Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755229AbZAEOdv (ORCPT ); Mon, 5 Jan 2009 09:33:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754419AbZAEOdn (ORCPT ); Mon, 5 Jan 2009 09:33:43 -0500 Received: from vps1.tull.net ([66.180.172.116]:40784 "HELO vps1.tull.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754046AbZAEOdm (ORCPT ); Mon, 5 Jan 2009 09:33:42 -0500 Date: Tue, 6 Jan 2009 01:33:35 +1100 From: Nick Andrew To: Linas Vepstas Cc: David Newall , david@lang.hm, Kyle Moffett , Ben Goodger , Robert Hancock , linux-kernel@vger.kernel.org, "Jeffrey J. Kosowsky" , MentalMooMan , Travis Crump , burdell@iruntheinter.net Subject: Re: Bug: Status/Summary of slashdot leap-second crash on new years 2008-2009 Message-ID: <20090105143335.GC18055@mail.local.tull.net> References: <495F0672.6020708@davidnewall.com> <8752a8760901022237r75d408b3i74c703c8ac2d4597@mail.gmail.com> <496076A9.7030907@davidnewall.com> <4960897D.5030603@davidnewall.com> <4961432A.80509@davidnewall.com> <49614835.7000505@davidnewall.com> <3ae3aa420901042148o1c96985dube8e03085c997a07@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3ae3aa420901042148o1c96985dube8e03085c997a07@mail.gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-SMTPD: qpsmtpd/0.26, http://develooper.com/code/qpsmtpd/ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1499 Lines: 32 On Sun, Jan 04, 2009 at 11:48:31PM -0600, Linas Vepstas wrote: > There *was* talk of eliminating them forever (so as to > avoid this kind of bug, which affects banks, satellites, > telecom equipment, etc.) but I guess they didn't do it. I can sympathise with the opinion that linux should be able to accurately distinguish xx:59:60 when a leap second is added (or the missing :59 when one is subtracted) but not at the expense of making a day which is not 86400 seconds long. To fix the problem would require accurately modeling international timekeeping standards such as TAI and use of different syscalls to return time in TAI and UTC-with-leap-seconds represented. It wouldn't be good to change the semantics of time(). * http://en.wikipedia.org/wiki/International_Atomic_Time * http://en.wikipedia.org/wiki/Leap_second 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, using control files which are updated as leap seconds are declared. Just so long as the existing behaviour of time() which doesn't recognise leap seconds is preserved. Nick. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/