Bug#755722: systemd must sync systemclock to RTC on shutdown

Stefan Fritsch sf at sfritsch.de
Thu Feb 12 23:09:00 GMT 2015

You really should CC the the submitter when responing.

On Tuesday 10 February 2015 09:56:28, Martin Pitt wrote:
> Control: severity -1 normal
> Stefan Fritsch [2015-01-31 10:19 +0100]:
> > severity 755722 serious
> > retitle 755722 systemd must sync systemclock to RTC on shutdown

> This is severity inflation according to
> https://www.debian.org/Bugs/Developer#severities ; adjusting back to
> original severity.

No. It breaks other software, like fsck and make. I would call make an 
unrelated package which would make severity critical appropriate.

> I also disagree with the retitling, FTR.
> > Systemd must make sure that the system clock does not go
> > backwards,
> > which causes all kinds of problems, with file systems and with
> > other software. To achieve that, systemd has to sync the system
> > time to RTC on shutdown.
> I disagree. As the discussion showed, it is in no way clear why the
> system time should be more accurate than the hardware clock; on most
> hardware it will be the other way around.

I don't deny that. But monotonic time is more important than accurate 
time. You have not commented on that in any way.

On long running systems, even if nothing modifies the system clock the 
normal drift between system time and RTC can cause the system time to 
go backwards when the system is rebooted. Therefore the system time 
must be synced to the RTC on shutdown.

> IMHO the only proper time to write the hardware clock is when we
> know the system time is correct, i. e. after an NTP sync or when
> the user sets it manually.

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