I did additional testing, and I can confirm that adding "rmmod tpm" does indeed work...
See comment number 51 by Alkis (https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1851311/comments/51). - - - - - - - - - - - - - - - - - - - - - - - - - - - - menuentry "Install" { set isofile="/ubuntu.iso" rmmod tpm loopback loop (hd0,2)$isofile linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile noprompt noeject initrd (loop)/casper/initrd } - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Busy Box error I had experienced was actually due to a bad ISO file. I tested "rmmod tpm" on a system running Ubuntu 19.10. I tested two official Ubuntu *.iso files: - Ubuntu 18.04 - Ubuntu 20.04 In both cases, the system successfully booted the specified *.iso. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1851311 Title: loopback command hangs in 2.04 under UEFI To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1851311/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
