Return-Path: Received: by vger.rutgers.edu id <154443-8316>; Sat, 12 Sep 1998 13:14:55 -0400 Received: from mail.his.com ([205.177.25.9]:2835 "EHLO mail.his.com" ident: "root") by vger.rutgers.edu with ESMTP id <154591-8316>; Sat, 12 Sep 1998 13:02:33 -0400 Message-ID: <35FAD20D.DBA99899@his.com> Date: Sat, 12 Sep 1998 15:57:01 -0400 From: Feuer Reply-To: feuer@his.com X-Mailer: Mozilla 4.06 [en] (Win95; U) MIME-Version: 1.0 To: Linux Kernel Subject: Re: GPS Leap Second Scheduled! References: <19980909200032.B13292@caffeine.ix.net.nz> <199809092149.RAA06993@hilfy.ece.cmu.edu> <6t7ag1$trf$1@palladium.transmeta.com> Content-Type: text/plain; charset=x-user-defined Content-Transfer-Encoding: 8bit Sender: owner-linux-kernel@vger.rutgers.edu Content-Length: 3000 Lines: 83 ? H. Peter Anvin wrote: > Followup to:? <199809092149.RAA06993@hilfy.ece.cmu.edu> > By author:??? "Brandon S. Allbery KF8NH" > In newsgroup: linux.dev.kernel > > > > In message <19980909200032.B13292@caffeine.ix.net.nz>, Chris Wedgwood writes: > > +----- > > | On Wed, Sep 09, 1998 at 12:59:47AM +0000, H. Peter Anvin wrote: > > | > The way xntp deals with leap seconds is it lets the epoch float... > > | > i.e. it holds time_t to the same value for two seconds. > > | Cool... so 1970 becomes even longer ago that I would have assumed > > | then? > > +--->8 > > > > That's the only semi-reasonable (I stress *semi-*) interpretation one can > > give to the current standard.? The other possibilities are worse. > > > > Right.? I think the right solution is one I suggested on c.o.l.d.s > recently: > > - time_t being a 64-bit signed integer linked to UTC > - struct timespec (and struct timeval, presumably) having an extra > ? field added: > > ??????? 64-bit seconds field (same as time_t) linked to UTC > ??????? 32-bit nanosecond field (microsecond for timeval) linked to TAI > ??????? 32-bit integral TAI-UTC difference > > That way any moment in time will be uniquely derivable at least, at a > positive leap second, you will see the progression (where T means a > time_t value divisible by 86400): > ? Why would you have the TAI-UTC difference instead of just TAI? The part of your message below was very confusing to me. ? ? > ? > ??????? tv_sec????????? tv_delta??????? UTC > > ??????? T-3???????????? N?????????????? 23:59:57 > ??????? T-2???????????? N?????????????? 23:59:58 > ??????? T-1???????????? N?????????????? 23:59:59 > ??????? T-1???????????? N+1???????????? 23:59:60 > ??????? T?????????????? N+1???????????? 00:00:00 > ??????? T+1???????????? N+1???????????? 00:00:01 > ??????? T+2???????????? N+1???????????? 00:00:02 > > ... and for a negative leap second ... > > ??????? tv_sec????????? tv_delta > > ??????? T-3???????????? N?????????????? 23:59:57 > ??????? T-2???????????? N?????????????? 23:59:58 > ??????? T?????????????? N-1???????????? 00:00:00 > ??????? T+1???????????? N-1???????????? 00:00:01 > ??????? T+2???????????? N-1???????????? 00:00:02 > > We may want to have a testable bit that we're "in" a leap second for > the 23:59:60 case... > > ??????? -hpa > > -- > ??? PGP: 2047/2A960705 BA 03 D3 2C 14 A8 A8 BD? 1E DF FE 69 EE 35 BD 74 > ??? See http://www.zytor.com/~hpa/ for web page and full PGP public key > ??????? I am Bah?'? -- ask me about it or see http://www.bahai.org/ > ?? "To love another person is to see the face of God." -- Les Mis?rables > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.rutgers.edu > Please read the FAQ at http://www.tux.org/lkml/faq.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/faq.html