Side note : when using efisys.bin (which happens to be a floppy), EmulationNone works fine.
I am confused now : should not it be Emulation144MFloppy?
No, not really.
The "normal" or "intended" behaviour of the El-Torito floppy emulation was that of floppy emulation
The result is similar to having a dual LUN device.
The floppy disk is a "separate" device that gets its own drive letter and - for all the BIOS knows - is a (read only) bootable floppy drive.
As a matter of fact it is the simplest possible booting method, the (emulated) floppy is mounted/accessed as "first floppy" (please read as (fd0) or drive #0 or A: if you prefer) and its bootsector is chainloaded by the BIOS just as if it was a "normal" floppy.
For some time it was the only available method to boot CD's (I am talking here of DOS and NT 3.5/early 4.0 times) as many BIOSes were not compatible with the "no-emulation" mode that MS adopted for non-DOS botable CD's.
In the good ol' times the NT 4.0 install CD was not even bootable and it came (from MS) with three floppies, you booted from the first floppy, read the other two and only then you would start accessing (hopefully) the CD.
Moreover at the time the access to *any* device was - at least as BIOS level - in CHS (and not LBA) mode, so the geometry was important and BIOSes has already suitable CHS code for floppies formats.
As mentioned on the given thread, and here:http://reboot.pro/to...brided/?p=86679
the good guys at MenuetOS took this concept a step further, putting together the simpler possible way to create a bootabloe .iso, that is ONLY a bootable emulated floppy (with no CDFS or UDF filesystem attached).
The efisys.bin, that the good MS guys arbitrarily decided to make with the same size as a floppy disk is instead intended for UEFI/EFI only, and it behaves as a "searchable filesystem", there is no reason why it should be this or that size or have this or that geometry.
The UEFI "sees" a filesystem and looks in it for either BOOTX64.EFI or a BOOTIA32.EFI (hardcoded names for UEFI bootfiles).
About superfloppies, it will cost you nothing to add them.
The point is that El-Torito allows for three types of floppies, the details are here, JFYI:http://www.msfn.org/...&comment=972183
0x1=1200 K i.e. 80/2/15
0x2=1440 K i.e. 80/2/18
0x3=2880 K i.e. 80/2/36
That were actually implemented in all BIOS tested as:
the issue is that most iso making tools (where the programmers have been either as royalist as or more royalist than the king) do check the actual size of the file provided for "floppy emulation" and, if it doesn't correspond to the "standard" size, throws an error.
So, if your tool allows *any* size of the file for "Bootfile", it already works just fine for superfloppies, if there is a check for sizes, then either removing it altogether or offering an option to remove it would be enough.
As a side note:
Boot File (X86)
should really be either of:
Boot File (El-Torito)
or (IMHO better)
Boot File (BIOS)
If you prefer, a UEFI machine with CSM (please read BIOS) enabled should boot out of that file even if the contents are X64 (or whatever).