[systemd-devel] Calendar Timers: setting system clock may trigger jobs from the past

[Peter Mattern]

Hello.

If a *.timer unit's timestamp as stated by OnCalendar is in the past and 
the actual system time is even before that timestamp the *.timer gets 
activated when the system clock gets set.

This frequently happens on embedded devices which get their system time 
set during boot by 'ntpd -qg' and the like due to lack of an RTC. An 
import drawback is that *.timer units cannot be used to shut down or 
reboot the system in a context like this, imho.
Seen like so with 215 on Arch Linux, both x86 and ARM. The behaviour can 
btw. not be reproduced with cronie's or Busybox's cron implementation.

I don't know whether something could or should be done about this 
(personally I think yes), but thought it might make some sense to report 
here.

Regards,

Peter Mattern