	SQUASHFS 4.1 - A squashed read-only filesystem for Linux

	Copyright 2002-2010 Phillip Lougher <phillip@lougher.demon.co.uk>

	Released under the GPL licence (version 2 or later).

Welcome to Squashfs version 4.1.  Please read the README-4.1 and CHANGES files
for details of changes.

Squashfs is a highly compressed read-only filesystem for Linux.
It uses zlib compression to compress both files, inodes and directories.
Inodes in the system are very small and all blocks are packed to minimise
data overhead. Block sizes greater than 4K are supported up to a maximum
of 1Mbytes (default block size 128K).

Squashfs is intended for general read-only filesystem use, for archival
use (i.e. in cases where a .tar.gz file may be used), and in constrained
block device/memory systems (e.g. embedded systems) where low overhead is
needed.

1. SQUASHFS OVERVIEW
--------------------

1. Data, inodes and directories are compressed.

2. Squashfs stores full uid/gids (32 bits), and file creation time.

3. In theory files up to 2^64 bytes are supported.  In theory filesystems can
   be up to 2^64 bytes.

4. Inode and directory data are highly compacted, and packed on byte
   boundaries.  Each compressed inode is on average 8 bytes in length
   (the exact length varies on file type, i.e. regular file, directory,
   symbolic link, and block/char device inodes have different sizes).

5. Squashfs can use block sizes up to 1Mbyte (the default size is 128K).
   Using 128K blocks achieves greater compression ratios than the normal
   4K block size.

6. File duplicates are detected and removed.

7. Both big and little endian architectures are supported.  Squashfs can
   mount filesystems created on different byte order machines.


2. USING SQUASHFS
-----------------

Squashfs filesystems should be mounted with 'mount' with the filesystem type
'squashfs'.  If the filesystem is on a block device, the filesystem can be
mounted directly, e.g.

%mount -t squashfs /dev/sda1 /mnt

Will mount the squashfs filesystem on "/dev/sda1" under the directory "/mnt".

If the squashfs filesystem has been written to a file, the loopback device
can be used to mount it (loopback support must be in the kernel), e.g.

%mount -t squashfs image /mnt -o loop

Will mount the squashfs filesystem in the file "image" under
the directory "/mnt".


3. MKSQUASHFS
-------------

3.1 Mksquashfs options and overview.
------------------------------------

As squashfs is a read-only filesystem, the mksquashfs program must be used to
create populated squashfs filesystems.

SYNTAX:mksquashfs source1 source2 ...  dest [options] [-e list of exclude
dirs/files]

Filesystem build options:
-comp <comp>		select <comp> compression
			Compressors available:
				gzip (default)
				lzma
				lzo
-b <block_size>		set data block to <block_size>.  Default 131072 bytes
-no-exports		don't make the filesystem exportable via NFS
-no-sparse		don't detect sparse files
-no-xattrs		don't store extended attributes
-xattrs			store extended attributes (default)
-noI			do not compress inode table
-noD			do not compress data blocks
-noF			do not compress fragment blocks
-noX			do not compress extended attributes
-no-fragments		do not use fragments
-always-use-fragments	use fragment blocks for files larger than block size
-no-duplicates		do not perform duplicate checking
-all-root		make all files owned by root
-force-uid uid		set all file uids to uid
-force-gid gid		set all file gids to gid
-nopad			do not pad filesystem to a multiple of 4K
-keep-as-directory	if one source directory is specified, create a root
			directory containing that directory, rather than the
			contents of the directory

Filesystem filter options:
-p <pseudo-definition>	Add pseudo file definition
-pf <pseudo-file>	Add list of pseudo file definitions
-sort <sort_file>	sort files according to priorities in <sort_file>.  One
			file or dir with priority per line.  Priority -32768 to
			32767, default priority 0
-ef <exclude_file>	list of exclude dirs/files.  One per line
-wildcards		Allow extended shell wildcards (globbing) to be used in
			exclude dirs/files
-regex			Allow POSIX regular expressions to be used in exclude
			dirs/files

Filesystem append options:
-noappend		do not append to existing filesystem
-root-becomes <name>	when appending source files/directories, make the
			original root become a subdirectory in the new root
			called <name>, rather than adding the new source items
			to the original root

Mksquashfs runtime options:
-version		print version, licence and copyright message
-recover <name>		recover filesystem data using recovery file <name>
-no-recovery		don't generate a recovery file
-info			print files written to filesystem
-no-progress		don't display the progress bar
-processors <number>	Use <number> processors.  By default will use number of
			processors available
-read-queue <size>	Set input queue to <size> Mbytes.  Default 64 Mbytes
-write-queue <size>	Set output queue to <size> Mbytes.  Default 512 Mbytes
-fragment-queue <size>	Set fagment queue to <size> Mbytes.  Default 64 Mbytes

Miscellaneous options                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 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