Hello,
Foreman Bootdisk plugin at the moment only works in BIOS. To recap, “full” bootdisk utilizes SYSLINUX to directly load kernel and “generic” types use iPXE to chainload from an associated iPXE template.
I am currently working on adding EFI partition so the “full” bootdisk would load on EFI systems too. It will contain grub2 to load the kernel. There were some previous patches that did not get into the upstream, so I am going to resurrect these.
For “generic” host disks, grub2 should be directly load kernel from HTTP via “UEFI HTTP” boot that is part of the spec. I am going to research that. This would make bootdisk UEFI “compatible”, except it would probably not work for TFTP UEFI I am not sure.