Commit 30314804 authored by Lasse Collin's avatar Lasse Collin Committed by Linus Torvalds
Browse files

x86: support XZ-compressed kernel 



This integrates the XZ decompression code to the x86 pre-boot code.

mkpiggy.c is updated to reserve about 32 KiB more buffer safety margin for
kernel decompression.  It is done unconditionally for all decompressors to
keep the code simpler.

The XZ decompressor needs around 30 KiB of heap, so the heap size is
increased to 32 KiB on both x86-32 and x86-64.

Documentation/x86/boot.txt is updated to list the XZ magic number.

With the x86 BCJ filter in XZ, XZ-compressed x86 kernel tends to be a few
percent smaller than the equivalent LZMA-compressed kernel.

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 3ebe1243

Documentation/x86/boot.txt

+3 −3
Original line number Diff line number Diff line
@@ -622,9 +622,9 @@ Protocol: 2.08+ 
  The payload may be compressed. The format of both the compressed and

  uncompressed data should be determined using the standard magic

  numbers.  The currently supported compression formats are gzip

  (magic numbers 1F 8B or 1F 9E), bzip2 (magic number 42 5A) and LZMA

  (magic number 5D 00).  The uncompressed payload is currently always ELF

  (magic number 7F 45 4C 46).

  (magic numbers 1F 8B or 1F 9E), bzip2 (magic number 42 5A), LZMA

  (magic number 5D 00), and XZ (magic number FD 37).  The uncompressed

  payload is currently always ELF (magic number 7F 45 4C 46).

  

Field name:	payload_length

Type:		read

arch/x86/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -51,6 +51,7 @@ config X86 
	select HAVE_KERNEL_GZIP

	select HAVE_KERNEL_BZIP2

	select HAVE_KERNEL_LZMA

	select HAVE_KERNEL_XZ

	select HAVE_KERNEL_LZO

	select HAVE_HW_BREAKPOINT

	select HAVE_MIXED_BREAKPOINTS_REGS

arch/x86/boot/compressed/Makefile

+4 −1
Original line number Diff line number Diff line
@@ -4,7 +4,7 @@ 
# create a compressed vmlinux image from the original vmlinux

#



targets := vmlinux.lds vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma vmlinux.bin.lzo head_$(BITS).o misc.o string.o cmdline.o early_serial_console.o piggy.o

targets := vmlinux.lds vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma vmlinux.bin.xz vmlinux.bin.lzo head_$(BITS).o misc.o string.o cmdline.o early_serial_console.o piggy.o



KBUILD_CFLAGS := -m$(BITS) -D__KERNEL__ $(LINUX_INCLUDE) -O2

KBUILD_CFLAGS += -fno-strict-aliasing -fPIC
@@ -49,12 +49,15 @@ $(obj)/vmlinux.bin.bz2: $(vmlinux.bin.all-y) FORCE 
	$(call if_changed,bzip2)

$(obj)/vmlinux.bin.lzma: $(vmlinux.bin.all-y) FORCE

	$(call if_changed,lzma)

$(obj)/vmlinux.bin.xz: $(vmlinux.bin.all-y) FORCE

	$(call if_changed,xzkern)

$(obj)/vmlinux.bin.lzo: $(vmlinux.bin.all-y) FORCE

	$(call if_changed,lzo)



suffix-$(CONFIG_KERNEL_GZIP)	:= gz

suffix-$(CONFIG_KERNEL_BZIP2)	:= bz2

suffix-$(CONFIG_KERNEL_LZMA)	:= lzma

suffix-$(CONFIG_KERNEL_XZ)	:= xz

suffix-$(CONFIG_KERNEL_LZO) 	:= lzo



quiet_cmd_mkpiggy = MKPIGGY $@

arch/x86/boot/compressed/misc.c

+4 −0
Original line number Diff line number Diff line
@@ -139,6 +139,10 @@ static int lines, cols; 
#include "../../../../lib/decompress_unlzma.c"

#endif



#ifdef CONFIG_KERNEL_XZ

#include "../../../../lib/decompress_unxz.c"

#endif



#ifdef CONFIG_KERNEL_LZO

#include "../../../../lib/decompress_unlzo.c"

#endif

arch/x86/boot/compressed/mkpiggy.c

+1 −1
Original line number Diff line number Diff line
@@ -74,7 +74,7 @@ int main(int argc, char *argv[]) 


	offs = (olen > ilen) ? olen - ilen : 0;

	offs += olen >> 12;	/* Add 8 bytes for each 32K block */

	offs += 32*1024 + 18;	/* Add 32K + 18 bytes slack */

	offs += 64*1024 + 128;	/* Add 64K + 128 bytes slack */

	offs = (offs+4095) & ~4095; /* Round to a 4K boundary */



	printf(".section \".rodata..compressed\",\"a\",@progbits\n");

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