On Tue, Aug 6, 2019 at 7:03 PM Masahiro Yamada
<yamada.masahiro@xxxxxxxxxxxxx> wrote:
>
> Since commit ff9b45c55b26 ("kbuild: modpost: read modules.order instead
> of $(MODVERDIR)/*.mod"), a module is no longer built in the following
> pattern:
>
> [Makefile]
> subdir-y := some-module
>
> [some-module/Makefile]
> obj-m := some-module.o
>
> You cannot write Makefile this way in upstream because modules.order is
> not correctly generated. subdir-y is used to descend to a sub-directory
> that builds tools, device trees, etc.
>
> For external modules, the modules order does not matter. So, the
> Makefile above was known to work.
>
> I believe the Makefile should be re-written as follows:
>
> [Makefile]
> obj-m := some-module/
>
> [some-module/Makefile]
> obj-m := some-module.o
>
> However, people will have no idea if their Makefile suddenly stops
> working. In fact, I received questions from multiple people.
>
> Show a warning if obj-m is specified in a Makefile visited by subdir-y
> or subdir-m.
>
> Cc: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
> Cc: Tom Stonecypher <thomas.edwardx.stonecypher@xxxxxxxxx>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
> ---
This produces false-positive warnings for single-targets.
I will fix up as follows:
diff --git a/Makefile b/Makefile
index 0e37ad2f77bf..fac25e279da6 100644
--- a/Makefile
+++ b/Makefile
@@ -1783,7 +1783,7 @@ PHONY += /
/: ./
%/: prepare FORCE
- $(Q)$(MAKE) KBUILD_MODULES=1 $(build)=$(build-dir)
+ $(Q)$(MAKE) KBUILD_MODULES=1 $(build)=$(build-dir) need-modorder=1
# FIXME Should go into a make.lib or something
# ===========================================================================
>
> scripts/Makefile.build | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 37a1d2cd49d4..4a26c7ed9198 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -52,6 +52,13 @@ ifndef obj
> $(warning kbuild: Makefile.build is included improperly)
> endif
>
> +ifeq ($(need-modorder),)
> +ifneq ($(obj-m),)
> +$(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.)
> +$(warning You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.)
> +endif
> +endif
> +
> # ===========================================================================
>
> ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
> --
> 2.17.1
>
--
Best Regards
Masahiro Yamada
