Documentation

Miralis is a RISC-V firmware that virtualizes RISC-V firmware. We call Miralis a Virtual Firmware Monitor.

Status: Miralis is a research project, and is not fit for production yet.

Motivation

Usually, low level software is granted high privilege. For instance, on RISC-V, platform-specific operations such as cache configuration and power management are handled in M-mode, with full access to all the machine's code and data. This is not a great situation: any bug or vulnerability in the machine's firmware can take down or compromise the whole system.

This can be easily solved by redesigning system firmware, leveraging ideas from the multitude of micro-kernels. Unfortunately, it is hard to convince all hardware vendors to re-design their firmware. Miralis provides an alternative solution by efficiently de-privileging unmodified vendor firmware.

How Does It Work?

On RISC-V, firmware runs in M-mode. Miralis instead runs firmware in U-mode and emulates privileged instructions and memory accesses, creating the illusion of a virtual M-mode (vM-mode). This is a classic virtualization technique also known as trap and emulate.

        ┌──────────────┐ ┌────────────┐
U-mode  │   User App   │ │  Firmware  │ vM-mode
        ├──────────────┤ └────────────┘
S-mode  │    Kernel    │
        ├──────────────┴──────────────┐
M-mode  │           Miralis           │
        └─────────────────────────────┘

Quick Start

To get started, first install the dependencies:

1. Install Rust (see the instructions).
2. Install Just (can be installed with cargo install just).
3. Install qemu-system-riscv64:
   • On Ubuntu: sudo apt install qemu-system-riscv64.
   • On macOS: brew install qemu.

Then, in the Miralis folder:

4. Run just install-toolchain to install the required Rust components.
5. Run just run to run Miralis with a small firmware.

You should see an "Hello, world!".

Now, to run something slightly more interesting, try just run linux-shell. This will download an OpenSBI + Linux image and run it on top of Miralis. Although it looks like a standard Linux environment, the M-mode firmware (OpenSBI) is actually running in user-space!

Going Further

For more details, user guides, and platform support see the documentation. You can also check-out the reproducible artifact from the SOSP'25 paper. If you think Miralis can be useful to you, get in touch! We are always looking for new use-cases.