Re: [PATCH ghak10 v5 2/2] timekeeping/ntp: Audit clock/NTP params adjustments
On Mon, 27 Aug 2018, Miroslav Lichvar wrote:
On Mon, Aug 27, 2018 at 01:35:09PM +0200, Ondrej Mosnacek wrote:
> On Fri, Aug 24, 2018 at 9:51 PM Richard Guy Briggs <rgb(a)redhat.com> wrote:
> > It appears this time_tai use of "constant" is different than
> > time_constant, the former not mentioned by Miroslav Lichvar. What is it
> > and is it important to log for security? It sounds like it is
> > important.
> The TAI offset is the offset of the clock from the International
> Atomic Time, so basically the time zone offset. I suppose it can't
> influence the audit timestamps, but changing timezones can still cause
> all sorts of confusion throughout the system, so intuitively I would
> say we should log it.
It's not related to timezones. ADJ_TAI sets the offset of the system
TAI clock (CLOCK_TAI) relative to the standard UTC clock
(CLOCK_REALTIME). CLOCK_TAI is rarely used by applications. Setting
the TAI offset effectively injects a whole-second offset to the TAI
time.
Rarely used today, but with TSN it's going to get more usage in not so
distant future.
Thanks,
tglx