[ntp:questions] Trouble with ntpd and gpsd

Miroslav Lichvar mlichvar at redhat.com
Mon Jul 10 10:08:35 UTC 2017

On 2017-07-03, Thomas Schweikle <tschweikle at gmail.com> wrote:
> # Other options you want to pass to gpsd

> Starting ntpd I'd awaited gpsd to be available, but "reach" keeps "0":
>  SHM(0)          .GPS.            0 l    -   16    0    0.000
> 0.000   0.000
>  SHM(1)          .UPPS.           0 l    -   16    0
> 0.000    0.000   0.000
> I've looked after rights on /dev/ttyACM0 and added ntp to dialout, but
> this shall not be neccessary, since ntpd uses to access
> port 2947 with its nmea-driver. I just didn't find anything helpful
> with google for my case. Anybody out there having an idea how to get
> the whole thing working? BTW: iptables are not active. SeLinux or
> apparmor are off too.

Have you seen the gpsd time service howto?

You might need to add -n to GPSD_OPTIONS. From your ipcs output it seems
both gpsd and ntpd are attached to the same SHM segments, so that should
not be a problem. It's either gpsd not writing anything there, or ntpd
rejecting the samples it gets. It would help to see output from the
ntpshmmon command. If you don't see any samples, try running gpsd from
command line with -D 9.

Miroslav Lichvar

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