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    Subject[PATCH 2/2] lzma support: lzma compressed kernel image
    This patch is against 2.6.12-rc6.

    Makes it possible on i386 to select lzma compression instead of gzip
    compression, this is especially usefull for embedded systems or when
    there are special size restrictions, like a kernel on a floppy image.

    Other architectures aren't affected, obviously.

    I also want to mention that the misc_lzma.c is much cleaner than the
    orginal misc.c :-)

    The memory requirements are only a little big higher than with gzip,
    namely low_buffer_size or even lower when !high_loaded.

    Size example:
    -rw-r--r-- 1 ijuz ijuz 1233099 Jun 7 20:12 bzImage.gz
    -rw-r--r-- 1 ijuz ijuz 1041267 Jun 7 20:12 bzImage.lzma
    (download them from here to try them out:
    http://debian.christian-leber.de/kernel_lzma/)

    To build a kernel with lzma compression you have to go to:
    Executable file formats -> Kernel compression format


    Building the lzma tool cut and paste style:

    mkdir build-lzma
    wget http://www.7-zip.org/dl/lzma417.tar.bz2
    tar xjf lzma417.tar.bz2
    cd SRC/7zip/Compress/LZMA_Alone/
    make
    cp lzma ../../../../../
    cd ../../../../../


    Signed-off-by: Christian Leber <christian@leber.de>


    --- linux-2.6.12-rc6.orig/arch/i386/Kconfig 2005-06-06 17:22:29.000000000 +0200
    +++ linux-2.6.12-rc6/arch/i386/Kconfig 2005-06-07 21:33:40.000000000 +0200
    @@ -1236,6 +1236,34 @@

    source "fs/Kconfig.binfmt"

    +choice
    + prompt "Kernel compression format"
    + depends on EXPERIMENTAL
    + default KERNEL_GZIP
    +
    +config KERNEL_GZIP
    + bool "Compress kernel image using gzip"
    + help
    + The linux kernel is a self-extracting executable.
    +
    + Choosing Gzip here, makes the kernel image beeing compressed
    + using Gzip.
    +
    + Gzip is the standard compression method for the kernel image.
    + If you do not know what to say, take gzip.
    +
    +
    +config KERNEL_LZMA
    + bool "Compress kernel image using lzma (EXPERIMENTAL)"
    + depends on EXPERIMENTAL
    + help
    + The linux kernel is a self-extracting executable.
    +
    + Choosing lzma here, makes the kernel beeing compressed using
    + lzma.
    +
    +endchoice
    +
    endmenu

