Question for 3b4000 gurus...
Andy S Poling
andy at jhunix.HCF.JHU.EDU
Wed Feb 6 07:24:23 AEST 1991
I'm attempting to impliment NTP on our 3b4000 and I'm having some trouble
figuring out how to twiddle the clock in teeny weeny little incriments. The
ntpd sources for BSD-based systems use adjtime() which essentially changes
the ticks required to make one second up and down - essentially minutely
slowing or speeding up the clock.
Needless to say, we have no adjtime() call (that I know of). What I have
found are some interesting kernel symbols and an interesting ABUS ioctl.
The kernel symbols are
lticks varies between 99 and 100 (indicating to me that
something is already wiggling it)
ticspersec value is 100
one_sec counts from 0 to 100, apparently for each second
The ABUS ioctl is C_EPOCH which TFM says "toggles the epoch bit so that the
system time can be set backwards". Isn't that a lucid explanation?
Since AT&T has refused us kernel source, I can only guess at what the above
kernel symbols really are. Since the available ntpd sources are designed to
fudge the clock in very little pieces (like a couple ms) at a time, I find
twiddling a value in the kernel a more attractive option. Otherwise I'll
have to extensively modify the ntpd sources to intentionally make them less
accurate (a shame, really) and do repeated stime()s to slowly approach the
correct time.
I'm also assuming that the clock on the MP is the one that matters and that
I would only have to twiddle values in the MP's kernel. Stupid
assumption?
Any suggestions or ideas? Anybody done this before/already? I would
appreciate any help at all.
-Andy
--
Andy Poling Internet: andy at gollum.hcf.jhu.edu
UNIX Systems Programmer Bitnet: ANDY at JHUNIX
Homewood Academic Computing Voice: (301)338-8096
Johns Hopkins University UUCP: uunet!mimsy!aplcen!jhunix!andy
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