1 # SPDX-License-Identifier: GPL-2.0 <<
2 # 1 #
3 # Configuration for initramfs 2 # Configuration for initramfs
4 # 3 #
5 4
6 config INITRAMFS_SOURCE 5 config INITRAMFS_SOURCE
7 string "Initramfs source file(s)" 6 string "Initramfs source file(s)"
8 default "" 7 default ""
9 help 8 help
10 This can be either a single cpio arc 9 This can be either a single cpio archive with a .cpio suffix or a
11 space-separated list of directories 10 space-separated list of directories and files for building the
12 initramfs image. A cpio archive sho 11 initramfs image. A cpio archive should contain a filesystem archive
13 to be used as an initramfs image. D 12 to be used as an initramfs image. Directories should contain a
14 filesystem layout to be included in 13 filesystem layout to be included in the initramfs image. Files
15 should contain entries according to 14 should contain entries according to the format described by the
16 "usr/gen_init_cpio" program in the k 15 "usr/gen_init_cpio" program in the kernel tree.
17 16
18 When multiple directories and files 17 When multiple directories and files are specified then the
19 initramfs image will be the aggregat 18 initramfs image will be the aggregate of all of them.
20 19
21 See <file:Documentation/driver-api/e !! 20 See <file:Documentation/early-userspace/README> for more details.
22 21
23 If you are not sure, leave it blank. 22 If you are not sure, leave it blank.
24 23
25 config INITRAMFS_FORCE <<
26 bool "Ignore the initramfs passed by t <<
27 depends on CMDLINE_EXTEND || CMDLINE_F <<
28 help <<
29 This option causes the kernel to ign <<
30 (or initrd image) passed to it by th <<
31 analogous to CMDLINE_FORCE, which is <<
32 and is useful if you cannot or don't <<
33 your bootloader passes to the kernel <<
34 <<
35 config INITRAMFS_ROOT_UID 24 config INITRAMFS_ROOT_UID
36 int "User ID to map to 0 (user root)" 25 int "User ID to map to 0 (user root)"
37 depends on INITRAMFS_SOURCE!="" 26 depends on INITRAMFS_SOURCE!=""
38 default "0" 27 default "0"
39 help 28 help
40 If INITRAMFS_SOURCE points to a dire !! 29 This setting is only meaningful if the INITRAMFS_SOURCE is
41 (-1 = current user) will be owned by !! 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.
42 33
43 If you are not sure, leave it set to 34 If you are not sure, leave it set to "0".
44 35
45 config INITRAMFS_ROOT_GID 36 config INITRAMFS_ROOT_GID
46 int "Group ID to map to 0 (group root) 37 int "Group ID to map to 0 (group root)"
47 depends on INITRAMFS_SOURCE!="" 38 depends on INITRAMFS_SOURCE!=""
48 default "0" 39 default "0"
49 help 40 help
50 If INITRAMFS_SOURCE points to a dire !! 41 This setting is only meaningful if the INITRAMFS_SOURCE is
51 (-1 = current group) will be owned b !! 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.
52 45
53 If you are not sure, leave it set to 46 If you are not sure, leave it set to "0".
54 47
55 config RD_GZIP 48 config RD_GZIP
56 bool "Support initial ramdisk/ramfs co !! 49 bool "Support initial ramdisks compressed using gzip"
