usr/Kconfig

   1 #
   2 # Configuration for initramfs
   3 #
   4
   5 config INITRAMFS_SOURCE
   6         string "Initramfs source file(s)"
   7         default ""
   8         help
   9           This can be either a single cpio archive with a .cpio suffix or a
  10           space-separated list of directories and files for building the
  11           initramfs image.  A cpio archive should contain a filesystem archive
  12           to be used as an initramfs image.  Directories should contain a
  13           filesystem layout to be included in the initramfs image.  Files
  14           should contain entries according to the format described by the
  15           "usr/gen_init_cpio" program in the kernel tree.
  16
  17           When multiple directories and files are specified then the
  18           initramfs image will be the aggregate of all of them.
  19
  20           See <file:Documentation/early-userspace/README> for more details.
  21
  22           If you are not sure, leave it blank.
  23
  24 config INITRAMFS_FORCE
  25         bool "Ignore the initramfs passed by the bootloader"
  26         depends on CMDLINE_EXTEND || CMDLINE_FORCE
  27         help
  28           This option causes the kernel to ignore the initramfs image
  29           (or initrd image) passed to it by the bootloader. This is
  30           analogous to CMDLINE_FORCE, which is found on some architectures,
  31           and is useful if you cannot or don't want to change the image
  32           your bootloader passes to the kernel.
  33
  34 config INITRAMFS_ROOT_UID
  35         int "User ID to map to 0 (user root)"
  36         depends on INITRAMFS_SOURCE!=""
  37         default "0"
  38         help
  39           If INITRAMFS_SOURCE points to a directory, files owned by this UID
  40           (-1 = current user) will be owned by root in the resulting image.
  41
  42           If you are not sure, leave it set to "0".
  43
  44 config INITRAMFS_ROOT_GID
  45         int "Group ID to map to 0 (group root)"
  46         depends on INITRAMFS_SOURCE!=""
  47         default "0"
  48         help
  49           If INITRAMFS_SOURCE points to a directory, files owned by this GID
  50           (-1 = current group) will be owned by root in the resulting image.
  51
  52           If you are not sure, leave it set to "0".
  53
  54 config RD_GZIP
  55         bool "Support initial ramdisk/ramfs compressed using gzip"
  56         depends on BLK_DEV_INITRD
  57         default y
  58         select DECOMPRESS_GZIP
  59         help
  60           Support loading of a gzip encoded initial ramdisk or cpio buffer.
  61           If unsure, say Y.
  62
  63 config RD_BZIP2
  64         bool "Support initial ramdisk/ramfs compressed using bzip2"
  65         default y
  66         depends on BLK_DEV_INITRD
  67         select DECOMPRESS_BZIP2
  68         help
  69           Support loading of a bzip2 encoded initial ramdisk or cpio buffer
  70           If unsure, say N.
  71
  72 config RD_LZMA
  73         bool "Support initial ramdisk/ramfs compressed using LZMA"
  74         default y
  75         depends on BLK_DEV_INITRD
  76         select DECOMPRESS_LZMA
  77         help
  78           Support loading of a LZMA encoded initial ramdisk or cpio buffer
  79           If unsure, say N.
  80
  81 config RD_XZ
  82         bool "Support initial ramdisk/ramfs compressed using XZ"
  83         depends on BLK_DEV_INITRD
  84         default y
  85         select DECOMPRESS_XZ
  86         help
  87           Support loading of a XZ encoded initial ramdisk or cpio buffer.
  88           If unsure, say N.
  89
  90 config RD_LZO
  91         bool "Support initial ramdisk/ramfs compressed using LZO"
  92         default y
  93         depends on BLK_DEV_INITRD
  94         select DECOMPRESS_LZO
  95         help
  96           Support loading of a LZO encoded initial ramdisk or cpio buffer
  97           If unsure, say N.
  98
  99 config RD_LZ4
 100         bool "Support initial ramdisk/ramfs compressed using LZ4"
 101         default y
 102         depends on BLK_DEV_INITRD
 103         select DECOMPRESS_LZ4
 104         help
 105           Support loading of a LZ4 encoded initial ramdisk or cpio buffer
 106           If unsure, say N.
 107
 108 choice
 109         prompt "Built-in initramfs compression mode"
 110         depends on INITRAMFS_SOURCE!=""
 111         optional
 112         help
 113           This option allows you to decide by which algorithm the builtin
 114           initramfs will be compressed.  Several compression algorithms are
 115           available, which differ in efficiency, compression and
 116           decompression speed.  Compression speed is only relevant
 117           when building a kernel.  Decompression speed is relevant at
 118           each boot. Also the memory usage during decompression may become
 119           relevant on memory constrained systems. This is usually based on the
 120           dictionary size of the algorithm with algorithms like XZ and LZMA
 121           featuring large dictionary sizes.
