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diff --git a/usr/Kconfig b/usr/Kconfig new file mode 100644 index 0000000000..8bbcf699fe --- /dev/null +++ b/usr/Kconfig @@ -0,0 +1,229 @@ +# SPDX-License-Identifier: GPL-2.0 +# +# Configuration for initramfs +# + +config INITRAMFS_SOURCE + string "Initramfs source file(s)" + default "" + help + This can be either a single cpio archive with a .cpio suffix or a + space-separated list of directories and files for building the + initramfs image. A cpio archive should contain a filesystem archive + to be used as an initramfs image. Directories should contain a + filesystem layout to be included in the initramfs image. Files + should contain entries according to the format described by the + "usr/gen_init_cpio" program in the kernel tree. + + When multiple directories and files are specified then the + initramfs image will be the aggregate of all of them. + + 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 + 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". + +config INITRAMFS_ROOT_GID + int "Group ID to map to 0 (group root)" + depends on INITRAMFS_SOURCE!="" + default "0" + help + 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 ramdisk/ramfs compressed using gzip" + default y + 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 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 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 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 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 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" + depends on INITRAMFS_SOURCE != "" + help + 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. 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. + + Keep in mind that your build system needs to provide the appropriate + compression tool to compress the generated initram cpio file for + embedding. + + If in doubt, select 'None' + +config INITRAMFS_COMPRESSION_GZIP + bool "Gzip" + depends on RD_GZIP + help + 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 + 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 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 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 + It's compression ratio is the second poorest amongst the choices. The + kernel size is about 10% bigger than gzip. Despite that, it's + decompression speed is the second fastest and it's 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 |