[LinuxPPS] Occasionally ntpd stops receiving NMEA data

[Rodolfo Giometti]

On Mon, Jun 05, 2006 at 01:06:36AM -0500, Philip M. White wrote:
> 
> Looks like both, because NMEA stops scrolling in ntpd debug mode, and
> ntpd marks the GPS device as being completely unusable.  If PPS was

In this situation, using the procfs interface, the PPS signal is still
present?

> > ntpd thinks it did.
> > Please verify using the /proc interface.
> > # cat /proc/pps/00/assert
> > 1149486295.999996675 #478873
> > 
> > (repeat, do you the numbers change?)
> 
> Indeed, the numbers do NOT change.  The 'assert' node's data is:
> 1149484412.1091000 #135
> where #135 is one greater than the last visible number in `dmesg'.

This means that LinuxPPS doesn't receive PPS signal anymore.

If LinuxPPS stops receiving PPS signal or hangs for some reason it
should not stop the NTPD driver, it just returns the last PPS events
and the driver should check it signaling to the user.

To verify that the LinuxPPS interface doesn't hang the driver, please,
use the "strace" command on your ntpd process.

However keep in mind that difference between version 2.0.0 and 2.1.0
are just regarding the new procfs interface...

Another difference is about declared PPS_API_VERS... can you please
trying to replace defines:

   #define PPS_API_VERS_2         2       /* LinuxPPS proposal, dated 2006-05 */
   #define PPS_API_VERS           PPS_API_VERS_2

with:

   #define PPS_API_VERS_1         1       /* draft-05, dated 1999-08 */
   #define PPS_API_VERS           PPS_API_VERS_1

and then recompiling all code?

Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti at enneenne.com
Linux Device Driver                             giometti at gnudd.com
Embedded Systems                     		giometti at linux.it
UNIX programming                     phone:     +39 349 2432127
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