# SPDX-License-Identifier: GPL-2.0

  #
  # Configuration for initramfs
  #
  
  config INITRAMFS_SOURCE
  	string "Initramfs source file(s)"
  	default ""
  	help
  	  This can be either a single cpio archive with a .cpio suffix or a
  	  space-separated list of directories and files for building the
  	  initramfs image.  A cpio archive should contain a filesystem archive
  	  to be used as an initramfs image.  Directories should contain a
  	  filesystem layout to be included in the initramfs image.  Files
  	  should contain entries according to the format described by the
  	  "usr/gen_init_cpio" program in the kernel tree.
  
  	  When multiple directories and files are specified then the
  	  initramfs image will be the aggregate of all of them.

  	  See <file:Documentation/driver-api/early-userspace/early_userspace_support.rst> for more details.

  
  	  If you are not sure, leave it blank.

  config INITRAMFS_FORCE
  	bool "Ignore the initramfs passed by the bootloader"
  	depends on CMDLINE_EXTEND || CMDLINE_FORCE
  	help
  	  This option causes the kernel to ignore the initramfs image
  	  (or initrd image) passed to it by the bootloader. This is
  	  analogous to CMDLINE_FORCE, which is found on some architectures,
  	  and is useful if you cannot or don't want to change the image
  	  your bootloader passes to the kernel.

  config INITRAMFS_ROOT_UID
  	int "User ID to map to 0 (user root)"
  	depends on INITRAMFS_SOURCE!=""
  	default "0"
  	help

  	  If INITRAMFS_SOURCE points to a directory, files owned by this UID
  	  (-1 = current user) will be owned by root in the resulting image.

  
  	  If you are not sure, leave it set to "0".
  
  config INITRAMFS_ROOT_GID
  	int "Group ID to map to 0 (group root)"
  	depends on INITRAMFS_SOURCE!=""
  	default "0"
  	help

  	  If INITRAMFS_SOURCE points to a directory, files owned by this GID
  	  (-1 = current group) will be owned by root in the resulting image.

  
  	  If you are not sure, leave it set to "0".

  
  config RD_GZIP

  	bool "Support initial ramdisk/ramfs compressed using gzip"

  	default y

  	select DECOMPRESS_GZIP
  	help
  	  Support loading of a gzip encoded initial ramdisk or cpio buffer.
  	  If unsure, say Y.
  
  config RD_BZIP2

  	bool "Support initial ramdisk/ramfs compressed using bzip2"

  	default y

  	select DECOMPRESS_BZIP2
  	help
  	  Support loading of a bzip2 encoded initial ramdisk or cpio buffer
  	  If unsure, say N.
  
  config RD_LZMA

  	bool "Support initial ramdisk/ramfs compressed using LZMA"

  	default y

  	select DECOMPRESS_LZMA
  	help

  	  Support loading of a LZMA encoded initial ramdisk or cpio buffer

  	  If unsure, say N.

  config RD_XZ

  	bool "Support initial ramdisk/ramfs compressed using XZ"

  	default y

  	select DECOMPRESS_XZ
  	help
  	  Support loading of a XZ encoded initial ramdisk or cpio buffer.
  	  If unsure, say N.

  config RD_LZO

  	bool "Support initial ramdisk/ramfs compressed using LZO"

  	default y

  	select DECOMPRESS_LZO
  	help
  	  Support loading of a LZO encoded initial ramdisk or cpio buffer
  	  If unsure, say N.

  config RD_LZ4

  	bool "Support initial ramdisk/ramfs compressed using LZ4"

  	default y

  	select DECOMPRESS_LZ4
  	help
  	  Support loading of a LZ4 encoded initial ramdisk or cpio buffer
  	  If unsure, say N.

  config RD_ZSTD
  	bool "Support initial ramdisk/ramfs compressed using ZSTD"
  	default y
  	depends on BLK_DEV_INITRD
  	select DECOMPRESS_ZSTD
  	help
  	  Support loading of a ZSTD encoded initial ramdisk or cpio buffer.
  	  If unsure, say N.

  choice
  	prompt "Built-in initramfs compression mode"

  	depends on INITRAMFS_SOURCE != ""

  	help
  	  This option allows you to decide by which algorithm the builtin
  	  initramfs will be compressed.  Several compression algorithms are
  	  available, which differ in efficiency, compression and
  	  decompression speed.  Compression speed is only relevant
  	  when building a kernel.  Decompression speed is relevant at
  	  each boot. Also the memory usage during decompression may become
  	  relevant on memory constrained systems. This is usually based on the
  	  dictionary size of the algorithm with algorithms like XZ and LZMA
  	  featuring large dictionary sizes.
  
