Use the same file paths in both ISO and FAT
- In the FAT file system, the kernel and all initramfs images are in
/EFI/archiso/. - In the ISO, the kernel and main initramfs are in
/arch/boot/x86_64/, and the microcode images are in/arch/boot/.
Presumably the file placement in FAT is because of UEFI specification (section 13.3.1.3): "All OS loaders and applications will be stored in subdirectories below EFI". Does the kernel qualify for that description (it does have CONFIG_EFI_STUB) or do we even care?
By using the same paths, the same boot loader configuration files could be used for both CD and USB.