[ntp:questions] Change poll interval at runtime?

David J Taylor david-taylor at blueyonder.co.uk.invalid
Mon Feb 27 07:38:47 UTC 2012

"A C" <agcarver+ntp at acarver.net> wrote in message 
news:4F4B221A.6020001 at acarver.net...
> Sun sparc (Zilog serial ports), not Intel/AMD.  FreeBSD has different 
> serial drivers for different architectures.  The hardware I have is not 
> faulty.  Under Solaris it all works (but I don't have a copy of Solaris 
> 7 around to support sun4c architecture).  NetBSD supports sun4c and can 
> see DCD just fine but it's unable to share half of the port (TX/RX) with 
> one process while sharing the other half (DCD, RTS, CTS) with another 
> process (this is what makes its serial port support broken).  FreeBSD's 
> sparc serial driver is unable to read the control lines so it's very 
> broken.

So non-standard hardware rather than faulty hardware.  BTW: I thought that 
one of the benefits of open-course operating systems was that you could 
fix such problems yourself!  A pity no-one has fixed the driver.  I had 
also thought that Solaris was now free to download by anyone, and use for 
non-production use, but perhaps I'm wrong?


I don't know about earlier versions....

> The sharing of a serial port is critical for ntpd to do PPS on the NMEA 
> refclock.  On Solaris 7 this would probably work fine.  On NetBSD, ATOM 
> or NMEA without PPS work but NMEA with PPS does not.  On FreeBSD, forget 
> PPS entirely.  This is why my GPS data is coming in on serial port A and 
> my PPS signal is coming in on serial port B.  I have to split them up to 
> see both on NetBSD which means I need two refclocks, one PPS and one 
> NMEA (or SHM for when I have gpsd manage the GPS in SiRF mode).

The GPS/PPS devices I have either require no management (the Sure board), 
or need just a one-time setup under Windows for the Garmin GPS 18/x LVC. 
There's no need for any routine interaction.  My own tests with serial 
GPS/NMEA data alone support the view that it's no better than just using 
Internet servers, so Internet + PPS may be your best solution, and not 
worry too much if the Internet servers never ramp up to 1024s poll.  You 
didn't say whether one of the Internet servers was marked "prefer".


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