Re: [PATCH v2 2/2] perf jevents: Enable warnings through HOSTCFLAGS

[Arnaldo Carvalho de Melo]

Em Mon, Oct 25, 2021 at 01:40:44PM +0200, Jiri Olsa escreveu:
> On Fri, Oct 22, 2021 at 10:42:11AM +0100, John Garry wrote:
> > On 21/10/2021 13:48, Jiri Olsa wrote:
> > > > +HOSTCFLAGS += -Wall
> > > > +HOSTCFLAGS += -Wextra
> > > > +
> > > >   # Enforce a non-executable stack, as we may regress (again) in the future by
> > > >   # adding assembler files missing the .GNU-stack linker note.
> > > >   LDFLAGS += -Wl,-z,noexecstack
> > > > 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 $(HOSTCFLAGS)
> > > so the the host cflags are made of:
> > > 
> > > host_c_flags = -Wp,-MD,$(depfile) -Wp,-MT,$@ $(KBUILD_HOSTCFLAGS) -D"BUILD_STR(s)=\#s" $(HOSTCFLAGS_$(basetarget).o) $(HOSTCFLAGS_$(obj))
> > > 
> > 
> > ok, so IIRC, then the rule for building .o from .c in
> > tools/build/Makefile.build will pick up HOSTCFLAGS through this variable, so
> > we then don't need to explicitly mention it in the per-target rule, so can
> > have this as before in pmu-events/Build
> > 
> > HOSTCFLAGS_jevents.o	= -I$(srctree)/tools/include
> > 
> > right?
> > 
> > (Indeed I guess that we can get rid of -I$(srctree)/tools/include as well)
> 
> hm, the -I.. should stay no? I don't see that
> it's being added soem other way
> 
> jirka
> 

Probably this change from KBUILD_HOSTCFLAGS back to HOSTCFLAGS should
come with this;

Cc: Laura Abbott <labbott@xxxxxxxxxx>
Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Fixes: 96f14fe738b69dd9 ("kbuild: Rename HOSTCFLAGS to KBUILD_HOSTCFLAGS")

Right?

- Arnaldo
 
> ---
> diff --git a/tools/build/Build.include b/tools/build/Build.include
> index 2cf3b1bde86e..c2a95ab47379 100644
> --- a/tools/build/Build.include
> +++ b/tools/build/Build.include
> @@ -99,7 +99,7 @@ cxx_flags = -Wp,-MD,$(depfile) -Wp,-MT,$@ $(CXXFLAGS) -D"BUILD_STR(s)=\#s" $(CXX
>  ###
>  ## HOSTCC C flags
>  
> -host_c_flags = -Wp,-MD,$(depfile) -Wp,-MT,$@ $(KBUILD_HOSTCFLAGS) -D"BUILD_STR(s)=\#s" $(HOSTCFLAGS_$(basetarget).o) $(HOSTCFLAGS_$(obj))
> +host_c_flags = -Wp,-MD,$(depfile) -Wp,-MT,$@ $(HOSTCFLAGS) -D"BUILD_STR(s)=\#s" $(HOSTCFLAGS_$(basetarget).o) $(HOSTCFLAGS_$(obj))
>  
>  # output directory for tests below
>  TMPOUT = .tmp_$$$$
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index 0ae2e3d8b832..374f65b52157 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 $(srctree)/tools/scripts/Makefile.arch
>  
> @@ -211,6 +212,7 @@ endif
>  ifneq ($(WERROR),0)
>    CORE_CFLAGS += -Werror
>    CXXFLAGS += -Werror
> +  HOSTCFLAGS += -Werror
>  endif
>  
>  ifndef DEBUG
> @@ -292,6 +294,9 @@ CXXFLAGS += -ggdb3
>  CXXFLAGS += -funwind-tables
>  CXXFLAGS += -Wno-strict-aliasing
>  
> +HOSTCFLAGS += -Wall
> +HOSTCFLAGS += -Wextra
> +
>  # Enforce a non-executable stack, as we may regress (again) in the future by
>  # adding assembler files missing the .GNU-stack linker note.
>  LDFLAGS += -Wl,-z,noexecstack
> 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
>  

-- 

- Arnaldo