1.\" $NetBSD: hardclock.9,v 1.3 2010/03/25 15:17:38 jruoho Exp $ 2.\" 3.\" Copyright (c) 2001 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Thomas Klausner. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd March 25, 2010 31.Dt HARDCLOCK 9 32.Os 33.Sh NAME 34.Nm hardclock 35.Nd real-time timer 36.Sh SYNOPSIS 37.Ft void 38.Fn hardclock "struct clockframe *frame" 39.Sh DESCRIPTION 40The 41.Fn hardclock 42function is called 43.Xr hz 9 44times per second. 45It implements the real-time system clock. 46The argument 47.Va frame 48is an opaque, 49machine-dependent structure that encapsulates the previous machine state. 50.Pp 51The 52.Fn hardclock 53performs different tasks such as: 54.Bl -bullet -offset indent 55.It 56Run the current process's virtual and profile time (decrease the 57corresponding timers, if they are activated, and generate 58.Li SIGVTALRM 59or 60.Li SIGPROF , 61respectively). 62.It 63Increment the time-of-day, taking care of any 64.Xr ntpd 8 65or 66.Xr adjtime 2 67induced changes and leap seconds, as well as any necessary 68compensations to keep in sync with PPS signals or external clocks, if 69support for this is in the kernel (see 70.Xr options 4 ) . 71.It 72Schedule softclock interrupts if any callouts should be triggered (see 73.Xr callout 9 ) . 74.El 75.Sh SEE ALSO 76.Xr adjtime 2 , 77.Xr ntp_adjtime 2 , 78.Xr signal 7 , 79.Xr ntpd 8 , 80.Xr callout 9 , 81.Xr hz 9 82