[time-nuts] OpenBSD / ntpd / gpsd / PPS problems

Hal Murray hmurray at megapathdsl.net
Sun Oct 25 04:56:22 UTC 2009


> Despite the claim (see above) that gpsd uses OpenBSD's NMEA line
> discipline to export PPS time stamps, I can't find any substantiation
> for this in the gpsd source code.  I tried enabling the NMEA line
> discipline manually on the GPS's serial port (via the ldattach
> command), but this made gpsd totally unable to read anything from the
> GPS at all. 

I'm not sure what "line discipline" means.

I think what gpsd is doing is just watching the carrier line and grabbing the 
time when it changes.  I took a quick look at some old source code, and I see 
things like this:
  if defined(PPS_ENABLE) && defined(TIOCMIWAIT)
(There might be other code that uses the kernel time-stamping stuff, but I 
didn't see it.)

If that's the case, then there is nothing special about OpenBSD.  You might 
have an easier time getting things going on an OS that you are more familiar 
with.




-- 
These are my opinions, not necessarily my employer's.  I hate spam.






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