On Sat, 16.07.16 17:22, Christian Hofstaedtler (c...@zeha.at) wrote: > Hi, > > I'm trying to understand how sigpwr.target is intended to be used, > but couldn't find a good explanation. systemd.special says this > target is invoked in a power fail situation, but what should happen > then? > > Debian, Ubuntu and PLD install "sigpwr-container-shutdown.service", > which for ConditionVirtualization=container runs systemctl > --no-block poweroff, i.e. triggers a shutdown for containers. For > "normal" hardware, nothing appears to be triggered. > > I could not find any services installed by Fedora or openSuSE, but > maybe I was looking in the wrong places. > > I'm now somewhat assuming there should be a default "policy" service > that causes sigpwr.target to initiate a shutdown? > > Pointers/hints on what is expected behaviour from sigpwr.target > would be highly appreciated.
My recommendatin: don't bother with SIGPWR. Traditionally on UNIX UPS software sends SIGPWR to PID 1 to initiate some special kind of shutdown operation. But it's very vaguely defined only, and one wonders why a normal shutdown isn't enough here, and why to bounce this off PID 1 with a special UNIX signal even... I am pretty sure that power management software that runs in userspace really shouldn't make use of this anymore. It should just request a normal shutdown. The only reason why one would want to bother with SIGPWR at all is that some really power-related old kernel drivers send SIGPWR to PID 1 too. From the systemd PoV: this stuff is ugly legacy crap that only exists for historic reasons and was never really well-defined in its behavour. It mostly appears to be a concept that exists only because Linux never had a useful IPC that was accessible from both kernelspace and userspace in a sane way... In systemd, we don't want anything to do with it, but some legacy folks really think it's superduper important. Hence we simply map it to a target unit, and enable users to map it to whatever they want to map it, but don't do anything smart about it at all on our own. I think it would be best of people would just forget about it... Lennart -- Lennart Poettering, Red Hat _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/systemd-devel