A-UX Hints

Last update: May 4, 2022 17:05 UTC (dbea9b7d4)

Introduction

Included in this distribution of XNTP V3 is a configuration file suitable for use under Apple’s A/UX Version 3.x.x There is also one for A/UX 2.0.1 but it has not been fully tested. To make the executables follow the steps outlined below.

NOTE: You must have gcc installed to successfully compile the current distribution; the native cc supplied with A/UX will NOT correctly compile this source. See the FAQ in comp.unix.aux for places to obtain gcc from and how to install it.

Making XNTPD for A/UX

First, you need to create the makefiles (after you’ve downloaded the source, of course):

make clean

make refconf

After that, you should edit Config.local to make sure that BINDIR is correct for where you wish the programs to be installed. The default (and what I use) is /usr/local/etc. Make sure that DEFS_LOCAL and CLOCKDEFS are commented out! Presently, only the LOCAL_CLOCK/REFCLOCK clock is used and supported.

After this is done (you should be told that your system is A/UX 3), make xntpd (the options to gcc are held in compilers/aux3.gcc):

make

I do not normally use the make install option and so have not verified its compatibility with A/UX. Rather, I pull out each of the executables and place them in the locally appropriate locations.

Starting XNTPD

At this point you need to set things up so that xntpd is started upon boot-up. You can do this in 1 of 2 ways: either add entries in /etc/inittab or, more ideally, create and use an /etc/rc.local file. Since rc.local is what I recommend, here’s how you do it:

By default, A/UX doesn’t have rc.local, so you’ll need to add the following to /etc/inittab:

net6:2:wait:/etc/syslogd		        # set to "wait" to run a syslog daemon
jmj0:2:wait:/etc/rc.local 1>/dev/syscon 2>&1	# Local stuff
dbg2::wait:/etc/telinit v	                # turn off init's verbose mode

Now, the look of a sample /etc/rc.local is as follows:

#!/bin/sh
:
: rc.local
:
#	@(#)Copyright Apple Computer 1987	Version 1.17 of rc.sh on 91/11/08 15:56:21 (ATT 1.12)

#	Push line discipline/set the device so it will print
/etc/line_sane 1
echo " "
echo "Entering rc.local..."

set `/bin/who -r`
if [ "$7" = 2 ]
then
    /bin/echo " now setting the time..."
    /usr/local/etc/ntpdate -s -b <host.domain>
    sleep 5
#
# start up 'xntpd' if we want
#
    if [ -f /etc/ntp.conf ]
    then
	/bin/echo " setting tick and tickadj..."
	/usr/local/etc/tickadj -t 16672 -a 54
	sleep 5
	/bin/echo " starting xntpd..."
	/usr/local/etc/xntpd <&- > /dev/null 2>&1
	sleep 5
    fi
#
fi

echo "Leaving rc.local..."

There are a few things to notice about the above:

Now Mac clocks are pretty bad and tend to be slow. So, instead of having A/UX add the default of 16666 ms every 1/60th of a second, you may want it to add more (or less) so that it keeps better time. The above value works for me but your best value may be different and will likely require some fooling around to find the best value. As a general rule of thumb, if you see xntpd make a lot of negative clock adjustments, then your clock is fast and you’ll need to decrease the value of tick. If your adjustments are positive, then you need to increase tick. To make a guess on how fast/slow your clock is, use ntpdate to sync your clock. Now watch xntpd and see how it operates. If, for example, it resets your clock by 1 second every 30 minutes, then your clock is (1/(30*60)) about 0.056% off and you’ll need to adjust tick by 16666*0.00056 or about 9 (i.e. tick should be ~16675 if slow or ~16657 if fast).

A/UX’s default value of tickadj is 1666 which is too big for xntpd so it also needs to be adjusted. I like using larger values than the recommended value of 9 for tickadj (although not anything near as big as 1666) since this allows for quick slews when adjusting the clock. Even with semi-large values of tickadj (~200), getting 5ms (1/200 s) accuracy is easy.

Finally, before A/UX and xntpd will work happily together, you need to patch the kernel. This is due to the fact that A/UX attempts to keep the UNIX-software clock and the Mac-hardware clock in sync. Neither the h/w or the s/w clock are too accurate. Also, xntpd will be attempting to adjust the software clock as well, so having A/UX muck around with it is asking for headaches. What you therefore need to do is tell the kernel not to sync the s/w clock with the h/w one. This is done using adb. The following is a shell script that will do the patch for you:

#! /bin/sh
adb -w /unix <<!
init_time_fix_timeout?4i
init_time_fix_timeout?w 0x4e75
init_time_fix_timeout?4i
$q
!

This must be done every time you create a new kernel (via newconfig or newunix) or else xntpd will go crazy.

History

John Dundas was the original porter of xntpd and a lot of the additions and A/UX-ports are from him. I got involved when I wanted to run xntpd on jagubox. It was also around this time that the base-patchlevel of xntpd changed relatively (the so-called “jones” version). Since then, I’ve been maintaining xntpd for A/UX for the xntp development team.

The original kernel patch (which patched time_fix_timeout) was from Richard Todd. I suggest patching init_time_fix_timeout which prevents time_fix_timeout from even being called.

Technical Notes

Good luck! If you have problems under A/UX feel free to contact me (e-mail is preferred).

Jim Jagielski               |  "That is no ordinary rabbit... 'tis the
                            |   most foul, cruel and bad-tempered
NASA/GSFC, Code 734.4       |   rodent you ever set eyes on"
Greenbelt, MD 20771         |                   Tim the Enchanter