[ntp:questions] ntpd and hw clock

Steve Kostecke kostecke at ntp.org
Fri Feb 27 18:10:11 UTC 2009

On 2009-02-27, Unruh <unruh-spam at physics.ubc.ca> wrote:

> Steve Kostecke <kostecke at ntp.org> writes:
>>On 2009-02-27, Nero Imhard <nim at pipe.nl> wrote:
>>> Silly indeed, but rather Linux-specific. No such kludge in FreeBSD
>>> afaik.
>>Why do you consider a periodic update of the RTC to be a kludge?
> Because it does not allow one to determine the frequency offset of
> the rtc, info which can be used to improve the starup accuracy of the
> system from the rtc.

That's a non-issue for virtually all users.

> This is supported by both chrony and by the new (non-utils) hwclock.
> The 11 min mode completely destroys that.

Then disable the 11 minute mode if your application (i.e. the purpose
your computer is used for) requires it.

> It would be like instituting a procedure by which ntp polled the
> external sources and simply reset the clock each time it found an
> offset.

You're implying that there is some sort of mechanism to discipline the
RTC. As far as I know on a Linux system the RTC is read at start up,
periodically updated while the sytem is running and updated during the
shut down process.

Steve Kostecke <kostecke at ntp.org>
NTP Public Services Project - http://support.ntp.org/

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