DragonFly On-Line Manual Pages

NTP_ADJTIME(2)           DragonFly System Calls Manual          NTP_ADJTIME(2)

NAME
     ntp_adjtime -- NTP daemon application interface

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/types.h>
     #include <sys/timex.h>

     int
     ntp_adjtime(struct timex *tp);

DESCRIPTION
     The ntp_adjtime() system call is used as a kernel interface for Network
     Time Protocol daemons like dntpd(8) and ntpd(8).  Certain fields of the
     timex structure are interpreted in either microseconds or nanoseconds,
     according to the state of the STA_NANO bit in the status word.

     In the DragonFly kernel, the ntp_adjtime() and ntp_gettime(2) system
     calls can be used to determine which resolution is in use, and to select
     either one at any time.  The resolution selected affects the scaling of
     certain fields in the ntp_gettime() and ntp_adjtime() system calls.

     Take note that this API is extremely complex and stateful.  Users should
     not attempt modification without first reviewing the ntpd(8) sources in
     depth.

     /*
      * NTP daemon interface (ntp_adjtime()) - used to discipline CPU clock
      * oscillator and determine status.
      *
      * Note: The offset, precision and jitter members are in microseconds if
      * STA_NANO is zero and nanoseconds if not.
      */
     struct timex {
             unsigned int modes;     /* clock mode bits (wo) */
             long    offset;         /* time offset (ns/us) (rw) */
             long    freq;           /* frequency offset (scaled PPM) (rw) */
             long    maxerror;       /* maximum error (us) (rw) */
             long    esterror;       /* estimated error (us) (rw) */
             int     status;         /* clock status bits (rw) */
             long    constant;       /* poll interval (log2 s) (rw) */
             long    precision;      /* clock precision (ns/us) (ro) */
             long    tolerance;      /* clock frequency tolerance (scaled
                                      * PPM) (ro) */
             /*
              * The following read-only structure members are implemented
              * only if the PPS signal discipline is configured in the
              * kernel. They are included in all configurations to insure
              * portability.
              */
             long    ppsfreq;        /* PPS frequency (scaled PPM) (ro) */
             long    jitter;         /* PPS jitter (ns/us) (ro) */
             int     shift;          /* interval duration (s) (shift) (ro) */
             long    stabil;         /* PPS stability (scaled PPM) (ro) */
             long    jitcnt;         /* jitter limit exceeded (ro) */
             long    calcnt;         /* calibration intervals (ro) */
             long    errcnt;         /* calibration errors (ro) */
             long    stbcnt;         /* stability limit exceeded (ro) */
     };

     Upon successful completion, ntp_adjtime() will fill the tp argument with
     the current clock state.

RETURN VALUES
     The ntp_adjtime() function returns the value 0 if successful; otherwise
     the value -1 is returned and the global variable errno is set to indicate
     the error.

     Possible states of the clock are:

     TIME_OK     Everything okay, no leap second warning.
     TIME_INS    insert leap second warning.
     TIME_DEL    delete leap second warning.
     TIME_OOP    Leap second in progress.
     TIME_WAIT   Leap second has occurred.
     TIME_ERROR  Clock not synchronized.

ERRORS
     The ntp_adjtime() system call may return EPERM if the caller does not
     have sufficient permissions.

SEE ALSO
     ntp_gettime(2), dntpd(8), ntpd(8) (net/openntpd)

AUTHORS
     This manual page was written by Tom Rhodes <trhodes@FreeBSD.org>.

DragonFly 3.5                   April 25, 2012                   DragonFly 3.5