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Commit a24e7851 authored by Rusty Russell's avatar Rusty Russell Committed by Linus Torvalds
Browse files

i386: paravirt boot sequence 



This patch uses the updated boot protocol to do paravirtualized boot.
If the boot version is >= 2.07, then it will do two things:

 1. Check the bootparams loadflags to see if we should reload the
    segment registers and clear interrupts.  This is appropriate
    for normal native boot and some paravirtualized environments, but
    inapproprate for others.

 2. Check the hardware architecture, and dispatch to the appropriate
    kernel entrypoint.  If the bootloader doesn't set this, then we
    simply do the normal boot sequence.

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>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 214541d1

arch/x86/boot/compressed/head_32.S

+13 −2
Original line number Diff line number Diff line
@@ -27,13 +27,22 @@ 
#include <asm/segment.h>

#include <asm/page.h>

#include <asm/boot.h>

#include <asm/asm-offsets.h>



.section ".text.head","ax",@progbits

	.globl startup_32



startup_32:

	cld

	cli

	/* check to see if KEEP_SEGMENTS flag is meaningful */

	cmpw $0x207, BP_version(%esi)

	jb 1f



	/* test KEEP_SEGMENTS flag to see if the bootloader is asking

	 * us to not reload segments */

	testb $(1<<6), BP_loadflags(%esi)

	jnz 2f



1:	cli

	movl $(__BOOT_DS),%eax

	movl %eax,%ds

	movl %eax,%es
@@ -41,6 +50,8 @@ startup_32: 
	movl %eax,%gs

	movl %eax,%ss



2:	cld



/* Calculate the delta between where we were compiled to run

 * at and where we were actually loaded at.  This can only be done

 * with a short local call on x86.  Nothing  else will tell us what

arch/x86/boot/compressed/misc_32.c

+3 −0
Original line number Diff line number Diff line
@@ -247,6 +247,9 @@ static void putstr(const char *s) 
	int x,y,pos;

	char c;



	if (RM_SCREEN_INFO.orig_video_mode == 0 && lines == 0 && cols == 0)

		return;



	x = RM_SCREEN_INFO.orig_x;

	y = RM_SCREEN_INFO.orig_y;

arch/x86/boot/header.S

+6 −1
Original line number Diff line number Diff line
@@ -119,7 +119,7 @@ _start: 
	# Part 2 of the header, from the old setup.S



		.ascii	"HdrS"		# header signature

		.word	0x0206		# header version number (>= 0x0105)

		.word	0x0207		# header version number (>= 0x0105)

					# or else old loadlin-1.5 will fail)

		.globl realmode_swtch

realmode_swtch:	.word	0, 0		# default_switch, SETUPSEG
@@ -214,6 +214,11 @@ cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line, 
                                                #added with boot protocol

                                                #version 2.06



hardware_subarch:	.long 0			# subarchitecture, added with 2.07

						# default to 0 for normal x86 PC



hardware_subarch_data:	.quad 0



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



	.section ".inittext", "ax"

arch/x86/kernel/head_32.S

+41 −3
Original line number Diff line number Diff line
@@ -79,22 +79,30 @@ INIT_MAP_BEYOND_END = BOOTBITMAP_SIZE + (PAGE_TABLE_SIZE + ALLOCATOR_SLOP)*PAGE_ 
 */

.section .text.head,"ax",@progbits

ENTRY(startup_32)

	/* check to see if KEEP_SEGMENTS flag is meaningful */

	cmpw $0x207, BP_version(%esi)

	jb 1f



	/* test KEEP_SEGMENTS flag to see if the bootloader is asking

		us to not reload segments */

	testb $(1<<6), BP_loadflags(%esi)

	jnz 2f



/*

 * Set segments to known values.

 */

	cld

	lgdt boot_gdt_descr - __PAGE_OFFSET

1:	lgdt boot_gdt_descr - __PAGE_OFFSET

	movl $(__BOOT_DS),%eax

	movl %eax,%ds

	movl %eax,%es

	movl %eax,%fs

	movl %eax,%gs

2:



/*

 * Clear BSS first so that there are no surprises...

 * No need to cld as DF is already clear from cld above...

 */

	cld

	xorl %eax,%eax

	movl $__bss_start - __PAGE_OFFSET,%edi

	movl $__bss_stop - __PAGE_OFFSET,%ecx
@@ -128,6 +136,35 @@ ENTRY(startup_32) 
	movsl

1:



#ifdef CONFIG_PARAVIRT

	cmpw $0x207, (boot_params + BP_version - __PAGE_OFFSET)

	jb default_entry



	/* Paravirt-compatible boot parameters.  Look to see what architecture

		we're booting under. */

	movl (boot_params + BP_hardware_subarch - __PAGE_OFFSET), %eax

	cmpl $num_subarch_entries, %eax

	jae bad_subarch



	movl subarch_entries - __PAGE_OFFSET(,%eax,4), %eax

	subl $__PAGE_OFFSET, %eax

	jmp *%eax



bad_subarch:

WEAK(lguest_entry)

WEAK(xen_entry)

	/* Unknown implementation; there's really

	   nothing we can do at this point. */

	ud2a

.data

subarch_entries:

	.long default_entry		/* normal x86/PC */

	.long lguest_entry		/* lguest hypervisor */

	.long xen_entry			/* Xen hypervisor */

num_subarch_entries = (. - subarch_entries) / 4

.previous

#endif /* CONFIG_PARAVIRT */



/*

 * Initialize page tables.  This creates a PDE and a set of page

 * tables, which are located immediately beyond _end.  The variable
@@ -140,6 +177,7 @@ ENTRY(startup_32) 
 */

page_pde_offset = (__PAGE_OFFSET >> 20);



default_entry:

	movl $(pg0 - __PAGE_OFFSET), %edi

	movl $(swapper_pg_dir - __PAGE_OFFSET), %edx

	movl $0x007, %eax			/* 0x007 = PRESENT+RW+USER */