2 # Configuration for initramfs
5 config INITRAMFS_SOURCE
6 string "Initramfs source file(s)"
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.
17 When multiple directories and files are specified then the
18 initramfs image will be the aggregate of all of them.
20 See <file:Documentation/early-userspace/README> for more details.
22 If you are not sure, leave it blank.
24 config INITRAMFS_ROOT_UID
25 int "User ID to map to 0 (user root)"
26 depends on INITRAMFS_SOURCE!=""
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.
34 If you are not sure, leave it set to "0".
36 config INITRAMFS_ROOT_GID
37 int "Group ID to map to 0 (group root)"
38 depends on INITRAMFS_SOURCE!=""
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.
46 If you are not sure, leave it set to "0".
49 bool "Support initial ramdisks compressed using gzip" if EMBEDDED
51 depends on BLK_DEV_INITRD
52 select DECOMPRESS_GZIP
54 Support loading of a gzip encoded initial ramdisk or cpio buffer.
58 bool "Support initial ramdisks compressed using bzip2" if EMBEDDED
60 depends on BLK_DEV_INITRD
61 select DECOMPRESS_BZIP2
63 Support loading of a bzip2 encoded initial ramdisk or cpio buffer
67 bool "Support initial ramdisks compressed using LZMA" if EMBEDDED
69 depends on BLK_DEV_INITRD
70 select DECOMPRESS_LZMA
72 Support loading of a LZMA encoded initial ramdisk or cpio buffer
75 if INITRAMFS_SOURCE!=""
78 prompt "Built-in initramfs compression mode"
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
87 If you have any problems with bzip2 or LZMA compressed
88 initramfs, mail me (Alain Knaff) <alain@knaff.lu>.
90 High compression options are mostly useful for users who are
91 low on RAM, since it reduces the memory consumption during
94 If in doubt, select 'gzip'
96 config INITRAMFS_COMPRESSION_NONE
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
109 config INITRAMFS_COMPRESSION_GZIP
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.
117 config INITRAMFS_COMPRESSION_BZIP2
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.
127 config INITRAMFS_COMPRESSION_LZMA
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.
140 if INITRAMFS_SOURCE=""
141 # The builtin initramfs is so small so we don't want to bug the user...
143 config INITRAMFS_COMPRESSION_NONE