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2 commits

Author SHA1 Message Date
Lasse Collin
0db7bd8ca0 xz: Enable BCJ filters on SPARC and 32-bit x86
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>
2012-04-18 13:13:18 -07:00
Lasse Collin
24fa0402a9 decompressors: add XZ decompressor module
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got superseded by the .xz format.  Similarly, LZMA Utils was superseded by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>
2011-01-13 08:03:24 -08:00