Solaris 2.4 (with patch 102209-01) allows cachfs mounting of
/ and /usr.  Solaris 2.3 doesn't allow either.

Solaris 2.4 it doesn't support cachefs mounting of /usr and /usr/kvm alone,
unless the cache exists in /.

The cachefs code in autoinstall is in prepearation of the possibility
to cachefs mount /usr when the cache lives on a seperate filesystem
but is configured for a cache in the root filesystem.

Mounting / as a cachefs filesystems makes a lot of sense:
most of / are files only used at boot time (/kernel, /sbin).

Casper
