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

From: Pavel Machek
Date: Wed Jun 21 2017 - 03:52:07 EST


> > 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.

(cesky, pictures)

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