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From: pavel@ucw.cz (Pavel Machek)
To: linux-arm-kernel@lists.infradead.org
Subject: [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>

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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  parent reply	other threads:[~2017-06-21  7:51 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20170620213507.urobmtg34vzubrdq@piout.net>
2017-06-20 22:00 ` [PATCH 00/51] rtc: stop using rtc deprecated functions 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
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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