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