[ntp:questions] ntpd writes H/W clock?

martin rogers martin.rogers at windriver.com
Tue Dec 19 23:15:16 UTC 2006


All,

I have set up NTP on a small network of widgets running linux 2.6.14,  and
there is a reqmnt that all widgets maintain their times to within a 
certain amount
of each other. 

One machine serves time to the others.  Periodically, the server must 
dial out
and update his own time from us.pool.ntp.org or whatever (right now my
scheme is to kill ntpd, dial out, do a ntpdate, hang up, and restart 
ntpd.  I gather
this is unconventional, but not my biggest worry right now).

I was asked to set up the server so that periodically, hwclock -s  will run
(to copy our very accurate HW clock time to the system time, which seems
to have ~2 sec per day error).  However, I have found that ntpd is 
writing to
the HW RTC.

Why, and when ?  Ntpd didn't complain before I enabled the H/W RTC in
my kernel- now that it is, it's being written.

I haven't found any docs that cover this- can someone shed light?

TIA all..

Martin Rogers






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