On Tue, Jul 28, 2020 at 12:32 AM Greg Thelen <gthe...@google.com> wrote:
>
> selftests can be built from the toplevel kernel makefile (e.g. make
> kselftest-all) or directly (make -C tools/testing/selftests all).
>
> The toplevel kernel makefile explicitly disables implicit rules with
> "MAKEFLAGS += -rR", which is passed to tools/testing/selftests. Some
> selftest makefiles require implicit make rules, which is why
> commit 67d8712dcc70 ("selftests: Fix build failures when invoked from
> kselftest target") reenables implicit rules by clearing MAKEFLAGS if
> MAKELEVEL=1.
>
> So far so good. However, if the toplevel makefile is called from an
> outer makefile then MAKELEVEL will be elevated, which breaks the
> MAKELEVEL equality test.
> Example wrapped makefile error:
> $ cat ~/Makefile
> all:
> $(MAKE) defconfig
> $(MAKE) kselftest-all
> $ make -sf ~/Makefile
> futex_wait_timeout.c /src/tools/testing/selftests/kselftest_harness.h
> /src/tools/testing/selftests/kselftest.h ../include/futextest.h
> ../include/atomic.h ../include/logging.h -lpthread -lrt -o
> /src/tools/testing/selftests/futex/functional/futex_wait_timeout
> make[4]: futex_wait_timeout.c: Command not found
>
> Rather than checking $(MAKELEVEL), check for $(LINK.c), which is a more
> direct side effect of "make -R". This enables arbitrary makefile
> nesting.
>
> Signed-off-by: Greg Thelen <gthe...@google.com>
> ---
> tools/testing/selftests/Makefile | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/Makefile
> b/tools/testing/selftests/Makefile
> index 1195bd85af38..289a2e4b3f6f 100644
> --- a/tools/testing/selftests/Makefile
> +++ b/tools/testing/selftests/Makefile
> @@ -84,10 +84,10 @@ endif
> # of the targets gets built.
> FORCE_TARGETS ?=
>
> -# Clear LDFLAGS and MAKEFLAGS if called from main
> -# Makefile to avoid test build failures when test
> -# Makefile doesn't have explicit build rules.
> -ifeq (1,$(MAKELEVEL))
> +# Clear LDFLAGS and MAKEFLAGS when implicit rules are missing. This provides
> +# implicit rules to sub-test Makefiles which avoids build failures in test
> +# Makefile that don't have explicit build rules.
> +ifeq (,$(LINK.c))
> override LDFLAGS =
> override MAKEFLAGS =
> endif
> --
> 2.28.0.rc0.142.g3c755180ce-goog
Is there any feedback on this patch? It's not high priority but something that
will help me make more use of selftests.
