watchdog.4 revision 116874
1 2.\" Copyright (c) 2003 Sean M. Kelly <smkelly@FreeBSD.org> 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD: head/share/man/man4/watchdog.4 116874 2003-06-26 09:50:52Z smkelly $ 27.\" 28.Dd June 25, 2003 29.Dt WATCHDOG 4 30.Os 31.Sh NAME 32.Nm watchdog 33.Nd Software watchdog 34.Sh SYNOPSIS 35.Cd options WATCHDOG 36.Sh DESCRIPTION 37.Nm 38is a set of checks and routines which allow the implementation of a software 39watchdog solution. 40.Pp 41The user interface for 42.Nm 43is implemented via a trio of sysctl OIDs. 44When 45.Li debug.watchdog.enabled 46is set to a positive value, 47.Nm 48timeout checks are performed. 49In order to keep the watchdog from triggering, 50.Li debug.watchdog.reset 51must be accessed, 52by reading or writing, 53within every 54.Li debug.watchdog.timeout 55seconds. 56Failure to keep the 57.Nm 58updated will result in the kernel outputting interrupt counts, 59backtraces, 60and then attempting to enter 61.Xr ddb 9 . 62.Sh SEE ALSO 63.Xr sysctl 8 , 64.Xr watchdogd 8 65.Sh HISTORY 66The 67.Nm 68code first appeared in 69.Fx 5.1 . 70.Sh AUTHORS 71.An -nosplit 72The 73.Nm 74code and manual page were written by 75.An Sean Kelly Aq smkelly@FreeBSD.org . 76Some contributions were made by 77.An Jeff Roberson Aq jeff@FreeBSD.org . 78