di-netboot-assistant 0.51 (s390x binary) in ubuntu bionic

 di-netboot-assistant is a tool to simplify the preparation of files
 for TFTP net booting. It downloads and extracts the files needed and
 takes care of organizing them. In addition, it prepares a top level
 menu for PXElinux and grub-efi, which allows one to choose from all
 installed netboot images at boot time.
 .
 di-netboot-assistant supports preseeding the installer in order to
 set up systems completely automatically.
 .
 To build EFI boot images, install grub-efi-amd64-bin.