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From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Mon, 18 Jan 2021 14:09:28 +0100
Message-ID: <CACRpkdZiUAi+Ur=v0omivvUnUVe9p2Tntum_DtdOa-uD-sKTuQ@mail.gmail.com>
Subject: Re: [PATCH v12] ARM: uncompress: Validate start of physical memory
 against passed DTB
To:     Geert Uytterhoeven <geert@linux-m68k.org>,
        Rob Herring <robh+dt@kernel.org>
Cc:     Russell King <linux@armlinux.org.uk>,
        Ard Biesheuvel <ardb@kernel.org>,
        Nicolas Pitre <nico@fluxnic.net>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Dmitry Osipenko <digetx@gmail.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Eric Miao <eric.miao@nvidia.com>,
        =?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        Lukasz Stelmach <l.stelmach@samsung.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Chris Brandt <chris.brandt@renesas.com>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Grant Likely <grant.likely@linaro.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Heinrich Schuchardt <xypron.glpk@gmx.de>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>
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On Mon, Jan 11, 2021 at 5:19 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:

> > I suppose we already had a discussion of why this property
> > is undocumented? Or should we document it? Obviously
> > it is already in widespread use.
>
> This comes from commit 51975db0b7333cf3 ("of/flattree: merge
> early_init_dt_scan_memory() common code"), which combined existing
> practises on Microblaze (commit 12e8414263f47352 ("microblaze_v8: Open
> firmware files")) and PowerPC (ba7594852f4e7121 ("[PATCH] powerpc: Add
> support for "linux,usable-memory" on memory nodes")), with the former
> obviously just copying the latter.
> Unfortunately none of this is documented in The DeviceTree
> Specification, ePAPR, or P1275.
>
> Heinrich tried to document it, but his patch was ignored:
> [PATCH] Documentation: devicetree: "linux,usable-memory" property
> https://lore.kernel.org/linux-devicetree/20161223161747.9986-1-xypron.glpk@gmx.de/
> https://lkml.org/lkml/2016/12/23/175
> https://lore.kernel.org/patchwork/patch/745784/
> Note that Heinrichs address is mangled in lore (imported from gmane?,
> but lkml and patchwork have it right.

I bet it's just a mishap.
Rob, can you pick up and apply this patch?

Yours,
Linus Walleij