[PATCH v2] kbuild: Avoid including architecture-specific Makefile twice

[Fabio Estevam]

Hi Yao,

On Fri, Jul 11, 2025 at 5:53 AM Yao Zi <ziyao at disroot.org> wrote:
>
> Stranges errors are observed when building U-Boot master for almost any
> RISC-V board, the messages are in two types, one is about duplicated
> symbols,
>
>         u-boot/arch/riscv/cpu//mtrap.S:32: multiple definition of `trap_entry';
>         arch/riscv/cpu/mtrap.o: u-boot/arch/riscv/cpu//mtrap.S:32: first defined here
>
> and the other is fixdep's complaint about missing dependency files,
>
>         fixdep: error opening file: arch/riscv/cpu/.mtrap.o.d: No such file or directory
>         fixdep: error opening file: arch/riscv/cpu//.start.o.d: No such file or directory
>
> where the latter could only be reproduced when building parallelly.
>
> Both the two types of errors are about files in arch/riscv/cpu, and
> there's a suspicious slash character in the reported path. Looking
> through RISC-V-specific Makefiles, there's only one place that may
> expand to such a path,
>
>         libs-y += arch/riscv/cpu/$(CPU)/
>
> The right hand expands to "arch/riscv/cpu//" if $(CPU) isn't defined at
> the time of including. With some debug statement added to
> arch/riscv/Makefile, the output proves that arch/riscv/Makefile is
> included twice, once with $(CPU) undefined and once defined correctly
> according to CONFIG_SYS_CPU.
>
> Futher bisecting shows an extra include statement against
> arch/$(SRCARCH)/Makefile is added in earlier bump of Kbuild system. But
> the statement is evaluated before config.mk is included and definition
> of $(CPU), causing objects in arch/riscv/cpu/ are built and linked twice
> (once as "arch/riscv/cpu/*", and once as "arch/riscv/cpu//*"), resulting
> in the error.
>
> Let's simply remove the extra include to fix these nasty errors. For
> config targets, bumping Kbuild also introduced a new include to
> arch/$(SRCARCH)/Makefile, which is removed as well for consistency.
>
> Fixes: 5f520875bdf ("kbuild: Bump the build system to 5.1")
> Signed-off-by: Yao Zi <ziyao at disroot.org>
> Reviewed-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>

This fixes the mx6sabresd_defconfig build, thanks:

Tested-by: Fabio Estevam <festevam at gmail.com>