|
|
|
|
[org 0x7c00] ; bootsector
|
|
|
|
|
KERNEL_OFFSET equ 0x1000
|
|
|
|
|
|
|
|
|
|
; Save the boot drive index
|
|
|
|
|
mov [BOOT_DRIVE], dl
|
|
|
|
|
|
|
|
|
|
; Move the stack pointer somewhere safe
|
|
|
|
|
mov bp, 0xe000
|
|
|
|
|
mov sp, bp
|
|
|
|
|
|
|
|
|
|
; BIOS stuff
|
|
|
|
|
call e820 ; map physical memory
|
|
|
|
|
|
|
|
|
|
; Load kernel into memory
|
|
|
|
|
call load_kernel
|
|
|
|
|
|
|
|
|
|
; Switching to PM
|
|
|
|
|
call pm_preinit
|
|
|
|
|
|
|
|
|
|
jmp $ ; inf loop
|
|
|
|
|
|
|
|
|
|
%include "bootloader/equ/ascii.asm"
|
|
|
|
|
%include "bootloader/equ/bios.asm"
|
|
|
|
|
|
|
|
|
|
; BIOS SRs
|
|
|
|
|
%include "bootloader/bios/convert.asm"
|
|
|
|
|
%include "bootloader/bios/print.asm"
|
|
|
|
|
%include "bootloader/bios/disk.asm"
|
|
|
|
|
%include "bootloader/bios/memory.asm"
|
|
|
|
|
|
|
|
|
|
; Protected Mode SRs
|
|
|
|
|
%include "bootloader/equ/vga.asm"
|
|
|
|
|
%include "bootloader/pm/vga/print.asm"
|
|
|
|
|
|
|
|
|
|
; GDT & switching to PM
|
|
|
|
|
%include "bootloader/pm/gdt.asm" ; GDT defined here
|
|
|
|
|
|
|
|
|
|
; Switching to PM
|
|
|
|
|
[bits 16]
|
|
|
|
|
pm_preinit:
|
|
|
|
|
|
|
|
|
|
; PM prep stuff
|
|
|
|
|
cli ; Switch interupts
|
|
|
|
|
lgdt [gdt_descriptor] ; Tell the CPU about the GDT
|
|
|
|
|
mov eax, cr0 ; Set first bit of the CR0 register
|
|
|
|
|
or eax, 0x1 ; to 1
|
|
|
|
|
mov cr0, eax ; Update the control register
|
|
|
|
|
|
|
|
|
|
; Initialize PM
|
|
|
|
|
jmp GDT_CODE_SEG:pm_init
|
|
|
|
|
|
|
|
|
|
[bits 32]
|
|
|
|
|
; Init registers & stack when in PM
|
|
|
|
|
pm_init:
|
|
|
|
|
mov ax, GDT_DATA_SEG ; Point the segment registers to GDT_DATA_SEG
|
|
|
|
|
; Segment registers
|
|
|
|
|
mov ds, ax
|
|
|
|
|
mov ss, ax
|
|
|
|
|
mov es, ax
|
|
|
|
|
mov fs, ax
|
|
|
|
|
mov gs, ax
|
|
|
|
|
|
|
|
|
|
mov ebp, 0xf00000 ; Update the stack pointer
|
|
|
|
|
mov esp, ebp
|
|
|
|
|
|
|
|
|
|
call BEGIN_PM
|
|
|
|
|
|
|
|
|
|
BEGIN_PM:
|
|
|
|
|
; Call the kernel
|
|
|
|
|
call KERNEL_OFFSET
|
|
|
|
|
jmp $
|
|
|
|
|
|
|
|
|
|
[bits 16]
|
|
|
|
|
load_kernel:
|
|
|
|
|
mov bx, KERNEL_OFFSET ; Load kernel at the kernel offset
|
|
|
|
|
mov dh, 14 ; Read sectors
|
|
|
|
|
mov dl, [BOOT_DRIVE] ; Drive index
|
|
|
|
|
call disk_read ; Load the kernel
|
|
|
|
|
|
|
|
|
|
ret
|
|
|
|
|
|
|
|
|
|
BOOT_DRIVE: db 0
|
|
|
|
|
|
|
|
|
|
; Bootsector
|
|
|
|
|
times 510-($-$$) db 0
|
|
|
|
|
dw 0xaa55 ; magic BIOS numbers
|
