Re: [chrony-users] /dev/rtc locked while chrony is running

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On Tue, 25 Sep 2012, Wickham, Mark wrote:


I am quite pleased with the capabilities of chrony and I find it to work well.

From the documentation of rtcfile:

3.  You don�t have other applications that need to make use of �/dev/rtc� at all.

Is this still the situation?  I would like to be able to implement other applications that use the RTC.  What are my options?

The use of rtc by chrony is not really terribly useful anymore. i) chrony measures the drift when the computer is running ( and it fluctuates
by up to 10PPM) but the drift is useful for resetting the computer clock after
the machine has been off for a while (ie cold) This means that the actual rate
of the rtc may be tens of PPM off from that measured ( which itself is an
"instantaneous" measurement of the rate error.)

ii) The rtc has become rather flaky since the old legacy version disappeared
into hpet. The interrupt driven rtc has been replaced by a polled rtc which is
much less accurate.

Why do you want to use the rtc? What do you want to do with it?

 beleive that the main point of that comment is that if anything alters the
rtc, then chrony cannot keep track of the drift of the rtc, since it has no
idea something else changed it.


Mark Wickham
Digi International
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