Streamlining secure boot for 26.10

Ubuntu systems support secure boot using grub. grub contains a lot of parsers for file systems and other things which are a constant source of security issues. In 26.10, we’d like to propose removing the following features from signed GRUB builds: Filesystems Remove btrfs, hfsplus, xfs, zfs Retain ext4, fat, iso9660 (and squashfs for snaps) Image formats: Remove jpeg, png Retain none We do not use images, but using that in your grub.cfg locally is a massive security risk (if even still al...