Resume still broken on Thinkpad X1 Carbon

[Jonathan Corbet]

Just FYI, I tried out the F21 beta image in the vain hope that my resume
problems would have magically gone away.  No such luck.  In case anybody
is interested, here is what (little) I know...

 - Resume works great under F20.

 - Under F21, suspend seems to work fine, but there is no response to the
   power button (or any other input).  One has to hold the power button
   until the firmware gets fed up and powers things down hard.

 - The kernel doesn't seem to matter; running an F20 kernel with F21 user
   space still fails.

 - Booting with init=/bin/bash produces a system that will not resume
   under either release; it fails in pretty much the same way.
   Single-user mode, instead, resumes properly under F20.  So some sort
   of setup is happening that enables proper resume, but only on F20.

 - Running the F21 udev configuration on an F20 system still resumes
   properly.

 - As far as I can tell, the configuration of wakeup events, as found in
   sysfs, is the same on both systems.

I'm pretty well mystified, but, given my general lack of skills in this
part of the system, that's not surprising.  My next step, perhaps, is to
start disabling boot-time unit files until I find the one that makes
resume work, then try to see what's different under F21.  But if anybody
has a better idea, I'm all ears.

Thanks,

jon