/* ----------------------------------------------------------------------- *
   *
   *   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.
   *
   * ----------------------------------------------------------------------- */
  
  /*

   * The actual transition into protected mode
   */
  
  #include <asm/boot.h>

  #include <asm/processor-flags.h>

  #include <asm/segment.h>

  #include <linux/linkage.h>

  
  	.text

  	.code16
  
  /*
   * void protected_mode_jump(u32 entrypoint, u32 bootparams);
   */

  GLOBAL(protected_mode_jump)

  	movl	%edx, %esi		# Pointer to boot_params table

  
  	xorl	%ebx, %ebx
  	movw	%cs, %bx
  	shll	$4, %ebx
  	addl	%ebx, 2f

  	jmp	1f			# Short jump to serialize on 386/486
  1:

  	movw	$__BOOT_DS, %cx

  	movw	$__BOOT_TSS, %di

  
  	movl	%cr0, %edx

  	orb	$X86_CR0_PE, %dl	# Protected mode

  	movl	%edx, %cr0

  	# Transition to 32-bit mode

  	.byte	0x66, 0xea		# ljmpl opcode

  2:	.long	in_pm32			# offset

  	.word	__BOOT_CS		# segment

  ENDPROC(protected_mode_jump)

  
  	.code32

  	.section ".text32","ax"

  GLOBAL(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

  ENDPROC(in_pm32)