[Linuxptp-users] UTC Offset on grandmaster?

[Scott S. <ssi...@si...>]

I recently ran into an issue where slaves were all off by exactly one
second. I believe that the UTC offset was the source of this issue.

Running linuxptp as grandmaster, the "currentUtcOffset" is reported as 35,
and "currentUtcOffsetValid" is reported as 0:

# pmc -u -b 0 'get TIME_PROPERTIES_DATA_SET'
sending: GET TIME_PROPERTIES_DATA_SET
0cc47a.fffe.63397c-0 seq 0 RESPONSE MANAGMENT TIME_PROPERTIES_DATA_SET
currentUtcOffset      35
leap61                0
leap59                0
currentUtcOffsetValid 0
ptpTimescale          1
timeTraceable         0
frequencyTraceable    0
timeSource            0xa0

It is my understanding that the current UTC/TAI offset is 36. In fact,
slaves (behind boundary clocks) report a UTC/TAI offset of 36:

Here is the output from one slave (behind a single boundary clock):
# pmc -u -b 0 'get TIME_PROPERTIES_DATA_SET'
sending: GET TIME_PROPERTIES_DATA_SET
0cc47a.fffe.3a2c5c-0 seq 0 RESPONSE MANAGMENT TIME_PROPERTIES_DATA_SET
currentUtcOffset      36
leap61                0
leap59                0
currentUtcOffsetValid 1
ptpTimescale          1
timeTraceable         0
frequencyTraceable    0
timeSource            0xa0



I'm running linuxptp (1.5) on CentOS6 (kernel 4.0.4).

I am running phc2sys with the following configuration:
-s CLOCK_REALTIME -c eth0

I am running ptp4l with the following configuration:
-i eth0 -f /etc/ptp4l.conf

My ptp4l.conf is the package default, with the exception of the priority1
(set to 125).

I tried adding a "-O 36" to the phc2sys command line, but it had no effect
on the reported UTC offset.





Thanks,

Scott Silverman

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