RE: Using non-PPS receiver for ntpd?

[Stein, Josh]

My goof - I didn't realize ntpshmmon needed to be run as root, so when run 
properly, I get this output:


sudo ntpshmmon
ntpshmmon: version 3.22
#      Name  Seen@                 Clock                 Real                 L 
Prc
sample NTP0  1623073512.249175133  1623073512.249115134  1623255417.640000000 0 
-20
sample NTP0  1623073513.106892051  1623073513.106142732  1623255418.640000000 0 
-20
sample NTP0  1623073514.565437446  1623073514.565121718  1623255419.640000000 0 
-20
sample NTP0  1623073515.418676782  1623073515.417867828  1623255420.640000000 0 
-20
sample NTP0  1623073516.106361486  1623073516.106117373  1623255421.640000000 0 
-20
sample NTP0  1623073517.572209656  1623073517.571352473  1623255422.640000000 0 
-20
sample NTP0  1623073518.251686329  1623073518.250851072  1623255423.640000000 0 
-20
sample NTP0  1623073519.100469698  1623073519.100353084  1623255424.640000000 0 
-20
sample NTP0  1623073520.555216570  1623073520.555090893  1623255425.640000000 0 
-20
sample NTP0  1623073521.233966892  1623073521.233336687  1623255426.640000000 0 
-20
sample NTP0  1623073522.106322538  1623073522.105327387  1623255427.640000000 0 
-20
sample NTP0  1623073523.572438676  1623073523.571828470  1623255428.640000000 0 
-20
sample NTP0  1623073524.250163951  1623073524.250070618  1623255429.640000000 0 
-20
sample NTP0  1623073525.122916782  1623073525.122811314  1623255430.640000000 0 
-20
sample NTP0  1623073526.574967053  1623073526.574289140  1623255431.640000000 0 
-20
sample NTP0  1623073527.253089774  1623073527.252547537  1623255432.640000000 0 
-20
sample NTP0  1623073528.105942550  1623073528.105796093  1623255433.640000000 0 
-20


-----Original Message-----
From: Stein, Josh 
Sent: Wednesday, June 9, 2021 11:08 AM
To: Greg Troxel <gdt@lexort.com>
Cc: gpsd users <gpsd-users@nongnu.org>
Subject: RE: Using non-PPS receiver for ntpd?

It looks like a permissions issue is at the heart of this right now:

ntpshmmon
WARNING: could not open SHM(0): Permission denied(13)
WARNING: could not open SHM(1): Permission denied(13)
ntpshmmon: version 3.22
#      Name  Seen@                 Clock                 Real                 L 
Prc

I'll re-check who is running gpsd and ntpd to make sure it is indeed root and 
try again...




-----Original Message-----
From: Greg Troxel <gdt@lexort.com> 
Sent: Wednesday, June 9, 2021 10:48 AM
To: Stein, Josh <josh@anl.gov>
Cc: gpsd users <gpsd-users@nongnu.org>
Subject: Re: Using non-PPS receiver for ntpd?


"Stein, Josh" <josh@anl.gov> writes:

Run 'ntpshmon' and see if you are getting reports.

Restart ntpd after having started gpsd.  I'm not sure this is or should be 
necessary, but...

> But the output from ntpq doesn't look good to (my untrained) eye:
>
> ntpq -p
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
>  us.pool.ntp.org .POOL.          16 p    -   64    0    0.000    0.000   0.001
>  SHM(0)          .GPS.            0 l    -   64    0    0.000    0.000   0.000
>
> I'm currently focusing on the "pool" entry of the ntp.conf as a 
> possible culprit for my (apparent) problem. As you stated, this is not 
> a gpsd specific issue so that debugging path likely does not belong 
> here on this mailing list.

The pool entry is from default config, and tells ntpd to look up servers to use 
and add them.  With no internet, that won't work, but that should be ok.  That 
status line won't really change.

The problem is that ntpd is not seeing data from shared memory.