+# NOTE:
+# shimx64.efi.signed ends up as /EFI/BOOT/bootx64.efi inside [grml_cd]/boot/efi.img, and
+# grubx64.efi.signed ends up as /EFI/BOOT/grubx64.efi inside [grml_cd]/boot/efi.img, whereas
+# [grml_cd]/boot/efi.img is used as `boot/efi.img` inside `xorriso -as mkisofs [...] -e boot/efi.img -no-emul-boot [...]` ISO generation [inside grml_cd directory]