OK, so some people like to put wildcard probes in their kernel configs:

    sd* at scsibus ? target ? lun ?

and other people would prefer to wire down everything:

    sd0 at scsibus 0 target 0 lun 0
    sd1 at scsibus 0 target 0 lun 1
    ...
    sd128 at scsibus 1 target 0 lun 0
    sd129 at scsibus 1 target 0 lun 1
    ...
    sd511 at scsibus 3 target 15 lun 7

but they don't want to explicitly write so many lines in their kernel
config files for devices that they might never have.

What if we could summarise the huge list above in one line:

    sd[128*a+8*b+c] at scsibus [a] target [b] lun [c]

This could be done by having config(8) expand the arithmetic into a huge
table in the kernel, or by doing the arithmetic at probe time in the
kernel.

--apb (Alan Barrett)