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* xz: adjust arch-specific options for better kernel compressionLasse Collin2024-09-011-5/+137
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Use LZMA2 options that match the arch-specific alignment of instructions. This change reduces compressed kernel size 0-2 % depending on the arch. On 1-byte-aligned x86 it makes no difference and on 4-byte-aligned archs it helps the most. Use the ARM-Thumb filter for ARM-Thumb2 kernels. This reduces compressed kernel size about 5 %.[1] Previously such kernels were compressed using the ARM filter which didn't do anything useful with ARM-Thumb2 code. Add BCJ filter support for ARM64 and RISC-V. Compared to unfiltered XZ or plain LZMA, the compressed kernel size is reduced about 5 % on ARM64 and 7 % on RISC-V. A new enough version of the xz tool is required: 5.4.0 for ARM64 and 5.6.0 for RISC-V. With an old xz version, a message is printed to standard error and the kernel is compressed without the filter. Update lib/decompress_unxz.c to match the changes to xz_wrap.sh. Update the CONFIG_KERNEL_XZ help text in init/Kconfig: - Add the RISC-V and ARM64 filters. - Clarify that the PowerPC filter is for big endian only. - Omit IA-64. Link: https://lore.kernel.org/lkml/1637379771-39449-1-git-send-email-zhongjubin@huawei.com/ [1] Link: https://lkml.kernel.org/r/20240721133633.47721-15-lasse.collin@tukaani.org Signed-off-by: Lasse Collin <lasse.collin@tukaani.org> Reviewed-by: Sam James <sam@gentoo.org> Cc: Simon Glass <sjg@chromium.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Jubin Zhong <zhongjubin@huawei.com> Cc: Jules Maselbas <jmaselbas@zdiv.net> Cc: Emil Renner Berthing <emil.renner.berthing@canonical.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Joel Stanley <joel@jms.id.au> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Krzysztof Kozlowski <krzk@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rui Li <me@lirui.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
* xz: use 128 MiB dictionary and force single-threaded modeLasse Collin2024-09-011-1/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This only affects kernel image compression, not any other xz usage. Desktop kernels on x86-64 are already around 60 MiB. Using a dictionary larger than 32 MiB should have no downsides nowadays as anyone building the kernel should have plenty of RAM. 128 MiB dictionary needs 1346 MiB of RAM with xz versions 5.0.x - 5.6.x in single-threaded mode. On archs that use xz_wrap.sh, kernel decompression is done in single-call mode so a larger dictionary doesn't affect boot-time memory requirements. xz >= 5.6.0 uses multithreaded mode by default which compresses slightly worse than single-threaded mode. Kernel compression rarely used more than one thread anyway because with 32 MiB dictionary size the default block size was 96 MiB in multithreaded mode. So only a single thread was used anyway unless the kernel was over 96 MiB. Comparison to CONFIG_KERNEL_LZMA: It uses "lzma -9" which mapped to 32 MiB dictionary in LZMA Utils 4.32.7 (the final release in 2008). Nowadays the lzma tool on most systems is from XZ Utils where -9 maps to 64 MiB dictionary. So using a 32 MiB dictionary with CONFIG_KERNEL_XZ may have compressed big kernels slightly worse than the old LZMA option. Comparison to CONFIG_KERNEL_ZSTD: zstd uses 128 MiB dictionary. Link: https://lkml.kernel.org/r/20240721133633.47721-14-lasse.collin@tukaani.org Signed-off-by: Lasse Collin <lasse.collin@tukaani.org> Reviewed-by: Sam James <sam@gentoo.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Emil Renner Berthing <emil.renner.berthing@canonical.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Joel Stanley <joel@jms.id.au> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Jubin Zhong <zhongjubin@huawei.com> Cc: Jules Maselbas <jmaselbas@zdiv.net> Cc: Krzysztof Kozlowski <krzk@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rui Li <me@lirui.org> Cc: Simon Glass <sjg@chromium.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
