On Mon, Apr 4, 2022 at 9:14 PM Max Filippov <jcmvbkbc@xxxxxxxxx> wrote: > On Mon, Apr 4, 2022 at 12:01 PM Arnd Bergmann <arnd@xxxxxxxx> wrote: > > On Mon, Apr 4, 2022 at 7:57 PM Max Filippov <jcmvbkbc@xxxxxxxxx> wrote: > > > Please let me know if you observe any specific build/runtime issues. > > xtensa-linux-gcc-11.1.0 -DKCONFIG_SEED= > ... > > /git/arm-soc/arch/xtensa/kernel/head.S: Assembler messages: > > /git/arm-soc/arch/xtensa/kernel/head.S:87: Error: invalid register > > 'atomctl' for 'wsr' instruction > > Sure, one cannot use an arbitrary xtensa compiler for the kernel > build, the compiler configuration must match the core variant selected > in the linux configuration. Specifically, for the nommu_kc705_defconfig > the following compiler can be used: > > https://github.com/foss-xtensa/toolchain/releases/download/2020.07/x86_64-2020.07-xtensa-de212-elf.tar.gz > > If you build the toolchain yourself using crosstool-ng or buildroot they > accept the 'configuration overlay' parameter that does the compiler > customization. > > Perhaps the documentation for this part is what needs to be improved. It sounds like a bug in the kernel Makefile. On all other architectures, you can generally just pick any (recent) compiler and build any kernel, as the compiler arguments set the exact target machine type based on the kernel config. You can't normally rely on the compiler defaults for kernel builds. Arnd
