[PATCH 0/3] Fix out-of-tree build of some tools

[PATCH 0/3] Fix out-of-tree build of some tools

[Ben Hutchings]

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perf and rtla currently don't fully support out-of-tree builds, as
they may still create files in their source directory.  This series
fixes all the instances of this problem that I have found.

Ben.

Ben Hutchings (3):
  rtla: Fix output files in source tree
  perf tools: Put Python egg info in output directory
  perf tools: Put Python bytecode in output directory

 tools/perf/Makefile.perf            |  9 ++++++++-
 tools/tracing/rtla/Makefile         | 31 ++++++++++++++++++-----------
 tools/tracing/rtla/tests/timerlat.t |  4 ++--
 3 files changed, 29 insertions(+), 15 deletions(-)


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[PATCH 1/3] rtla: Fix output files in source tree

[Ben Hutchings]

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Some output files (src/timerlat.bpf.o, src/timerlat.skel.h,
example/timerlat_bpf_action.o, tests/bpf/bpf_action_map.o) are
currently generated in the source tree, preventing a fully out-of-tree
build.  To fix this:

- Add $(OUTPUT) to their filenames in the relevant Makefile rules, and
  create subdirectories as needed
- Add $(OUTPUT)src to the include path
- Add ${OUTPUT} to the BPF object filename in tests/timerlat.t

Fixes: e34293ddcebd ("rtla/timerlat: Add BPF skeleton to collect samples")
Fixes: 0304a3b7ec9a ("rtla/timerlat: Add example for BPF action program")
Fixes: 5525aebd4e0c ("rtla/tests: Test BPF action program")
Signed-off-by: Ben Hutchings <benh@debian.org>
---
 tools/tracing/rtla/Makefile         | 31 ++++++++++++++++++-----------
 tools/tracing/rtla/tests/timerlat.t |  4 ++--
 2 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/tools/tracing/rtla/Makefile b/tools/tracing/rtla/Makefile
index 45690ee14544..f54da7be735d 100644
--- a/tools/tracing/rtla/Makefile
+++ b/tools/tracing/rtla/Makefile
@@ -66,30 +66,37 @@ ifeq ($(config),1)
   include Makefile.config
 endif
 
+INCLUDES	= -I$(OUTPUT)src
+
 CFLAGS		+= $(INCLUDES) $(LIB_INCLUDES)
 
 export CFLAGS OUTPUT srctree
 
 ifeq ($(BUILD_BPF_SKEL),1)
-src/timerlat.bpf.o: src/timerlat.bpf.c
+$(OUTPUT)src/timerlat.bpf.o: src/timerlat.bpf.c
+	mkdir -p $(@D)
 	$(QUIET_CLANG)$(CLANG) -g -O2 -target bpf -c $(filter %.c,$^) -o $@
 
-src/timerlat.skel.h: src/timerlat.bpf.o
+$(OUTPUT)src/timerlat.skel.h: $(OUTPUT)src/timerlat.bpf.o
+	mkdir -p $(@D)
 	$(QUIET_GENSKEL)$(SYSTEM_BPFTOOL) gen skeleton $< > $@
 
-example/timerlat_bpf_action.o: example/timerlat_bpf_action.c
+$(OUTPUT)example/timerlat_bpf_action.o: example/timerlat_bpf_action.c
+	mkdir -p $(@D)
 	$(QUIET_CLANG)$(CLANG) -g -O2 -target bpf -c $(filter %.c,$^) -o $@
 
-tests/bpf/bpf_action_map.o: tests/bpf/bpf_action_map.c
+$(OUTPUT)tests/bpf/bpf_action_map.o: tests/bpf/bpf_action_map.c
+	mkdir -p $(@D)
 	$(QUIET_CLANG)$(CLANG) -g -O2 -target bpf -c $(filter %.c,$^) -o $@
 else
-src/timerlat.skel.h:
-	$(Q)echo '/* BPF skeleton is disabled */' > src/timerlat.skel.h
+$(OUTPUT)src/timerlat.skel.h:
+	mkdir -p $(@D)
+	$(Q)echo '/* BPF skeleton is disabled */' > $@
 
