# declare some constants
.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

# the bootloader will search for this magic sequence
# and recognize us as a multiboot kernel
.section .text  # .multiboot does not work ??
.align 4
.long MAGIC
.long FLAGS
.long CHECKSUM

# allocatable, writable, contains no data
.section .bootstrap_stack, "aw", @nobits
stack_bottom:
.skip 16384         # 16 KiB
stack_top:

# the linker script specifies _start as the entry point to the kernel and the
# bootloader will jump to this position once the kernel has been loaded
.section .text
.global _start
.type _start, @function
_start:
    movl $stack_top, %esp
    push %eax
    push %ebx

    call kernel_main

    cli

hang:
    hlt
    jmp hang

# Set the size of the _start symbol to the current location '.' minus its start.
# This is useful when debugging or when you implement call tracing.
.size _start, . - _start