1 # SPDX-License-Identifier: GPL-2.0-only <<
2 config CRAMFS 1 config CRAMFS
3 tristate "Compressed ROM file system s 2 tristate "Compressed ROM file system support (cramfs)"
4 select ZLIB_INFLATE 3 select ZLIB_INFLATE
5 help 4 help
6 Saying Y here includes support for C 5 Saying Y here includes support for CramFs (Compressed ROM File
7 System). CramFs is designed to be a 6 System). CramFs is designed to be a simple, small, and compressed
8 file system for ROM based embedded s 7 file system for ROM based embedded systems. CramFs is read-only,
9 limited to 256MB file systems (with 8 limited to 256MB file systems (with 16MB files), and doesn't support
10 16/32 bits uid/gid, hard links and t 9 16/32 bits uid/gid, hard links and timestamps.
11 10
12 See <file:Documentation/filesystems/ !! 11 See <file:Documentation/filesystems/cramfs.txt> and
13 <file:fs/cramfs/README> for further 12 <file:fs/cramfs/README> for further information.
14 13
15 To compile this as a module, choose 14 To compile this as a module, choose M here: the module will be called
16 cramfs. Note that the root file sys 15 cramfs. Note that the root file system (the one containing the
17 directory /) cannot be compiled as a 16 directory /) cannot be compiled as a module.
18 17
19 This filesystem is limited in capabi 18 This filesystem is limited in capabilities and performance on
20 purpose to remain small and low on R 19 purpose to remain small and low on RAM usage. It is most suitable
21 for small embedded systems. If you h 20 for small embedded systems. If you have ample RAM to spare, you may
22 consider a more capable compressed f 21 consider a more capable compressed filesystem such as SquashFS
23 which is much better in terms of per 22 which is much better in terms of performance and features.
24 23
25 If unsure, say N. 24 If unsure, say N.
26 25
27 config CRAMFS_BLOCKDEV 26 config CRAMFS_BLOCKDEV
28 bool "Support CramFs image over a regu 27 bool "Support CramFs image over a regular block device" if EXPERT
29 depends on CRAMFS && BLOCK 28 depends on CRAMFS && BLOCK
30 default y 29 default y
31 help 30 help
32 This option allows the CramFs driver 31 This option allows the CramFs driver to load data from a regular
33 block device such a disk partition o 32 block device such a disk partition or a ramdisk.
34 33
35 config CRAMFS_MTD 34 config CRAMFS_MTD
36 bool "Support CramFs image directly ma 35 bool "Support CramFs image directly mapped in physical memory"
37 depends on CRAMFS && CRAMFS <= MTD 36 depends on CRAMFS && CRAMFS <= MTD
38 default y if !CRAMFS_BLOCKDEV 37 default y if !CRAMFS_BLOCKDEV
39 help 38 help
40 This option allows the CramFs driver 39 This option allows the CramFs driver to load data directly from
41 a linear addressed memory range (usu !! 40 a linear adressed memory range (usually non volatile memory
42 like flash) instead of going through 41 like flash) instead of going through the block device layer.
43 This saves some memory since no inte 42 This saves some memory since no intermediate buffering is
44 necessary. 43 necessary.
45 44
46 The location of the CramFs image is 45 The location of the CramFs image is determined by a
47 MTD device capable of direct memory 46 MTD device capable of direct memory mapping e.g. from
48 the 'physmap' map driver or a result 47 the 'physmap' map driver or a resulting MTD partition.
49 For example, this would mount the cr 48 For example, this would mount the cramfs image stored in
50 the MTD partition named "xip_fs" on 49 the MTD partition named "xip_fs" on the /mnt mountpoint:
51 50
52 mount -t cramfs mtd:xip_fs /mnt 51 mount -t cramfs mtd:xip_fs /mnt
53 52
54 If unsure, say N. 53 If unsure, say N.
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