xref: /openbmc/linux/fs/cramfs/Kconfig (revision 9726bfcd)
1 # SPDX-License-Identifier: GPL-2.0-only
2 config 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.txt> 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 
27 config 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 
35 config 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