What is timepps.h used for?

Hal Murray hmurray at megapathdsl.net
Sat Dec 24 07:44:17 UTC 2016

> ... and if you are not using gpsd ?

If you have PPS hardware, there are 3 approaches.

You can use GPSD.  It will use the kernel PPS capture if the kernel supports 
it.  If not, it will try user mode timing.  I think that is only available on 

You can use the PPS driver.  That requires timepps.h to build and a few 
kernel modules (or the equivalent option built into the kernel): pps_core and 

You can let the kernel do all the work.  That's flag3 on the PPS driver.  It 
works significantly better, but requires building your own kernel.  It needs 
the CONFIG_NTP_PPS option.  That needs not NoHZ and most distros ship kernels 
with NoHZ.

These are my opinions.  I hate spam.

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