Messages in this thread | | | From | Adam Ford <> | Date | Fri, 24 Jan 2020 09:54:10 -0600 | Subject | Re: [PATCH] soc: imx: Makefile: only build soc-imx8 when CONFIG_ARM64 |
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On Wed, Jan 15, 2020 at 4:39 AM Arnd Bergmann <arnd@arndb.de> wrote: > > On Wed, Jan 15, 2020 at 3:38 AM Peng Fan <peng.fan@nxp.com> wrote: > > > Subject: Re: [PATCH] soc: imx: Makefile: only build soc-imx8 when CONFIG_ARM64 > > > On Tue, Jan 14, 2020 at 9:32 AM Peng Fan <peng.fan@nxp.com> wrote: > > > > > Subject: Re: [PATCH] soc: imx: Makefile: only build soc-imx8 when > > > > > > > > There is no SOC_IMX8 currently. Need to introduce one in > > > > arch/arm64/Kconfig.platforms. But I not see other vendors introduce > > > > options like SOC_XX. Is this the right direction to add one in > > > > Kconfig.platforms? > > > > > > I think it would be more consistent with the other platforms to have a symbol > > > in drivers/soc/imx/Kconfig to control whether we build that driver. > > > > Ok, I'll add Kconfig entry in drivers/soc/imx/Kconfig for various i.MX SoCs. > > I was thinking of one entry for this driver. > > > > For some SoCs, we also allow running 32-bit kernels, so it would not be wrong > > > to allow enabling the symbol on 32-bit ARM as well, but this is probably > > > something where you want to consider the bigger picture to see if you want > > > to support that configuration or not. > > > > Does the current upstream kernel support 32bit kernels on ARM64 platforms > > without vendor specific stuff. I recalled that several years ago, NXP people > > tried to upstream 32bit kernel support, but rejected by you. > > We have at least some Broadcom SoCs that are supported this way. As > long as you can use the same dtb file on a regular multi_v7_defconfig > I see no problem with doing this. > > What I would like to avoid though are ports that require extra code in > arch/arm/mach-* that is not needed for the 64-bit target, or ports to > 64-bit hardware that only run in 32-bit mode. > > > So Is there any plan to support 32bit kernel on AARCH64 in upstream > > kernel? > > Or any suggestions? > > I don't think there should be 32-bit kernel running in aarch64-ilp32 > mode. This was discussed way back when the aarch64-ilp32 user > space patches first appeared. > > Generally speaking you are usually better off running an aarch64 > kernel using aarch32 user space, but there may be reasons for > running an ARMv8 aarch32 kernel on the same hardware and there > is no technical reason why this shouldn't work for a clean port. > > We never really supported ARMv8-aarch32 in arch/arm/ as a > separate target, but usually building an ARMv7 kernel is close > enough to ARMv8-aarch32 that things just work. If you would > like to help out making ARMv7VE and ARMv8-aarch64 proper > targets for arch/arm/, let me know and we can discuss what parts > are missing.
I would be interested in learning more about running the i.MX8M in 32-bit mode. I'm looking at running Linux on a device with < 1GB of RAM, so having 32-bit pointers and instructions would be preferred. My preference would be to run as ARMv7 for migration purposes, but I'm open to alternatives.
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?
adam
> > Arnd > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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