1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
/*
* i386 boot code, based on qemu-bmibug.
*
* Copyright 2019 Doug Gale
* Copyright 2019 Linaro
*
* This work is licensed under the terms of the GNU GPL, version 3 or later.
* See the COPYING file in the top-level directory.
*
* SPDX-License-Identifier: GPL-3.0-or-later
*/
.section .head
/* Multi-boot header */
multiboot_st:
.int 0x1BADB002
.int 0x10000
.int -(0x10000+0x1BADB002)
// Load address
.int __load_st
.int __load_st
.int __load_en
.int __bss_en
.int _start
// mode
.int 0
// width
.int 0
// height
.int 0
// depth
.int 0
.code32
.section .text
/* Kernel Entry Point */
.global _start
_start:
// Setup stack ASAP
mov $stack_end,%esp
// Load GDT ASAP
lgdt gdtr
ljmp $0x8,$.Lloadcs
.Lloadcs:
mov $0x10,%eax
mov %eax,%ds
mov %eax,%es
mov %eax,%fs
mov %eax,%gs
mov %eax,%ss
// Fixup the IDT to the ridiculous i386 layout
xor %ebx,%ebx
.Lnextidt:
mov idt_00(,%ebx,8),%eax
shr $16,%eax
movw $0x8,idt_00+2(,%ebx,8)
movw $0x8E00,idt_00+4(,%ebx,8)
movw %ax,idt_00+6(,%ebx,8)
add $1,%ebx
cmp $32,%ebx
jl .Lnextidt
// Load IDTR
push $idt_00
push $((32 * 8 - 1) << 16)
lidt 2(%esp)
add $8,%esp
/*
* Don't worry about stack frame, assume everthing
* is garbage when we return, we won't need it.
*/
call main
/* output any non-zero result in eax to isa-debug-exit device */
test %al, %al
jz 1f
out %ax, $0xf4
1: /* QEMU ACPI poweroff */
mov $0x604,%edx
mov $0x2000,%eax
out %ax,%dx
hlt
jmp 1b
/*
* Helper Functions
*/
/* Output a single character to serial port */
.global __sys_outc
__sys_outc:
pushl %ebp
movl %esp, %ebp
out %al,$0xE9
movl %ebp, %esp
popl %ebp
ret
/* Interrupt Descriptor Table */
.section .data
.align 16
idt_00: .int 0, 0
idt_01: .int 0, 0
idt_02: .int 0, 0
idt_03: .int 0, 0
idt_04: .int 0, 0
idt_05: .int 0, 0
idt_06: .int 0, 0 /* intr_6_opcode, Invalid Opcode */
idt_07: .int 0, 0
idt_08: .int 0, 0
idt_09: .int 0, 0
idt_0A: .int 0, 0
idt_0B: .int 0, 0
idt_0C: .int 0, 0
idt_0D: .int 0, 0
idt_0E: .int 0, 0
idt_0F: .int 0, 0
idt_10: .int 0, 0
idt_11: .int 0, 0
idt_12: .int 0, 0
idt_13: .int 0, 0
idt_14: .int 0, 0
idt_15: .int 0, 0
idt_16: .int 0, 0
idt_17: .int 0, 0
idt_18: .int 0, 0
idt_19: .int 0, 0
idt_1A: .int 0, 0
idt_1B: .int 0, 0
idt_1C: .int 0, 0
idt_1D: .int 0, 0
idt_1E: .int 0, 0
idt_1F: .int 0, 0
gdt:
.short 0
gdtr:
.short gdt_en - gdt - 1
.int gdt
// Code
.short 0xFFFF
.short 0
.byte 0
.byte 0x9b
.byte 0xCF
.byte 0
// Data
.short 0xFFFF
.short 0
.byte 0
.byte 0x93
.byte 0xCF
.byte 0
gdt_en:
.section .bss
.align 16
stack: .space 65536
stack_end:
|
