[ntp:questions] Change poll interval at runtime?

A C agcarver+ntp at acarver.net
Mon Feb 27 22:34:48 UTC 2012

On 2/26/2012 23:38, David J Taylor wrote:
> "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?

Zilog was completely standard on sun4c and sun4m so it's neither case of 
non-standard nor faulty hardware.  It's just different (but standard for 
the architecture).  It also hasn't been fully worked through likely 
because the much more recent Sun hardware had shifted to other hardware 
components in an effort to reduce costs.  Eventually, of course, Sun 
switched architectures entirely and the latest Sun hardware has an Intel 
based design rather than the orignal Sun RISC processor designs.

> http://www.oracle.com/technetwork/server-storage/solaris11/downloads/index.html
> I don't know about earlier versions....

Unless someone has a copy on CD laying around the earlier versions I 
can't get one from Oracle anymore.

>> 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".

I have grander plans for the GPS besides timekeeping so I want to have 
it running in SiRF mode which requires gpsd to translate the data and 
send it over to ntpd for time.  But as long as PPS+Internet work then 
it's good enough for timing.  One Internet server is set to prefer 
already so it does pick up on PPS after the servers have been polled a 
few times.  They are just forever stuck at 64 second intervals.

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