  	  High compression options are mostly useful for users who are
  	  low on RAM, since it reduces the memory consumption during
  	  boot.
  
  	  Keep in mind that your build system needs to provide the appropriate
  	  compression tool to compress the generated initram cpio file for
  	  embedding.
  
  	  If in doubt, select 'None'

  config INITRAMFS_COMPRESSION_GZIP
  	bool "Gzip"
  	depends on RD_GZIP
  	help
  	  Use the old and well tested gzip compression algorithm. Gzip provides
  	  a good balance between compression ratio and decompression speed and
  	  has a reasonable compression speed. It is also more likely to be
  	  supported by your build system as the gzip tool is present by default
  	  on most distros.
  
  config INITRAMFS_COMPRESSION_BZIP2
  	bool "Bzip2"
  	depends on RD_BZIP2
  	help
  	  It's compression ratio and speed is intermediate. Decompression speed
  	  is slowest among the choices. The initramfs size is about 10% smaller
  	  with bzip2, in comparison to gzip. Bzip2 uses a large amount of
  	  memory. For modern kernels you will need at least 8MB RAM or more for
  	  booting.
  
  	  If you choose this, keep in mind that you need to have the bzip2 tool
  	  available to be able to compress the initram.
  
  config INITRAMFS_COMPRESSION_LZMA
  	bool "LZMA"
  	depends on RD_LZMA
  	help
  	  This algorithm's compression ratio is best but has a large dictionary
  	  size which might cause issues in memory constrained systems.
  	  Decompression speed is between the other choices. Compression is
  	  slowest. The initramfs size is about 33% smaller with LZMA in
  	  comparison to gzip.
  
  	  If you choose this, keep in mind that you may need to install the xz
  	  or lzma tools to be able to compress the initram.
  
  config INITRAMFS_COMPRESSION_XZ
  	bool "XZ"
  	depends on RD_XZ
  	help
  	  XZ uses the LZMA2 algorithm and has a large dictionary which may cause
  	  problems on memory constrained systems. The initramfs size is about
  	  30% smaller with XZ in comparison to gzip. Decompression speed is
  	  better than that of bzip2 but worse than gzip and LZO. Compression is
  	  slow.
  
  	  If you choose this, keep in mind that you may need to install the xz
  	  tool to be able to compress the initram.
  
  config INITRAMFS_COMPRESSION_LZO
  	bool "LZO"
  	depends on RD_LZO
  	help
  	  It's compression ratio is the second poorest amongst the choices. The
  	  kernel size is about 10% bigger than gzip. Despite that, it's
  	  decompression speed is the second fastest and it's compression speed
  	  is quite fast too.
  
  	  If you choose this, keep in mind that you may need to install the lzop
  	  tool to be able to compress the initram.
  
  config INITRAMFS_COMPRESSION_LZ4
  	bool "LZ4"
  	depends on RD_LZ4
  	help
  	  It's compression ratio is the poorest amongst the choices. The kernel
  	  size is about 15% bigger than gzip; however its decompression speed
  	  is the fastest.
  
  	  If you choose this, keep in mind that most distros don't provide lz4
  	  by default which could cause a build failure.

  config INITRAMFS_COMPRESSION_ZSTD
  	bool "ZSTD"
  	depends on RD_ZSTD
  	help
  	  ZSTD is a compression algorithm targeting intermediate compression
  	  with fast decompression speed. It will compress better than GZIP and
  	  decompress around the same speed as LZO, but slower than LZ4.
  
  	  If you choose this, keep in mind that you may need to install the zstd
  	  tool to be able to compress the initram.

  config INITRAMFS_COMPRESSION_NONE
  	bool "None"
  	help
  	  Do not compress the built-in initramfs at all. This may sound wasteful
  	  in space, but, you should be aware that the built-in initramfs will be
  	  compressed at a later stage anyways along with the rest of the kernel,
  	  on those architectures that support this. However, not compressing the
  	  initramfs may lead to slightly higher memory consumption during a
  	  short time at boot, while both the cpio image and the unpacked
  	  filesystem image will be present in memory simultaneously

  endchoice