kbuild: skip sub-make for in-tree build with GNU Make 4.x

[people/arne_f/kernel.git] / Makefile

diff --git a/Makefile b/Makefile
index d11a0df90c7320c2911358db621ea995218ebb0f..956d2acb17aa75399fc26a67b08559f51358db6f 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -31,16 +31,6 @@ _all:
 # descending is started. They are now explicitly listed as the
 # prepare rule.
 
-# Ugly workaround for Debian make-kpkg:
-# make-kpkg directly includes the top Makefile of Linux kernel. In such a case,
-# skip sub-make to support debian_* targets in ruleset/kernel_version.mk, but
-# displays warning to discourage such abusage.
-ifneq ($(word 2, $(MAKEFILE_LIST)),)
-$(warning Do not include top Makefile of Linux Kernel)
-sub-make-done := 1
-MAKEFLAGS += -rR
-endif
-
 ifneq ($(sub-make-done),1)
 
 # Do not use make's built-in rules and variables
@@ -153,6 +143,7 @@ $(if $(KBUILD_OUTPUT),, \
 # 'sub-make' below.
 MAKEFLAGS += --include-dir=$(CURDIR)
 
+need-sub-make := 1
 else
 
 # Do not print "Entering directory ..." at all for in-tree build.
@@ -160,6 +151,16 @@ MAKEFLAGS += --no-print-directory
 
 endif # ifneq ($(KBUILD_OUTPUT),)
 
+ifneq ($(filter 3.%,$(MAKE_VERSION)),)
+# 'MAKEFLAGS += -rR' does not immediately become effective for GNU Make 3.x
+# We need to invoke sub-make to avoid implicit rules in the top Makefile.
+need-sub-make := 1
+# Cancel implicit rules for this Makefile.
+$(lastword $(MAKEFILE_LIST)): ;
+endif
+
+ifeq ($(need-sub-make),1)
+
 PHONY += $(MAKECMDGOALS) sub-make
 
 $(filter-out _all sub-make $(CURDIR)/Makefile, $(MAKECMDGOALS)) _all: sub-make
@@ -171,8 +172,11 @@ sub-make:
        $(if $(KBUILD_OUTPUT),-C $(KBUILD_OUTPUT) KBUILD_SRC=$(CURDIR)) \
        -f $(CURDIR)/Makefile $(filter-out _all sub-make,$(MAKECMDGOALS))
 
-else # sub-make-done
+endif # need-sub-make
+endif # sub-make-done
+
 # We process the rest of the Makefile if this is the final invocation of make
+ifeq ($(need-sub-make),)
 
 # Do not print "Entering directory ...",
 # but we want to display it when entering to the output directory
@@ -1773,7 +1777,7 @@ $(cmd_files): ;   # Do not try to update included dependency files
 
 endif   # ifeq ($(config-targets),1)
 endif   # ifeq ($(mixed-targets),1)
-endif   # sub-make-done
+endif   # need-sub-make
 
 PHONY += FORCE
 FORCE: