section .multiboot header_start: dd 0xe85250d6 ; magic number dd 0 ; protected mode code dd .end - header_start dd 0x100000000 - (0xe85250d6 + 0 + (.end - header_start)) dw 0 dw 0 dd 8 .end: extern kernelMain KERNEL_STACK_SIZE equ 4096 ; 4kb of stack global _start section .text _start: ; setup stack for kernel main function mov esp, stack + KERNEL_STACK_SIZE lgdt [gdt32.end] ; call main function call 0x08:kernelMain .loop: jmp .loop section .data ALIGN 4 gdt32: dq 0 .code: dw 0xffff dw 0 db 0 db 10011010b db 11001111b db 0 .data: dw 0xffff dw 0 db 0 db 10010010b db 11001111b db 0 .end: dw .end - gdt32 - 1 dd gdt32 section .bss align 4 stack: resb KERNEL_STACK_SIZE