151 lines
4.4 KiB
Groff
151 lines
4.4 KiB
Groff
.\"
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.\" Copyright (c) 2003 Tom Rhodes
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd April 1, 2003
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.Dt NTP_ADJTIME 2
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.Os
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.Sh NAME
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.Nm ntp_adjtime
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.Nd NTP daemon application interface
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.Sh SYNOPSIS
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.In sys/types.h
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.In sys/timex.h
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.Ft int
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.Fn ntp_adjtime "struct timex *tp"
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.Sh DESCRIPTION
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The
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.Fn ntp_adjtime
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system call is used as a kernel interface
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for the Network Time Protocol daemon,
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.Xr ntpd 8 .
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Certain fields of the
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.Vt timex
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structure are interpreted in either
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microseconds or nanoseconds, according to the state of the
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.Dv STA_NANO
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bit in the
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.Va status
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word.
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.Pp
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In the
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.Fx
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kernel, the
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.Fn ntp_adjtime
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and
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.Xr ntp_gettime 2
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system calls can be used to determine which
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resolution is in use, and to select either one at any time.
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The resolution selected affects the scaling of certain fields in the
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.Fn ntp_gettime
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and
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.Fn ntp_adjtime
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system calls.
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.Pp
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Take note that this
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.Tn API
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is extremely complex and stateful.
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Users should not attempt modification without first
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reviewing the
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.Xr ntpd 8
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sources in depth.
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.Bd -literal
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/*
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* NTP daemon interface (ntp_adjtime()) - used to discipline CPU clock
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* oscillator and determine status.
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*
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* Note: The offset, precision and jitter members are in microseconds if
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* STA_NANO is zero and nanoseconds if not.
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*/
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struct timex {
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unsigned int modes; /* clock mode bits (wo) */
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long offset; /* time offset (ns/us) (rw) */
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long freq; /* frequency offset (scaled PPM) (rw) */
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long maxerror; /* maximum error (us) (rw) */
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long esterror; /* estimated error (us) (rw) */
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int status; /* clock status bits (rw) */
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long constant; /* poll interval (log2 s) (rw) */
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long precision; /* clock precision (ns/us) (ro) */
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long tolerance; /* clock frequency tolerance (scaled
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* PPM) (ro) */
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/*
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* The following read-only structure members are implemented
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* only if the PPS signal discipline is configured in the
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* kernel. They are included in all configurations to insure
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* portability.
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*/
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long ppsfreq; /* PPS frequency (scaled PPM) (ro) */
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long jitter; /* PPS jitter (ns/us) (ro) */
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int shift; /* interval duration (s) (shift) (ro) */
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long stabil; /* PPS stability (scaled PPM) (ro) */
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long jitcnt; /* jitter limit exceeded (ro) */
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long calcnt; /* calibration intervals (ro) */
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long errcnt; /* calibration errors (ro) */
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long stbcnt; /* stability limit exceeded (ro) */
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};
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.Ed
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.Pp
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Upon successful completion,
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.Fn ntp_adjtime
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will fill the
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.Fa tp
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argument with the current clock state.
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.Sh RETURN VALUES
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Upon successful completion the clock state is returned.
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Otherwise a -1 is returned and the global variable
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.Va errno
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is set to indicate the error.
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.Pp
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Possible states of the clock are:
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.Pp
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.Bl -tag -compact -width ".Dv TIME_ERROR"
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.It Dv TIME_OK
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Everything okay, no leap second warning.
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.It Dv TIME_INS
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insert leap second warning.
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.It Dv TIME_DEL
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delete leap second warning.
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.It Dv TIME_OOP
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Leap second in progress.
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.It Dv TIME_WAIT
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Leap second has occurred.
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.It Dv TIME_ERROR
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Clock not synchronized.
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.El
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.Sh ERRORS
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The
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.Fn ntp_adjtime
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system call may return
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.Er EPERM
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if the caller
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does not have sufficient permissions.
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.Sh SEE ALSO
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.Xr ntp_gettime 2 ,
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.Xr ntpd 8
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.Sh AUTHORS
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This manual page was written by
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.An Tom Rhodes Aq trhodes@FreeBSD.org .
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