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Commit 09c205af authored by H. Peter Anvin's avatar H. Peter Anvin
Browse files

x86, boot: Define the 2.12 bzImage boot protocol 



Define the 2.12 bzImage boot protocol: add xloadflags and additional
fields to allow the command line, initramfs and struct boot_params to
live above the 4 GiB mark.

The xloadflags now communicates if this is a 64-bit kernel with the
legacy 64-bit entry point and which of the EFI handover entry points
are supported.

Avoid adding new read flags to loadflags because of claimed
bootloaders testing the whole byte for == 1 to determine bzImageness
at least until the issue can be researched further.

This is based on patches by Yinghai Lu and David Woodhouse.

Originally-by: default avatarYinghai Lu <yinghai@kernel.org>
Originally-by: default avatarDavid Woodhouse <dwmw2@infradead.org>
Acked-by: default avatarYinghai Lu <yinghai@kernel.org>
Acked-by: default avatarDavid Woodhouse <dwmw2@infradead.org>
Acked-by: default avatarMatt Fleming <matt.fleming@intel.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1359058816-7615-26-git-send-email-yinghai@kernel.org
Cc: Rob Landley <rob@landley.net>
Cc: Gokul Caushik <caushik1@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joe Millenbach <jmillenbach@gmail.com>
parent 65315d48

Documentation/x86/boot.txt

+26 −1
Original line number Diff line number Diff line
@@ -57,6 +57,10 @@ Protocol 2.10: (Kernel 2.6.31) Added a protocol for relaxed alignment 
Protocol 2.11:	(Kernel 3.6) Added a field for offset of EFI handover

		protocol entry point.



Protocol 2.12:	(Kernel 3.9) Added the xloadflags field and extension fields

	 	to struct boot_params for for loading bzImage and ramdisk

		above 4G in 64bit.



**** MEMORY LAYOUT



The traditional memory map for the kernel loader, used for Image or
@@ -182,7 +186,7 @@ Offset Proto Name Meaning 
0230/4	2.05+	kernel_alignment Physical addr alignment required for kernel

0234/1	2.05+	relocatable_kernel Whether kernel is relocatable or not

0235/1	2.10+	min_alignment	Minimum alignment, as a power of two

0236/2	N/A	pad3		Unused

0236/2	2.12+	xloadflags	Boot protocol option flags

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
@@ -582,6 +586,27 @@ Protocol: 2.10+ 
  misaligned kernel.  Therefore, a loader should typically try each

  power-of-two alignment from kernel_alignment down to this alignment.



Field name:     xloadflags

Type:           read

Offset/size:    0x236/2

Protocol:       2.12+



  This field is a bitmask.



  Bit 0 (read):	XLF_KERNEL_64

	- If 1, this kernel has the legacy 64-bit entry point at 0x200.



  Bit 1 (read): XLF_CAN_BE_LOADED_ABOVE_4G

        - If 1, kernel/boot_params/cmdline/ramdisk can be above 4G.



  Bit 2 (read):	XLF_EFI_HANDOVER_32

	- If 1, the kernel supports the 32-bit EFI handoff entry point

          given at handover_offset.



  Bit 3 (read): XLF_EFI_HANDOVER_64

	- If 1, the kernel supports the 64-bit EFI handoff entry point

          given at handover_offset + 0x200.



Field name:	cmdline_size

Type:		read

Offset/size:	0x238/4

Documentation/x86/zero-page.txt

+4 −0
Original line number Diff line number Diff line
@@ -19,6 +19,9 @@ Offset Proto Name Meaning 
090/010	ALL	hd1_info	hd1 disk parameter, OBSOLETE!!

0A0/010	ALL	sys_desc_table	System description table (struct sys_desc_table)

0B0/010	ALL	olpc_ofw_header	OLPC's OpenFirmware CIF and friends

0C0/004	ALL	ext_ramdisk_image ramdisk_image high 32bits

0C4/004	ALL	ext_ramdisk_size  ramdisk_size high 32bits

0C8/004	ALL	ext_cmd_line_ptr  cmd_line_ptr high 32bits

140/080	ALL	edid_info	Video mode setup (struct edid_info)

1C0/020	ALL	efi_info	EFI 32 information (struct efi_info)

1E0/004	ALL	alk_mem_k	Alternative mem check, in KB
@@ -27,6 +30,7 @@ Offset Proto Name Meaning 
1E9/001	ALL	eddbuf_entries	Number of entries in eddbuf (below)

