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 choice
  94         prompt "Built-in initramfs compression mode" if INITRAMFS_SOURCE!=""
  95         help
  96           This option decides by which algorithm the builtin initramfs
  97           will be compressed.  Several compression algorithms are
  98           available, which differ in efficiency, compression and
  99           decompression speed.  Compression speed is only relevant
 100           when building a kernel.  Decompression speed is relevant at
 101           each boot.
 102
 103           If you have any problems with bzip2 or LZMA compressed
 104           initramfs, mail me (Alain Knaff) <alain@knaff.lu>.
 105
 106           High compression options are mostly useful for users who are
 107           low on RAM, since it reduces the memory consumption during
 108           boot.
 109
 110           If in doubt, select 'gzip'
 111
 112 config INITRAMFS_COMPRESSION_NONE
 113         bool "None"
 114         help
 115           Do not compress the built-in initramfs at all. This may
 116           sound wasteful in space, but, you should be aware that the
 117           built-in initramfs will be compressed at a later stage
 118           anyways along with the rest of the kernel, on those
 119           architectures that support this.
 120           However, not compressing the initramfs may lead to slightly
 121           higher memory consumption during a short time at boot, while
 122           both the cpio image and the unpacked filesystem image will
 123           be present in memory simultaneously
 124
 125 config INITRAMFS_COMPRESSION_GZIP
 126         bool "Gzip"
 127         depends on RD_GZIP
 128         help
 129           The old and tried gzip compression. It provides a good balance
 130           between compression ratio and decompression speed.
 131
 132 config INITRAMFS_COMPRESSION_BZIP2
 133         bool "Bzip2"
 134         depends on RD_BZIP2
 135         help
 136           Its compression ratio and speed is intermediate.
 137           Decompression speed is slowest among the choices.  The initramfs
 138           size is about 10% smaller with bzip2, in comparison to gzip.
 139           Bzip2 uses a large amount of memory. For modern kernels you
 140           will need at least 8MB RAM or more for booting.
 141
 142 config INITRAMFS_COMPRESSION_LZMA
 143         bool "LZMA"
 144         depends on RD_LZMA
 145         help
 146           This algorithm's compression ratio is best.
 147           Decompression speed is between the other choices.
 148           Compression is slowest. The initramfs size is about 33%
 149           smaller with LZMA in comparison to gzip.
 150
 151 config INITRAMFS_COMPRESSION_XZ
 152         bool "XZ"
 153         depends on RD_XZ
 154         help
 155           XZ uses the LZMA2 algorithm. The initramfs size is about 30%
 156           smaller with XZ in comparison to gzip. Decompression speed
 157           is better than that of bzip2 but worse than gzip and LZO.
 158           Compression is slow.
 159
 160 config INITRAMFS_COMPRESSION_LZO
 161         bool "LZO"
 162         depends on RD_LZO
 163         help
 164           Its compression ratio is the poorest among the choices. The kernel
 165           size is about 10% bigger than gzip; however its speed
 166           (both compression and decompression) is the fastest.
 167
 168 endchoice