Merge tag 'kbuild-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:

 - do not generate unneeded top-level built-in.a

 - let git ignore O= directory entirely

 - optimize scripts/kallsyms slightly

 - exclude DWARF info from *.s regardless of config options

 - fix GCC toolchain search path for Clang to prepare ld.lld support

 - do not generate modules.order when CONFIG_MODULES is disabled

 - simplify single target rules and remove VPATH for external module
   build

 - allow to add optional flags to dpkg-buildpackage when building
   deb-pkg

 - move some compiler option tests from Makefile to Kconfig

 - various Makefile cleanups

* tag 'kbuild-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (40 commits)
  kbuild: remove scripts/basic/% build target
  kbuild: use -Werror=implicit-... instead of -Werror-implicit-...
  kbuild: clean up scripts/gcc-version.sh
  kbuild: remove cc-version macro
  kbuild: update comment block of scripts/clang-version.sh
  kbuild: remove commented-out INITRD_COMPRESS
  kbuild: move -gsplit-dwarf, -gdwarf-4 option tests to Kconfig
  kbuild: [bin]deb-pkg: add DPKG_FLAGS variable
  kbuild: move ".config not found!" message from Kconfig to Makefile
  kbuild: invoke syncconfig if include/config/auto.conf.cmd is missing
  kbuild: simplify single target rules
  kbuild: remove empty rules for makefiles
  kbuild: make -r/-R effective in top Makefile for old Make versions
  kbuild: move tools_silent to a more relevant place
  kbuild: compute false-positive -Wmaybe-uninitialized cases in Kconfig
  kbuild: refactor cc-cross-prefix implementation
  kbuild: hardcode genksyms path and remove GENKSYMS variable
  scripts/gdb: refactor rules for symlink creation
  kbuild: create symlink to vmlinux-gdb.py in scripts_gdb target
  scripts/gdb: do not descend into scripts/gdb from scripts
  ...

Documentation/devicetree/bindings/Makefile

@@ -15,7 +15,7 @@ DT_TMP_SCHEMA := processed-schema.yaml
 extra-y += $(DT_TMP_SCHEMA)
 
 quiet_cmd_mk_schema = SCHEMA  $@
-      cmd_mk_schema = $(DT_MK_SCHEMA) $(DT_MK_SCHEMA_FLAGS) -o $@ $(filter-out FORCE, $^)
+      cmd_mk_schema = $(DT_MK_SCHEMA) $(DT_MK_SCHEMA_FLAGS) -o $@ $(real-prereqs)
 
 DT_DOCS = $(shell \
 	cd $(srctree)/$(src) && \

Documentation/kbuild/kbuild.txt

@@ -232,17 +232,12 @@ KBUILD_LDS
 --------------------------------------------------
 The linker script with full path. Assigned by the top-level Makefile.
 
-KBUILD_VMLINUX_INIT
+KBUILD_VMLINUX_OBJS
 --------------------------------------------------
-All object files for the init (first) part of vmlinux.
-Files specified with KBUILD_VMLINUX_INIT are linked first.
-
-KBUILD_VMLINUX_MAIN
---------------------------------------------------
-All object files for the main part of vmlinux.
+All object files for vmlinux. They are linked to vmlinux in the same
+order as listed in KBUILD_VMLINUX_OBJS.
 
 KBUILD_VMLINUX_LIBS
 --------------------------------------------------
-All .a "lib" files for vmlinux.
-KBUILD_VMLINUX_INIT, KBUILD_VMLINUX_MAIN, and KBUILD_VMLINUX_LIBS together
-specify all the object files used to link vmlinux.
+All .a "lib" files for vmlinux. KBUILD_VMLINUX_OBJS and KBUILD_VMLINUX_LIBS
+together specify all the object files used to link vmlinux.

Documentation/kbuild/makefiles.txt

@@ -154,13 +154,8 @@ more details, with real examples.
 
 	Kbuild compiles all the $(obj-y) files.  It then calls
 	"$(AR) rcSTP" to merge these files into one built-in.a file.
-	This is a thin archive without a symbol table, which makes it
-	unsuitable as a linker input.
-
-	The scripts/link-vmlinux.sh script later makes an aggregate
-	built-in.a with "${AR} rcsTP", which creates the thin archive
-	with a symbol table and an index, making it a valid input for
-	the final vmlinux link passes.
+	This is a thin archive without a symbol table. It will be later
+	linked into vmlinux by scripts/link-vmlinux.sh
 
 	The order of files in $(obj-y) is significant.  Duplicates in
 	the lists are allowed: the first instance will be linked into
@@ -504,23 +499,6 @@ more details, with real examples.
 	In the above example, -Wno-unused-but-set-variable will be added to
 	KBUILD_CFLAGS only if gcc really accepts it.
 
-    cc-version
-	cc-version returns a numerical version of the $(CC) compiler version.
-	The format is <major><minor> where both are two digits. So for example
-	gcc 3.41 would return 0341.
-	cc-version is useful when a specific $(CC) version is faulty in one
-	area, for example -mregparm=3 was broken in some gcc versions
-	even though the option was accepted by gcc.
-
-	Example:
-		#arch/x86/Makefile
-		cflags-y += $(shell \
-		if [ $(cc-version) -ge 0300 ] ; then \
-			echo "-mregparm=3"; fi ;)
-
-	In the above example, -mregparm=3 is only used for gcc version greater
-	than or equal to gcc 3.0.
-
     cc-ifversion
 	cc-ifversion tests the version of $(CC) and equals the fourth parameter
 	if version expression is true, or the fifth (if given) if the version

Documentation/kbuild/modules.txt

@@ -140,7 +140,7 @@ executed to make module versioning work.
 		make -C $KDIR M=$PWD bar.lst
 		make -C $KDIR M=$PWD baz.o
 		make -C $KDIR M=$PWD foo.ko
-		make -C $KDIR M=$PWD /
+		make -C $KDIR M=$PWD ./
 
 
 === 3. Creating a Kbuild File for an External Module

Kbuild

 # SPDX-License-Identifier: GPL-2.0
 #
 # Kbuild for top-level directory of the kernel
-# This file takes care of the following:
-# 1) Generate bounds.h
-# 2) Generate timeconst.h
-# 3) Generate asm-offsets.h (may need bounds.h and timeconst.h)
-# 4) Check for missing system calls
-# 5) check atomics headers are up-to-date
-# 6) Generate constants.py (may need bounds.h)
 
 #####
-# 1) Generate bounds.h
+# Generate bounds.h
 
 bounds-file := include/generated/bounds.h
 
@@ -21,7 +14,7 @@ $(bounds-file): kernel/bounds.s FORCE
 	$(call filechk,offsets,__LINUX_BOUNDS_H__)
 
