Hal Murray wrote: > > tvb said: >> There's no ambiguity. Those are just bugs. No software should depend on more >> than 1 month notice of a leap second and no software should be fooled if the >> notice is months or even years in advance.
Please keep in mind that e.g. GPS sends out leap second announcements about 6 months in advance. This is not a problem if the receiver firmware follows the specs, since the week number and day number are specified. But, as we have seen, this can be a problem due to bugs in the receiver firmware. > There are plenty of quirks in ntp code along that line. The APIs don't have > an explicit when. The NTP-Kernal API for leap-pending is leap-tonight. You > have most of the next day to turn it off. The leap-pending on the wire is > leap-at-the-end-of-this-month. I think this is some "best practice" that has evolved over many years. For the kernel, the "end of this day" announcement is sufficient. For the protocol, roughly 1 month is sufficient but short enough to avoid ambiguous dates, i.e. at the end of which month. If I remember correctly, the PTP specs even specify an announcement interval of 12 hours only, the German DCF77 transmitter sends the announcement only 1 hour in advance, and IRIG time codes (if they support it at all, like IEEE1344 / C37.118) only 10 seconds or so in advance. So I wonder which spec should have been relevant for NTP/ntpd? Martin -- Martin Burnicki Senior Software Engineer MEINBERG Funkuhren GmbH & Co. KG Email: [email protected] Phone: +49 5281 9309-414 Linkedin: https://www.linkedin.com/in/martinburnicki/ Lange Wand 9, 31812 Bad Pyrmont, Germany Amtsgericht Hannover 17HRA 100322 Geschäftsführer/Managing Directors: Günter Meinberg, Werner Meinberg, Andre Hartmann, Heiko Gerstung Websites: https://www.meinberg.de https://www.meinbergglobal.com Training: https://www.meinberg.academy _______________________________________________ LEAPSECS mailing list [email protected] https://pairlist6.pair.net/mailman/listinfo/leapsecs
