1
2
3
4
5
6config INITRAMFS_SOURCE
7 string "Initramfs source file(s)"
8 default ""
9 help
10 This can be either a single cpio archive with a .cpio suffix or a
11 space-separated list of directories and files for building the
12 initramfs image. A cpio archive should contain a filesystem archive
13 to be used as an initramfs image. Directories should contain a
14 filesystem layout to be included in the initramfs image. Files
15 should contain entries according to the format described by the
16 "usr/gen_init_cpio" program in the kernel tree.
17
18 When multiple directories and files are specified then the
19 initramfs image will be the aggregate of all of them.
20
21 See <file:Documentation/early-userspace/README> for more details.
22
23 If you are not sure, leave it blank.
24
25config INITRAMFS_FORCE
26 bool "Ignore the initramfs passed by the bootloader"
27 depends on CMDLINE_EXTEND || CMDLINE_FORCE
28 help
29 This option causes the kernel to ignore the initramfs image
30 (or initrd image) passed to it by the bootloader. This is
31 analogous to CMDLINE_FORCE, which is found on some architectures,
32 and is useful if you cannot or don't want to change the image
33 your bootloader passes to the kernel.
34
35config INITRAMFS_ROOT_UID
36 int "User ID to map to 0 (user root)"
37 depends on INITRAMFS_SOURCE!=""
38 default "0"
39 help
40 If INITRAMFS_SOURCE points to a directory, files owned by this UID
41 (-1 = current user) will be owned by root in the resulting image.
42
43 If you are not sure, leave it set to "0".
44
45config INITRAMFS_ROOT_GID
46 int "Group ID to map to 0 (group root)"
47 depends on INITRAMFS_SOURCE!=""
48 default "0"
49 help
50 If INITRAMFS_SOURCE points to a directory, files owned by this GID
51 (-1 = current group) will be owned by root in the resulting image.
52
53 If you are not sure, leave it set to "0".
54
55config RD_GZIP
56 bool "Support initial ramdisk/ramfs compressed using gzip"
57 depends on BLK_DEV_INITRD
58 default y
59 select DECOMPRESS_GZIP
60 help
61 Support loading of a gzip encoded initial ramdisk or cpio buffer.
62 If unsure, say Y.
63
64config RD_BZIP2
65 bool "Support initial ramdisk/ramfs compressed using bzip2"
66 default y
67 depends on BLK_DEV_INITRD
68 select DECOMPRESS_BZIP2
69 help
70 Support loading of a bzip2 encoded initial ramdisk or cpio buffer
71 If unsure, say N.
72
73config RD_LZMA
74 bool "Support initial ramdisk/ramfs compressed using LZMA"
75 default y
76 depends on BLK_DEV_INITRD
77 select DECOMPRESS_LZMA
78 help
79 Support loading of a LZMA encoded initial ramdisk or cpio buffer
80 If unsure, say N.
81
82config RD_XZ
83 bool "Support initial ramdisk/ramfs compressed using XZ"
84 depends on BLK_DEV_INITRD
85 default y
86 select DECOMPRESS_XZ
87 help
88 Support loading of a XZ encoded initial ramdisk or cpio buffer.
89 If unsure, say N.
90
91config RD_LZO
92 bool "Support initial ramdisk/ramfs compressed using LZO"
93 default y
94 depends on BLK_DEV_INITRD
95 select DECOMPRESS_LZO
96 help
97 Support loading of a LZO encoded initial ramdisk or cpio buffer
98 If unsure, say N.
99
100config RD_LZ4
101 bool "Support initial ramdisk/ramfs compressed using LZ4"
102 default y
103 depends on BLK_DEV_INITRD
104 select DECOMPRESS_LZ4
105 help
106 Support loading of a LZ4 encoded initial ramdisk or cpio buffer
107 If unsure, say N.
108
109choice
110 prompt "Built-in initramfs compression mode"
111 depends on INITRAMFS_SOURCE!=""
112 optional
113 help
114 This option allows you to decide by which algorithm the builtin
115 initramfs will be compressed. Several compression algorithms are
116 available, which differ in efficiency, compression and
117 decompression speed. Compression speed is only relevant
118 when building a kernel. Decompression speed is relevant at
119 each boot. Also the memory usage during decompression may become
120 relevant on memory constrained systems. This is usually based on the
121 dictionary size of the algorithm with algorithms like XZ and LZMA
122 featuring large dictionary sizes.
