1# SPDX-License-Identifier: GPL-2.0-only 2config CRAMFS 3 tristate "Compressed ROM file system support (cramfs)" 4 select ZLIB_INFLATE 5 help 6 Saying Y here includes support for CramFs (Compressed ROM File 7 System). CramFs is designed to be a simple, small, and compressed 8 file system for ROM based embedded systems. CramFs is read-only, 9 limited to 256MB file systems (with 16MB files), and doesn't support 10 16/32 bits uid/gid, hard links and timestamps. 11 12 See <file:Documentation/filesystems/cramfs.rst> and 13 <file:fs/cramfs/README> for further information. 14 15 To compile this as a module, choose M here: the module will be called 16 cramfs. Note that the root file system (the one containing the 17 directory /) cannot be compiled as a module. 18 19 This filesystem is limited in capabilities and performance on 20 purpose to remain small and low on RAM usage. It is most suitable 21 for small embedded systems. If you have ample RAM to spare, you may 22 consider a more capable compressed filesystem such as SquashFS 23 which is much better in terms of performance and features. 24 25 If unsure, say N. 26 27config CRAMFS_BLOCKDEV 28 bool "Support CramFs image over a regular block device" if EXPERT 29 depends on CRAMFS && BLOCK 30 default y 31 help 32 This option allows the CramFs driver to load data from a regular 33 block device such a disk partition or a ramdisk. 34 35config CRAMFS_MTD 36 bool "Support CramFs image directly mapped in physical memory" 37 depends on CRAMFS && CRAMFS <= MTD 38 default y if !CRAMFS_BLOCKDEV 39 help 40 This option allows the CramFs driver to load data directly from 41 a linear adressed memory range (usually non volatile memory 42 like flash) instead of going through the block device layer. 43 This saves some memory since no intermediate buffering is 44 necessary. 45 46 The location of the CramFs image is determined by a 47 MTD device capable of direct memory mapping e.g. from 48 the 'physmap' map driver or a resulting MTD partition. 49 For example, this would mount the cramfs image stored in 50 the MTD partition named "xip_fs" on the /mnt mountpoint: 51 52 mount -t cramfs mtd:xip_fs /mnt 53 54 If unsure, say N. 55