    source "drivers/Kconfig"
    --- linux-2.6.12-rc6.orig/arch/i386/boot/compressed/misc_lzma.c 1970-01-01 01:00:00.000000000 +0100
    +++ linux-2.6.12-rc6/arch/i386/boot/compressed/misc_lzma.c 2005-06-07 21:39:17.000000000 +0200
    @@ -0,0 +1,296 @@
    +/*
    + * misc.c
    + *
    + * This code uses LzmaDecode.c and LzmaDecode.h to decompress the lzma
    + * compressed Linux kernel
    + *
    + * malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994
    + * puts by Nick Holloway 1993, better puts by Martin Mares 1995
    + * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
    + * lzma decompression support by Christian Leber, June 2005
    + */
    +
    +#include <linux/linkage.h>
    +#include <linux/vmalloc.h>
    +#include <linux/tty.h>
    +#include <video/edid.h>
    +#include <asm/io.h>
    +
    +#undef memcpy
    +/*
    + * Why do we do this? Don't ask me..
    + *
    + * Incomprehensible are the ways of bootloaders.
    + */
    +
    +static void* memcpy(void *, __const void *, size_t);
    +static void error(char *m);
    +
    +/*
    + * This is set up by the setup-routine at boot-time
    + */
    +static unsigned char *real_mode; /* Pointer to real-mode data */
    +
    +#define RM_EXT_MEM_K (*(unsigned short *)(real_mode + 0x2))
    +#ifndef STANDARD_MEMORY_BIOS_CALL
    +#define RM_ALT_MEM_K (*(unsigned long *)(real_mode + 0x1e0))
    +#endif
    +#define RM_SCREEN_INFO (*(struct screen_info *)(real_mode+0))
    +
    +extern char input_data[];
    +extern int input_len;
    +
    +static long bytes_out = 0;
    +
    +/* with high_loaded it points to high_buffer_start otherwise to 1MB */
    +static unsigned char *working_area;
    +
    +static void putstr(const char *);
    +
    +extern int end;
    +static long free_mem_ptr = (long)&end;
    +
    +#define LOW_BUFFER_START 0x2000
    +#define LOW_BUFFER_MAX 0x90000
    +#define HEAP_SIZE 0x3000
    +static unsigned int low_buffer_end, low_buffer_size;
    +static int high_loaded =0;
    +static unsigned char *high_buffer_start /* = (unsigned char *)(((unsigned log)&end) + HEAP_SIZE)*/;
    +
    +static char *vidmem = (char *)0xb8000;
    +static int vidport;
    +static int lines, cols;
    +
    +#ifdef CONFIG_X86_NUMAQ
    +static void * xquad_portio = NULL;
    +#endif
    +
    +static void scroll(void)
    +{
    + int i;
    +
    + memcpy ( vidmem, vidmem + cols * 2, ( lines - 1 ) * cols * 2 );
    + for ( i = ( lines - 1 ) * cols * 2; i < lines * cols * 2; i += 2 )
    + vidmem[i] = ' ';
    +}
    +
    +static void putstr(const char *s)
    +{
    + int x,y,pos;
    + char c;
    +
    + x = RM_SCREEN_INFO.orig_x;
    + y = RM_SCREEN_INFO.orig_y;
    +
    + while ( ( c = *s++ ) != '\0' ) {
    + if ( c == '\n' ) {
    + x = 0;
    + if ( ++y >= lines ) {
    + scroll();
    + y--;
    + }
    + } else {
    + vidmem [ ( x + cols * y ) * 2 ] = c;
    + if ( ++x >= cols ) {
    + x = 0;
    + if ( ++y >= lines ) {
    + scroll();
    + y--;
    + }
    + }
    + }
    + }
    +
    + RM_SCREEN_INFO.orig_x = x;
    + RM_SCREEN_INFO.orig_y = y;
    +
    + pos = (x + cols * y) * 2; /* Update cursor position */
    + outb_p(14, vidport);
    + outb_p(0xff & (pos >> 9), vidport+1);
    + outb_p(15, vidport);
    + outb_p(0xff & (pos >> 1), vidport+1);
    +}
    +
    +static void* memcpy(void* __dest, __const void* __src,
    + size_t __n)
    +{
    + int i;
    + char *d = (char *)__dest, *s = (char *)__src;
    +
    + for (i=0;i<__n;i++) d[i] = s[i];
    + return __dest;
    +}
    +
    +static void error(char *x)
    +{
    + putstr("\n\n");
    + putstr(x);
    + putstr("\n\n -- System halted");
    +
    + while(1); /* Halt */
    +}
    +
    +#define STACK_SIZE (4096)
    +
    +long user_stack [STACK_SIZE];
    +
    +struct {
    + long * a;
    + short b;
    + } stack_start = { & user_stack [STACK_SIZE] , __BOOT_DS };
    +
    +static void setup_normal_output_buffer(void)
    +{
    +#ifdef STANDARD_MEMORY_BIOS_CALL
    + if (RM_EXT_MEM_K < 1024) error("Less than 2MB of memory");
    +#else
    + if ((RM_ALT_MEM_K > RM_EXT_MEM_K ? RM_ALT_MEM_K : RM_EXT_MEM_K) < 1024) error("Less than 2MB of memory");
    +#endif
    + working_area = (char *)0x100000; /* Points to 1M */
    +}
    +
    +struct moveparams {
    + unsigned char *low_buffer_start; int lcount;
    + unsigned char *high_buffer_start; int hcount;
    +};
    +
    +static void setup_output_buffer_if_we_run_high(struct moveparams *mv)
