WBWD(4) FreeBSD Kernel Interfaces Manual WBWD(4)


wbwddevice driver for watchdog timer found on Winbond Super I/O chips


To compile this driver into the kernel, place the following line in your kernel configuration file:

device wbwd

Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):



The wbwd driver provides watchdog(4) support for the watchdog interrupt timer present on at least the following Winbond Super I/O chips:

  • 83627HF/F/HG/G Rev. G
  • 83627HF/F/HG/G Rev. J
  • 83627HF/F/HG/G Rev. UD-A
  • 83627DHG IC ver. 5


The wbwd driver provides the following options as sysctl(8) variables.
This variable allows to program the timer to a value independent on the one provided by the watchdog(4) framework while still relying on the regular updates from e.g. watchdogd(8). This is particularly useful if your system provides multiple watchdogs and you want them to fire in a special sequence to trigger an NMI after a shorter period than the reset timeout for example. The value set must not be lower than the sleep time of watchdogd(8). A value of 0 disables this feature and the timeout value provided by watchdog(4) will be used.
If set this sysctl will tell the driver to log its current state before and after the timer reset on each invocation from watchdog(9) to the kernel message buffer for debugging.
This read-only value gives the state of some registers on last update.

The wbwd driver also provides further sysctl options that are hidden by default. See the source code for more information.


The wbwd driver first appeared in FreeBSD 10.0.


This manual page was written by Bjoern A. Zeeb <bz@FreeBSD.org>.
December 28, 2012 FreeBSD