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#

# Copyright (C) 2001-2004 Jakub Jermar

# All rights reserved.

#

# Redistribution and use in source and binary forms, with or without

# modification, are permitted provided that the following conditions

# are met:

#

# - Redistributions of source code must retain the above copyright

#   notice, this list of conditions and the following disclaimer.

# - Redistributions in binary form must reproduce the above copyright

#   notice, this list of conditions and the following disclaimer in the

#   documentation and/or other materials provided with the distribution.

# - The name of the author may not be used to endorse or promote products

#   derived from this software without specific prior written permission.

#

# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#

.section K_TEXT_START

.global kernel_image_start

.code16

#

# This is where we require any SPARTAN-kernel-compatible boot loader

# to pass control in real mode.

#

# Protected mode tables are statically initialised during compile

# time. So we can just load the respective table registers and

# switch to protected mode.

#

kernel_image_start:

	cli

	xorw %ax,%ax

	movw %ax,%ds

	movw %ax,%ss			# initialize stack segment register

	movl $0x7c00,%esp		# initialize stack pointer

	call memmap_arch_init

	lgdt gdtr			# initialize Global Descriptor Table register

	lidt idtr			# initialize Interrupt Descriptor Table register

	movl %cr0,%eax

	orl $0x1,%eax

	movl %eax,%cr0			# switch to protected mode

	jmpl $8,$meeting_point

meeting_point:

.code32

	movw $16,%ax

	movw %ax,%es

	movw %ax,%gs

	movw %ax,%fs

	movw %ax,%ds			# kernel data + stack

	movw %ax,%ss

	call map_kernel			# map kernel and turn paging on

	call main_bsp			# never returns

	cli

	hlt

.global map_kernel

map_kernel:

	#

	# Here we setup mapping for both the unmapped and mapped sections of the kernel.

	# For simplicity, we set only one 4M page for 0x00000000 and one for 0x80000000.

	#

	movl %cr4, %ecx

	orl $(1<<4), %ecx

	movl %ecx, %cr4				# turn PSE on

	movl $((1<<7)|(1<<0)), %eax

	movl %eax, page_directory		# mapping 0x00000000 => 0x00000000

	movl $(page_directory+(4096/2)), %edx

	movl %eax, (%edx)			# mapping 0x80000000 => 0x00000000

	leal page_directory, %eax

	movl %eax, %cr3

	# turn paging on

	movl %cr0, %ebx

	orl $(1<<31), %ebx

	movl %ebx, %cr0

	ret

.section K_DATA_START

.align 4096

page_directory:

	.space 4096, 0