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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Mon, 27 Jan 2020 07:53:13 +0100
Message-ID: <CAK8P3a2gOq=qv5C6_0QwBXPuENqhBinK_KkzL5AcAEJtTDyB1w@mail.gmail.com>
Subject: Re: [PATCH] soc: imx: Makefile: only build soc-imx8 when CONFIG_ARM64
To:     Peng Fan <peng.fan@nxp.com>
Cc:     Adam Ford <aford173@gmail.com>, Abel Vesa <abel.vesa@nxp.com>,
        Anson Huang <anson.huang@nxp.com>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>,
        "s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        dl-linux-imx <linux-imx@nxp.com>,
        "kernel@pengutronix.de" <kernel@pengutronix.de>,
        =?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        Leonard Crestez <leonard.crestez@nxp.com>,
        "festevam@gmail.com" <festevam@gmail.com>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>
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On Mon, Jan 27, 2020 at 6:05 AM Peng Fan <peng.fan@nxp.com> wrote:
> > Subject: Re: [PATCH] soc: imx: Makefile: only build soc-imx8 when
> > Does anyone have any suggestions on where I might find some generic stuff
> > for either iMX8M or generic ARMv8 docs for doing something like this?
>
> We did a porting for one customer, but code is not public available.
>
> First let uboot switch to AARCH32 mode when booting Linux, this is already
> supported by uboot mailine.
>
> Second, create a mach-imx8m.c under arch/arm/mach-imx to handle i.MX8M
> just like other i.mx arm32 socs. This is not preferred by Linux community.
>
> 3rd, build i.MX8M drivers when using imx_v7_defconfig( or imx_v6_v7_defconfig
> in upstream)

I think the third part is something we can clearly do once it actually boots.

Can you post the patch for the second part for reference? In theory nothing
should be necessary there, so I wonder what I'm missing (as we need no
code for arch/arm64) and what we can do differently to make it work out of
the box.

Is the problem that the SMP bringup using PSCI for arm64 doesn't work
with the 32-bit kernel for some reason?

      Arnd