Re: PTP TAI Query
Chris Hodgetts <[email protected]> Tue, 25 Nov 2025 01:37:13 +1300
| Newsgroups | gmane.comp.time.chrony.user |
|---|---|
| Message-ID | <[email protected]> |
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Hello,
Just a quick follow-up in case anyone else runs into this.
I was initially seeing all zeros and a =E2=80=9C?=E2=80=9D on the PHC =
source line, which made it look like chrony wasn=E2=80=99t treating the =
PHC as a valid source, but there were no errors when iit started, or =
that I could see in any log.=20
I originally suspected a chrony issue after upgrading, but it turned out =
not to be related to chrony at all.
The actual cause was that right/UTC was no longer present in my tzdata =
after upgrading to Debian 13 (at least on my system).=20
Without that file, the TAI offset couldn=E2=80=99t be read correctly. =
Removing the TAI directive resulted in a 37-second offset, and enabling =
it again produced no usable time source.
Once I restored the correct tzdata files, everything returned to normal.
Reference ID : 50484330 (PHC0)
Stratum : 1
Ref time (UTC) : Mon Nov 24 12:32:38 2025
System time : 0.000000001 seconds fast of NTP time
Last offset : +0.000000003 seconds
RMS offset : 0.000000016 seconds
Frequency : 13.669 ppm slow
Residual freq : +0.000 ppm
Skew : 0.005 ppm
Root delay : 0.000000001 seconds
Root dispersion : 0.000000911 seconds
Update interval : 1.0 seconds
Leap status : Normal
MS Name/IP address Stratum Poll Reach LastRx Last sample =
=20
=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
#* PHC0 0 0 377 0 +55ns[ +59ns] +/- =
38ns
^- time-a-g.nist.gov 1 10 377 117 -35ms[ -35ms] +/- =
140m
That NIST will go away shortly - it was there to attempt to work out =
what was going on with my PHC and work out if it was actually working or =
not.=20
> On 24 Nov 2025, at 21:39, Miroslav Lichvar <[email protected]> =
wrote:
>=20
> On Sun, Nov 23, 2025 at 09:23:05PM +1300, Chris Hodgetts wrote:
>> Hello,=20
>>=20
>> I have just upgraded to chrony version 4.6.1 on Debian 13=20
>>=20
>> I have noticed my PTP time has not failed, and it appears to be when =
I put :=20
>>=20
>> refclock PHC /dev/ptp0 poll 0 dpoll 0 tai
>>=20
>> If I remove tai - I get 37 second offset and Chrony does not sync to =
PTP.
>=20
> What exactly failed means here? Not being selected for
> synchronization? Please provide output from the chronyc sources
> command.
>=20
> How is the PHC synchronized? Is it ptp4l?
>=20
> --=20
> Miroslav Lichvar
>=20
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<html aria-label=3D"message body"><head><meta http-equiv=3D"content-type" =
content=3D"text/html; charset=3Dutf-8"></head><body =
style=3D"overflow-wrap: break-word; -webkit-nbsp-mode: space; =
line-break: after-white-space;"><p data-start=3D"232" data-end=3D"239" =
style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">Hello,</p><p =
data-start=3D"241" data-end=3D"299" style=3D"caret-color: rgb(0, 0, 0); =
color: rgb(0, 0, 0);">Just a quick follow-up in case anyone else runs =
into this.</p><p data-start=3D"301" data-end=3D"550" style=3D"caret-color:=
rgb(0, 0, 0); color: rgb(0, 0, 0);">I was initially seeing all zeros =
and a =E2=80=9C?=E2=80=9D on the PHC source line, which made it look =
like chrony wasn=E2=80=99t treating the PHC as a valid source, but there =
were no errors when iit started, or that I could see in any =
log. </p><p data-start=3D"301" data-end=3D"550" style=3D"caret-color:=
rgb(0, 0, 0); color: rgb(0, 0, 0);">I originally suspected a chrony =
issue after upgrading, but it turned out not to be related to chrony at =
all.</p><p data-start=3D"552" data-end=3D"853" style=3D"caret-color: =
rgb(0, 0, 0); color: rgb(0, 0, 0);">The actual cause was that <code =
data-start=3D"578" data-end=3D"589">right/UTC</code> was no longer =
present in my tzdata after upgrading to Debian 13 (at least on my =
system). </p><p data-start=3D"552" data-end=3D"853" =