-example/timerlat_bpf_action.o: example/timerlat_bpf_action.c
+$(OUTPUT)example/timerlat_bpf_action.o: example/timerlat_bpf_action.c
 	$(Q)echo "BPF skeleton support is disabled, skipping example/timerlat_bpf_action.o"
 
-tests/bpf/bpf_action_map.o: tests/bpf/bpf_action_map.c
+$(OUTPUT)tests/bpf/bpf_action_map.o: tests/bpf/bpf_action_map.c
 	$(Q)echo "BPF skeleton support is disabled, skipping tests/bpf/bpf_action_map.o"
 endif
 
@@ -103,7 +110,7 @@ static: $(RTLA_IN)
 rtla.%: fixdep FORCE
 	make -f $(srctree)/tools/build/Makefile.build dir=. $@
 
-$(RTLA_IN): fixdep FORCE src/timerlat.skel.h
+$(RTLA_IN): fixdep FORCE $(OUTPUT)src/timerlat.skel.h
 	make $(build)=rtla
 
 clean: doc_clean fixdep-clean
@@ -111,10 +118,10 @@ clean: doc_clean fixdep-clean
 	$(Q)find . -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
 	$(Q)rm -f rtla rtla-static fixdep FEATURE-DUMP rtla-*
 	$(Q)rm -rf feature
-	$(Q)rm -f src/timerlat.bpf.o src/timerlat.skel.h example/timerlat_bpf_action.o
+	$(Q)rm -f $(OUTPUT)src/timerlat.bpf.o $(OUTPUT)src/timerlat.skel.h $(OUTPUT)example/timerlat_bpf_action.o
 	$(Q)rm -f $(UNIT_TESTS)
 
-check: $(RTLA) tests/bpf/bpf_action_map.o
+check: $(RTLA) $(OUTPUT)tests/bpf/bpf_action_map.o
 	RTLA=$(RTLA) BPFTOOL=$(SYSTEM_BPFTOOL) prove -o -f -v tests/
-examples: example/timerlat_bpf_action.o
+examples: $(OUTPUT)example/timerlat_bpf_action.o
 .PHONY: FORCE clean check
diff --git a/tools/tracing/rtla/tests/timerlat.t b/tools/tracing/rtla/tests/timerlat.t
index fd4935fd7b49..e0f3fc4df655 100644
--- a/tools/tracing/rtla/tests/timerlat.t
+++ b/tools/tracing/rtla/tests/timerlat.t
@@ -74,12 +74,12 @@ then
 	# Test BPF action program properly in BPF mode
 	[ -z "$BPFTOOL" ] && BPFTOOL=bpftool
 	check "hist with BPF action program (BPF mode)" \
-		"timerlat hist -T 2 --bpf-action tests/bpf/bpf_action_map.o --on-threshold shell,command='$BPFTOOL map dump name rtla_test_map'" \
+		"timerlat hist -T 2 --bpf-action ${OUTPUT}tests/bpf/bpf_action_map.o --on-threshold shell,command='$BPFTOOL map dump name rtla_test_map'" \
 		2 '"value": 42'
 else
 	# Test BPF action program failure in non-BPF mode
 	check "hist with BPF action program (non-BPF mode)" \
-		"timerlat hist -T 2 --bpf-action tests/bpf/bpf_action_map.o" \
+		"timerlat hist -T 2 --bpf-action ${OUTPUT}tests/bpf/bpf_action_map.o" \
 		1 "BPF actions are not supported in tracefs-only mode"
 fi
 done


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Re: [PATCH 1/3] rtla: Fix output files in source tree

[Steven Rostedt]

On Thu, 21 May 2026 16:35:25 +0200
Ben Hutchings <benh@debian.org> wrote:

