diff options
Diffstat (limited to 'usr/Kconfig')
| -rw-r--r-- | usr/Kconfig | 180 |
1 files changed, 116 insertions, 64 deletions
diff --git a/usr/Kconfig b/usr/Kconfig index 642f503d3e9f..9279a2893ab0 100644 --- a/usr/Kconfig +++ b/usr/Kconfig @@ -1,3 +1,4 @@ +# SPDX-License-Identifier: GPL-2.0 # # Configuration for initramfs # @@ -17,19 +18,27 @@ config INITRAMFS_SOURCE When multiple directories and files are specified then the initramfs image will be the aggregate of all of them. - See <file:Documentation/early-userspace/README> for more details. + See <file:Documentation/driver-api/early-userspace/early_userspace_support.rst> for more details. If you are not sure, leave it blank. +config INITRAMFS_FORCE + bool "Ignore the initramfs passed by the bootloader" + depends on CMDLINE_EXTEND || CMDLINE_FORCE + help + This option causes the kernel to ignore the initramfs image + (or initrd image) passed to it by the bootloader. This is + analogous to CMDLINE_FORCE, which is found on some architectures, + and is useful if you cannot or don't want to change the image + your bootloader passes to the kernel. + config INITRAMFS_ROOT_UID int "User ID to map to 0 (user root)" depends on INITRAMFS_SOURCE!="" default "0" help - This setting is only meaningful if the INITRAMFS_SOURCE is - contains a directory. Setting this user ID (UID) to something - other than "0" will cause all files owned by that UID to be - owned by user root in the initial ramdisk image. + If INITRAMFS_SOURCE points to a directory, files owned by this UID + (-1 = current user) will be owned by root in the resulting image. If you are not sure, leave it set to "0". @@ -38,140 +47,183 @@ config INITRAMFS_ROOT_GID depends on INITRAMFS_SOURCE!="" default "0" help - This setting is only meaningful if the INITRAMFS_SOURCE is - contains a directory. Setting this group ID (GID) to something - other than "0" will cause all files owned by that GID to be - owned by group root in the initial ramdisk image. + If INITRAMFS_SOURCE points to a directory, files owned by this GID + (-1 = current group) will be owned by root in the resulting image. If you are not sure, leave it set to "0". config RD_GZIP - bool "Support initial ramdisks compressed using gzip" if EXPERT + bool "Support initial ramdisk/ramfs compressed using gzip" default y - depends on BLK_DEV_INITRD select DECOMPRESS_GZIP help Support loading of a gzip encoded initial ramdisk or cpio buffer. If unsure, say Y. config RD_BZIP2 - bool "Support initial ramdisks compressed using bzip2" if EXPERT - default !EXPERT - depends on BLK_DEV_INITRD + bool "Support initial ramdisk/ramfs compressed using bzip2" + default y select DECOMPRESS_BZIP2 help Support loading of a bzip2 encoded initial ramdisk or cpio buffer If unsure, say N. config RD_LZMA - bool "Support initial ramdisks compressed using LZMA" if EXPERT - default !EXPERT - depends on BLK_DEV_INITRD + bool "Support initial ramdisk/ramfs compressed using LZMA" + default y select DECOMPRESS_LZMA help Support loading of a LZMA encoded initial ramdisk or cpio buffer If unsure, say N. config RD_XZ - bool "Support initial ramdisks compressed using XZ" if EXPERT - default !EXPERT - depends on BLK_DEV_INITRD + bool "Support initial ramdisk/ramfs compressed using XZ" + default y select DECOMPRESS_XZ help Support loading of a XZ encoded initial ramdisk or cpio buffer. If unsure, say N. config RD_LZO - bool "Support initial ramdisks compressed using LZO" if EXPERT - default !EXPERT - depends on BLK_DEV_INITRD + bool "Support initial ramdisk/ramfs compressed using LZO" + default y select DECOMPRESS_LZO help Support loading of a LZO encoded initial ramdisk or cpio buffer If unsure, say N. config RD_LZ4 - bool "Support initial ramdisks compressed using LZ4" if EXPERT - default !EXPERT - depends on BLK_DEV_INITRD + bool "Support initial ramdisk/ramfs compressed using LZ4" + default y select DECOMPRESS_LZ4 help Support loading of a LZ4 encoded initial ramdisk or cpio buffer If unsure, say N. +config RD_ZSTD + bool "Support initial ramdisk/ramfs compressed using ZSTD" + default y + select DECOMPRESS_ZSTD + help + Support loading of a ZSTD encoded initial ramdisk or cpio buffer. + If unsure, say N. + choice - prompt "Built-in initramfs compression mode" if INITRAMFS_SOURCE!="" + prompt "Built-in initramfs compression mode" + depends on INITRAMFS_SOURCE != "" help - This option decides by which algorithm the builtin initramfs - will be compressed. Several compression algorithms are + This option allows you to decide by which algorithm the builtin + initramfs will be compressed. Several compression algorithms are available, which differ in efficiency, compression and decompression speed. Compression speed is only relevant when building a kernel. Decompression speed is relevant at - each boot. - - If you have any problems with bzip2 or LZMA compressed - initramfs, mail me (Alain Knaff) <alain@knaff.lu>. + each boot. Also the memory usage during decompression may become + relevant on memory constrained systems. This is usually based on the + dictionary size of the algorithm with algorithms like XZ and LZMA + featuring large dictionary sizes. High compression options are mostly useful for users who are low on RAM, since it reduces the memory consumption during