+++ /dev/null
-.\" Copyright (c) 1995 Michael Chastain (mec@shell.portal.com), 15 April 1995.
-.\" and Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
-.\"
-.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
-.\" This is free documentation; you can redistribute it and/or
-.\" modify it under the terms of the GNU General Public License as
-.\" published by the Free Software Foundation; either version 2 of
-.\" the License, or (at your option) any later version.
-.\"
-.\" The GNU General Public License's references to "object code"
-.\" and "executables" are to be interpreted as the output of any
-.\" document formatting or typesetting system, including
-.\" intermediate and printed output.
-.\"
-.\" This manual is distributed in the hope that it will be useful,
-.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
-.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-.\" GNU General Public License for more details.
-.\"
-.\" You should have received a copy of the GNU General Public
-.\" License along with this manual; if not, see
-.\" <http://www.gnu.org/licenses/>.
-.\" %%%LICENSE_END
-.\"
-.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
-.\" Modified 1997-07-30 by Paul Slootman <paul@wurtel.demon.nl>
-.\" Modified 2004-05-27 by Michael Kerrisk <mtk.manpages@gmail.com>
-.\"
-.TH ADJTIMEX 2 2014-12-31 "Linux" "Linux Programmer's Manual"
-.SH NAME
-adjtimex \- tune kernel clock
-.SH SYNOPSIS
-.nf
-.BR "#define _BSD_SOURCE" " /* See feature_test_macros(7) */"
-.B #include <sys/timex.h>
-
-.BI "int adjtimex(struct timex *" "buf" );
-.fi
-.SH DESCRIPTION
-Linux uses David L. Mills' clock adjustment algorithm (see RFC\ 5905).
-The system call
-.BR adjtimex ()
-reads and optionally sets adjustment parameters for this algorithm.
-It takes a pointer to a
-.I timex
-structure, updates kernel parameters from field values,
-and returns the same structure with current kernel values.
-This structure is declared as follows:
-.PP
-.in +4n
-.nf
-struct timex {
- int modes; /* Mode selector */
- long offset; /* Time offset; nanoseconds, if STA_NANO
- status flag is set, otherwise microseconds */
- long freq; /* Frequency offset, in units of 2^-16 ppm
- (parts per million, see NOTES below) */
- long maxerror; /* Maximum error (microseconds) */
- long esterror; /* Estimated error (microseconds) */
- int status; /* Clock command/status */
- long constant; /* PLL (phase-locked loop) time constant */
- long precision; /* Clock precision (microseconds, read-only) */
- long tolerance; /* Clock frequency tolerance (ppm, read-only) */
- struct timeval time;
- /* Current time (read-only, except for
- ADJ_SETOFFSET); upon return, time.tv_usec
- contains nanoseconds, if STA_NANO status
- flag is set, otherwise microseconds */
- long tick; /* Microseconds between clock ticks */
- long ppsfreq; /* PPS (pulse per second) frequency (in units
- of 2^-16 ppm\-\-see NOTES, read-only) */
- long jitter; /* PPS jitter (read-only); nanoseconds, if
- STA_NANO status flag is set, otherwise
- microseconds */
- int shift; /* PPS interval duration (seconds, read-only) */
- long stabil; /* PPS stability (2^-16 ppm\-\-see NOTES,
- read-only) */
- long jitcnt; /* PPS jitter limit exceeded (read-only) */
- long calcnt; /* PPS calibration intervals (read-only) */
- long errcnt; /* PPS calibration errors (read-only) */
- long stbcnt; /* PPS stability limit exceeded (read-only) */
- int tai; /* TAI offset, as set by previous ADJ_TAI
- operation (seconds, read-only,
- since Linux 2.6.26) */
- /* Further padding bytes to allow for future expansion */
-};
-.fi
-.in
-.PP
-The
-.I modes
-field determines which parameters, if any, to set.
-It is a bit mask containing a
-.RI bitwise- or
-combination of zero or more of the following bits:
-.TP
-.BR ADJ_OFFSET
-Set time offset from
-.IR buf.offset .
-.TP
-.BR ADJ_FREQUENCY
-Set frequency offset from
-.IR buf.freq .
-.TP
-.BR ADJ_MAXERROR
-Set maximum time error from
-.IR buf.maxerror .
-.TP
-.BR ADJ_ESTERROR
-Set estimated time error from
-.IR buf.esterror .
-.TP
-.BR ADJ_STATUS
-Set clock status from
-.IR buf.status .
