From: Pavel Machek <pavel@ucw.cz>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>,
Russell King - ARM Linux <linux@armlinux.org.uk>,
Benjamin Gaignard <benjamin.gaignard@linaro.org>,
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Subject: Re: [PATCH 00/51] rtc: stop using rtc deprecated functions
Date: Wed, 21 Jun 2017 09:51:52 +0200 [thread overview]
Message-ID: <20170621075152.GA15996@amd> (raw)
In-Reply-To: <alpine.DEB.2.20.1706202343120.2157@nanos>
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Hi!
> > I agree with that but not the android guys. They seem to mandate an RTC
> > that can store time from 01/01/1970. I don't know much more than that
> > because they never cared to explain why that was actually necessary
> > (apart from a laconic "this will result in a bad user experience")
> >
> > I think tglx had a plan for offsetting the time at some point so 32-bit
> > platform can pass 2038 properly.
>
> Yes, but there are still quite some issues to solve there:
>
> 1) How do you tell the system that it should apply the offset in the
> first place, i.e at boot time before NTP or any other mechanism can
> correct it?
I'd not do offset. Instead, I'd select a threshold (perhaps year of
release of given kernel?) and
if (rtc_time < year_of_release_of_kernel)
rtc_time += 0x100000000;
Ok, we'll have to move away from "rtc_time == 0 indicates zero", as
seen in some drivers.
> 2) Deal with creative vendors who have their own idea about the 'start
> of the epoch'
If someone uses different threshold, well, there will be
confusion. But only for users that have their rtc set to the past,
which is quite unusual.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2017-06-21 7:52 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-20 21:35 [PATCH 00/51] rtc: stop using rtc deprecated functions Alexandre Belloni
2017-06-20 22:00 ` Thomas Gleixner
2017-06-20 22:38 ` Russell King - ARM Linux
2017-06-21 7:51 ` Pavel Machek [this message]
2017-06-21 8:39 ` Alexandre Belloni
2017-06-21 6:34 ` Pavel Machek
2017-06-21 12:35 ` Alexandre Belloni
2017-06-21 18:08 ` Pavel Machek
2017-06-21 9:19 ` Russell King - ARM Linux
2017-06-21 9:41 ` Alexandre Belloni
-- strict thread matches above, loose matches on Subject: below --
2017-06-20 9:35 Benjamin Gaignard
2017-06-20 10:03 ` Alexandre Belloni
2017-06-20 10:07 ` Alexandre Belloni
2017-06-20 12:10 ` Pavel Machek
2017-06-20 12:24 ` Alexandre Belloni
2017-06-20 13:26 ` Pavel Machek
2017-06-20 13:37 ` Steve Twiss
2017-06-20 13:44 ` Pavel Machek
2017-06-20 13:48 ` Alexandre Belloni
2017-06-20 15:07 ` Benjamin Gaignard
2017-06-20 21:15 ` Russell King - ARM Linux
2017-06-21 9:26 ` David Laight
2017-06-21 9:35 ` Russell King - ARM Linux
2017-06-20 22:08 ` Pavel Machek
2017-06-21 9:14 ` Benjamin Gaignard
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