diff options
| author | Lasse Collin <lasse.collin@tukaani.org> | 2024-07-21 16:36:29 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-09-01 20:43:27 -0700 |
| commit | 7472ff8adad8655f38b060a602f66e59c93c4793 (patch) | |
| tree | 0655f394501d9b04368223bc6442bfd17a57dd4e /init | |
| parent | 8653c909922743bceb4800e5cc26087208c9e0e6 (diff) | |
xz: adjust arch-specific options for better kernel compression
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>
Diffstat (limited to 'init')
| -rw-r--r-- | init/Kconfig | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/init/Kconfig b/init/Kconfig index 5783a0b87517..583cb07176a9 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -310,8 +310,9 @@ config KERNEL_XZ BCJ filters which can improve compression ratio of executable code. The size of the kernel is about 30% smaller with XZ in comparison to gzip. On architectures for which there is a BCJ - filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ - will create a few percent smaller kernel than plain LZMA. + filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC, + and SPARC), XZ will create a few percent smaller kernel than + plain LZMA. The speed is about the same as with LZMA: The decompression speed of XZ is better than that of bzip2 but worse than gzip |