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@xxxxxxxxxxxxx> --- 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
