diff options
| author | Lasse Collin <lasse.collin@tukaani.org> | 2011-01-12 17:01:23 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-01-13 08:03:25 -0800 |
| commit | 3ebe12439ba7fc62e1d6ecb569b7287771716ca1 (patch) | |
| tree | 65945a63ad1474489d80c8ca1fb1c1c8091fb7a2 /init | |
| parent | 24fa0402a9b6a537e87e38341e78b7da86486846 (diff) | |
decompressors: add boot-time XZ support
This implements the API defined in <linux/decompress/generic.h> which is
used for kernel, initramfs, and initrd decompression. This patch together
with the first patch is enough for XZ-compressed initramfs and initrd;
XZ-compressed kernel will need arch-specific changes.
The buffering requirements described in decompress_unxz.c are stricter
than with gzip, so the relevant changes should be done to the
arch-specific code when adding support for XZ-compressed kernel.
Similarly, the heap size in arch-specific pre-boot code may need to be
increased (30 KiB is enough).
The XZ decompressor needs memmove(), memeq() (memcmp() == 0), and
memzero() (memset(ptr, 0, size)), which aren't available in all
arch-specific pre-boot environments. I'm including simple versions in
decompress_unxz.c, but a cleaner solution would naturally be nicer.
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>
Diffstat (limited to 'init')
| -rw-r--r-- | init/Kconfig | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/init/Kconfig b/init/Kconfig index 8dfd094e687..ea176e8edbd 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -130,13 +130,16 @@ config HAVE_KERNEL_BZIP2 config HAVE_KERNEL_LZMA bool +config HAVE_KERNEL_XZ + bool + config HAVE_KERNEL_LZO bool choice prompt "Kernel compression mode" default KERNEL_GZIP - depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO + depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO help The linux kernel is a kind of self-extracting executable. Several compression algorithms are available, which differ @@ -181,6 +184,21 @@ config KERNEL_LZMA two. Compression is slowest. The kernel size is about 33% smaller with LZMA in comparison to gzip. +config KERNEL_XZ + bool "XZ" + depends on HAVE_KERNEL_XZ + help + XZ uses the LZMA2 algorithm and instruction set specific + 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. + + The speed is about the same as with LZMA: The decompression + speed of XZ is better than that of bzip2 but worse than gzip + and LZO. Compression is slow. + config KERNEL_LZO bool "LZO" depends on HAVE_KERNEL_LZO |