[PATCH] perf build: Override OUTPUT when building internal libraries

[Dmitry Safonov via B4 Relay]

From: Dmitry Safonov <dima@xxxxxxxxxx>

After commit 1572ba36fbca ("perf tests: Improvements to build-test
performance"), building perf with OUTPUT on the command line fails:
  make -C tools/perf OUTPUT=/tmp/linux/bld/perf/ ARCH=x86_64 LC_ALL=C CC=gcc HOSTCC=gcc LD=ld
  ...
  make[3]: *** No rule to make target '/tmp/linux/perf/libsubcmd/libsubcmd.a'.  Stop.

MAKEFLAGS propagates the command-line OUTPUT assignment to recursive makes.
The library builds pass their output directories through $O, but the assignment
to $OUTPUT in tools/scripts/Makefile.include cannot replace a command-line
argument. This affects libapi, libperf, libsubcmd and libsymbol.

With "unexport MAKEFLAGS" returned and added $(info) debug in libsubcmd
Makefile produces:
  OUTPUT = /tmp/linux/perf/libsubcmd/
Without it, on current master it prints:
  OUTPUT = /tmp/linux/perf/

Pass OUTPUT explicitly to each library build, including the trailing slash
required when constructing file names. This follows the existing libbpf
build rule and preserves MAKEFLAGS and jobserver propagation.

Fixes: 1572ba36fbca ("perf tests: Improvements to build-test performance")
Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>
---
 tools/perf/Makefile.perf | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index b74b534e1153..4cc5bb3011da 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -798,7 +798,7 @@ $(patsubst perf-%,%.o,$(PROGRAMS)): $(wildcard */*.h)
 
 $(LIBAPI): FORCE | $(LIBAPI_OUTPUT)
 	$(Q)$(MAKE) -C $(LIBAPI_DIR) O=$(LIBAPI_OUTPUT) \
-		DESTDIR=$(LIBAPI_DESTDIR) prefix= subdir= \
+		OUTPUT=$(LIBAPI_OUTPUT)/ DESTDIR=$(LIBAPI_DESTDIR) prefix= subdir= \
 		$@ install_headers
 
 $(LIBAPI)-clean:
@@ -816,7 +816,7 @@ $(LIBBPF)-clean:
 
 $(LIBPERF): FORCE | $(LIBPERF_OUTPUT)
 	$(Q)$(MAKE) -C $(LIBPERF_DIR) O=$(LIBPERF_OUTPUT) \
-		DESTDIR=$(LIBPERF_DESTDIR) prefix= subdir= \
+		OUTPUT=$(LIBPERF_OUTPUT)/ DESTDIR=$(LIBPERF_DESTDIR) prefix= subdir= \
 		$@ install_headers
 
 $(LIBPERF)-clean:
@@ -825,7 +825,7 @@ $(LIBPERF)-clean:
 
 $(LIBSUBCMD): FORCE | $(LIBSUBCMD_OUTPUT)
 	$(Q)$(MAKE) -C $(LIBSUBCMD_DIR) O=$(LIBSUBCMD_OUTPUT) \
-		DESTDIR=$(LIBSUBCMD_DESTDIR) prefix= subdir= \
+		OUTPUT=$(LIBSUBCMD_OUTPUT)/ DESTDIR=$(LIBSUBCMD_DESTDIR) prefix= subdir= \
 		$@ install_headers
 
 $(LIBSUBCMD)-clean:
@@ -834,7 +834,7 @@ $(LIBSUBCMD)-clean:
 
 $(LIBSYMBOL): FORCE | $(LIBSYMBOL_OUTPUT)
 	$(Q)$(MAKE) -C $(LIBSYMBOL_DIR) O=$(LIBSYMBOL_OUTPUT) \
-		DESTDIR=$(LIBSYMBOL_DESTDIR) prefix= subdir= \
+		OUTPUT=$(LIBSYMBOL_OUTPUT)/ DESTDIR=$(LIBSYMBOL_DESTDIR) prefix= subdir= \
 		$@ install_headers
 
 $(LIBSYMBOL)-clean:

---
base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
change-id: 20261103-perf-output-58d6965d2726

Best regards,
--  
Dmitry Safonov <dima@xxxxxxxxxx>