title: Symbols are not recognize linux driver
body: <p>I try to load a linux driver and I got this message :</p>
  
  <pre><code># modprobe hci_uart
  hci_uart: Unknown symbol hci_free_dev (err 0)
  hci_uart: Unknown symbol hci_alloc_dev (err 0)
  hci_uart: Unknown symbol bt_info (err 0)
  hci_uart: Unknown symbol bt_err (err 0)
  hci_uart: Unknown symbol hci_unregister_dev (err 0)
  hci_uart: Unknown symbol hci_recv_frame (err 0)
  hci_uart: Unknown symbol hci_register_dev (err 0)
  hci_uart: Unknown symbol bt_warn (err 0)
  hci_uart: Unknown symbol hci_free_dev (err 0)
  hci_uart: Unknown symbol hci_alloc_dev (err 0)
  hci_uart: Unknown symbol bt_info (err 0)
  hci_uart: Unknown symbol bt_err (err 0)
  hci_uart: Unknown symbol hci_unregister_dev (err 0)
  hci_uart: Unknown symbol hci_recv_frame (err 0)
  hci_uart: Unknown symbol hci_register_dev (err 0)
  hci_uart: Unknown symbol bt_warn (err 0)
  modprobe: can't load module hci_uart (kernel/drivers/bluetooth/bluetooth_uart_driver/hci_uart.ko): unknown symbol in module, or unknown parameter
  </code></pre>
  
  <p>The module is checked in <code>linux-menuconfig</code> (I use <code>buildroot</code>), I tried to load an other linux driver and I do not get this message.</p>
  
  <p>Any idea.
  Thank you very much.</p>