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105 | bits 16:
section .boot;
global boot;
%define NULL_SEG 0
%define CODE_SEG 0x8
%define DATA_SEG 0x10
%define RCODE_SEG 0x18
%define RDATA_SEG 0x20
boot:
mov ah, 0x00; Function: Set video mode
mov al, 0x03; Mode: 80x25 text mode (mode 3 dzeb)
int 0x10; Call BIOS interrupt
call load_step1_5; loading the second step from the second sector
call load_gdt;
; pivoting to protected_mode
cli;
mov eax, cr0;
or eax, 1;
mov cr0, eax;
mov ax, DATA_SEG
jmp CODE_SEG:kload;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; GDT ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
gdt_data:
dd 0
dd 0
;gdt_code:
dw 0xFFFF
dw 0
db 0
db 10011010b
db 11001111b
db 0
;gdt_data:
dw 0xFFFF
dw 0
db 0
db 10010010b
db 11001111b
db 0
; rmode gdt
; gdt code
dw 0xFFFF
dw 0
db 0
db 0x9e
db 0
db 0
; gdt data:
dw 0xFFFF
dw 0
db 0
db 0x92
db 0
db 0
gdt_end:
gdt_ptr:
dw gdt_end - gdt_data - 1;
dd gdt_data
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
load_step1_5:
mov ah, 0x2;
mov al, 0x3; we just wanna read 2 sectors for now
mov cl, 0x2;
mov bx, 0x7e00;
int 0x13;
ret;
load_gdt:
cli;
pusha;
lgdt [gdt_ptr];
sti;
popa;
ret;
bits 32
kload:
mov ds, ax
mov ss, ax
mov es, ax
mov esp,kernel_stack_top;
pusha
extern main
call main
popa
jmp -2;
times 510 - ($-$$) db 0
dw 0xaa55
section .bss
align 4
kernel_stack_bottom: equ $
resb 16384 ; 16 KB
kernel_stack_top:
|
