From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@armlinux.org.uk (Russell King - ARM Linux) Date: Tue, 20 Jun 2017 23:38:59 +0100 Subject: [PATCH 00/51] rtc: stop using rtc deprecated functions In-Reply-To: References: <20170620213507.urobmtg34vzubrdq@piout.net> Message-ID: <20170620223859.GO4902@n2100.armlinux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Jun 21, 2017 at 12:00:30AM +0200, Thomas Gleixner wrote: > 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? > > 2) Deal with creative vendors who have their own idea about the 'start > of the epoch' > > 3) Add the information of wraparound time to the rtc device which > needs to be filled in for each device. That way the rtc_*** > accessor functions can deal with them whether they wrap in 2038 or > 2100 or whatever. > > #3 is the simplest problem of them :) Well, if there's additional non-volatile storage, you can store additional information in there, but you still need the RTC subsystem to be aware that the hardware is only 32-bit capable. You'd also still need something along the lines I detailed (redefining what dates the past 32-bit values indicate) to cope with the RTC being set backwards after the machine thinks (possibly incorrectly) that the date has jumped forwards. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.