qemu-system-i386 -kernel os.bin

grub-mkrescue -o bootable.iso iso

qemu-system-i386 -cdrom bootable.iso

menuentry "OS" {
multiboot /os.bin
}

ENTRY(_start)


SECTIONS
{
   . = 1M;
   kernel_phys_start = .;

   .text BLOCK(4K) : ALIGN(4K)
   {
      *(.multiboot)
      *(.text)
   }

   .rodata BLOCK(4K) : ALIGN(4K)
   {
      *(.rodata)
   }

   .data BLOCK(4K) : ALIGN(4K)
   {
      *(.rodata)
   }

   .bss BLOCK(4K) : ALIGN(4K)
   {
      *(COMMON)
      *(.bss)
   }
   kernel_phys_end = .;
}

.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 init

   # Hang if kernel_main unexpectedly returns.
   cli
1:   hlt
   jmp 1b
.size _start, . - _start