AGESA is updated every few months and a number of motherboard vendors track those changes with BIOS updates. The updates can often contain pretty substantial ch

AGESA is updated every few months and a number of motherboard vendors track those changes with BIOS updates. The updates can often contain pretty substantial changes, like resizable BAR support. Further: I'm typing this on a Macbook Pro which is running right now only because I was able to pull the bootrom (which is UEFI), add a NVME driver from a newer Macbook Pro, package it back up, and flash it back to the older Macbook Pro. This let me use an NVME drive in a machine released before they added NVME support to that system's bootrom. The only side effect was that the OS didn't fully support NVME standby modes so power consumption was slightly higher, but even that was fixed in a later OS update which was released after NVME drives were in several models.