[systemd-devel] CAD often useless

[Andrei Borzenkov]

В Wed, 15 Apr 2015 18:29:51 -0400
Felix Miata <mrmazda at earthlink.net> пишет:

> Felix Miata composed on 2015-04-15 14:48 (UTC-0400):
> 
> > Zbigniew Jędrzejewski-Szmek composed on 2015-04-15 18:11 (UTC):
> > 
> >> On Wed, Apr 15, 2015 at 13:31:38 -0400, Felix Miata wrote:
> > 
> >>> This isn't the first time or the only system. This particular one is an old
> >>> Athlon booted to F22 just updated last night. In order to try some follow-up
> >>> on a bug, I booted with drm.debug=14 log_buf_len=16M on cmdline. Somehow
> >>> after exiting IceWM back into KDM, the system quit responding. After some
> >>> waiting, I was switched to a tty full of systemd-journal failed to write
> >>> readonly filesystem messages. How the system got / into a readonly state I
> >>> have no idea, but my complaint is $SUBJECT, the time it takes, or the
> >>> complete failure, trying to reboot when there is a problem, often seeing
> >>> failed to store sound card state or failing boot *start* jobs. Why has
> >>> rebooting to get out of trouble gotten to be so nearly impossible?
> 
> >> Did you try to press CAD more than 7 times within 2s? This should
> >> result in immedate reboot.
> 
> > My fingers and keyboards are old. I just hold CAD down until reboot proceeds,
> > or not. All that have repeat and delay configurable in BIOS are set to 20 cps
> > & 250 delay. KDE I always set to same.
> 

How long? systemd will enable watchdog on shutdown/reboot which fires
off in 10 minutes by default I think.

> Needing again to CAD on yet another machine (kt88b this time, kt400 earlier),
> again encountering / going into RO state, I noticed this time the message
> "Ctrl-Alt-Del was pressed more than 7 times within 2s, rebooting
> immediately". I remember having seen this on previous occasions to need CAD,
> but it's still on the screen now, several minutes later, with the NUM key's
> LED remaining responsive. IOW, it doesn't do either what it says, or what I
> wanted. This is on F22 with PAE kernel 4.0.0-1 and PATA storage only except
> for empty floppy drive.

This will exit systemd manager loop and proceed with final killing and
unmount loop. So it is not really immediate emergency reboot. You could
try to enable debug and console output before doing it next time
(/bin/kill -RTMIN+22 1 ; /bin/kill -RTMIN+27 1), it may help to
understand where it is stuck..