January 6, 2005 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.