[systemd-devel] use RTC date/time to set system date time

[Lennart Poettering]

On Mo, 01.03.21 17:09, Michał Zegan (webczat_200 at poczta.onet.pl) wrote:

> >> There are problems with log timestamps when you do that, and it is
> >> probably why it was not done.
> >> I am wondering if the only correct way isn't to do it in initramfs (if
> >> it's systemd) before starting the journald, so that first saved logs
> >> have correct timestamps?
> >
> > The earlier you have a "correct" clock the better.
> >
> > But I mean, journald won't lie to you: the log messages are associated
> > with the timestamps that were accurate at the moment they are
> > generated. But of course, if your clock sucks then they'll look
> > differently than you might expect.
> However the initial log entries in journald are taken from dmesg and
> dmesg timestamps are relative, so setting the clock before journald
> first starts should make journal times correct.
> Or I am wrong?

kmsg comes with monotonic timestamps only. journald stores that away
but generally uses its own acquired timestamps, since it needs to
guarantee monotonicity and things.

But do note that journald typically runs in the initrd already.

Lennart

--
Lennart Poettering, Berlin