    +{
    + high_buffer_start = (unsigned char *)(((unsigned long)&end) + HEAP_SIZE);
    +#ifdef STANDARD_MEMORY_BIOS_CALL
    + if (RM_EXT_MEM_K < (3*1024)) error("Less than 4MB of memory");
    +#else
    + if ((RM_ALT_MEM_K > RM_EXT_MEM_K ? RM_ALT_MEM_K : RM_EXT_MEM_K) <
    + (3*1024))
    + error("Less than 4MB of memory");
    +#endif
    + mv->low_buffer_start = (char *)LOW_BUFFER_START;
    + low_buffer_end = ((unsigned int)real_mode > LOW_BUFFER_MAX
    + ? LOW_BUFFER_MAX : (unsigned int)real_mode) & ~0xfff;
    + low_buffer_size = low_buffer_end - LOW_BUFFER_START;
    + high_loaded = 1;
    + if ( (0x100000 + low_buffer_size) > ((unsigned long)high_buffer_start)) {
    + high_buffer_start = (unsigned char *)(0x100000 + low_buffer_size);
    + mv->hcount = 0; /* say: we need not to move high_buffer */
    + } else {
    + mv->hcount = -1;
    + }
    + mv->high_buffer_start = high_buffer_start;
    + working_area = high_buffer_start;
    +}
    +
    +static void close_output_buffer_if_we_run_high(struct moveparams *mv)
    +{
    + if (bytes_out > low_buffer_size) {
    + mv->lcount = low_buffer_size;
    + if (mv->hcount)
    + mv->hcount = bytes_out - low_buffer_size;
    + } else {
    + mv->lcount = bytes_out;
    + mv->hcount = 0;
    + }
    +}
    +
    +/* this defines increase the speed significantly */
    +#define _LZMA_PROB32
    +#define _LZMA_LOC_OPT
    +#include "../../../../lib/LzmaDecode.h"
    +#include "../../../../lib/LzmaDecode.c"
    +
    +/*
    + * Do the lzma decompression
    + */
    +static int lzma_unzip(void)
    +{
    + unsigned int i;
    + unsigned char prop0, properties[5];
    + unsigned int lc, lp, pb; /* lzma properties */
    + unsigned char* workspace;
    + unsigned int uncompressed_size, workspace_size;
    + unsigned int memsize;
    +
    + for (i=0;i<=5;i++) {
    + properties[i] = (unsigned char)input_data[i];
    + }
    +
    + uncompressed_size = 0;
    + for (i = 0; i < 4; i++) {
    + uncompressed_size += (unsigned char)input_data[5+i] << (i * 8);
    + }
    +
    + prop0 = properties[0];
    + if (prop0 >= (9*5*5)) {
    + error("Properties error");
    + }
    + for (pb = 0; prop0 >= (9 * 5); pb++, prop0 -= (9 * 5));
    + for (lp = 0; prop0 >= 9; lp++, prop0 -= 9);
    + lc = prop0;
    +
    + workspace_size = (LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp)))* sizeof(CProb);
    + workspace = working_area + uncompressed_size;
    +
    +
    + /* now we have to check if there is enough memory at all */
    +#ifdef STANDARD_MEMORY_BIOS_CALL
    + memsize = RM_EXT_MEM_K * 1024;
    +#else
    + if(RM_ALT_MEM_K > RM_EXT_MEM_K)
    + memsize=RM_ALT_MEM_K * 1024;
    + else
    + memsize=RM_EXT_MEM_K * 1024;
    +#endif
    + if( (unsigned int)(workspace + workspace_size) > memsize)
    + error("you don't have enough memory to boot this kernel\n");
    +
    + if (LzmaDecode(workspace, workspace_size, lc, lp, pb,
    + (unsigned char *)input_data + 13, input_len - 13,
    + (unsigned char *)working_area, uncompressed_size,
    + &i) == LZMA_RESULT_OK)
    + {
    + if ( i != uncompressed_size )
    + error( "kernel corrupted!\n");
    + if(high_loaded) {
    + /* when we are high_loaded we have to copy the kernel around
    + * before we can boot */
    + if ( uncompressed_size > low_buffer_size ) {
    + memcpy((char*)LOW_BUFFER_START, high_buffer_start,
    + low_buffer_size);
    + memcpy(high_buffer_start, high_buffer_start+low_buffer_size,
    + uncompressed_size-low_buffer_size);
    + } else {
    + memcpy((char*)LOW_BUFFER_START, high_buffer_start, uncompressed_size );
    + }
    + }
    + bytes_out = i;
    + return 0;
    + }
    + return 1;
    +}
    +
    +
    +asmlinkage int decompress_kernel(struct moveparams *mv, void *rmode)
    +{
    + real_mode = rmode;
    +
    + if (RM_SCREEN_INFO.orig_video_mode == 7) {
    + vidmem = (char *) 0xb0000;
    + vidport = 0x3b4;
    + } else {
    + vidmem = (char *) 0xb8000;
    + vidport = 0x3d4;
    + }
    +
    + lines = RM_SCREEN_INFO.orig_video_lines;
    + cols = RM_SCREEN_INFO.orig_video_cols;
    +
    + if (free_mem_ptr < 0x100000) setup_normal_output_buffer();
    + else setup_output_buffer_if_we_run_high(mv);
    +
    + putstr("Uncompressing (lzma) Linux... ");
    + if( lzma_unzip() != 0 ) {
    + error("inflate error\n");
    + }
    + putstr("Ok, booting the kernel.\n");
    + if (high_loaded) close_output_buffer_if_we_run_high(mv);
    + return high_loaded;
    +}


