Add stupid first serial output

src/kernel/io.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <stdint.h>
+
+extern "C" {
+
+/// Read a byte from an IO port.
+/// \arg port  The address of the IO port
+/// \returns   One byte read from the port
+uint8_t inb(uint16_t port);
+
+/// Write a byte to an IO port.
+/// \arg port  The addres of the IO port
+/// \arg val   The byte to write
+void outb(uint16_t port, uint8_t val);
+
+}
+
+const uint16_t COM1 = 0x03f8;