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 <20220518092619.1269111-10-chenhuacai@loongson.cn> <14f922495a09898017e4db3baed5b434acadac12.camel@xry111.site>
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From:   Huacai Chen <chenhuacai@gmail.com>
Date:   Tue, 24 May 2022 18:59:50 +0800
Message-ID: <CAAhV-H4BHUTshe2w-KnJ3hLveaFWRJihyDwnOnAbSYWDV_18LA@mail.gmail.com>
Subject: Re: [PATCH V11 09/22] LoongArch: Add boot and setup routines
To:     Xi Ruoyao <xry111@xry111.site>, lichao@loongson.cn
Cc:     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>,
        linux-arch <linux-arch@vger.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Xuefeng Li <lixuefeng@loongson.cn>,
        Yanteng Si <siyanteng@loongson.cn>,
        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 <linux-efi@vger.kernel.org>,
        Ard Biesheuvel <ardb@kernel.org>
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Hi, Ruoyao,

On Tue, May 24, 2022 at 4:27 PM Xi Ruoyao <xry111@xry111.site> wrote:
>
> On Wed, 2022-05-18 at 17:26 +0800, Huacai Chen wrote:
> > 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.
>
> If I understand this correctly, we can:
>
> - set a0 to 0
> - set a1 a pointer (virtual address or physical address?) to the FDT
> with these information
>
> in the bootloader before invoking the kernel, then it will be possible
> to boot this kernel w/o firmware update?
Unfortunately, there is no released firmware for you since we recently
changed the interface again and again. :(
You can contact with Li Chao (lichao@loongson.cn), I think he can
provide help as much as possible (at least provide temporary firmwares
for developers).
We will also provide qemu-system and virtual machine's firmware as
soon as possible.

Huacai

>
> I'd prefer to receive a firmware update anyway, but we need an
> alternative if some vendor just say "no way, our customized distro works
> fine and you should use it".  (I'm not accusing LoongArch: such annoying
> behavior is common among vendors of all architectures, and even worse
> with x86 because they often say "just use Windoge".)
> --
> Xi Ruoyao <xry111@xry111.site>
> School of Aerospace Science and Technology, Xidian University