Re: [chrony-users] PHC / NIC / PPS mismatch

This works on the 4 NIC board:

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refclock PHC /dev/ptp3:extpps,pin=0 refid PPS width 100e-3 precision 1e-9 poll 0 lock NMEA trust

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but without ",pin=0", it does not.

On nearly identical hardware, difference being 3 NICs ( PPS wired to the 'last' NIC in both cases), this works fine:

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refclock PHC /dev/ptp2:extpps refid PPS width 100e-3 precision 1e-9 poll 0 lock NMEA trust

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Same kernel (4.19.0-18-amd64 #1 SMP Debian 4.19.208-1). Same chrony (3.4-4+deb10u1).

I'll roll the kernel forward and chrony forward from Debian 10 to Debian 11 and report results.

-- Christopher.

On Mon, Nov 15, 2021 at 12:54 AM Miroslav Lichvar <mlichvar@xxxxxxxxxx> wrote:

On Fri, Nov 12, 2021 at 05:28:56PM -0800, Christopher Hoover wrote:
> refclock SHM 0 refid NMEA precision 1e-3 poll 3 offset 100e-3 noselect
> refclock PHC /dev/ptp2:extpps refid PPS width 100e-3 precision 1e-9 lock
> NMEA poll 0 trust

> If I look for PPS, I find it on ptp0/pps0 with Bullseye.

> It is not found anywhere else.
>
> If tried telling chrony to /dev/ptp0 instead of /dev/ptp2, but it does NOT
> find the PPS.

Does the SHM refclock work correctly? If it didn't, the PPS PHC
wouldn't report any samples. You could try removing the lock option
and add an NTP server to be sure.

I don't remember any changes between chrony-3.4 and 4.0 that could
have an impact in this configuration.

You could try adding ":pin=1" to the PHC refclock config, to see if
the newer kernel is numbering the pins differently, but I doubt it.

If that doesn't help, run chronyd in strace for few seconds and post
the output here.

--
Miroslav Lichvar

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