libefi

libefi is a safe, idiomatic Rust implementation of the Unified Extensible Firmware Interface, making it possible to write low-level EFI applications using purely Rust code. It also provides target specifications that can be used to build EFI images directly with Xargo.

Overview

UEFI is the modern replacement for PC BIOS systems. It specifies a standard interface that platform firmware must honor, so that any software written against the specification is portable to any UEFI platform.

This crate uses Rust's rich FFI support to implement types and functions for interacting with UEFI firmware. Most of the structures, functions, and types described in the UEFI specification are implemented purely in Rust, and on top of these are a set of functions for interacting using idiomatic Rust code. This layered approach is used throughout the library, resulting in an API that is ergonomic wherever possible but still incredibly flexible when necessary.

See https://github.com/rust-osdev/uefi-rs for a more general wrapper.

Rust

A nightly compiler is required, as is the Rust source.

1. Install Rust via rustup
2. Add the Rust source component: rustup component add rust-src
3. Switch to the nightly compiler: cd path/to/libefi && rustup override set nightly

Building

See x86_64-unknown-efi target for creating a EFI image.

Running

To run an .efi executable on a real computer:

• Find a USB drive which is FAT12 / FAT16 / FAT32 formatted
• Copy the file to the USB drive, to /EFI/Boot/Bootx64.efi
• In the UEFI BIOS, choose "Boot from USB" or similar

Examples

See the src/bin/test.rs file for an example of an EFI application that uses this crate. See also the Makefile, which demonstrates how to test using qemu and OVMF. When running on Ubuntu, the Makefile has the following package dependencies:

• build-essential
• mtools
• ovmf
• qemu-system-x86
• xorriso