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_ROOT_UID
  25         int "User ID to map to 0 (user root)"
  26         depends on INITRAMFS_SOURCE!=""
  27         default "0"
  28         help
  29           This setting is only meaningful if the INITRAMFS_SOURCE is
  30           contains a directory.  Setting this user ID (UID) to something
  31           other than "0" will cause all files owned by that UID to be
  32           owned by user root in the initial ramdisk image.
  33
  34           If you are not sure, leave it set to "0".
  35
  36 config INITRAMFS_ROOT_GID
  37         int "Group ID to map to 0 (group root)"
  38         depends on INITRAMFS_SOURCE!=""
  39         default "0"
  40         help
  41           This setting is only meaningful if the INITRAMFS_SOURCE is
  42           contains a directory.  Setting this group ID (GID) to something
  43           other than "0" will cause all files owned by that GID to be
  44           owned by group root in the initial ramdisk image.
  45
  46           If you are not sure, leave it set to "0".
  47
  48 config RD_GZIP
  49         bool "Support initial ramdisks compressed using gzip" if EXPERT
  50         default y
  51         depends on BLK_DEV_INITRD
  52         select DECOMPRESS_GZIP
  53         help
  54           Support loading of a gzip encoded initial ramdisk or cpio buffer.
  55           If unsure, say Y.
  56
  57 config RD_BZIP2
  58         bool "Support initial ramdisks compressed using bzip2" if EXPERT
  59         default !EXPERT
  60         depends on BLK_DEV_INITRD
  61         select DECOMPRESS_BZIP2
  62         help
  63           Support loading of a bzip2 encoded initial ramdisk or cpio buffer
  64           If unsure, say N.
  65
  66 config RD_LZMA
  67         bool "Support initial ramdisks compressed using LZMA" if EXPERT
  68         default !EXPERT
  69         depends on BLK_DEV_INITRD
  70         select DECOMPRESS_LZMA
  71         help
  72           Support loading of a LZMA encoded initial ramdisk or cpio buffer
  73           If unsure, say N.
  74
  75 config RD_XZ
  76         bool "Support initial ramdisks compressed using XZ" if EXPERT
  77         default !EXPERT
  78         depends on BLK_DEV_INITRD
  79         select DECOMPRESS_XZ
  80         help
  81           Support loading of a XZ encoded initial ramdisk or cpio buffer.
  82           If unsure, say N.
  83
  84 config RD_LZO
  85         bool "Support initial ramdisks compressed using LZO" if EXPERT
  86         default !EXPERT
  87         depends on BLK_DEV_INITRD
  88         select DECOMPRESS_LZO
  89         help
  90           Support loading of a LZO encoded initial ramdisk or cpio buffer
  91           If unsure, say N.
  92
  93 config RD_LZ4
  94         bool "Support initial ramdisks compressed using LZ4" if EXPERT
  95         default !EXPERT
  96         depends on BLK_DEV_INITRD
  97         select DECOMPRESS_LZ4
  98         help
  99           Support loading of a LZ4 encoded initial ramdisk or cpio buffer
 100           If unsure, say N.
 101
 102 choice
 103         prompt "Built-in initramfs compression mode" if INITRAMFS_SOURCE!=""
 104         help
 105           This option decides by which algorithm the builtin initramfs
 106           will be compressed.  Several compression algorithms are
 107           available, which differ in efficiency, compression and
 108           decompression speed.  Compression speed is only relevant
 109           when building a kernel.  Decompression speed is relevant at
 110           each boot.
 111
 112           If you have any problems with bzip2 or LZMA compressed
 113           initramfs, mail me (Alain Knaff) <alain@knaff.lu>.
 114
 115           High compression options are mostly useful for users who are
 116           low on RAM, since it reduces the memory consumption during
 117           boot.
 118
 119           If in doubt, select 'gzip'
 120
 121 config INITRAMFS_COMPRESSION_NONE
 122         bool "None"
 123         help
 124           Do not compress the built-in initramfs at all. This may
 125           sound wasteful in space, but, you should be aware that the
 126           built-in initramfs will be compressed at a later stage
 127           anyways along with the rest of the kernel, on those
 128           architectures that support this.
 129           However, not compressing the initramfs may lead to slightly
 130           higher memory consumption during a short time at boot, while
 131           both the cpio image and the unpacked filesystem image will
 132           be present in memory simultaneously
 133
 134 config INITRAMFS_COMPRESSION_GZIP
 135         bool "Gzip"
 136         depends on RD_GZIP
 137         help
 138           The old and tried gzip compression. It provides a good balance
 139           between compression ratio and decompression speed.
 140
 141 config INITRAMFS_COMPRESSION_BZIP2
 142         bool "Bzip2"
 143         depends on RD_BZIP2
 144         help
 145           Its compression ratio and speed is intermediate.
 146           Decompression speed is slowest among the choices.  The initramfs
 147           size is about 10% smaller with bzip2, in comparison to gzip.
 148           Bzip2 uses a large amount of memory. For modern kernels you
 149           will need at least 8MB RAM or more for booting.
 150
 151 config INITRAMFS_COMPRESSION_LZMA
 152         bool "LZMA"
 153         depends on RD_LZMA
 154         help
 155           This algorithm's compression ratio is best.
 156           Decompression speed is between the other choices.
 157           Compression is slowest. The initramfs size is about 33%
 158           smaller with LZMA in comparison to gzip.
 159
 160 config INITRAMFS_COMPRESSION_XZ
 161         bool "XZ"
 162         depends on RD_XZ
 163         help
 164           XZ uses the LZMA2 algorithm. The initramfs size is about 30%
 165           smaller with XZ in comparison to gzip. Decompression speed
 166           is better than that of bzip2 but worse than gzip and LZO.
 167           Compression is slow.
 168
 169 config INITRAMFS_COMPRESSION_LZO
 170         bool "LZO"
 171         depends on RD_LZO
 172         help
 173           Its compression ratio is the poorest among the choices. The kernel
 174           size is about 10% bigger than gzip; however its speed
 175           (both compression and decompression) is the fastest.
 176
 177 endchoice