message: use explicitly x8 to write data to UART1
  simplifies the emulation of UART in uhyve
diff: -use core::ptr;
  -
  pub struct SerialPort {
  - port_address: u32,
  + pub port_address: u32,
  }
  impl SerialPort {
  @@ -17,16 +15,26 @@ impl SerialPort {
  // LF newline characters need to be extended to CRLF over a real serial port.
  if byte == b'\n' {
  unsafe {
  - core::ptr::write_volatile(port, b'\r');
  + asm!(
  + "str x8, [{port}]",
  + port = in(reg) port,
  + in("x8") b'\r',
  + options(nostack),
  + );
  }
  }
  unsafe {
  - core::ptr::write_volatile(port, byte);
  + asm!(
  + "str x8, [{port}]",
  + port = in(reg) port,
  + in("x8") byte,
  + options(nostack),
  + );
  }
  }
  - pub fn init(&self, baudrate: u32) {
  + pub fn init(&self, _baudrate: u32) {
  // We don't do anything here (yet).
  }
  }
  