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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Fri, 17 Dec 2021 11:28:43 +0100
Message-ID: <CAK8P3a3kpzi6ozLkTH9GtWqvs=JHkm6mp=dLs2vOHjrW=FoYdw@mail.gmail.com>
Subject: Re: [RESEND in plain-test] Re: [PATCH v5 0/9] Add initial support for
 the i.MXRTxxxx SoC family starting from i.IMXRT1050 SoC.
To:     Giulio Benetti <giulio.benetti@benettiengineering.com>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Jesse Taube <mr.bossman075@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Sascha Hauer <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Dong Aisheng <aisheng.dong@nxp.com>,
        Stefan Agner <stefan@agner.ch>,
        Linus Walleij <linus.walleij@linaro.org>,
        gregkh <gregkh@linuxfoundation.org>,
        Olof Johansson <olof@lixom.net>, SoC Team <soc@kernel.org>,
        Russell King - ARM Linux <linux@armlinux.org.uk>,
        Abel Vesa <abel.vesa@nxp.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Jiri Slaby <jirislaby@kernel.org>,
        Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>,
        linux-clk <linux-clk@vger.kernel.org>,
        DTML <devicetree@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-mmc <linux-mmc@vger.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
        Vladimir Murzin <vladimir.murzin@arm.com>
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On Fri, Dec 17, 2021 at 10:54 AM Giulio Benetti
<giulio.benetti@benettiengineering.com> wrote:
> On 16/12/21 22:13, Arnd Bergmann wrote:
>
> > Vladimir has put some work into making Cortex-R work in the kernel, and
> > he may have some other thoughts on this question.
>
> I'm curious if he has something specific to Cortex-R to tell.
>
> I've found that Cortex-R82 has a MMU:
> https://www.arm.com/products/silicon-ip-cpu/cortex-r/cortex-r82
> but I can't find any SoC that uses it. Also, I don't know how many
> people could use it honestly.

R82 is fairly new, but I expect that we will see support in Linux in the
future. Aside from having an MMU, it also 64-bit-only, so we'd treat
it like a normal ARMv8-A core in arch/arm64.

        Arnd