Kconfig 4.8 KB

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  1. #
  2. # Configuration for initramfs
  3. #
  4. config INITRAMFS_SOURCE
  5. string "Initramfs source file(s)"
  6. default ""
  7. help
  8. This can be either a single cpio archive with a .cpio suffix or a
  9. space-separated list of directories and files for building the
  10. initramfs image. A cpio archive should contain a filesystem archive
  11. to be used as an initramfs image. Directories should contain a
  12. filesystem layout to be included in the initramfs image. Files
  13. should contain entries according to the format described by the
  14. "usr/gen_init_cpio" program in the kernel tree.
  15. When multiple directories and files are specified then the
  16. initramfs image will be the aggregate of all of them.
  17. See <file:Documentation/early-userspace/README> for more details.
  18. If you are not sure, leave it blank.
  19. config INITRAMFS_ROOT_UID
  20. int "User ID to map to 0 (user root)"
  21. depends on INITRAMFS_SOURCE!=""
  22. default "0"
  23. help
  24. This setting is only meaningful if the INITRAMFS_SOURCE is
  25. contains a directory. Setting this user ID (UID) to something
  26. other than "0" will cause all files owned by that UID to be
  27. owned by user root in the initial ramdisk image.
  28. If you are not sure, leave it set to "0".
  29. config INITRAMFS_ROOT_GID
  30. int "Group ID to map to 0 (group root)"
  31. depends on INITRAMFS_SOURCE!=""
  32. default "0"
  33. help
  34. This setting is only meaningful if the INITRAMFS_SOURCE is
  35. contains a directory. Setting this group ID (GID) to something
  36. other than "0" will cause all files owned by that GID to be
  37. owned by group root in the initial ramdisk image.
  38. If you are not sure, leave it set to "0".
  39. config RD_GZIP
  40. bool "Support initial ramdisks compressed using gzip" if EMBEDDED
  41. default y
  42. depends on BLK_DEV_INITRD
  43. select DECOMPRESS_GZIP
  44. help
  45. Support loading of a gzip encoded initial ramdisk or cpio buffer.
  46. If unsure, say Y.
  47. config RD_BZIP2
  48. bool "Support initial ramdisks compressed using bzip2" if EMBEDDED
  49. default !EMBEDDED
  50. depends on BLK_DEV_INITRD
  51. select DECOMPRESS_BZIP2
  52. help
  53. Support loading of a bzip2 encoded initial ramdisk or cpio buffer
  54. If unsure, say N.
  55. config RD_LZMA
  56. bool "Support initial ramdisks compressed using LZMA" if EMBEDDED
  57. default !EMBEDDED
  58. depends on BLK_DEV_INITRD
  59. select DECOMPRESS_LZMA
  60. help
  61. Support loading of a LZMA encoded initial ramdisk or cpio buffer
  62. If unsure, say N.
  63. config RD_LZO
  64. bool "Support initial ramdisks compressed using LZO" if EMBEDDED
  65. default !EMBEDDED
  66. depends on BLK_DEV_INITRD
  67. select DECOMPRESS_LZO
  68. help
  69. Support loading of a LZO encoded initial ramdisk or cpio buffer
  70. If unsure, say N.
  71. choice
  72. prompt "Built-in initramfs compression mode" if INITRAMFS_SOURCE!=""
  73. help
  74. This option decides by which algorithm the builtin initramfs
  75. will be compressed. Several compression algorithms are
  76. available, which differ in efficiency, compression and
  77. decompression speed. Compression speed is only relevant
  78. when building a kernel. Decompression speed is relevant at
  79. each boot.
  80. If you have any problems with bzip2 or LZMA compressed
  81. initramfs, mail me (Alain Knaff) <alain@knaff.lu>.
  82. High compression options are mostly useful for users who are
  83. low on RAM, since it reduces the memory consumption during
  84. boot.
  85. If in doubt, select 'gzip'
  86. config INITRAMFS_COMPRESSION_NONE
  87. bool "None"
  88. help
  89. Do not compress the built-in initramfs at all. This may
  90. sound wasteful in space, but, you should be aware that the
  91. built-in initramfs will be compressed at a later stage
  92. anyways along with the rest of the kernel, on those
  93. architectures that support this.
  94. However, not compressing the initramfs may lead to slightly
  95. higher memory consumption during a short time at boot, while
  96. both the cpio image and the unpacked filesystem image will
  97. be present in memory simultaneously
  98. config INITRAMFS_COMPRESSION_GZIP
  99. bool "Gzip"
  100. depends on RD_GZIP
  101. help
  102. The old and tried gzip compression. It provides a good balance
  103. between compression ratio and decompression speed.
  104. config INITRAMFS_COMPRESSION_BZIP2
  105. bool "Bzip2"
  106. depends on RD_BZIP2
  107. help
  108. Its compression ratio and speed is intermediate.
  109. Decompression speed is slowest among the four. The initramfs
  110. size is about 10% smaller with bzip2, in comparison to gzip.
  111. Bzip2 uses a large amount of memory. For modern kernels you
  112. will need at least 8MB RAM or more for booting.
  113. config INITRAMFS_COMPRESSION_LZMA
  114. bool "LZMA"
  115. depends on RD_LZMA
  116. help
  117. The most recent compression algorithm.
  118. Its ratio is best, decompression speed is between the other
  119. three. Compression is slowest. The initramfs size is about 33%
  120. smaller with LZMA in comparison to gzip.
  121. config INITRAMFS_COMPRESSION_LZO
  122. bool "LZO"
  123. depends on RD_LZO
  124. help
  125. Its compression ratio is the poorest among the four. The kernel
  126. size is about about 10% bigger than gzip; however its speed
  127. (both compression and decompression) is the fastest.
  128. endchoice