The source project of this merge request has been removed.
For secure boot on live system, use gcdx64.efi.signed for amd64 and gcdaa64.efi.signed for arm64
In the file list here: https://packages.ubuntu.com/xenial/amd64/grub-efi-amd64-signed/filelist gcdx64.efi.signed is the boot loader for removable device, like CD or USB flash drive, while grubx64.efi.signed is for hard drive. Therefore for live system, use gcdx64.efi.signed for amd64 and gcdaa64.efi.signed for arm64 in binary_grub-efi. If grubx64.efi.signed is used, the /boot/grub/grub.cfg on the created live CD or USB drive won't be read, and the live system will enter grub shell. This was tested OK when creating a live system about Ubuntu Linux. My 2 cents.