1config SQUASHFS
2	tristate "SquashFS 4.0 - Squashed file system support"
3	depends on BLOCK
4	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
7	  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
13	  timestamps.
14
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),
22	  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.
25
26	  If unsure, say N.
27
28config SQUASHFS_XATTR
29	bool "Squashfs XATTR support"
30	depends on SQUASHFS
31	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
38config 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
51config SQUASHFS_LZO
52	bool "Include support for LZO compressed file systems"
53	depends on SQUASHFS
54	select LZO_DECOMPRESS
55	help
56	  Saying Y here includes support for reading Squashfs file systems
57	  compressed with LZO compression.  LZO compression is mainly
58	  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.
65
66config 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
72	  compressed with XZ compression.  XZ gives better compression than
73	  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
81config 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
103config SQUASHFS_EMBEDDED
104	bool "Additional option for memory-constrained systems"
105	depends on SQUASHFS
106	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.
124