[time-nuts] viewing the upcoming leapsecond with XDaliClock
uno at staver.se
Wed Oct 8 03:09:32 UTC 2008
I am sorry that I cannot give you any help. Instead I have a question to
How and where did you get to know about the "leapsecond.dat" file?
I ask you this question because before the previous leap second,
January 1, 2006, I had a set-up similar to yours. I did not use or know
about any "leapsecond.dat" file - that seems to be the reason why the clock
in my computer was off by about (I am not sure today) 33 seconds when I used
the ".../right/..." time zoneinfo file. As far as I remember, the clock
_did_ show seconds 58, 59, 60, 00, 01 (but was off by half a minute).
I tested this in advance, like you have done, but I could not test it
at the actual event: because of social reasons, I had to spend the time at a
New Year party :-)
I tried to get more help from our time researchers, but they simply
recommended that we turn off our Linux-based NTP servers a short time before
the leap second, and then turn them on afterwards. That way, they would get
the correct time initialisation from the Motorola Oncore GPS receiver, and
the seconds would be in 'exact' phase because they are created by 1-PPS
signals from four rubidium clocks and a cesium clock which were on
Such a solution works, of course, but I would like to have a proper
leap second handling in the kernel and the ntp protocol.
Later, I had a discussion with a specialist at a university about
paying him for an investigation of how the ntp and Linux kernel handle leap
seconds, but that work was never initialised.
There was also a discussion about the Linux kernel, ntp and leap
seconds in the Linux kernel mailing list, but as far as I remember, there
were radically diverging opinions on how these things should work together.
I have not followed the kernel mailing list since then.
----- Original Message -----
From: <time at johnea.net>
To: <time-nuts at febo.com>
Sent: Thursday, July 10, 2008 8:15 AM
Subject: [time-nuts] viewing the upcoming leapsecond with XDaliClock
> Hello to everyone,
> I'm new to the list and would like to ask about displaying the upcoming
> leap second on a linux workstation.
> I use a PC running linux 2.6.24 and the djb clockspeed daemon periodically
> synchronized with a couple of different NTP servers. I usually have a
> correct reading within ~10ms (I know, it's not atomic time 8-)
> I also use the "right/America/Los_Angeles" time zoneinfo file for correct
> synchronization with TAI, and installed the new leapsecond.dat file for
> 2008 in /etc. (and I restarted clockspeed)
> I'm on the pacific coast of the US and as such the leapsecond occurs here
> just before 4pm.
> I've used the date command to set the time of my computer to Dec 31 2008
> 15:58 PDT and watched as the hour rolled over: No LeapSecond!
> It goes from 15:59:59 to 16:00:00
> I've been using XDaliClock as the display, which uses the unix localtime()
> call to retrieve the time from the system.
> I've done quite a bit of scroogling in an attempt to determine how the
> is kept in the kernel and how it makes it's way through to userspace for
> applications like date and xdaliclock to access. I didn't determine 8-(
> Can anyone advise me as to the feasibility of using this configuration to
> display the leapsecond to a crowd of eager viewers at the end of this
> Thank you so much for your consideration of my noobish question, and for
> maintaining an active interest in something just because you like it!
> ciao bella...
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> and follow the instructions there.
More information about the time-nuts