[ntp:questions] Lep seconds

David L. Mills mills at udel.edu
Fri Jan 4 14:57:00 UTC 2008


As long as you have the current NIST leapseconds file and recent NTP 
distribution, the TAI-UTC offset is provided automatically in the tai 
member of the ntp_gettime() structure. Provision for this member might 
not be universal in various operating systems. The 
/usr/include/sys/timex.h heaer file should reveal the truth.


David Woolley wrote:
> In article <298286.52982.qm at web55415.mail.re4.yahoo.com>,
> marknmbox-88 at yahoo.com wrote:
>>compliant.  Is there a similar mod for NTP.  I am
>>hoping that there is a mod that will cause NTP to
>>supply theoretical UTC (even if it is not ascci).
> Both POSIX and NTP use UTC.  Your problem is that you are not using
> using UTC, but, rather, using TAI.
> The ntpd source code is available, and it would probably be fairly easy
> to either:  produce a system dependencies module that translated UTC
> to TAI and let the OS insert the leap seconds; or to remove all the
> leap second code and convert reference clock times to TAI; however,
> the second version would be dangerous and you would need to modify the
> port number, and, if possible, make the packet formats incompatible,
> to prevent it being mistaken for a real NTP server.

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