Hello Masahisa, The UEFI specification does not require that BootOrder is defined. Instead /EFI/BOOT/BOOT<ARCH>.EFI will be booted if not BootOrder is defined.
Currently tcg2 measurement fails with EFI_NOT_FOUND in this case. Please, correct tcg2_measure_boot_variable() to correctly handle booting without BootOrder. Best regards Heinrich