The Linux versions I have stayed with in my past, are Kanotix versions. This does not change the fact that they are Debian-based; it only means that the Kanotix Team has simplified the packaging of a specific Debian system, so that it is ready to go.
Kanotix Dragonfire -> Debian / Wheezy (obsolete),
Kanotix Spitfire -> Debian / Jessie (actual).
I have never had to do this. But if we wanted to install Linux on a UEFI-BIOS Motherboard, Kanotix makes it easy. They have a fabled installer called their ‘Acritox Installer’, which allows the user to specify an arbitrary part of the file system, which should be mounted from non-root disk partitions. Typically, this was done with the ‘/home‘ mount-point, using a Linux-oriented file system, such as ‘ext4‘. But for UEFI, we need to tell Acritox, to make custom, FAT32 mount-point at ‘/boot/efi‘ , which therefore has its own partition.
The fact that this needs to be done, implies that this partition, which will either need to be a ‘Primary MBR’ or ‘Any GPT’ partition, will be readable by the BIOS, even before the O/S boots. This is the logical place where the O/S will store the signatures, of all the Images which are supposed to be bootable. Hence, there has been no special change to the format, in which the actual ‘initramfs‘ images are stored, but rather, every time we do an ‘update-initramfs‘, doing so will also add an entry to this FAT32 partition, for the newly-added image.
(Edit 04/05/2016 : ) According to the fact that I have discovered a major error in my thinking, it is also a fact, that this partition does not really store EFI signatures…
Dirk