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 $(LINK.c), which is a more
direct side effect of "make -R". This enables arbitrary makefile
nesting.
Signed-off-by: Greg Thelen <gthelen@xxxxxxxxxx>
---
tools/testing/selftests/Makefile | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 1195bd85af38..289a2e4b3f6f 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -84,10 +84,10 @@ endif
# of the targets gets built.
FORCE_TARGETS ?=
-# Clear LDFLAGS and MAKEFLAGS if called from main
-# Makefile to avoid test build failures when test
-# Makefile doesn't have explicit build rules.
-ifeq (1,$(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