>> 50 depends on BLK_DEV_INITRD
57 default y 51 default y
58 select DECOMPRESS_GZIP 52 select DECOMPRESS_GZIP
59 help 53 help
60 Support loading of a gzip encoded in 54 Support loading of a gzip encoded initial ramdisk or cpio buffer.
61 If unsure, say Y. 55 If unsure, say Y.
62 56
63 config RD_BZIP2 57 config RD_BZIP2
64 bool "Support initial ramdisk/ramfs co !! 58 bool "Support initial ramdisks compressed using bzip2"
65 default y 59 default y
>> 60 depends on BLK_DEV_INITRD
66 select DECOMPRESS_BZIP2 61 select DECOMPRESS_BZIP2
67 help 62 help
68 Support loading of a bzip2 encoded i 63 Support loading of a bzip2 encoded initial ramdisk or cpio buffer
69 If unsure, say N. 64 If unsure, say N.
70 65
71 config RD_LZMA 66 config RD_LZMA
72 bool "Support initial ramdisk/ramfs co !! 67 bool "Support initial ramdisks compressed using LZMA"
73 default y 68 default y
>> 69 depends on BLK_DEV_INITRD
74 select DECOMPRESS_LZMA 70 select DECOMPRESS_LZMA
75 help 71 help
76 Support loading of a LZMA encoded in 72 Support loading of a LZMA encoded initial ramdisk or cpio buffer
77 If unsure, say N. 73 If unsure, say N.
78 74
79 config RD_XZ 75 config RD_XZ
80 bool "Support initial ramdisk/ramfs co !! 76 bool "Support initial ramdisks compressed using XZ"
>> 77 depends on BLK_DEV_INITRD
81 default y 78 default y
82 select DECOMPRESS_XZ 79 select DECOMPRESS_XZ
83 help 80 help
84 Support loading of a XZ encoded init 81 Support loading of a XZ encoded initial ramdisk or cpio buffer.
85 If unsure, say N. 82 If unsure, say N.
86 83
87 config RD_LZO 84 config RD_LZO
88 bool "Support initial ramdisk/ramfs co !! 85 bool "Support initial ramdisks compressed using LZO"
89 default y 86 default y
>> 87 depends on BLK_DEV_INITRD
90 select DECOMPRESS_LZO 88 select DECOMPRESS_LZO
91 help 89 help
92 Support loading of a LZO encoded ini 90 Support loading of a LZO encoded initial ramdisk or cpio buffer
93 If unsure, say N. 91 If unsure, say N.
94 92
95 config RD_LZ4 93 config RD_LZ4
96 bool "Support initial ramdisk/ramfs co !! 94 bool "Support initial ramdisks compressed using LZ4"
97 default y 95 default y
>> 96 depends on BLK_DEV_INITRD
98 select DECOMPRESS_LZ4 97 select DECOMPRESS_LZ4
99 help 98 help
100 Support loading of a LZ4 encoded ini 99 Support loading of a LZ4 encoded initial ramdisk or cpio buffer
101 If unsure, say N. 100 If unsure, say N.
102 101
103 config RD_ZSTD <<
104 bool "Support initial ramdisk/ramfs co <<
105 default y <<
106 select DECOMPRESS_ZSTD <<
107 help <<
108 Support loading of a ZSTD encoded in <<
109 If unsure, say N. <<
110 <<
111 choice 102 choice
112 prompt "Built-in initramfs compression 103 prompt "Built-in initramfs compression mode"
113 depends on INITRAMFS_SOURCE != "" !! 104 depends on INITRAMFS_SOURCE!=""
>> 105 optional
114 help 106 help
115 This option allows you to decide by 107 This option allows you to decide by which algorithm the builtin
116 initramfs will be compressed. Sever 108 initramfs will be compressed. Several compression algorithms are
117 available, which differ in efficienc 109 available, which differ in efficiency, compression and
118 decompression speed. Compression sp 110 decompression speed. Compression speed is only relevant
119 when building a kernel. Decompressi 111 when building a kernel. Decompression speed is relevant at
120 each boot. Also the memory usage dur 112 each boot. Also the memory usage during decompression may become
121 relevant on memory constrained syste 113 relevant on memory constrained systems. This is usually based on the
122 dictionary size of the algorithm wit 114 dictionary size of the algorithm with algorithms like XZ and LZMA
123 featuring large dictionary sizes. 115 featuring large dictionary sizes.
