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Date: Fri, 06 Dec 2013 10:48:23 +0000
From: Laurent Bercot <ska-dietlibc@...rnet.org>
To: musl@...ts.openwall.com
Subject: Re: [PATCHv2] Add support for leap seconds in zoneinfo files
> - musl should not have configuration options that change
> the behaviour of an api (otherwise maintaining the code
> becomes much harder) so making leapseconds a libc build
> time config option does not work
Also, that would break musl's policy of "compile once, run
everywhere". Leap second usage should be a system-wide setting,
not a binary-wide setting.
> - hardcoding leapsecond tables into libc does not work either
> requires recompilations and restarts
Of course. Leap second tables should be read either from the
timezone files, as glibc does, or from a separate file.
> - if the clock source is a kernel level setting then the
> information should come from the kernel (eg in the aux
> vector or /proc)
> - if the clock source setting is an external setting (eg the
> configured time server uses GPS or TAI time scale) then the
> admin should provide the information through the filesystem,
musl shouldn't try to autodetect settings from the kernel. The
admin should be the authoritative source of information.
> but an update is still an operational hazard, and we need
> to invent a file format and provide tools to get it from the
> distributed tzdata files
That's the easy part. I'm already doing that for skalibs. I'm
willing to provide the format and the tools.
> - during the life-time of a process adding leapseconds may
> cause problems so the data should be cached at startup or
> on demand at the first gmtime call, but then there might be
> problems across processes if they don't have the same cached
> leapsecond list
Again, leap second announcements are a rare event and there's
plenty of time for admins to restart their processes. I don't
think that's something musl should care about.
--
Laurent
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