Kernel crash before dumpon

[Wojciech Puchar]

>
> The page includes the following suggestion on how I might be able to
> proceed:
>        Alternatively, the dump device can be hard-coded via the
>        dump clause in the config(5) line of a kernel configuration
>        file. This approach is deprecated and should be used only
>        if a kernel is crashing before dumpon(8) can be executed.
>
> I tried adding
>        config dump "/dev/ad4s3b"
> to the configuration file but that option appears to be no longer
> supported: the config command gives an error message of:
>        root/dump/swap specification obsolete
>
> Is the paragraph above obsolete?  If so, what's the preferred way to
> collect the dump?
>
> Thanks
>
>
in rc.conf

dumpdev="/dev/dumpdevice"