There's a couple of issues here, not just the one with mokutil -- looks
like your system is also failing to download all the right packages for
your third-party drivers.
I'll fix the failure because of mokutil now; this is simply because
mokutil and the kernel tend to disagree about the result of asking for
disabling validation, and mokutils happens to really do successfully set
things up, regardless of the message shown.
To answer the earlier questions; you can certainly change the Secure
Boot validation status later. This message is intended to convey the
message that if you want to use third-party drivers, you really ought to
disable Secure Boot validation as proposed; otherwise these *drivers*
might not work when you reboot. This is important since drivers may keep
you from getting online (for some wifi drivers), or from starting Unity
(assuming for some reason fallback to the free drivers completely fails,
except it usually doesn't). In other words, you might not get 3D
graphics or wifi if you really depend on the third-party drivers for
those to work.
To make changes later, you can run mokutil:
To re-enable Secure Boot validation:
sudo mokutil --enable-validation
To disable Secure Boot validation (which we do not recommend unless you need
third-party drivers):
sudo mokutil --disable-validation
This is substancially different from disabling Secure Boot altogether.
If you disable Secure Boot, you get no validation at all of the boot
sequence. If you leave it on but disable validation in shim using
mokutil, you will get validation up to Grub, and then the kernel and
modules will not be validated for a good signature by Canonical.
This also means you need to disable validation if you want to use custom
kernels.
For now, we're toggling validation in shim. In the future, we'll work on
making it easy to sign your own built kernels and modules, so that
disabling validation is not required (and then you can more easily make
sure the full boot sequence has not been tampered with).
** Changed in: ubiquity (Ubuntu)
Status: Confirmed => In Progress
** Changed in: ubiquity (Ubuntu)
Assignee: (unassigned) => Mathieu Trudel-Lapierre (cyphermox)
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https://bugs.launchpad.net/bugs/1567445
Title:
ubi-prepare failed with exit code 255
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