configure_iommu_grub preferred /boot/efi/EFI/*/grub.cfg, but on Fedora that path is a 159-byte stub that chainloads /boot/grub2/grub.cfg. grub2-mkconfig refuses to overwrite it and exits non-zero, and since install.sh runs under set -e the whole installer died there — after the modules were installed but before the final summary, leaving /etc/default/grub edited and grub.cfg untouched. That staged edit would then activate silently at the next kernel update. Prefer /boot/grub2/grub.cfg when it exists, fall back to the EFI path for older layouts, and treat a failed regeneration as a warning rather than a fatal error: by that point the modules are already in place. Also patch existing BLS entries with grubby. Regenerating grub.cfg only affects entries created afterwards, so on a BLS system the parameters never reached the kernel that was actually booting.