[ntp:questions] PPS not working on newer kernel/distros

Brandon Applegate brandon at burn.net
Sun Oct 14 20:22:56 UTC 2018

> On Oct 14, 2018, at 1:16 PM, Vitezslav Samel <vitezslav at samel.cz> wrote:
>  In case of 'flag3 0' you are using userlevel PPS handling, in case of
> 'flag3 1' and proper kernel support (and proper timepps.h header file
> and properly compiled ntpd sources) you are using kernel PPS.
>  To have proper kernel PPS support you need to have timepps.h header
> file from git://github.com/ago/pps-tools.git installed in the right
> place and then ntpd sources recompiled. timepps.h file from this
> repository has properly implemented the time_pps_kcbind() function.

Hey Vita,

I think I’m following what you are saying.  I definitely have timepps.h in the right place and ntpd compilation / configuration confirms it’s found and happy.

What I’m experiencing is that it will run with flag3 set to 1 - but it never seems to ‘lock on’ to PPS.  I’m wondering / asking if this could be a kernel issue.  I know I’m not giving kernel versions etc. and I’m speaking in terms of linux distro version.  I suppose I could nail down versions and try to dig to see if there’s PPS changes that have been made (for the worse) over the years.  I was just hoping perhaps someone on this list would know offhand of a ’smoking gun’ WRT linux kernel version / changes that has (adversely) affected kernel PPS.

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