In order to fulfill the same role as tboot, GRUB had to learn how to prepare the platform and perform the TXT launch. Most of the work for that particular part has been done by Oracle Team working on TrenchBoot for GRUB (www.mail-archive.com/grub-de…167.html). That work, however, covered the Linux kernel TXT launch only. What still had to be done was the Multiboot2 protocol support in GRUB to be able to TXT launch a Xen Hypervisor. The patches have been prepared for the respective Qubes GRUB package (https://github.com/3mdeb/qubes-grub2/pull/2). Xen modifications