LXR linux/usr/Kconfig

   1#
   2# Configuration for initramfs
   3#
   4
   5config 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
  24config 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
  36config 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
  48config RD_GZIP
  49        bool "Support initial ramdisks compressed using gzip" if EMBEDDED
  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
  57config RD_BZIP2
  58        bool "Support initial ramdisks compressed using bzip2" if EMBEDDED
  59        default !EMBEDDED
  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
  66config RD_LZMA
  67        bool "Support initial ramdisks compressed using LZMA" if EMBEDDED
  68        default !EMBEDDED
  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
  75choice
  76        prompt "Built-in initramfs compression mode" if INITRAMFS_SOURCE!=""
  77        help
  78          This option decides by which algorithm the builtin initramfs
  79          will be compressed.  Several compression algorithms are
  80          available, which differ in efficiency, compression and
  81          decompression speed.  Compression speed is only relevant
  82          when building a kernel.  Decompression speed is relevant at
  83          each boot.
  84
  85          If you have any problems with bzip2 or LZMA compressed
  86          initramfs, mail me (Alain Knaff) <alain@knaff.lu>.
  87
  88          High compression options are mostly useful for users who are
  89          low on RAM, since it reduces the memory consumption during
  90          boot.
  91
  92          If in doubt, select 'gzip'
  93
  94config INITRAMFS_COMPRESSION_NONE
  95        bool "None"
  96        help
  97          Do not compress the built-in initramfs at all. This may
  98          sound wasteful in space, but, you should be aware that the
  99          built-in initramfs will be compressed at a later stage
 100          anyways along with the rest of the kernel, on those
 101          architectures that support this.
 102          However, not compressing the initramfs may lead to slightly
 103          higher memory consumption during a short time at boot, while
 104          both the cpio image and the unpacked filesystem image will
 105          be present in memory simultaneously
 106
 107config INITRAMFS_COMPRESSION_GZIP
 108        bool "Gzip"
 109        depends on RD_GZIP
 110        help
 111          The old and tried gzip compression. Its compression ratio is
 112          the poorest among the 3 choices; however its speed (both
 113          compression and decompression) is the fastest.
 114
 115config INITRAMFS_COMPRESSION_BZIP2
 116        bool "Bzip2"
 117        depends on RD_BZIP2
 118        help
 119          Its compression ratio and speed is intermediate.
 120          Decompression speed is slowest among the three.  The initramfs
 121          size is about 10% smaller with bzip2, in comparison to gzip.
 122          Bzip2 uses a large amount of memory. For modern kernels you
 123          will need at least 8MB RAM or more for booting.
 124
 125config INITRAMFS_COMPRESSION_LZMA
 126        bool "LZMA"
 127        depends on RD_LZMA
 128        help
 129          The most recent compression algorithm.
 130          Its ratio is best, decompression speed is between the other
 131          two. Compression is slowest.  The initramfs size is about 33%
 132          smaller with LZMA in comparison to gzip.
 133
 134endchoice
 135