 #####
-# 2) Generate timeconst.h
+# Generate timeconst.h
 
 timeconst-file := include/generated/timeconst.h
 
@@ -33,8 +26,7 @@ $(timeconst-file): kernel/time/timeconst.bc FORCE
 	$(call filechk,gentimeconst)
 
 #####
-# 3) Generate asm-offsets.h
-#
+# Generate asm-offsets.h
 
 offsets-file := include/generated/asm-offsets.h
 
@@ -47,8 +39,7 @@ $(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s FORCE
 	$(call filechk,offsets,__ASM_OFFSETS_H__)
 
 #####
-# 4) Check for missing system calls
-#
+# Check for missing system calls
 
 always += missing-syscalls
 targets += missing-syscalls
@@ -60,8 +51,7 @@ missing-syscalls: scripts/checksyscalls.sh $(offsets-file) FORCE
 	$(call cmd,syscalls)
 
 #####
-# 5) Check atomic headers are up-to-date
-#
+# Check atomic headers are up-to-date
 
 always += old-atomics
 targets += old-atomics
@@ -72,14 +62,5 @@ quiet_cmd_atomics = CALL    $<
 old-atomics: scripts/atomic/check-atomics.sh FORCE
 	$(call cmd,atomics)
 
-#####
-# 6) Generate constants for Python GDB integration
-#
-
-extra-$(CONFIG_GDB_SCRIPTS) += build_constants_py
-
-build_constants_py: $(timeconst-file) $(bounds-file)
-	@$(MAKE) $(build)=scripts/gdb/linux $@
-
 # Keep these three files during make clean
 no-clean-files := $(bounds-file) $(offsets-file) $(timeconst-file)

Makefile

@@ -15,19 +15,6 @@ NAME = Shy Crocodile
 PHONY := _all
 _all:
 
-# Do not use make's built-in rules and variables
-# (this increases performance and avoids hard-to-debug behaviour)
-MAKEFLAGS += -rR
-
-# Avoid funny character set dependencies
-unexport LC_ALL
-LC_COLLATE=C
-LC_NUMERIC=C
-export LC_COLLATE LC_NUMERIC
-
-# Avoid interference with shell env settings
-unexport GREP_OPTIONS
-
 # We are using a recursive build, so we need to do a little thinking
 # to get the ordering right.
 #
@@ -44,6 +31,25 @@ unexport GREP_OPTIONS
 # descending is started. They are now explicitly listed as the
 # prepare rule.
 
+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
+LC_NUMERIC=C
+export LC_COLLATE LC_NUMERIC
+
+# Avoid interference with shell env settings
+unexport GREP_OPTIONS
+
 # Beautify output
 # ---------------------------------------------------------------------------
 #
@@ -90,7 +96,6 @@ endif
 
 ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)
   quiet=silent_
-  tools_silent=s
 endif
 
 export quiet Q KBUILD_VERBOSE
@@ -112,7 +117,6 @@ export quiet Q KBUILD_VERBOSE
 
 # KBUILD_SRC is not intended to be used by the regular user (for now),
 # it is set on invocation of make with KBUILD_OUTPUT or O= specified.
-ifeq ($(KBUILD_SRC),)
 
 # OK, Make called in directory where kernel src resides
 # Do we want to locate output files in a separate directory?
@@ -120,9 +124,6 @@ ifeq ("$(origin O)", "command line")
   KBUILD_OUTPUT := $(O)
 endif
 
-# Cancel implicit rules on top Makefile
-$(CURDIR)/Makefile Makefile: ;
-
 ifneq ($(words $(subst :, ,$(CURDIR))), 1)
   $(error main directory cannot contain spaces nor colons)
 endif
@@ -142,6 +143,13 @@ $(if $(KBUILD_OUTPUT),, \
 # 'sub-make' below.
 MAKEFLAGS += --include-dir=$(CURDIR)
 
+else
+
+# Do not print "Entering directory ..." at all for in-tree build.
+MAKEFLAGS += --no-print-directory
+
+endif # ifneq ($(KBUILD_OUTPUT),)
+
 PHONY += $(MAKECMDGOALS) sub-make
 
 $(filter-out _all sub-make $(CURDIR)/Makefile, $(MAKECMDGOALS)) _all: sub-make
@@ -149,16 +157,12 @@ $(filter-out _all sub-make $(CURDIR)/Makefile, $(MAKECMDGOALS)) _all: sub-make
 
 # Invoke a second make in the output directory, passing relevant variables
 sub-make:
-	$(Q)$(MAKE) -C $(KBUILD_OUTPUT) KBUILD_SRC=$(CURDIR) \
+	$(Q)$(MAKE) sub-make-done=1 \
+	$(if $(KBUILD_OUTPUT),-C $(KBUILD_OUTPUT) KBUILD_SRC=$(CURDIR)) \
 	-f $(CURDIR)/Makefile $(filter-out _all sub-make,$(MAKECMDGOALS))
 
-# Leave processing to above invocation of make
-skip-makefile := 1
-endif # ifneq ($(KBUILD_OUTPUT),)
-endif # ifeq ($(KBUILD_SRC),)
-
+else # sub-make-done
 # We process the rest of the Makefile if this is the final invocation of make
-ifeq ($(skip-makefile),)
 
 # Do not print "Entering directory ...",
 # but we want to display it when entering to the output directory
@@ -215,7 +219,7 @@ objtree		:= .
 src		:= $(srctree)
 obj		:= $(objtree)
 
-VPATH		:= $(srctree)$(if $(KBUILD_EXTMOD),:$(KBUILD_EXTMOD))
+VPATH		:= $(srctree)
 
 export srctree objtree VPATH
 
@@ -300,8 +304,6 @@ __build_one_by_one:
 
 else
 
-# We need some generic definitions (do not try to remake the file).
-scripts/Kbuild.include: ;
 include scripts/Kbuild.include
 
 # Read KERNELRELEASE from include/config/kernel.release (if it exists)
@@ -390,7 +392,6 @@ OBJDUMP		= $(CROSS_COMPILE)objdump
 LEX		= flex
 YACC		= bison
 AWK		= awk
-GENKSYMS	= scripts/genksyms/genksyms
 INSTALLKERNEL  := installkernel
 DEPMOD		= /sbin/depmod
 PERL		= perl
@@ -429,7 +430,7 @@ LINUXINCLUDE    := \
 KBUILD_AFLAGS   := -D__ASSEMBLY__ -fno-PIE
 KBUILD_CFLAGS   := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \
 		   -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE \
-		   -Werror-implicit-function-declaration -Werror=implicit-int \
+		   -Werror=implicit-function-declaration -Werror=implicit-int \
 		   -Wno-format-security \
 		   -std=gnu89
 KBUILD_CPPFLAGS := -D__KERNEL__
@@ -443,7 +444,7 @@ GCC_PLUGINS_CFLAGS :=
 
 export ARCH SRCARCH CONFIG_SHELL HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE AS LD CC
 export CPP AR NM STRIP OBJCOPY OBJDUMP KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS
-export MAKE LEX YACC AWK GENKSYMS INSTALLKERNEL PERL PYTHON PYTHON2 PYTHON3 UTS_MACHINE
+export MAKE LEX YACC AWK INSTALLKERNEL PERL PYTHON PYTHON2 PYTHON3 UTS_MACHINE
 export HOSTCXX KBUILD_HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
 
 export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS KBUILD_LDFLAGS
@@ -476,23 +477,23 @@ scripts_basic:
 	$(Q)$(MAKE) $(build)=scripts/basic
 	$(Q)rm -f .tmp_quiet_recordmcount
 