-.TP
-.BR ADJ_TIMECONST
-Set PLL time constant from
-.IR buf.constant .
-If the
-.B STA_NANO
-status flag (see below) is clear, the kernel adds 4 to this value.
-.TP
-.BR ADJ_SETOFFSET " (since Linux 2.6.29)"
-.\" commit 094aa1881fdc1b8889b442eb3511b31f3ec2b762
-.\" Author: Richard Cochran <richardcochran@gmail.com>
-Add
-.I buf.time
-to the current time.
-If
-.I buf.status
-includes the
-.B ADJ_NANO
-flag, then
-.I buf.time.tv_usec
-is interpreted as a nanosecond value;
-otherwise it is interpreted as microseconds.
-.TP
-.BR ADJ_MICRO " (since Linux 2.6.36)"
-.\" commit eea83d896e318bda54be2d2770d2c5d6668d11db
-.\" Author: Roman Zippel <zippel@linux-m68k.org>
-Select microsecond resolution.
-.TP
-.BR ADJ_NANO " (since Linux 2.6.36)"
-.\" commit eea83d896e318bda54be2d2770d2c5d6668d11db
-.\" Author: Roman Zippel <zippel@linux-m68k.org>
-Select nanosecond resolution.
-Only one of
-.BR ADJ_MICRO
-and
-.BR ADJ_NANO
-should be specified.
-.TP
-.BR ADJ_TAI " (since Linux 2.6.26)"
-.\" commit 153b5d054ac2d98ea0d86504884326b6777f683d
-Set TAI (Atomic International Time) offset from
-.IR buf->constant .
-
-.BR ADJ_TAI
-should not be used in conjunction with
-.BR ADJ_TIMECONST ,
-since the latter mode also employs the
-.IR buf->constant
-field.
-
-For a complete explanation of TAI
-and the difference between TAI and UTC, see
-.UR http://www.bipm.org/en/bipm/tai/tai.html
-.I BIPM
-.UE
-.TP
-.BR ADJ_TICK
-Set tick value from
-.IR buf.tick .
-.PP
-Alternatively,
-.I modes
-can be specified as either of the following (multibit mask) values,
-in which case other bits should not be specified in
-.IR modes :
-.\" In general, the other bits are ignored, but ADJ_OFFSET_SINGLESHOT 0x8001
-.\" ORed with ADJ_NANO (0x2000) gives 0xa0001 == ADJ_OFFSET_SS_READ!!
-.TP
-.BR ADJ_OFFSET_SINGLESHOT
-.\" In user space, ADJ_OFFSET_SINGLESHOT is 0x8001
-.\" In kernel space it is 0x0001, and must be ANDed with ADJ_ADJTIME (0x8000)
-Old-fashioned
-.BR adjtime ():
-(gradually) adjust time by value specified in
-.IR buf.offset ,
-which specifies an adjustment in microseconds.
-.TP
-.BR ADJ_OFFSET_SS_READ " (functional since Linux 2.6.28)"
-.\" In user space, ADJ_OFFSET_SS_READ is 0xa001
-.\" In kernel space there is ADJ_OFFSET_READONLY (0x2000) anded with
-.\" ADJ_ADJTIME (0x8000) and ADJ_OFFSET_SINGLESHOT (0x0001) to give 0xa001)
-Return (in
-.IR buf.offset )
-the remaining amount of time to be adjusted after an earlier
-.BR ADJ_OFFSET_SINGLESHOT
-operation.
-This feature was added in Linux 2.6.24,
-.\" commit 52bfb36050c8529d9031d2c2513b281a360922ec
-but did not work correctly
-.\" commit 916c7a855174e3b53d182b97a26b2e27a29726a1
-until Linux 2.6.28.
-.PP
-Ordinary users are restricted to a value of either 0 or
-.B ADJ_OFFSET_SS_READ
-for
-.IR modes .
-Only the superuser may set any parameters.
-
-The
-.I buf.status
-field is a bit mask that is used to set and/or retrieve status
-bits associated with the NTP implementation.
-Some bits in the mask are both readable and settable,
-while others are read-only.
-.TP
-.BR STA_PLL
-Enable phase-locked loop (PLL) updates (read-write) via
-.BR ADJ_OFFSET .
-.TP
-.BR STA_PPSFREQ
-Enable PPS freq discipline (read-write).
-.TP
-.BR STA_PPSTIME
-Enable PPS time discipline (read-write).
-.TP
-.BR STA_FLL
-Select frequency-locked loop (FLL) mode (read-write).
-.TP
-.BR STA_INS
-Insert leap second (read-write).
