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Alexey Dobriyan22635ec2009-01-22 10:57:46 +03001config SQUASHFS
2 tristate "SquashFS 4.0 - Squashed file system support"
3 depends on BLOCK
Alexey Dobriyan22635ec2009-01-22 10:57:46 +03004 help
5 Saying Y here includes support for SquashFS 4.0 (a Compressed
6 Read-Only File System). Squashfs is a highly compressed read-only
Phillip Lougher681ffe22011-02-28 16:21:34 +00007 filesystem for Linux. It uses zlib, lzo or xz compression to
8 compress both files, inodes and directories. Inodes in the system
9 are very small and all blocks are packed to minimise data overhead.
10 Block sizes greater than 4K are supported up to a maximum of 1 Mbytes
11 (default block size 128K). SquashFS 4.0 supports 64 bit filesystems
12 and files (larger than 4GB), full uid/gid information, hard links and
Phillip Lougher4b676d22010-08-05 23:42:54 +010013 timestamps.
Alexey Dobriyan22635ec2009-01-22 10:57:46 +030014
15 Squashfs is intended for general read-only filesystem use, for
16 archival use (i.e. in cases where a .tar.gz file may be used), and in
17 embedded systems where low overhead is needed. Further information
18 and tools are available from http://squashfs.sourceforge.net.
19
20 If you want to compile this as a module ( = code which can be
21 inserted in and removed from the running kernel whenever you want),
Paul Bolle395cf962011-08-15 02:02:26 +020022 say M here. The module will be called squashfs. Note that the root
23 file system (the one containing the directory /) cannot be compiled
24 as a module.
Alexey Dobriyan22635ec2009-01-22 10:57:46 +030025
26 If unsure, say N.
27
Phillip Lougher637d5c92010-05-31 18:46:29 +010028config SQUASHFS_XATTR
Phillip Lougher01e5b4e2010-05-17 19:39:02 +010029 bool "Squashfs XATTR support"
30 depends on SQUASHFS
Phillip Lougher01e5b4e2010-05-17 19:39:02 +010031 help
32 Saying Y here includes support for extended attributes (xattrs).
33 Xattrs are name:value pairs associated with inodes by
34 the kernel or by users (see the attr(5) manual page).
35
36 If unsure, say N.
37
Phillip Loughercc6d3492011-07-22 03:01:28 +010038config SQUASHFS_ZLIB
39 bool "Include support for ZLIB compressed file systems"
40 depends on SQUASHFS
41 select ZLIB_INFLATE
42 default y
43 help
44 ZLIB compression is the standard compression used by Squashfs
45 file systems. It offers a good trade-off between compression
46 achieved and the amount of CPU time and memory necessary to
47 compress and decompress.
48
49 If unsure, say Y.
50
Chan Jeong79cb8ce2010-08-05 02:29:59 +010051config SQUASHFS_LZO
52 bool "Include support for LZO compressed file systems"
53 depends on SQUASHFS
54 select LZO_DECOMPRESS
Phillip Lougher4b676d22010-08-05 23:42:54 +010055 help
56 Saying Y here includes support for reading Squashfs file systems
Justin P. Mattock70f23fd2011-05-10 10:16:21 +020057 compressed with LZO compression. LZO compression is mainly
Phillip Lougher4b676d22010-08-05 23:42:54 +010058 aimed at embedded systems with slower CPUs where the overheads
59 of zlib are too high.
60
61 LZO is not the standard compression used in Squashfs and so most
62 file systems will be readable without selecting this option.
63
64 If unsure, say N.
Chan Jeong79cb8ce2010-08-05 02:29:59 +010065
Phillip Lougher7a43ae52010-12-09 02:08:31 +000066config SQUASHFS_XZ
67 bool "Include support for XZ compressed file systems"
68 depends on SQUASHFS
69 select XZ_DEC
70 help
71 Saying Y here includes support for reading Squashfs file systems
Justin P. Mattock70f23fd2011-05-10 10:16:21 +020072 compressed with XZ compression. XZ gives better compression than
Phillip Lougher7a43ae52010-12-09 02:08:31 +000073 the default zlib compression, at the expense of greater CPU and
74 memory overhead.
75
76 XZ is not the standard compression used in Squashfs and so most
77 file systems will be readable without selecting this option.
78
79 If unsure, say N.
80
Phillip Lougher7657cac2011-10-22 01:34:48 +010081config SQUASHFS_4K_DEVBLK_SIZE
82 bool "Use 4K device block size?"
83 depends on SQUASHFS
84 help
85 By default Squashfs sets the dev block size (sb_min_blocksize)
86 to 1K or the smallest block size supported by the block device
87 (if larger). This, because blocks are packed together and
88 unaligned in Squashfs, should reduce latency.
89
90 This, however, gives poor performance on MTD NAND devices where
91 the optimal I/O size is 4K (even though the devices can support
92 smaller block sizes).
93
94 Using a 4K device block size may also improve overall I/O
95 performance for some file access patterns (e.g. sequential
96 accesses of files in filesystem order) on all media.
97
98 Setting this option will force Squashfs to use a 4K device block
99 size by default.
100
101 If unsure, say N.
102
Alexey Dobriyan22635ec2009-01-22 10:57:46 +0300103config SQUASHFS_EMBEDDED
Phillip Lougher4b676d22010-08-05 23:42:54 +0100104 bool "Additional option for memory-constrained systems"
Alexey Dobriyan22635ec2009-01-22 10:57:46 +0300105 depends on SQUASHFS
Alexey Dobriyan22635ec2009-01-22 10:57:46 +0300106 help
107 Saying Y here allows you to specify cache size.
108
109 If unsure, say N.
110
111config SQUASHFS_FRAGMENT_CACHE_SIZE
112 int "Number of fragments cached" if SQUASHFS_EMBEDDED
113 depends on SQUASHFS
114 default "3"
115 help
116 By default SquashFS caches the last 3 fragments read from
117 the filesystem. Increasing this amount may mean SquashFS
118 has to re-read fragments less often from disk, at the expense
119 of extra system memory. Decreasing this amount will mean
120 SquashFS uses less memory at the expense of extra reads from disk.
121
122 Note there must be at least one cached fragment. Anything
123 much more than three will probably not make much difference.