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1# SPDX-License-Identifier: GPL-2.0-only2config CRAMFS3 tristate "Compressed ROM file system support (cramfs)"4 select ZLIB_INFLATE5 help6 Saying Y here includes support for CramFs (Compressed ROM File7 System). CramFs is designed to be a simple, small, and compressed8 file system for ROM based embedded systems. CramFs is read-only,9 limited to 256MB file systems (with 16MB files), and doesn't support10 16/32 bits uid/gid, hard links and timestamps.11 12 See <file:Documentation/filesystems/cramfs.rst> and13 <file:fs/cramfs/README> for further information.14 15 To compile this as a module, choose M here: the module will be called16 cramfs. Note that the root file system (the one containing the17 directory /) cannot be compiled as a module.18 19 This filesystem is limited in capabilities and performance on20 purpose to remain small and low on RAM usage. It is most suitable21 for small embedded systems. If you have ample RAM to spare, you may22 consider a more capable compressed filesystem such as SquashFS23 which is much better in terms of performance and features.24 25 If unsure, say N.26 27config CRAMFS_BLOCKDEV28 bool "Support CramFs image over a regular block device" if EXPERT29 depends on CRAMFS && BLOCK30 default y31 help32 This option allows the CramFs driver to load data from a regular33 block device such a disk partition or a ramdisk.34 35config CRAMFS_MTD36 bool "Support CramFs image directly mapped in physical memory"37 depends on CRAMFS && CRAMFS <= MTD38 default y if !CRAMFS_BLOCKDEV39 help40 This option allows the CramFs driver to load data directly from41 a linear addressed memory range (usually non-volatile memory42 like flash) instead of going through the block device layer.43 This saves some memory since no intermediate buffering is44 necessary.45 46 The location of the CramFs image is determined by a47 MTD device capable of direct memory mapping e.g. from48 the 'physmap' map driver or a resulting MTD partition.49 For example, this would mount the cramfs image stored in50 the MTD partition named "xip_fs" on the /mnt mountpoint:51 52 mount -t cramfs mtd:xip_fs /mnt53 54 If unsure, say N.55