NMEA but no PPS in ntp, Ubuntu 18.04.5

[Steve Bourland]

Yo gang!
  So I am (again) struggling with getting NTPd and GPSd talking super well with
each other.  I've just build gpsd-3.21, hopefully here is enough information for
someone to point me in the right direction:

# ./gpsd -V
gpsd: 3.21 (revision 3.21)


# ./gpsd -D 3 -N -b -n /dev/ttyS0
gpsd:INFO: launching (Version 3.21)
gpsd:INFO: listening on port gpsd
gpsd:INFO: stashing device /dev/ttyS0 at slot 0
gpsd:INFO: SER: opening read-only GPS data source type 2 and at '/dev/ttyS0'
gpsd:INFO: SER: speed 4800, 8N1
gpsd:INFO: SER: speed 9600, 8O1
gpsd:INFO: SER: speed 4800, 8N1
gpsd:INFO: SER: speed 9600, 8N1
gpsd:INFO: SER: speed 4800, 8N1
gpsd:INFO: gpsd_activate(2): activated GPS (fd 5)
gpsd:INFO: KPPS:/dev/ttyS0 RFC2783 path:/dev/pps0, fd is 6
gpsd:INFO: KPPS:/dev/ttyS0 pps_caps 0x1133
gpsd:INFO: KPPS:/dev/ttyS0 have PPS_CANWAIT
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS will be used
gpsd:INFO: PPS:/dev/ttyS0 ntpshm_link_activate: 1
gpsd:INFO: device /dev/ttyS0 activated
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout unknown error
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout unknown error
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout unknown error
gpsd:INFO: running with effective group ID 20
gpsd:INFO: running with effective user ID 65534
gpsd:INFO: startup at 2020-11-17T18:00:34.000Z (1605636034)
gpsd:INFO: /dev/ttyS0 identified as type NMEA0183, 0 sec @ 4800bps
gpsd:WARN: WARNING: WKRO bug: leap second 18 inconsistent with 986320834,
corrected to 1605636034 (2020-11-17T18:00:34.000Z)
gpsd:INFO: Sats used (0):
gpsd:WARN: WARNING: WKRO bug: leap second 18 inconsistent with 986320835,
corrected to 1605636035 (2020-11-17T18:00:35.000Z)
gpsd:INFO: PPS:/dev/ttyS0 Assert hooks called clock:  1605636036.000715640 real:
1605636036.000000000: no fix
gpsd:INFO: Sats used (0):
gpsd:WARN: WARNING: WKRO bug: leap second 18 inconsistent with 986320836,
corrected to 1605636036 (2020-11-17T18:00:36.000Z)
gpsd:INFO: PPS:/dev/ttyS0 Assert hooks called clock:  1605636037.000715367 real:
1605636037.000000000: no fix


# ppstest /dev/pps0
trying PPS source "/dev/pps0"
found PPS source "/dev/pps0"
ok, found 1 source(s), now start fetching data...
source 0 - assert 1606773054.001145830, sequence: 2484 - clear 
1606773053.221156408, sequence: 2483
source 0 - assert 1606773054.001145830, sequence: 2484 - clear 
1606773054.221147010, sequence: 2484
source 0 - assert 1606773055.001140425, sequence: 2485 - clear 
1606773054.221147010, sequence: 2484
source 0 - assert 1606773055.001140425, sequence: 2485 - clear 
1606773055.221149354, sequence: 2485
source 0 - assert 1606773056.001163846, sequence: 2486 - clear 
1606773055.221149354, sequence: 2485
source 0 - assert 1606773056.001163846, sequence: 2486 - clear 
1606773056.221153897, sequence: 2486
source 0 - assert 1606773057.001163535, sequence: 2487 - clear 
1606773056.221153897, sequence: 2486
source 0 - assert 1606773057.001163535, sequence: 2487 - clear 
1606773057.221147729, sequence: 2487
source 0 - assert 1606773058.001180197, sequence: 2488 - clear 
1606773057.221147729, sequence: 2487
source 0 - assert 1606773058.001180197, sequence: 2488 - clear 
1606773058.221150275, sequence: 2488



% ntpd --version
ntpd 4.2.8p10@1.3728-o (1)

% ntpq -pn
     remote           refid      st t when poll reach   delay   offset jitter
==============================================================================
 127.127.28.0    .NMEA.           0 l    3   16  377    0.000  -258.02 9.660
 127.127.28.1    .PPS.            0 l    -   16    0    0.000    0.000 0.000


So ntp sees the NMEA, but not the PPS (the ppstest data is from today, the 
rest of the data from my previous attempt to ask for help).  This is a 
server that was running "just fine" until the rollover firmware error came 
along (it's a Garmin 18 LVC, yes, I know, ancient and a POS, but it has 
served me well for a long time).  I have some other servers that have 
manifest the same problem moving from Ubuntu 16.04 to 18.04.  Back before 
the gpsd-3.20 release, I was able to get a machine running with version 
3.19.1~dev (revision 3.19.1~dev-2019-12-16T16:01:12), it is still running 
just fine.  Does anyone have any suggestions on where I am mis-stepping?
                                        Thanks,
                                          Steve