124 116
125 High compression options are mostly 117 High compression options are mostly useful for users who are
126 low on RAM, since it reduces the mem 118 low on RAM, since it reduces the memory consumption during
127 boot. 119 boot.
128 120
129 Keep in mind that your build system 121 Keep in mind that your build system needs to provide the appropriate
130 compression tool to compress the gen 122 compression tool to compress the generated initram cpio file for
131 embedding. 123 embedding.
132 124
133 If in doubt, select 'None' 125 If in doubt, select 'None'
134 126
>> 127 config INITRAMFS_COMPRESSION_NONE
>> 128 bool "None"
>> 129 help
>> 130 Do not compress the built-in initramfs at all. This may sound wasteful
>> 131 in space, but, you should be aware that the built-in initramfs will be
>> 132 compressed at a later stage anyways along with the rest of the kernel,
>> 133 on those architectures that support this. However, not compressing the
>> 134 initramfs may lead to slightly higher memory consumption during a
>> 135 short time at boot, while both the cpio image and the unpacked
>> 136 filesystem image will be present in memory simultaneously
>> 137
135 config INITRAMFS_COMPRESSION_GZIP 138 config INITRAMFS_COMPRESSION_GZIP
136 bool "Gzip" 139 bool "Gzip"
137 depends on RD_GZIP 140 depends on RD_GZIP
138 help 141 help
139 Use the old and well tested gzip com 142 Use the old and well tested gzip compression algorithm. Gzip provides
140 a good balance between compression r 143 a good balance between compression ratio and decompression speed and
141 has a reasonable compression speed. 144 has a reasonable compression speed. It is also more likely to be
142 supported by your build system as th 145 supported by your build system as the gzip tool is present by default
143 on most distros. 146 on most distros.
144 147
145 config INITRAMFS_COMPRESSION_BZIP2 148 config INITRAMFS_COMPRESSION_BZIP2
146 bool "Bzip2" 149 bool "Bzip2"
147 depends on RD_BZIP2 150 depends on RD_BZIP2
148 help 151 help
149 It's compression ratio and speed is 152 It's compression ratio and speed is intermediate. Decompression speed
150 is slowest among the choices. The in 153 is slowest among the choices. The initramfs size is about 10% smaller
151 with bzip2, in comparison to gzip. B 154 with bzip2, in comparison to gzip. Bzip2 uses a large amount of
152 memory. For modern kernels you will 155 memory. For modern kernels you will need at least 8MB RAM or more for
153 booting. 156 booting.
154 157
155 If you choose this, keep in mind tha 158 If you choose this, keep in mind that you need to have the bzip2 tool
156 available to be able to compress the 159 available to be able to compress the initram.
157 160
158 config INITRAMFS_COMPRESSION_LZMA 161 config INITRAMFS_COMPRESSION_LZMA
159 bool "LZMA" 162 bool "LZMA"
160 depends on RD_LZMA 163 depends on RD_LZMA
161 help 164 help
162 This algorithm's compression ratio i 165 This algorithm's compression ratio is best but has a large dictionary
163 size which might cause issues in mem 166 size which might cause issues in memory constrained systems.
164 Decompression speed is between the o 167 Decompression speed is between the other choices. Compression is
165 slowest. The initramfs size is about 168 slowest. The initramfs size is about 33% smaller with LZMA in
166 comparison to gzip. 169 comparison to gzip.
167 170
168 If you choose this, keep in mind tha 171 If you choose this, keep in mind that you may need to install the xz
169 or lzma tools to be able to compress 172 or lzma tools to be able to compress the initram.
