[SeaBIOS](https://www.seabios.org/SeaBIOS) is an implementation of an x86 BIOS which relies on [coreboot](https://www.coreboot.org/). It is used for legacy systems, but also to specialized and cloud optimized guests systems which don't require UEFI.
[OVMF](https://github.com/tianocore/tianocore.github.io/wiki/OVMF), which stands for Open Virtual Machine Firmware, is a UEFI-compatible firmware.
It is based on the [TianoCore](https://www.tianocore.org/) project, which provides an open-source implementation of a platform firmware that follows UEFI specifications.
It is the default method to boot UEFI-based operating systems in a virtual machine.
The [Rust Hypervisor Firmware](https://github.com/cloud-hypervisor/rust-hypervisor-firmware) (RHF) is a UEFI-compatible firmware. It is focused on simplicity and performance and is designed to run cloud-centric operating systems.
