[PATCHv2 0/3] x86: boot protocol updates.

[PATCHv2 0/3] x86: boot protocol updates.

[Ian Campbell]

Updates since last time:
  - Fixed ELF payload patch to work with non-default
    CONFIG_PHYSICAL_START.
  - Grammar fix from Randy Dunlap.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>

[PATCHv2 1/3] x86: use ELF format in compressed images.

[Ian Campbell]

This allows other boot loaders such as the Xen domain builder the
opportunity to extract the ELF file.

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: virtualization@lists.linux-foundation.org
---
 Documentation/i386/boot.txt       |   18 ++++++++++++
 arch/x86/boot/Makefile            |   14 +++++++++
 arch/x86/boot/compressed/Makefile |    2 +-
 arch/x86/boot/compressed/misc.c   |   56 +++++++++++++++++++++++++++++++++++++
 arch/x86/boot/header.S            |    6 ++++
 5 files changed, 95 insertions(+), 1 deletions(-)

diff --git a/Documentation/i386/boot.txt b/Documentation/i386/boot.txt
index fc49b79..b5f5ba1 100644
--- a/Documentation/i386/boot.txt
+++ b/Documentation/i386/boot.txt
@@ -170,6 +170,8 @@ Offset	Proto	Name		Meaning
 0238/4	2.06+	cmdline_size	Maximum size of the kernel command line
 023C/4	2.07+	hardware_subarch Hardware subarchitecture
 0240/8	2.07+	hardware_subarch_data Subarchitecture-specific data
+0248/4	2.08+	compressed_payload_offset
+024C/4	2.08+	compressed_payload_length
 
 (1) For backwards compatibility, if the setup_sects field contains 0, the
     real value is 4.
@@ -512,6 +514,22 @@ Protocol:	2.07+
 
   A pointer to data that is specific to hardware subarch
 
+Field name:	compressed_payload_offset
+Type:		read
+Offset/size:	0x248/4
+Protocol:	2.08+
+
+  If non-zero then this field contains the offset from the end of the
+  real-mode code to the compressed payload. The compression format
+  should be determined using the standard magic number, currently only
+  gzip is used.
+  
+Field name:	compressed_payload_length
+Type:		read
+Offset/size:	0x24c/4
+Protocol:	2.08+
+
+  The length of the compressed payload.
 
 **** THE KERNEL COMMAND LINE
 
diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index f88458e..9695aff 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -94,6 +94,20 @@ $(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE
 
 SETUP_OBJS = $(addprefix $(obj)/,$(setup-y))
 
+sed-offsets := -e 's/^00*/0/' \
+        -e 's/^\([0-9a-fA-F]*\) . \(input_data\|input_data_end\)$$/\#define \2 0x\1/p'
+
+quiet_cmd_offsets = OFFSETS $@
+      cmd_offsets = $(NM) $< | sed -n $(sed-offsets) > $@
+
+$(obj)/offsets.h: $(obj)/compressed/vmlinux FORCE
+	$(call if_changed,offsets)
+
+targets += offsets.h
+
+AFLAGS_header.o += -I$(obj)
+$(obj)/header.o: $(obj)/offsets.h
+
 LDFLAGS_setup.elf	:= -T
 $(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE
 	$(call if_changed,ld)
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index d2b9f3b..92fdd35 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -22,7 +22,7 @@ $(obj)/vmlinux: $(src)/vmlinux_$(BITS).lds $(obj)/head_$(BITS).o $(obj)/misc.o $
 	$(call if_changed,ld)
 	@:
 
-OBJCOPYFLAGS_vmlinux.bin := -O binary -R .note -R .comment -S
+OBJCOPYFLAGS_vmlinux.bin :=  -R .comment -S
 $(obj)/vmlinux.bin: vmlinux FORCE
 	$(call if_changed,objcopy)
 
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 8182e32..69aec2f 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -15,6 +15,10 @@
  * we just keep it from happening
  */
 #undef CONFIG_PARAVIRT
+#ifdef CONFIG_X86_32
+#define _ASM_DESC_H_ 1
+#endif
+
 #ifdef CONFIG_X86_64
 #define _LINUX_STRING_H_ 1
 #define __LINUX_BITMAP_H 1
@@ -22,6 +26,7 @@
 
