Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759400AbZAGRlw (ORCPT ); Wed, 7 Jan 2009 12:41:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752248AbZAGRlo (ORCPT ); Wed, 7 Jan 2009 12:41:44 -0500 Received: from bsdimp.com ([199.45.160.85]:50744 "EHLO harmony.bsdimp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752113AbZAGRln (ORCPT ); Wed, 7 Jan 2009 12:41:43 -0500 Date: Wed, 07 Jan 2009 10:39:47 -0700 (MST) Message-Id: <20090107.103947.1324582654.imp@bsdimp.com> To: mayer@ntp.isc.org Cc: linasvepstas@gmail.com, david@lang.hm, hancockr@shaw.ca, kyle@moffetthome.net, slashdot@jameshallam.info, goodgerster@gmail.com, davidn@davidnewall.com, linux-kernel@vger.kernel.org, ntpwg@lists.ntp.isc.org, pretzalz@techhouse.org, burdell@iruntheinter.net, nick@nick-andrew.net, jeff@kosowsky.org Subject: Re: [ntpwg] Bug: Status/Summary of slashdot leap-second crash on new years 2008-2009 From: "M. Warner Losh" In-Reply-To: <49642674.9080703@ntp.isc.org> References: <3ae3aa420901050942y56f0ecdei39c091a73e49c1fd@mail.gmail.com> <49642674.9080703@ntp.isc.org> X-Mailer: Mew version 5.2 on Emacs 21.3 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1072 Lines: 23 In message: <49642674.9080703@ntp.isc.org> Danny Mayer writes: : Why don't you tell us what the real problem is instead of telling us : that you need TAI offset information? The real problem is that POSIX time_t totally ignores leap seconds. This forces systems that are rolling through a leap second to repeat time, causing time to jump backwards by 1s (or violate POSIX time_t's invariant that midnight time_t is % 86400 == 0). This jump backwards is a pita in the kernel, and violates the assumption that many programs have that time doesn't flow backwards. The suggestion to solving this would be to tick in TAI time, and force userland to cope with the leapsecond issues. Of course, there's a number of problems with this solution as well, but it feels like it belongs there... Warner -- 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/