nmea refclock not locking to the pps

[Gary E. Miller]

Yo Tony!

On Fri, 10 Mar 2017 10:54:55 -0800
"Tony Hain" <tony at tndh.net> wrote:

> Gary E. Miller wrote:
> > Yo Tony!
> > 
> > I'm baffled, I have been running gpsd on IPv6 hosts for almost a
> > decade, and I have never had to ask for the ipv6 option.
> > 
> > Can you dig into this some more?  Something else is going on.  
> 
> IPv6 is default-on, UNLESS you follow the instructions at
> http://www.catb.org/gpsd/gpsd-time-service-howto.html
> because as soon as you say  timeservice=yes  SConstruct stops
> building it (and the clients) as shown in the script block I pasted
> in below.

I passed that on the Eric, the author of the timeservice option.  He
confirmed what you saw.  Which I think is a bad thing.

I'll beat on him to fix that.  He went overboard on minimalism.

> > Also, you are mixing gpsd problems, which belong on the gpsd list.
> > And ntpsec problems which belong here.  Can you split off you gpsd
> > comment and send that to gpsd-users?  
> 
> I thought about that, but we got here because you wanted me to run
> gpsd instead of nmea.

Well, that was before you told me you were on FreeBSD.  But once
you are on gpsd, that becomes a gpsd problem.  So belongs on there
list where their maintainters see it.

The gpsd people knew there were issues with PPS on FreeBSD.  I hope
you submit your patches to them so progress can be made on them.

> I
> know people use it, but if the interface is not as crisply defined as
> people think it is,

We can't change it, too many projects use it.  And it makes sense to
me, but I am too close to it.  If you have any doc suggestions
send them on.

> there may be an oversight which allows ntpshmmon
> to show events while the ntpsec SHM driver fails.

I know of no such thing.  Details?

> I can resend that under a different subject if that is necessary.

Please do, best to have on bug per thread.

> At this point I believe my original issue with the offset is more
> readily explained by an asymmetry in the stack. OWAMP
> (http://software.internet2.edu/owamp/) shows a consistent difference
> in ping times between systems on the same switch, or 1-2 local router
> hops away in packets originating from vs. echo'd by the FreeBSD-12
> stack.

Which is pretty much what I was trying to tell you.  Easily seen with
ntpviz.  Fix your prefers and that goes away.  Yu got a local GPS, make
sure it is being used as primary time source.

> That indicates the original concern is not likely to be an
> ntpsec issue, though there were still differences between it and
> 4.2.8p9 which I will get back to if the asymmetry can be resolved.

If you figure out a solution a ton of people would be interested.  That
has been bothering people a long time, and the reason why local GPS
are so popular.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin
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