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|
; $Id: bootsector-pae.asm $
;; @file
; Bootsector that switches the CPU info PAE mode.
;
;
; Copyright (C) 2007-2022 Oracle and/or its affiliates.
;
; This file is part of VirtualBox base platform packages, as
; available from https://www.virtualbox.org.
;
; This program is free software; you can redistribute it and/or
; modify it under the terms of the GNU General Public License
; as published by the Free Software Foundation, in version 3 of the
; License.
;
; This program is distributed in the hope that it will be useful, but
; WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
; General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program; if not, see <https://www.gnu.org/licenses>.
;
; The contents of this file may alternatively be used under the terms
; of the Common Development and Distribution License Version 1.0
; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
; in the VirtualBox distribution, in which case the provisions of the
; CDDL are applicable instead of those of the GPL.
;
; You may elect to license modified versions of this file under the
; terms and conditions of either the GPL or the CDDL or both.
;
; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
;
%include "iprt/asmdefs.mac"
%include "iprt/x86.mac"
%include "VBox/bios.mac"
;; The boot sector load address.
%define BS_ADDR 0x7c00
%define PDP_ADDR 0x9000
%define PD_ADDR 0xa000
BITS 16
start:
; Start with a jump just to follow the convention.
jmp short the_code
nop
times 3ah db 0
the_code:
cli
xor edx, edx
mov ds, dx ; Use 0 based addresses
;
; Create a paging hierarchy
;
mov cx, 4
xor esi, esi ; physical address
mov ebx, PDP_ADDR
mov edi, PD_ADDR
pdptr_loop:
; The page directory pointer entry.
mov dword [ebx], edi
or word [bx], X86_PDPE_P
mov dword [ebx + 4], edx
; The page directory.
pd_loop:
mov dword [edi], esi
or word [di], X86_PDE4M_P | X86_PDE4M_RW | X86_PDE4M_PS
mov dword [edi + 4], 0
add esi, 0x00200000 ; 2MB
add di, 8
test di, 0fffh
jnz pd_loop
add bx, 8
loop pdptr_loop
;
; Switch to protected mode.
;
lgdt [(gdtr - start) + BS_ADDR]
lidt [(idtr_null - start) + BS_ADDR]
mov eax, PDP_ADDR
mov cr3, eax
mov eax, cr4
or eax, X86_CR4_PAE | X86_CR4_PSE
mov cr4, eax
mov eax, cr0
or eax, X86_CR0_PE | X86_CR0_PG
mov cr0, eax
jmp far 0x0008:((code32_start - start) + BS_ADDR) ; 8=32-bit CS
BITS 32
code32_start:
mov ax, 0x10
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov ax, 0x18
mov es, ax
mov esp, 0x80000
; eye catchers
mov eax, 0xCafeBabe
mov ebx, eax
mov ecx, eax
mov edx, eax
mov edi, eax
mov esi, eax
mov ebp, eax
;
; Boch shutdown request.
;
mov bl, 64
mov dx, VBOX_BIOS_SHUTDOWN_PORT
mov ax, VBOX_BIOS_OLD_SHUTDOWN_PORT
retry:
mov ecx, 8
mov esi, (szShutdown - start) + BS_ADDR
rep outsb
xchg dx, ax ; alternate between the new (VBox) and old (Bochs) ports.
dec bl
jnz retry
; Shutdown failed!
hlt_again:
hlt
cli
jmp hlt_again
;
; The GDT.
;
align 8, db 0
gdt:
dw 0, 0, 0, 0 ; null selector
dw 0xffff, 0, 0x9b00, 0x00cf ; 32 bit flat code segment (0x08)
dw 0xffff, 0, 0x9300, 0x00cf ; 32 bit flat data segment (0x10)
dw 0xffff, 0, 0x9300, 0x00cf ; 32 bit flat stack segment (0x18)
gdtr:
dw 8*4-1 ; limit 15:00
dw (gdt - start) + BS_ADDR ; base 15:00
db 0 ; base 23:16
db 0 ; unused
idtr_null:
dw 0 ; limit 15:00
dw (gdt - start) + BS_ADDR ; base 15:00
db 0 ; base 23:16
db 0 ; unused
szShutdown:
db 'Shutdown', 0
;
; Padd the remainder of the sector with zeros and
; end it with the dos signature.
;
padding:
times 510 - (padding - start) db 0
db 055h, 0aah
|
