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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