[LEAPSECS] Look Before You Leap ? The Coming Leap Second and AWS | Hacker News

Eric R. Smith ersmith at hfx.eastlink.ca
Tue May 19 17:49:23 EDT 2015

On 19/05/15 05:39 PM, Joseph M Gwinn wrote:
>> From: "Poul-Henning Kamp" <phk at phk.freebsd.dk>
>> To: Leap Second Discussion List <leapsecs at leapsecond.com>, Hal
>> Murray <hmurray at megapathdsl.net>
>> Date: 05/19/2015 02:22 PM
>> Subject: Re: [LEAPSECS] Look Before You Leap ? The Coming Leap
>> Second and AWS | Hacker News
>> Sent by: "LEAPSECS" <leapsecs-bounces at leapsecond.com>
>> --------
>> In message
>> <20150519181135.CACBE406057 at ip-64-139-1-69.sjc.megapath.net>, Hal
>> Murray writes:
>>> I think the problem is conflicting standards.  POSIX doesn't agree with
> UTC.
>> Not so much "doesn't agree" as "ignores".
> No, it's Doesn't Agree - the issue was very much debated.
> True UTC (with leap seconds) didn't cure a problem the committee cared
> about, and managed to cause problems they did care about.  In short, POSIX
> systems have to be able to work in a cave, with no access to the sky or
> knowledge of astronomy.

If POSIX time_t were actually a count of SI seconds elapsed since the
epoch, then a machine in a cave (with an accurate enough clock) could in
principle maintain correct timestamps. As it stands though, POSIX time_t
cannot be implemented without access to a UTC reference of some kind,
i.e. access to the sky.

Eric Smith

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