kbuild: use relative path more to include Makefile

Prior to this commit, it was impossible to use relative path to
include Makefiles from the top level Makefile because the option
"--include-dir=$(srctree)" becomes effective when Make enters into
sub Makefiles.

To use relative path in any places, this commit moves the option
above the "sub-make" target.

Signed-off-by: Masahiro Yamada <[e-mail]>
Signed-off-by: Michal Marek <[e-mail]>

Makefile

···
 # Comments in this file are targeted only to the developer, do not
 # expect to learn how to build the kernel reading this file.
 
-# Do not use make's built-in rules and variables
-# (this increases performance and avoids hard-to-debug behaviour);
-MAKEFLAGS += -rR
+# o Do not use make's built-in rules and variables
+#   (this increases performance and avoids hard-to-debug behaviour);
+# o Look for make include files relative to root of kernel src
+MAKEFLAGS += -rR --include-dir=$(CURDIR)
 
 # Avoid funny character set dependencies
 unexport LC_ALL
···
 export COMPILER
 endif
 
-# Look for make include files relative to root of kernel src
-MAKEFLAGS += --include-dir=$(srctree)
-
 # We need some generic definitions (do not try to remake the file).
-$(srctree)/scripts/Kbuild.include: ;
-include $(srctree)/scripts/Kbuild.include
+scripts/Kbuild.include: ;
+include scripts/Kbuild.include
 
 # Make variables (CC, etc...)
 AS		= $(CROSS_COMPILE)as
···
 # Read arch specific Makefile to set KBUILD_DEFCONFIG as needed.
 # KBUILD_DEFCONFIG may point out an alternative default configuration
 # used for 'make defconfig'
-include $(srctree)/arch/$(SRCARCH)/Makefile
+include arch/$(SRCARCH)/Makefile
 export KBUILD_DEFCONFIG KBUILD_KCONFIG
 
 config: scripts_basic outputmakefile FORCE
···
 # Defaults to vmlinux, but the arch makefile usually adds further targets
 all: vmlinux
 
-include $(srctree)/arch/$(SRCARCH)/Makefile
+include arch/$(SRCARCH)/Makefile
 
 KBUILD_CFLAGS	+= $(call cc-option,-fno-delete-null-pointer-checks,)
 
···
 	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
 endif
 
-include $(srctree)/scripts/Makefile.kasan
-include $(srctree)/scripts/Makefile.extrawarn
+include scripts/Makefile.kasan
+include scripts/Makefile.extrawarn
 
 # Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
 KBUILD_CPPFLAGS += $(KCPPFLAGS)

arch/mips/Makefile

···
 #
 # Board-dependent options and extra files
 #
-include $(srctree)/arch/mips/Kbuild.platforms
+include arch/mips/Kbuild.platforms
 
 ifdef CONFIG_PHYSICAL_START
 load-y					= $(CONFIG_PHYSICAL_START)

arch/um/Makefile

···
 
 HOST_DIR := arch/$(HEADER_ARCH)
 
-include $(srctree)/$(ARCH_DIR)/Makefile-skas
-include $(srctree)/$(HOST_DIR)/Makefile.um
+include $(ARCH_DIR)/Makefile-skas
+include $(HOST_DIR)/Makefile.um
 
 core-y += $(HOST_DIR)/um/
 
···
 	$(filter -I%,$(CFLAGS)) -D_FILE_OFFSET_BITS=64 -idirafter include
 
 #This will adjust *FLAGS accordingly to the platform.
-include $(srctree)/$(ARCH_DIR)/Makefile-os-$(OS)
+include $(ARCH_DIR)/Makefile-os-$(OS)
 
 KBUILD_CPPFLAGS += -I$(srctree)/$(HOST_DIR)/include \
 		   -I$(srctree)/$(HOST_DIR)/include/uapi \

arch/x86/Makefile

···
 				$(call cc-option,-fno-unit-at-a-time))
 
         # CPU-specific tuning. Anything which can be shared with UML should go here.
-        include $(srctree)/arch/x86/Makefile_32.cpu
+        include arch/x86/Makefile_32.cpu
         KBUILD_CFLAGS += $(cflags-y)
 
         # temporary until string.h is fixed

arch/x86/Makefile.um

···
 export LDS_EXTRA
 
 # First of all, tune CFLAGS for the specific CPU. This actually sets cflags-y.
-include $(srctree)/arch/x86/Makefile_32.cpu
+include arch/x86/Makefile_32.cpu
 
 # prevent gcc from keeping the stack 16 byte aligned. Taken from i386.
 cflags-y += $(call cc-option,-mpreferred-stack-boundary=2)