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

juergen perlinger juergen.perlinger at t-online.de
Mon Aug 21 08:06:29 UTC 2017


On 08/16/2017 02:52 PM, 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! 

I didn't look to close, but there's an alternative using driver 46 and
the JSON API of GPSD. It's a bit easier to set up.

> 
> P.S. This has been cross-posted from gpsd-users at nongnu.org, where I
> failed to get any response to my query. 
> 
> 
> # syslog gpsd startup: 
> 
> Aug  6 19:28:16 computer gpsd[374]: gpsd:INFO: launching (Version 3.11)
> Aug  6 19:28:16 computer gpsd[374]: gpsd:INFO: listening on port gpsd
> Aug  6 19:28:16 computer gpsd[374]: gpsd:PROG: NTPD shmat(0,0,0) succeeded, segment 0
> Aug  6 19:28:16 computer gpsd[374]: gpsd:PROG: NTPD shmat(32769,0,0) succeeded, segment 1
> Aug  6 19:28:16 computer gpsd[374]: gpsd:PROG: NTPD shmat(65538,0,0) succeeded, segment 2
> Aug  6 19:28:16 computer gpsd[374]: gpsd:PROG: NTPD shmat(98307,0,0) succeeded, segment 3
> Aug  6 19:28:16 computer gpsd[374]: gpsd:PROG: successfully connected to the DBUS system bus
> Aug  6 19:28:16 computer gpsd[374]: gpsd:PROG: shmat() succeeded, segment 131076
> Aug  6 19:28:16 computer gpsd[374]: gpsd:PROG: shared-segment creation succeeded,
> Aug  6 19:28:16 computer gpsd[374]: gpsd:INFO: stashing device udp://192.168.13.100:10110 at slot 0
> Aug  6 19:28:16 computer gpsd[374]: gpsd:INFO: opening UDP feed at 192.168.13.100, port 10110.
> Aug  6 19:28:16 computer gpsd[374]: gpsd:ERROR: UDP device open error can't connect to host/port pair.
> Aug  6 19:28:16 computer gpsd[374]: gpsd:ERROR: initial GPS device udp://192.168.13.100:10110 open failed
> Aug  6 19:28:16 computer gpsd[374]: gpsd:INFO: running with effective group ID 20
> Aug  6 19:28:16 computer gpsd[374]: gpsd:INFO: running with effective user ID 110
> Aug  6 19:28:16 computer gpsd[374]: gpsd:INFO: startup at 2017-08-06T19:28:16.000Z (1502047696)
> 
> # syslog ntpd startup:
> 
> Aug  6 19:28:24 computer ntpd[609]: ntpd 4.2.6p5 at 1.2349-o Mon Jul 25 22:35:28 UTC 2016 (1)
> Aug  6 19:28:24 computer ntp[582]: Starting NTP server: ntpd.
> Aug  6 19:28:24 computer ntpd[652]: proto: precision = 0.781 usec
> Aug  6 19:28:24 computer ntpd[652]: Listen and drop on 0 v4wildcard 0.0.0.0 UDP 123
> Aug  6 19:28:24 computer systemd[1]: Started LSB: Start NTP daemon.
> Aug  6 19:28:25 computer ntpd[652]: Listen and drop on 1 v6wildcard :: UDP 123
> Aug  6 19:28:25 computer ntpd[652]: Listen normally on 2 lo 127.0.0.1 UDP 123
> Aug  6 19:28:25 computer ntpd[652]: Listen normally on 3 eth0 192.168.13.100 UDP 123
> Aug  6 19:28:25 computer ntpd[652]: Listen normally on 4 lo ::1 UDP 123
> Aug  6 19:28:25 computer ntpd[652]: Listen normally on 5 eth0 fe80::6a89:f1d3:7ec0:510 UDP 123
> Aug  6 19:28:25 computer ntpd[652]: peers refreshed
> Aug  6 19:28:25 computer ntpd[652]: Listening on routing socket on fd #22 for interface updates
> 
> # syslog gpsd sample: 
> 
> Aug  6 19:56:42 computer gpsd[374]: gpsd:IO: <= GPS: $GPGGA,185748.0,1234.567890,N,00012.345678,E,1,10,0.9,13.6,M,47.0,M,,*6B
> Aug  6 19:56:42 computer gpsd[374]: gpsd:PROG: GPGGA sentence timestamped 185748.00.
