[ntp:questions] testing slew only mode (-x), not slewing correctly (linux sles10, ntpd v 4.1.1)

Richard B. Gilbert rgilbert88 at comcast.net
Fri Oct 23 21:58:08 UTC 2009


Unruh wrote:
> Brian Utterback <brian.utterback at sun.com> writes:
> 
>> David Woolley wrote:
> 
>>> NTP uses the software clock, which is typically less accurate than the 
>>> RTC.  The RTC only steps in when the machine is powered down or between 
>>> operating systems.
>>>
> 
>> The interaction between the OS kernel and the RTC is platform and OS 
>> dependent. You should not assume that the RTC plays no role while the 
>> system is running.
> 
> Interesting. On which platforms is rtc used in the normal timekeeping
> role?
> 
> 
>> Brian Utterback

On some hardware, the clock will be sustained by a battery while the 
machine is powered off.  In at least some Sun hardware, the battery is 
embedded in the chip that stores the hardware Ethernet address.  In 
other manufacturers machines a "coin cell"; e.g. type 2032 is used to 
maintain the clock.

A system with no other means of getting time can set its clock from the RTC.

Some systems may lack such hardware and will come up with some value 
that bears little or no relationship to the correct time.




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