On Fri, Jul 11, 2014 at 10:32:57AM +0400, Antony Pavlov wrote: > On Fri, 11 Jul 2014 08:10:26 +0200 > Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> wrote: > > > > I have an idea to put epoch offset (number of years into AD to which a zero year value > > > in the Hardware Clock refers) into "global.epoch" variable and add corresponding > > > Kconfig option for default epoch value. > > > > Does Linux support such a mechanism aswell? How can we make sure Linux > > uses the same epoch offset? > > Here is a quote from my hwclock(8) manpage: > > --getepoch > Print the kernel's Hardware Clock epoch value to standard output. This is the > number of years into AD to which a zero year value in the Hardware Clock refers. > For example, if you are using the convention that the year counter in your Hard‐ > ware Clock contains the number of full years since 1952, then the kernel's Hard‐ > ware Clock epoch value must be 1952. > > This epoch value is used whenever hwclock reads or sets the Hardware Clock. > > --setepoch > Set the kernel's Hardware Clock epoch value to the value specified by the > --epoch option. See the --getepoch option for details. > > I suppose that Hardware Clock epoch depends on RTC-chip. I see no automatic machanism to guarantee the same epoch > for linux and barebox. Is this used anywhere? Running a hwclock --getepoch on my desktop PC answers with: | hwclock: The kernel keeps an epoch value for the Hardware Clock only on an Alpha machine. | This copy of hwclock was built for a machine other than Alpha | (and thus is presumably not running on an Alpha now). No action taken. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
