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 1HP e3000 MPE/iX NTP Hints - May 29, 2001
 2----------------------------------------
 3
 4NTP was first ported to MPE several years ago, but those diffs were never
 5submitted back to the official NTP distribution.  For more information about
 6that deprecated port, please see http://www.bixby.org/mark/xntpix.html.
 7
 8NTP was re-ported to MPE in May 2001.  What follows are hints learned from
 9working with NTP 4.0.99k23.  For additional information about NTP on MPE,
10please see http://jazz.external.hp.com/src/hp_freeware/ntp/.
11
12MPE lacks the clock-related APIs expected by NTP, so adjtime(), gettimeofday(),
13and settimeofday() all had to be implemented from scratch by calling
14privileged, undocumented internal OS functions.
15
16Unfortunately the implementation of adjtime() has exposed a sub-second accuracy
17bug when slewing the system time.  This bug is documented in SR 5003462838, and
18exists on all current versions of MPE.  It has not been fixed at the time of
19this writing.  The adjtime() code may possibly need to be altered if/when this
20bug is fixed.
21
22This bug has a side-effect whereby the ntpd daemon will screw up the hardware
23PDC clock time by many minutes if used for continuous clock adjustments or in
24the one-time -q mode.  But note that you can safely run ntpd in order to become
25a time server if you include "disable ntp" in the ntp.conf configuration file.
26
27The one-time clock adjustment functionality of ntpdate and ntp_timeset is not
28affected by this bug side-effect.  You can safely use these commands to alter
29your system time with reasonable accuracy.
30
31The only reference clock that has been tested on MPE is the local clock.  So
32building NTP with --disable-all-clocks --enable-LOCAL_CLOCK is strongly
33recommended.
34
35NTP makes use of Privileged Mode (PM) capability in order to bind to the NTP
36network port (123) and to access the low-level clock functions.
37
38NTP was ported using the gcc compiler.  Attempting to use the HP C/iX compiler
39is not recommended and has not been tested.
40
41Please note that NTP is not an HP product and is NOT supported by HP.  The best
42place for asking MPE-specific questions about NTP is the HP3000-L mailing list
43at http://raven.utc.edu/Archives/hp3000-l.html or the associated Usenet
44newsgroup of comp.sys.hp.mpe.
45
46The original author of this port is:
47
48Mark Bixby
49HP CSY MPE Internet & Interoperability Engineer
50mark_bixby@hp.com