linux-kernel - [PATCH 6/7] kbuild: make *.mod not depend on *.o

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Date:   Thu,  7 Apr 2022 00:30:22 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     linux-kbuild@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: [PATCH 6/7] kbuild: make *.mod not depend on *.o

The dependency

    $(obj)/%.mod: $(obj)/%$(mod-prelink-ext).o

... exists because *.mod files previously contained undefined symbols,
which are computed from *.o files when CONFIG_TRIM_UNUSED_KSYMS=y.

Now that the undefined symbols are put into separate *.usyms files,
there is no reason to make *.mod depend on *.o files.

Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
---

 Makefile               | 3 ++-
 scripts/Makefile.build | 5 ++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index 82ee893909e9..e915aacd02b0 100644
--- a/Makefile
+++ b/Makefile
@@ -1792,7 +1792,8 @@ ifdef single-build
 
 # .ko is special because modpost is needed
 single-ko := $(sort $(filter %.ko, $(MAKECMDGOALS)))
-single-no-ko := $(sort $(patsubst %.ko,%.mod, $(MAKECMDGOALS)))
+single-no-ko := $(filter-out $(single-ko), $(MAKECMDGOALS)) \
+		$(foreach x, o mod, $(patsubst %.ko, %.$x, $(single-ko)))
 
 $(single-ko): single_modpost
 	@:
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index f7a30f378e20..3da731cf6978 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -85,7 +85,7 @@ ifdef need-builtin
 targets-for-builtin += $(obj)/built-in.a
 endif
 
-targets-for-modules := $(foreach x, mod $(if $(CONFIG_TRIM_UNUSED_KSYMS), usyms), \
+targets-for-modules := $(foreach x, o mod $(if $(CONFIG_TRIM_UNUSED_KSYMS), usyms), \
 				$(patsubst %.o, %.$x, $(filter %.o, $(obj-m))))
 
 ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)
@@ -306,7 +306,7 @@ endif
 cmd_mod = echo $(addprefix $(obj)/, $(call real-search, $*.o, .o, -objs -y -m)) | \
 	$(AWK) -v RS='( |\n)' '!x[$$0]++' > $@
 
-$(obj)/%.mod: $(obj)/%$(mod-prelink-ext).o FORCE
+$(obj)/%.mod: FORCE
 	$(call if_changed,mod)
 
 # List module undefined symbols
@@ -469,7 +469,6 @@ $(multi-obj-m): FORCE
 	$(call if_changed,link_multi-m)
 $(call multi_depend, $(multi-obj-m), .o, -objs -y -m)
 
-targets += $(multi-obj-m)
 targets := $(filter-out $(PHONY), $(targets))
 
 # Add intermediate targets:
-- 
2.32.0