Q. What firmware is used with a Generation 2 Hyper-V VM?
A. Windows Server 2012 R2 introduced the Generation 2 VM which is UEFI based instead of BIOS based (Generation 1). With Generation 2 new capabilities like Secure Boot, Shielded VMs and many other features are available and removes the emulated hardware required for legacy operating systems. The actual firmware used is not publically available however its based on Tianocore which has a Github repository at https://github.com/tianocore.