 #include <linux/linkage.h>
 #include <linux/screen_info.h>
+#include <linux/elf.h>
 #include <asm/io.h>
 #include <asm/page.h>
 #include <asm/boot.h>
@@ -365,6 +370,56 @@ static void error(char *x)
 		asm("hlt");
 }
 
+static void parse_elf(void *output)
+{
+#ifdef CONFIG_X86_64
+	Elf64_Ehdr ehdr;
+	Elf64_Phdr *phdrs, *phdr;
+#else
+	Elf32_Ehdr ehdr;
+	Elf32_Phdr *phdrs, *phdr;
+#endif
+	void *dest;
+	int i;
+
+	memcpy(&ehdr, output, sizeof(ehdr));
+	if(ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
+	   ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
+	   ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
+	   ehdr.e_ident[EI_MAG3] != ELFMAG3)
+	{
+		error("Kernel is not a valid ELF file");
+		return;
+	}
+
+	putstr("Parsing ELF... ");
+
+	phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
+	if (!phdrs)
+		error("Failed to allocate space for phdrs");
+
+	memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
+
+	for (i=0; i<ehdr.e_phnum; i++) {
+		phdr = &phdrs[i];
+
+		switch (phdr->p_type) {
+		case PT_LOAD:
+#ifdef CONFIG_RELOCATABLE
+			dest = output;
+			dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
+#else
+			dest = (void*)(phdr->p_paddr);
+#endif
+			memcpy(dest,
+			       output + phdr->p_offset,
+			       phdr->p_filesz);
+			break;
+		default: /* Ignore other PT_* */ break;
+		}
+	}
+}
+
 asmlinkage void decompress_kernel(void *rmode, memptr heap,
 				  uch *input_data, unsigned long input_len,
 				  uch *output)
@@ -408,6 +463,7 @@ asmlinkage void decompress_kernel(void *rmode, memptr heap,
 	makecrc();
 	putstr("\nDecompressing Linux... ");
 	gunzip();
+	parse_elf(output);
 	putstr("done.\nBooting the kernel.\n");
 	return;
 }
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 64ad901..8471658 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -22,6 +22,7 @@
 #include <asm/page.h>
 #include <asm/setup.h>
 #include "boot.h"
+#include "offsets.h"
 
 SETUPSECTS	= 4			/* default nr of setup-sectors */
 BOOTSEG		= 0x07C0		/* original address of boot-sector */
@@ -223,6 +224,11 @@ hardware_subarch:	.long 0			# subarchitecture, added with 2.07
 
 hardware_subarch_data:	.quad 0
 
+compressed_payload_offset:
+			.long input_data
+compressed_payload_length:
+			.long input_data_end-input_data
+
 # End of setup header #####################################################
 
 	.section ".inittext", "ax"
-- 
1.5.4

[PATCHv2 2/3] x86: add a crc32 checksum to the kernel image.

[Ian Campbell]

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
---
 Documentation/i386/boot.txt |    7 +++
 arch/x86/boot/tools/build.c |   88 ++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 94 insertions(+), 1 deletions(-)

diff --git a/Documentation/i386/boot.txt b/Documentation/i386/boot.txt
index b5f5ba1..b567fb5 100644
--- a/Documentation/i386/boot.txt
+++ b/Documentation/i386/boot.txt
@@ -531,6 +531,13 @@ Protocol:	2.08+
 
   The length of the compressed payload.
 
+**** THE IMAGE CHECKSUM
+
+The CRC-32 is calculated over the entire file using an initial
+remainder of 0xffffffff.  The checksum is appended to the file;
+therefore the CRC of the file up to the limit specified in the syssize
+field of the header is always 0.
+
 **** THE KERNEL COMMAND LINE
 
 The kernel command line has become an important way for the boot
diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c
index b424874..2ba22e8 100644
--- a/arch/x86/boot/tools/build.c
+++ b/arch/x86/boot/tools/build.c
@@ -50,6 +50,75 @@ typedef unsigned long  u32;
 u8 buf[SETUP_SECT_MAX*512];
 int is_big_kernel;
 
