The Unified Extensible Firmware Interface (UEFI) is a specification that defines a software interface between an operating system and platform firmware. UEFI replaces the legacy Basic Input/Output System (BIOS) firmware interface originally present in all IBM PC-compatible personal computers,with most UEFI firmware implementations providing support for legacy BIOS services. UEFI can support remote diagnostics and repair of computers, even with no operating system installed.
Advantages :
The interface defined by the EFI specification includes data tables that contain platform information, and boot and runtime services that are available to the OS loader and OS. UEFI firmware provides several technical advantages over a traditional BIOS system:
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Ability to use large disks partitions (over 2 TB) with a GUID Partition Table (GPT)
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CPU-independent architecture
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CPU-independent drivers
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Flexible pre-OS environment, including network capability
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Modular design
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Backward and forward compatibility
To know more about UEFI refer to this official UEFI site:
Unified Extensible Firmware Interface (UEFI) Forum
In Nutanix for example after you launch a VM console from the Prism web console UI, the UEFI firmware menu allows you to do the following tasks for the VM.
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Changing default boot resolution
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Setting up boot device
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Changing boot-time value
See more details in this document: Getting Familiar WithUEFI Firmware Menu
Note: Nutanix provides UEFI support starting from AOS 5.11
If you need to Know How to migrate UEFI VMs from ESXi to AHV, read this article: How to migrate UEFI VMs from ESXi to AHV