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| -rw-r--r-- | usr/Kconfig | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/usr/Kconfig b/usr/Kconfig index bf8e8f15358f..6278f135256d 100644 --- a/usr/Kconfig +++ b/usr/Kconfig @@ -99,8 +99,125 @@ config RD_LZ4 Support loading of a LZ4 encoded initial ramdisk or cpio buffer If unsure, say N. +choice + prompt "Built-in initramfs compression mode" + depends on INITRAMFS_SOURCE!="" + optional + 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_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 + +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. + +endchoice + config INITRAMFS_COMPRESSION string + default "" if INITRAMFS_COMPRESSION_NONE + default ".gz" if INITRAMFS_COMPRESSION_GZIP + default ".bz2" if INITRAMFS_COMPRESSION_BZIP2 + default ".lzma" if INITRAMFS_COMPRESSION_LZMA + default ".xz" if INITRAMFS_COMPRESSION_XZ + default ".lzo" if INITRAMFS_COMPRESSION_LZO + default ".lz4" if INITRAMFS_COMPRESSION_LZ4 default ".gz" if RD_GZIP default ".lz4" if RD_LZ4 default ".lzo" if RD_LZO |