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From:   Ilias Apalodimas <ilias.apalodimas@linaro.org>
Date:   Thu, 28 Jul 2022 15:24:15 +0300
Message-ID: <CAC_iWjLkSkON99xXoXphY4JWDZXy_OuOye3T_vPru8aj+j=abw@mail.gmail.com>
Subject: Re: [PATCH 4/4] dt-bindings: firmware: Add Qualcomm UEFI Secure
 Application client
To:     Sudeep Holla <sudeep.holla@arm.com>
Cc:     Maximilian Luz <luzmaximilian@gmail.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Ard Biesheuvel <ardb@kernel.org>,
        Konrad Dybcio <konrad.dybcio@somainline.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Steev Klimaszewski <steev@kali.org>,
        Shawn Guo <shawn.guo@linaro.org>,
        Cristian Marussi <cristian.marussi@arm.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-arm-msm@vger.kernel.org, linux-efi@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
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On Thu, 28 Jul 2022 at 14:33, Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> On Thu, Jul 28, 2022 at 12:48:19PM +0200, Maximilian Luz wrote:
>
> [...]
>
> >
> > I would very much like to avoid the need for special bootloaders. The
> > devices we're talking about are WoA devices, meaning they _should_
> > ideally boot just fine with EFI and ACPI.
> >
>
> Completely agreed.

This is not a special bootloader though.  Quite the opposite.  It's a
standard UEFI compliant bootloader, which uses the fact that EFI is
supposed to be extensible.  It installs a linux specific config table,
similar to how we install a linux specific protocol to load our initrd
and it's certainly lot more scalable than adding new stuff to the
device tree.

>
> > From an end-user perspective, it's annoying enough that we'll have to
> > stick with DTs for the time being due to the use of PEPs in ACPI.
>
> But have we explored or investigated what it takes to rewrite ACPI f/w
> to just use standard methods ? Does it require more firmware changes or
> new firmware entities or impossible at any cost ?
>
> For me that is more important than just getting this one on DT. Because
> if you take that path, we will have to keep doing that, with loads of
> unnecessary drivers if they are not shared with any other SoC with DT
> support upstream. We might also miss chance to get things added to the ACPI
> spec as we don't care which means that we never be able to use ACPI on
> similar future platforms even though they get shipped with ACPI.
>
> It will be a loop where we constantly keep converting this ACPI shipped
> platform into DT upstream. IMHO we don't want to be there.
>
> --
> Regards,
> Sudeep

Regards
/Ilias