Re: [External] [PATCH v2 1/3] riscv: obtain ACPI RSDP from FFI.

From: Jessica Clarke <jrtc27@jrtc27.com>
To: Emil Renner Berthing <emil.renner.berthing@gmail.com>
Cc: 运辉崔 <cuiyunhui@bytedance.com>,
	"Andrew Jones" <ajones@ventanamicro.com>,
	"Ard Biesheuvel" <ardb@kernel.org>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Paul Walmsley" <paul.walmsley@sifive.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	linux-riscv <linux-riscv@lists.infradead.org>,
	rminnich@gmail.com, "Mark Rutland" <mark.rutland@arm.com>,
	"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	"Len Brown" <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 <linux-kernel@vger.kernel.org>,
	linux-acpi@vger.kernel.org, geshijian@bytedance.com,
	weidong.wd@bytedance.com
Subject: Re: [External] [PATCH v2 1/3] riscv: obtain ACPI RSDP from FFI.
Date: Mon, 3 Jul 2023 22:32:53 +0100	[thread overview]
Message-ID: <50F3BD62-78F1-456E-A44A-0C7D9A2D4113@jrtc27.com> (raw)
In-Reply-To: <CANBLGcwcvK55dZ1__wvWCtcw=XoKt=qki8g6C_QYo+TBqqJ=TA@mail.gmail.com>

On 3 Jul 2023, at 19:58, Emil Renner Berthing <emil.renner.berthing@gmail.com> wrote:
> 
> On Mon, 3 Jul 2023 at 15:33, 运辉崔 <cuiyunhui@bytedance.com> wrote:
>> 
>> Hi drew,
>> 
>> On Mon, Jul 3, 2023 at 9:01 PM Andrew Jones <ajones@ventanamicro.com> wrote:
>>> 
>>> 
>>> (This is a reply to a non-existent cover letter.)
>> 
>> This has been discussed many times with Ard, Please refer to :
>> https://patches.linaro.org/project/linux-acpi/patch/20230426034001.16-1-cuiyunhui@bytedance.com/
> 
> Hi Yunhui,
> 
> From that discussion it was mentioned that that arm supports 3 methods
> of booting:
>  direct + devicetree
>  EFI + devicetree
>  EFI + ACPI
> ..but not
>  direct + ACPI
> 
> To me it isn't obvious from that or this thread, and since arm seems
> to be doing fine without the 4th option I'm curious why that's
> necessary on riscv?

If anything we should be removing option 1, because that’s not a
cross-OS standard (though RISC-V’s SBI direct booting is at least not
tied to the OS). Any application-class platform spec is going to
mandate EFI, because, whatever your thoughts of EFI are, that is *the*
standard. And if you’re willing to pick up all the complexity of ACPI,
what’s a bit of EFI (especially if you only go for a minimal one a la
U-Boot)?

Jess

>>> I'm not a big fan of adding yet another interface. Have you considered
>>> doing something like [1]?
>>> 
>>> [1] https://github.com/tianocore/tianocore.github.io/wiki/UefiPayloadPkg
> 
> Also you didn't answer this question, which I'd also like to hear a reply to.
> 
> /Emil
> 
>>> Thanks,
>>> drew
>> 
>> Thanks,
>> Yunhui
>> 
>> _______________________________________________
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> 
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