perf tools jevents build flags (was Re: [PATCH] perf jevents: Fix sys_event_tables to be freed like arch_std_events)

[John Garry <john.garry@huawei.com>]

On 28/09/2021 21:30, John Garry wrote:
>>>
>>> OK, would you also consider reusing CFLAGS:
>>>
>>> --- a/tools/perf/pmu-events/Build
>>> +++ b/tools/perf/pmu-events/Build
>>> @@ -9,10 +9,12 @@ JSON          =  $(shell [ -d $(JDIR) ] &&
>>> \
>>> JDIR_TEST      =  pmu-events/arch/test
>>> JSON_TEST      =  $(shell [ -d $(JDIR_TEST) ] &&                       \
>>>                         find $(JDIR_TEST) -name '*.json')
>>> -
>>> +HOSTCFLAGS_jevents += $(CFLAGS)
>> Humm, we have to check if CFLAGS doesn't come with cross-build options,
>> i.e. IIRC we have to use HOSTCFLAGS instead. Unsure if there is some
>> *CFLAGS variable that gets the common part, where these -Wall and
>> -Wextra, -Werror could go.
> 
> not sure. As I see, the bulk of flags we have in CFLAGS comes from 
> EXTRA_WARNINGS in scripts/Makefile.include; but CFLAGS seems to also 
> include EXTRA_CLAGS, which are for cross-builds (see perf/Makefile.config)
> 

Hi Arnaldo,

I'm just looking at enabling warning cflags for jevents again.

So how about this:

--->8----


Subject: [PATCH] perf pmu-events: Enable jevents warnings through HOSTCFLAGS


diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 0ae2e3d8b832..65934984f032 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -17,6 +17,7 @@ detected     = $(shell echo "$(1)=y"       >> 
$(OUTPUT).config-detected)
  detected_var = $(shell echo "$(1)=$($(1))" >> $(OUTPUT).config-detected)

  CFLAGS := $(EXTRA_CFLAGS) $(filter-out -Wnested-externs,$(EXTRA_WARNINGS))
+HOSTCFLAGS := $(filter-out -Wnested-externs,$(EXTRA_WARNINGS))

  include $(srctree)/tools/scripts/Makefile.arch

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 7df13e74450c..118bcdc70bb4 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -226,7 +226,7 @@ else
  endif

  export srctree OUTPUT RM CC CXX LD AR CFLAGS CXXFLAGS V BISON FLEX AWK
-export HOSTCC HOSTLD HOSTAR
+export HOSTCC HOSTLD HOSTAR HOSTCFLAGS

  include $(srctree)/tools/build/Makefile.include

diff --git a/tools/perf/pmu-events/Build b/tools/perf/pmu-events/Build
index a055dee6a46a..d5c287f069a2 100644
--- a/tools/perf/pmu-events/Build
+++ b/tools/perf/pmu-events/Build
@@ -1,7 +1,7 @@
  hostprogs := jevents

  jevents-y	+= json.o jsmn.o jevents.o
-HOSTCFLAGS_jevents.o	= -I$(srctree)/tools/include
+HOSTCFLAGS_jevents.o	= -I$(srctree)/tools/include $(HOSTCFLAGS)
  pmu-events-y	+= pmu-events.o
  JDIR		=  pmu-events/arch/$(SRCARCH)
  JSON		=  $(shell [ -d $(JDIR) ] &&				\
-- 
2.26.2

---8<---

The newly generated warnings in jevents.c are pretty straightforward to 
tidy up.

Thanks,
John