66 lines
1.1 KiB
NASM
66 lines
1.1 KiB
NASM
[BITS 32]
|
|
global start
|
|
start:
|
|
mov esp, _sys_stack
|
|
jmp stublet
|
|
|
|
ALIGN 4
|
|
mboot:
|
|
MULTIBOOT_PAGE_ALIGN equ 1<<0
|
|
MULTIBOOT_MEMORY_INFO equ 1<<1
|
|
MULTIBOOT_AOUT_KLUDGE equ 1<<16
|
|
MULTIBOOT_HEADER_MAGIC equ 0x1BADB002
|
|
MULTIBOOT_HEADER_FLAGS equ MULTIBOOT_PAGE_ALIGN | MULTIBOOT_MEMORY_INFO | MULTIBOOT_AOUT_KLUDGE
|
|
MULTIBOOT_CHECKSUM equ -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)
|
|
EXTERN code, bss, end
|
|
; GRUB Multiboot header, boot signature
|
|
dd MULTIBOOT_HEADER_MAGIC
|
|
dd MULTIBOOT_HEADER_FLAGS
|
|
dd MULTIBOOT_CHECKSUM
|
|
; AOUT kludge (must be physical addresses)
|
|
; Linker script fills these in
|
|
dd mboot
|
|
dd code
|
|
dd bss
|
|
dd end
|
|
dd start
|
|
|
|
; Main entrypoint
|
|
stublet:
|
|
extern main
|
|
call main
|
|
jmp $
|
|
|
|
; Global Descriptor Table
|
|
global gdt_flush
|
|
extern gp
|
|
gdt_flush:
|
|
lgdt [gp]
|
|
mov ax, 0x10
|
|
mov ds, ax
|
|
mov es, ax
|
|
mov fs, ax
|
|
mov gs, ax
|
|
mov ss, ax
|
|
jmp 0x08:flush2
|
|
flush2:
|
|
ret
|
|
|
|
; Interrupt Descriptor Table
|
|
global idt_load
|
|
extern idtp
|
|
idt_load:
|
|
lidt [idtp]
|
|
ret
|
|
|
|
; Interrupt Service Routines
|
|
|
|
|
|
; BSS Section
|
|
SECTION .bss
|
|
resb 8192 ; 8KB of memory reserved
|
|
_sys_stack:
|
|
; This line intentionally left blank
|
|
|
|
|