[LinuxPPS] Re: Measuring interrupt latency with NTP

[Rodolfo Giometti]

On Sun, Aug 13, 2006 at 05:05:10PM -0400, linux at horizon.com wrote:
> 
> I don't claim it's pretty, but see attached for the ATOM driver.  The
> comment above time_pps_findsource needs fixing.  I poked at the ripencc

What do you mean? Which comment are you talking about? :-o

> Note that the failure to define PPS_API_VERS_1 is, I think, be a violation
> of RFC2781, since that constant is described in the RFC, and it says
> 
> # 3.2 New data structures
> # 
> #    The data structure declarations and symbol definitions for this API
> #    will appear in the header file <sys/timepps.h>.  The header file MUST
> #    define all constants described in this specification, even if they
> #    are not supported by the implementation.

I don't agree. In the specification we can read:

   The pps_params_t data type is used to discover and modify parameters
   of a PPS source.  The data type includes a mode field, described in
   section 3.3.  It also includes an api_version field, a read-only
   value giving the version of the API.  Currently, the only defined
   value is:

      #define PPS_API_VERS_1  1

   This field is present to enable binary compatibility with future
   versions of the API.

Since LinuxPPS should be (hopefully) a future versions of the API I decided to
define:

      #define PPS_API_VERS_2  2

:)

> diff -r -u ntp-4.2.2+dfsg.2/configure.ac ntp-4.2.2+dfsg.2local/configure.ac
> --- ntp-4.2.2+dfsg.2/configure.ac	2006-08-13 16:51:05.000000000 -0400
> +++ ntp-4.2.2+dfsg.2local/configure.ac	2006-08-13 12:04:21.000000000 -0400
> @@ -430,7 +430,7 @@
>  # include <errno.h>
>  #endif
>  #include <sys/timepps.h>
> -#ifdef PPS_API_VERS_1
> +#ifdef PPS_API_VERS
>  yes
>  #endif
>  ], [AC_CHECK_HEADERS(sys/timepps.h, [], [],

This should be a sanity checks for version 1 of the API implementation...

> diff -r -u ntp-4.2.2+dfsg.2/ntpd/refclock_atom.c ntp-4.2.2+dfsg.2local/ntpd/refclock_atom.c
> --- ntp-4.2.2+dfsg.2/ntpd/refclock_atom.c	2006-06-06 16:16:48.000000000 -0400
> +++ ntp-4.2.2+dfsg.2local/ntpd/refclock_atom.c	2006-08-13 11:37:54.000000000 -0400
> @@ -155,6 +155,9 @@
>  	register struct ppsunit *up;
>  	char	device[80];
>  	int	mode;
> +#ifdef PPS_HAVE_FINDSOURCE
> +	char	id[80];	/* Source description */
> +#endif
>  #endif /* HAVE_PPSAPI */
> [snip] 

Thanks for the patch.

Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti at enneenne.com
Linux Device Driver                             giometti at gnudd.com
Embedded Systems                     		giometti at linux.it
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