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 choice
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
94 config 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
107 config 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
115 config 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
125 config 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
134 endchoice
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