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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