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On Mon 2009-01-05 11:42:35, Linas Vepstas wrote: > 2009/1/5 <david@lang.hm>: > > On Mon, 5 Jan 2009, Linas Vepstas wrote: > > > >>> Arguably the kernel's responsibility should be to keep track of the > >>> most fundamental representation of time possible for a machine (that's > >>> probably TAI) and it is a userspace responsibility to map from that > >>> value to other time standards including UTC, > >> > >> Yes, this really does seem like the right solution. > >> > >>> using control files > >>> which are updated as leap seconds are declared. > >> > >> Lets be clear on what "control files" means. This does > >> *NOT* mean some config file shipped by some distro > >> for some package. That would be a horrid solution. > >> People don't install updates, patches, etc. Distros > >> ship them late, or never, if the distro is old enough. > >> > >> A more appropriate solution would be to have > >> either the kernel or ntpd track the leap seconds > >> automatically. First, the ntp protocol already provides > >> the needed notification of a leap second to anyone > >> who cares about it (i.e. there is no point in getting a > >> Linux distro involved in this -- a distribution mechanism > >> already exists, and works *better* than having a distro > >> do it). > > > > I disagree with this. NTP will only know about leap seconds if it was > > running and connected to a server that advertised the leap seconds during > > that month. > > > > for example, if you installed a new server today, how would it ever know > > that there was a leap second a couple of days ago? > > OK, good point. Unless your distro was less > than a few days old (unlikely), you are faced with the > same problem. Sure, eventually, the distro will publish > an update (which will add to the existing list of 36 leap > seconds -- which is needed in any case, since no one > has a server that's been up since 1958), but this is > unlikely to happen during this install window. > > The long term solution would be write an RFC to extend > NTP to also provide TAI information -- e.g. to add a > message that indicates the current leap-second offset > between UTC and TAI. Offset is not enough; you'd have to provide list of all previous leap seconds with 'when it happened' timestamps. -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html | ||||||||||||
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