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 178