# Declare constants for the multiboot header. .set ALIGN, 1<<0 # align loaded modules on page boundaries .set MEMINFO, 1<<1 # provide memory map .set FLAGS, ALIGN | MEMINFO # this is the Multiboot 'flag' field .set MAGIC, 0x1BADB002 # 'magic number' lets bootloader find the header .set CHECKSUM, -(MAGIC + FLAGS) # checksum of above, to prove we are multiboot # Declare a header as in the Multiboot Standard. .section .multiboot .align 4 .long MAGIC .long FLAGS .long CHECKSUM # Reserve a stack for the initial thread. .section .bss .align 16 stack_bottom: .skip 16384 # 16 KiB stack_top: # The kernel entry point. .section .text .global _start .type _start, @function _start: movl $stack_top, %esp # Call the global constructors. call _init # Transfer control to the main kernel. call kernel_main # Hang if kernel_main unexpectedly returns. cli 1: hlt jmp 1b .size _start, . - _start