[ntp:questions] How do I enable PLL in the Linux kernel?

David L. Mills mills at udel.edu
Wed May 28 19:17:19 UTC 2008


Anton,

See rfc2783 and header file timex.h.

Dave

Anton Persson A wrote:
> Hi,
> 
> the manual for the ntpdc program says the following about the "kerninfo"
> command:
> 
>   "Obtain and print kernel phase-lock loop operating parameters. This
> information
>    is available only if the kernel has been specially modified for a
> precision
>    timekeeping function."
> 
> The output I get from kerninfo is the following:
> 
> ntpdc> kern
> pll offset:           0 s
> pll frequency:        0.000 ppm
> maximum error:        0.414224 s
> estimated error:      1.6e-05 s
> status:               0040  unsync
> pll time constant:    4
> precision:            1e-06 s
> frequency tolerance:  512 ppm
> 
> My questions are:
>  * What does "0040 unsync" mean? 
>  * Does this inform me that my
>    kernel has NOT been "specially modified for
>    a precision timekeeping function."?
>  * How do I make sure the PLL is enabled?
>  * Does the PLL feature require special hardware?
> 
>    Best regards,
>        Anton Persson, Ericsson Sweden.




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