Re: [Linuxptp-users] UTC Offset on grandmaster?

[Keller, J. E <jac...@in...>]

On Fri, 2015-09-18 at 09:01 -0500, Scott Silverman wrote:
> 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:
> 

Yes is is. There was just a patch to fix this sent to the mailing list.
You should be able to correct this via a management message though
using pmc.. use the GRANDMASTER_SETTINGS_NP, which is a non portable
extension of the management protocol for PTP, you can reset the UTC
offset to 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.
> 
> 

That isn't the correct option. I don't believe there is an actual
option here, but you should be able to use pmc to set this. It might be
worth adding a configuration option as well?

Regards,
Jake

> 
> 
> 
> Thanks,
> 
> Scott Silverman