1EA/001	ALL	edd_mbr_sig_buf_entries	Number of entries in edd_mbr_sig_buffer

				(below)

1EF/001	ALL	sentinel	Used to detect broken bootloaders

290/040	ALL	edd_mbr_sig_buffer EDD MBR signatures

2D0/A00	ALL	e820_map	E820 memory map table

				(array of struct e820entry)

arch/x86/boot/header.S

+29 −10
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <asm/e820.h>

#include <asm/page_types.h>

#include <asm/setup.h>

#include <asm/bootparam.h>

#include "boot.h"

#include "voffset.h"

#include "zoffset.h"
@@ -255,6 +256,9 @@ section_table: 
	# header, from the old boot sector.



	.section ".header", "a"

	.globl	sentinel

sentinel:	.byte 0xff, 0xff        /* Used to detect broken loaders */



	.globl	hdr

hdr:

setup_sects:	.byte 0			/* Filled in by build.c */
@@ -279,7 +283,7 @@ _start: 
	# Part 2 of the header, from the old setup.S



		.ascii	"HdrS"		# header signature

		.word	0x020b		# header version number (>= 0x0105)

		.word	0x020c		# header version number (>= 0x0105)

					# or else old loadlin-1.5 will fail)

		.globl realmode_swtch

realmode_swtch:	.word	0, 0		# default_switch, SETUPSEG
@@ -297,13 +301,7 @@ type_of_loader: .byte 0 # 0 means ancient bootloader, newer 


# flags, unused bits must be zero (RFU) bit within loadflags

loadflags:

LOADED_HIGH	= 1			# If set, the kernel is loaded high

CAN_USE_HEAP	= 0x80			# If set, the loader also has set

					# heap_end_ptr to tell how much

					# space behind setup.S can be used for

					# heap purposes.

					# Only the loader knows what is free

		.byte	LOADED_HIGH

		.byte	LOADED_HIGH	# The kernel is to be loaded high



setup_move_size: .word  0x8000		# size to move, when setup is not

					# loaded at 0x90000. We will move setup
@@ -369,7 +367,23 @@ relocatable_kernel: .byte 1 
relocatable_kernel:    .byte 0

#endif

min_alignment:		.byte MIN_KERNEL_ALIGN_LG2	# minimum alignment

pad3:			.word 0



xloadflags:

#ifdef CONFIG_X86_64

# define XLF0 XLF_KERNEL_64			/* 64-bit kernel */

#else

# define XLF0 0

#endif

#ifdef CONFIG_EFI_STUB

# ifdef CONFIG_X86_64

#  define XLF23 XLF_EFI_HANDOVER_64		/* 64-bit EFI handover ok */

# else

#  define XLF23 XLF_EFI_HANDOVER_32		/* 32-bit EFI handover ok */

# endif

#else

# define XLF23 0

#endif

			.word XLF0 | XLF23



cmdline_size:   .long   COMMAND_LINE_SIZE-1     #length of the command line,

                                                #added with boot protocol
@@ -397,8 +411,13 @@ pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr 
#define INIT_SIZE VO_INIT_SIZE

#endif

init_size:		.long INIT_SIZE		# kernel initialization size

handover_offset:	.long 0x30		# offset to the handover

handover_offset:

#ifdef CONFIG_EFI_STUB

  			.long 0x30		# offset to the handover

						# protocol entry point

#else

			.long 0

#endif



# End of setup header #####################################################

arch/x86/boot/setup.ld

+1 −1
Original line number Diff line number Diff line
@@ -13,7 +13,7 @@ SECTIONS 
	.bstext		: { *(.bstext) }

	.bsdata		: { *(.bsdata) }



	. = 497;

	. = 495;

	.header		: { *(.header) }

	.entrytext	: { *(.entrytext) }

	.inittext	: { *(.inittext) }

arch/x86/include/uapi/asm/bootparam.h

+46 −17
Original line number Diff line number Diff line 
#ifndef _ASM_X86_BOOTPARAM_H

#define _ASM_X86_BOOTPARAM_H



/* setup_data types */

#define SETUP_NONE			0

#define SETUP_E820_EXT			1

#define SETUP_DTB			2

#define SETUP_PCI			3



/* ram_size flags */

#define RAMDISK_IMAGE_START_MASK	0x07FF

#define RAMDISK_PROMPT_FLAG		0x8000

#define RAMDISK_LOAD_FLAG		0x4000



/* loadflags */

#define LOADED_HIGH	(1<<0)