-# To avoid any implicit rule to kick in, define an empty command.
-scripts/basic/%: scripts_basic ;
-
 PHONY += outputmakefile
 # outputmakefile generates a Makefile in the output directory, if using a
 # separate output directory. This allows convenient use of make in the
 # output directory.
+# At the same time when output Makefile generated, generate .gitignore to
+# ignore whole output directory
 outputmakefile:
 ifneq ($(KBUILD_SRC),)
 	$(Q)ln -fsn $(srctree) source
 	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile $(srctree)
+	$(Q){ echo "# this is build directory, ignore it"; echo "*"; } > .gitignore
 endif
 
 ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
 ifneq ($(CROSS_COMPILE),)
 CLANG_FLAGS	:= --target=$(notdir $(CROSS_COMPILE:%-=%))
-GCC_TOOLCHAIN_DIR := $(dir $(shell which $(LD)))
+GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))
 CLANG_FLAGS	+= --prefix=$(GCC_TOOLCHAIN_DIR)
 GCC_TOOLCHAIN	:= $(realpath $(GCC_TOOLCHAIN_DIR)/..)
 endif
@@ -624,13 +625,22 @@ ifeq ($(may-sync-config),1)
 # because some architectures define CROSS_COMPILE there.
 -include include/config/auto.conf.cmd
 
-# To avoid any implicit rule to kick in, define an empty command
-$(KCONFIG_CONFIG) include/config/auto.conf.cmd: ;
+$(KCONFIG_CONFIG):
+	@echo >&2 '***'
+	@echo >&2 '*** Configuration file "$@" not found!'
+	@echo >&2 '***'
+	@echo >&2 '*** Please run some configurator (e.g. "make oldconfig" or'
+	@echo >&2 '*** "make menuconfig" or "make xconfig").'
+	@echo >&2 '***'
+	@/bin/false
 
 # The actual configuration files used during the build are stored in
 # include/generated/ and include/config/. Update them if .config is newer than
 # include/config/auto.conf (which mirrors .config).
-include/config/%.conf: $(KCONFIG_CONFIG) include/config/auto.conf.cmd
+#
+# This exploits the 'multi-target pattern rule' trick.
+# The syncconfig should be executed only once to make all the targets.
+%/auto.conf %/auto.conf.cmd %/tristate.conf: $(KCONFIG_CONFIG)
 	$(Q)$(MAKE) -f $(srctree)/Makefile syncconfig
 else
 # External modules and some install targets need include/generated/autoconf.h
@@ -658,17 +668,13 @@ KBUILD_CFLAGS	+= $(call cc-disable-warning, int-in-bool-context)
 
 ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
 KBUILD_CFLAGS	+= $(call cc-option,-Oz,-Os)
-KBUILD_CFLAGS	+= $(call cc-disable-warning,maybe-uninitialized,)
-else
-ifdef CONFIG_PROFILE_ALL_BRANCHES
-KBUILD_CFLAGS	+= -O2 $(call cc-disable-warning,maybe-uninitialized,)
 else
 KBUILD_CFLAGS   += -O2
 endif
-endif
 
-KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0409, \
-			$(call cc-disable-warning,maybe-uninitialized,))
+ifdef CONFIG_CC_DISABLE_WARN_MAYBE_UNINITIALIZED
+KBUILD_CFLAGS   += -Wno-maybe-uninitialized
+endif
 
 # Tell gcc to never replace conditional load with a non-conditional one
 KBUILD_CFLAGS	+= $(call cc-option,--param=allow-store-data-races=0)
@@ -729,25 +735,28 @@ KBUILD_CFLAGS	+= -fomit-frame-pointer
 endif
 endif
 
-KBUILD_CFLAGS   += $(call cc-option, -fno-var-tracking-assignments)
+DEBUG_CFLAGS	:= $(call cc-option, -fno-var-tracking-assignments)
 
 ifdef CONFIG_DEBUG_INFO
 ifdef CONFIG_DEBUG_INFO_SPLIT
-KBUILD_CFLAGS   += $(call cc-option, -gsplit-dwarf, -g)
+DEBUG_CFLAGS	+= -gsplit-dwarf
 else
-KBUILD_CFLAGS	+= -g
+DEBUG_CFLAGS	+= -g
 endif
 KBUILD_AFLAGS	+= -Wa,-gdwarf-2
 endif
 ifdef CONFIG_DEBUG_INFO_DWARF4
-KBUILD_CFLAGS	+= $(call cc-option, -gdwarf-4,)
+DEBUG_CFLAGS	+= -gdwarf-4
 endif
 
 ifdef CONFIG_DEBUG_INFO_REDUCED
-KBUILD_CFLAGS 	+= $(call cc-option, -femit-struct-debug-baseonly) \
+DEBUG_CFLAGS	+= $(call cc-option, -femit-struct-debug-baseonly) \
 		   $(call cc-option,-fno-var-tracking)
 endif
 
+KBUILD_CFLAGS += $(DEBUG_CFLAGS)
+export DEBUG_CFLAGS
+
 ifdef CONFIG_FUNCTION_TRACER
 ifdef CONFIG_FTRACE_MCOUNT_RECORD
   # gcc 5 supports generating the mcount tables directly
@@ -922,19 +931,6 @@ ifdef CONFIG_MODULE_COMPRESS
 endif # CONFIG_MODULE_COMPRESS
 export mod_compress_cmd
 
-# Select initial ramdisk compression format, default is gzip(1).
-# This shall be used by the dracut(8) tool while creating an initramfs image.
-#
-INITRD_COMPRESS-y                  := gzip
-INITRD_COMPRESS-$(CONFIG_RD_BZIP2) := bzip2
-INITRD_COMPRESS-$(CONFIG_RD_LZMA)  := lzma
-INITRD_COMPRESS-$(CONFIG_RD_XZ)    := xz
-INITRD_COMPRESS-$(CONFIG_RD_LZO)   := lzo
-INITRD_COMPRESS-$(CONFIG_RD_LZ4)   := lz4
-# do not export INITRD_COMPRESS, since we didn't actually
-# choose a sane default compression above.
-# export INITRD_COMPRESS := $(INITRD_COMPRESS-y)
-
 ifdef CONFIG_MODULE_SIG_ALL
 $(eval $(call config_filename,MODULE_SIG_KEY))
 
