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MicroLZMA is a yet another header format variant where the first byte of a raw LZMA stream (without the end of stream marker) has been replaced with a bitwise-negation of the lc/lp/pb properties byte. MicroLZMA was created to be used in EROFS but can be used by other things too where wasting minimal amount of space for headers is important. This is implemented using most of the LZMA2 code as is so the amount of new code is small. The API has a few extra features compared to the XZ decoder. On the other hand, the API lacks XZ_BUF_ERROR support which is important to take into account when using this API. MicroLZMA doesn't support BCJ filters. In theory they could be added later as there are many unused/reserved values for the first byte of the compressed stream but in practice it is somewhat unlikely to happen due to a few implementation reasons. Link: https://lore.kernel.org/r/20211010213145.17462-5-xiang@kernel.org Signed-off-by: Lasse Collin <lasse.collin@tukaani.org> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
72 lines
1.7 KiB
Plaintext
72 lines
1.7 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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config XZ_DEC
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tristate "XZ decompression support"
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select CRC32
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help
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LZMA2 compression algorithm and BCJ filters are supported using
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the .xz file format as the container. For integrity checking,
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CRC32 is supported. See Documentation/staging/xz.rst for more information.
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if XZ_DEC
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config XZ_DEC_X86
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bool "x86 BCJ filter decoder" if EXPERT
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default y
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select XZ_DEC_BCJ
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config XZ_DEC_POWERPC
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bool "PowerPC BCJ filter decoder" if EXPERT
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default y
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select XZ_DEC_BCJ
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config XZ_DEC_IA64
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bool "IA-64 BCJ filter decoder" if EXPERT
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default y
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select XZ_DEC_BCJ
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config XZ_DEC_ARM
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bool "ARM BCJ filter decoder" if EXPERT
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default y
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select XZ_DEC_BCJ
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config XZ_DEC_ARMTHUMB
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bool "ARM-Thumb BCJ filter decoder" if EXPERT
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default y
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select XZ_DEC_BCJ
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config XZ_DEC_SPARC
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bool "SPARC BCJ filter decoder" if EXPERT
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default y
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select XZ_DEC_BCJ
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config XZ_DEC_MICROLZMA
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bool "MicroLZMA decoder"
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default n
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help
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MicroLZMA is a header format variant where the first byte
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of a raw LZMA stream (without the end of stream marker) has
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been replaced with a bitwise-negation of the lc/lp/pb
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properties byte. MicroLZMA was created to be used in EROFS
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but can be used by other things too where wasting minimal
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amount of space for headers is important.
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Unless you know that you need this, say N.
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endif
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config XZ_DEC_BCJ
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bool
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default n
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config XZ_DEC_TEST
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tristate "XZ decompressor tester"
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default n
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depends on XZ_DEC
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help
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This allows passing .xz files to the in-kernel XZ decoder via
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a character special file. It calculates CRC32 of the decompressed
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data and writes diagnostics to the system log.
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Unless you are developing the XZ decoder, you don't need this
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and should say N.
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