On 8/26/2011 13:11, Rick Jones wrote:
A C<[email protected]> wrote:
Let me add that I'm using only the PPS_ATOM right now (GPS_NMEA is
not in the ntp.conf file at all) and the 64-ish bytes of binary data
is showing up at the serial port once per second.
However, even with a debug level of 10 I don't show anything being
written to the port.
If there is a user space process involved, a system call trace utility
can be a very good friend.
rick jones
Yeha, I've run ktrace on it before but it doesn't match what is being sent.
I ran it again and the PPS_ATOM driver is transmitting data at regular
intervals:
1327 1 ntpd 1314394905.210995629 CALL
ioctl(6,PPS_IOC_FETCH,0xefffe584)
1327 1 ntpd 1314394905.211100621 GIO fd 6 wrote 28 bytes
"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
1327 1 ntpd 1314394905.211273608 GIO fd 6 read 28 bytes
"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
1327 1 ntpd 1314394906.211064913 CALL
ioctl(6,PPS_IOC_FETCH,0xefffe584)
1327 1 ntpd 1314394906.211172905 GIO fd 6 wrote 28 bytes
"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
1327 1 ntpd 1314394906.211346891 GIO fd 6 read 28 bytes
"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
1327 1 ntpd 1314394907.226187042 GIO fd 6 wrote 28 bytes
"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
1327 1 ntpd 1314394907.226371028 GIO fd 6 read 28 bytes
"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
It's a string of nulls. But that doesn't match what shows up at the
port itself both in length and in data content. But the timing is
consistent (one write per second). Whatever is taking the write to the
file descriptor is then just bundling more data with it and shipping out
a 64 byte packet of data. 64 bytes just happens to be the length of a
NTP packet if you include the IP and UDP headers. I tried to manually
decode it but some fields weren't looking quite right.
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