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     wbwd — device driver for Winbond/Nuvoton Super I/O chips watchdog timer


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

           device superio
           device wbwd

     Alternatively, to load the driver as a module at boot time, place the following line in



     The wbwd driver provides watchdog(4) support for the watchdog interrupt timer present on at
     least the following Super I/O chips:
        Winbond 83627HF/F/HG/G
        Winbond 83627S
        Winbond 83697HF
        Winbond 83697UG
        Winbond 83637HF
        Winbond 83627THF
        Winbond 83687THF
        Winbond 83627EHF
        Winbond 83627DHG
        Winbond 83627UHG
        Winbond 83667HG
        Winbond 83627DHG-P
        Winbond 83667HG-B
        Nuvoton NCT6775
        Nuvoton NCT6776
        Nuvoton NCT6102
        Nuvoton NCT6779
        Nuvoton NCT6791
        Nuvoton NCT6792


     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

             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.


     superio(4) watchdog(4), device.hints(5), watchdog(8), watchdogd(8), watchdog(9)


     The wbwd driver first appeared in FreeBSD 10.0.


     This manual page was written by Bjoern A. Zeeb <>.