> Aug  6 19:56:42 computer gpsd[374]: gpsd:PROG: GPGGA starts a reporting cycle.
> Aug  6 19:56:42 computer gpsd[374]: gpsd:IO: <= GPS: $GPRMC,185748.0,A,1234.567890,N,00012.345678,E,0.0,,060817,0.0,E,A*2B
> Aug  6 19:56:42 computer gpsd[374]: gpsd:PROG: GPRMC sentence timestamped 185748.00.
> Aug  6 19:56:42 computer gpsd[374]: gpsd:PROG: GPRMC ends a reporting cycle.
> Aug  6 19:56:42 computer gpsd[374]: gpsd:IO: <= GPS: $GPVTG,,T,0.0,M,0.0,N,0.0,K,A*0D
> Aug  6 19:56:42 computer gpsd[374]: gpsd:IO: <= GPS: $GPGSA,A,2,01,03,06,09,11,17,19,22,23,31,,,1.2,0.9,0.8*31
> Aug  6 19:56:42 computer gpsd[374]: gpsd:PROG: GPGSA sets mode 2
> Aug  6 19:56:42 computer gpsd[374]: gpsd:IO: <= GPS: $GPGSV,4,1,13,01,31,136,41,03,67,068,35,06,32,303,31,09,34,202,41*78
> Aug  6 19:56:42 computer gpsd[374]: gpsd:PROG: Partial satellite data (1 of 4).
> Aug  6 19:56:42 computer gpsd[374]: gpsd:IO: <= GPS: $GPGSV,4,2,13,11,09,153,39,17,40,243,40,19,42,272,30,22,42,082,40*78
> Aug  6 19:56:42 computer gpsd[374]: gpsd:PROG: Partial satellite data (2 of 4).
> Aug  6 19:56:42 computer gpsd[374]: gpsd:IO: <= GPS: $GPGSV,4,3,13,23,61,174,46,31,19,047,36,12,04,329,,14,00,039,*76
> Aug  6 19:56:42 computer gpsd[374]: gpsd:PROG: Partial satellite data (3 of 4).
> Aug  6 19:56:42 computer gpsd[374]: gpsd:IO: <= GPS: $GPGSV,4,4,13,25,01,001,*4C
> 
> 
> # /etc/default/gpsd
> 
> START_DAEMON="true"
> USBAUTO="false"
> DEVICES="udp://192.168.13.100:10110"
> GPSD_OPTIONS="-n -D5"
> 
> 
> # ntpd.conf: 
> 
> GPS Serial data reference (NTP0)
> server 127.127.28.0 minpoll 4 maxpoll 4 prefer
> fudge 127.127.28.0 time1 0.0 refid GPS
> 
> GPS PPS reference (NTP1)
> server 127.127.28.1 minpoll 4 maxpoll 4 prefer
> fudge 127.127.28.1 refid PPS
> 
> 
> # ntpq -p                                                                                                                                         Sun Aug  6 19:48:25 2017
> 
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
>  SHM(0)          .GPS.            0 l    -   16    0    0.000    0.000   0.000
>  SHM(1)          .PPS.            0 l    -   16    0    0.000    0.000   0.000
> 
> 
> # cat /proc/sysvipc/shm                                                                                                                           Sun Aug  6 19:30:45 2017
> 
>        key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap
> 1314148400          0   600         80   374   652      2     0     0     0     0 1502047705          0 1502047696       4096          0
> 1314148401      32769   600         80   374   652      2     0     0     0     0 1502047705          0 1502047696       4096          0
> 1314148402      65538   666         80   374   374      1     0     0     0     0 1502047696          0 1502047696          0          0
> 1314148403      98307   666         80   374   374      1     0     0     0     0 1502047696          0 1502047696          0          0
> 1196446532     131076   666      31616   374   374      1     0     0     0     0 1502047696          0 1502047696          0          0
> 
> 
> # gpsmon:
