linux-kernel - Re: Bug: Status/Summary of slashdot leap-second crash on new years 2008-2009

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Message-ID: <4962BB13.7060304@davidnewall.com>
Date:	Tue, 06 Jan 2009 12:29:47 +1030
From:	David Newall <davidn@...idnewall.com>
To:	Nick Andrew <nick@...k-andrew.net>
CC:	Linas Vepstas <linasvepstas@...il.com>, david@...g.hm,
	Kyle Moffett <kyle@...fetthome.net>,
	Ben Goodger <goodgerster@...il.com>,
	Robert Hancock <hancockr@...w.ca>,
	linux-kernel@...r.kernel.org,
	"Jeffrey J. Kosowsky" <jeff@...owsky.org>,
	MentalMooMan <slashdot@...eshallam.info>,
	Travis Crump <pretzalz@...hhouse.org>, burdell@...ntheinter.net
Subject: Re: Bug: Status/Summary of slashdot leap-second crash on new years
 2008-2009

Nick Andrew wrote:
> 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.
>   

Some days are not 86400 seconds long.  That's a fact and regardless of
how inconvenient it is, we have to live with it.  Some years don't have
365 days; some months don't have 30 days; some Februaries don' have 28
days; and now, some days don't have 86400 seconds. What's the point in
fighting this?

If you want to know the days between two times, dividing by 86400
doesn't cut it.


> 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.

We have this already; zoneinfo

> Just so long as the
> existing behaviour of time() which doesn't recognise leap seconds
> is preserved.

I haven't been able to find this Annex B that Alan talked of, so I can
only go by the man page, which states, simply and explicitly, that
time() returns seconds since Epoch, and also that Epoch is start of
January 1 1970.  To my mind, time *does* recognise leap seconds.
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