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WATCHDOG(4)              BSD Kernel Interfaces Manual              WATCHDOG(4)

NAME
     watchdog -- hardware and software watchdog

SYNOPSIS
     options CPU_ELAN
     options CPU_GEODE
     options SW_WATCHDOG

     #include <&lt;sys/watchdog.h>&gt;

DESCRIPTION
     The watchdog facility is used for controlling hardware and software
     watchdogs.

     The interface is through a device named "/dev/" _PATH_WATCHDOG which
     responds to a single ioctl(2) call, WDIOCPATPAT.

     The call takes a single argument which represents a timeout value speci-
     fied as an integer power of two nanoseconds.

     The WD_ACTIVE flag signals that the watchdog will be kept from timing out
     from userland, for instance by the watchdogd(8) daemon.

     To disable the watchdogs, an argument of zero should be used.

     The ioctl(2) call will return success if just one of the available
     watchdog(9) implementations support the request.  If the call fails, for
     instance if none of watchdog(9) implementations support the timeout
     length, all watchdogs are disabled and must be explicitly re-enabled.

EXAMPLES
           u_int u = WD_ACTIVE | WD_TO_8SEC;
           int fd = open("/dev/" _PATH_WATCHDOG, O_RDWR);

           ioctl(fd, WDIOCPATPAT, &u);

SEE ALSO
     watchdogd(8), watchdog(9)

HISTORY
     The watchdog code first appeared in FreeBSD 5.1.

AUTHORS
     The watchdog facility was written by Poul-Henning Kamp <phkATFreeBSD.org>.
     The software watchdog code and this manual page were written by Sean
     Kelly <smkellyATFreeBSD.org>.  Some contributions were made by Jeff
     Roberson <jeffATFreeBSD.org>.

BSD                              June 25, 2003                             BSD