Add a man page for the much referenced hardclock(9).

Thanks to niklas@, fgs@, mpech@ for feedback.

1 files changed, 78 insertions, 0 deletions

diff --git a/share/man/man9/hardclock.9 b/share/man/man9/hardclock.9
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+.\"	$OpenBSD: hardclock.9,v 1.1 2001/07/16 20:50:00 krw Exp $
+.\"
+.\" Copyright (c) 2001 Kenneth R Westerback
+.\" All rights reserved.
+.\"
+.\" 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,
+.\"    without modification, immediately at the beginning of the file.
+.\" 2. The name of the author may not be used to endorse or promote products
+.\"    derived from this software without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR OR HIS RELATIVES 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 MIND, 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 Jul 14, 2001
+.Dt HARDCLOCK 9
+.Os
+.Sh NAME
+.Nm hardclock
+.Nd real-time system clock
+.Sh SYNOPSIS
+.Fd #include <sys/systm.h>
+.Ft void
+.Fo "hardclock"
+.Fa "struct clockframe *frame"
+.Fc
+.Sh DESCRIPTION
+.Fn hardclock
+implements the the real-time system clock, interrupting
+.Xr hz 9
+times a second.
+The argument
+.Fa frame
+is an opaque, machine dependant structure that encapsulates the
+previous machine state.
+.Pp
+.Fn hardclock
+performs a variety of time related housekeeping tasks, such as
+.Bl -bullet -offset indent
+.It
+If the current process has virtual or profiling interval
+timers, update the timers and deliver appropriate signals.
+.It
+If there is no separate statistics clock, execute
+.Xr statclock 9 .
+.It
+Increment the time of day, implementing any adjustments requested by
+.Xr adjtime 2
+or required as a result of running a ntp daemon or other configured
+external clock.
+.It
+Update the real-time timeout queue, calling
+.Fn softclock
+directly if the current interrupt priority is low enough.
+.El
+.Sh SEE ALSO
+.Xr adjtime 2 ,
+.Xr hz 9 ,
+.Xr microtime 9 ,
+.Xr spl 9 ,
+.Xr time 9 ,
+.Xr timeout 9
+.Sh CODE REFERENCES
+.Fn hardclock
+is implemented in the file
+.Pa sys/kern/kern_clock.c .