[tz] [PATCH] Introduce Epoch offset and local time Epoch

[Guy Harris]

On Oct 25, 2016, at 11:42 PM, Random832 <random832 at fastmail.com> wrote:

> On Wed, Oct 26, 2016, at 01:58, Paul Eggert wrote:
>> I don't see how that could work, as the epoch for GetSysTime is power-on,
> 
> It's *set* to 0 at power on, but all indications seem to be that the
> *intended meaning* is "seconds since 1978"

I.e., like some (older) UN*Xes, except that it's *documented* as starting as 0 at power-on, rather than "starting at 0" being the result of the current time value in the kernel being in a variable in the kernel's BSS space or something such as that.

(Even older UN*Xes set it to the last modified time of /, or something else from the file system, as soon as the root file system was mounted, as I remember, so the clock wasn't *quite* off.

Most if not all UN*Xes, these days, run on hardware with some flavor of time-of-day clock that continues counting during a reboot and may even have a battery so that it continues counting even if the power is turned off, and a value taken from that gets used as the current time value.  It's been so long since I've used such a system - did we *really* have to log in as root and type the "date" command after a reboot if we wanted the system's clock to be sufficiently close to reality?)