boot.S

# set magic number to 0x1BADB002 to identified by bootloader   
.set MAGIC,    0x1BADB002  
  
# set flags to 0  
.set FLAGS,    0  
  
# set the checksum  
.set CHECKSUM, -(MAGIC + FLAGS)  
  
# set multiboot enabled  
.section .multiboot  
  
# define type to long for each data defined as above  
.long MAGIC  
.long FLAGS  
.long CHECKSUM  
  
  
# set the stack bottom   
stackBottom:  
  
# define the maximum size of stack to 512 bytes  
.skip 512  
  
  
# set the stack top which grows from higher to lower  
stackTop:  
  
.section .text  
.global _start  
.type _start, @function  
  
  
_start:  
  
  # assign current stack pointer location to stackTop  
    mov $stackTop, %esp  
  
  # call the kernel main source  
    call KERNEL_MAIN  
  
    cli  
  
  
# put system in infinite loop  
hltLoop:  
  
    hlt  
    jmp hltLoop  
  
.size _start, . - _start