On Friday 26 October 2007, Rob Janssen wrote: > Dag-Erling Smørgrav wrote: > > Chuck <[EMAIL PROTECTED]> writes: > > > >> anyone know if i run freebsd with pps turned on in the kernel and the > >> ntpd set to kernel pps if i also load gpsd not to feed ntpd as it will > >> never have the server info in it, but to allow telnet and web > >> interfaces into checking satellite coverage etc, will gpsd interfere > >> with the kernel processing the time properly? > >> > > > > It won't. All gpsd does is provide a convenient interface to a GPS > > receiver; it does not touch the clock. > > > > DES > > > On the other hand, the ntp driver for the gps receiver will probably not > work when gpsd is running. > When locking on PPS, you need two types of information: > - absolute time, to get the clock set within a second > - PPS pulses, which only provide information about the exact time the > seconds tick, but not the time of day it is. > > The GPS drivers in ntpd do read the serial stream from the receiver to > know the time of day, and use the PPS pulses to provide accurate sync. > When such a driver reads the serial stream, it no longer is available > for other programs that e.g. want positioning information, like gpsd. > > That is why time suppport was built into gpsd. gpsd reads the serial > stream and can also monitor the pps. It makes it available as two > shared memory areas that ntpd can use: 1 with the info from the serial > stream, and 1 with the PPS information. > > When you setup gpsd and use the first clock for acquisition with ntpd > and use the PPS pulses as direct input to the kernel, I think ntpd will > get confused. But maybe not, you could try. > > But in any case you should not use gpsd together with one of the gps > drivers in ntpd. That would require some "tee" functionality that > splits the received gps serial stream in two directions. > > Rob >
hmm... thing is ntpd shouldnt know about gpsd at all if the driver is not in ntpd. i have no intention to use the gpsd driver in any timekeeping functions. what i will use is this # server 127.127.20.1 mode 1 prefer # fudge 127.127.20.1 time1 0.000 flag3 1 refid PPS to enable the kernel pps mode and to use our ACTS server as the one server for timekeeping data. was intending to load gpsd only to serve port 2947 for sat count/positioning web information. i guess my biggest concern was if either ntpd or gpsd opened the serial port in exclusive mode which would then not allow the 2 to share it. -- Chuck "...and the hordes of M$*ft users descended upon me in their anger, and asked 'Why do you not get the viruses or the BlueScreensOfDeath or insecure system troubles and slowness or pay through the nose for an OS as *we* do?!!', and I answered...'I use Linux'. " The Book of John, chapter 1, page 1, and end of book _______________________________________________ timekeepers mailing list [email protected] https://fortytwo.ch/mailman/cgi-bin/listinfo/timekeepers
