Purpose of CD9660_ROOT

[Peter Jeremy]

RELENG_4 documents a config option:
options         CD9660_ROOT             #ISO 9660 Filesystem usable as root
but I am unable to find any other reference to this option.  I can confirm
that CD9660_ROOT is _not_ necessary for 4.10 (at least) boot off a CD-ROM
and use it as root.

The last reference I can find is in ARCH/ARCH/autoconf.c from whence
it was deleted well before RELENG_4_BP.  Have I missed something or
is this option a total no-op?

-- 
Peter Jeremy