[LEAPSECS] Time math libraries, UTC to TAI

[Warner Losh]

On Wed, Dec 28, 2016 at 12:59 PM, Steve Summit <scs+ls at eskimo.com> wrote:
> Warner Losh wrote:
>> ...There's other systems that 'freeze' time during the leap second,
>> only incrementing it by a tiny fraction for each gettimeofday call.
>
> Do you know which systems those are?  I haven't found any of them.
> I know Dave Mills talks about them.  I've heard that Linux implemented
> that scheme once, but later removed it.

Some versions of Linux. Some versions of Ultrix / OSF on Alpha did
similar. There are several NTP hardware servers that did likewise
internally. I also think OS/MP on Solbourne computers did this, but
can't easily check anymore. OS/MP was based on SunOS 4.x, and I think
it inherited it from there. I haven't checked lately to know who may
still be doing it. There are some systems that really want to have
consistent, monotonically increasing time no matter what, and will
accept time being wrong in rare cares to achieve that.

Warner