124 lines
4.4 KiB
Plaintext
124 lines
4.4 KiB
Plaintext
|
config SQUASHFS
|
||
|
|
tristate "SquashFS 4.0 - Squashed file system support"
|
||
|
|
depends on BLOCK
|
||
|
|
help
|
||
|
|
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. 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.
|
||
|
|
|
||
|
|
config SQUASHFS_XATTR
|
||
|
|
bool "Squashfs XATTR support"
|
||
|
|
depends on SQUASHFS
|
||
|
|
help
|
||
|
|
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.
|
||
|
|
|
||
|
|
config SQUASHFS_ZLIB
|
||
|
|
bool "Include support for ZLIB compressed file systems"
|
||
|
|
depends on SQUASHFS
|
||
|
|
select ZLIB_INFLATE
|
||
|
|
default y
|
||
|
|
help
|
||
|
|
ZLIB compression is the standard compression used by Squashfs
|
||
|
|
file systems. It offers a good trade-off between compression
|
||
|
|
achieved and the amount of CPU time and memory necessary to
|
||
|
|
compress and decompress.
|
||
|
|
|
||
|
|
If unsure, say Y.
|
||
|
|
|
||
|
|
config SQUASHFS_LZO
|
||
|
|
bool "Include support for LZO compressed file systems"
|
||
|
|
depends on SQUASHFS
|
||
|
|
select LZO_DECOMPRESS
|
||
|
|
help
|
||
|
|
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.
|
||
|
|
|
||
|
|
config SQUASHFS_XZ
|
||
|
|
bool "Include support for XZ compressed file systems"
|
||
|
|
depends on SQUASHFS
|
||
|
|
select XZ_DEC
|
||
|
|
help
|
||
|
|
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.
|
||
|
|
|
||
|
|
config SQUASHFS_4K_DEVBLK_SIZE
|
||
|
|
bool "Use 4K device block size?"
|
||
|
|
depends on SQUASHFS
|
||
|
|
help
|
||
|
|
By default Squashfs sets the dev block size (sb_min_blocksize)
|
||
|
|
to 1K or the smallest block size supported by the block device
|
||
|
|
(if larger). This, because blocks are packed together and
|
||
|
|
unaligned in Squashfs, should reduce latency.
|
||
|
|
|
||
|
|
This, however, gives poor performance on MTD NAND devices where
|
||
|
|
the optimal I/O size is 4K (even though the devices can support
|
||
|
|
smaller block sizes).
|
||
|
|
|
||
|
|
Using a 4K device block size may also improve overall I/O
|
||
|
|
performance for some file access patterns (e.g. sequential
|
||
|
|
accesses of files in filesystem order) on all media.
|
||
|
|
|
||
|
|
Setting this option will force Squashfs to use a 4K device block
|
||
|
|
size by default.
|
||
|
|
|
||
|
|
If unsure, say N.
|
||
|
|
|
||
|
|
config SQUASHFS_EMBEDDED
|
||
|
|
bool "Additional option for memory-constrained systems"
|
||
|
|
depends on SQUASHFS
|
||
|
|
help
|
||
|
|
Saying Y here allows you to specify cache size.
|
||
|
|
|
||
|
|
If unsure, say N.
|
||
|
|
|
||
|
|
config SQUASHFS_FRAGMENT_CACHE_SIZE
|
||
|
|
int "Number of fragments cached" if SQUASHFS_EMBEDDED
|
||
|
|
depends on SQUASHFS
|
||
|
|
default "3"
|
||
|
|
help
|
||
|
|
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.
|