Installing Rust

First, you need to get a copy of Rust! There's one catch though: you'll need to get exactly the correct version of Rust. Unfortunately, for OS development, we need to take advantage of some cutting-edge features that aren't yet stable.

Luckily, the Rust project has a tool that makes it easy to switch between Rust versions: rustup. You can get it from the install page of the Rust website.

By default, rustup uses stable Rust. So let's tell it to install nightly:

$ rustup update nightly

This installs the current version of nightly Rust. We run all of the examples in this book under continuous integration, so we should know if something changes in nightly Rust and breaks. But please file bugs if something doesn't work.

Because nightly Rust includes unstable features, you shouldn't use it unless you really need to, which is why rustup allows you to override the default version only when you're in a particular directory. We don't have a directory for our project yet, so let's create one:

$ mkdir intermezzOS
$ cd intermezzOS

A fun way to follow along is to pick a different name for your kernel, and then change it as we go. Call your kernel whatever you want. intermezzOS was almost called ‘Nucleus’, until I found out that there’s already a kernel with that name that’s installed on billions of embedded devices. Whoops!

Inside your project directory, set up the override:

$ rustup override add nightly

Nice and easy. We can't get the version wrong; rustup handles it for us.