diff options
| author | Eric S. Raymond <esr@thyrsus.com> | 2013-10-17 07:09:53 -0400 |
|---|---|---|
| committer | Eric S. Raymond <esr@thyrsus.com> | 2013-10-17 07:09:53 -0400 |
| commit | 838f38f224c4a6601b25ce62ceb5c3b7c25d3201 (patch) | |
| tree | e51317ba7587fdfbda21719c07d31da9dd8b778f /ntpshm.c | |
| parent | dc201907f3bebfafc3f3eedee518a7a601da4b7d (diff) | |
| download | gpsd-838f38f224c4a6601b25ce62ceb5c3b7c25d3201.tar.gz | |
Some clarifying comment.
Diffstat (limited to 'ntpshm.c')
| -rw-r--r-- | ntpshm.c | 8 |
1 files changed, 7 insertions, 1 deletions
@@ -3,6 +3,12 @@ * struct shmTime and getShmTime from file in the xntp distribution: * sht.c - Testprogram for shared memory refclock * + * Yes, this file is something of a swamp. It helps to know that there are + * two PPS delivery methods in play. One, kernel PPS (KPPS), is a Linux-only + * feature supplied through special /dev/pps devices. The other, serial PPS, + * uses the TIOCMIWAIT ioctl to explicitly watch for PPS on serial lines. KPPS + * requires roor permissions; serial PPS does not. + * * This file is Copyright (c) 2010 by the GPSD project * BSD terms apply: see the file COPYING in the distribution root for details. */ @@ -394,7 +400,7 @@ static int ntpshm_pps(struct gps_device_t *session, struct timeval *tv) * code will work, but it's not a SuS/POSIX standard header. We're * going to include it unconditionally here because we expect both * Linux and BSD to have it and we want compilation to break with - * an audible snapping sound. + * an audible snapping sound if it's not present. */ #include <sys/ioctl.h> |