This is good for an entirely different reason, which is running cross-compiled tests in an emulator. That is especially good for bare metal. If you don't have

This is good for an entirely different reason, which is running cross-compiled tests in an emulator. That is especially good for bare metal. If you don't have global allocator, have limitted ram, etc., you might not be able to write the test harness as part of the guest program at all! so you want want to move as much logic to the host program as possible, and then run as little as a few instructions (!) in the guess program. See https://github.com/gz/rust-x86 https://github.com/gz/rust-x86 for an example of doing some of this.