+/*----------------------------------------------------------------------*/
+
+static const unsigned int crctab32[] = {
+	0x00000000U, 0x77073096U, 0xee0e612cU, 0x990951baU, 0x076dc419U,
+	0x706af48fU, 0xe963a535U, 0x9e6495a3U, 0x0edb8832U, 0x79dcb8a4U,
+	0xe0d5e91eU, 0x97d2d988U, 0x09b64c2bU, 0x7eb17cbdU, 0xe7b82d07U,
+	0x90bf1d91U, 0x1db71064U, 0x6ab020f2U, 0xf3b97148U, 0x84be41deU,
+	0x1adad47dU, 0x6ddde4ebU, 0xf4d4b551U, 0x83d385c7U, 0x136c9856U,
+	0x646ba8c0U, 0xfd62f97aU, 0x8a65c9ecU, 0x14015c4fU, 0x63066cd9U,
+	0xfa0f3d63U, 0x8d080df5U, 0x3b6e20c8U, 0x4c69105eU, 0xd56041e4U,
+	0xa2677172U, 0x3c03e4d1U, 0x4b04d447U, 0xd20d85fdU, 0xa50ab56bU,
+	0x35b5a8faU, 0x42b2986cU, 0xdbbbc9d6U, 0xacbcf940U, 0x32d86ce3U,
+	0x45df5c75U, 0xdcd60dcfU, 0xabd13d59U, 0x26d930acU, 0x51de003aU,
+	0xc8d75180U, 0xbfd06116U, 0x21b4f4b5U, 0x56b3c423U, 0xcfba9599U,
+	0xb8bda50fU, 0x2802b89eU, 0x5f058808U, 0xc60cd9b2U, 0xb10be924U,
+	0x2f6f7c87U, 0x58684c11U, 0xc1611dabU, 0xb6662d3dU, 0x76dc4190U,
+	0x01db7106U, 0x98d220bcU, 0xefd5102aU, 0x71b18589U, 0x06b6b51fU,
+	0x9fbfe4a5U, 0xe8b8d433U, 0x7807c9a2U, 0x0f00f934U, 0x9609a88eU,
+	0xe10e9818U, 0x7f6a0dbbU, 0x086d3d2dU, 0x91646c97U, 0xe6635c01U,
+	0x6b6b51f4U, 0x1c6c6162U, 0x856530d8U, 0xf262004eU, 0x6c0695edU,
+	0x1b01a57bU, 0x8208f4c1U, 0xf50fc457U, 0x65b0d9c6U, 0x12b7e950U,
+	0x8bbeb8eaU, 0xfcb9887cU, 0x62dd1ddfU, 0x15da2d49U, 0x8cd37cf3U,
+	0xfbd44c65U, 0x4db26158U, 0x3ab551ceU, 0xa3bc0074U, 0xd4bb30e2U,
+	0x4adfa541U, 0x3dd895d7U, 0xa4d1c46dU, 0xd3d6f4fbU, 0x4369e96aU,
+	0x346ed9fcU, 0xad678846U, 0xda60b8d0U, 0x44042d73U, 0x33031de5U,
+	0xaa0a4c5fU, 0xdd0d7cc9U, 0x5005713cU, 0x270241aaU, 0xbe0b1010U,
+	0xc90c2086U, 0x5768b525U, 0x206f85b3U, 0xb966d409U, 0xce61e49fU,
+	0x5edef90eU, 0x29d9c998U, 0xb0d09822U, 0xc7d7a8b4U, 0x59b33d17U,
+	0x2eb40d81U, 0xb7bd5c3bU, 0xc0ba6cadU, 0xedb88320U, 0x9abfb3b6U,
+	0x03b6e20cU, 0x74b1d29aU, 0xead54739U, 0x9dd277afU, 0x04db2615U,
+	0x73dc1683U, 0xe3630b12U, 0x94643b84U, 0x0d6d6a3eU, 0x7a6a5aa8U,
