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Commit e5371ac5 authored by Rusty Russell's avatar Rusty Russell Committed by Linus Torvalds
Browse files

update boot spec to 2.07 



Updates for version 2.07 of the boot protocol.  This includes:

load_flags.KEEP_SEGMENTS- flag to request/inhibit segment reloads
hardware_subarch	- what subarchitecture we're booting under
hardware_subarch_data	- per-architecture data

The intention of these changes is to make booting a paravirtualized
kernel work via the normal Linux boot protocol.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Acked-by: default avatarH. Peter Anvin <hpa@zytor.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 55b70a03

Documentation/i386/boot.txt

+33 −1
Original line number Diff line number Diff line
@@ -168,6 +168,8 @@ Offset Proto Name Meaning 
0234/1	2.05+	relocatable_kernel Whether kernel is relocatable or not

0235/3	N/A	pad2		Unused

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



(1) For backwards compatibility, if the setup_sects field contains 0, the

    real value is 4.
@@ -204,7 +206,7 @@ boot loaders can ignore those fields. 


The byte order of all fields is littleendian (this is x86, after all.)



Field name:	setup_secs

Field name:	setup_sects

Type:		read

Offset/size:	0x1f1/1

Protocol:	ALL
@@ -356,6 +358,13 @@ Protocol: 2.00+ 
	- If 0, the protected-mode code is loaded at 0x10000.

	- If 1, the protected-mode code is loaded at 0x100000.



  Bit 6 (write): KEEP_SEGMENTS

	Protocol: 2.07+

	- if 0, reload the segment registers in the 32bit entry point.

	- if 1, do not reload the segment registers in the 32bit entry point.

		Assume that %cs %ds %ss %es are all set to flat segments with

		a base of 0 (or the equivalent for their environment).



  Bit 7 (write): CAN_USE_HEAP

	Set this bit to 1 to indicate that the value entered in the

	heap_end_ptr is valid.  If this field is clear, some setup code
@@ -480,6 +489,29 @@ Protocol: 2.06+ 
  cmdline_size characters. With protocol version 2.05 and earlier, the

  maximum size was 255.



Field name:	hardware_subarch

Type:		write

Offset/size:	0x23c/4

Protocol:	2.07+



  In a paravirtualized environment the hardware low level architectural

  pieces such as interrupt handling, page table handling, and

  accessing process control registers needs to be done differently.



  This field allows the bootloader to inform the kernel we are in one

  one of those environments.



  0x00000000	The default x86/PC environment

  0x00000001	lguest

  0x00000002	Xen



Field name:	hardware_subarch_data

Type:		write

Offset/size:	0x240/8

Protocol:	2.07+



  A pointer to data that is specific to hardware subarch





**** THE KERNEL COMMAND LINE

arch/x86/kernel/asm-offsets_32.c

+7 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <asm/fixmap.h>

#include <asm/processor.h>

#include <asm/thread_info.h>

#include <asm/bootparam.h>

#include <asm/elf.h>



#include <xen/interface/xen.h>
@@ -146,4 +147,10 @@ void foo(void) 
	OFFSET(LGUEST_PAGES_regs_errcode, lguest_pages, regs.errcode);

	OFFSET(LGUEST_PAGES_regs, lguest_pages, regs);

#endif



	BLANK();

	OFFSET(BP_scratch, boot_params, scratch);

	OFFSET(BP_loadflags, boot_params, hdr.loadflags);

	OFFSET(BP_hardware_subarch, boot_params, hdr.hardware_subarch);

	OFFSET(BP_version, boot_params, hdr.version);

}

include/asm-x86/bootparam.h

+7 −2
Original line number Diff line number Diff line
@@ -28,8 +28,9 @@ struct setup_header { 
	u16	kernel_version;

	u8	type_of_loader;

	u8	loadflags;

#define LOADED_HIGH	0x01

#define CAN_USE_HEAP	0x80

#define LOADED_HIGH	(1<<0)

#define KEEP_SEGMENTS	(1<<6)

#define CAN_USE_HEAP	(1<<7)

	u16	setup_move_size;

	u32	code32_start;

	u32	ramdisk_image;
@@ -41,6 +42,10 @@ struct setup_header { 
	u32	initrd_addr_max;

	u32	kernel_alignment;

	u8	relocatable_kernel;

	u8	_pad2[3];

	u32	cmdline_size;

	u32	hardware_subarch;

	u64	hardware_subarch_data;

} __attribute__((packed));



struct sys_desc_table {