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
|
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
; THE FOOL-BOOT-LOADER
;
; * X sectors of our kernel loaded at KERNEL_OFFSET from floppy
;
; * memory map made available at MEMMAP_OFFSET
; (check at MEMMEP_SIZE_OFFSET for number of entries)
;
; * the VESA mode specified by VESA_MODE_SELECT will be set up
; (check at VESA_MODES, and VESA_MODE_INFO
; for additional information)
;
; * interrupts disabled
;
; * 32-bit protected mode set up.
;
; * esp set under MBR
;
; * A20 gate opened
;
; * and finally we will jump into the C world to kernel_main() !
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;we want 16-bit instructions, before we switch to 32-bit protected mode.
[bits 16]
;define origin of boot record in memory: 0x7c00
;this is where the BIOS per definition will put the first
;512 bytes of data from the boot device
;The Boot record is identified by the last 2 magic bytes: 0xaa55 (?)
[org 0x7e00]
;;define some constants
;;where we will load our kernel into memory and some
;;other memory locations
;
MEMMAP_SIZE_OFFSET equ 0x7c00
MEMMAP_OFFSET equ 0x7c01
VESA_MODES equ 0x8300
VESA_MODE_INFO equ 0x8400
VESA_MODE_SELECT equ 0x4114
;
jmp boot_16 ;start boot process
;;SOME Global Data, mainly info/error strings
BOOT_DRIVE:
db 0xff
STR_VERSION:
db "Fool Loader Stage 2 v0.5",0
STR_LOAD:
db "Loading Kernel...",0
STR_BOOT:
db "Boot Drive: ",0
MEMMAP_INFO:
db "Getting Memory Map from BIOS.",0
;
;;lets put our temporary GDT (Global Descriptor Table) here
;;kernel should move this away
%include "boot/GDT.asm"
;
;;include 16-bit real mode routines (print_string, disk_load, vesa_setup,check_a20)
%include "boot/disk_load_16.asm"
;%include "boot/check_a20_16.asm"
%include "boot/print_string_16.asm"
%include "boot/vesa_setup_16.asm"
;
;;include our routines for switching to 32-bit protected mode
%include "boot/pm.asm"
;
;
;;get memory map routine
%include "boot/memmap.asm"
;
;;;;;;;;; BOOT 16-bit real ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
;;lets start
[bits 16]
boot_16:
mov [BOOT_DRIVE],dl
; pr info
mov bx, STR_VERSION
call print_string
call print_nextline
mov bx, STR_BOOT
call print_string
mov al,dl
call print_hex_byte
call print_nextline
;show bootdrive
; Load the KERNEL Image
mov bx, STR_LOAD
call print_string
call print_nextline
call disk_load_16
; memmap message
mov bx,MEMMAP_INFO
call print_string
call print_nextline
;get memory map from bios before we enter 32 bit protected mode
mov ax,0 ; set target address in es:di (0:offset)
mov es,ax
mov di,MEMMAP_OFFSET
call BiosGetMemoryMap ; this will also put the number of entries
; of the memory map at MEMMAP_SIZE_OFFSET
call VesaSetup
call switch_to_pm
;
;;;;;;;;; BOOT 32-bit protected mode;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
[bits 32]
boot_32_pm:
;Fast A20 Gate:
;http://wiki.osdev.org/A20_Line
in al, 0x92
or al, 2
out 0x92, al
; call kernel!
mov eax,0 ;tell the kernel
; we are the booting processor
call 0x18000 ;jump into our Kernel!
|
