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/* ----------------------------------------------------------------------- *
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright 2007 rPath, Inc. - All Rights Reserved
*
* This file is part of the Linux kernel, and is made available under
* the terms of the GNU General Public License version 2.
*
* ----------------------------------------------------------------------- */
/*
* arch/i386/boot/pmjump.S
*
* The actual transition into protected mode
*/
#include <asm/boot.h>
#include <asm/segment.h>
.text
.globl protected_mode_jump
.type protected_mode_jump, @function
.code16
/*
* void protected_mode_jump(u32 entrypoint, u32 bootparams);
*/
protected_mode_jump:
movl %edx, %esi # Pointer to boot_params table
xorl %ebx, %ebx
movw %cs, %bx
shll $4, %ebx
addl %ebx, 2f
movw $__BOOT_DS, %cx
movw $__BOOT_TSS, %di
movl %cr0, %edx
orb $1, %dl # Protected mode (PE) bit
movl %edx, %cr0
jmp 1f # Short jump to serialize on 386/486
1:
# Transition to 32-bit mode
.byte 0x66, 0xea # ljmpl opcode
2: .long in_pm32 # offset
.word __BOOT_CS # segment
.size protected_mode_jump, .-protected_mode_jump
.code32
.type in_pm32, @function
in_pm32:
# Set up data segments for flat 32-bit mode
movl %ecx, %ds
movl %ecx, %es
movl %ecx, %fs
movl %ecx, %gs
movl %ecx, %ss
# The 32-bit code sets up its own stack, but this way we do have
# a valid stack if some debugging hack wants to use it.
addl %ebx, %esp
# Set up TR to make Intel VT happy
ltr %di
# Clear registers to allow for future extensions to the
# 32-bit boot protocol
xorl %ecx, %ecx
xorl %edx, %edx
xorl %ebx, %ebx
xorl %ebp, %ebp
xorl %edi, %edi
# Set up LDTR to make Intel VT happy
lldt %cx
jmpl *%eax # Jump to the 32-bit entrypoint
.size in_pm32, .-in_pm32
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