On Tue, Apr 5, 2022 at 4:28 PM Chris Murphy <lists(a)colorremedies.com> wrote:
On Tue, Apr 5, 2022 at 9:56 AM Florian Weimer <fweimer(a)redhat.com> wrote:
>
> * Peter Robinson:
>
> > This is out of context here because you can disable Secure Boot but
> > still use UEFI to make that work. You're trying to link to different
> > problems together.
>
> I think there's firmware out there which enables Secure Boot
> unconditionally in UEFI mode, but still has CSM support.
The UEFI spec makes CSM and Secure Boot mutually exclusive. CSM
enabled renders Secure Boot impossible. So I'm not sure how the
firmware can simultaneously enforce Secure Boot, but then permit the
loading of non-compliant bootloaders. That'd seem to be a Secure Boot
break worthy of a firmware update. In particular if it's also possible
to invoke CSM boot via NVRAM variables.
Many boards offered this capability, even though it violates the
standard. It's one of the reasons why Intel demanded PC makers stop
supporting CSM at all.
--
真実はいつも一つ!/ Always, there's only one truth!