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[bits 16]
[extern _kernel_size]
[extern _bootloader_stage1_size]
[extern _kernel_loc]
jmp stage0
times 3-($-$$) db 0x90 ; a temporary dirty fix to emulate a floppy disk insted of a hard risk
times 59 db 0 ; (TODO support hard disks)
stage0:
jmp 0:.entry
.entry:
mov ax, 0
mov ds, ax
mov bp, ax
mov ds, ax
mov es, ax
mov ax, 0x8fc0
mov ss, ax
mov ax, 0xfffe
mov sp, ax
mov al, 0x92
or al, 2
out 0x92, al
mov [.boot_device], dl
mov bx, .loadstage2_msg
mov cx, 0
call bios_print
; TODO put in an error message and a maximum fail count
.load_stage1:
mov al, _bootloader_stage1_size
mov cl, 0x2 ; read sector 2
mov dx, 0x0 ; dest segment 0
mov bx, 0x7e00 ; dest offst 0
call bios_disk.load_sectors
jmp mbr_end.entry
.boot_device: db 0
.loadstage2_msg: db "Loading (stage 2) bootloader...", 0
%include "bootloader/bios_functions/bios_disk.asm"
%include "bootloader/bios_functions/print.asm"
times 510 - ($-$$) db 0
dw 0xaa55
%include "bootloader/gdt.asm"
boot_msg:
.kernel_loaded: db `Kernel loaded!\r\nBooting to protected, then long mode...`, 0
.stage2_loaded: db `Done loading bootloader!\r\nLoading kernel...`, 0
mbr_end:
.entry:
; entering unreal mode
mov bx, boot_msg.stage2_loaded
mov cx, 0
call bios_print
cli
push ds
lgdt [protected_gdt.descriptor]
mov eax, cr0
or al, 1
mov cr0, eax
jmp $+2
mov bx, 0x10 ; descriptor 2, the data descriptor
mov ds, bx ; put it into the segment register
mov es, bx ;
and al, 0xfe
mov cr0, eax
pop ds
sti
;we are now in unreal mode
mov cl, 5
mov edi, _kernel_loc
.loop:
mov al, 0x1 ; sector count
mov dx, 0x0 ; dest addr segment
mov bx, 0x500 ; dest addr offset
call bios_disk.load_sectors
inc cl
push cx
mov esi, 0x500
mov ecx, 512
a32 rep movsb
nop
pop cx
cmp cl, _kernel_size+2
je .loop_end
jmp .loop
.loop_end:
mov bx, boot_msg.kernel_loaded
mov cx, 0
call bios_print
call detect_arch
call vbe_init
done:
call enter_longmode
jmp $
%include "bootloader/cpu_check.asm"
%include "bootloader/video.asm"
%include "bootloader/enter_kernel.asm"
times 2048 - ($ - $$) db 0
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