SQUASHFS/squashfs-tools-4.4/RELEASE-READMEs/README-4.2

   1         SQUASHFS 4.2 - A squashed read-only filesystem for Linux
   2
   3         Copyright 2002-2011 Phillip Lougher <phillip@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.