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- To: chrony-users@xxxxxxxxxxxxxxxxxxxx
- Subject: Re: [chrony-users] Time from gpsd via socket
- From: Miroslav Lichvar <mlichvar@xxxxxxxxxx>
- Date: Mon, 27 Jul 2020 09:10:41 +0200
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On Thu, Jul 23, 2020 at 09:31:08PM -0700, David Glover-Aoki wrote:
> After my original post I realized that actually I could answer my own question with an experiment.
>
> I disconnected the Pi from the network, stopped chrony, set the time to Jan 1 2019, and rebooted.
>
> A few seconds after rebooting, the time jumped back to the correct time, so this seems to prove (?) that it is getting both clock time, *and* PPS, from the one SOCKet.
For chrony, a PPS refclock is one that doesn't provide complete time,
just pulses relative to the closest second (or a fraction of a second
for >1Hz PPS). That can come from the /dev/pps* refclock, or the SOCK
refclock.
But with gpsd using SHM or SOCK, the sample is always complete. It's
not a PPS refclock, even though the data originally came from a PPS
device. gpsd already did the job of pairing the pulses with seconds.
Suggestions/patches for the chrony.conf man page are welcome.
--
Miroslav Lichvar
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