[ntp:questions] Change poll interval at runtime?

A C agcarver+ntp at acarver.net
Mon Feb 27 06:26:34 UTC 2012


On 2/26/2012 22:02, David J Taylor wrote:
> "A C" <agcarver+ntp at acarver.net> wrote in message
> news:4F4A8863.2010401 at acarver.net...
> []
>> FreeBSD's serial drivers are also very broken (in fact, even more
>> broken than NetBSD because FreeBSD can't even see the DCD line).
>
> This sounds like you have faulty hardware. There has been no problem
> with FreeBSD drivers on the two different PCs I've tried - other than
> determining what name has been given to the serial port....

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.

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).


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