+	0xe40ecf0bU, 0x9309ff9dU, 0x0a00ae27U, 0x7d079eb1U, 0xf00f9344U,
+	0x8708a3d2U, 0x1e01f268U, 0x6906c2feU, 0xf762575dU, 0x806567cbU,
+	0x196c3671U, 0x6e6b06e7U, 0xfed41b76U, 0x89d32be0U, 0x10da7a5aU,
+	0x67dd4accU, 0xf9b9df6fU, 0x8ebeeff9U, 0x17b7be43U, 0x60b08ed5U,
+	0xd6d6a3e8U, 0xa1d1937eU, 0x38d8c2c4U, 0x4fdff252U, 0xd1bb67f1U,
+	0xa6bc5767U, 0x3fb506ddU, 0x48b2364bU, 0xd80d2bdaU, 0xaf0a1b4cU,
+	0x36034af6U, 0x41047a60U, 0xdf60efc3U, 0xa867df55U, 0x316e8eefU,
+	0x4669be79U, 0xcb61b38cU, 0xbc66831aU, 0x256fd2a0U, 0x5268e236U,
+	0xcc0c7795U, 0xbb0b4703U, 0x220216b9U, 0x5505262fU, 0xc5ba3bbeU,
+	0xb2bd0b28U, 0x2bb45a92U, 0x5cb36a04U, 0xc2d7ffa7U, 0xb5d0cf31U,
+	0x2cd99e8bU, 0x5bdeae1dU, 0x9b64c2b0U, 0xec63f226U, 0x756aa39cU,
+	0x026d930aU, 0x9c0906a9U, 0xeb0e363fU, 0x72076785U, 0x05005713U,
+	0x95bf4a82U, 0xe2b87a14U, 0x7bb12baeU, 0x0cb61b38U, 0x92d28e9bU,
+	0xe5d5be0dU, 0x7cdcefb7U, 0x0bdbdf21U, 0x86d3d2d4U, 0xf1d4e242U,
+	0x68ddb3f8U, 0x1fda836eU, 0x81be16cdU, 0xf6b9265bU, 0x6fb077e1U,
+	0x18b74777U, 0x88085ae6U, 0xff0f6a70U, 0x66063bcaU, 0x11010b5cU,
+	0x8f659effU, 0xf862ae69U, 0x616bffd3U, 0x166ccf45U, 0xa00ae278U,
+	0xd70dd2eeU, 0x4e048354U, 0x3903b3c2U, 0xa7672661U, 0xd06016f7U,
+	0x4969474dU, 0x3e6e77dbU, 0xaed16a4aU, 0xd9d65adcU, 0x40df0b66U,
+	0x37d83bf0U, 0xa9bcae53U, 0xdebb9ec5U, 0x47b2cf7fU, 0x30b5ffe9U,
+	0xbdbdf21cU, 0xcabac28aU, 0x53b39330U, 0x24b4a3a6U, 0xbad03605U,
+	0xcdd70693U, 0x54de5729U, 0x23d967bfU, 0xb3667a2eU, 0xc4614ab8U,
+	0x5d681b02U, 0x2a6f2b94U, 0xb40bbe37U, 0xc30c8ea1U, 0x5a05df1bU,
+	0x2d02ef8dU
+};
+
+static u32 partial_crc32_one(u8 c, u32 crc)
+{
+	return crctab32[(crc ^ c) & 0xff] ^ (crc >> 8);
+}
+
+static u32 partial_crc32(const u8 *s, int len, u32 crc)
+{
+	while (len--)
+		crc = partial_crc32_one(*s++, crc);
+	return crc;
+}
+
 static void die(const char * str, ...)
 {
 	va_list args;
@@ -74,6 +143,7 @@ int main(int argc, char ** argv)
 	FILE *file;
 	int fd;
 	void *kernel;
+	u32 crc = 0xffffffffUL;
 
