[ntp:questions] Leap second indication (Linux NTPD specifically)

unruh unruh at invalid.ca
Tue Mar 6 16:47:47 UTC 2012


On 2012-03-06, Phil Fisher <Phil.Fisher at ipaccess.com> wrote:
> Hi folks
> I have spent some time recently looking through the results of various G***le searches relating to LI and Leap Second and other related matters and cannot find an answer to the below.
> I would appreciate help since we need to cover the scenario where our 2.6.9 Linux kernel may crash/hang when a leap Second insert occurs (due to the printk bug).
>
> Some context to avoid repetitive simple answers along lines of upgrade XYZ:
> * we cannot move to the later 2.6.29 kernel for commercial reasons
> * we have an old NTP implementation: ntpd: ntpd 4.2.0a at 1.1190-r Mon Oct 11 09:10:20 EDT 2004 (1)
> and again we cannot upgrade this -- certainly in the timeframe prior to June 2012.
>
> In view of the above, my question(s) are:
>
> + is there a way to disable the kernel from implementing the leap second from a prior announcement? (I.e. during June the NTPD receives a LI notification and tells kernel -- my reading of various posts and RFC/protocol suggests that this can occur anytime in June and specifically in the 24 hours prior to leap second implementation)

Look at adjtimex. Or hack the ntpd source to remove the leap second
notification.


> + will stopping NTPD temporarily for a few days around the end of June avoid having the leap second implemented? (Re-enabling NTPD post the 30 June should re-synchronise time after some interval, correct?)

Sure.

> These two questions are related to a potential strategy for covering the leap second hiatus.
>
> Thanks
>
> --
> Phil Fisher| BSC Platform Engineer (Linux)
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