@@ -976,15 +972,15 @@ libs-y2		:= $(patsubst %/, %/built-in.a, $(filter-out %.a, $(libs-y)))
 virt-y		:= $(patsubst %/, %/built-in.a, $(virt-y))
 
 # Externally visible symbols (used by link-vmlinux.sh)
-export KBUILD_VMLINUX_INIT := $(head-y) $(init-y)
-export KBUILD_VMLINUX_MAIN := $(core-y) $(libs-y2) $(drivers-y) $(net-y) $(virt-y)
+export KBUILD_VMLINUX_OBJS := $(head-y) $(init-y) $(core-y) $(libs-y2) \
+			      $(drivers-y) $(net-y) $(virt-y)
 export KBUILD_VMLINUX_LIBS := $(libs-y1)
 export KBUILD_LDS          := arch/$(SRCARCH)/kernel/vmlinux.lds
 export LDFLAGS_vmlinux
 # used by scripts/package/Makefile
 export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) arch Documentation include samples scripts tools)
 
-vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN) $(KBUILD_VMLINUX_LIBS)
+vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)
 
 # Recurse until adjust_autoksyms.sh is satisfied
 PHONY += autoksyms_recursive
@@ -1015,9 +1011,6 @@ cmd_link-vmlinux =                                                 \
 	$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
 
 vmlinux: scripts/link-vmlinux.sh autoksyms_recursive $(vmlinux-deps) FORCE
-ifdef CONFIG_GDB_SCRIPTS
-	$(Q)ln -fsn $(abspath $(srctree)/scripts/gdb/vmlinux-gdb.py)
-endif
 	+$(call if_changed,link-vmlinux)
 
 targets := vmlinux
@@ -1062,7 +1055,7 @@ scripts: scripts_basic scripts_dtc
 # archprepare is used in arch Makefiles and when processed asm symlink,
 # version.h and scripts_basic is processed / created.
 
-PHONY += prepare archprepare prepare1 prepare2 prepare3
+PHONY += prepare archprepare prepare1 prepare3
 
 # prepare3 is used to check if we are building in a separate output directory,
 # and if so do:
@@ -1077,12 +1070,8 @@ ifneq ($(KBUILD_SRC),)
 	fi;
 endif
 
-# prepare2 creates a makefile if using a separate output directory.
-# From this point forward, .config has been reprocessed, so any rules
-# that need to depend on updated CONFIG_* values can be checked here.
-prepare2: prepare3 outputmakefile asm-generic
-
-prepare1: prepare2 $(version_h) $(autoksyms_h) include/generated/utsrelease.h
+prepare1: prepare3 outputmakefile asm-generic $(version_h) $(autoksyms_h) \
+						include/generated/utsrelease.h
 	$(cmd_crmodverdir)
 
 archprepare: archheaders archscripts prepare1 scripts
@@ -1517,6 +1506,18 @@ PHONY += $(DOC_TARGETS)
 $(DOC_TARGETS): scripts_basic FORCE
 	$(Q)$(MAKE) $(build)=Documentation $@
 
+# Misc
+# ---------------------------------------------------------------------------
+
+PHONY += scripts_gdb
+scripts_gdb: prepare
+	$(Q)$(MAKE) $(build)=scripts/gdb
+	$(Q)ln -fsn $(abspath $(srctree)/scripts/gdb/vmlinux-gdb.py)
+
+ifdef CONFIG_GDB_SCRIPTS
+all: scripts_gdb
+endif
+
 else # KBUILD_EXTMOD
 
 ###
@@ -1668,6 +1669,11 @@ image_name:
 	@echo $(KBUILD_IMAGE)
 
 # Clear a bunch of variables before executing the submake
+
+ifeq ($(quiet),silent_)
+tools_silent=s
+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/
@@ -1686,45 +1692,32 @@ tools/%: FORCE
 #  target-dir => where to store outputfile
 #  build-dir  => directory in kernel source tree to use
 
-ifeq ($(KBUILD_EXTMOD),)
-        build-dir  = $(patsubst %/,%,$(dir $@))
-        target-dir = $(dir $@)
-else
-        zap-slash=$(filter-out .,$(patsubst %/,%,$(dir $@)))
-        build-dir  = $(KBUILD_EXTMOD)$(if $(zap-slash),/$(zap-slash))
-        target-dir = $(if $(KBUILD_EXTMOD),$(dir $<),$(dir $@))
-endif
-
-%.s: %.c prepare FORCE
-	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.i: %.c prepare FORCE
-	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.o: %.c prepare FORCE
-	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.lst: %.c prepare FORCE
-	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.s: %.S prepare FORCE
-	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.o: %.S prepare FORCE
-	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.symtypes: %.c prepare FORCE
-	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.ll: %.c prepare FORCE
-	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
+build-target = $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD)/)$@
+build-dir = $(patsubst %/,%,$(dir $(build-target)))
+
+%.i: prepare FORCE
+	$(Q)$(MAKE) $(build)=$(build-dir) $(build-target)
+%.ll: prepare FORCE
+	$(Q)$(MAKE) $(build)=$(build-dir) $(build-target)
+%.lst: prepare FORCE
+	$(Q)$(MAKE) $(build)=$(build-dir) $(build-target)
+%.o: prepare FORCE
+	$(Q)$(MAKE) $(build)=$(build-dir) $(build-target)
+%.s: prepare FORCE
+	$(Q)$(MAKE) $(build)=$(build-dir) $(build-target)
+%.symtypes: prepare FORCE
+	$(Q)$(MAKE) $(build)=$(build-dir) $(build-target)
+%.ko: %.o
+	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
 
 # Modules
-/: prepare FORCE
-	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
-	$(build)=$(build-dir)
+PHONY += /
+/: ./
+
 # Make sure the latest headers are built for Documentation
 Documentation/ samples/: headers_install
 %/: prepare FORCE
-	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
-	$(build)=$(build-dir)
-%.ko: prepare FORCE
-	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1)   \
-	$(build)=$(build-dir) $(@:.ko=.o)
-	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
+	$(Q)$(MAKE) KBUILD_MODULES=1 $(build)=$(build-dir)
 
 # FIXME Should go into a make.lib or something
 # ===========================================================================
@@ -1748,13 +1741,11 @@ cmd_crmodverdir = $(Q)mkdir -p $(MODVERDIR) \
 # read saved command lines for existing targets
 existing-targets := $(wildcard $(sort $(targets)))
 
