[ntp:questions] Using ntpd with custom clock

unruh unruh at invalid.ca
Wed Oct 17 09:34:11 UTC 2012

On 2012-10-17, Rob <nomail at example.com> wrote:
> Kennedy, Paul <P.Kennedy at fugro.com.au> wrote:
>> Forgive me if I am wrong, but this is a very odd request.  As far as I
>> can tell, the request is for the NTP corrections to the system clock to
>> be used to correct a different clock.
>> I cannot quite understand how this is of practical use.  It is like
>> diagnosing the faults on your car engine and then applying the
>> corrections to a train engine.
> When it is an odd request in your opinion, it does not mean it is
> not valid.  It may explain why there is no standard code in ntpd
> to handle this situation, but it is no excuse to give wrong answers
> or boilerplate answers.
> It happens so often on this group.  There are two questions that
> very frequently pop up:
> - I want to test and validate how ntpd handles an unusual situation
>   (like a fault or a leap-second)
> - I want to keep an island of sytems synchronized to the same time
>   (but I don't care how that time relates to UTC)
> All the time we see those responses that declare the question as
> odd, or try to modify the requirements of the poster, or add a new
> piece of hardware (like a GPS receiver).
> And usually the responses are from the same small group of posters.
> It is really lame.   When you cannot answer the question, you can
> always keep quiet.  There is no need to always jump on the soapbox.

And since you did NOT give an answer to the poster, why did you not keep

As far as I know ntpd does not handle the sitution that the poster
apparently wants to handle. He will need to write code to use something
( the system clock, the output from a gps, the data from an ntp server)
to discipline his external hardware clock. If the clock allows its rate
to be changed, this should not be too hard. If it does not, it will be
more difficult. 

But we have no idea what the OP really wants. He has been very very
skimpy in telling us. 

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