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From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Mon, 9 Aug 2021 14:49:28 +0200
Message-ID: <CAMj1kXFUpb6JYndtX9LPpr-dOFQ2-m7n0z70+7Bh-JHhnfoMpw@mail.gmail.com>
Subject: Re: [PATCH 4/5] ARM: Add basic support for EcoNet EN7523 SoC
To:     Geert Uytterhoeven <geert@linux-m68k.org>
Cc:     Bert Vermeulen <bert@biot.com>, Arnd Bergmann <arnd@arndb.de>,
        DTML <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Russell King <linux@armlinux.org.uk>,
        Linus Walleij <linus.walleij@linaro.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
        John Crispin <john@phrozen.org>,
        YiFei Zhu <yifeifz2@illinois.edu>,
        Mike Rapoport <rppt@kernel.org>,
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        Nick Desaulniers <ndesaulniers@google.com>,
        Kees Cook <keescook@chromium.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Viresh Kumar <viresh.kumar@linaro.org>,
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On Mon, 9 Aug 2021 at 14:46, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hoi Bert,
>
> On Wed, Aug 4, 2021 at 6:43 PM Bert Vermeulen <bert@biot.com> wrote:
> > On 7/30/21 4:48 PM, Arnd Bergmann wrote:
> > > On Fri, Jul 30, 2021 at 3:45 PM Bert Vermeulen <bert@biot.com> wrote:
> > >> diff --git a/arch/arm/Makefile b/arch/arm/Makefile
> > >> index 173da685a52e..1bff0aa29c07 100644
> > >> --- a/arch/arm/Makefile
> > >> +++ b/arch/arm/Makefile
> > >> @@ -152,6 +152,7 @@ textofs-$(CONFIG_ARCH_MSM8X60) := 0x00208000
> > >>  textofs-$(CONFIG_ARCH_MSM8960) := 0x00208000
> > >>  textofs-$(CONFIG_ARCH_MESON) := 0x00208000
> > >>  textofs-$(CONFIG_ARCH_AXXIA) := 0x00308000
> > >> +textofs-$(CONFIG_ARCH_ECONET) := 0x00088000
> > >
> > > Why is this needed?
> > >
> > > Note also the comment directly above it exlaining
> > > # Text offset. This list is sorted numerically by address in order to
> > > # provide a means to avoid/resolve conflicts in multi-arch kernels.
> >
> > I didn't make that patch, but it turns out it's needed to get PSCI working;
> > detection hangs without it. That makes no sense to me, but I'll examine further.
>
> Probably PSCI relies on the memory contents at the start of RAM not
> being overwritten?
> Does it help if you remove the first 512 KiB from the /memory node

I /think/ we rely on the first memblock being mappable using section
mappings, so it might be better to remove the first 1 MB (or 2 MB in
case the platform is LPAE capable). Note that this memory is discarded
in any case, so this change is not as costly as it may seem.


> (which should be declared in en7523-evb.dts instead of en7523.dtsi
> BTW)?
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds