[LinuxPPS] cross posting [time-nuts] NTP API on Linux 2.6.26

[Hal V. Engel]

On Sunday 11 January 2009 10:48:24 Folkert van Heusden wrote:
> > > Fedora's ntp rpm patches the makfiles like I posted for -lrt, does that
> > > have a similar effect?
>
> added that to my config as well
>
> > > > If you parse through the output from the configure you should see:
> > > > checking for clock_gettime... yes
> > > > checking for clock_settime... yes
>
> belle:/usr/local/src/ntp-4.2.4p6# grep -i clock_.ettime config.log | sort
> -u ac_cv_func_clock_gettime=yes
> ac_cv_func_clock_settime=yes
> configure:43363: checking for clock_gettime
> configure:43363: checking for clock_settime
> configure:48512: checking if we'll use clock_settime or settimeofday or
> stime configure:48534: result: clock_settime()
>
> | #define HAVE_CLOCK_GETTIME 1
>
> #define HAVE_CLOCK_GETTIME 1
>
> | #define HAVE_CLOCK_SETTIME 1
>
> #define HAVE_CLOCK_SETTIME 1
>
> So I got them too I guess.
>
> > http://sourceware.org/ml/libc-alpha/2008-03/msg00076.html ?  Without this
> > or the ntp patch that Michael Meier posted to the list yesterday
> > http://www.mulder.franken.de/blogfiles/timex.h ntp will only be capable
> > to doing microsecond timing.
>
> Added that to my CFLAGS:
> CFLAGS="$CFLAGS -I/usr/local/src/timex.h -I/lib/modules/`uname
> -r`/build/include -I/lib/modules/`uname -r`/build/Documentation/pps
> -DHAVE_PPSAPI" LDFLAGS=-lrt ./configure --prefix=/usr/local/ntp
> --disable-all-clocks --disable-parse-clocks --enable-NMEA
> --enable-LOCAL-CLOCK
>
> (I first created a directory /usr/local/src/timex.h and then put the
> timex.h in it)
>
> > When I run ntptime I get:
> > # ntptime
> > ntp_gettime() returns code 0 (OK)
> >   time cd137e25.947b02a0  Sat, Jan 10 2009 12:05:57.580, (.580002806),
> >   maximum error 8294508 us, estimated error 2 us, TAI offset 0
> > ntp_adjtime() returns code 0 (OK)
> >   modes 0x0 (),
> >   offset -0.426 us, frequency -39.298 ppm, interval 1 s,
> >   maximum error 8294508 us, estimated error 2 us,
> >   status 0x2001 (PLL,NANO),
> >   time constant 4, precision 0.001 us, tolerance 500 ppm,
>
> Odd. I still get:
>
> belle:/usr/local/src/ntp-4.2.4p6# /usr/local/ntp/bin/ntptime
> ntp_gettime() returns code 5 (ERROR)
>   time cd14bd4c.3240a000  Sun, Jan 11 2009 19:47:40.196, (.196299),
>   maximum error 9016 us, estimated error 16 us
> ntp_adjtime() returns code 5 (ERROR)
>   modes 0x0 (),
>   offset -26.000 us, frequency -3.138 ppm, interval 1 s,
>   maximum error 9016 us, estimated error 16 us,
>   status 0x40 (UNSYNC),
>   time constant 4, precision 1.000 us, tolerance 500 ppm,

Ntp is not synced yet.  Until ntp has SYNCed ntptime will report precision = 
1.000 us even if ntp is capable of NANO mode.  Either your refclock is not yet 
working or you didn't wait long enough to run this.  It is also possible that 
you are not picking up the correct timex.h file during the build. You need to 
have a look at the config log to confirm which file is used.

Hal