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freebsd/share/man/man4/watchdog.4
2004-04-29 08:33:12 +00:00

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.\" Copyright (c) 2004 Poul-Henning Kamp <phk@FreeBSD.org>
.\" Copyright (c) 2003, 2004 Sean M. Kelly <smkelly@FreeBSD.org>
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.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
.Bd -literal
u_int u = WD_ACTIVE | WD_8SEC;
int fd = open("/dev/" _PATH_WATCHDOG, O_RDWR);
ioctl(fd, WDIOCPATPAT, &u);
.Ed
.Sh DESCRIPTION
.Nm
is a facility for controlling hardware and software watchdog facilities.
.Pp
The interface is through a device named "/dev/"
.Dv _PATH_WATCHDOG
which
responds to a single ioctl call,
.Dv WDIOCPATPAT .
.Pp
The ioctl call takes an argument which consists of a timeout value
specified as an integer power of two nanoseconds.
.Pp
The
.Dv WD_ACTIVE
flag signals that the watchdog will be kept from
timing out from userland, for instance by the
.Xr watchdogd 8
daemon.
.Pp
To disable the watchdogs, use an argument of zero.
.Pp
The ioctl call will return success if just one of the available
watchdog implementations support the request.
If the ioctl fails, for instance if no watchdog supports the timeout
length, all watchdogs are disabled and must be explicitly reenabled.
.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 watchdog
facility were written by
.An Poul-Henning Kamp Aq phk@FreeBSD.org .
.Pp
The
.Nm SW_WATCHDOG
code and manual page were written by
.An Sean Kelly Aq smkelly@FreeBSD.org .
Some contributions were made by
.An Jeff Roberson Aq jeff@FreeBSD.org .