1 SQUASHFS 4.2 - A squashed read-only filesystem for Linux 2 3 Copyright 2002-2011 Phillip Lougher <phillip (a] lougher.demon.co.uk> 4 5 Released under the GPL licence (version 2 or later). 6 7 Welcome to Squashfs 4.2. This is a tools only release, support for Squashfs 8 filesystems is in mainline (2.6.29 and later). 9 10 New features in Squashfs-tools 4.2 11 ---------------------------------- 12 13 1. Support for XZ compression 14 2. Support for compressor specific options 15 16 Compatiblity 17 ------------ 18 19 Mksquashfs 4.2 generates 4.0 filesystems. These filesystems are fully 20 compatible/interchangable with filesystems generated by Mksquashfs 4.0 and are 21 mountable on 2.6.29 and later kernels. 22 23 XZ compression 24 -------------- 25 26 Squashfs now supports XZ compression. 27 28 XZ support is in 2.6.38 and newer kernels. 29 30 New Mksquashfs options 31 ---------------------- 32 33 -X<compressor-option> 34 35 Compression algorithms can now support compression specific options. These 36 options are prefixed by -X, and are passed to the compressor for handling. 37 38 The compression specific options supported by each compressor can be 39 found by typing mksquashfs without any arguments. They are displayed at the 40 end of the help message, e.g. 41 42 Compressors available and compressor specific options: 43 gzip (no options) (default) 44 lzo (no options) 45 xz 46 -Xbcj filter1,filter2,...,filterN 47 Compress using filter1,filter2,...,filterN in turn 48 (in addition to no filter), and choose the best compression. 49 Available filters: x86, arm, armthumb, powerpc, sparc, ia64 50 -Xdict-size <dict-size> 51 Use <dict-size> as the XZ dictionary size. The dictionary size 52 can be specified as a percentage of the block size, or as an 53 absolute value. The dictionary size must be less than or equal 54 to the block size and 8192 bytes or larger. It must also be 55 storable in the xz header as either 2^n or as 2^n+2^(n+1). 56 Example dict-sizes are 75%, 50%, 37.5%, 25%, or 32K, 16K, 8K 57 etc. 58
