Messages in this thread | | | Date | Mon, 12 Jan 2009 10:07:12 -0700 (MST) | Subject | Re: [ntpwg] Bug: Status/Summary of slashdot leap-second crash on new years 2008-2009 | From | "M. Warner Losh" <> |
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In message: <20090112161115.GA1474@ucw.cz> Pavel Machek <pavel@suse.cz> writes: : 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.
Well, today you can ftp the leapseconds.txt file from NIST. Of course, that assumes your machine is on the network, and not a dumb slave of a smart head-end that's off the net...
Warner
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