Subversion Repositories HelenOS

#
# 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