Re: [PATCH 1/3] tools build: Add CFLAGS_REMOVE_* support

From: Arnaldo Carvalho de Melo
Date: Mon Nov 14 2016 - 09:37:24 EST


Em Wed, Nov 02, 2016 at 02:35:47PM +0100, Jiri Olsa escreveu:
> Adding support to remove options from final CFLAGS
> for both object file and build target. It's now
> possible to remove CFLAGS options like:
>
> CFLAGS_REMOVE_krava.o += -Wstrict-prototypes

That is cool, and I just looked and this comes from the kernel sources,
is there some place where the subset of such features that is supported
in tools/build is being documented?

Applying it, thanks.

- Arnaldo

> Link: http://lkml.kernel.org/n/tip-0t59dihg30fh035xo69df3m8@xxxxxxxxxxxxxx
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
> tools/build/Build.include | 4 +++-
> tools/build/Documentation/Build.txt | 6 ++++--
> 2 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/tools/build/Build.include b/tools/build/Build.include
> index 1dcb95e76f70..c4ae12a5d0a5 100644
> --- a/tools/build/Build.include
> +++ b/tools/build/Build.include
> @@ -89,7 +89,9 @@ if_changed = $(if $(strip $(any-prereq) $(arg-check)), \
> # - per target C flags
> # - per object C flags
> # - BUILD_STR macro to allow '-D"$(variable)"' constructs
> -c_flags = -Wp,-MD,$(depfile),-MT,$@ $(CFLAGS) -D"BUILD_STR(s)=\#s" $(CFLAGS_$(basetarget).o) $(CFLAGS_$(obj))
> +c_flags_1 = -Wp,-MD,$(depfile),-MT,$@ $(CFLAGS) -D"BUILD_STR(s)=\#s" $(CFLAGS_$(basetarget).o) $(CFLAGS_$(obj))
> +c_flags_2 = $(filter-out $(CFLAGS_REMOVE_$(basetarget).o), $(c_flags_1))
> +c_flags = $(filter-out $(CFLAGS_REMOVE_$(obj)), $(c_flags_2))
> cxx_flags = -Wp,-MD,$(depfile),-MT,$@ $(CXXFLAGS) -D"BUILD_STR(s)=\#s" $(CXXFLAGS_$(basetarget).o) $(CXXFLAGS_$(obj))
>
> ###
> diff --git a/tools/build/Documentation/Build.txt b/tools/build/Documentation/Build.txt
> index a47bffbae159..a22587475dbe 100644
> --- a/tools/build/Documentation/Build.txt
> +++ b/tools/build/Documentation/Build.txt
> @@ -135,8 +135,10 @@ CFLAGS
>
> It's possible to alter the standard object C flags in the following way:
>
> - CFLAGS_perf.o += '...' - alters CFLAGS for perf.o object
> - CFLAGS_gtk += '...' - alters CFLAGS for gtk build object
> + CFLAGS_perf.o += '...' - adds CFLAGS for perf.o object
> + CFLAGS_gtk += '...' - adds CFLAGS for gtk build object
> + CFLAGS_REMOVE_perf.o += '...' - removes CFLAGS for perf.o object
> + CFLAGS_REMOVE_gtk += '...' - removes CFLAGS for gtk build object
>
> This C flags changes has the scope of the Build makefile they are defined in.
>
> --
> 2.7.4