INITRD Basics

[GMN]

This turned out to be much simpler than it seemed. The downloaded file appeared not as a RAMdisk (hence, no new fs device) but as just a file in the default volume.
My mistake was thinking that because this was a disk image file, that an INITRD would create a UEFI disk. Nope... just a file.

UEFI FileIo was able to access the file by name. Since what I was looking for was it's address in physical memory, but it was stored as a file, it was just a matter of reading the file size, allocating memory for it, and reading the file into the allocated memory. Pass the address and size through to the booting OS and it was able to mount the disk image as a RAMdisk. Problem solved.