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 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
  57 config 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
  66 config 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
  75 if INITRAMFS_SOURCE!=""
  76
  77 choice
  78         prompt "Built-in initramfs compression mode"
  79         help
  80           This option decides by which algorithm the builtin initramfs
  81           will be compressed.  Several compression algorithms are
  82           available, which differ in efficiency, compression and
  83           decompression speed.  Compression speed is only relevant
  84           when building a kernel.  Decompression speed is relevant at
  85           each boot.
  86
  87           If you have any problems with bzip2 or LZMA compressed
  88           initramfs, mail me (Alain Knaff) <alain@knaff.lu>.
  89
  90           High compression options are mostly useful for users who are
  91           low on RAM, since it reduces the memory consumption during
  92           boot.
  93
  94           If in doubt, select 'gzip'
  95
  96 config INITRAMFS_COMPRESSION_NONE
  97         bool "None"
  98         help
  99           Do not compress the built-in initramfs at all. This may
 100           sound wasteful in space, but, you should be aware that the
 101           built-in initramfs will be compressed at a later stage
 102           anyways along with the rest of the kernel, on those
 103           architectures that support this.
 104           However, not compressing the initramfs may lead to slightly
 105           higher memory consumption during a short time at boot, while
 106           both the cpio image and the unpacked filesystem image will
 107           be present in memory simultaneously
 108
 109 config INITRAMFS_COMPRESSION_GZIP
 110         bool "Gzip"
 111         depends on RD_GZIP
 112         help
 113           The old and tried gzip compression. Its compression ratio is
 114           the poorest among the 3 choices; however its speed (both
 115           compression and decompression) is the fastest.
 116
 117 config INITRAMFS_COMPRESSION_BZIP2
 118         bool "Bzip2"
 119         depends on RD_BZIP2
 120         help
 121           Its compression ratio and speed is intermediate.
 122           Decompression speed is slowest among the three.  The initramfs
 123           size is about 10% smaller with bzip2, in comparison to gzip.
 124           Bzip2 uses a large amount of memory. For modern kernels you
 125           will need at least 8MB RAM or more for booting.
 126
 127 config INITRAMFS_COMPRESSION_LZMA
 128         bool "LZMA"
 129         depends on RD_LZMA
 130         help
 131           The most recent compression algorithm.
 132           Its ratio is best, decompression speed is between the other
 133           two. Compression is slowest.  The initramfs size is about 33%
 134           smaller with LZMA in comparison to gzip.
 135
 136 endchoice
 137
 138 endif
 139
 140 if INITRAMFS_SOURCE=""
 141 # The builtin initramfs is so small so we don't want to bug the user...
 142
 143 config INITRAMFS_COMPRESSION_NONE
 144         bool
 145         default y
 146
 147 endif