Re: char-major-10-135

[Raghavendra Bhat <ragu@vsnl.com>]

Ethan posts:

> hwclock uses it to update the hardware clock, this
> is done at shutdown to keep the clocks synchronized.  

Agreed that 'hwclock' updates the hardware clock
while shutting down the m/c.  This does not have 
anything to do with the 'rtc' module and hwclock does
in no way use it.  The 'rtc' module gives you access
to the real time clock (or hardware clock) built 
into your computer.

Yup, it is a good thing to have rtc support if you do 
data sampling work or on an SMP machine.  Otherwise
it is not needed for a reasonably stable CMOS clock
that you normally have on your uniprocessor m/b.
It should not drift, that is you should have a stable
clock tick.

The hardware clock is synced with the system clock,
when you go down with an init 0/6.  I think that the
system clock can adjust a drifting hardware clock.
How was the system clock set ?  It was set from the
hardware clock when you booted up.  See the script 
hwclock.sh in /etc/rcS.h.  So, is 'rtc' really 
needed ?  I would say no. Correct me if I am wrong,
tnx anyway.

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