[PATCH 1/3] kbuild: remove obj and src from the top Makefile

[PATCH 1/3] kbuild: remove obj and src from the top Makefile

[Masahiro Yamada]

$(obj) is not used in the top Makefile at all. $(src) is used in
3 sites, but they can be replaced with $(srctree).

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

 Makefile | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index 014390e32b0e..a5615edf2196 100644
--- a/Makefile
+++ b/Makefile
@@ -248,9 +248,6 @@ endif
 export KBUILD_CHECKSRC KBUILD_EXTMOD KBUILD_SRC
 
 objtree		:= .
-src		:= $(srctree)
-obj		:= $(objtree)
-
 VPATH		:= $(srctree)
 
 export srctree objtree VPATH
@@ -1705,7 +1702,7 @@ CHECKSTACK_ARCH := $(ARCH)
 endif
 checkstack:
 	$(OBJDUMP) -d vmlinux $$(find . -name '*.ko') | \
-	$(PERL) $(src)/scripts/checkstack.pl $(CHECKSTACK_ARCH)
+	$(PERL) $(srctree)/scripts/checkstack.pl $(CHECKSTACK_ARCH)
 
 kernelrelease:
 	@echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"
@@ -1724,11 +1721,11 @@ endif
 
 tools/: FORCE
 	$(Q)mkdir -p $(objtree)/tools
-	$(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(tools_silent) $(filter --j% -j,$(MAKEFLAGS))" O=$(abspath $(objtree)) subdir=tools -C $(src)/tools/
+	$(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(tools_silent) $(filter --j% -j,$(MAKEFLAGS))" O=$(abspath $(objtree)) subdir=tools -C $(srctree)/tools/
 
 tools/%: FORCE
 	$(Q)mkdir -p $(objtree)/tools
-	$(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(tools_silent) $(filter --j% -j,$(MAKEFLAGS))" O=$(abspath $(objtree)) subdir=tools -C $(src)/tools/ $*
+	$(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(tools_silent) $(filter --j% -j,$(MAKEFLAGS))" O=$(abspath $(objtree)) subdir=tools -C $(srctree)/tools/ $*
 
 # Single targets
 # ---------------------------------------------------------------------------
-- 
2.17.1

[PATCH 2/3] kbuild: replace KBUILD_SRCTREE with boolean building_out_of_srctree

[Masahiro Yamada]

Commit 25b146c5b8ce ("kbuild: allow Kbuild to start from any directory")
deprecated KBUILD_SRCTREE.

It is only used in tools/testing/selftest/ to distinguish out-of-tree
build. Replace it with a new boolean flag, building_out_of_srctree.

I also replaced the conditional ($(srctree),.) because the next commit
will allow an absolute path for $(srctree) even when building in the
source tree.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

 Makefile                         | 19 ++++++++-----------
 scripts/Makefile.build           |  2 +-
 scripts/Makefile.host            |  2 +-
 scripts/Makefile.lib             |  2 +-
 scripts/Makefile.modbuiltin      |  2 +-
 scripts/gdb/linux/Makefile       |  2 +-
 tools/testing/selftests/Makefile |  2 +-
 tools/testing/selftests/lib.mk   |  4 ++--
 8 files changed, 16 insertions(+), 19 deletions(-)

diff --git a/Makefile b/Makefile
index a5615edf2196..534a5dc796b1 100644
--- a/Makefile
+++ b/Makefile
@@ -228,9 +228,12 @@ ifeq ("$(origin M)", "command line")
   KBUILD_EXTMOD := $(M)
 endif
 
+export KBUILD_CHECKSRC KBUILD_EXTMOD
+
 ifeq ($(abs_srctree),$(abs_objtree))
         # building in the source tree
         srctree := .
+	building_out_of_srctree :=
 else
         ifeq ($(abs_srctree)/,$(dir $(abs_objtree)))
                 # building in a subdirectory of the source tree
@@ -238,19 +241,13 @@ else
         else
                 srctree := $(abs_srctree)
         endif
-
-	# TODO:
-	# KBUILD_SRC is only used to distinguish in-tree/out-of-tree build.
-	# Replace it with $(srctree) or something.
-	KBUILD_SRC := $(abs_srctree)
+	building_out_of_srctree := 1
 endif
 
-export KBUILD_CHECKSRC KBUILD_EXTMOD KBUILD_SRC
-
 objtree		:= .
 VPATH		:= $(srctree)
 
-export srctree objtree VPATH
+export building_out_of_srctree srctree objtree VPATH
 
