GPS NTP reference clock

Question

Hej,
I do have a problem on my OSX 10.6.6 Server - I cannot successfully connect a GPS receiver for my NTP service.
What I did works perfectly on OSX 10.6.6 client, but on the server it fails with
fcntl(F_SETOWN) fails for clock I/O: Inappropriate ioctl for device
The device is a HOLUX GM-210, connected via USB (PL2303 driver from Prolific)
works fine with cu, but not with the bundled ntpd.
I looked around, but only found one with the exact same problem back in 2004, but his question was never answered.
So what might be the reason for this behavior, and how to fix it?

Answer 1

MrHoffman wrote:
To clarify my understanding of the current configuration: setting the 127.127.20.0 driver doesn't get accepted via Server Admin, or that reference clock driver value is accepted but no synchronization happens? (I'd tend to expect it to be accepted, but that you're not getting a lock?)
Yes, serveradmin accepts that happily, but it does not show up as a valid peer.
if you're messing with the ntp configuration files (and adding stuff), try putting your additional lines after a # line or two. (The comment characters will reportedly keep Server Admin from stepping on your changes. This is one of the differences between Mac OS X and Linux distributions.)
Thanks for this valuable tip.
What does +ntpq -p+ show?
schneekoenig:~ oskar$ ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
*time.euro.apple 17.72.133.54 2 u 772 68m 377 56.646 9.836 0.607
so, basically, the 127.127.20.0 does not show up.
Given the pl2303 stuff usually instantiates itself as a USB TTY device (/dev/ttyUSBxyz something or other? I run with another series of USB-to-serial widgets, so I will not see the same device names here as you'll get), and you might (will?) need to add a link to instantiate an appropriately-named a gps device for the NTP software to find. (Get a full disk backup first!) Something akin to this +ln -s /dev/whatever /dev/gps0+ command, given that the ntp daemon expects gps devices such as the /dev/gps0, gps1 or gps2 devices. Given you're using 127.127.20.0, the target device ntp will look for here is /dev/gps0, while 127.127.20.1 would seek /dev/gps1, etc. (Again, please make a full disk external backup before you go working with links in /dev given mistakes here can be deadly to OS stability. I'd suggest rebooting immediately after adding the link into /dev, too, to ensure ntp and the rest of the box reboots with happy-bits and not sad-bits.)
done all that before asking here
Once you reboot, try that +ntpq -p+ command, and see if you get non-zero values associated with your selected time base.
I'd guess you might have to play with the mode setting, too. (I'd likely try getting this to work with a one-line server command first, no mode, no other options, etc.)
I guess the problem is more likely in the way OSX Server handles the usbserial device. The exact same configuration works just fine on SnowLeopard 10.6.6 Client. Hmm, the client runs a 32 bit kernel, whereas the Server is in native 64 bit. Maybe the Prolific driver is not complete, in that fcntl(F_SETOWN) does not return the expected results in 64 bit mode. As stated before, ntpd finds the correct serial port, opens it successfully but then fails on the fcntl system call.
Jan 20 09:45:36 schneekoenig org.ntp.ntpd[25567]: refclock_setup fd 5 modem status: 0x6Jan 20 09:45:36 schneekoenig org.ntp.ntpd[25567]: refclock_ioctl: fd 5 flags 0x1
Jan 20 09:45:36 schneekoenig org.ntp.ntpd[25567]: addto_syslog: fcntl(F_SETOWN) fails for clock I/O: Inappropriate ioctl for device
Jan 20 09:45:36 schneekoenig org.ntp.ntpd[25567]: addto_syslog: configuration of 127.127.20.0 failed