Re: [bpf-next PATCH v2 4/4] kbuild: refactor module BTF rule

Andrii Nakryiko
2023-10-19T22:55:32Z

On Thu, Oct 19, 2023 at 1:15 AM Jiri Olsa <olsajiri@gmail.com> wrote:
>
> On Thu, Oct 19, 2023 at 12:19:50AM +0900, Masahiro Yamada wrote:
> > newer_prereqs_except and if_changed_except are ugly hacks of the
> > newer-prereqs and if_changed in scripts/Kbuild.include.
> >
> > Remove.
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> > ---
> >
> > Changes in v2:
> > - Fix if_changed_except to if_changed
> >
> > scripts/Makefile.modfinal | 25 ++++++-------------------
> > 1 file changed, 6 insertions(+), 19 deletions(-)
> >
> > diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
> > index 9fd7a26e4fe9..fc07854bb7b9 100644
> > --- a/scripts/Makefile.modfinal
> > +++ b/scripts/Makefile.modfinal
> > @@ -19,6 +19,9 @@ vmlinux :=
> > ifdef CONFIG_DEBUG_INFO_BTF_MODULES
> > ifneq ($(wildcard vmlinux),)
> > vmlinux := vmlinux
> > +cmd_btf = ; \
> > + LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) --btf_base vmlinux $@; \
> > + $(RESOLVE_BTFIDS) -b vmlinux $@
> > else
> > $(warning Skipping BTF generation due to unavailability of vmlinux)
> > endif
> > @@ -41,27 +44,11 @@ quiet_cmd_ld_ko_o = LD [M] $@
> > cmd_ld_ko_o += \
> > $(LD) -r $(KBUILD_LDFLAGS) \
> > $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
> > - -T scripts/module.lds -o $@ $(filter %.o, $^)
> > + -T scripts/module.lds -o $@ $(filter %.o, $^) \
> > + $(cmd_btf)
> >
> > -quiet_cmd_btf_ko = BTF [M] $@
>
> nit not sure it's intentional but we no longer display 'BTF [M] ...ko' lines,
> I don't mind not displaying that, but we should mention that in changelog
>

Thanks for spotting this! I think those messages are useful and
important to keep. Masahiro, is it possible to preserve them?

> jirka
>
> > - cmd_btf_ko = \
> > - LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) --btf_base vmlinux $@; \
> > - $(RESOLVE_BTFIDS) -b vmlinux $@
> > -
> > -# Same as newer-prereqs, but allows to exclude specified extra dependencies
> > -newer_prereqs_except = $(filter-out $(PHONY) $(1),$?)
> > -
> > -# Same as if_changed, but allows to exclude specified extra dependencies
> > -if_changed_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check), \
> > - $(cmd); \
> > - printf '%s\n' 'savedcmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
> > -
> > -# Re-generate module BTFs if either module's .ko or vmlinux changed
> > %.ko: %.o %.mod.o scripts/module.lds $(vmlinux) FORCE
> > - +$(call if_changed_except,ld_ko_o,vmlinux)
> > -ifdef vmlinux
> > - +$(if $(newer-prereqs),$(call cmd,btf_ko))
> > -endif
> > + +$(call if_changed,ld_ko_o)
> >
> > targets += $(modules:%.o=%.ko) $(modules:%.o=%.mod.o)
> >
> > --
> > 2.40.1
> >
> >
>