Yo Hal! On Fri, 23 Mar 2018 17:15:51 -0700 Hal Murray via devel <devel@ntpsec.org> wrote:
> Gary said:
> > The raspberry pi has no RTC. When it starts cold, the time may
> > well be in 1969. Somehow, not sure how, that becomes 2134. Then
> > gpsd uses that as the GPS epoch, and things go downhill from
> > there...
>
> So gpsd does something stupid and you expect ntpd to figure out how
> to recover?
Yup. It is the job of ntpd to remove false chimers. And in my case,
it does so, but still sets the wrong time.
> This is a good example of the sort of heuristic I was talking about.
> If the time really is in 2134, then gpsd might be doing the right
> thing. But how likely is that?
Sadly GPS time is in weeks, modulo 1024. So 2134 just one of many
cases.
> Do we know how a Raspberry Pi sets its clock during boot?
It has no RTC, so nothing to set the clock from. There are a few
heuristics that various distros apply. None very good.
> I just rebooted a Pi with ntpd disabled. It came up with a sensible
> time. I powered it off for several minutes and it came up with the
> time when I powered it off.
Yeah, depends on your distro. They usually get it right, I'm worried
about the corner cases when it does not. Like on first boot from a
raw install.
RGDS
GARY
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