buildroot/fs/erofs/Config.in

config BR2_TARGET_ROOTFS_EROFS
	bool "erofs root filesystem"
	select BR2_PACKAGE_HOST_EROFS_UTILS
	help
	  Build a EROFS root filesystem.

if BR2_TARGET_ROOTFS_EROFS

choice
	prompt "Compression algorithm"
	default BR2_TARGET_ROOTFS_EROFS_LZ4HC
	help
	  Select the EROFS compression algorithm to use.

	  LZ4HC (LZ4 High Compression) is the default algorithm and
	  provides a good balance between compression ratio and speed,
	  with increasing levels the compression ratio increases at the
	  penalty of higher compression times, without significant
	  decompression penalty.

	  LZMA provides the best compression ratio but is significantly
	  slower both in compression and decompression, and higher
	  compression levels can have noticeable memory requirements.

	  Custom compression allows for advanced configuration of the
	  compression algorithms, and adds the possibility of
	  finegrained per-file compression using compression hints.

config BR2_TARGET_ROOTFS_EROFS_NONE
	bool "no compression"

config BR2_TARGET_ROOTFS_EROFS_LZ4HC
	bool "lz4hc"

config BR2_TARGET_ROOTFS_EROFS_LZMA
	bool "lzma"

config BR2_TARGET_ROOTFS_EROFS_CUSTOM_COMPRESSION
	bool "custom"

endchoice

if BR2_TARGET_ROOTFS_EROFS_LZ4HC

config BR2_TARGET_ROOTFS_EROFS_LZ4HC_LEVEL
	int "lz4hc compression level"
	default 9
	range 1 12
	help
	  Specify the compression level for LZ4HC compression.

endif # BR2_TARGET_ROOTFS_EROFS_LZ4HC

if BR2_TARGET_ROOTFS_EROFS_LZMA

config BR2_TARGET_ROOTFS_EROFS_LZMA_LEVEL
	int "lzma compression level"
	default 6
	range 0 109
	help
	  Specify the compression level for LZMA compression.

	  Values from 0 to 9 are used for the standard compression,
	  values from 100 to 109 are used for the extreme compression.

endif # BR2_TARGET_ROOTFS_EROFS_LZMA

if BR2_TARGET_ROOTFS_EROFS_CUSTOM_COMPRESSION

config BR2_TARGET_ROOTFS_EROFS_COMPRESSION_ALGORITHMS
	string "compression algorithms"
	default "lz4hc,12"
	help
	  Specify arbitrary compression option, useful in combination
	  with compression hints. Individual algorithms are separated
	  by colon with optional level, e.g. "lz4hc,12:lzma".
	  See erofs-utils documentaion for detailed information.

config BR2_TARGET_ROOTFS_EROFS_COMPRESSION_HINTS
	string "path to compression hints file"
	default ""
	help
	  Path to file containing compression hints. Each line in the
	  file is defined by tokens separated by spaces in the
	  following form. Optionally, instead of the given primary
	  algorithm, algorithms can be specified with zero-based
	  algorithm-index explicitly:

	  <pcluster-size-in-bytes> [algorithm-index] <match-pattern>

	  match-patterns are extended regular expressions, matched
	  against absolute paths within the output filesystem, with no
	  leading /.

endif # BR2_TARGET_ROOTFS_EROFS_LZMA

config BR2_TARGET_ROOTFS_EROFS_DEDUPE
	bool "enable data deduplication"
	depends on !BR2_TARGET_ROOTFS_EROFS_NONE
	help
	  Enable global compressed data deduplication to reduce FS image
	  size. Introduced in Linux 6.1.

config BR2_TARGET_ROOTFS_EROFS_FRAGMENTS
	bool "enable fragments packing"
	help
	  Pack the tail part (pcluster) of compressed files, or entire
	  files, into a special inode for smaller image size.
	  Introduced in Linux 6.1.

config BR2_TARGET_ROOTFS_EROFS_ALL_FRAGMENTS
	bool "enable all-fragments packing"
	help
	  Forcely record the whole files into a special inode for better
	  compression. Introduced in Linux 6.1.

config BR2_TARGET_ROOTFS_EROFS_ZTAILPACKING
	bool "enable ztailpacking"
	help
	  Pack the tail part (pcluster) of compressed files into its
	  metadata to save more space and the tail part I/O. Introduced
	  in Linux 5.17.

config BR2_TARGET_ROOTFS_EROFS_PCLUSTERSIZE
	int "pcluster size"
	default 0
	help
	  Specify the maximum size of physical cluster in bytes, as a
	  multiple of 4KiB, for the big pcluster feature in order to
	  get much better compression ratios (thus better sequential
	  read performance for common storage devices), which has been
	  introduced since Linux 5.13.

endif # BR2_TARGET_ROOTFS_EROFS