61 pushl %ebp  // new_stack[new_esp--] <- ebp
62
63   movl %esp,%ebp  // FP -> Caller's SP
64  addl $12,%ebp  // FP -> FP slot
 
66  call *%eax  // branch to RVM
in the line of 64, why add 12 to ebp,? I changed 12 to 16, it seemed that there's no error, RVM can run programm yet.