# SPDX-License-Identifier: GPL-2.0-only
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config CRAMFS
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tristate "Compressed ROM file system support (cramfs)"
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select ZLIB_INFLATE
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help
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Saying Y here includes support for CramFs (Compressed ROM File
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System). CramFs is designed to be a simple, small, and compressed
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file system for ROM based embedded systems. CramFs is read-only,
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limited to 256MB file systems (with 16MB files), and doesn't support
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16/32 bits uid/gid, hard links and timestamps.
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See <file:Documentation/filesystems/cramfs.rst> and
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<file:fs/cramfs/README> for further information.
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To compile this as a module, choose M here: the module will be called
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cramfs. Note that the root file system (the one containing the
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directory /) cannot be compiled as a module.
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This filesystem is limited in capabilities and performance on
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purpose to remain small and low on RAM usage. It is most suitable
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for small embedded systems. If you have ample RAM to spare, you may
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consider a more capable compressed filesystem such as SquashFS
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which is much better in terms of performance and features.
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If unsure, say N.
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config CRAMFS_BLOCKDEV
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bool "Support CramFs image over a regular block device" if EXPERT
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depends on CRAMFS && BLOCK
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default y
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help
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This option allows the CramFs driver to load data from a regular
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block device such a disk partition or a ramdisk.
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config CRAMFS_MTD
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bool "Support CramFs image directly mapped in physical memory"
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depends on CRAMFS && CRAMFS <= MTD
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default y if !CRAMFS_BLOCKDEV
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help
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This option allows the CramFs driver to load data directly from
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a linear adressed memory range (usually non volatile memory
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like flash) instead of going through the block device layer.
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This saves some memory since no intermediate buffering is
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necessary.
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The location of the CramFs image is determined by a
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MTD device capable of direct memory mapping e.g. from
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the 'physmap' map driver or a resulting MTD partition.
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For example, this would mount the cramfs image stored in
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the MTD partition named "xip_fs" on the /mnt mountpoint:
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mount -t cramfs mtd:xip_fs /mnt
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If unsure, say N.
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