Thread (10 messages) 10 messages, 4 authors, 2017-06-21

Re: [PATCH 00/51] rtc: stop using rtc deprecated functions

From: Pavel Machek <hidden>
Date: 2017-06-21 07:52:03
Also in: linux-arm-kernel, linux-pm, linux-rtc, linux-tegra, lkml

Hi!
quoted
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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