 122
 123           High compression options are mostly useful for users who are
 124           low on RAM, since it reduces the memory consumption during
 125           boot.
 126
 127           Keep in mind that your build system needs to provide the appropriate
 128           compression tool to compress the generated initram cpio file for
 129           embedding.
 130
 131           If in doubt, select 'None'
 132
 133 config INITRAMFS_COMPRESSION_NONE
 134         bool "None"
 135         help
 136           Do not compress the built-in initramfs at all. This may sound wasteful
 137           in space, but, you should be aware that the built-in initramfs will be
 138           compressed at a later stage anyways along with the rest of the kernel,
 139           on those architectures that support this. However, not compressing the
 140           initramfs may lead to slightly higher memory consumption during a
 141           short time at boot, while both the cpio image and the unpacked
 142           filesystem image will be present in memory simultaneously
 143
 144 config INITRAMFS_COMPRESSION_GZIP
 145         bool "Gzip"
 146         depends on RD_GZIP
 147         help
 148           Use the old and well tested gzip compression algorithm. Gzip provides
 149           a good balance between compression ratio and decompression speed and
 150           has a reasonable compression speed. It is also more likely to be
 151           supported by your build system as the gzip tool is present by default
 152           on most distros.
 153
 154 config INITRAMFS_COMPRESSION_BZIP2
 155         bool "Bzip2"
 156         depends on RD_BZIP2
 157         help
 158           It's compression ratio and speed is intermediate. Decompression speed
 159           is slowest among the choices. The initramfs size is about 10% smaller
 160           with bzip2, in comparison to gzip. Bzip2 uses a large amount of
 161           memory. For modern kernels you will need at least 8MB RAM or more for
 162           booting.
 163
 164           If you choose this, keep in mind that you need to have the bzip2 tool
 165           available to be able to compress the initram.
 166
 167 config INITRAMFS_COMPRESSION_LZMA
 168         bool "LZMA"
 169         depends on RD_LZMA
 170         help
 171           This algorithm's compression ratio is best but has a large dictionary
 172           size which might cause issues in memory constrained systems.
 173           Decompression speed is between the other choices. Compression is
 174           slowest. The initramfs size is about 33% smaller with LZMA in
 175           comparison to gzip.
 176
 177           If you choose this, keep in mind that you may need to install the xz
 178           or lzma tools to be able to compress the initram.
 179
 180 config INITRAMFS_COMPRESSION_XZ
 181         bool "XZ"
 182         depends on RD_XZ
 183         help
 184           XZ uses the LZMA2 algorithm and has a large dictionary which may cause
 185           problems on memory constrained systems. The initramfs size is about
 186           30% smaller with XZ in comparison to gzip. Decompression speed is
 187           better than that of bzip2 but worse than gzip and LZO. Compression is
 188           slow.
 189
 190           If you choose this, keep in mind that you may need to install the xz
 191           tool to be able to compress the initram.
 192
 193 config INITRAMFS_COMPRESSION_LZO
 194         bool "LZO"
 195         depends on RD_LZO
 196         help
 197           It's compression ratio is the second poorest amongst the choices. The
 198           kernel size is about 10% bigger than gzip. Despite that, it's
 199           decompression speed is the second fastest and it's compression speed
 200           is quite fast too.
 201
 202           If you choose this, keep in mind that you may need to install the lzop
 203           tool to be able to compress the initram.
 204
 205 config INITRAMFS_COMPRESSION_LZ4
 206         bool "LZ4"
 207         depends on RD_LZ4
 208         help
 209           It's compression ratio is the poorest amongst the choices. The kernel
 210           size is about 15% bigger than gzip; however its decompression speed
 211           is the fastest.
 212
 213           If you choose this, keep in mind that most distros don't provide lz4
 214           by default which could cause a build failure.
 215
 216 endchoice
 217
 218 config INITRAMFS_COMPRESSION
 219         depends on INITRAMFS_SOURCE!=""
 220         string
 221         default ""      if INITRAMFS_COMPRESSION_NONE
 222         default ".gz"   if INITRAMFS_COMPRESSION_GZIP
 223         default ".bz2"  if INITRAMFS_COMPRESSION_BZIP2
 224         default ".lzma" if INITRAMFS_COMPRESSION_LZMA
 225         default ".xz"   if INITRAMFS_COMPRESSION_XZ
 226         default ".lzo"  if INITRAMFS_COMPRESSION_LZO
 227         default ".lz4"  if INITRAMFS_COMPRESSION_LZ4
 228         default ".gz"   if RD_GZIP
 229         default ".lz4"  if RD_LZ4
 230         default ".lzo"  if RD_LZO
 231         default ".xz"   if RD_XZ
 232         default ".lzma" if RD_LZMA
 233         default ".bz2"  if RD_BZIP2
 234         default ""