static void
start_process (void *file_name_)
{

  lock_acquire(&process_load_lock);

  char *file_name = file_name_;
  struct intr_frame if_;
  bool success;
  int nrOfArgs = -1;

  /* Initialize interrupt frame and load executable. */
  memset (&if_, 0, sizeof if_);
  if_.gs = if_.fs = if_.es = if_.ds = if_.ss = SEL_UDSEG;
  if_.cs = SEL_UCSEG;
  if_.eflags = FLAG_IF | FLAG_MBS;



  char *token, *save_ptr;
  int  i = 0;
  for (i=0,token = strtok_r (file_name, " ", &save_ptr);i<MAX_NR_ARGS && token != NULL; i++, token = strtok_r (NULL, " ", &save_ptr))
  {
	  argv_global[i] = token;
  }
  nrOfArgs = i;
  success = load (file_name, &if_.eip, &if_.esp);

  if(success)
  {
	  int tokenSize = 0;

	  for(i= nrOfArgs-1 ; i>=0; i-- )
	  {
		  tokenSize = strlen( argv_global[i] );
		  if_.esp = if_.esp - (tokenSize+1);
		  strlcpy((char*)(if_.esp), argv_global[i], PGSIZE);
		  argv_global[i] = (char*)(if_.esp);

		  //printf("start address of array %i = %x\n",i,(int)(argv_global[i]));
	  }

	  int stackAddr = (int)(if_.esp);

	  /* the only solution we found to word align the code ROUND_DOWN does not work , \
	   *  probably because of some compiler optimization*/
	  while(stackAddr%4 != 0)
	  {
		  stackAddr--;
		  *((char*)stackAddr) = 0;
	  }
	  if_.esp = (void*)stackAddr;

	  if_.esp = if_.esp - 4;
	  *((int*)if_.esp) = 0;

	  for(i= nrOfArgs-1 ; i>=0; i-- )
	  {
		  if_.esp = if_.esp - 4;
		  *((int*)if_.esp)= (int)argv_global[i];
	  }
	  //we save the address of argv
	  stackAddr = (int)if_.esp;
	  //we put argv on the stack
	  if_.esp = if_.esp - 4;
	  *((int*)if_.esp) = stackAddr;

	  //we put argc on the stack
	  if_.esp = if_.esp - 4;
	  *((int*)if_.esp) = nrOfArgs;

	  //we put the return address on the stack
	  if_.esp = if_.esp - 4;
	  *((int*)if_.esp) = 0;
  }
  for(i =0 ; i< MAX_NR_ARGS; i++ )
  		  argv_global[i] = NULL;

  lock_release(&process_load_lock);

  /* If load failed, quit. */
  palloc_free_page (file_name);

  thread_current()->statusForParent->loaded = success;
  sema_up(&thread_current()->statusForParent->sem);
  if (!success)
    thread_exit ();

  /* Start the user process by simulating a return from an
     interrupt, implemented by intr_exit (in
     threads/intr-stubs.S).  Because intr_exit takes all of its
     arguments on the stack in the form of a `struct intr_frame',
     we just point the stack pointer (%esp) to our stack frame
     and jump to it. */
  asm volatile ("movl %0, %%esp; jmp intr_exit" : : "g" (&if_) : "memory");
  NOT_REACHED ();
}