source: mainline/arch/ia32/src/boot/boot.S@ 6401f79

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since 6401f79 was f6297e0, checked in by Martin Decky <martin@…>, 20 years ago

proper way of initializing GDT during boot on IA-32, fixes the nasty hack
SMP might be still broken

  • Property mode set to 100644
File size: 3.9 KB
Line 
1#
2# Copyright (C) 2001-2004 Jakub Jermar
3# All rights reserved.
4#
5# Redistribution and use in source and binary forms, with or without
6# modification, are permitted provided that the following conditions
7# are met:
8#
9# - Redistributions of source code must retain the above copyright
10# notice, this list of conditions and the following disclaimer.
11# - Redistributions in binary form must reproduce the above copyright
12# notice, this list of conditions and the following disclaimer in the
13# documentation and/or other materials provided with the distribution.
14# - The name of the author may not be used to endorse or promote products
15# derived from this software without specific prior written permission.
16#
17# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27#
28
29#include <arch/boot/boot.h>
30
31.section K_TEXT_START
32.global kernel_image_start
33
34KTEXT=8
35KDATA=16
36
37.code16
38#
39# This is where we require any SPARTAN-kernel-compatible boot loader
40# to pass control in real mode.
41#
42# Protected mode tables are statically initialised during compile
43# time. So we can just load the respective table registers and
44# switch to protected mode.
45#
46kernel_image_start:
47 cli
48 xorw %ax, %ax
49 movw %ax, %ds
50 movw %ax, %ss # initialize stack segment register
51 movl $BOOTSTRAP_OFFSET - 0x400, %esp # initialize stack pointer
52
53 call memmap_arch_init
54
55 lgdt bsp_bootstrap_gdtr # initialize Global Descriptor Table register
56
57 movl %cr0, %eax
58 orl $0x1, %eax
59 movl %eax, %cr0 # switch to protected mode
60
61 jmpl $KTEXT, $boot_image_start
62
63.code32
64.align 4
65multiboot_header:
66 .long MULTIBOOT_HEADER_MAGIC
67 .long MULTIBOOT_HEADER_FLAGS
68 .long -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS) # checksum
69 .long multiboot_header + BOOT_OFFSET
70 .long unmapped_ktext_start + BOOT_OFFSET
71 .long 0
72 .long 0
73 .long multiboot_image_start + BOOT_OFFSET
74
75boot_image_start:
76 movw $KDATA, %ax
77 movw %ax, %es
78 movw %ax, %gs
79 movw %ax, %fs
80 movw %ax, %ds # kernel data + stack
81 movw %ax, %ss
82
83 call map_kernel # map kernel and turn paging on
84
85 movb $0xd1, %al # enable A20 using the keyboard controller
86 outb %al, $0x64
87 movb $0xdf, %al
88 outb %al, $0x60
89
90 movl $BOOTSTRAP_OFFSET, %esi
91 movl $BOOTSTRAP_OFFSET + BOOT_OFFSET, %edi
92 movl $_hardcoded_kernel_size, %ecx
93 cld
94 rep movsb
95
96 jmp protected
97
98multiboot_image_start:
99 movl BOOTSTRAP_OFFSET - 0x400, %esp # initialize stack pointer
100
101 lgdt gdtr # initialize Global Descriptor Table register
102
103 movw $KDATA, %ax
104 movw %ax, %es
105 movw %ax, %gs
106 movw %ax, %fs
107 movw %ax, %ds # kernel data + stack
108 movw %ax, %ss
109
110 call map_kernel # map kernel and turn paging on
111
112protected:
113 call main_bsp # never returns
114
115 cli
116 hlt
117
118.global map_kernel
119map_kernel:
120 #
121 # Here we setup mapping for both the unmapped and mapped sections of the kernel.
122 # For simplicity, we set only one 4M page for 0x00000000 and one for 0x80000000.
123 #
124 movl %cr4, %ecx
125 orl $(1<<4), %ecx
126 movl %ecx, %cr4 # turn PSE on
127
128 movl $((1<<7)|(1<<0)), %eax
129 movl %eax, page_directory # mapping 0x00000000 => 0x00000000
130
131 movl $(page_directory+(4096/2)), %edx
132 movl %eax, (%edx) # mapping 0x80000000 => 0x00000000
133
134 leal page_directory, %eax
135 movl %eax, %cr3
136
137 # turn paging on
138 movl %cr0, %ebx
139 orl $(1<<31), %ebx
140 movl %ebx, %cr0
141 ret
142
143
144.section K_DATA_START
145
146.align 4096
147page_directory:
148 .space 4096, 0
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