FreeBSD-5.3/share/man/man4/watchdog.4

.\" Copyright (c) 2004 Poul-Henning Kamp <phk@FreeBSD.org>
.\" Copyright (c) 2003, 2004 Sean M. Kelly <smkelly@FreeBSD.org>
.\" 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.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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 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.
.\"
.\" $FreeBSD: src/share/man/man4/watchdog.4,v 1.6 2004/06/19 21:17:07 smkelly Exp $
.\"
.Dd June 25, 2003
.Dt WATCHDOG 4
.Os
.Sh NAME
.Nm watchdog
.Nd "hardware and software watchdog"
.Sh SYNOPSIS
.Cd "options CPU_ELAN"
.Cd "options CPU_GEODE"
.Cd "options SW_WATCHDOG"
.Pp
.In sys/watchdog.h
.Sh DESCRIPTION
The
.Nm
facility is used for controlling hardware and software watchdogs.
.Pp
The interface is through a device named
.Qq Li /dev/
.Dv _PATH_WATCHDOG
which responds to a single
.Xr ioctl 2
call,
.Dv WDIOCPATPAT .
.Pp
The call takes a single argument which represents a timeout value
specified as an integer power of two nanoseconds.
.Pp
The
.Dv WD_ACTIVE
flag signals that the
.Nm
will be kept from
timing out from userland, for instance by the
.Xr watchdogd 8
daemon.
.Pp
To disable the watchdogs, an argument of zero should be used.
.Pp
The
.Xr ioctl 2
call will return success if just one of the available
.Xr watchdog 9
implementations support the request.
If the call fails, for instance if none of
.Xr watchdog 9
implementations support the timeout
length, all watchdogs are disabled and must be explicitly re-enabled.
.Sh EXAMPLES
.\" XXX insert some descriptive text here
.Bd -literal -offset indent
u_int u = WD_ACTIVE | WD_TO_8SEC;
int fd = open("/dev/" _PATH_WATCHDOG, O_RDWR);

ioctl(fd, WDIOCPATPAT, &u);
.Ed
.Sh SEE ALSO
.Xr watchdogd 8 ,
.Xr watchdog 9
.Sh HISTORY
The
.Nm
code first appeared in
.Fx 5.1 .
.Sh AUTHORS
.An -nosplit
The
.Nm
facility was written by
.An Poul-Henning Kamp Aq phk@FreeBSD.org .
The software watchdog code
and this manual page were written by
.An Sean Kelly Aq smkelly@FreeBSD.org .
Some contributions were made by
.An Jeff Roberson Aq jeff@FreeBSD.org .