123
124 High compression options are mostly useful for users who are
125 low on RAM, since it reduces the memory consumption during
126 boot.
127
128 Keep in mind that your build system needs to provide the appropriate
129 compression tool to compress the generated initram cpio file for
130 embedding.
131
132 If in doubt, select 'None'
133
134config INITRAMFS_COMPRESSION_NONE
135 bool "None"
136 help
137 Do not compress the built-in initramfs at all. This may sound wasteful
138 in space, but, you should be aware that the built-in initramfs will be
139 compressed at a later stage anyways along with the rest of the kernel,
140 on those architectures that support this. However, not compressing the
141 initramfs may lead to slightly higher memory consumption during a
142 short time at boot, while both the cpio image and the unpacked
143 filesystem image will be present in memory simultaneously
144
145config INITRAMFS_COMPRESSION_GZIP
146 bool "Gzip"
147 depends on RD_GZIP
148 help
149 Use the old and well tested gzip compression algorithm. Gzip provides
150 a good balance between compression ratio and decompression speed and
151 has a reasonable compression speed. It is also more likely to be
152 supported by your build system as the gzip tool is present by default
153 on most distros.
154
155config INITRAMFS_COMPRESSION_BZIP2
156 bool "Bzip2"
157 depends on RD_BZIP2
158 help
159 It's compression ratio and speed is intermediate. Decompression speed
160 is slowest among the choices. The initramfs size is about 10% smaller
161 with bzip2, in comparison to gzip. Bzip2 uses a large amount of
162 memory. For modern kernels you will need at least 8MB RAM or more for
163 booting.
164
165 If you choose this, keep in mind that you need to have the bzip2 tool
166 available to be able to compress the initram.
167
168config INITRAMFS_COMPRESSION_LZMA
169 bool "LZMA"
170 depends on RD_LZMA
171 help
172 This algorithm's compression ratio is best but has a large dictionary
173 size which might cause issues in memory constrained systems.
174 Decompression speed is between the other choices. Compression is
175 slowest. The initramfs size is about 33% smaller with LZMA in
176 comparison to gzip.
177
178 If you choose this, keep in mind that you may need to install the xz
179 or lzma tools to be able to compress the initram.
180
181config INITRAMFS_COMPRESSION_XZ
182 bool "XZ"
183 depends on RD_XZ
184 help
185 XZ uses the LZMA2 algorithm and has a large dictionary which may cause
186 problems on memory constrained systems. The initramfs size is about
187 30% smaller with XZ in comparison to gzip. Decompression speed is
188 better than that of bzip2 but worse than gzip and LZO. Compression is
189 slow.
190
191 If you choose this, keep in mind that you may need to install the xz
192 tool to be able to compress the initram.
193
194config INITRAMFS_COMPRESSION_LZO
195 bool "LZO"
196 depends on RD_LZO
197 help
198 It's compression ratio is the second poorest amongst the choices. The
199 kernel size is about 10% bigger than gzip. Despite that, it's
200 decompression speed is the second fastest and it's compression speed
201 is quite fast too.
202
203 If you choose this, keep in mind that you may need to install the lzop
204 tool to be able to compress the initram.
205
206config INITRAMFS_COMPRESSION_LZ4
207 bool "LZ4"
208 depends on RD_LZ4
209 help
210 It's compression ratio is the poorest amongst the choices. The kernel
211 size is about 15% bigger than gzip; however its decompression speed
212 is the fastest.
213
214 If you choose this, keep in mind that most distros don't provide lz4
215 by default which could cause a build failure.
216
217endchoice
218
219config INITRAMFS_COMPRESSION
220 depends on INITRAMFS_SOURCE!=""
221 string
222 default "" if INITRAMFS_COMPRESSION_NONE
223 default ".gz" if INITRAMFS_COMPRESSION_GZIP
224 default ".bz2" if INITRAMFS_COMPRESSION_BZIP2
225 default ".lzma" if INITRAMFS_COMPRESSION_LZMA
226 default ".xz" if INITRAMFS_COMPRESSION_XZ
227 default ".lzo" if INITRAMFS_COMPRESSION_LZO
228 default ".lz4" if INITRAMFS_COMPRESSION_LZ4
229 default ".gz" if RD_GZIP
230 default ".lz4" if RD_LZ4
231 default ".lzo" if RD_LZO
232 default ".xz" if RD_XZ
233 default ".lzma" if RD_LZMA
234 default ".bz2" if RD_BZIP2
235 default ""
236
