Hi, i created an ISO with this partition table:
$ /sbin/gdisk -l test.iso ... MBR: protective ... GPT: present ... Number Start (sector) End (sector) Size Code Name 1 64 7713831 3.7 GiB 0700 ISO9660 2 7713832 7714663 416.0 KiB EF00 Appended2 by mnt=/mnt/iso sudo mount firmware-buster-DI-alpha2-amd64-DVD-1.iso "$mnt" xorriso -as mkisofs \ -o test.iso \ -r \ -V 'Debian buster-DI-a2 amd64 1' \ -partition_offset 16 \ -append_partition 2 0xef "$mnt"/boot/grub/efi.img \ -appended_part_as_gpt \ "$mnt" It will not work from DVD and not in BIOS Legacy mode. (On MS-Windows it will not show long file names. I avoided complaints about symlinks by avoiding option -J.) But if started as reported by Rick Thomas: > [...] by doing some command-line stuff in the EFI > firmware — telling it to boot the file “fs0:\efi\boot\bootx64.efi” then there should be a mountable Debian ISO in partition 1. So the initrd stuff should get over the error occasion "Incorrect CD-ROM detected". (I meanwhile expressed my view about the ISO detection code in https://lists.debian.org/debian-cd/2018/06/msg00000.html ) Have a nice day :) Thomas