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      1 HP e3000 MPE/iX NTP Hints - May 29, 2001
      2 ----------------------------------------
      3 
      4 NTP was first ported to MPE several years ago, but those diffs were never
      5 submitted back to the official NTP distribution.  For more information about
      6 that deprecated port, please see http://www.bixby.org/mark/xntpix.html.
      7 
      8 NTP was re-ported to MPE in May 2001.  What follows are hints learned from
      9 working with NTP 4.0.99k23.  For additional information about NTP on MPE,
     10 please see http://jazz.external.hp.com/src/hp_freeware/ntp/.
     11 
     12 MPE lacks the clock-related APIs expected by NTP, so adjtime(), gettimeofday(),
     13 and settimeofday() all had to be implemented from scratch by calling
     14 privileged, undocumented internal OS functions.
     15 
     16 Unfortunately the implementation of adjtime() has exposed a sub-second accuracy
     17 bug when slewing the system time.  This bug is documented in SR 5003462838, and
     18 exists on all current versions of MPE.  It has not been fixed at the time of
     19 this writing.  The adjtime() code may possibly need to be altered if/when this
     20 bug is fixed.
     21 
     22 This bug has a side-effect whereby the ntpd daemon will screw up the hardware
     23 PDC clock time by many minutes if used for continuous clock adjustments or in
     24 the one-time -q mode.  But note that you can safely run ntpd in order to become
     25 a time server if you include "disable ntp" in the ntp.conf configuration file.
     26 
     27 The one-time clock adjustment functionality of ntpdate and ntp_timeset is not
     28 affected by this bug side-effect.  You can safely use these commands to alter
     29 your system time with reasonable accuracy.
     30 
     31 The only reference clock that has been tested on MPE is the local clock.  So
     32 building NTP with --disable-all-clocks --enable-LOCAL_CLOCK is strongly
     33 recommended.
     34 
     35 NTP makes use of Privileged Mode (PM) capability in order to bind to the NTP
     36 network port (123) and to access the low-level clock functions.
     37 
     38 NTP was ported using the gcc compiler.  Attempting to use the HP C/iX compiler
     39 is not recommended and has not been tested.
     40 
     41 Please note that NTP is not an HP product and is NOT supported by HP.  The best
     42 place for asking MPE-specific questions about NTP is the HP3000-L mailing list
     43 at http://raven.utc.edu/Archives/hp3000-l.html or the associated Usenet
     44 newsgroup of comp.sys.hp.mpe.
     45 
     46 The original author of this port is:
     47 
     48 Mark Bixby
     49 HP CSY MPE Internet & Interoperability Engineer
     50 mark_bixby (a] hp.com
     51