style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">Without that =
file, the TAI offset couldn=E2=80=99t be read correctly. Removing the =
TAI directive resulted in a 37-second offset, and enabling it again =
produced no usable time source.</p><p data-start=3D"855" data-end=3D"957" =
style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">Once I =
restored the correct tzdata files, everything returned to =
normal.</p><div><span style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, =
0, 0);">Reference ID : 50484330 =
(PHC0)</span></div><div><span style=3D"caret-color: rgb(0, 0, 0); color: =
rgb(0, 0, 0);">Stratum : =
1</span></div><div><span style=3D"caret-color: rgb(0, 0, 0); color: =
rgb(0, 0, 0);">Ref time (UTC) : Mon Nov 24 12:32:38 =
2025</span></div><div><span style=3D"caret-color: rgb(0, 0, 0); color: =
rgb(0, 0, 0);">System time : 0.000000001 seconds fast of =
NTP time</span></div><div><span style=3D"caret-color: rgb(0, 0, 0); =
color: rgb(0, 0, 0);">Last offset : +0.000000003 =
seconds</span></div><div><span style=3D"caret-color: rgb(0, 0, 0); =
color: rgb(0, 0, 0);">RMS offset : 0.000000016 =
seconds</span></div><div><span style=3D"caret-color: rgb(0, 0, 0); =
color: rgb(0, 0, 0);">Frequency : 13.669 ppm =
slow</span></div><div><span style=3D"caret-color: rgb(0, 0, 0); color: =
rgb(0, 0, 0);">Residual freq : +0.000 ppm</span></div><div><span =
style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">Skew =
: 0.005 ppm</span></div><div><span =
style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">Root delay =
: 0.000000001 seconds</span></div><div><span =
style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">Root =
dispersion : 0.000000911 seconds</span></div><div><span =
style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">Update =
interval : 1.0 seconds</span></div><p data-start=3D"855" data-end=3D"957" =
style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">Leap status =
: Normal</p><p data-start=3D"855" data-end=3D"957" =
style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, =
0);"><br></p><div><span style=3D"caret-color: rgb(0, 0, 0); color: =
rgb(0, 0, 0);">MS Name/IP address Stratum =
Poll Reach LastRx Last sample =
</span></div><div><span style=3D"caret-color: rgb(0, 0, 0); =
color: rgb(0, 0, =
0);">=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D</span></div><div><span style=3D"caret-color: rgb(0, =
0, 0); color: rgb(0, 0, 0);">#* PHC0 =
0 0 =
377 0 +55ns[ +59ns] +/- =
38ns</span></div><p data-start=3D"855" data-end=3D"957" =
style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">^- =
time-a-g.nist.gov 1 10 =
377 117 -35ms[ -35ms] +/- =
140m</p><p data-start=3D"855" data-end=3D"957" style=3D"caret-color:=
rgb(0, 0, 0); color: rgb(0, 0, 0);"><br></p><div><div><div>That NIST =
will go away shortly - it was there to attempt to work out what was =
going on with my PHC and work out if it was actually working or =
not. </div><div><br></div><div><br><blockquote type=3D"cite"><div>On =
24 Nov 2025, at 21:39, Miroslav Lichvar <[email protected]> =
wrote:</div><br class=3D"Apple-interchange-newline"><div><div>On Sun, =
Nov 23, 2025 at 09:23:05PM +1300, Chris Hodgetts wrote:<br><blockquote =
type=3D"cite">Hello, <br><br>I have just upgraded to chrony version =
4.6.1 on Debian 13 <br><br>I have noticed my PTP time has not failed, =
and it appears to be when I put : <br><br>refclock PHC /dev/ptp0 poll 0 =
dpoll 0 tai<br><br>If I remove tai - I get 37 second offset and Chrony =
does not sync to PTP. <br></blockquote><br>What exactly failed means =
here? Not being selected for<br>synchronization? Please provide output =
from the chronyc sources<br>command.<br><br>How is the PHC synchronized? =
Is it ptp4l?<br><br>-- <br>Miroslav =
Lichvar<br><br></div></div></blockquote></div><br></div></div></body></htm=
l>=
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