message: increase the readability, remove compiler warnings
diff: @@ -39,7 +39,7 @@ const UHYVE_PORT_NETINFO: u16 = 0x600;
  const UHYVE_PORT_NETWRITE: u16 = 0x640;
  const UHYVE_PORT_NETREAD: u16 = 0x680;
  //const UHYVE_PORT_NETSTAT: u16 = 0x700;
  -const UHYVE_MSG_SIZE: usize = 1792;
  +const UHYVE_MAX_MSG_SIZE: usize = 1792;
  /// Data type to determine the mac address
  #[derive(Debug, Default)]
  @@ -111,7 +111,7 @@ impl UhyveWrite {
  }
  extern "C" fn uhyve_thread(_arg: usize) {
  - info!("Hello form network thread!");
  + debug!("Hello from network thread!");
  let info: UhyveNetinfo = UhyveNetinfo::default();
  @@ -227,7 +227,7 @@ impl<'a> Device<'a> for UhyveNet {
  fn receive(&'a mut self) -> Option<(Self::RxToken, Self::TxToken)> {
  let mut rx = RxToken::new();
  - let data = UhyveRead::new(virt_to_phys(rx.buffer.as_mut_ptr() as usize), UHYVE_MSG_SIZE);
  + let data = UhyveRead::new(virt_to_phys(rx.buffer.as_mut_ptr() as usize), UHYVE_MAX_MSG_SIZE);
  unsafe {
  outl(UHYVE_PORT_NETREAD, virt_to_phys(&data as *const _ as usize) as u32);
  }
  @@ -235,6 +235,7 @@ impl<'a> Device<'a> for UhyveNet {
  if data.ret() == 0 {
  let tx = TxToken { };
  rx.resize(data.len());
  + trace!("resize message to {} bytes", rx.len());
  Some((rx, tx))
  } else {
  @@ -243,27 +244,27 @@ impl<'a> Device<'a> for UhyveNet {
  }
  fn transmit(&'a mut self) -> Option<Self::TxToken> {
  - info!("transmit");
  + trace!("create TxToken to transfer data");
  Some(TxToken {})
  }
  }
  #[doc(hidden)]
  pub struct RxToken {
  - buffer: [u8; UHYVE_MSG_SIZE],
  + buffer: [u8; UHYVE_MAX_MSG_SIZE],
  len: usize
  }
  impl RxToken {
  pub fn new() -> RxToken {
  RxToken {
  - buffer: [0; UHYVE_MSG_SIZE],
  - len: UHYVE_MSG_SIZE
  + buffer: [0; UHYVE_MAX_MSG_SIZE],
  + len: UHYVE_MAX_MSG_SIZE
  }
  }
  pub fn resize(&mut self, len: usize) {
  - if len <= UHYVE_MSG_SIZE {
  + if len <= UHYVE_MAX_MSG_SIZE {
  self.len = len;
  } else {
  warn!("Invalid message size {}", len);
  