* xz: switch from public domain to BSD Zero Clause License (0BSD)Lasse Collin2024-09-011-4/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Remove the public domain notices and add SPDX license identifiers. Change MODULE_LICENSE from "GPL" to "Dual BSD/GPL" because 0BSD should count as a BSD license variant here. The switch to 0BSD was done in the upstream XZ Embedded project because public domain has (real or perceived) legal issues in some jurisdictions. Link: https://lkml.kernel.org/r/20240721133633.47721-4-lasse.collin@tukaani.org Signed-off-by: Lasse Collin <lasse.collin@tukaani.org> Reviewed-by: Sam James <sam@gentoo.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Emil Renner Berthing <emil.renner.berthing@canonical.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Joel Stanley <joel@jms.id.au> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Jubin Zhong <zhongjubin@huawei.com> Cc: Jules Maselbas <jmaselbas@zdiv.net> Cc: Krzysztof Kozlowski <krzk@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rui Li <me@lirui.org> Cc: Simon Glass <sjg@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
* scripts: clean up IA-64 codeMasahiro Yamada2023-12-031-1/+0
| | | | | | | | A little more janitorial work after commit cf8e8658100d ("arch: Remove Itanium (IA-64) architecture"). Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
* kbuild: add variables for compression toolsDenis Efremov2020-06-061-1/+1
| | | | | | | | | | | | | | | | | | | | Allow user to use alternative implementations of compression tools, such as pigz, pbzip2, pxz. For example, multi-threaded tools to speed up the build: $ make GZIP=pigz BZIP2=pbzip2 Variables _GZIP, _BZIP2, _LZOP are used internally because original env vars are reserved by the tools. The use of GZIP in gzip tool is obsolete since 2015. However, alternative implementations (e.g., pigz) still rely on it. BZIP2, BZIP, LZOP vars are not obsolescent. The credit goes to @grsecurity. As a sidenote, for multi-threaded lzma, xz compression one can use: $ export XZ_OPT="--threads=0" Signed-off-by: Denis Efremov <efremov@linux.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
* kbuild: Make scripts executableMichal Marek2014-08-201-0/+0
| | | | | | | The Makefiles call the respective interpreter explicitly, but this makes it easier to use the scripts manually. Signed-off-by: Michal Marek <mmarek@suse.cz>
* xz: Enable BCJ filters on SPARC and 32-bit x86Lasse Collin2012-04-181-2/+2
| | | | | | | | | | | | | | | | The BCJ filters were meant to be enabled already on these archs, but the xz_wrap.sh script was buggy. Enabling the filters should give smaller kernel images. xz_wrap.sh will now use $SRCARCH instead of $ARCH to detect the architecture. That way it doesn't need to care about the subarchs (like i386 vs. x86_64) since the BCJ filters don't care either. Signed-off-by: Lasse Collin <lasse.collin@tukaani.org> Acked-by: Jan Beulich <jbeulich@suse.com> Acked-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* decompressors: add XZ decompressor moduleLasse Collin2011-01-131-0/+23
In userspace, the .lzma format has become mostly a legacy file format that got superseded by the .xz format. Similarly, LZMA Utils was superseded by XZ Utils. These patches add support for XZ decompression into the kernel. Most of the code is as is from XZ Embedded <http://tukaani.org/xz/embedded.html>. It was written for the Linux kernel but is usable in other projects too. Advantages of XZ over the current LZMA code in the kernel: - Nice API that can be used by other kernel modules; it's not limited to kernel, initramfs, and initrd decompression. - Integrity check support (CRC32) - BCJ filters improve compression of executable code on certain architectures. These together with LZMA2 can produce a few percent smaller kernel or Squashfs images than plain LZMA without making the decompression slower. This patch: Add the main decompression code (xz_dec), testing module (xz_dec_test), wrapper script (xz_wrap.sh) for the xz command line tool, and documentation. The xz_dec module is enough to have a usable XZ decompressor e.g. for Squashfs. Signed-off-by: Lasse Collin <lasse.collin@tukaani.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Alain Knaff <alain@knaff.lu> Cc: Albin Tonnerre <albin.tonnerre@free-electrons.com> Cc: Phillip Lougher <phillip@lougher.demon.co.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>