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Subject[PATCH 050/161] tools/perf/build: Fix O=/some/dir perf.o type of targets
From: Ingo Molnar <>

If someone specifies a single target, mixed with O=, the following way:

hubble:~/tip/tools/perf> make O=/tmp/perf util/stat.o
BUILD: Doing 'make -j8' parallel build
gcc -Wbad-function-cast -Wdeclaration-after-statement -Wformat-security -Wformat-y2k [...]

The build might even fail, if a target depends on other targets:

hubble:~/tip/tools/perf> make O=/tmp/perf perf.o
perf.c: In function ‘handle_options’:
perf.c:155:21: error: ‘PERF_HTML_PATH’ undeclared (first use in this function)

The correct way to invoke such targets is:

hubble:~/tip/tools/perf> make O=/tmp/perf /tmp/perf/perf.o
BUILD: Doing 'make -j8' parallel build
GEN /tmp/perf/common-cmds.h
CC /tmp/perf/perf.o

But that's unnecessary typing and it's also easy to mistakenly build into the
source directory.

To fix this remove the generic suffix rules and add redirection to $(OUTPUT)
for the most popular .o targets.

Cc: Arnaldo Carvalho de Melo <>
Cc: Peter Zijlstra <>
Cc: Namhyung Kim <>
Cc: David Ahern <>
Cc: Jiri Olsa <>
Signed-off-by: Ingo Molnar <>
tools/perf/Makefile.perf | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 178a1c87db13..a24f6c280b95 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -576,7 +576,21 @@ $(OUTPUT)perf.o perf.spec \

-.SUFFIXES: .o .c .S .s
+# If a target does not match any of the later rules then prefix it by $(OUTPUT)
+# This makes targets like 'make O=/tmp/perf perf.o' work in a natural way.
+ifneq ($(OUTPUT),)
+%.o: $(OUTPUT)%.o
+ @echo " # Redirected target $@ => $(OUTPUT)$@"
+util/%.o: $(OUTPUT)util/%.o
+ @echo " # Redirected target $@ => $(OUTPUT)util/$@"
+bench/%.o: $(OUTPUT)bench/%.o
+ @echo " # Redirected target $@ => $(OUTPUT)bench/$@"
+tests/%.o: $(OUTPUT)tests/%.o
+ @echo " # Redirected target $@ => $(OUTPUT)tests/$@"

# These two need to be here so that when O= is not used they take precedence
# over the general rule for .o
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