 # To make sure we do not include .config for any of the *config targets
 # catch them early, and hand them over to scripts/kconfig/Makefile
@@ -453,7 +450,7 @@ USERINCLUDE    := \
 LINUXINCLUDE    := \
 		-I$(srctree)/arch/$(SRCARCH)/include \
 		-I$(objtree)/arch/$(SRCARCH)/include/generated \
-		$(if $(filter .,$(srctree)),,-I$(srctree)/include) \
+		$(if $(building_out_of_srctree),-I$(srctree)/include) \
 		-I$(objtree)/include \
 		$(USERINCLUDE)
 
@@ -509,7 +506,7 @@ PHONY += outputmakefile
 # At the same time when output Makefile generated, generate .gitignore to
 # ignore whole output directory
 outputmakefile:
-ifneq ($(srctree),.)
+ifdef building_out_of_srctree
 	$(Q)ln -fsn $(srctree) source
 	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile $(srctree)
 	$(Q)test -e .gitignore || \
@@ -1093,7 +1090,7 @@ PHONY += prepare archprepare prepare1 prepare3
 # and if so do:
 # 1) Check that make has not been executed in the kernel src $(srctree)
 prepare3: include/config/kernel.release
-ifneq ($(srctree),.)
+ifdef building_out_of_srctree
 	@$(kecho) '  Using $(srctree) as source for kernel'
 	$(Q)if [ -f $(srctree)/.config -o \
 		 -d $(srctree)/include/config -o \
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 341fca59d28f..1086caaac786 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -509,7 +509,7 @@ existing-targets := $(wildcard $(sort $(targets)))
 
 -include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
 
-ifneq ($(srctree),.)
+ifdef building_out_of_srctree
 # Create directories for object files if they do not exist
 obj-dirs := $(sort $(obj) $(patsubst %/,%, $(dir $(targets))))
 # If targets exist, their directories apparently exist. Skip mkdir.
diff --git a/scripts/Makefile.host b/scripts/Makefile.host
index b6a54bdf0965..fcf0213e6ac8 100644
--- a/scripts/Makefile.host
+++ b/scripts/Makefile.host
@@ -69,7 +69,7 @@ _hostcxx_flags = $(KBUILD_HOSTCXXFLAGS) $(HOST_EXTRACXXFLAGS) \
 
 # $(objtree)/$(obj) for including generated headers from checkin source files
 ifeq ($(KBUILD_EXTMOD),)
-ifneq ($(srctree),.)
+ifdef building_out_of_srctree
 _hostc_flags   += -I $(objtree)/$(obj)
 _hostcxx_flags += -I $(objtree)/$(obj)
 endif
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 4d006923763c..f835a40ebae5 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -148,7 +148,7 @@ endif
 # $(srctree)/$(src) for including checkin headers from generated source files
 # $(objtree)/$(obj) for including generated headers from checkin source files
 ifeq ($(KBUILD_EXTMOD),)
-ifneq ($(srctree),.)
+ifdef building_out_of_srctree
 _c_flags   += -I $(srctree)/$(src) -I $(objtree)/$(obj)
 _a_flags   += -I $(srctree)/$(src) -I $(objtree)/$(obj)
 _cpp_flags += -I $(srctree)/$(src) -I $(objtree)/$(obj)
diff --git a/scripts/Makefile.modbuiltin b/scripts/Makefile.modbuiltin
index 12ac300fe51b..7d4711b88656 100644
--- a/scripts/Makefile.modbuiltin
+++ b/scripts/Makefile.modbuiltin
@@ -15,7 +15,7 @@ include include/config/tristate.conf
 
 include scripts/Kbuild.include
 
-ifneq ($(srctree),.)
+ifdef building_out_of_srctree
 # Create output directory if not already present
 _dummy := $(shell [ -d $(obj) ] || mkdir -p $(obj))
 endif
diff --git a/scripts/gdb/linux/Makefile b/scripts/gdb/linux/Makefile
index 9fd3d8ed731a..124755087510 100644
--- a/scripts/gdb/linux/Makefile
+++ b/scripts/gdb/linux/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
-ifneq ($(srctree),.)
+ifdef building_out_of_srctree
 
 symlinks := $(patsubst $(srctree)/$(src)/%,%,$(wildcard $(srctree)/$(src)/*.py))
 