-cmd_files := $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
-$(cmd_files): ;	# Do not try to update included dependency files
--include $(cmd_files)
+-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
 
 endif   # ifeq ($(config-targets),1)
 endif   # ifeq ($(mixed-targets),1)
-endif	# skip-makefile
+endif   # sub-make-done
 
 PHONY += FORCE
 FORCE:

arch/mips/boot/Makefile

@@ -115,7 +115,7 @@ endif
 targets += vmlinux.its.S
 
 quiet_cmd_its_cat = CAT     $@
-      cmd_its_cat = cat $(filter-out $(PHONY), $^) >$@
+      cmd_its_cat = cat $(real-prereqs) >$@
 
 $(obj)/vmlinux.its.S: $(addprefix $(srctree)/arch/mips/$(PLATFORM)/,$(ITS_INPUTS)) FORCE
 	$(call if_changed,its_cat)

arch/powerpc/boot/Makefile

@@ -218,7 +218,7 @@ quiet_cmd_bootas = BOOTAS  $@
       cmd_bootas = $(BOOTCC) -Wp,-MD,$(depfile) $(BOOTAFLAGS) -c -o $@ $<
 
 quiet_cmd_bootar = BOOTAR  $@
-      cmd_bootar = $(BOOTAR) $(BOOTARFLAGS) $@.$$$$ $(filter-out FORCE,$^); mv $@.$$$$ $@
+      cmd_bootar = $(BOOTAR) $(BOOTARFLAGS) $@.$$$$ $(real-prereqs); mv $@.$$$$ $@
 
 $(obj-libfdt): $(obj)/%.o: $(srctree)/scripts/dtc/libfdt/%.c FORCE
 	$(call if_changed_dep,bootcc)

arch/s390/boot/Makefile

@@ -58,7 +58,7 @@ $(obj)/compressed/vmlinux: $(obj)/startup.a FORCE
 	$(Q)$(MAKE) $(build)=$(obj)/compressed $@
 
 quiet_cmd_ar = AR      $@
-      cmd_ar = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(filter $(OBJECTS), $^)
+      cmd_ar = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(real-prereqs)
 
 $(obj)/startup.a: $(OBJECTS) FORCE
 	$(call if_changed,ar)
@@ -67,6 +67,6 @@ install: $(CONFIGURE) $(obj)/bzImage
 	sh -x  $(srctree)/$(obj)/install.sh $(KERNELRELEASE) $(obj)/bzImage \
 	      System.map "$(INSTALL_PATH)"
 
-chkbss := $(OBJECTS)
-chkbss-target := $(obj)/startup.a
+chkbss := $(obj-y)
+chkbss-target := startup.a
 include $(srctree)/arch/s390/scripts/Makefile.chkbss

arch/s390/boot/compressed/Makefile

@@ -63,6 +63,6 @@ OBJCOPYFLAGS_piggy.o := -I binary -O elf64-s390 -B s390:64-bit --rename-section
 $(obj)/piggy.o: $(obj)/vmlinux.bin$(suffix-y) FORCE
 	$(call if_changed,objcopy)
 
-chkbss := $(filter-out $(obj)/piggy.o $(obj)/info.o,$(OBJECTS))
-chkbss-target := $(obj)/vmlinux.bin
+chkbss := $(filter-out piggy.o info.o, $(obj-y))
+chkbss-target := vmlinux.bin
 include $(srctree)/arch/s390/scripts/Makefile.chkbss

arch/s390/scripts/Makefile.chkbss

 # SPDX-License-Identifier: GPL-2.0
 
+chkbss-target ?= built-in.a
+$(obj)/$(chkbss-target): chkbss
+
+chkbss-files := $(addsuffix .chkbss, $(chkbss))
+clean-files += $(chkbss-files)
+
+PHONY += chkbss
+chkbss: $(addprefix $(obj)/, $(chkbss-files))
+
 quiet_cmd_chkbss = CHKBSS  $<
-define cmd_chkbss
-	rm -f $@; \
+      cmd_chkbss = \
 	if ! $(OBJDUMP) -j .bss -w -h $< | awk 'END { if ($$3) exit 1 }'; then \
 		echo "error: $< .bss section is not empty" >&2; exit 1; \
 	fi; \
 	touch $@;
-endef
-
-chkbss-target ?= $(obj)/built-in.a
-ifneq (,$(findstring /,$(chkbss)))
-chkbss-files := $(patsubst %, %.chkbss, $(chkbss))
-else
-chkbss-files := $(patsubst %, $(obj)/%.chkbss, $(chkbss))
-endif
-
-$(chkbss-target): $(chkbss-files)
-targets += $(notdir $(chkbss-files))
 
-%.o.chkbss: %.o
+$(obj)/%.o.chkbss: $(obj)/%.o
 	$(call cmd,chkbss)

arch/x86/realmode/rm/Makefile

@@ -37,8 +37,7 @@ REALMODE_OBJS = $(addprefix $(obj)/,$(realmode-y))
 sed-pasyms := -n -r -e 's/^([0-9a-fA-F]+) [ABCDGRSTVW] (.+)$$/pa_\2 = \2;/p'
 
 quiet_cmd_pasyms = PASYMS  $@
-      cmd_pasyms = $(NM) $(filter-out FORCE,$^) | \
-		   sed $(sed-pasyms) | sort | uniq > $@
+      cmd_pasyms = $(NM) $(real-prereqs) | sed $(sed-pasyms) | sort | uniq > $@
 
 targets += pasyms.h
 $(obj)/pasyms.h: $(REALMODE_OBJS) FORCE

init/Kconfig

@@ -13,7 +13,7 @@ config CC_IS_GCC
 
 config GCC_VERSION
 	int
-	default $(shell,$(srctree)/scripts/gcc-version.sh -p $(CC) | sed 's/^0*//') if CC_IS_GCC
+	default $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) if CC_IS_GCC
 	default 0
 
 config CC_IS_CLANG
@@ -26,6 +26,22 @@ config CLANG_VERSION
 config CC_HAS_ASM_GOTO
 	def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
 
+config CC_HAS_WARN_MAYBE_UNINITIALIZED
+	def_bool $(cc-option,-Wmaybe-uninitialized)
+	help
+	  GCC >= 4.7 supports this option.
+
+config CC_DISABLE_WARN_MAYBE_UNINITIALIZED
+	bool
+	depends on CC_HAS_WARN_MAYBE_UNINITIALIZED
+	default CC_IS_GCC && GCC_VERSION < 40900  # unreliable for GCC < 4.9
+	help
+	  GCC's -Wmaybe-uninitialized is not reliable by definition.
+	  Lots of false positive warnings are produced in some cases.
+
+	  If this option is enabled, -Wno-maybe-uninitialzed is passed
+	  to the compiler to suppress maybe-uninitialized warnings.
+
 config CONSTRUCTORS
 	bool
 	depends on !UML
@@ -1114,6 +1130,7 @@ config CC_OPTIMIZE_FOR_PERFORMANCE
 
 config CC_OPTIMIZE_FOR_SIZE
 	bool "Optimize for size"
+	imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED  # avoid false positives
 	help
 	  Enabling this option will pass "-Os" instead of "-O2" to
 	  your compiler resulting in a smaller kernel.

