What were you trying to do that didn't work?

Downstream systemd-stub is v252. Starting from v253, "addons" were introduced to be able to extend UKI command line securely.

The main patch is 05c9f9c251 stub: allow loading and verifying cmdline addons. But also all the other following are required.

Steps to reproduce

2 ways to check if systemd-stub is updated:

1) just install the rpm

1. sudo dnf install -y systemd-boot
2. check that /usr/lib/systemd/boot/efi/addonx64.efi.stub exists

2) create an addon (requires ukify https://issues.redhat.com/browse/RHEL-13199)