    --- linux-2.6.12-rc6.orig/arch/i386/boot/compressed/Makefile 2005-06-06 17:22:29.000000000 +0200
    +++ linux-2.6.12-rc6/arch/i386/boot/compressed/Makefile 2005-06-07 22:49:31.000000000 +0200
    @@ -4,22 +4,41 @@
    # create a compressed vmlinux image from the original vmlinux
    #

    -targets := vmlinux vmlinux.bin vmlinux.bin.gz head.o misc.o piggy.o
    +targets := vmlinux vmlinux.bin head.o piggy.o
    EXTRA_AFLAGS := -traditional

    LDFLAGS_vmlinux := -Ttext $(IMAGE_OFFSET) -e startup_32

    -$(obj)/vmlinux: $(obj)/head.o $(obj)/misc.o $(obj)/piggy.o FORCE
    - $(call if_changed,ld)
    - @:
    +LDFLAGS_piggy.o := -r --format binary --oformat elf32-i386 -T

    $(obj)/vmlinux.bin: vmlinux FORCE
    $(call if_changed,objcopy)

    +ifeq ($(CONFIG_KERNEL_GZIP),y)
    +targets += vmlinux.bin.gz misc.o
    +
    +$(obj)/vmlinux: $(obj)/head.o $(obj)/misc.o $(obj)/piggy.o FORCE
    + $(call if_changed,ld)
    + @:
    +
    $(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
    $(call if_changed,gzip)

    -LDFLAGS_piggy.o := -r --format binary --oformat elf32-i386 -T
    -
    $(obj)/piggy.o: $(obj)/vmlinux.scr $(obj)/vmlinux.bin.gz FORCE
    $(call if_changed,ld)
    +endif
    +
    +ifeq ($(CONFIG_KERNEL_LZMA),y)
    +targets += vmlinux.bin.lzma misc_lzma.o
    +
    +$(obj)/vmlinux: $(obj)/head.o $(obj)/misc_lzma.o $(obj)/piggy.o FORCE
    + $(call if_changed,ld)
    + @:
    +
    +$(obj)/vmlinux.bin.lzma: $(obj)/vmlinux.bin FORCE
    + lzma e $(obj)/vmlinux.bin $(obj)/vmlinux.bin.lzma
    +
    +$(obj)/piggy.o: $(obj)/vmlinux.scr $(obj)/vmlinux.bin.lzma FORCE
    + $(call if_changed,ld)
    +endif
    +
    -
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