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Date:   Mon, 3 Jul 2023 09:51:41 +0530
From:   Sunil V L <sunilvl@ventanamicro.com>
To:     Conor Dooley <conor@kernel.org>
Cc:     Yunhui Cui <cuiyunhui@bytedance.com>, 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
Subject: Re: [PATCH v2 1/3] riscv: obtain ACPI RSDP from FFI.
Message-ID: <ZKJM1fG3JXEBApfj@sunil-laptop>
References: <20230702095735.860-1-cuiyunhui@bytedance.com>
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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 "foreign
> 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 we
> 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.

In case this is approved, I am wondering why do we need new FFI?

[1] - https://lists.riscv.org/g/tech-brs

Thanks!
Sunil