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From:   =?UTF-8?B?6L+Q6L6J5bSU?= <cuiyunhui@bytedance.com>
Date:   Mon, 3 Jul 2023 14:19:46 +0800
Message-ID: <CAEEQ3wnsedWJYEEg8z+3C_HuCca0nD50NGpCdU3scxavrrOucA@mail.gmail.com>
Subject: Re: [External] Re: [PATCH v2 1/3] riscv: obtain ACPI RSDP from FFI.
To:     Sunil V L <sunilvl@ventanamicro.com>
Cc:     Conor Dooley <conor@kernel.org>, ardb@kernel.org,
        palmer@dabbelt.com, paul.walmsley@sifive.com,
        aou@eecs.berkeley.edu, linux-riscv@lists.infradead.org,
        rminnich@gmail.com, mark.rutland@arm.com, lpieralisi@kernel.org,
        rafael@kernel.org, lenb@kernel.org, jdelvare@suse.com,
        yc.hung@mediatek.com, angelogioacchino.delregno@collabora.com,
        allen-kh.cheng@mediatek.com, pierre-louis.bossart@linux.intel.com,
        tinghan.shen@mediatek.com, linux-kernel@vger.kernel.org,
        linux-acpi@vger.kernel.org, geshijian@bytedance.com,
        weidong.wd@bytedance.com, alexghiti@rivosinc.com
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Hi Sunil,

On Mon, Jul 3, 2023 at 12:22=E2=80=AFPM Sunil V L <sunilvl@ventanamicro.com=
> wrote:
>
> Hi Yunhui Cui,
> On Sun, Jul 02, 2023 at 02:47:41PM +0100, Conor Dooley wrote:
> > Hey,
> > %subject: riscv: obtain ACPI RSDP from FFI.
> >
> > This subject is a bit unhelpful because FFI would commonly mean "foreig=
n
> > function interface" & you have not yet introduced it. It seems like it
> > would be better to do s/FFI/devicetree/ or similar.
> > Please also drop the full stop from the commit messages ;)
> >
> > Please use a cover letter for multi-patch series & include changelogs.
> >
> > +CC Sunil, Alex:
> >
> > Can you guys please take a look at this & see if it is something that w=
e
> > want to do (ACPI without EFI)?
> >
>
> We have supported ACPI only with UEFI. The current booting contract
> between firmware and OS is to pass only one of DT or ACPI, not both.
> This approach brings another booting contract for Linux mixing ACPI and
> DT which affects RVI specs. As per policy and since it can affect
> multiple OSs, a frozen RVI spec is required for taking this patch into
> linux. So, could you please bring this topic for discussion in [1] and
> get agreement?
>
> Isn't it simpler to provide a minimum UEFI configuration table and
> stubbed BS/RS?
>
> Have you done a PoC? I am curious how do you handle EFI memory map
> dependencies.

Yes, Poc has been completed.
a memory node in DTS can solve it.

>
> In case this is approved, I am wondering why do we need new FFI?
>
> [1] - https://lists.riscv.org/g/tech-brs

We have discussed with Ard and Ron many times about the series of
questions you mentioned above, and reached a consensus.
Please see the v1:
https://patches.linaro.org/project/linux-acpi/patch/20230426034001.16-1-cui=
yunhui@bytedance.com/

Thanks,
Yunhui