> 
> tcp://localhost:2947          JSON slave driver>
> (83) {"class":"VERSION","release":"3.11","rev":"3.11-3","proto_major":3,"proto_minor":9}
> (125) {"class":"DEVICES","devices":[{"class":"DEVICE","path":"udp://192.168.13.100:10110","activated":"2017-08-06T19:31:50.526Z"}]}
> (122) {"class":"WATCH","enable":true,"json":false,"nmea":false,"raw":2,"scaled":false,"timing":false,"split24":false,"pps":true}
> 
> tcp://localhost:2947          NMEA0183>
> ┌──────────────────────────────────────────────────────────────────────────────┐
> │Time: 2017-08-06T18:33:45.000Z Lat:  12 34' 56.789" N Lon:   0 12' 34.567" E  │
> └───────────────────────────────── Cooked TPV ─────────────────────────────────┘
> ┌──────────────────────────────────────────────────────────────────────────────┐
> │ GPGGA GPRMC GPVTG GPGSA GPGSV                                                │
> └───────────────────────────────── Sentences ──────────────────────────────────┘
> ┌──────────────────┐┌────────────────────────────┐┌────────────────────────────┐
> │Ch PRN  Az El S/N ││Time:      183345.0         ││Time:      183345.0         │
> │ 0   1 130 42  35 ││Latitude:   1234.567890 N   ││Latitude:  1234.567890      │
> │ 1   3  52 78  40 ││Longitude:  00012.34567 E   ││Longitude: 00012.34567      │
> │ 2   9 201 22  40 ││Speed:     0.0              ││Altitude:  109.4            │
> │ 3  11 151 20  45 ││Course:                     ││Quality:   1   Sats: 10     │
> │ 4  17 257 46  25 ││Status:    A       FAA: A   ││HDOP:      0.9              │
> │ 5  19 288 41  34 ││MagVar:    0.0  E           ││Geoid:     47.0             │
> │ 6  22  77 52  39 │└─────────── RMC ────────────┘└─────────── GGA ────────────┘
> │ 7  23 180 50  38 │┌────────────────────────────┐┌────────────────────────────┐
> │ 8  31  59 19  26 ││Mode: A2 Sats:              ││UTC:           RMS:         │
> │ 9 120   0  0  35 ││DOP: H=0.9   V=0.8   P=1.2  ││MAJ:           MIN:         │
> │10  12 338  5   0 ││TOFF:  3535.132782450       ││ORI:           LAT:         │
> │11  14  39  9   0 ││PPS:                        ││LON:           ALT:         │
> └────── GSV ───────┘└──────── GSA + PPS ─────────┘└─────────── GST ────────────┘
> (83) {"class":"VERSION","release":"3.11","rev":"3.11-3","proto_major":3,"proto_minor":9}
> (125) {"class":"DEVICES","devices":[{"class":"DEVICE","path":"udp://192.168.13.100:10110","activated":"2017-08-06T19:31:50.526Z"}]}
> (122) {"class":"WATCH","enable":true,"json":false,"nmea":false,"raw":2,"scaled":false,"timing":false,"split24":false,"pps":true}
> (73) $GPGGA,183345.0,1234.567890,N,00012.345678,E,1,10,0.9,9.4,M,47.0,M,,*5D
> (71) $GPRMC,183345.0,A,1234.334342,N,00012.345678,E,0.0,,060817,0.0,E,A*24
> (34) $GPVTG,,T,0.0,M,0.0,N,0.0,K,A*0D
> (59) $GPGSA,A,2,01,03,06,09,11,17,19,22,23,31,,,1.2,0.9,0.8*31
> (70) $GPGSV,3,1,12,01,42,130,35,03,78,052,40,09,22,201,40,11,20,151,45*7C
> (70) $GPGSV,3,2,12,17,46,257,25,19,41,288,34,22,52,077,39,23,50,180,38*7B
> (61) $GPGSV,3,3,12,31,19,059,26,33,,,35,12,05,338,,14,09,039,*46
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