kbuild: skip sub-make for in-tree build with GNU Make 4.x
Commit 2b50f7ab6368 ("kbuild: add workaround for Debian make-kpkg")
annoyed people who want to wrap the top Makefile with GNUmakefile
to customize it for their use.
On second thought, we do not need to run the sub-make for in-tree
build with Make 4.x because the 'MAKEFLAGS += -rR' issue only happens
on GNU Make 3.x.
With this commit, people will get back their workflow, and the Debian
make-kpkg will still work.
Fixes: 2b50f7ab6368 ("kbuild: add workaround for Debian make-kpkg")
Reported-by: Andreas Schwab <schwab@suse.de>
Reported-by: David Howells <dhowells@redhat.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: Andreas Schwab <schwab@suse.de>
Tested-by: David Howells <dhowells@redhat.com>
diff --git a/Makefile b/Makefile
index 8c6acfd..6c0635f 100644
--- a/Makefile
+++ b/Makefile
@@ -31,26 +31,12 @@
# 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 ($(sub-make-done),1)
# Do not use make's built-in rules and variables
# (this increases performance and avoids hard-to-debug behaviour)
MAKEFLAGS += -rR
-# 'MAKEFLAGS += -rR' does not become immediately effective for old
-# GNU Make versions. Cancel implicit rules for this Makefile.
-$(lastword $(MAKEFILE_LIST)): ;
-
# Avoid funny character set dependencies
unexport LC_ALL
LC_COLLATE=C
@@ -153,6 +139,7 @@
# 'sub-make' below.
MAKEFLAGS += --include-dir=$(CURDIR)
+need-sub-make := 1
else
# Do not print "Entering directory ..." at all for in-tree build.
@@ -160,6 +147,16 @@
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 +168,11 @@
$(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 ($(need-sub-make),)
# Do not print "Entering directory ...",
# but we want to display it when entering to the output directory
@@ -1757,7 +1757,7 @@
endif # ifeq ($(config-targets),1)
endif # ifeq ($(mixed-targets),1)
-endif # sub-make-done
+endif # need-sub-make
PHONY += FORCE
FORCE: