UEFI EDK2 firmware for bhyve with CSM (16-bit BIOS) support.

From https://github.com/tianocore/tianocore/wiki/UEFI :
"The Unified Extensible Firmware Interface, or UEFI, specifies the
firmware layer between an operating system and platform hardware. UEFI
replaces the legacy Basic Input Output System (BIOS)."

EDK2 is the project from TianoCore (https://tianocore.org) that provides
"a modern, feature-rich, cross-platform development environment for the
UEFI and UEFI Platform Initialization (PI) specifications."

It's open source under the BSD-2-Clause-Patent license.

This port provides an EDK2 firmware build for x86_64 with 'CSM' support.
CSM is the Compatibility Support Module, compatibility code to allow
operating systems which expect a 16-bit BIOS, and which don't know
about UEFI, to boot.

This CSM port provides an older version of EDK2 for use with VMs
running operating systems which don't have UEFI support.

WWW: https://github.com/freebsd/uefi-edk2/tree/bhyve/UDK2014.SP1