OS - thread_create

tid_t thread_create(const char *name, int priority,
                    thread_func *function, void *aux)
{
  struct thread *t;
  struct kernel_thread_frame *kf;
  struct switch_entry_frame *ef;
  struct switch_threads_frame *sf;
  tid_t tid;

  ASSERT(function != NULL);

  /* Allocate thread. */
  t = palloc_get_page(PAL_ZERO);
  if (t == NULL)
    return TID_ERROR;

  /* Initialize thread. */

  init_thread(t, name, priority);
  tid = t->tid = allocate_tid();
  t->parent = thread_current();
  enum intr_level old_level = intr_disable();

  child_str *cs = palloc_get_page(0);
  cs->wait_stat = 0;
  cs->t = t;
  cs->tid = tid;
  cs->waited = 0;
  list_push_back(&thread_current()->child_list, &cs->child_elem);

  intr_set_level(old_level);

  t->cwd = NULL;
  if (thread_current()->cwd)
    t->cwd = dir_reopen(thread_current()->cwd);

  /* Stack frame for kernel_thread(). */
  kf = alloc_frame(t, sizeof *kf);
  kf->eip = NULL;
  kf->function = function;
  kf->aux = aux;

  /* Stack frame for switch_entry(). */
  ef = alloc_frame(t, sizeof *ef);
  ef->eip = (void (*)(void))kernel_thread;

  /* Stack frame for switch_threads(). */
  sf = alloc_frame(t, sizeof *sf);
  sf->eip = switch_entry;
  sf->ebp = 0;

  /* Add to run queue. */
  thread_unblock(t);

  return tid;
}