General information on Leap Second 2016

This document (7017873) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 12 Service Pack 1 (SLES 12 SP1)
SUSE Linux Enterprise Server 12 GA LTSS (SLES 12 LTSS)

SUSE Linux Enterprise Server 11 Service Pack 4 (SLES 11 SP4)
SUSE Linux Enterprise Server 11 Service Pack 3 LTSS (SLES 11 SP3 LTSS)
SUSE Linux Enterprise Server 11 Service Pack 2 LTSS (SLES 11 SP2 LTSS)

SUSE Linux Enterprise Server 10 Service Pack 4 LTSS (SLES 10 SP4 LTSS)

Situation

IERS (International Earth Rotation and Reference Systems Service) announced a leap second for 31st of December 2016 as per: https://datacenter.iers.org/web/guest/eop/-/somos/5Rgv/latest/16

A positive leap second will be introduced at the end of December 2016.
The sequence of dates of the UTC second markers will be:

                          2016 December 31, 23h 59m 59s
                          2016 December 31, 23h 59m 60s
                          2017 January   1, 0h 0m 0s

The difference between UTC and the International Atomic Time TAI is:

from 2015 July 1, 0h UTC, to 2017 January 1 0h UTC   : UTC-TAI = - 36s
from 2017 January 1, 0h UTC, until further notice    : UTC-TAI = - 37s

Resolution

SUSE is not aware of any new kernel bugs for the upcoming leap second, so the information from TID#7016150 still apply.

Please review TID#7016150 for further details.

Bug#988184 - timezone: 2016 leap second update

SUSE has released the updated timezone package and it is available for all maintained products as well as for active LTSS subscriptions.
The timezone package merely records the fact that there will be a leap second. Inserting it into the kernel can happen via various ways, including from external via ntpd.
ntpd is capable of receiving the leap second announcement from its reference clocks. The reference clock may be one or more of the following:
Organization or internet time servers, via ntp protocol (the standard configuration)
GPS receiver (announced in protocol some months in advance)
a radio clock receiver e.g. DCF77 (announced in protocol at beginning of hour)
directly attached atomic clock (unlikely)
The leap second announcement will be distributed down in the internal network via the ntp protocol. The leap second will be inserted into the kernel on all machines running ntpd, unless they are configured for slew mode (-x -g)

Kernel testing

SLE kernels are tested against regressions in kernel timer code when inserting positive leap seconds, which previously caused issues. The relevant tests are contained in these 2012 commits to the kernel test suite here.
This kernel test suite is applied when releasing SLE products or maintenance updates. This covers the following products incl. LTSS and their history of released kernels, from the versions described in TID#7016150.

SLE 12 GA LTSS
SLES 12 SP1 and up
SLES 11 SP3 LTSS
SLES 11 SP4

Cause

Additional Information

SUSE will update this document accordingly if any additional information becomes available.

Disclaimer

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