[v2,1/4] kbuild: do not create built-in.a that is never linked to vmlinux

Message ID 20190912162254.9603-1-yamada.masahiro@socionext.com
State New
Headers show
Series
  • [v2,1/4] kbuild: do not create built-in.a that is never linked to vmlinux
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Commit Message

Masahiro Yamada Sept. 12, 2019, 4:22 p.m.
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, useless orphan built-in.a
files are generated.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

---

Changes in v2: None

 scripts/Makefile.build | 2 +-
 scripts/Makefile.lib   | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

-- 
2.17.1

Patch

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index f72aba64d611..6c3e6cb0c0af 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 4a0cdd6f5909..26ac638525cb 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