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%define ALIGN 1 ; Align loaded modules on page boundaries
%define MEMINFO 2 ; Provide memory map
%define FLAGS 3 ; Flags (ALIGN | MEMINFO)
%define MAGIC 0x1BADB002
%define CHECKSUM -(MAGIC + FLAGS)
section .multiboot
align 4
dd MAGIC
dd FLAGS
dd CHECKSUM
section .start_section
dd _start
; Initialize stack
section .bss
align 16
global STACK_BOTTOM
global STACK_TOP
STACK_BOTTOM:
resb 0x4000
STACK_TOP:
section .text
global _start
extern kernel_main
_start:
mov esp, STACK_TOP
push ebx
push eax
cli
call kernel_main
cli
jmp $
global jump_userspace
jump_userspace:
cli
push ebp
mov ebp, esp
mov edx, dword [esp + 0xC]
mov esp, edx
push 0xABCDEF
mov ax, 0x23
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov eax, esp
push 0x23
push eax
pushf
; Enable interrupts
pop eax
or eax, 0x200
push eax
push 0x1B
push dword [ebp + 8]
iret
pop ebp
ret
section .end_section
global ASM_KERNEL_END
ASM_KERNEL_END:
; Kernel size detection
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