Date: Tue, 25 Aug 2015 15:24:16 +0100
From: Leif Lindholm <leif.lindholm@linaro.org>
To: Haojian Zhuang <haojian.zhuang@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
        "leo.yan@linaro.org" <leo.yan@linaro.org>,
        Rob Herring <robh+dt@kernel.org>, Pawel Moll <Pawel.Moll@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Kumar Gala <galak@codeaurora.org>,
        Catalin Marinas <Catalin.Marinas@arm.com>,
        Will Deacon <Will.Deacon@arm.com>,
        Jassi Brar <jassisinghbrar@gmail.com>,
        Bintian Wang <bintian.wang@huawei.com>,
        Yiping Xu <xuyiping@hisilicon.com>, Wei Xu <xuwei5@hisilicon.com>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
        "guodong.xu@linaro.org" <guodong.xu@linaro.org>,
        Jian Zhang <zhangjian001@hisilicon.com>,
        Zhenwei Wang <Zhenwei.wang@hisilicon.com>,
        Haoju Mo <mohaoju@hisilicon.com>, Dan Zhao <dan.zhao@hisilicon.com>,
        "kongfei@hisilicon.com" <kongfei@hisilicon.com>,
        Guangyue Zeng <zengguangyue@hisilicon.com>
Subject: Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node
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On Tue, Aug 25, 2015 at 09:43:14PM +0800, Haojian Zhuang wrote:
> Since we discussed a lot on this, let's make a conclusion on it.
> 
> 1. UEFI could append the reserved buffer in it's memory mapping.

Yes. It needs to.

(I will let Mark comment on points 2-4.)

> 5. A patch is necessary in kernel. If efi stub feature is enabled,
>    arm kernel should not parse memory node or reserved memory buffer in
>    DT any more.

This is already the case. The stub deletes any present memory nodes and
reserved entries in drivers/firmware/efi/libstub/fdt.c:update_fdt().

Then, during setup_arch(), arch/arm64/kernel/efi.c:efi_init() calls
reserve_regions(), which adds only those memory regions available for
use by Linux as RAM to memblock.

>    Arm kernel should either fetch memory information from 
>    efi or DT.

Absolutely.

>    Currently arm kernel fetch both efi memory information and
>    reserved buffer from DTB at the same time.

No, it does not.

Regards,

Leif
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