Dom0 update errors, dracut warning

I’m using an USB keyboard. I created sys-usb after install using the salt script and gave the keyboard permission to enter the LUKS passphrase during boot. This has been fine for months.

During the latest Dom0 update (4.1-rc3) a lot of errors rolled over the screen, too fast to read. The update ended normally, but I no longer had access to the system, probably because of a sys-usb problem.

So I rebooted by switching the machine off and on again, all seems to work again, except now I got this new warning during boot:

dracut: warning USB in Dom0 is not restricted

This sounds ominous, what to do?

(FWIW journalctl reports a lot of qrexec-client errors, for example: “qubes.InputKeyboard: sys-usb > dom0: error while executing: qrexec-client failed”)

After analyzing the journalctl report, the errors during the upgrade to 4.1 were all qrexec errors. Maybe these errors occurred because qrexec-agent in the templateVM’s couldn’t talk to the the newly installed qrexec-client or daemon in Dom0, since all these errors disappeared after updating the templates. Now the VM’s talk to Dom0 via Qrexec, no more errors.

Still the question remains, what does the dracut warning

‘USB in Dom0 is not restricted’

mean? Maybe this is normal when using an USB-keyboard to enter the LUKS passphrase?