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From:   =?UTF-8?B?6L+Q6L6J5bSU?= <cuiyunhui@bytedance.com>
Date:   Sat, 8 Jul 2023 11:22:58 +0800
Message-ID: <CAEEQ3wnhCRnDsa2Un=J_VOo2JZqf0nMXX11okqpyhMbLAWsKJQ@mail.gmail.com>
Subject: Re: [External] Re: [PATCH v3 0/4] Obtain SMBIOS and ACPI entry from FFI
To:     Dong Wei <Dong.Wei@arm.com>
Cc:     Conor Dooley <conor@kernel.org>,
        =?UTF-8?B?6JGb5aOr5bu6?= <geshijian@bytedance.com>,
        Sunil V L <sunilvl@ventanamicro.com>,
        Conor Dooley <conor.dooley@microchip.com>,
        ron minnich <rminnich@gmail.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        "jrtc27@jrtc27.com" <jrtc27@jrtc27.com>,
        "kernel@esmil.dk" <kernel@esmil.dk>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        "aou@eecs.berkeley.edu" <aou@eecs.berkeley.edu>,
        "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>,
        Mark Rutland <Mark.Rutland@arm.com>,
        "lpieralisi@kernel.org" <lpieralisi@kernel.org>,
        "rafael@kernel.org" <rafael@kernel.org>,
        "lenb@kernel.org" <lenb@kernel.org>,
        "jdelvare@suse.com" <jdelvare@suse.com>,
        "yc.hung@mediatek.com" <yc.hung@mediatek.com>,
        "angelogioacchino.delregno@collabora.com" 
        <angelogioacchino.delregno@collabora.com>,
        "allen-kh.cheng@mediatek.com" <allen-kh.cheng@mediatek.com>,
        "pierre-louis.bossart@linux.intel.com" 
        <pierre-louis.bossart@linux.intel.com>,
        "tinghan.shen@mediatek.com" <tinghan.shen@mediatek.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>,
        "weidong.wd@bytedance.com" <weidong.wd@bytedance.com>
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Hey,

On Sat, Jul 8, 2023 at 12:39=E2=80=AFAM Dong Wei <Dong.Wei@arm.com> wrote:
>
>
>
> > I don't think that's the limitation on RISC-V. BTW, how does OSPM find =
the
>
> > RSDP on ARM systems? Does it meet 5.2.5?
>
> >
>
>
>
> On Arm systems today, the ACPI RSDP is found using the UEFI Configuration=
 Table. This is true for all Arm SystemReady compliant systems: 1) SystemRe=
ady LS: LBBRv1 is using a minimal UEFI FW to load LinuxBoot, that minimal U=
EFI FW is producing the UEFI Configuration Table. We are working on LBBRv2.=
 LBBRv2 is based on Coreboot loading LinuxBoot. But we do not have a way to=
day to get CoreBoot to produce this pointer to ACPI RSDP. Arm does not supp=
ort x86 E820 BIOS interface. 2) SystemReady IR: this solution uses DT rathe=
r than ACPI. 3) SystemReady ES: this solution can use UBoot or EDK2, and it=
 requires ACPI. Since both UBoot and EDK2 support UEFI now, so ACPI RSDP ca=
n be found using the UEFI Configuration Table. 4) SystemReady SR: this solu=
tion typically uses EDK2 and requires ACPI, so no issue finding RSDP via UE=
FI Configuration Table.

Looks like ARM has a similar problem,
Indeed, as Ron said, many companies may encounter this issue. More
developers are embracing Coreboot. When the platform guided by
Coreboot requires ACPI support, they are faced with how to pass ACPI
RSDP to Linux.

>
>
> So the ACPI RSDP issue only exist if we want to remove the minimum UEFI F=
W and go to CoreBoot completely to load LinuxBoot. We are currently explori=
ng how to solve that issue=E2=80=A6
>
>
>
> -DW
>
>
>
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n any medium. Thank you.

Thanks,
Yunhui