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 9781ca79794a..25b43a8c2b15 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -74,7 +74,7 @@ endif
 # Append kselftest to KBUILD_OUTPUT to avoid cluttering
 # KBUILD_OUTPUT with selftest objects and headers installed
 # by selftests Makefile or lib.mk.
-ifneq ($(KBUILD_SRC),)
+ifdef building_out_of_srctree
 override LDFLAGS =
 endif
 
diff --git a/tools/testing/selftests/lib.mk b/tools/testing/selftests/lib.mk
index 077337195783..1c8a1963d03f 100644
--- a/tools/testing/selftests/lib.mk
+++ b/tools/testing/selftests/lib.mk
@@ -70,7 +70,7 @@ define RUN_TESTS
 endef
 
 run_tests: all
-ifneq ($(KBUILD_SRC),)
+ifdef building_out_of_srctree
 	@if [ "X$(TEST_PROGS) $(TEST_PROGS_EXTENDED) $(TEST_FILES)" != "X" ]; then
 		@rsync -aq $(TEST_PROGS) $(TEST_PROGS_EXTENDED) $(TEST_FILES) $(OUTPUT)
 	fi
@@ -125,7 +125,7 @@ clean:
 # When make O= with kselftest target from main level
 # the following aren't defined.
 #
-ifneq ($(KBUILD_SRC),)
+ifdef building_out_of_srctree
 LINK.c = $(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) $(TARGET_ARCH)
 COMPILE.S = $(CC) $(ASFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c
 LINK.S = $(CC) $(ASFLAGS) $(CPPFLAGS) $(LDFLAGS) $(TARGET_ARCH)
-- 
2.17.1

[PATCH 3/3] kbuild: add a flag to force absolute path for srctree

[Masahiro Yamada]

In old days, Kbuild always used an absolute path for $(srctree).

Since commit 890676c65d69 ("kbuild: Use relative path when building in
the source tree"), $(srctree) is '.' when not using O=.

Yet, using absolute paths is useful in some cases even without O=, for
instance, to create a cscope file with absolute path tags.

O=. was used as an idiom to force Kbuild to use absolute paths even
when you are building in the source tree.

Since commit 25b146c5b8ce ("kbuild: allow Kbuild to start from any
directory"), Kbuild is too clever to be tricked. Even if you pass O=.
Kbuild notices you are building in the source tree, then use '.' for
$(srctree).

So, "make O=. cscope" is no help to create absolute path tags.

We cannot force one or the other according to commit e93bc1a0cab3
("Revert "kbuild: specify absolute paths for cscope""). Both of
relative path and absolute path have pros and cons.

This commit adds a new flag KBUILD_ABS_SRCTREE to allow users to
choose the absolute path for $(srctree).

"make KBUILD_ABS_SRCTREE=1 cscope" will work as a replacement of
"make O=. cscope".

I added Fixes since that commit broke some users' workflow.

Fixes: 25b146c5b8ce ("kbuild: allow Kbuild to start from any directory")
Reported-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

 Documentation/kbuild/kbuild.txt | 9 +++++++++
 Makefile                        | 4 ++++
 scripts/tags.sh                 | 3 +--
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index 7a7e2aa2fab5..3ef42f87f275 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -182,6 +182,15 @@ The output directory is often set using "O=..." on the commandline.
 
 The value can be overridden in which case the default value is ignored.
 
+KBUILD_ABS_SRCTREE
+--------------------------------------------------
+Kbuild uses a relative path to point to the tree when possible. For instance,
+when building in the source tree, the source tree path is '.'
+
+Setting this flag requests Kbuild to use absolute path to the source tree.
+There are some useful cases to do so, like when generating tag files with
+absolute path entries etc.
+
 KBUILD_SIGN_PIN
 --------------------------------------------------
 This variable allows a passphrase or PIN to be passed to the sign-file
diff --git a/Makefile b/Makefile
index 534a5dc796b1..6dc453f86f00 100644
--- a/Makefile
+++ b/Makefile
@@ -244,6 +244,10 @@ else
 	building_out_of_srctree := 1
 endif
 
+ifneq ($(KBUILD_ABS_SRCTREE),)
+srctree := $(abs_srctree)
+endif
+
 objtree		:= .
 VPATH		:= $(srctree)
 
diff --git a/scripts/tags.sh b/scripts/tags.sh
index 7fea4044749b..4e18ae5282a6 100755
--- a/scripts/tags.sh
+++ b/scripts/tags.sh
@@ -17,8 +17,7 @@ ignore="$(echo "$RCS_FIND_IGNORE" | sed 's|\\||g' )"
 # tags and cscope files should also ignore MODVERSION *.mod.c files
 ignore="$ignore ( -name *.mod.c ) -prune -o"
 
-# Do not use full path if we do not use O=.. builds
-# Use make O=. {tags|cscope}
+# Use make KBUILD_ABS_SRCTREE=1 {tags|cscope}
 # to force full paths for a non-O= build
 if [ "${srctree}" = "." -o -z "${srctree}" ]; then
 	tree=
-- 
2.17.1