[ntp:questions] Re: Linux 2.6 + PPS + ntpd?

Ulrich Windl Ulrich.Windl at RZ.Uni-Regensburg.DE
Fri Jan 20 13:05:44 UTC 2006


hmurray at suespammers.org (Hal Murray) writes:

> >2.4 vanilla kernels plus Ulrich' PPSkit-patches are easy to get
> >  going. Not tried 2.6 myself. But do you need the kernel PPSAPI? ntpd
> >  can do that outside the kernel as well. Sorry my only pps
> >  signal going to a Linux machine is using above 2.4-nano kernel.
> 
> There are two parts to the PPSAPI.  One is capturing the time
> the PPS signal changes so user code (ntpd) can analyze it.
> The other is including (one version of) that analysis in the
> kenel to discipline the system clock.
> 
> I think the PPSKit for 2.4 included both parts and the 2.6 version
> does not include the clock discipline code.

Correct! As said before: Linux 2.6 still has the old NTP kernel code. As long
as there is no nanosecond clock for Linux 2.6, you'll have to wait. (I had
implemented a new nanosecond clock for Linux 2.4, but it never made it into
the mainstream kernel. I won't do that again, but let the others (who know
better) do it).

For 2.6 you only get the PPS API's essential parts (plus the parallel port
support).

Regards,
Ulrich




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