boot. - If in doubt, select 'gzip' + Keep in mind that your build system needs to provide the appropriate + compression tool to compress the generated initram cpio file for + embedding. -config INITRAMFS_COMPRESSION_NONE - bool "None" - help - Do not compress the built-in initramfs at all. This may - sound wasteful in space, but, you should be aware that the - built-in initramfs will be compressed at a later stage - anyways along with the rest of the kernel, on those - architectures that support this. - However, not compressing the initramfs may lead to slightly - higher memory consumption during a short time at boot, while - both the cpio image and the unpacked filesystem image will - be present in memory simultaneously + If in doubt, select 'None' config INITRAMFS_COMPRESSION_GZIP bool "Gzip" depends on RD_GZIP help - The old and tried gzip compression. It provides a good balance - between compression ratio and decompression speed. + Use the old and well tested gzip compression algorithm. Gzip provides + a good balance between compression ratio and decompression speed and + has a reasonable compression speed. It is also more likely to be + supported by your build system as the gzip tool is present by default + on most distros. config INITRAMFS_COMPRESSION_BZIP2 bool "Bzip2" depends on RD_BZIP2 help - Its compression ratio and speed is intermediate. - Decompression speed is slowest among the choices. The initramfs - size is about 10% smaller with bzip2, in comparison to gzip. - Bzip2 uses a large amount of memory. For modern kernels you - will need at least 8MB RAM or more for booting. + It's compression ratio and speed is intermediate. Decompression speed + is slowest among the choices. The initramfs size is about 10% smaller + with bzip2, in comparison to gzip. Bzip2 uses a large amount of + memory. For modern kernels you will need at least 8MB RAM or more for + booting. + + If you choose this, keep in mind that you need to have the bzip2 tool + available to be able to compress the initram. config INITRAMFS_COMPRESSION_LZMA bool "LZMA" depends on RD_LZMA help - This algorithm's compression ratio is best. - Decompression speed is between the other choices. - Compression is slowest. The initramfs size is about 33% - smaller with LZMA in comparison to gzip. + This algorithm's compression ratio is best but has a large dictionary + size which might cause issues in memory constrained systems. + Decompression speed is between the other choices. Compression is + slowest. The initramfs size is about 33% smaller with LZMA in + comparison to gzip. + + If you choose this, keep in mind that you may need to install the xz + or lzma tools to be able to compress the initram. config INITRAMFS_COMPRESSION_XZ bool "XZ" depends on RD_XZ help - XZ uses the LZMA2 algorithm. The initramfs size is about 30% - smaller with XZ in comparison to gzip. Decompression speed - is better than that of bzip2 but worse than gzip and LZO. - Compression is slow. + XZ uses the LZMA2 algorithm and has a large dictionary which may cause + problems on memory constrained systems. The initramfs size is about + 30% smaller with XZ in comparison to gzip. Decompression speed is + better than that of bzip2 but worse than gzip and LZO. Compression is + slow. + + If you choose this, keep in mind that you may need to install the xz + tool to be able to compress the initram. config INITRAMFS_COMPRESSION_LZO bool "LZO" depends on RD_LZO help - Its compression ratio is the poorest among the choices. The kernel - size is about 10% bigger than gzip; however its speed - (both compression and decompression) is the fastest. + Its compression ratio is the second poorest amongst the choices. The + kernel size is about 10% bigger than gzip. Despite that, its + decompression speed is the second fastest and its compression speed + is quite fast too. + + If you choose this, keep in mind that you may need to install the lzop + tool to be able to compress the initram. + +config INITRAMFS_COMPRESSION_LZ4 + bool "LZ4" + depends on RD_LZ4 + help + It's compression ratio is the poorest amongst the choices. The kernel + size is about 15% bigger than gzip; however its decompression speed + is the fastest. + + If you choose this, keep in mind that most distros don't provide lz4 + by default which could cause a build failure. + +config INITRAMFS_COMPRESSION_ZSTD + bool "ZSTD" + depends on RD_ZSTD + help + ZSTD is a compression algorithm targeting intermediate compression + with fast decompression speed. It will compress better than GZIP and + decompress around the same speed as LZO, but slower than LZ4. + + If you choose this, keep in mind that you may need to install the zstd + tool to be able to compress the initram. + +config INITRAMFS_COMPRESSION_NONE + bool "None" + help + Do not compress the built-in initramfs at all. This may sound wasteful + in space, but, you should be aware that the built-in initramfs will be + compressed at a later stage anyways along with the rest of the kernel, + on those architectures that support this. However, not compressing the + initramfs may lead to slightly higher memory consumption during a + short time at boot, while both the cpio image and the unpacked + filesystem image will be present in memory simultaneously endchoice |