#define QUIET_FLAG	(1<<5)

#define KEEP_SEGMENTS	(1<<6)

#define CAN_USE_HEAP	(1<<7)



/* xloadflags */

#define XLF_KERNEL_64			(1<<0)

#define XLF_CAN_BE_LOADED_ABOVE_4G	(1<<1)

#define XLF_EFI_HANDOVER_32		(1<<2)

#define XLF_EFI_HANDOVER_64		(1<<3)



#ifndef __ASSEMBLY__



#include <linux/types.h>

#include <linux/screen_info.h>

#include <linux/apm_bios.h>
@@ -9,12 +34,6 @@ 
#include <asm/ist.h>

#include <video/edid.h>



/* setup data types */

#define SETUP_NONE			0

#define SETUP_E820_EXT			1

#define SETUP_DTB			2

#define SETUP_PCI			3



/* extensible setup data list node */

struct setup_data {

	__u64 next;
@@ -28,9 +47,6 @@ struct setup_header { 
	__u16	root_flags;

	__u32	syssize;

	__u16	ram_size;

#define RAMDISK_IMAGE_START_MASK	0x07FF

#define RAMDISK_PROMPT_FLAG		0x8000

#define RAMDISK_LOAD_FLAG		0x4000

	__u16	vid_mode;

	__u16	root_dev;

	__u16	boot_flag;
@@ -42,10 +58,6 @@ struct setup_header { 
	__u16	kernel_version;

	__u8	type_of_loader;

	__u8	loadflags;

#define LOADED_HIGH	(1<<0)

#define QUIET_FLAG	(1<<5)

#define KEEP_SEGMENTS	(1<<6)

#define CAN_USE_HEAP	(1<<7)

	__u16	setup_move_size;

	__u32	code32_start;

	__u32	ramdisk_image;
@@ -58,7 +70,8 @@ struct setup_header { 
	__u32	initrd_addr_max;

	__u32	kernel_alignment;

	__u8	relocatable_kernel;

	__u8	_pad2[3];

	__u8	min_alignment;

	__u16	xloadflags;

	__u32	cmdline_size;

	__u32	hardware_subarch;

	__u64	hardware_subarch_data;
@@ -106,7 +119,10 @@ struct boot_params { 
	__u8  hd1_info[16];	/* obsolete! */		/* 0x090 */

	struct sys_desc_table sys_desc_table;		/* 0x0a0 */

	struct olpc_ofw_header olpc_ofw_header;		/* 0x0b0 */

	__u8  _pad4[128];				/* 0x0c0 */

	__u32 ext_ramdisk_image;			/* 0x0c0 */

	__u32 ext_ramdisk_size;				/* 0x0c4 */

	__u32 ext_cmd_line_ptr;				/* 0x0c8 */

	__u8  _pad4[116];				/* 0x0cc */

	struct edid_info edid_info;			/* 0x140 */

	struct efi_info efi_info;			/* 0x1c0 */

	__u32 alt_mem_k;				/* 0x1e0 */
@@ -115,7 +131,20 @@ struct boot_params { 
	__u8  eddbuf_entries;				/* 0x1e9 */

	__u8  edd_mbr_sig_buf_entries;			/* 0x1ea */

	__u8  kbd_status;				/* 0x1eb */

	__u8  _pad6[5];					/* 0x1ec */

	__u8  _pad5[3];					/* 0x1ec */

	/*

	 * The sentinel is set to a nonzero value (0xff) in header.S.

	 *

	 * A bootloader is supposed to only take setup_header and put

	 * it into a clean boot_params buffer. If it turns out that

	 * it is clumsy or too generous with the buffer, it most

	 * probably will pick up the sentinel variable too. The fact

	 * that this variable then is still 0xff will let kernel

	 * know that some variables in boot_params are invalid and

	 * kernel should zero out certain portions of boot_params.

	 */

	__u8  sentinel;					/* 0x1ef */

	__u8  _pad6[1];					/* 0x1f0 */

	struct setup_header hdr;    /* setup header */	/* 0x1f1 */

	__u8  _pad7[0x290-0x1f1-sizeof(struct setup_header)];

	__u32 edd_mbr_sig_buffer[EDD_MBR_SIG_MAX];	/* 0x290 */
@@ -134,6 +163,6 @@ enum { 
	X86_NR_SUBARCHS,

};





#endif /* __ASSEMBLY__ */



#endif /* _ASM_X86_BOOTPARAM_H */