watchdog(9)

NAME

watchdog - software and hardware watchdog facility

SYNOPSIS

#include <sys/watchdog.h>
void
watchdog_fn(void *private, u_int cmd, int *error);
EVENTHANDLER_REGISTER(watchdog_list,  watchdog_fn,  private,
0);

DESCRIPTION

To implement a watchdog in software or hardware, only a sin

gle function
needs to be written and registered on the global

watchdog_list.

The function must examine the cmd argument and act on it as

follows:

If cmd is zero, the watchdog must be disabled and the error

argument left
untouched.

Else the watchdog should be reset and configured to a time

out of (1 <<
(cmd & WD_INTERVAL)) nanoseconds or larger and the error ar

gument be set
to zero.

If the watchdog cannot be configured to the proposed time

out, it must be
disabled and the error argument left untouched.

There is no specification of what the watchdog should do

when it times
out, but a hardware reset or similar ``drastic but certain''

behaviour is
recommended.

SEE ALSO

watchdog(4)

AUTHORS

The watchdog facility and this manual page was written Poul

Henning Kamp
<phk@FreeBSD.org>.

BSD February 28, 2004

BSD