Re: number of seconds since the epoch

[Taylor R Campbell <campbell+netbsd%mumble.net@localhost>]

   Date: 08 Dec 2010 11:21:41 -0500
   From: Daniel Hagerty <hag%linnaean.org@localhost>

   Robert Elz <kre%munnari.OZ.AU@localhost> writes:

   > Clearly you're looking for a count of seconds including
   > leap seconds, right?   That's the magic 24 in your message.
   > That is you're not interested in the elastic seconds that
   > posix defines, for which there are always exactly 86400 in a day.

Exactly.  I'd like to do this without customizing my installation of
the operating system from source, as you (Robert Elz) suggested, much
as such a custom installation may be the right thing.  Also, it looks
like even if I do replace the zoneinfo files, time, gettimeofday, and
clock_gettime will still behave badly on a leap second, and rewind.

       If you just need now, there is a way that might border on nice.
   If you need the past, more work.

Well, a well-behaving substitute for clock_gettime, together with
posix2time, is definitely better than having only a corrupted (i.e.,
POSIX) clock.  There is a danger that the two will lose synchrony if
the nearest NTP server announces a leap second that posix2time doesn't
yet know about.  But that's less catastrophic than a self-rewinding
clock_gettime.

       NTP stratum ones are expected to carry a current copy of
   ftp://time.nist.gov/pub/leap-seconds.list
   in the ntp daemon's keysdir, plus the config line
   "crypto leap leap-seconds.list".

       Setup ntp thusly, and then...

This looks great.  However, I went through the NTP man pages and HTML
documentation in /usr/share/doc/html/ntp (which are pretty poorly
synchronized, it seems), and tried various things, and couldn't figure
out precisely what you mean by `setup ntp thusly'; in no configuration
I tried was I able to elicit a TAI offset other than 0 from ntptime or
ntp_gettime.  Can you be more specific?  I'd like just to configure
ntpd on a single host -- I don't want to set up my own NTP server.