Re: gpsd + chrony + pps

[Dan Williams]

Because this works:

> refclock SOCK /var/run/chrony.pps0.sock refid PPS2 lock GNSS

> refclock PPS /dev/pps0 refid PPS3 lock GNSS

But this doesn't:

> For the socket method, i can't use chrony.tty***.sock it doesn't work

I think what's happened is that the /var/run/chrony.*.sock will correspond to one of two different types of pps source :

1. If you're getting a pps source via /dev/pps0, and your .sock corresponds to that, that makes sense.

2. If you're getting a pps source from /dev/ttyS*, then I would expect a /var/run/chrony.*.sock entry corresponding to the tty port.

Trying to read from the .sock entry corresponding to the inactive PPS , well that makes sense that it would break.

Personally, I think the documentation (charitably speaking) glosses over this as an "obvious" thing to change;  what information would make that section clearer / easier to understand?

Daniel Williams  |  Software Engineer

dwilliams@nextdroid.com

On Thu, Jun 18, 2020 at 3:07 PM Stéphane Péneau <stephane.peneau@wanadoo.fr> wrote:

Hi Gary!

I don't really have a problem as I can get pps in chrony with at least 3 methods, kpps, shm, socket :

Let's start with coarse time :

refclock SHM 0 refid GNSS offset 0.2 delay 0.2 noselect

Then i can add any of these 3 lines to add PPS, and it will work:

refclock SHM 1 lock GNSS refid PPS precision 1e-9

refclock SOCK /var/run/chrony.pps0.sock refid PPS2 lock GNSS

refclock PPS /dev/pps0 refid PPS3 lock GNSS

For the socket method, i can't use chrony.tty***.sock it doesn't work

But it is what it is indicated in the chrony documentation

https://chrony.tuxfamily.org/doc/3.5/chrony.conf.html

Or in the gpsd documentation :

https://gpsd.gitlab.io/gpsd/gpsd-time-service-howto.html#_feeding_chrony_from_gpsd

So my question is :

Is there a misunderstanding on my side, or is there a mistake in the documentation?

Stéphane