+# Single targets
+# ---------------------------------------------------------------------------
+# To build individual files in subdirectories, you can do like this:
+#
+# make foo/bar/baz.s
+#
+# The supported suffixes for single-target are listed in 'single-targets'
+#
+# To build only under specific subdirectories, you can do like this:
+#
+# make foo/bar/baz/
+
+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-ko): single_modpost
+ @:
+$(single-no-ko): descend
+ @:
+
+ifeq ($(KBUILD_EXTMOD),)
+# For the single build of in-tree modules, use a temporary file to avoid
+# the situation of modules_install installing an invalid modules.order.
+MODORDER := .modules.tmp
+endif
+
+PHONY += single_modpost
+single_modpost: $(single-no-ko)
+ $(Q){ $(foreach m, $(single-ko), echo $(extmod-prefix)$m;) } > $(MODORDER)
+ $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
+
+KBUILD_MODULES := 1
+
+export KBUILD_SINGLE_TARGETS := $(addprefix $(extmod-prefix), $(single-no-ko))
+
+# trim unrelated directories
+build-dirs := $(foreach d, $(build-dirs), \
+ $(if $(filter $(d)/%, $(KBUILD_SINGLE_TARGETS)), $(d)))
+
+endif
+