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From: Paul Eggert <eggert@cs.ucla.edu>
To: Linus Torvalds <torvalds@linux-foundation.org>,
	Arnd Bergmann <arnd@arndb.de>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	John Stultz <john.stultz@linaro.org>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Stephen Boyd <sboyd@kernel.org>,
	Florian Weimer <fweimer@redhat.com>,
	Theodore Ts'o <tytso@mit.edu>, "H. Peter Anvin" <hpa@zytor.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Alistair Francis <alistair.francis@wdc.com>,
	GNU C Library <libc-alpha@sourceware.org>,
	Karel Zak <kzak@redhat.com>,
	Lennart Poettering <lennart@poettering.net>,
	OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Subject: Re: New kernel interface for sys_tz and timewarp?
Date: Tue, 13 Aug 2019 10:49:03 -0700	[thread overview]
Message-ID: <ecf2742a-6cab-cc00-16ab-589fad07b8db@cs.ucla.edu> (raw)
In-Reply-To: <CAHk-=wiO2CWONDBud4nxoPgUJN1JEewFWhHa5wAqY8G5rrTXRQ@mail.gmail.com>

Linus Torvalds wrote:
> I assume/think that glibc uses (a) environment
> variables and (b) a filesystem-set default (per-user file with a
> system-wide default? I don't know what people do).
glibc relies on the TZ environment variable, with a system-wide default 
specified in /etc/localtime or suchlike (there is no per-user default). glibc 
ignores the kernel's 'struct timezone' settings for of this, as 'struct 
timezone' is obsolete/vestigial and doesn't contain enough info to do proper 
conversions anyway.

I've been thinking of adding NetBSD's localtime_rz etc. functions to glibc. 
These functions let user programs specify the time zone for each conversion 
between time_t and local time, and simplify and/or speed up applications dealing 
with many requests coming from different time zones. These functions also ignore 
'struct timezone'.

There's no need to put any of this stuff into the kernel.

  reply	other threads:[~2019-08-13 17:55 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-13  9:05 New kernel interface for sys_tz and timewarp? Arnd Bergmann
2019-08-13 17:10 ` John Stultz
2019-08-13 21:45   ` Alexandre Belloni
2019-08-13 17:30 ` Linus Torvalds
2019-08-13 17:49   ` Paul Eggert [this message]
2019-08-13 19:31     ` Florian Weimer
2019-08-13 20:04       ` Arnd Bergmann
2019-08-13 21:56   ` Alexandre Belloni
2019-08-14  0:06   ` Theodore Y. Ts'o
2019-08-14  8:31     ` Arnd Bergmann
2019-08-14  9:09       ` Lennart Poettering
2019-08-14  9:32         ` Alexandre Belloni
2019-08-14 12:15           ` Lennart Poettering
2019-08-19 11:09           ` Karel Zak
2019-08-19 13:43             ` Thomas Gleixner
2019-08-19 13:49               ` Thomas Gleixner
2019-08-20 18:45                 ` Alexandre Belloni
2019-08-20 18:47               ` Alexandre Belloni
2019-08-20 18:58             ` Alexandre Belloni
2019-08-27 16:27               ` Arnd Bergmann
2019-08-27 16:31                 ` Alexandre Belloni
2019-08-14 16:26     ` David Laight
2019-08-14 16:47       ` hpa
2019-08-15 13:22         ` Arnd Bergmann
2019-08-15 15:05           ` Theodore Y. Ts'o
2019-08-15 15:24             ` hpa

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