296 lines
8.8 KiB
Groff
296 lines
8.8 KiB
Groff
.\" $NetBSD: ntp_adjtime.2,v 1.2 2001/09/07 23:46:03 wiz Exp $
|
|
.\"
|
|
.\" Copyright (c) 2001 The NetBSD Foundation, Inc.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to The NetBSD Foundation
|
|
.\" by Thomas Klausner.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the NetBSD
|
|
.\" Foundation, Inc. and its contributors.
|
|
.\" 4. Neither the name of The NetBSD Foundation nor the names of its
|
|
.\" contributors may be used to endorse or promote products derived
|
|
.\" from this software without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
|
|
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
|
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
|
|
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
.\" POSSIBILITY OF SUCH DAMAGE.
|
|
.\"
|
|
.Dd September 4, 2001
|
|
.Dt NTP_ADJTIME 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm ntp_adjtime ,
|
|
.Nm ntp_gettime
|
|
.Nd Network Time Protocol (NTP) daemon interface system calls
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.Fd #include <sys/timex.h>
|
|
.Ft int
|
|
.Fn ntp_adjtime "struct timex *"
|
|
.Ft int
|
|
.Fn ntp_gettime "struct ntptimeval *"
|
|
.Sh DESCRIPTION
|
|
The two system calls
|
|
.Fn ntp_adjtime
|
|
and
|
|
.Fn ntp_gettime
|
|
are the kernel interface to the Network Time Protocol (NTP) daemon
|
|
.Xr ntpd 8 .
|
|
.Pp
|
|
The
|
|
.Fn ntp_adjtime
|
|
function is used by the NTP daemon to adjust the system clock to an
|
|
externally derived time. The time offset and related variables which
|
|
are set by
|
|
.Fn ntp_adjtime
|
|
are used by
|
|
.Xr hardclock 9
|
|
to adjust the phase and frequency of the phase- or frequency-lock loop
|
|
(PLL resp. FLL) which controls the system clock.
|
|
.Pp
|
|
The
|
|
.Fn ntp_gettime
|
|
function provides the time, maximum error (sync distance) and
|
|
estimated error (dispersion) to client user application programs.
|
|
.Pp
|
|
In the following, all variables that refer PPS are only relevant if
|
|
the
|
|
.Em PPS_SYNC
|
|
option (see
|
|
.Xr options 4 )
|
|
is enabled in the kernel.
|
|
.Pp
|
|
.Fn ntp_adjtime
|
|
has as argument a
|
|
.Va struct timex *
|
|
of the following form:
|
|
.Bd -literal
|
|
struct timex {
|
|
unsigned int modes; /* clock mode bits (wo) */
|
|
long offset; /* time offset (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; /* pll time constant (rw) */
|
|
long precision; /* clock precision (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.
|
|
*/
|
|
long ppsfreq; /* pps frequency (scaled ppm) (ro) */
|
|
long jitter; /* pps jitter (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) */
|
|
};
|
|
.Ed
|
|
.Pp
|
|
The members of this struct have the following meanings when used as
|
|
argument for
|
|
.Fn ntp_adjtime :
|
|
.Bl -tag -width tolerance -compact
|
|
.It Fa modes
|
|
Defines what settings should be changed with the current
|
|
.Fn ntp_adjtime
|
|
call (write-only). Bitwise OR of the following:
|
|
.Bl -tag -width MOD_TIMECONST -compact -offset indent
|
|
.It MOD_OFFSET
|
|
set time offset
|
|
.It MOD_FREQUENCY
|
|
set frequency offset
|
|
.It MOD_MAXERROR
|
|
set maximum time error
|
|
.It MOD_ESTERROR
|
|
set estimated time error
|
|
.It MOD_STATUS
|
|
set clock status bits
|
|
.It MOD_TIMECONST
|
|
set PLL time constant
|
|
.It MOD_CLKA
|
|
set clock A
|
|
.It MOD_CLKB
|
|
set clock B
|
|
.El
|
|
.It Fa offset
|
|
Time offset (in microseconds), used by the PLL/FLL to adjust the
|
|
system time in small increments (read-write).
|
|
.It Fa freq
|
|
Frequency offset (scaled ppm) (read-write).
|
|
.It Fa maxerror
|
|
Maximum error (in microseconds). Initialized by an
|
|
.Fn ntp_adjtime
|
|
call, and increased by the kernel once each second to reflect the maximum
|
|
error bound growth (read-write).
|
|
.It Fa esterror
|
|
Estimated error (in microseconds). Set and read by
|
|
.Fn ntp_adjtime ,
|
|
but unused by the kernel (read-write).
|
|
.It Fa status
|
|
System clock status bits (read-write). Bitwise OR of the following:
|
|
.Bl -tag -width STA_PPSJITTER -compact -offset indent
|
|
.It STA_PLL
|
|
Enable PLL updates (read-write).
|
|
.It STA_PPSFREQ
|
|
Enable PPS freq discipline (read-write).
|
|
.It STA_PPSTIME
|
|
Enable PPS time discipline (read-write).
|
|
.It STA_FLL
|
|
Select frequency-lock mode (read-write).
