[ntp:hackers] Any NetBSD and/or tty ioctl gurus?

Hal Murray hmurray at suespammers.org
Tue Dec 27 08:11:01 UTC 2005


I'm trying to setup 3 refclocks on a vanilla PC running NetBSD 3.0 and ntp-dev

The first clock works but the other two get this:

26 Dec 21:13:05 ntpd[821]: ioctl(TIOCSCTTY, 0) fails for clock I/O: Operation 
not permitted
26 Dec 21:13:05 ntpd[821]: configuration of 127.127.20.2 failed
26 Dec 21:13:06 ntpd[821]: ioctl(TIOCSCTTY, 0) fails for clock I/O: Operation 
not permitted
26 Dec 21:13:06 ntpd[821]: configuration of 127.127.26.3 failed

The only place I find any reference to TIOCSCTTY is in libntp/iosignal.c

I'm not familiar with the tty ioctls.  The comment a few lines up is 
suspicious:
                 * another question is: how can you do multiple SIGIO from 
several
                 * ttys (as they all should be CTTYs), wondering...

Anybody recognize this quirk?  Does NetBSD just not support more than one 
refclock?

Seems to be that way.  I found a note from the NetBSD on AMD-64 list that 
says only one.  (0 if in debug mode.)  It also says:
  For SIGIO you need a CTTY.
    There can only be one CTTY.
    Thus you can get only SIGIO from one CTTY. This seems
    to be the case with many BSD derived systems (*BSD, Ultrix).

Looks like everybody agrees that this path won't work.

How does this work on FreeBSD?  Is there any good documentation for the tty 
ioctls and/or is there a reasonable chance of fixing this on NetBSD?

I've seen suggestions of using the parallel port.  (I don't remember if that 
was for 1 PPS signal or several.)  I'd like to avoid that mostly for 
mechanical reasons.


Maybe I should pop up a level.  Is this a strange configuration?  Is it silly 
to use more than one refclock on a system?  I was hoping to be able to 
compare clocks.



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