fs/squashfs/Kconfig v3.0-rc7

SQUASHFS

SquashFS 4.0 - Squashed file system support

Saying Y here includes support for SquashFS 4.0 (a Compressed
Read-Only File System).  Squashfs is a highly compressed read-only
filesystem for Linux.  It uses zlib, lzo or xz 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 1 Mbytes
(default block size 128K).  SquashFS 4.0 supports 64 bit filesystems
and files (larger than 4GB), full uid/gid information, hard links and
timestamps.

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
embedded systems where low overhead is needed.  Further information
and tools are available from http://squashfs.sourceforge.net.

If you want to compile this as a module ( = code which can be
inserted in and removed from the running kernel whenever you want),
say M here and read <file:Documentation/modules.txt>.  The module
will be called squashfs.  Note that the root file system (the one
containing the directory /) cannot be compiled as a module.

If unsure, say N.

SQUASHFS_XATTR

Squashfs XATTR support

Saying Y here includes support for extended attributes (xattrs).
Xattrs are name:value pairs associated with inodes by
the kernel or by users (see the attr(5) manual page).

If unsure, say N.

SQUASHFS_LZO

Include support for LZO compressed file systems

Saying Y here includes support for reading Squashfs file systems
compressed with LZO compression.  LZO compression is mainly
aimed at embedded systems with slower CPUs where the overheads
of zlib are too high.

LZO is not the standard compression used in Squashfs and so most
file systems will be readable without selecting this option.

If unsure, say N.

SQUASHFS_XZ

Include support for XZ compressed file systems

Saying Y here includes support for reading Squashfs file systems
compressed with XZ compression.  XZ gives better compression than
the default zlib compression, at the expense of greater CPU and
memory overhead.

XZ is not the standard compression used in Squashfs and so most
file systems will be readable without selecting this option.

If unsure, say N.

SQUASHFS_EMBEDDED

Additional option for memory-constrained systems

Saying Y here allows you to specify cache size.

If unsure, say N.

SQUASHFS_FRAGMENT_CACHE_SIZE

Number of fragments cached

By default SquashFS caches the last 3 fragments read from
the filesystem.  Increasing this amount may mean SquashFS
has to re-read fragments less often from disk, at the expense
of extra system memory.  Decreasing this amount will mean
SquashFS uses less memory at the expense of extra reads from disk.

Note there must be at least one cached fragment.  Anything
much more than three will probably not make much difference.