Hi Arnaldo,
On Thu, Jul 27, 2023 at 4:31 AM Arnaldo Carvalho de Melo acme@kernel.org wrote:
Em Wed, Jul 26, 2023 at 11:45:44PM -0700, Namhyung Kim escreveu:
On Wed, Jul 26, 2023 at 9:48 PM Ian Rogers irogers@google.com wrote:
On Wed, Jul 26, 2023 at 6:01 PM Namhyung Kim namhyung@kernel.org wrote:
On Wed, Jul 26, 2023 at 5:36 PM Ian Rogers irogers@google.com wrote:
On Wed, Jul 26, 2023 at 3:57 PM Namhyung Kim namhyung@kernel.org wrote:
On Wed, Jul 26, 2023 at 8:48 AM Ian Rogers irogers@google.com wrote: > On Wed, Jul 26, 2023 at 6:36 AM Namhyung Kim namhyung@kernel.org wrote: > > The bison and flex generate C files from the source (.y and .l) > > files. When O= option is used, they are saved in a separate directory > > but the default build rule assumes the .C files are in the source > > directory. So it might read invalid file if there are generated files > > from an old version. The same is true for the pmu-events files. > > > > For example, the following command would cause a build failure: > > > > $ git checkout v6.3 > > $ make -C tools/perf # build in the same directory > > > > $ git checkout v6.5-rc2 > > $ mkdir build # create a build directory > > $ make -C tools/perf O=build # build in a different directory but it > > # refers files in the source directory > > > > Let's update the build rule to specify those cases explicitly to depend > > on the files in the output directory. > > > > Note that it's not a complete fix and it needs the next patch for the > > include path too. > > > > Fixes: 80eeb67fe577 ("perf jevents: Program to convert JSON file") > > Cc: stable@vger.kernel.org > > Signed-off-by: Namhyung Kim namhyung@kernel.org > > --- > > tools/build/Makefile.build | 8 ++++++++ > > tools/perf/pmu-events/Build | 4 ++++ > > 2 files changed, 12 insertions(+) > > > > diff --git a/tools/build/Makefile.build b/tools/build/Makefile.build > > index 89430338a3d9..f9396696fcbf 100644 > > --- a/tools/build/Makefile.build > > +++ b/tools/build/Makefile.build > > @@ -117,6 +117,14 @@ $(OUTPUT)%.s: %.c FORCE > > $(call rule_mkdir) > > $(call if_changed_dep,cc_s_c) > > > > +$(OUTPUT)%-bison.o: $(OUTPUT)%-bison.c FORCE > > + $(call rule_mkdir) > > + $(call if_changed_dep,$(host)cc_o_c) > > + > > +$(OUTPUT)%-flex.o: $(OUTPUT)%-flex.c FORCE > > + $(call rule_mkdir) > > + $(call if_changed_dep,$(host)cc_o_c) > > + > > Hi Namhyung, > > as we have: > ``` > $(OUTPUT)%.o: %.c FORCE > $(call rule_mkdir) > $(call if_changed_dep,$(host)cc_o_c) > ``` > I'm not sure what the 2 additional rules achieve.
The above rule assumes the .c files are in the source directory (without $(OUTPUT) prefix). It caused a trouble when the flex and bison files are generated in the output directory and you have an old version of them in the source directory.
> > # Gather build data: > > # obj-y - list of build objects > > # subdir-y - list of directories to nest > > diff --git a/tools/perf/pmu-events/Build b/tools/perf/pmu-events/Build > > index 150765f2baee..f38a27765604 100644 > > --- a/tools/perf/pmu-events/Build > > +++ b/tools/perf/pmu-events/Build > > @@ -35,3 +35,7 @@ $(PMU_EVENTS_C): $(JSON) $(JSON_TEST) $(JEVENTS_PY) $(METRIC_PY) $(METRIC_TEST_L > > $(call rule_mkdir) > > $(Q)$(call echo-cmd,gen)$(PYTHON) $(JEVENTS_PY) $(JEVENTS_ARCH) $(JEVENTS_MODEL) pmu-events/arch $@ > > endif > > + > > +$(OUTPUT)pmu-events/pmu-events.o: $(PMU_EVENTS_C) > > + $(call rule_mkdir) > > + $(call if_changed_dep,$(host)cc_o_c) > > If we add this, do the Makefile.build changes still need to happen?
The Makefile.build changes are specific to flex and bison files. So yes, we need this for pmu-events.c to work properly with O= option.
Got it, you are right I was confusing the flex/bison with the jevents case. Can we get away with a single rule then:
$(OUTPUT)%.o: $(OUTPUT)%.c FORCE $(call rule_mkdir) $(call if_changed_dep,$(host)cc_o_c)Probably, but I wonder if it affects the normal .c files expecting them in the OUTPUT directory.
Hmm.. I think the longer matches may be necessary to trigger the "more specific" ordering: https://www.gnu.org/software/make/manual/html_node/Pattern-Match.html
I'm not keen on these extra rules that mirror existing rules, it is a bit cryptic what is going on. I wonder if it would be cleaner just to fail the build if the bogus pmu-events.c exists. For example:
I prefer just making it build instead of failing. But not strongly against your idea. It'd be nice to hear what others think.. Arnaldo?
I think that we should just ignore any build files in the source tree when using 'O=', i.e.:
make -C tools/perf
genereated files (in the source tree) should not be used when, right after running it, we run:
make -C tools/perf O=/some/build/dir
If we run 'make -C tools/perf' and there is a pmu-events.c, use it if its timestamp is more recent than the files from which it was generated, as usual for a make managed build.
Right, this is what my patch does by adding specific rules for generated files. I'll add a comment to describe why it's needed.
Thanks, Namhyung