[ntp:questions] ntpd connect gpsd shared memory driver

Richard Cagley rcagley at gmail.com
Tue Jun 18 18:15:48 UTC 2013


On Tue, Jun 18, 2013 at 11:06 AM, A C <agcarver+ntp at acarver.net> wrote:

> I suspect you may have a conflict between the kernel attempting to control
> PPS and gpsd attempting to use it.  Try adding "disable kernel" to the
> ntp.conf to shut off the kernel's use of PPS and see if that wakes up gpsd.
>  If so, your serial driver doesn't want to play nice and share the DCD line
> between two processes.


Yeah, I agree. This definitely seems like the problem. I have pps support
built into the kernel. Should I remove that support? It's slightly
confusing to me who "controls" the pps line as there are several actors in
play here...gpsd, ntpd, the kernel.

With the new entry "disable kernel" in ntpd.conf...
---
server 127.127.28.0 minpoll 4 maxpoll 4
fudge 127.127.28.0 time1 0.420 refid GPS
server 127.127.28.1 minpoll 4 maxpoll 4 prefer
fudge 127.127.28.1 refid GPS1
server clock.redhat.com
server 0.us.pool.ntp.org
server 1.us.pool.ntp.org
server 2.us.pool.ntp.org
server 3.us.pool.ntp.org
disable kernel
---
I get this after about 5 min...
---
/ # ntpq -p
     remote           refid      st t when poll reach   delay   offset
 jitter
==============================================================================
*SHM(0)          .GPS.            0 l   14   16  177    0.000   20.062
 12.250
 SHM(1)          .GPS1.           0 l    -   16    0    0.000    0.000
0.000
 clock1.redhat.c .CDMA.           1 u   56   64    3   81.138  -165.16
 14.327
 vimo.dorui.net  198.82.1.203     3 u   56   64    3   81.730  -166.40
 14.743
 soft-sjc-01.ser 64.250.229.100   2 u   56   64    3   12.289  -165.71
 10.420
 199.4.29.166    64.113.32.5      2 u   56   64    3   74.375  -162.43
 11.199
 66-162-15-65.li 64.236.96.53     2 u   59   64    3   64.446  -159.15
 10.202
---


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