01-grub.cfg

set default=0
set timeout=10

set gfxmode=auto
insmod efi_gop
insmod efi_uda

menuentry "MyOS" {
    search.fs_label SOMELABEL root
    set gfxpayload=keep
    linux /boot/vmlinuz quiet
    initrd /boot/initrd
}

02-mkimage.sh

grub-mkimage -O x86_64-efi -o EFI/BOOT/BOOTX64.EFI --config=boot/grub/grub.cfg \
    --compression=xz disk part_msdos part_gpt linux loopback normal configfile search \
    search_label true iso9660 efi_uga efi_gop gfxterm gfxmenu gfxterm_menu fat ls cat tar

03-efi-build.sh

dd if=/dev/zero of=efiboot.img bs=4k count=1000
mkfs.vfat efiboot.img
mount efiboot.img /mnt
cp -r EFI/ /mnt
unmount /mnt

04-iso-build.sh

xorriso -as mkisofs -l -J -R -V SOMELABEL \
  -no-emul-boot -boot-load-size 4 -boot-info-table \
  -b boot/isolinux/isolinux.bin -c boot/isolinux/boot.cat \
  -ishybrid-mbr /usr/lib/ISOLINUX/isohdpfx.bin \
  -eltorito-alt-boot -e efiboot.img -no-emul-boot -isohybrid-gpt-basdat \
  -o some_output.iso .