Comment 65 for bug 1009312

So I've been busy, but I have some more useful info. I've confirmed the bug's still in both version 3.5.0-40 (32 bit) and 3.2.0-53 (64 bit) of the Ubuntu kernel.

However, while I've been busy, I had the idea of just splicing the changes from Xiao's patch (which we found in the last bisect) into the mainline kernel before doing a reverse bisect on commits before that one. After a couple of false starts, I was able to isolate a prior patch clearly (I tested it 10 times in various boot-up situations, and it always worked). Apparently the magic patch was a merge by Linus:

99c6bcf46d2233d33e441834e958ed0bc22b190a by Linus Torvalds

I honestly have no clue why this patch would be the earlier necessary one, and my gut feeling is that it means this bug is very tangled and subtle. I'm both busy and a little out of my league to contact the kernel mailing-list directly, but while running the bisection, I came across the name Rafael J. Wysocki a couple of times. My 2nd reverse bisection actually uses a patch by him as the earliest commit because I originally zeroed in on his commit as the next critical one. It was only after testing over 6 or 7 boots that I confirmed a bad session.

Anyways, when searching for his commits in the git log, a recent one (60f75b8e97daf4a39790a20d962cb861b9220af5) jumped out since it sounded particularly relevant. It specifically handles interaction problems between PCI bridges and ACPI, then mentions graphics adapter detection as a major justification. I'm guessing you may already be in touch with him, but if not, it sounds like he might be a good person to talk to.