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 mechanism; if one is blocked, almost certainly the other is as well.

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