$FreeBSD: release/9.2.0/sys/cddl/boot/zfs/README 247309 2013-02-26 05:58:05Z delphij $

This directory contains various files derived from CDDL sources that
are used by the ZFS bootstrap:

    fletcher.c			checksum support
    sha256.c			checksum support
    lz4.c			compression support
    lzjb.c			compression support
    zfssubr.c			checksum, compression and raidz support
    zfsimpl.h			mostly describing the physical layout

The files fletcher.c, lzjb.c and sha256.c are largely identical to the
ZFS base code (with write support removed) and could be shared but
that might complicate future imports from OpenSolaris.