> Some output files (src/timerlat.bpf.o, src/timerlat.skel.h,
> example/timerlat_bpf_action.o, tests/bpf/bpf_action_map.o) are
> currently generated in the source tree, preventing a fully out-of-tree
> build.  To fix this:
> 
> - Add $(OUTPUT) to their filenames in the relevant Makefile rules, and
>   create subdirectories as needed
> - Add $(OUTPUT)src to the include path
> - Add ${OUTPUT} to the BPF object filename in tests/timerlat.t
> 
> Fixes: e34293ddcebd ("rtla/timerlat: Add BPF skeleton to collect samples")
> Fixes: 0304a3b7ec9a ("rtla/timerlat: Add example for BPF action program")
> Fixes: 5525aebd4e0c ("rtla/tests: Test BPF action program")
> Signed-off-by: Ben Hutchings <benh@debian.org>

Hi Ben,

Can you send this as a separate patch. The rtla code is handled via a
different tree than the perf code. So these patches will not be going
together.

Thanks,

-- Steve

Re: [PATCH 1/3] rtla: Fix output files in source tree

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] `make clean` fails to remove the generated `$(OUTPUT)tests/bpf/bpf_action_map.o` file during out-of-tree builds.
--

commit ce6ce36bb0778cda3451364e21ac622e234e5df7
Author: Ben Hutchings <benh@debian.org>

rtla: Fix output files in source tree

This commit updates the rtla Makefile to place several generated BPF object
files and the skeleton header into the output directory to support fully
out-of-tree builds. It adds the $(OUTPUT) prefix to these files in the build
rules, tests, and the clean target.

> diff --git a/tools/tracing/rtla/Makefile b/tools/tracing/rtla/Makefile
> index 45690ee14544d..f54da7be735da 100644
> --- a/tools/tracing/rtla/Makefile
> +++ b/tools/tracing/rtla/Makefile
[ ... ]
> @@ -111,10 +118,10 @@ clean: doc_clean fixdep-clean
>  	$(Q)find . -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
>  	$(Q)rm -f rtla rtla-static fixdep FEATURE-DUMP rtla-*
>  	$(Q)rm -rf feature
> -	$(Q)rm -f src/timerlat.bpf.o src/timerlat.skel.h example/timerlat_bpf_action.o
> +	$(Q)rm -f $(OUTPUT)src/timerlat.bpf.o $(OUTPUT)src/timerlat.skel.h $(OUTPUT)example/timerlat_bpf_action.o

[Severity: Low]
Does this leave $(OUTPUT)tests/bpf/bpf_action_map.o behind after a clean?

Previously, tests/bpf/bpf_action_map.o was cleaned up by the find command on
the first line of this target. Now that it is placed in the $(OUTPUT) directory,
the find command might not reach it during an out-of-tree build, and it does
not appear to be included in this explicit rm command either.

>  	$(Q)rm -f $(UNIT_TESTS)

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/ag8X7gcDw6jpJsLq@decadent.org.uk?part=1

[PATCH 2/3] perf tools: Put Python egg info in output directory

[Ben Hutchings]

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Installing the Python extension currently creates an egg-info
directory in the source tree, preventing a fully out-of-tree build.

Add the necessary runes to the setup.py comamnd line to relocate the
egg-info directory in an out-of-tree build.

Signed-off-by: Ben Hutchings <benh@debian.org>
---
 tools/perf/Makefile.perf | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index cee19c923c06..899a4249a42f 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -1152,7 +1152,9 @@ install-bin: install-tools install-tests
 install: install-bin try-install-man
 
 install-python_ext:
-	$(PYTHON_WORD) util/setup.py --quiet install --root='/$(DESTDIR_SQ)'
+	$(PYTHON_WORD) util/setup.py --quiet \
+		$(if $(OUTPUT),egg_info --egg-base $(OUTPUT)) \
+		install --root='/$(DESTDIR_SQ)'
 
 # 'make install-doc' should call 'make -C Documentation install'
 $(INSTALL_DOC_TARGETS):


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[PATCH 3/3] perf tools: Put Python bytecode in output directory

[Ben Hutchings]

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The PMU events are processed into C sources by Python scripts, which
normally results in writing bytecode for each module into the source
tree.  This prevents a fully out-of-tree build.

To fix this, set $PYTHONPYCACHEPREFIX to relocate the bytecode cache
directory in an out-of-tree build.

