Xref: utzoo unix-pc.general:2506 comp.sys.att:5902
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!bpa!cbmvax!ditto
From: ditto@cbmvax.UUCP (Michael "Ford" Ditto)
Newsgroups: unix-pc.general,comp.sys.att
Subject: Re: DST
Summary: In localtime(3C), not in the kernel
Keywords: unixpc DST rules
Message-ID: <6333@cbmvax.UUCP>
Date: 20 Mar 89 04:11:56 GMT
References: <476@dmk3b1.UUCP>
Reply-To: ditto@cbmvax.UUCP (Michael "Ford" Ditto)
Distribution: usa
Organization: Commodore Technology, West Chester, PA
Lines: 27

In article <476@dmk3b1.UUCP> dmk@dmk3b1.UUCP (David Keaton) writes:
>Does anyone know where to look in the Unix PC kernel binary to change
>the algorithm for computing Daylight Savings Time?

The kernel doesn't have anything to do with timezones or DST.  The US
DST algorithm is in localtime(3C).  It uses the old (pre-1986) rules
so it doesn't work correctly for some dates after 1986; this could be
fixed by modifying the shared library (if that were practical) but
that wouldn't fix those few programs that don't use the shlib.  Last
year, a few people posted patches that just make the localtime in the
shared library always use the post-1986 rules; the official "fix"
AT&T gave back in 1986 was to set TZ to "PDT7" instead of "PST8PDT"
(or a similar change for your timezone) on the day that DST starts,
and change it back sometime before DST ends.  Neither method really
fixes the problem.

This year, I plan to complain to AT&T very loudly since I hear they
are getting some fixdisks ready, and hopefully the DST stuff can
finally be fixed (only three years late).  I encourage everyone else
to complain as well.
-- 
					-=] Ford [=-

"The number of Unix installations	(In Real Life:  Mike Ditto)
has grown to 10, with more expected."	ford@kenobi.commodore.com
- The Unix Programmer's Manual,		...!sdcsvax!crash!kenobi!ford
  2nd Edition, June, 1972.		ditto@cbmvax.commodore.com