 	if (argc > 2 && !strcmp(argv[1], "-b"))
 	  {
@@ -144,7 +214,8 @@ int main(int argc, char ** argv)
 	kernel = mmap(NULL, sz, PROT_READ, MAP_SHARED, fd, 0);
 	if (kernel == MAP_FAILED)
 		die("Unable to mmap '%s': %m", argv[2]);
-	sys_size = (sz + 15) / 16;
+	/* Number of 16-byte paragraphs, including space for a 4-byte CRC */
+	sys_size = (sz + 15 + 4) / 16;
 	if (!is_big_kernel && sys_size > DEF_SYSSIZE)
 		die("System is too big. Try using bzImage or modules.");
 
@@ -155,12 +226,27 @@ int main(int argc, char ** argv)
 	buf[0x1f6] = sys_size >> 16;
 	buf[0x1f7] = sys_size >> 24;
 
+	crc = partial_crc32(buf, i, crc);
 	if (fwrite(buf, 1, i, stdout) != i)
 		die("Writing setup failed");
 
 	/* Copy the kernel code */
+	crc = partial_crc32(kernel, sz, crc);
 	if (fwrite(kernel, 1, sz, stdout) != sz)
 		die("Writing kernel failed");
+
+	/* Add padding leaving 4 bytes for the checksum */
+	while (sz++ < (sys_size*16) - 4) {
+		crc = partial_crc32_one('\0', crc);
+		if (fwrite("\0", 1, 1, stdout) != 1)
+			die("Writing padding failed");
+	}
+
+	/* Write the CRC */
+	fprintf(stderr, "CRC %lx\n", crc);
+	if (fwrite(&crc, 1, 4, stdout) != 4)
+		die("Writing CRC failed");
+
 	close(fd);
 
 	/* Everything is OK */
-- 
1.5.4

[PATCHv2 3/3] x86: bump image header to version 2.08.

[Ian Campbell]

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
---
 arch/x86/boot/header.S |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 8471658..40c91bb 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -120,7 +120,7 @@ _start:
 	# Part 2 of the header, from the old setup.S
 
 		.ascii	"HdrS"		# header signature
-		.word	0x0207		# header version number (>= 0x0105)
+		.word	0x0208		# header version number (>= 0x0105)
 					# or else old loadlin-1.5 will fail)
 		.globl realmode_swtch
 realmode_swtch:	.word	0, 0		# default_switch, SETUPSEG
-- 
1.5.4

Re: [PATCHv2 2/3] x86: add a crc32 checksum to the kernel image.

[H. Peter Anvin]

Ian Campbell wrote:
> Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: H. Peter Anvin <hpa@zytor.com>
> ---
>  Documentation/i386/boot.txt |    7 +++
>  arch/x86/boot/tools/build.c |   88 ++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 94 insertions(+), 1 deletions(-)
> 
> diff --git a/Documentation/i386/boot.txt b/Documentation/i386/boot.txt
> index b5f5ba1..b567fb5 100644
> --- a/Documentation/i386/boot.txt
> +++ b/Documentation/i386/boot.txt
> @@ -531,6 +531,13 @@ Protocol:	2.08+
>  
>    The length of the compressed payload.
>  
> +**** THE IMAGE CHECKSUM
> +
> +The CRC-32 is calculated over the entire file using an initial
> +remainder of 0xffffffff.  The checksum is appended to the file;
> +therefore the CRC of the file up to the limit specified in the syssize
> +field of the header is always 0.
> +


This doesn't specify that the image checksum is present only for boot 
protocol 2.08 or later, nor does it specify the characteristic 
polynomial (for CRC32 in particular, I realize the Autodin II polynomial 
is pretty close to universal, but it should at least state that it is used.)

>  **** THE KERNEL COMMAND LINE
>  
>  The kernel command line has become an important way for the boot
> diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c
> index b424874..2ba22e8 100644
> --- a/arch/x86/boot/tools/build.c
> +++ b/arch/x86/boot/tools/build.c
> @@ -50,6 +50,75 @@ typedef unsigned long  u32;
>  u8 buf[SETUP_SECT_MAX*512];
>  int is_big_kernel;
>  
> +/*----------------------------------------------------------------------*/
> +
> +static const unsigned int crctab32[] = {

Really should be "u32" rather than "unsigned int".

> +	0x00000000U, 0x77073096U, 0xee0e612cU, 0x990951baU, 0x076dc419U,

The "U"s are redundant.

	-hpa

Re: [PATCHv2 2/3] x86: add a crc32 checksum to the kernel image.

[Ian Campbell]

On Wed, 2008-02-06 at 13:06 -0800, H. Peter Anvin wrote:
[...some comments...]

I fixed all of those up.

Thanks,
Ian.

---

x86: add a crc32 checksum to the kernel image.

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
---
 Documentation/i386/boot.txt |    8 ++++
 arch/x86/boot/tools/build.c |   88 ++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 95 insertions(+), 1 deletions(-)

diff --git a/Documentation/i386/boot.txt b/Documentation/i386/boot.txt
index b5f5ba1..05c24df 100644
--- a/Documentation/i386/boot.txt
+++ b/Documentation/i386/boot.txt
@@ -531,6 +531,14 @@ Protocol:	2.08+
 
   The length of the compressed payload.
 