Signed-off-by: Ben Hutchings <benh@debian.org>
---
 tools/perf/Makefile.perf | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 899a4249a42f..c35b65f9fdda 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -400,6 +400,11 @@ PYTHON_EXTBUILD_LIB := $(PYTHON_EXTBUILD)lib/
 PYTHON_EXTBUILD_TMP := $(PYTHON_EXTBUILD)tmp/
 export PYTHON_EXTBUILD_LIB PYTHON_EXTBUILD_TMP
 
+# Put Python bytecode in output directory
+ifdef OUTPUT
+export PYTHONPYCACHEPREFIX := $(OUTPUT)/__pycache__
+endif
+
 python-clean := $(call QUIET_CLEAN, python) $(RM) -r $(PYTHON_EXTBUILD) $(OUTPUT)python/perf*.so
 
 # Use the detected configuration

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Re: [PATCH 3/3] perf tools: Put Python bytecode in output directory

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] The use of `PYTHONPYCACHEPREFIX` fails to resolve out-of-tree build pollution for Python 3.6 and 3.7.
- [Low] The newly configured relocated Python bytecode cache directory (`$(OUTPUT)/__pycache__`) is not removed during `make clean` or `make python-clean`.
--

commit 7f6b9146d44a693c3114eaae7826841344f49ebd
Author: Ben Hutchings <benh@debian.org>

perf tools: Put Python bytecode in output directory

This commit sets PYTHONPYCACHEPREFIX during perf tool builds when an output
directory is specified. This aims to prevent Python from writing bytecode
into the source tree during out-of-tree builds.

> diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
> --- a/tools/perf/Makefile.perf
> +++ b/tools/perf/Makefile.perf
> @@ -399,6 +399,11 @@ PYTHON_EXTBUILD_LIB := $(PYTHON_EXTBUILD)lib/
>  PYTHON_EXTBUILD_TMP := $(PYTHON_EXTBUILD)tmp/
>  export PYTHON_EXTBUILD_LIB PYTHON_EXTBUILD_TMP
>  
> +# Put Python bytecode in output directory
> +ifdef OUTPUT
> +export PYTHONPYCACHEPREFIX := $(OUTPUT)/__pycache__

[Severity: Medium]
Since the perf build system explicitly supports Python 3.6 and 3.7, does
setting PYTHONPYCACHEPREFIX resolve the out-of-tree build pollution for
those versions?

This environment variable was introduced in Python 3.8 and is silently
ignored in earlier versions. Would exporting PYTHONDONTWRITEBYTECODE=1 be a
more universally supported alternative?

> +endif
> +
>  python-clean := $(call QUIET_CLEAN, python) $(RM) -r $(PYTHON_EXTBUILD) $(OUTPUT)python/perf*.so

[Severity: Low]
Does the newly configured relocated Python bytecode cache directory need to
be explicitly removed in the python-clean target?

The existing clean rules do not match the deep absolute paths created by
PYTHONPYCACHEPREFIX, which leaves the entire __pycache__ directory hierarchy
orphaned in the build output after a make clean.

>  # Use the detected configuration

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/ag8X7gcDw6jpJsLq@decadent.org.uk?part=3

Re: [PATCH 0/3] Fix out-of-tree build of some tools

[Ian Rogers]

On Thu, May 21, 2026 at 7:57 AM Ben Hutchings <benh@debian.org> wrote:
>
> perf and rtla currently don't fully support out-of-tree builds, as
> they may still create files in their source directory.  This series
> fixes all the instances of this problem that I have found.
>
> Ben.

