; ; Kernel stub ; ; ; We are in 32bits protected mode ; [bits 32] ; ; Export entrypoint ; [global kstart] ; ; Import kernel entrypoint ; [extern kmain] ; ; Posible multiboot header flags ; MULTIBOOT_MODULE_ALIGN equ 1<<0 MULTIBOOT_MEMORY_MAP equ 1<<1 MULTIBOOT_GRAPHICS_FIELDS equ 1<<2 MULTIBOOT_ADDRESS_FIELDS equ 1<<16 ; ; Multiboot header defines ; MULTIBOOT_HEADER_MAGIC equ 0x1BADB002 MULTIBOOT_HEADER_FLAGS equ MULTIBOOT_MODULE_ALIGN | MULTIBOOT_MEMORY_MAP MULTIBOOT_HEADER_CHECKSUM equ -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS) ; ; Kernel stack size ; KERNEL_STACKSIZE equ 0x4000 section .text ; ; Multiboot header ; align 4 dd MULTIBOOT_HEADER_MAGIC dd MULTIBOOT_HEADER_FLAGS dd MULTIBOOT_HEADER_CHECKSUM ; ; Entrypoint ; kstart: mov esp, KERNEL_STACK+KERNEL_STACKSIZE ;Create kernel stack push eax ;Multiboot magic number push ebx ;Multiboot info call kmain ;Call kernel entrypoint cli ;Clear interrupts hlt ;Halt machine section .bss ; ; Kernel stack location ; align 32 KERNEL_STACK: resb KERNEL_STACKSIZE