+**** THE IMAGE CHECKSUM
+
+From boot protocol version 2.08 onwards the CRC-32 is calculated over
+the entire file using the characteristic polynomial 0x04C11DB7 and an
+initial remainder of 0xffffffff.  The checksum is appended to the
+file; therefore the CRC of the file up to the limit specified in the
+syssize field of the header is always 0.
+
 **** THE KERNEL COMMAND LINE
 
 The kernel command line has become an important way for the boot
diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c
index b424874..44dc192 100644
--- a/arch/x86/boot/tools/build.c
+++ b/arch/x86/boot/tools/build.c
@@ -50,6 +50,75 @@ typedef unsigned long  u32;
 u8 buf[SETUP_SECT_MAX*512];
 int is_big_kernel;
 
+/*----------------------------------------------------------------------*/
+
+static const u32 crctab32[] = {
+	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
+	0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
+	0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
+	0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
+	0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
+	0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
+	0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
+	0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
+	0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
+	0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
+	0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
+	0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
+	0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
+	0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
+	0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
+	0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
+	0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
+	0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
+	0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
+	0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
+	0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
+	0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
+	0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
+	0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+	0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
+	0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
+	0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
+	0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
+	0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
+	0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
+	0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
+	0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
+	0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
+	0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
+	0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
+	0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
+	0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
+	0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
+	0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
+	0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
+	0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
+	0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
+	0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
+	0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
+	0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
+	0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
+	0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
+	0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+	0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
+	0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
+	0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
+	0x2d02ef8d
+};
+
+static u32 partial_crc32_one(u8 c, u32 crc)
+{
+	return crctab32[(crc ^ c) & 0xff] ^ (crc >> 8);
+}
+
+static u32 partial_crc32(const u8 *s, int len, u32 crc)
+{
+	while (len--)
+		crc = partial_crc32_one(*s++, crc);
+	return crc;
+}
+
 static void die(const char * str, ...)
 {
 	va_list args;
@@ -74,6 +143,7 @@ int main(int argc, char ** argv)
 	FILE *file;
 	int fd;
 	void *kernel;
+	u32 crc = 0xffffffffUL;
 
 	if (argc > 2 && !strcmp(argv[1], "-b"))
 	  {
@@ -144,7 +214,8 @@ int main(int argc, char ** argv)
 	kernel = mmap(NULL, sz, PROT_READ, MAP_SHARED, fd, 0);
 	if (kernel == MAP_FAILED)
 		die("Unable to mmap '%s': %m", argv[2]);
-	sys_size = (sz + 15) / 16;
+	/* Number of 16-byte paragraphs, including space for a 4-byte CRC */
+	sys_size = (sz + 15 + 4) / 16;
 	if (!is_big_kernel && sys_size > DEF_SYSSIZE)
 		die("System is too big. Try using bzImage or modules.");
 
@@ -155,12 +226,27 @@ int main(int argc, char ** argv)
 	buf[0x1f6] = sys_size >> 16;
 	buf[0x1f7] = sys_size >> 24;
 
+	crc = partial_crc32(buf, i, crc);
 	if (fwrite(buf, 1, i, stdout) != i)
 		die("Writing setup failed");
 
 	/* Copy the kernel code */
+	crc = partial_crc32(kernel, sz, crc);
 	if (fwrite(kernel, 1, sz, stdout) != sz)
 		die("Writing kernel failed");
+
+	/* Add padding leaving 4 bytes for the checksum */
+	while (sz++ < (sys_size*16) - 4) {
+		crc = partial_crc32_one('\0', crc);
+		if (fwrite("\0", 1, 1, stdout) != 1)
+			die("Writing padding failed");
+	}
+
+	/* Write the CRC */
+	fprintf(stderr, "CRC %lx\n", crc);
+	if (fwrite(&crc, 1, 4, stdout) != 4)
+		die("Writing CRC failed");
+
 	close(fd);
 
 	/* Everything is OK */
-- 
1.5.4


-- 
Ian Campbell

Hempstone's Question:
	If you have to travel on the Titanic, why not go first class?