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1#
2# Configuration for initramfs
3#
4
5config 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
24config 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
36config 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
48config 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
57config 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
66config 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
75config 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
84config 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
93config RD_LZ4
94 bool "Support initial ramdisks compressed using LZ4" if EXPERT
95 default !EXPERT
96 depends on BLK_DEV_INITRD
97 select DECOMPRESS_LZ4
98 help
99 Support loading of a LZ4 encoded initial ramdisk or cpio buffer
100 If unsure, say N.
101
102choice
103 prompt "Built-in initramfs compression mode" if INITRAMFS_SOURCE!=""
104 help
105 This option decides by which algorithm the builtin initramfs
106 will be compressed. Several compression algorithms are
107 available, which differ in efficiency, compression and
108 decompression speed. Compression speed is only relevant
109 when building a kernel. Decompression speed is relevant at
110 each boot.
111
112 If you have any problems with bzip2 or LZMA compressed
113 initramfs, mail me (Alain Knaff) <alain@knaff.lu>.
114
115 High compression options are mostly useful for users who are
116 low on RAM, since it reduces the memory consumption during
117 boot.
118
119 If in doubt, select 'gzip'
120
121config INITRAMFS_COMPRESSION_NONE
122 bool "None"
123 help
124 Do not compress the built-in initramfs at all. This may
125 sound wasteful in space, but, you should be aware that the
126 built-in initramfs will be compressed at a later stage
127 anyways along with the rest of the kernel, on those
128 architectures that support this.
129 However, not compressing the initramfs may lead to slightly
130 higher memory consumption during a short time at boot, while
131 both the cpio image and the unpacked filesystem image will
132 be present in memory simultaneously
133
134config INITRAMFS_COMPRESSION_GZIP
135 bool "Gzip"
136 depends on RD_GZIP
137 help
138 The old and tried gzip compression. It provides a good balance
139 between compression ratio and decompression speed.
140
141config INITRAMFS_COMPRESSION_BZIP2
142 bool "Bzip2"
143 depends on RD_BZIP2
144 help
145 Its compression ratio and speed is intermediate.
146 Decompression speed is slowest among the choices. The initramfs
147 size is about 10% smaller with bzip2, in comparison to gzip.
148 Bzip2 uses a large amount of memory. For modern kernels you
149 will need at least 8MB RAM or more for booting.
150
151config INITRAMFS_COMPRESSION_LZMA
152 bool "LZMA"
153 depends on RD_LZMA
154 help
155 This algorithm's compression ratio is best.
156 Decompression speed is between the other choices.
157 Compression is slowest. The initramfs size is about 33%
158 smaller with LZMA in comparison to gzip.
159
160config INITRAMFS_COMPRESSION_XZ
161 bool "XZ"
162 depends on RD_XZ
163 help
164 XZ uses the LZMA2 algorithm. The initramfs size is about 30%
165 smaller with XZ in comparison to gzip. Decompression speed
166 is better than that of bzip2 but worse than gzip and LZO.
167 Compression is slow.
168
169config INITRAMFS_COMPRESSION_LZO
170 bool "LZO"
171 depends on RD_LZO
172 help
173 Its compression ratio is the poorest among the choices. The kernel
174 size is about 10% bigger than gzip; however its speed
175 (both compression and decompression) is the fastest.
176
177endchoice