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Date:   Fri, 3 Jun 2022 17:27:02 +0800
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Subject: Re: [PATCH V15 11/24] LoongArch: Add boot and setup routines
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To:     Ard Biesheuvel <ardb@kernel.org>,
        Huacai Chen <chenhuacai@loongson.cn>,
        Arnd Bergmann <arnd@arndb.de>,
        Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Airlie <airlied@linux.ie>,
        Jonathan Corbet <corbet@lwn.net>,
        Linus Torvalds <torvalds@linux-foundation.org>
Cc:     linux-arch@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, Xuefeng Li <lixuefeng@loongson.cn>,
        Yanteng Si <siyanteng@loongson.cn>,
        Huacai Chen <chenhuacai@gmail.com>,
        Guo Ren <guoren@kernel.org>, Xuerui Wang <kernel@xen0n.name>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        linux-efi@vger.kernel.org, WANG Xuerui <git@xen0n.name>,
        Yun Liu <liuyun@loongson.cn>
References: <20220603072053.35005-1-chenhuacai@loongson.cn>
 <20220603072053.35005-12-chenhuacai@loongson.cn>
From:   WANG Xuerui <kernel@xen0n.name>
In-Reply-To: <20220603072053.35005-12-chenhuacai@loongson.cn>
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Hi Ard,

On 6/3/22 15:20, Huacai Chen wrote:
> Add basic boot, setup and reset routines for LoongArch. Now, LoongArch
> machines use UEFI-based firmware. The firmware passes configuration
> information to the kernel via ACPI and DMI/SMBIOS.
>
> Currently an existing interface between the kernel and the bootloader
> is implemented. Kernel gets 2 values from the bootloader, passed in
> registers a0 and a1; a0 is an "EFI boot flag" distinguishing UEFI and
> non-UEFI firmware, while a1 is a pointer to an FDT with systable,
> memmap, cmdline and initrd information.
>
> The standard UEFI boot protocol (EFISTUB) will be added later.
>
> Cc: linux-efi@vger.kernel.org
> Cc: Ard Biesheuvel <ardb@kernel.org>
> Reviewed-by: WANG Xuerui <git@xen0n.name>
> Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> Co-developed-by: Yun Liu <liuyun@loongson.cn>
> Signed-off-by: Yun Liu <liuyun@loongson.cn>
> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Would you please look at this patch, which has all the arch-independent 
changes backed out, and Ack if it is fit for mainlining?

I communicated a little with Huacai about the approach for supporting 
alternative boot protocols down the road, and we agreed to carry the 
respective changes downstream. And if needs truly arise for modifying 
common EFI logic, we can do so in a non-rushed manner later.

For the current status of the code, apparently it just accepts the 
standard efistub-shape FDT pointer from (whatever booting the image), 
and everything onwards are fully using the common code without 
modification as you can see from the diffstat. I rebased my BPI support 
patch on top of this (basically translating Loongson BPI data structures 
into the expected FDT form), and can confirm the boot can progress to 
the same point as before -- indeed the SVAM changes etc. are not 
necessary for a working system, and the code remains working.

Thanks in advance.