And sometimes impossible
In Python/Ruby sure, it's easy. In Java, or even C++, it's doable, but not great, and it requires some heavy tricks.
But they surely need tests, but not necessarily TDD.
This is what I expect from an OS developers
Maybe the people from OpenSSL have some test like that already
I've been in that position. Sometimes with embedded, you can't have software fixtures, only hardware ones. (Bit banging)
And you think you know what the device answers and understands, but there's usually some gotchas.
And sometimes impossible
In Python/Ruby sure, it's easy. In Java, or even C++, it's doable, but not great, and it requires some heavy tricks.
But they surely need tests, but not necessarily TDD.