kernel/trace/Kconfig

@@ -370,6 +370,7 @@ config PROFILE_ANNOTATED_BRANCHES
 config PROFILE_ALL_BRANCHES
 	bool "Profile all if conditionals" if !FORTIFY_SOURCE
 	select TRACE_BRANCH_PROFILING
+	imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED  # avoid false positives
 	help
 	  This tracer profiles all branch conditions. Every if ()
 	  taken in the kernel is recorded whether it hit or miss.

lib/Kconfig.debug

@@ -196,6 +196,7 @@ config DEBUG_INFO_REDUCED
 config DEBUG_INFO_SPLIT
 	bool "Produce split debuginfo in .dwo files"
 	depends on DEBUG_INFO
+	depends on $(cc-option,-gsplit-dwarf)
 	help
 	  Generate debug info into separate .dwo files. This significantly
 	  reduces the build directory size for builds with DEBUG_INFO,
@@ -211,6 +212,7 @@ config DEBUG_INFO_SPLIT
 config DEBUG_INFO_DWARF4
 	bool "Generate dwarf4 debuginfo"
 	depends on DEBUG_INFO
+	depends on $(cc-option,-gdwarf-4)
 	help
 	  Generate dwarf4 debug info. This requires recent versions
 	  of gcc and gdb. It makes the debug information larger.

scripts/Kbuild.include

@@ -23,6 +23,10 @@ depfile = $(subst $(comma),_,$(dot-target).d)
 # filename of target with directory and extension stripped
 basetarget = $(basename $(notdir $@))
 
+###
+# real prerequisites without phony targets
+real-prereqs = $(filter-out $(PHONY), $^)
+
 ###
 # Escape single quote for use in echo statements
 escsq = $(subst $(squote),'\$(squote)',$1)
@@ -67,14 +71,10 @@ endef
 
 # cc-cross-prefix
 # Usage: CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu- m68k-linux-)
-# Return first prefix where a prefix$(CC) is found in PATH.
-# If no $(CC) found in PATH with listed prefixes return nothing
-cc-cross-prefix =  \
-	$(word 1, $(foreach c,$(1),                                   \
-		$(shell set -e;                                       \
-		if (which $(strip $(c))$(CC)) > /dev/null 2>&1 ; then \
-			echo $(c);                                    \
-		fi)))
+# Return first <prefix> where a <prefix>gcc is found in PATH.
+# If no gcc found in PATH with listed prefixes return nothing
+cc-cross-prefix = $(firstword $(foreach c, $(filter-out -%, $(1)), \
+					$(if $(shell which $(c)gcc), $(c))))
 
 # output directory for tests below
 TMPOUT := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/)
@@ -134,12 +134,9 @@ cc-option-yn = $(call try-run,\
 cc-disable-warning = $(call try-run,\
 	$(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
 
-# cc-version
-cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC))
-
 # cc-ifversion
 # Usage:  EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
-cc-ifversion = $(shell [ $(cc-version) $(1) $(2) ] && echo $(3) || echo $(4))
+cc-ifversion = $(shell [ $(CONFIG_GCC_VERSION)0 $(1) $(2)000 ] && echo $(3) || echo $(4))
 
 # cc-ldoption
 # Usage: ldflags += $(call cc-ldoption, -Wl$(comma)--hash-style=both)

scripts/Kconfig.include

@@ -27,4 +27,4 @@ cc-option = $(success,$(CC) -Werror $(1) -E -x c /dev/null -o /dev/null)
 ld-option = $(success,$(LD) -v $(1))
 
 # gcc version including patch level
-gcc-version := $(shell,$(srctree)/scripts/gcc-version.sh -p $(CC) | sed 's/^0*//')
+gcc-version := $(shell,$(srctree)/scripts/gcc-version.sh $(CC))

scripts/Makefile

@@ -39,7 +39,6 @@ build_unifdef: $(obj)/unifdef
 subdir-$(CONFIG_GCC_PLUGINS) += gcc-plugins
 subdir-$(CONFIG_MODVERSIONS) += genksyms
 subdir-$(CONFIG_SECURITY_SELINUX) += selinux
-subdir-$(CONFIG_GDB_SCRIPTS) += gdb
 
 # Let clean descend into subdirs
-subdir-	+= basic dtc kconfig mod package
+subdir-	+= basic dtc gdb kconfig mod package

scripts/Makefile.build

@@ -63,7 +63,9 @@ ifneq ($(strip $(real-obj-y) $(need-builtin)),)
 builtin-target := $(obj)/built-in.a
 endif
 
+ifdef CONFIG_MODULES
 modorder-target := $(obj)/modules.order
+endif
 
 # We keep a list of all modules in $(MODVERDIR)
 
@@ -104,7 +106,7 @@ modkern_cflags =                                          \
 quiet_modtag = $(if $(part-of-module),[M],   )
 
 quiet_cmd_cc_s_c = CC $(quiet_modtag)  $@
-cmd_cc_s_c       = $(CC) $(c_flags) $(DISABLE_LTO) -fverbose-asm -S -o $@ $<
+      cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS), $(c_flags)) $(DISABLE_LTO) -fverbose-asm -S -o $@ $<
 
 $(obj)/%.s: $(src)/%.c FORCE
 	$(call if_changed_dep,cc_s_c)
@@ -118,7 +120,7 @@ $(obj)/%.i: $(src)/%.c FORCE
 # These mirror gensymtypes_S and co below, keep them in synch.
 cmd_gensymtypes_c =                                                         \
     $(CPP) -D__GENKSYMS__ $(c_flags) $< |                                   \
-    $(GENKSYMS) $(if $(1), -T $(2))                                         \
+    scripts/genksyms/genksyms $(if $(1), -T $(2))                           \
      $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS))                             \
      $(if $(KBUILD_PRESERVE),-p)                                            \
      -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
@@ -312,13 +314,13 @@ $(real-obj-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
 #
 # These mirror gensymtypes_c and co above, keep them in synch.
 cmd_gensymtypes_S =                                                         \
-    (echo "\#include <linux/kernel.h>" ;                                    \
+   { echo "\#include <linux/kernel.h>" ;                                    \
      echo "\#include <asm/asm-prototypes.h>" ;                              \
     $(CPP) $(a_flags) $< |                                                  \
      grep "\<___EXPORT_SYMBOL\>" |                                          \
-     sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ) | \
+     sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ; } | \
     $(CPP) -D__GENKSYMS__ $(c_flags) -xc - |                                \
-    $(GENKSYMS) $(if $(1), -T $(2))                                         \
+    scripts/genksyms/genksyms $(if $(1), -T $(2))                           \
      $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS))                             \
      $(if $(KBUILD_PRESERVE),-p)                                            \
      -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
@@ -394,17 +396,12 @@ $(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
 $(sort $(subdir-obj-y)): $(subdir-ym) ;
 
