kernel: add definitions for a TTY device interface.

include/socks/console.h

@@ -1,11 +1,27 @@
 #ifndef SOCKS_CONSOLE_H_
 #define SOCKS_CONSOLE_H_
 
+/* The console system
+
+   Consoles are like simplified TTYs. Their purpose is to serve as an output
+   sink for messages printed using printk.
+
+   a console_t could be used to represent a serial port, UART port, or even
+   a text-based framebuffer display. Anything where the job of displaying
+   or sending text can be abstracted to a simple write() call.
+
+   A secondary purpose of consoles is to allow input. For example, a console
+   representing a serial port may allow both sending AND receiving over the
+   port.
+*/
 #include <socks/queue.h>
 #include <socks/locks.h>
 #include <socks/status.h>
 
 typedef enum console_flags {
+	/* console is only used during the boot process. the console
+	   will be automatically de-registered when the first
+	   non-boot console is registered */
 	CON_BOOT = 0x01u,
 } console_flags_t;