[ntp:questions] How to get shared memory access from gpsd to ntpd to work?

Miroslav Lichvar mlichvar at redhat.com
Thu Aug 17 05:11:02 UTC 2017

On Wed, Aug 16, 2017 at 01:52:44PM +0100, Etaoin Shrdlu wrote:
> Hi all, 
> I've been battling for some time with getting ntpd to set the date/time
> from gpsd's shared memory locations. My GPS device is on the network
> and sends GPS messages every minute over UDP. This is picked up by gpsd
> and it appears I get a good fix with all the required data. It also
> looks as if the shared memory locations are being set up correctly. But
> whatever I do, ntpd time source "reach" stubbornly remains at zero,
> even when running ntpd as root. I would be most grateful if someone
> could cast their eyes on the configurations and log output below, and
> let me know if you can see were it's going wrong! 

There is a ntpshmmon program included with gpsd, which should show you
if gpsd is actually writing to the SHM segments and whether it's a
problem on the gpsd or ntpd side. However, I'm not sure if this is
supposed to work with GPS over network.

Miroslav Lichvar

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