens are welcome.
sched: high-res preemption tickYou could try git bisecting the bug, but you might run into problems. When I got down to the last ~80 commits the compiled kernel corrupted my real time clock! So, I'm not 100% sure the the commit that git reported was the _exact_ first bad, but fairly close (that, and the blank screen doesn't happen all the time). But if your git bisect returns the same or similar commit we might be able to narrow down the possibilities.
Use HR-timers (when available) to deliver an accurate preemption tick.