 #
-# Rule to compile a set of .o files into one .o file
+# Rule to compile a set of .o files into one .a file (without symbol table)
 #
 ifdef builtin-target
 
-# built-in.a archives are made with no symbol table or index which
-# makes them small and fast, but unable to be used by the linker.
-# scripts/link-vmlinux.sh builds an aggregate built-in.a with a symbol
-# table and index.
 quiet_cmd_ar_builtin = AR      $@
-      cmd_ar_builtin = rm -f $@; \
-                     $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(filter $(real-obj-y), $^)
+      cmd_ar_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(real-prereqs)
 
 $(builtin-target): $(real-obj-y) FORCE
 	$(call if_changed,ar_builtin)
@@ -426,13 +423,13 @@ $(modorder-target): $(subdir-ym) FORCE
 	$(Q)(cat /dev/null; $(modorder-cmds)) > $@
 
 #
-# Rule to compile a set of .o files into one .a file
+# Rule to compile a set of .o files into one .a file (with symbol table)
 #
 ifdef lib-target
 quiet_cmd_link_l_target = AR      $@
 
 # lib target archives do get a symbol table and index
-cmd_link_l_target = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(lib-y)
+cmd_link_l_target = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(real-prereqs)
 
 $(lib-target): $(lib-y) FORCE
 	$(call if_changed,link_l_target)
@@ -457,6 +454,10 @@ targets += $(obj)/lib-ksyms.o
 
 endif
 
+# NOTE:
+# Do not replace $(filter %.o,^) with $(real-prereqs). When a single object
+# module is turned into a multi object module, $^ will contain header file
+# dependencies recorded in the .*.cmd file.
 quiet_cmd_link_multi-m = LD [M]  $@
 cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(filter %.o,$^) $(cmd_secanalysis)
 

scripts/Makefile.host

@@ -67,13 +67,15 @@ _hostc_flags   = $(KBUILD_HOSTCFLAGS)   $(HOST_EXTRACFLAGS)   \
 _hostcxx_flags = $(KBUILD_HOSTCXXFLAGS) $(HOST_EXTRACXXFLAGS) \
                  $(HOSTCXXFLAGS_$(basetarget).o)
 
-ifeq ($(KBUILD_SRC),)
 __hostc_flags	= $(_hostc_flags)
 __hostcxx_flags	= $(_hostcxx_flags)
-else
+
+ifeq ($(KBUILD_EXTMOD),)
+ifneq ($(KBUILD_SRC),)
 __hostc_flags	= -I$(obj) $(call flags,_hostc_flags)
 __hostcxx_flags	= -I$(obj) $(call flags,_hostcxx_flags)
 endif
+endif
 
 hostc_flags    = -Wp,-MD,$(depfile) $(__hostc_flags)
 hostcxx_flags  = -Wp,-MD,$(depfile) $(__hostcxx_flags)

scripts/Makefile.lib

@@ -137,14 +137,14 @@ _c_flags += $(if $(patsubst n%,, \
 	$(CFLAGS_KCOV))
 endif
 
-# If building the kernel in a separate objtree expand all occurrences
-# of -Idir to -I$(srctree)/dir except for absolute paths (starting with '/').
-
-ifeq ($(KBUILD_SRC),)
 __c_flags	= $(_c_flags)
 __a_flags	= $(_a_flags)
 __cpp_flags     = $(_cpp_flags)
-else
+
+# If building the kernel in a separate objtree expand all occurrences
+# of -Idir to -I$(srctree)/dir except for absolute paths (starting with '/').
+ifeq ($(KBUILD_EXTMOD),)
+ifneq ($(KBUILD_SRC),)
 
 # -I$(obj) locates generated .h files
 # $(call addtree,-I$(obj)) locates .h files in srctree, from generated .c files
@@ -155,6 +155,7 @@ __c_flags	= $(if $(obj),$(call addtree,-I$(src)) -I$(obj)) \
 __a_flags	= $(call flags,_a_flags)
 __cpp_flags     = $(call flags,_cpp_flags)
 endif
+endif
 
 c_flags        = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \
 		 -include $(srctree)/include/linux/compiler_types.h       \
@@ -230,7 +231,7 @@ $(obj)/%: $(src)/%_shipped
 # ---------------------------------------------------------------------------
 
 quiet_cmd_ld = LD      $@
-cmd_ld = $(LD) $(ld_flags) $(filter-out FORCE,$^) -o $@
+      cmd_ld = $(LD) $(ld_flags) $(real-prereqs) -o $@
 
 # Objcopy
 # ---------------------------------------------------------------------------
@@ -242,7 +243,7 @@ cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@
 # ---------------------------------------------------------------------------
 
 quiet_cmd_gzip = GZIP    $@
-      cmd_gzip = cat $(filter-out FORCE,$^) | gzip -n -f -9 > $@
+      cmd_gzip = cat $(real-prereqs) | gzip -n -f -9 > $@
 
 # DTC
 # ---------------------------------------------------------------------------
@@ -270,7 +271,7 @@ DTC_FLAGS += $(DTC_FLAGS_$(basetarget))
 # Generate an assembly file to wrap the output of the device tree compiler
 quiet_cmd_dt_S_dtb= DTB     $@
 cmd_dt_S_dtb=						\
-(							\
+{							\
 	echo '\#include <asm-generic/vmlinux.lds.h>'; 	\
 	echo '.section .dtb.init.rodata,"a"';		\
 	echo '.balign STRUCT_ALIGNMENT';		\
@@ -280,7 +281,7 @@ cmd_dt_S_dtb=						\
 	echo '__dtb_$(subst -,_,$(*F))_end:';		\
 	echo '.global __dtb_$(subst -,_,$(*F))_end';	\
 	echo '.balign STRUCT_ALIGNMENT'; 		\
-) > $@
+} > $@
 
