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