Thanks for the cleanup! I ran Sashiko locally and it noted that we
should also fix the clean steps to remove these files (I'll copy the
full text below).
Reviewed-by: Ian Rogers <irogers@google.com>

```
commit cf212be834ce6b0df5cccdbc4ad977a917ff8e48
   Author: Ben Hutchings <benh@debian.org>

   perf tools: Put Python egg info in output directory

   Installing the Python extension currently creates an egg-info
   directory in the source tree, preventing a fully out-of-tree build.

   Add the necessary runes to the setup.py comamnd line to relocate the
   egg-info directory in an out-of-tree build.

   > diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
   > index fc92d6ceac5b..b9a9bdddb89a 100644
   > --- a/tools/perf/Makefile.perf
   > +++ b/tools/perf/Makefile.perf
   > @@ -905,7 +910,9 @@ install-bin: install-tools install-tests
   >  install: install-bin try-install-man
   >
   >  install-python_ext:
   > -       $(PYTHON_WORD) util/setup.py --quiet install
--root='/$(DESTDIR_SQ)'
   > +       $(PYTHON_WORD) util/setup.py --quiet \
   > +               $(if $(OUTPUT),egg_info --egg-base $(OUTPUT)) \
   > +               install --root='/$(DESTDIR_SQ)'

   This relocates the egg-info directory to the output directory, which
   helps keep the source tree clean. However, does the `python-clean`
   target need to be updated to clean up this directory?

   Currently, `python-clean` is defined as:

   python-clean := $(call QUIET_CLEAN, python) $(RM) -r
$(PYTHON_EXTBUILD) $(OUTPUT)python/perf*.so

   Should we also clean `$(OUTPUT)/perf.egg-info` (or `perf.egg-info` for
   in-tree builds) to ensure `make clean` removes all generated python
   metadata? For example:

   python-clean := $(call QUIET_CLEAN, python) \
                   $(RM) -r $(PYTHON_EXTBUILD) $(OUTPUT)python/perf*.so \
                   $(OUTPUT)perf.egg-info perf.egg-info

   commit dd754ea75966ec7ade41500afeb32d944f20a8f9
   Author: Ben Hutchings <benh@debian.org>

   perf tools: Put Python bytecode in output directory

   The PMU events are processed into C sources by Python scripts,
which
   normally results in writing bytecode for each module into the
source
   tree.  This prevents a fully out-of-tree build.

   To fix this, set $PYTHONPYCACHEPREFIX to relocate the bytecode cache
   directory in an out-of-tree build.

   > diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
   > index fc92d6ceac5b..b9a9bdddb89a 100644
   > --- a/tools/perf/Makefile.perf
   > +++ b/tools/perf/Makefile.perf
   > @@ -400,6 +400,11 @@ PYTHON_EXTBUILD_LIB :=
$(PYTHON_EXTBUILD)lib/
   >  PYTHON_EXTBUILD_TMP := $(PYTHON_EXTBUILD)tmp/
   >  export PYTHON_EXTBUILD_LIB PYTHON_EXTBUILD_TMP
   >
   > +# Put Python bytecode in output directory
   > +ifdef OUTPUT
   > +export PYTHONPYCACHEPREFIX := $(OUTPUT)/__pycache__
   > +endif
   > +
   >  python-clean := $(call QUIET_CLEAN, python) $(RM) -r
$(PYTHON_EXTBUILD) $(OUTPUT)python/perf*.so

   Similar to the egg-info relocation, does `python-clean` need to
clean up
   the relocated `__pycache__` directory under `$(OUTPUT)`?

   If `PYTHONPYCACHEPREFIX` is exported to `$(OUTPUT)/__pycache__`, running
   `make clean` currently leaves this directory behind. Should we add it to
   the `RM` list in `python-clean`? For example:

   python-clean := $(call QUIET_CLEAN, python) \
                   $(RM) -r $(PYTHON_EXTBUILD)
$(OUTPUT)python/perf*.so \
                   $(if $(OUTPUT),$(OUTPUT)/__pycache__)
```

Thanks,
Ian

> Ben Hutchings (3):
>   rtla: Fix output files in source tree
>   perf tools: Put Python egg info in output directory
>   perf tools: Put Python bytecode in output directory
>
>  tools/perf/Makefile.perf            |  9 ++++++++-
>  tools/tracing/rtla/Makefile         | 31 ++++++++++++++++++-----------
>  tools/tracing/rtla/tests/timerlat.t |  4 ++--
>  3 files changed, 29 insertions(+), 15 deletions(-)
>