length separately.
Use this for foreign-endianess labels in wedge autodiscovery, and
calculate the checksum of those before we swap various fields in the
label.
disklabels nested inside an MBR "NetBSD" or "386BSD" partition (first
one found is considered authoritative for the disk), or in one of several
known locations for various NetBSD platforms. It can read native or other-
endian disklabels (code is there, but not tested).
If you want to play with this, exercise caution; you can't currently
mountroot on a wedge (setroot() needs some work). Enabled by the
DKWEDGE_METHOD_BSDLABEL kernel option.