[LinuxPPS] setting an offset

[James Boddington]

Bernhard Schiffner wrote:
> If I read the code right, the static offset is something local to ntpd.
> refclock_atom.c about line 409: "SAMPLE(dtemp + pp->fudgetime1);"
> 
> Means ntpd adds some value to the pps-readout.
> 
> The interrupt (DCD-signal) is only shifted if the hardware of a pps-source 
> is (can be) configured properly.
> 
> Nice test if fudge1 accepts ns (for cable delay compensation).
> Hopefully (>50) µs for real shifting.
> 

I tried fudge 127.127.20.0 time 0.0000005 and the offset for that reference 
changed by 500ns (+/- jitter). Was watching peerstats.

> I didn't test it.
> 
> IMHO there is no need for linuxpps to have an offset inside.
> 

The pps rfc says PPS_OFFSETASSERT and PPS_OFFSETCLEAR are optional but were 
still implemented.

What about when it is something other than ntp that is using the time stamp? 
While I have the kernel using the time stamp directly this is of interest to me.

-- 
    James