[ntp:questions] Timing issue with Linux and kernel PPS?

Uwe Klein uwe at klein-habertwedt.de
Sat Nov 17 21:57:47 UTC 2012

David Taylor wrote:
> I'm seeing behaviour on rebooting a Raspberry Pi Linux system which is 
> stopping the PPS signal getting through to NTP.  It seems that the GPS 
> device does not emit any pulses on the PPS line for some time after it 
> has been powered up.  This I understand and it's the time taken for a 
> good enough lock to be acquired.
> However, it seems that if the PPS part of the kernel hasn't seen a 
> transition, it does not create the pps device at least until the first 
> transition is seen.  The delay seems to be some 133 seconds here:

> Does this seem possible, and how might it be fixed?



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