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Thread-Topic: Running/building an 32 bits kernel on A53 CPU? 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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 2021-10-29 at 11:09 +0100, Catalin Marinas wrote: > On Fri, Oct 29, 2021 at 08:27:35AM +0000, Joakim Tjernlund wrote: > > In order to reduce RAM usage we are wondering if running an 32 bits > > kernel on ARM A53 CPU is a good idea? > > No. Really. > > What's the RAM size on your SoC? 32MB + 4MB SRAM > > > Is it possible to build such a kernel? If so, how to go about it? > > Should one use ARCH=arm and a 32 bits toolchain or > > ARCH=arm64 and 64 bits toolchain and adding 32 bits compile options? > > If you want a 32-bit kernel, you'd have to use ARCH=arm and a 32-bit > toolchain. This would give you an ARMv7 kernel that can run on ARMv8 > hardware. But you'd miss errata workarounds for example and any other > features that come with ARMv8. > > I don't recommend this at all. If you have some specific embedded > system, you can disable kernel features you don't need to make it > smaller. Also note that you can still run 32-bit applications with a > 64-bit kernel. > I have built the smallest kernel I can(so I think ATM), disabling all the features we don't need. We do need IPv4/IPv6 though so that builds size. ATM the my memory consumption is(without starting any user space): Memory: 23924K/32768K available (3584K kernel code, 688K rwdata, 568K rodata, 320K init, 244K bss, 8844K reserved, 0K cma-reserved) The reserved size is about twice the size of static kernel use, any way to lower the dynamic part? _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel