1.\" Copyright (c) 2004 Poul-Henning Kamp <phk@FreeBSD.org> 2.\" Copyright (c) 2003, 2004 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.\" $FreeBSD$ 27.\" 28.Dd June 25, 2003 29.Dt WATCHDOG 4 30.Os 31.Sh NAME 32.Nm watchdog 33.Nd "hardware and software watchdog" 34.Sh SYNOPSIS 35.Cd "options CPU_ELAN" 36.Cd "options CPU_GEODE" 37.Cd "options SW_WATCHDOG" 38.Pp 39.In sys/watchdog.h 40.Sh DESCRIPTION 41The 42.Nm 43facility is used for controlling hardware and software watchdogs. 44.Pp 45The interface is through a device named 46.Qq Li /dev/ 47.Dv _PATH_WATCHDOG 48which responds to a single 49.Xr ioctl 2 50call, 51.Dv WDIOCPATPAT . 52.Pp 53The call takes a single argument which represents a timeout value 54specified as an integer power of two nanoseconds. 55.Pp 56The 57.Dv WD_ACTIVE 58flag signals that the 59.Nm 60will be kept from 61timing out from userland, for instance by the 62.Xr watchdogd 8 63daemon. 64.Pp 65To disable the watchdogs, an argument of zero should be used. 66.Pp 67The 68.Xr ioctl 2 69call will return success if just one of the available 70.Xr watchdog 9 71implementations support the request. 72If the call fails, for instance if none of 73.Xr watchdog 9 74implementations support the timeout 75length, all watchdogs are disabled and must be explicitly re-enabled. 76.Sh EXAMPLES 77.\" XXX insert some descriptive text here 78.Bd -literal -offset indent 79u_int u = WD_ACTIVE | WD_TO_8SEC; 80int fd = open("/dev/" _PATH_WATCHDOG, O_RDWR); 81 82ioctl(fd, WDIOCPATPAT, &u); 83.Ed 84.Sh SEE ALSO 85.Xr watchdogd 8 , 86.Xr watchdog 9 87.Sh HISTORY 88The 89.Nm 90code first appeared in 91.Fx 5.1 . 92.Sh AUTHORS 93.An -nosplit 94The 95.Nm 96facility was written by 97.An Poul-Henning Kamp Aq phk@FreeBSD.org . 98The software watchdog code 99and this manual page were written by 100.An Sean Kelly Aq smkelly@FreeBSD.org . 101Some contributions were made by 102.An Jeff Roberson Aq jeff@FreeBSD.org . 103