[Intel-gfx] [PATCH i-g-t 1/1] igt_aux: Skip hibernation attempts if hibernation is not configured

[Chris Wilson]

Quoting Petri Latvala (2017-12-21 13:18:16)
> On Thu, Dec 21, 2017 at 12:59:41PM +0000, Chris Wilson wrote:
> > Quoting Petri Latvala (2017-12-21 12:53:41)
> > > rtcwake doesn't give us meaningful ways of differentiating different
> > > reasons for hibernation failing. CI doesn't configure hibernation to
> > > work at this time, and hibernation attempts will always fail. Check
> > > for the configuration in the form of resume= appearing on the kernel
> > > command line, which is what swsusp uses to find the resume device to
> > > hibernate to.
> > 
> > resume= is not required for hibernation.
> 
> Oh bugger, I was blind. swsusp_resume_device update is right there in
> swsusp_swap_check().
> 
> swsusp_resume_block is not updated there though. That's needed to
> hibernate to swapfile.
> 
> >  
> > > Hibernation failures have dug up a couple of bugs in the past, but
> > > finding actual bugs in the swamp of "rtcwake failed with 1" results is
> > > difficult enough to overweigh that benefit.
> > 
> > The ones in CI are genuine though, does it not appear? At the start of
> > the hibernate it picks swapspace to store the image, but at the end of
> > the sequence, it can not read back from the swapspace it chose.
> 
> ... and the above is what happens in CI. Correct device is checked but
> offset is missing.
> 
> Suggestions how to proceed? Does resuming from a swapfile work
> automatically without resume_offset= on cmdline? Then it would be a
> matter of updating swsusp_resume_block in swsusp_swap_check. If not,
> check that either 1) a partition exists in /proc/swaps 2)
> resume_offset is on cmdline?

I've never used resume=/resume_offset= and hibernate (both from the
desktop and echo disk > /sys/power/state) works. Why CI doesn't work is
a mystery. Is it worth seeing if it has ever worked (without extra modules
like i915.ko loaded) on one of those machines and do a regression hunt?
-Chris