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Commit 3ebe1243 authored by Lasse Collin's avatar Lasse Collin Committed by Linus Torvalds
Browse files

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: default avatarLasse 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 24fa0402

include/linux/decompress/unxz.h

0 → 100644
+19 −0
Original line number Diff line number Diff line 
/*

 * Wrapper for decompressing XZ-compressed kernel, initramfs, and initrd

 *

 * Author: Lasse Collin <lasse.collin@tukaani.org>

 *

 * This file has been put into the public domain.

 * You can do whatever you want with this file.

 */



#ifndef DECOMPRESS_UNXZ_H

#define DECOMPRESS_UNXZ_H



int unxz(unsigned char *in, int in_size,

	 int (*fill)(void *dest, unsigned int size),

	 int (*flush)(void *src, unsigned int size),

	 unsigned char *out, int *in_used,

	 void (*error)(char *x));



#endif

init/Kconfig

+19 −1
Original line number Diff line number Diff line
@@ -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

lib/Kconfig

+4 −0
Original line number Diff line number Diff line
@@ -122,6 +122,10 @@ config DECOMPRESS_BZIP2 
config DECOMPRESS_LZMA

	tristate



config DECOMPRESS_XZ

	select XZ_DEC

	tristate



config DECOMPRESS_LZO

	select LZO_DECOMPRESS

	tristate

lib/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -75,6 +75,7 @@ obj-$(CONFIG_RAID6_PQ) += raid6/ 
lib-$(CONFIG_DECOMPRESS_GZIP) += decompress_inflate.o

lib-$(CONFIG_DECOMPRESS_BZIP2) += decompress_bunzip2.o

lib-$(CONFIG_DECOMPRESS_LZMA) += decompress_unlzma.o

lib-$(CONFIG_DECOMPRESS_XZ) += decompress_unxz.o

lib-$(CONFIG_DECOMPRESS_LZO) += decompress_unlzo.o



obj-$(CONFIG_TEXTSEARCH) += textsearch.o

lib/decompress.c

+5 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 


#include <linux/decompress/bunzip2.h>

#include <linux/decompress/unlzma.h>

#include <linux/decompress/unxz.h>

#include <linux/decompress/inflate.h>

#include <linux/decompress/unlzo.h>
@@ -23,6 +24,9 @@ 
#ifndef CONFIG_DECOMPRESS_LZMA

# define unlzma NULL

#endif

#ifndef CONFIG_DECOMPRESS_XZ

# define unxz NULL

#endif

#ifndef CONFIG_DECOMPRESS_LZO

# define unlzo NULL

#endif
@@ -36,6 +40,7 @@ static const struct compress_format { 
	{ {037, 0236}, "gzip", gunzip },

	{ {0x42, 0x5a}, "bzip2", bunzip2 },

	{ {0x5d, 0x00}, "lzma", unlzma },

	{ {0xfd, 0x37}, "xz", unxz },

	{ {0x89, 0x4c}, "lzo", unlzo },

	{ {0, 0}, NULL, NULL }

};