x86 Suspend/resume support in Hoary

[Sami Haahtinen]

Matthew Garrett wrote:
> Suspend and resume support has now landed in Hoary. Please see
> http://www.ubuntulinux.org/wiki/HoaryPM for instructions on how to set
> it up and test it, and then add your results to
> http://www.ubuntulinux.org/wiki/HoaryPMResults . The amount of feedback
> we get will determine how things are set up by default in Hoary, so
> please let us know how well stuff works.

I don't think i'll report these results to PMResults. Although, i'll be 
adding other status info there shortly.

I ran into an odd problem with hibernate (well not really that odd, but 
unexpected) The second time i tried to suspend, hibernate failed for 
some reason and the laptop returned back to a working state. Ok, this is 
nothing odd, we are still doing experimental trickery. I decided to find 
out the cause the next day, shut down the computer and went to bed. This 
morning i booted up the computer and to my surprise, the computer 
resumed with the state from the crashed hibernate. This wasn't really a 
surprise as i don't run memory intense apps so my computer doesn't swap 
a lot and it didn't overwrite the hibernate info in swap.

This will become a problem when you think it through. The resumed memory 
contains an image of my filesystem allocation table, which has changed 
when i shut down the computer. Thus i ended up with a corrupted XFS 
filesystem. Fixing this isn't really a problem, but resuming made the 
boot fail and the kernel crash, and since swap still contained the 
resume image after rebooting we were right back where we started.

It was rather simple to work around it by rebooting with a liveCD and 
fix the filesystem and then boot up with resume disabled. For an end 
user it's not that simple. Some precautions should be taken to avoid 
these kinds of problems.

  -- Sami