170 173
171 config INITRAMFS_COMPRESSION_XZ 174 config INITRAMFS_COMPRESSION_XZ
172 bool "XZ" 175 bool "XZ"
173 depends on RD_XZ 176 depends on RD_XZ
174 help 177 help
175 XZ uses the LZMA2 algorithm and has 178 XZ uses the LZMA2 algorithm and has a large dictionary which may cause
176 problems on memory constrained syste 179 problems on memory constrained systems. The initramfs size is about
177 30% smaller with XZ in comparison to 180 30% smaller with XZ in comparison to gzip. Decompression speed is
178 better than that of bzip2 but worse 181 better than that of bzip2 but worse than gzip and LZO. Compression is
179 slow. 182 slow.
180 183
181 If you choose this, keep in mind tha 184 If you choose this, keep in mind that you may need to install the xz
182 tool to be able to compress the init 185 tool to be able to compress the initram.
183 186
184 config INITRAMFS_COMPRESSION_LZO 187 config INITRAMFS_COMPRESSION_LZO
185 bool "LZO" 188 bool "LZO"
186 depends on RD_LZO 189 depends on RD_LZO
187 help 190 help
188 Its compression ratio is the second !! 191 It's compression ratio is the second poorest amongst the choices. The
189 kernel size is about 10% bigger than !! 192 kernel size is about 10% bigger than gzip. Despite that, it's
190 decompression speed is the second fa !! 193 decompression speed is the second fastest and it's compression speed
191 is quite fast too. 194 is quite fast too.
192 195
193 If you choose this, keep in mind tha 196 If you choose this, keep in mind that you may need to install the lzop
194 tool to be able to compress the init 197 tool to be able to compress the initram.
195 198
196 config INITRAMFS_COMPRESSION_LZ4 199 config INITRAMFS_COMPRESSION_LZ4
197 bool "LZ4" 200 bool "LZ4"
198 depends on RD_LZ4 201 depends on RD_LZ4
199 help 202 help
200 It's compression ratio is the poores 203 It's compression ratio is the poorest amongst the choices. The kernel
201 size is about 15% bigger than gzip; 204 size is about 15% bigger than gzip; however its decompression speed
202 is the fastest. 205 is the fastest.
203 206
204 If you choose this, keep in mind tha 207 If you choose this, keep in mind that most distros don't provide lz4
205 by default which could cause a build 208 by default which could cause a build failure.
206 209
207 config INITRAMFS_COMPRESSION_ZSTD <<
208 bool "ZSTD" <<
209 depends on RD_ZSTD <<
210 help <<
211 ZSTD is a compression algorithm targ <<
212 with fast decompression speed. It wi <<
213 decompress around the same speed as <<
214 <<
215 If you choose this, keep in mind tha <<
216 tool to be able to compress the init <<
217 <<
218 config INITRAMFS_COMPRESSION_NONE <<
219 bool "None" <<
220 help <<
221 Do not compress the built-in initram <<
222 in space, but, you should be aware t <<
223 compressed at a later stage anyways <<
224 on those architectures that support <<
225 initramfs may lead to slightly highe <<
226 short time at boot, while both the c <<
227 filesystem image will be present in <<
228 <<
229 endchoice 210 endchoice
>> 211
>> 212 config INITRAMFS_COMPRESSION
>> 213 string
>> 214 default "" if INITRAMFS_COMPRESSION_NONE
>> 215 default ".gz" if INITRAMFS_COMPRESSION_GZIP
>> 216 default ".bz2" if INITRAMFS_COMPRESSION_BZIP2
>> 217 default ".lzma" if INITRAMFS_COMPRESSION_LZMA
>> 218 default ".xz" if INITRAMFS_COMPRESSION_XZ
>> 219 default ".lzo" if INITRAMFS_COMPRESSION_LZO
>> 220 default ".lz4" if INITRAMFS_COMPRESSION_LZ4
>> 221 default ".gz" if RD_GZIP
>> 222 default ".lz4" if RD_LZ4
>> 223 default ".lzo" if RD_LZO
>> 224 default ".xz" if RD_XZ
>> 225 default ".lzma" if RD_LZMA
>> 226 default ".bz2" if RD_BZIP2
>> 227 default ""
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