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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

	mov $0x80000000, %eax  

	cpuid

	cmp $0x80000000, %eax 	# any function > 80000000h?

	jbe no_long_mode

	mov $0x80000001, %eax	# Extended function code 80000001

	cpuid

	bt $29, %edx 		# Test if long mode is supported.

	jnc no_long_mode

# Fill out GDTR.base, IDTR.base

	leal gdtr, %eax

	movl gdt_addr, %ebx

	movl %ebx, 2(%eax)

	movl idt_addr, %ebx

	leal idtr, %eax

	movl %ebx, 2(%eax)

# Load gdtr, idtr	

	lgdt gdtr

	lidt idtr

	mov $1, %eax    # Enable protected mode (CR0.PE = 1)

	mov %eax, %cr0 

	jmpl $8, $now_in_prot

now_in_prot:

no_long_mode:

1:

	jmp 1b

.section K_DATA_START	

.align 4096

page_directory:

	.space 4096, 0

gdt_addr:	

	.quad gdt + 0x80000000

idt_addr:	

	.quad idt + 0x80000000