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" if EMBEDDED
57 default y 50 default y
>> 51 depends on BLK_DEV_INITRD
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" if EMBEDDED
65 default y !! 59 default !EMBEDDED
>> 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" if EMBEDDED
73 default y !! 68 default !EMBEDDED
>> 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 <<
80 bool "Support initial ramdisk/ramfs co <<
81 default y <<
82 select DECOMPRESS_XZ <<
83 help <<
84 Support loading of a XZ encoded init <<
85 If unsure, say N. <<
86 <<
87 config RD_LZO <<
88 bool "Support initial ramdisk/ramfs co <<
89 default y <<
90 select DECOMPRESS_LZO <<
91 help <<
92 Support loading of a LZO encoded ini <<
93 If unsure, say N. <<
94 <<
95 config RD_LZ4 <<
96 bool "Support initial ramdisk/ramfs co <<
97 default y <<
98 select DECOMPRESS_LZ4 <<
99 help <<
100 Support loading of a LZ4 encoded ini <<
101 If unsure, say N. <<
102 <<
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 75 choice
112 prompt "Built-in initramfs compression !! 76 prompt "Built-in initramfs compression mode" if INITRAMFS_SOURCE!=""
113 depends on INITRAMFS_SOURCE != "" <<
114 help 77 help
115 This option allows you to decide by !! 78 This option decides by which algorithm the builtin initramfs
116 initramfs will be compressed. Sever !! 79 will be compressed. Several compression algorithms are
117 available, which differ in efficienc 80 available, which differ in efficiency, compression and
118 decompression speed. Compression sp 81 decompression speed. Compression speed is only relevant
119 when building a kernel. Decompressi 82 when building a kernel. Decompression speed is relevant at
120 each boot. Also the memory usage dur !! 83 each boot.
121 relevant on memory constrained syste !! 84
122 dictionary size of the algorithm wit !! 85 If you have any problems with bzip2 or LZMA compressed
123 featuring large dictionary sizes. !! 86 initramfs, mail me (Alain Knaff) <alain@knaff.lu>.
124 87
125 High compression options are mostly 88 High compression options are mostly useful for users who are
126 low on RAM, since it reduces the mem 89 low on RAM, since it reduces the memory consumption during
127 boot. 90 boot.
128 91
129 Keep in mind that your build system !! 92 If in doubt, select 'gzip'
130 compression tool to compress the gen <<
131 embedding. <<
132 93
133 If in doubt, select 'None' !! 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
134 106
135 config INITRAMFS_COMPRESSION_GZIP 107 config INITRAMFS_COMPRESSION_GZIP
136 bool "Gzip" 108 bool "Gzip"
137 depends on RD_GZIP 109 depends on RD_GZIP
138 help 110 help
139 Use the old and well tested gzip com !! 111 The old and tried gzip compression. Its compression ratio is
140 a good balance between compression r !! 112 the poorest among the 3 choices; however its speed (both
141 has a reasonable compression speed. !! 113 compression and decompression) is the fastest.
142 supported by your build system as th <<
143 on most distros. <<
144 114
145 config INITRAMFS_COMPRESSION_BZIP2 115 config INITRAMFS_COMPRESSION_BZIP2
146 bool "Bzip2" 116 bool "Bzip2"
147 depends on RD_BZIP2 117 depends on RD_BZIP2
148 help 118 help
149 It's compression ratio and speed is !! 119 Its compression ratio and speed is intermediate.
150 is slowest among the choices. The in !! 120 Decompression speed is slowest among the three. The initramfs
151 with bzip2, in comparison to gzip. B !! 121 size is about 10% smaller with bzip2, in comparison to gzip.
152 memory. For modern kernels you will !! 122 Bzip2 uses a large amount of memory. For modern kernels you
153 booting. !! 123 will need at least 8MB RAM or more for booting.
154 <<
155 If you choose this, keep in mind tha <<
156 available to be able to compress the <<
157 124
158 config INITRAMFS_COMPRESSION_LZMA 125 config INITRAMFS_COMPRESSION_LZMA
159 bool "LZMA" 126 bool "LZMA"
160 depends on RD_LZMA 127 depends on RD_LZMA
161 help 128 help
162 This algorithm's compression ratio i !! 129 The most recent compression algorithm.
163 size which might cause issues in mem !! 130 Its ratio is best, decompression speed is between the other
164 Decompression speed is between the o !! 131 two. Compression is slowest. The initramfs size is about 33%
165 slowest. The initramfs size is about !! 132 smaller with LZMA in comparison to gzip.
166 comparison to gzip. <<
167 <<
168 If you choose this, keep in mind tha <<
169 or lzma tools to be able to compress <<
170 <<
171 config INITRAMFS_COMPRESSION_XZ <<
172 bool "XZ" <<
173 depends on RD_XZ <<
174 help <<
175 XZ uses the LZMA2 algorithm and has <<
176 problems on memory constrained syste <<
177 30% smaller with XZ in comparison to <<
178 better than that of bzip2 but worse <<
179 slow. <<
180 <<
181 If you choose this, keep in mind tha <<
182 tool to be able to compress the init <<
183 <<
184 config INITRAMFS_COMPRESSION_LZO <<
185 bool "LZO" <<
186 depends on RD_LZO <<
187 help <<
188 Its compression ratio is the second <<
189 kernel size is about 10% bigger than <<
190 decompression speed is the second fa <<
191 is quite fast too. <<
192 <<
193 If you choose this, keep in mind tha <<
194 tool to be able to compress the init <<
195 <<
196 config INITRAMFS_COMPRESSION_LZ4 <<
197 bool "LZ4" <<
198 depends on RD_LZ4 <<
199 help <<
200 It's compression ratio is the poores <<
201 size is about 15% bigger than gzip; <<
202 is the fastest. <<
203 <<
204 If you choose this, keep in mind tha <<
205 by default which could cause a build <<
206 <<
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 <<
228 133
229 endchoice 134 endchoice
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