swwdog(4) - NetBSD Manual Pages

SWWDOG(4)               NetBSD Kernel Interfaces Manual              SWWDOG(4)


NAME

     swwdog -- software watchdog timer


SYNOPSIS

     pseudo-device swwdog [count]


DESCRIPTION

     The swwdog driver provides a software watchdog timer that works with
     wdogctl(8).  If the timer expires, the system reboots unless the variable
     swwdog_panic is non-zero; if it is, the system will panic instead.

     The default period of swwdog is 60 seconds.


SEE ALSO

     wdogctl(8)


HISTORY

     The swwdog driver was written by Steven M. Bellovin.


BUGS

     Although more than one swwdog timer can be configured, it's a pointless
     thing to do, since only one watchdog timer can be active at any given
     time.  Arguably, this is a bug in the watchdog timer framework.

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

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

NetBSD 3.0                      January 6, 2005                     NetBSD 3.0