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

[Ilias Apalodimas]

Hi Yao,


On Wed, 9 Jul 2025 at 19:15, 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. Note
> though this therotically affects all architectures, ones except RISC-V
> may not reproduce similar errors since there are no source files
> directly under arch/*/cpu, thus the extra include doesn't hurt.

There's another unconditional include under ifeq ($(config-targets),1).
Should we remove that as well?

The patch it self seems correct, but can you try removing the
pre-existing include instead and add the config.mk inclusion?
Something like
diff --git a/Makefile b/Makefile
index db8d89587290..e6ad9be262ef 100644
--- a/Makefile
+++ b/Makefile
@@ -636,6 +636,7 @@ ifeq ($(config-targets),1)
 # KBUILD_DEFCONFIG may point out an alternative default configuration
 # used for 'make defconfig'
 # Modified for U-Boot
+include config.mk
 -include arch/$(SRCARCH)/Makefile
 export KBUILD_DEFCONFIG KBUILD_KCONFIG CC_VERSION_TEXT

@@ -725,6 +726,7 @@ ARCH_CPPFLAGS :=
 ARCH_AFLAGS :=
 ARCH_CFLAGS :=
 # Modified for U-Boot
+include config.mk
 -include arch/$(SRCARCH)/Makefile

 ifeq ($(dot-config),1)
@@ -773,10 +775,6 @@ ifneq ($(wildcard $(KCONFIG_CONFIG)),)
 ifneq ($(wildcard include/config/auto.conf),)
 autoconf_is_old := $(shell find . -path ./$(KCONFIG_CONFIG) -newer \
                                                include/config/auto.conf)
-ifeq ($(autoconf_is_old),)
-include config.mk
-include arch/$(ARCH)/Makefile
-endif
 endif
 endif

I prefer keeping the makefile closer to the kernel so we can sync it
up easier in the future

Thanks for looking at this
/Ilias
>
> Fixes: 5f520875bdf ("kbuild: Bump the build system to 5.1")
> Signed-off-by: Yao Zi <ziyao at disroot.org>
> ---
>
> I was surprised to see this morning's CI passed[1] even for these RISC-V
> boards. Builds for SiFive unleashed, QEMU S-Mode virt and Sipeed Lichee
> Pi 4A always fail on my machine with the latest master branch, thus
> maybe I missed some points when digging the issue, please correct me if
> so.
>
> [1]: https://source.denx.de/u-boot/u-boot/-/commit/3833600dbaa2d7008063f3127abf21be8f0fe6cd/pipelines?ref=master
>
>  Makefile | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index da53efa09f1..b610dcc0b6e 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -724,8 +724,6 @@ endif
>  ARCH_CPPFLAGS :=
>  ARCH_AFLAGS :=
>  ARCH_CFLAGS :=
> -# Modified for U-Boot
> --include arch/$(SRCARCH)/Makefile
>
>  ifeq ($(dot-config),1)
>  ifeq ($(may-sync-config),1)
> --
> 2.50.0
>