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

Pavel Machek
2017-06-21T07:52:03Z

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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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