netbsd man page for swwdog

SWWDOG(4)						   BSD Kernel Interfaces Manual 						 SWWDOG(4)

NAME
     swwdog -- software watchdog timer

SYNOPSIS
     pseudo-device swwdog

DESCRIPTION
     The swwdog driver provides a software watchdog timer that works with wdogctl(8).  If the timer expires, the system reboots if the boolean
     variable swwdog_reboot is true; otherwise, the system will panic.	swwdog_reboot is accessible as a sysctl(8) variable, hw.swwdog.reboot and
     defaults to false.

     The default period of swwdog is 60 seconds.

     As with other watchdog timers, the swwdog driver prevents a system from suspending when the watchdog is armed.

SEE ALSO
     sysctl(8), wdogctl(8)

HISTORY
     The swwdog driver was written by Steven M. Bellovin.

BUGS
     Only one watchdog timer can be active at any given time.  (Arguably, this is a bug in the watchdog timer framework.)  Therefore, only a sin-
     gle instance of the swwdog device can be created.

     Kernel tickle mode is useless with swwdog and arguably should be rejected, since both it and this driver rely on the same callout mechanism;
     if one is blocked, almost certainly the other is as well.

     The alarm option to wdogctl(8) isn't implemented.

BSD
								   June 8, 2011 							       BSD