You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
52 lines
1.4 KiB
52 lines
1.4 KiB
; Identical to lesson 13's boot sector, but the %included files have new paths
|
|
[org 0x7c00]
|
|
KERNEL_OFFSET equ 0x1000 ; The same one we used when linking the kernel
|
|
|
|
mov [BOOT_DRIVE], dl ; Remember that the BIOS sets us the boot drive in 'dl' on boot
|
|
mov bp, 0x9000
|
|
mov sp, bp
|
|
|
|
mov bx, MSG_REAL_MODE
|
|
call print
|
|
call print_nl
|
|
|
|
call load_kernel ; read the kernel from disk
|
|
call switch_to_pm ; disable interrupts, load GDT, etc. Finally jumps to 'BEGIN_PM'
|
|
jmp $ ; Never executed
|
|
|
|
%include "boot/print.asm"
|
|
%include "boot/print_hex.asm"
|
|
%include "boot/disk.asm"
|
|
%include "boot/gdt.asm"
|
|
%include "boot/32bit_print.asm"
|
|
%include "boot/switch_pm.asm"
|
|
|
|
[bits 16]
|
|
load_kernel:
|
|
mov bx, MSG_LOAD_KERNEL
|
|
call print
|
|
call print_nl
|
|
|
|
mov bx, KERNEL_OFFSET ; Read from disk and store in 0x1000
|
|
mov dh, 16 ; Our future kernel will be larger, make this big
|
|
mov dl, [BOOT_DRIVE]
|
|
call disk_load
|
|
ret
|
|
|
|
[bits 32]
|
|
BEGIN_PM:
|
|
mov ebx, MSG_PROT_MODE
|
|
call print_string_pm
|
|
call KERNEL_OFFSET ; Give control to the kernel
|
|
jmp $ ; Stay here when the kernel returns control to us (if ever)
|
|
|
|
|
|
BOOT_DRIVE db 0 ; It is a good idea to store it in memory because 'dl' may get overwritten
|
|
MSG_REAL_MODE db "Started in 16-bit Real Mode", 0
|
|
MSG_PROT_MODE db "Landed in 32-bit Protected Mode", 0
|
|
MSG_LOAD_KERNEL db "Loading kernel into memory", 0
|
|
|
|
; padding
|
|
times 510 - ($-$$) db 0
|
|
dw 0xaa55
|