|
|
.It STA_INS
|
|
Insert leap (read-write).
|
|
.It STA_DEL
|
|
Delete leap (read-write).
|
|
.It STA_UNSYNC
|
|
Clock unsynchronized (read-write).
|
|
.It STA_FREQHOLD
|
|
Hold frequency (read-write).
|
|
.It STA_PPSSIGNAL
|
|
PPS signal present (read-only).
|
|
.It STA_PPSJITTER
|
|
PPS signal jitter exceeded (read-only).
|
|
.It STA_PPSWANDER
|
|
PPS signal wander exceeded (read-only).
|
|
.It STA_PPSERROR
|
|
PPS signal calibration error (read-only).
|
|
.It STA_CLOCKERR
|
|
Clock hardware fault (read-only).
|
|
.El
|
|
.It Fa constant
|
|
PLL time constant, determines the bandwidth, or
|
|
.Dq stiffness ,
|
|
of the PLL (read-write).
|
|
.It Fa precision
|
|
Clock precision (in microseconds). In most cases the same
|
|
as the kernel tick variable (see
|
|
.Xr hz 9 ) .
|
|
If a precision clock counter or external time-keeping signal is available,
|
|
it could be much lower (and depend on the state of the signal)
|
|
(read-only).
|
|
.It Fa tolerance
|
|
Maximum frequency error, or tolerance of the CPU clock oscillator (scaled
|
|
ppm). Ordinarily a property of the architecture, but could change under
|
|
the influence of external time-keeping signals (read-only).
|
|
.It Fa ppsfreq
|
|
PPS frequency offset produced by the frequency median filter (scaled
|
|
ppm) (read-only).
|
|
.It Fa jitter
|
|
PPS jitter measured by the time median filter in microseconds
|
|
(read-only).
|
|
.It Fa shift
|
|
Logarithm to base 2 of the interval duration in seconds (PPS,
|
|
read-only).
|
|
.It Fa stabil
|
|
PPS stability (scaled ppm); dispersion (wander) measured by the
|
|
frequency median filter (read-only).
|
|
.It Fa jitcnt
|
|
Number of seconds that have been discarded because the jitter measured
|
|
by the time median filter exceeded the limit
|
|
.Em MAXTIME
|
|
(PPS, read-only).
|
|
.It Fa calcnt
|
|
Count of calibration intervals (PPS, read-only).
|
|
.It Fa errcnt
|
|
Number of calibration intervals that have been discarded because the
|
|
wander exceeded the limit
|
|
.Em MAXFREQ
|
|
or where the calibration interval jitter exceeded two ticks (PPS,
|
|
read-only).
|
|
.It Fa stbcnt
|
|
Number of calibration intervals that have been discarded because the
|
|
frequency wander exceeded the limit
|
|
.Em MAXFREQ Ns /4
|
|
(PPS, read-only).
|
|
.El
|
|
After the
|
|
.Fn ntp_adjtime
|
|
call, the
|
|
.Va struct timex *
|
|
structure contains the current values of the corresponding variables.
|
|
.Pp
|
|
.Fn ntp_gettime
|
|
has as argument a
|
|
.Va struct ntptimeval *
|
|
with the following members:
|
|
.Bd -literal
|
|
struct ntptimeval {
|
|
struct timeval time; /* current time (ro) */
|
|
long maxerror; /* maximum error (us) (ro) */
|
|
long esterror; /* estimated error (us) (ro) */
|
|
};
|
|
.Ed
|
|
.Pp
|
|
These have the following meaning:
|
|
.Bl -tag -width tolerance -compact
|
|
.It Fa time
|
|
Current time (read-only).
|
|
.It Fa maxerror
|
|
Maximum error in microseconds (read-only).
|
|
.It Fa esterror
|
|
Estimated error in microseconds (read-only).
|
|
.El
|
|
.Sh RETURN VALUES
|
|
.Fn ntp_adjtime
|
|
and
|
|
.Fn ntp_gettime
|
|
return the current state of the clock on success, or any of the errors
|
|
of
|
|
.Xr copyin 9
|
|
and
|
|
.Xr copyout 9 .
|
|
.Fn ntp_adjtime
|
|
may additionally return
|
|
.Er EPERM
|
|
if the user calling
|
|
.Fn ntp_adjtime
|
|
does not have sufficient permissions.
|
|
.Pp
|
|
Possible states of the clock are:
|
|
.Bl -tag -width TIME_ERROR -compact -offset indent
|
|
.It TIME_OK
|
|
Everything okay, no leap second warning.
|
|
.It TIME_INS
|
|
.Dq insert leap second
|
|
warning.
|
|
.It TIME_DEL
|
|
.Dq delete leap second
|
|
warning.
|
|
.It TIME_OOP
|
|
Leap second in progress.
|
|
.It TIME_WAIT
|
|
Leap second has occurred.
|
|
.It TIME_ERROR
|
|
Clock not synchronized.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr options 4 ,
|
|
.Xr ntpd 8 ,
|
|
.Xr hardclock 9 ,
|
|
.Xr hz 9
|