Re: [PATCH v4 05/30] bpftool: Avoid adding EXTRA_CFLAGS to HOST_CFLAGS

[Leo Yan]

On Thu, Mar 12, 2026 at 10:19:01AM -0700, Ian Rogers wrote:
> On Wed, Mar 11, 2026 at 1:30 AM Leo Yan <leo.yan@xxxxxxx> wrote:
> >
> > Prepare for future changes where EXTRA_CFLAGS may include flags not
> > applicable to the host compiler.
> >
> > Move the HOST_CFLAGS assignment before appending EXTRA_CFLAGS to
> > CFLAGS so that HOST_CFLAGS does not inherit flags from EXTRA_CFLAGS.
> >
> > Acked-by: Quentin Monnet <qmo@xxxxxxxxxx>
> > Signed-off-by: Leo Yan <leo.yan@xxxxxxx>
> > ---
> >  tools/bpf/bpftool/Makefile | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
> > index 519ea5cb8ab1c0ee31acc67fc5f96b40e21005c2..3e7d8359e1b2a81a29a47544be8539e3b191a0e8 100644
> > --- a/tools/bpf/bpftool/Makefile
> > +++ b/tools/bpf/bpftool/Makefile
> > @@ -81,6 +81,12 @@ CFLAGS += -DPACKAGE='"bpftool"' -D__EXPORTED_HEADERS__ \
> >  ifneq ($(BPFTOOL_VERSION),)
> >  CFLAGS += -DBPFTOOL_VERSION='"$(BPFTOOL_VERSION)"'
> >  endif
> > +
> > +# This must be done before appending EXTRA_CFLAGS to CFLAGS to avoid
> > +# including flags that are not applicable to the host compiler.
> > +HOST_CFLAGS := $(subst -I$(LIBBPF_INCLUDE),-I$(LIBBPF_BOOTSTRAP_INCLUDE),\
> > +               $(subst $(CLANG_CROSS_FLAGS),,$(CFLAGS)))
> > +
> >  ifneq ($(EXTRA_CFLAGS),)
> >  CFLAGS += $(EXTRA_CFLAGS)
> >  endif
> > @@ -88,8 +94,6 @@ ifneq ($(EXTRA_LDFLAGS),)
> >  LDFLAGS += $(EXTRA_LDFLAGS)
> >  endif
> >
> > -HOST_CFLAGS := $(subst -I$(LIBBPF_INCLUDE),-I$(LIBBPF_BOOTSTRAP_INCLUDE),\
> > -               $(subst $(CLANG_CROSS_FLAGS),,$(CFLAGS)))
> >  HOST_LDFLAGS := $(LDFLAGS)
> 
> Should HOST_LDFLAGS be similarly moved? Otherwise, it seems target
> flags in EXTRA_LDFLAGS will be added for the host.

Though this series is irrelevant to LDFLAGS, I am fine to move
HOST_LDFLAGS together.

Quentin, how about you think?