"Tim" <[EMAIL PROTECTED]> writes:
> Hi,
> in the ntp faq, it's written:
> "Does my Operating System have the Kernel Discipline?
> To make sure, try using the ntp_gettime() system call."
>
> Fist, I made this test on a machine... and I have the system call
> ntp_gettime(). So I think I have the kernel discipline. It's confirmed
> in the /var/log/ntp.log file with the line:
> kernel time sync enabled.
> I also tried the command ntptime which gives:
> ntp_gettime() returns code 0 (OK)
> time c7f9adc5.296ee000 Wed, Apr 26 2006 10:28:53.161, (.161848),
> maximum error 274450 us, estimated error 10661 us
> ntp_adjtime() returns code 0 (OK)
> modes 0x0 (),
> offset 1755.000 us, frequency -3.955 ppm, interval 4 s,
> maximum error 274450 us, estimated error 10661 us,
> status 0x1 (PLL),
> time constant 4, precision 1.000 us, tolerance 512 ppm,
> pps frequency 0.000 ppm, stability 512.000 ppm, jitter 200.000 us,
> intervals 0, jitter exceeded 0, stability exceeded 0, errors 0.
>
> So everything seems to be OK. I dont use a PPS source so PPS values are
> normal. And I use the kernel discipline with a PLL. Am I right?
Yes, so far.
>
>
> Now, I want to check that the kernel discipline on my embedded product.
> It's based on a Power PC CPU... I do exactly the same test.
> ntp_gettime() system call works fine. But when i check my ntp.log,
> there is always the line:
> ntp sync disabled... and I don't know why. Also if I do ntptime, here
> is the output:
>
> ntp_gettime() returns code 5 (ERROR)
"ERROR" mean what it says.
> time c7f9aeee.336f6000 Wed, Apr 26 2006 8:33:50.200, (.200918),
> maximum error 227078 us, estimated error 3816 us
> ntp_adjtime() returns code 5 (ERROR)
> modes 0x0 (),
> offset 2899.000 us, frequency 162.167 ppm, interval 4 s,
> maximum error 227078 us, estimated error 3816 us,
> status 0x1 (PLL),
> time constant 0, precision 1.000 us, tolerance 512 ppm,
> pps frequency 0.000 ppm, stability 512.000 ppm, jitter
> 200.000 us,
> intervals 0, jitter exceeded 0, stability exceeded 0,
> errors 0.
> So why Have I return code 5 ERROR? and if the kernel discipline
> enabled? I think that yes because the status is PLL but i'm not sure...
I can only guess that the implementation of ntp_gettime() is wrong.
The patch in my PPSkit for Linux may be a bit paranoid, but maybe compare your
code with this one:
+ if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0
+ /* clock not synchronized (hardware or software error) */
+#ifdef CONFIG_NTP_PPS
|| ((time_status & (STA_PPSFREQ|STA_PPSTIME)) != 0
&& (time_status & STA_PPSSIGNAL) == 0)
- /* p. 24, (b) */
+ /* PPS signal lost when either PPS time or PPS frequency
+ * synchronization requested
+ */
|| ((time_status & (STA_PPSTIME|STA_PPSJITTER))
== (STA_PPSTIME|STA_PPSJITTER))
- /* p. 24, (c) */
+ /* PPS jitter exceeded when PPS time synchronization requested */
|| ((time_status & STA_PPSFREQ) != 0
- && (time_status & (STA_PPSWANDER|STA_PPSERROR)) != 0))
- /* p. 24, (d) */
+ && (time_status & (STA_PPSWANDER|STA_PPSERROR)) != 0)
+ /* PPS wander exceeded or calibration error when PPS frequency
+ * synchronization requested
+ */
+#endif
+ )
Regards,
Ulrich
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