console: Create a console abstraction

[d4ilyrun]

Issue

The way we log currently is we hardcoded the logger to output through the UART so we can read it in color from qemu's console.

This, although working for now, has the downside of not being versatile. What if we want to print some information to the uart and some onto the user's screen? What if we want to print onto both at the same time? What if we want to print it into a file?

Solution

We could create a console structure, containing the necessary information to interact with a console.

This includes:

• write
• putc
• close
• open/init

We would initialize the logger with the apporpriate struct, and just have it forward the actual hardware interaction to underlying "driver" (uart, terminal, file?, ...).

[d4ilyrun]

After seeing more example implementations, this is usually generalized through the VFS.
The console should be nothing more than an open file descriptor to the underlying driver (be it UART or FB, or even a regular file).

I think I'll be using this as a POC for my VFS when adding support for it (which is the next thing I'm planning to work on).

Prerequisites

• Implement VFS
• Add device API
• Add devtmpfs