[ntp:questions] flag3, enable pps, disable kernel - what do they actually do ....

John Pettitt jpp at cloudview.com
Thu Mar 9 20:24:47 UTC 2006

I'm searching for some documentation on the merits (or otherwise) of using the kernel pps code
(fudge flag 3) in the nmea and pps drivers.   I have a box running FreeBSD 5.4 that has a GPS18lvc
attached  to a serial port with PPS hooked to DCD and a TrueTime GPS clock PPS output hooked to it's
parallel port.

I was having clock hop issues and in order to get the tos mindist feature I upgraded to rc1 however
"enable pps" is no longer part of rc1 (where did it go?) so I'm not entirely clear on what settings
I should be using and what the merits of the various options are.

Can somebody point me at come discussion of:

"enable/disable kernel" why would I want to disable the kernel code?  What practical effect do this

"enable/disable pps" - where did it go and why is it not longer needed?  What did it actually do?

"fudge flag3 1" what are the merits of using / not using this flag?


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