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Diffstat (limited to 'man2/adjtimex.2')
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diff --git a/man2/adjtimex.2 b/man2/adjtimex.2 new file mode 100644 index 000000000..7ed06118c --- /dev/null +++ b/man2/adjtimex.2 @@ -0,0 +1,146 @@ +.\" Hey Emacs! This file is -*- nroff -*- source. +.\" +.\" Copyright (c) 1995 Michael Chastain (mec@shell.portal.com), 15 April 1995. +.\" +.\" 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, write to the Free +.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, +.\" USA. +.\" +.\" 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 <mtk16@ext.canterbury.ac.nz> +.\" +.TH ADJTIMEX 2 2004-05-27 "Linux 2.6.6" "Linux Programmer's Manual" +.SH NAME +adjtimex \- tune kernel clock +.SH SYNOPSIS +.B #include <sys/timex.h> +.sp +.BI "int adjtimex(struct timex *" "buf" ); +.SH DESCRIPTION +Linux uses David L. Mills' clock adjustment algorithm (see RFC 1305). +The system call +.B 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 +.RS +.nf +struct timex { + int modes; /* mode selector */ + long offset; /* time offset (usec) */ + long freq; /* frequency offset (scaled ppm) */ + long maxerror; /* maximum error (usec) */ + long esterror; /* estimated error (usec) */ + int status; /* clock command/status */ + long constant; /* pll time constant */ + long precision; /* clock precision (usec) (read only) */ + long tolerance; /* clock frequency tolerance (ppm) + (read only) */ + struct timeval time; /* current time (read only) */ + long tick; /* usecs between clock ticks */ +}; +.fi +.RE +.PP +The +.I modes +field determines which parameters, if any, to set. +It may contain a +.RI bitwise- or +combination of zero or more of the following bits: +.PP +.RS +.nf +#define ADJ_OFFSET 0x0001 /* time offset */ +#define ADJ_FREQUENCY 0x0002 /* frequency offset */ +#define ADJ_MAXERROR 0x0004 /* maximum time error */ +#define ADJ_ESTERROR 0x0008 /* estimated time error */ +#define ADJ_STATUS 0x0010 /* clock status */ +#define ADJ_TIMECONST 0x0020 /* pll time constant */ +#define ADJ_TICK 0x4000 /* tick value */ +#define ADJ_OFFSET_SINGLESHOT 0x8001 /* old-fashioned adjtime */ +.fi +.RE +.PP +Ordinary users are restricted to a zero value for +.IR mode . +Only the superuser may set any parameters. +.br +.ne 12v +.SH "RETURN VALUE" +On success, +.B adjtimex +returns the clock state: +.PP +.RS +.nf +#define TIME_OK 0 /* clock synchronized */ +#define TIME_INS 1 /* insert leap second */ +#define TIME_DEL 2 /* delete leap second */ +#define TIME_OOP 3 /* leap second in progress */ +#define TIME_WAIT 4 /* leap second has occurred */ +#define TIME_BAD 5 /* clock not synchronized */ +.fi +.RE +.PP +On failure, +.B 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 is 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.mode +is non-zero and the caller does not have sufficient privilege. +Under Linux the +.B CAP_SYS_TIME +capability is required. +.SH "CONFORMING TO" +\fBadjtimex\fP is Linux specific and should not be used in programs +intended to be portable. There is a similar but less general call +\fBadjtime\fR in SVr4. +.SH "SEE ALSO" +.BR settimeofday (2), +.BR capabilities (7) |