* [PATCH 1/3] kbuild: do not create built-in.a that is never linked to vmlinux
@ 2019-09-12 7:33 Masahiro Yamada
2019-09-12 7:33 ` [PATCH 2/3] kbuild: warn orphan obj-y objects Masahiro Yamada
2019-09-12 7:33 ` [PATCH 3/3] kbuild: change need-modorder implementation slightly Masahiro Yamada
0 siblings, 2 replies; 3+ messages in thread
From: Masahiro Yamada @ 2019-09-12 7:33 UTC (permalink / raw)
To: linux-kbuild; +Cc: Masahiro Yamada, Michal Marek, linux-kernel
Both 'obj-y += foo/' and 'obj-m += foo/' requrest Kbuild to visit the
sub-directory foo/, but the difference is that only the former combines
foo/built-in.a into the built-in.a of the current directory because
everything in sub-directories visited by obj-m is supposed to be modular.
So, it makes sense to create built-in.a only if that sub-directory is
reachable by the chain of obj-y. Otherwise, built-in.a will not be
linked into vmlinux anyway. If an orphan built-in.a is created, it is
very likely a Makefile bug.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---
scripts/Makefile.build | 2 +-
scripts/Makefile.lib | 4 ++++
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 9fa09361aa5d..54fc68168686 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -66,7 +66,7 @@ lib-target := $(obj)/lib.a
real-obj-y += $(obj)/lib-ksyms.o
endif
-ifneq ($(strip $(real-obj-y) $(need-builtin)),)
+ifdef need-builtin
builtin-target := $(obj)/built-in.a
endif
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 264611972c4a..07095d3789a1 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -35,7 +35,11 @@ __subdir-y := $(patsubst %/,%,$(filter %/, $(obj-y)))
subdir-y += $(__subdir-y)
__subdir-m := $(patsubst %/,%,$(filter %/, $(obj-m)))
subdir-m += $(__subdir-m)
+ifdef need-builtin
obj-y := $(patsubst %/, %/built-in.a, $(obj-y))
+else
+obj-y := $(filter-out %/, $(obj-y))
+endif
obj-m := $(filter-out %/, $(obj-m))
# Subdirectories we need to descend into
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 2/3] kbuild: warn orphan obj-y objects
2019-09-12 7:33 [PATCH 1/3] kbuild: do not create built-in.a that is never linked to vmlinux Masahiro Yamada
@ 2019-09-12 7:33 ` Masahiro Yamada
2019-09-12 7:33 ` [PATCH 3/3] kbuild: change need-modorder implementation slightly Masahiro Yamada
1 sibling, 0 replies; 3+ messages in thread
From: Masahiro Yamada @ 2019-09-12 7:33 UTC (permalink / raw)
To: linux-kbuild; +Cc: Masahiro Yamada, Michal Marek, linux-kernel
obj-y specifies objects linked into vmlinux, but they are actually
linked if and only if that sub-directory is visited by the chain of
obj-y. If you have an orphan obj-y object, it is a bug, but may not
easy to notice. This commit provides build-time warning.
I tested allmodconfig based on v5.3-rc4, and I saw one warning:
scripts/Makefile.build:57: 'sound/soc/sprd/sprd-mcdt.o' will not be linked to vmlinux even though obj-y is specified.
This is a proper warning. sound/soc/sprd/sprd-mcdt.o is compiled as
built-in since CONFIG_SND_SOC_SPRD_MCDT is boolean. However, CONFIG_SND
and CONFIG_SND_SOC are tristate, and set to m by allmodconfig.
So, Kbuild descends into sound/soc/, then sound/soc/sprd/ by obj-m.
sound/soc/sprd/sprd-mcdt.o is not linked to vmlinux.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---
scripts/Makefile.build | 6 ++++++
scripts/link-vmlinux.sh | 2 +-
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 54fc68168686..d30b04707fec 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -52,6 +52,12 @@ ifndef obj
$(warning kbuild: Makefile.build is included improperly)
endif
+ifeq ($(need-builtin),)
+ifneq ($(real-obj-y),)
+$(warning '$(real-obj-y)' will not be linked to vmlinux even though obj-y is specified.)
+endif
+endif
+
ifeq ($(need-modorder),)
ifneq ($(obj-m),)
$(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.)
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 2438a9faf3f1..8961d999b86b 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -216,7 +216,7 @@ else
fi;
# final build of init/
-${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
+${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
#link vmlinux.o
info LD vmlinux.o
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH 3/3] kbuild: change need-modorder implementation slightly
2019-09-12 7:33 [PATCH 1/3] kbuild: do not create built-in.a that is never linked to vmlinux Masahiro Yamada
2019-09-12 7:33 ` [PATCH 2/3] kbuild: warn orphan obj-y objects Masahiro Yamada
@ 2019-09-12 7:33 ` Masahiro Yamada
1 sibling, 0 replies; 3+ messages in thread
From: Masahiro Yamada @ 2019-09-12 7:33 UTC (permalink / raw)
To: linux-kbuild; +Cc: Masahiro Yamada, Michal Marek, linux-kernel
Align with the need-builtin implementation.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---
scripts/Makefile.build | 2 +-
scripts/Makefile.lib | 2 ++
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index d30b04707fec..91617b9d7a34 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -528,7 +528,7 @@ $(subdir-ym):
$(Q)$(MAKE) $(build)=$@ \
$(if $(filter $@/, $(KBUILD_SINGLE_TARGETS)),single-build=) \
need-builtin=$(if $(filter $@/built-in.a, $(subdir-obj-y)),1) \
- need-modorder=$(if $(need-modorder),$(if $(filter $@/modules.order, $(modorder)),1))
+ need-modorder=$(if $(filter $@/modules.order, $(modorder)),1)
# Add FORCE to the prequisites of a target to force it to be always rebuilt.
# ---------------------------------------------------------------------------
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 07095d3789a1..034e92ea72c6 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -23,7 +23,9 @@ lib-y := $(filter-out $(obj-y), $(sort $(lib-y) $(lib-m)))
# Determine modorder.
# Unfortunately, we don't have information about ordering between -y
# and -m subdirs. Just put -y's first.
+ifdef need-modorder
modorder := $(patsubst %/,%/modules.order, $(filter %/, $(obj-y)) $(obj-m:.o=.ko))
+endif
# Handle objects in subdirs
# ---------------------------------------------------------------------------
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
end of thread, other threads:[~2019-09-12 7:33 UTC | newest]
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2019-09-12 7:33 ` [PATCH 3/3] kbuild: change need-modorder implementation slightly Masahiro Yamada
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