-.TP
-.BR STA_DEL
-Delete leap second (read-write).
-.TP
-.BR STA_UNSYNC
-Clock unsynchronized (read-write).
-.TP
-.BR STA_FREQHOLD
-Hold frequency (read-write).
-.TP
-.BR STA_PPSSIGNAL
-PPS signal present (read-only).
-.TP
-.BR STA_PPSJITTER
-PPS signal jitter exceeded (read-only).
-.TP
-.BR STA_PPSWANDER
-PPS signal wander exceeded (read-only).
-.TP
-.BR STA_PPSERROR
-PPS signal calibration error (read-only).
-.TP
-.BR STA_CLOCKERR
-Clock hardware fault (read-only).
-.TP
-.BR STA_NANO " (since Linux 2.6.26)"
-.\" commit eea83d896e318bda54be2d2770d2c5d6668d11db
-.\" Author: Roman Zippel <zippel@linux-m68k.org>
-Resolution (0 = microsecond, 1 = nanoseconds; read-only).
-Set via
-.BR ADJ_NANO ,
-cleared via
-.BR ADJ_MICRO .
-.TP
-.BR STA_MODE " (since Linux 2.6.26)"
-.\" commit eea83d896e318bda54be2d2770d2c5d6668d11db
-.\" Author: Roman Zippel <zippel@linux-m68k.org>
-Mode (0 = Phase Locked Loop, 1 = Frequency Locked Loop; read-only).
-.TP
-.BR STA_CLK " (since Linux 2.6.26)"
-.\" commit eea83d896e318bda54be2d2770d2c5d6668d11db
-.\" Author: Roman Zippel <zippel@linux-m68k.org>
-Clock source (0 = A, 1 = B; read-only).
-.\" FIXME It would be helpful to have some explanation of what
-.\" "Clock source" is.
-.PP
-Attempts to set read-only
-.I status
-bits are silently ignored.
-.SH RETURN VALUE
-On success,
-.BR adjtimex ()
-returns the clock state; that is, one of the following values:
-.TP 12
-.BR TIME_OK
-Clock synchronized.
-.TP
-.BR TIME_INS
-Insert leap second.
-.TP
-.BR TIME_DEL
-Delete leap second.
-.TP
-.BR TIME_OOP
-Leap second in progress.
-.TP
-.BR TIME_WAIT
-Leap second has occurred.
-.TP
-.BR TIME_ERROR
-Clock not synchronized.
-The symbolic name
-.B TIME_BAD
-is a synonym for
-.BR TIME_ERROR ,
-provided for backward compatibility.
-.PP
-On failure,
-.BR adjtimex ()
-returns \-1 and sets
-.IR errno .
-.SH ERRORS
-.TP
-.B EFAULT
-.I buf
-does not point to writable memory.
-.TP
-.B EINVAL
-An attempt was made to set
-.I buf.offset
-to a value outside the range \-131071 to +131071,
-or to set
-.I buf.status
-to a value other than those listed above,
-or to set
-.I buf.tick
-to a value outside the range
-.RB 900000/ HZ
-to
-.RB 1100000/ HZ ,
-where
-.B HZ
-is the system timer interrupt frequency.
-.TP
-.B EPERM
-.I buf.modes
-is neither 0 nor
-.BR ADJ_OFFSET_SS_READ ,
-and the caller does not have sufficient privilege.
-Under Linux, the
-.B CAP_SYS_TIME
-capability is required.
-.SH NOTES
-In struct
-.IR timex ,
-.IR freq ,
-.IR ppsfreq ,
-and
-.I stabil
-are ppm (parts per million) with a 16-bit fractional part,
-which means that a value of 1 in one of those fields
-actually means 2^-16 ppm, and 2^16=65536 is 1 ppm.
-This is the case for both input values (in the case of
-.IR freq )
-and output values.
-.SH CONFORMING TO
-.BR adjtimex ()
-is Linux-specific and should not be used in programs
-intended to be portable.
-See
-.BR adjtime (3)
-for a more portable, but less flexible,
-method of adjusting the system clock.
-.SH SEE ALSO
-.BR settimeofday (2),
-.BR adjtime (3),
-.BR capabilities (7),
-.BR time (7),
-.BR adjtimex (8)
-.SH COLOPHON
-This page is part of release 3.79 of the Linux
-.I man-pages
-project.
-A description of the project,
-information about reporting bugs,
-and the latest version of this page,
-can be found at
-\%http://www.kernel.org/doc/man\-pages/.
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