From 5447c0509f5160db72065aaeac078639486aee68 Mon Sep 17 00:00:00 2001 From: Christian Breunig Date: Sun, 21 Jan 2024 20:48:33 +0100 Subject: ntp: T5692: add support to configure leap second behavior (cherry picked from commit 2443622964b476bfbcf88b05322fd27b55406fad) --- docs/configuration/service/ntp.rst | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/docs/configuration/service/ntp.rst b/docs/configuration/service/ntp.rst index 08be047c..e7ee392b 100644 --- a/docs/configuration/service/ntp.rst +++ b/docs/configuration/service/ntp.rst @@ -81,4 +81,33 @@ Configuration .. cfgcmd:: set service ntp vrf - Specify name of the :abbr:`VRF (Virtual Routing and Forwarding)` instance. + Specify name of the :abbr:`VRF (Virtual Routing and Forwarding)` instance. + +.. cfgcmd:: set service ntp leap-second [ignore|smear|system|timezone] + + Define how to handle leaf-seonds. + + * `ignore`: No correction is applied to the clock for the leap second. The + clock will be corrected later in normal operation when new measurements are + made and the estimated offset includes the one second error. + + * `smear`: When smearing a leap second, the leap status is suppressed on the + server and the served time is corrected slowly by slewing instead of + stepping. The clients do not need any special configuration as they do not + know there is any leap second and they follow the server time which + eventually brings them back to UTC. Care must be taken to ensure they use + only NTP servers which smear the leap second in exactly the same way for + synchronisation. + + * `system`: When inserting a leap second, the kernel steps the system clock + backwards by one second when the clock gets to 00:00:00 UTC. When deleting + a leap second, it steps forward by one second when the clock gets to + 23:59:59 UTC. + + * `timezone`: This directive specifies a timezone in the system timezone + database which chronyd can use to determine when will the next leap second + occur and what is the current offset between TAI and UTC. It will + periodically check if 23:59:59 and 23:59:60 are valid times in the + timezone. This normally works with the right/UTC timezone which is the + default + -- cgit v1.2.3