[ntp:questions] PPS on Linux status?

David L. Mills mills at udel.edu
Mon May 14 03:49:28 UTC 2007


Marten,

The full functionality for precision kernel and PPS is in Solaris, 
FreeBSD and Alpha Tru64 (kernel option). FreeBSD works best for me using 
the pps driver (kernel option), since no level converter is required and 
the DCD is not an issue.

The PPSKit is specific to Linux and an API for it is in no other system 
known to me. The full API for the systems mentioned above is defined in 
RFC-2783.

Martin Karsten wrote:

> My apologies if I am beating a dead horse, but I've spent several hours
> today searching for a definite answer to the subject line question.
> 
> The PPS part of the ntp documentation at one point refers to the PPSkit
> for Linux and at another point says "The FreeBSD, Linux and Solaris
> implementations can be used with the stock kernels provided with those
> systems;" about the ntp PPS driver.
> 
> I understand that a full-scale PPS "system" in the kernel (and the PPS
> api) may not be needed to get ntp working with PPS (e.g. that seems to
> be the case for Solaris), but at least some level of support is probably
> required from the kernel (in the serial driver)? Does the stock Linux
> kernel (e.g. any recent 2.6 variant) support PPS or do I have to use an
> extension such as PPSkit to use a PPS signal on Linux for ntpd?
> 
> I have a setup (server 127.127.20.0 GPS/PPS) for which on a FreeBSD
> machine, ntptime shows the PPSSIGNAL status bit, but not on Linux.
> 
> Any help would be greatly appreciated.
> 
> Thanks,
> Martin




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