Arch Linux

android

Member

From: San Diego

Registered: 2003-04-18

Posts: 160

the new leapsecond is here! (but I can't see it) [Sort of SOLVED]

hola

As many may know a new leapsecond was recently announced (attached at bottom)

As an avid user of xdaliclock I'd like to use it to display this event at a "New Seconds Eve" party (running on ArchLinux of course).

Now the question: Will this work?

Will xdaliclock actually display 15:59:60 after 15:59:59?

That's local time here in california, where the leapsecond will be inserted just before 4pm.

I did some source reading, and mailed a couple of time knowledgeable people, try to decide if this would work.

One offered an excellent suggestion: set your clock ahead and test it.

Well Alright, it's always good to listen to advise from the dont-underestimate-the-obvious department.

So I used `date 12311558` to set the clock to 4pm PST on Dec 31st.

I watch as the seconds tick, tick, tick and right after 15:59:59 comes... 16:00:00

No leapsecond 8-(

I'm running djb's clockspeed as an SNTP client and have updated the leapsecs.dat with the new one including this year. (I even restarted clockspeed)

I made sure to `cp -p /usr/share/zoneinfo/right/America/Los_Angeles /etc/localtime` because of the crucial need for a "right" timezone for sync with TAI time.

I've done quite a bit of scroggling trying to make sense of how time info makes it's way through unix to actually be displayed in userland by something like date or xdaliclock. I didn't make sense 8-(

Can anyone help on this?

How does the TIMEZONE variable set in rc.conf find it's way into timekeeping?

Is the 2.6.25 kernel going to show a UTC 23:59:60 after 23:59:59?

XDaliClock uses the localtime() function call to fetch time from the system.

Thanks!

android

~~~~~~~~~~~~~~~~~~~~~~~~~ leap second announcement ~~~~~~~~~~~~~~~~~~~~~~~~~

     INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE (IERS)

SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE

SERVICE DE LA ROTATION TERRESTRE
OBSERVATOIRE DE PARIS
61, Av. de l'Observatoire 75014 PARIS (France)
Tel.      : 33 (0) 1 40 51 22 26
FAX       : 33 (0) 1 40 51 22 91
e-mail    : services.iers@obspm.fr
http://hpiers.obspm.fr/eop-pc

                                              Paris, 4 July 2008

                                              Bulletin C 36

                                              To authorities responsible
                          for the measurement and
                          distribution of time

                                   UTC TIME STEP
                            on the 1st of January 2009

A positive leap second will be introduced at the end of December 2008.
The sequence of dates of the UTC second markers will be:       
       
                          2008 December 31,     23h 59m 59s
                          2008 December 31,     23h 59m 60s
                          2009 January   1,      0h  0m  0s

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

  from 2006 January 1, 0h UTC, to 2009 January 1  0h UTC  : UTC-TAI = - 33s
  from 2009 January 1, 0h UTC, until further notice       : UTC-TAI = - 34s

Leap seconds can be introduced in UTC at the end of the months of December
or June, depending on the evolution of UT1-TAI. Bulletin C is mailed every
six months, either to announce a time step in UTC or to confirm that there
will be no time step at the next possible date.

                                              Daniel GAMBIS
                                              Head       
                                              Earth Orientation Center of IERS
                          Observatoire de Paris, France

Last edited by android (2008-09-12 21:30:54)

android

Member

From: San Diego

Registered: 2003-04-18

Posts: 160

Re: the new leapsecond is here! (but I can't see it) [Sort of SOLVED]

I can't beleive I never closed this post!

I also started an unfinished Wiki entry on Time in general, leading to time reepresentation in linux and then on to the leapsecond:

http://wiki.archlinux.org/index.php/Time

The leapsecond issue was solved by downloading the tzdata source and editing the file "leapsecond".

Then the zoneinfo files are rebuilt with the zic -L leapsecond command.

There is also a tzcode tarball that contains the programs.

In Arch Linux, as in most GNU/Linux distributions, the compiled time zoneinfo files and the programs are rolled together into a tzdata package. Basically, this package needs to be recompiled to support new leapsecond announcements.

From the tzcode README:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Here is a recipe for acquiring, building, installing, and testing the
tz distribution on a GNU/Linux or similar host.

        mkdir tz
        cd tz
        wget 'ftp://elsie.nci.nih.gov/pub/tz*.tar.gz'
        gzip -dc tzcode*.tar.gz | tar -xf -
        gzip -dc tzdata*.tar.gz | tar -xf -
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

So that wraps up the forum post, now to finish that wiki entry,
maybe I just need to add a couple of leaphours to today 8-)...

android

edit: p.s. Here's an animated gif of how XDaliClock will look on the big day (at least here in pacific time):               http://johnea.net/leap-xdaliclock.gif

Last edited by android (2008-09-12 21:36:50)