 $(obj)/%.dtb.S: $(obj)/%.dtb FORCE
 	$(call if_changed,dt_S_dtb)
@@ -320,7 +321,7 @@ dtc-tmp = $(subst $(comma),_,$(dot-target).dts.tmp)
 # append the size as a 32-bit littleendian number as gzip does.
 size_append = printf $(shell						\
 dec_size=0;								\
-for F in $1; do								\
+for F in $(real-prereqs); do					\
 	fsize=$$($(CONFIG_SHELL) $(srctree)/scripts/file-size.sh $$F);	\
 	dec_size=$$(expr $$dec_size + $$fsize);				\
 done;									\
@@ -334,23 +335,20 @@ printf "%08x\n" $$dec_size |						\
 )
 
 quiet_cmd_bzip2 = BZIP2   $@
-cmd_bzip2 = (cat $(filter-out FORCE,$^) | \
-	bzip2 -9 && $(call size_append, $(filter-out FORCE,$^))) > $@
+      cmd_bzip2 = { cat $(real-prereqs) | bzip2 -9 && $(size_append); } > $@
 
 # Lzma
 # ---------------------------------------------------------------------------
 
 quiet_cmd_lzma = LZMA    $@
-cmd_lzma = (cat $(filter-out FORCE,$^) | \
-	lzma -9 && $(call size_append, $(filter-out FORCE,$^))) > $@
+      cmd_lzma = { cat $(real-prereqs) | lzma -9 && $(size_append); } > $@
 
 quiet_cmd_lzo = LZO     $@
-cmd_lzo = (cat $(filter-out FORCE,$^) | \
-	lzop -9 && $(call size_append, $(filter-out FORCE,$^))) > $@
+      cmd_lzo = { cat $(real-prereqs) | lzop -9 && $(size_append); } > $@
 
 quiet_cmd_lz4 = LZ4     $@
-cmd_lz4 = (cat $(filter-out FORCE,$^) | \
-	lz4c -l -c1 stdin stdout && $(call size_append, $(filter-out FORCE,$^))) > $@
+      cmd_lz4 = { cat $(real-prereqs) | lz4c -l -c1 stdin stdout && \
+                  $(size_append); } > $@
 
 # U-Boot mkimage
 # ---------------------------------------------------------------------------
@@ -392,13 +390,11 @@ quiet_cmd_uimage = UIMAGE  $@
 # big dictionary would increase the memory usage too much in the multi-call
 # decompression mode. A BCJ filter isn't used either.
 quiet_cmd_xzkern = XZKERN  $@
-cmd_xzkern = (cat $(filter-out FORCE,$^) | \
-	sh $(srctree)/scripts/xz_wrap.sh && \
-	$(call size_append, $(filter-out FORCE,$^))) > $@
+      cmd_xzkern = { cat $(real-prereqs) | sh $(srctree)/scripts/xz_wrap.sh && \
+                     $(size_append); } > $@
 
 quiet_cmd_xzmisc = XZMISC  $@
-cmd_xzmisc = (cat $(filter-out FORCE,$^) | \
-	xz --check=crc32 --lzma2=dict=1MiB) > $@
+      cmd_xzmisc = cat $(real-prereqs) | xz --check=crc32 --lzma2=dict=1MiB > $@
 
 # ASM offsets
 # ---------------------------------------------------------------------------

scripts/Makefile.modpost

@@ -122,7 +122,7 @@ quiet_cmd_ld_ko_o = LD [M]  $@
       cmd_ld_ko_o =                                                     \
 	$(LD) -r $(KBUILD_LDFLAGS)                                      \
                  $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE)             \
-                 -o $@ $(filter-out FORCE,$^) ;                         \
+                 -o $@ $(real-prereqs) ;                                \
 	$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
 
 $(modules): %.ko :%.o %.mod.o FORCE

scripts/clang-version.sh

 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 #
-# clang-version [-p] clang-command
-#
-# Prints the compiler version of `clang-command' in a canonical 4-digit form
-# such as `0500' for clang-5.0 etc.
-#
-# With the -p option, prints the patchlevel as well, for example `050001' for
-# clang-5.0.1 etc.
+# clang-version clang-command
 #
+# Print the compiler version of `clang-command' in a 5 or 6-digit form
+# such as `50001' for clang-5.0.1 etc.
 
 compiler="$*"
 

scripts/gcc-version.sh

 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 #
-# gcc-version [-p] gcc-command
-#
-# Prints the gcc version of `gcc-command' in a canonical 4-digit form
-# such as `0295' for gcc-2.95, `0303' for gcc-3.3, etc.
-#
-# With the -p option, prints the patchlevel as well, for example `029503' for
-# gcc-2.95.3, `030301' for gcc-3.3.1, etc.
+# gcc-version gcc-command
 #
-
-if [ "$1" = "-p" ] ; then
-	with_patchlevel=1;
-	shift;
-fi
+# Print the gcc version of `gcc-command' in a 5 or 6-digit form
+# such as `29503' for gcc-2.95.3, `30301' for gcc-3.3.1, etc.
 
 compiler="$*"
 
 if [ ${#compiler} -eq 0 ]; then
-	echo "Error: No compiler specified."
-	printf "Usage:\n\t$0 <gcc-command>\n"
+	echo "Error: No compiler specified." >&2
+	printf "Usage:\n\t$0 <gcc-command>\n" >&2
 	exit 1
 fi
 
 MAJOR=$(echo __GNUC__ | $compiler -E -x c - | tail -n 1)
 MINOR=$(echo __GNUC_MINOR__ | $compiler -E -x c - | tail -n 1)
-if [ "x$with_patchlevel" != "x" ] ; then
-	PATCHLEVEL=$(echo __GNUC_PATCHLEVEL__ | $compiler -E -x c - | tail -n 1)
-	printf "%02d%02d%02d\\n" $MAJOR $MINOR $PATCHLEVEL
-else
-	printf "%02d%02d\\n" $MAJOR $MINOR
-fi
+PATCHLEVEL=$(echo __GNUC_PATCHLEVEL__ | $compiler -E -x c - | tail -n 1)
+printf "%d%02d%02d\\n" $MAJOR $MINOR $PATCHLEVEL

scripts/gdb/linux/Makefile

 # SPDX-License-Identifier: GPL-2.0
-always := gdb-scripts
 
-SRCTREE := $(abspath $(srctree))
-
-$(obj)/gdb-scripts:
 ifneq ($(KBUILD_SRC),)
-	$(Q)ln -fsn $(SRCTREE)/$(obj)/*.py $(objtree)/$(obj)
+
+symlinks := $(patsubst $(srctree)/$(src)/%,%,$(wildcard $(srctree)/$(src)/*.py))
+
+quiet_cmd_symlink = SYMLINK $@
+      cmd_symlink = ln -fsn $(patsubst $(obj)/%,$(abspath $(srctree))/$(src)/%,$@) $@
+
+extra-y += $(symlinks)
+$(addprefix $(obj)/, $(symlinks)): FORCE
+	$(call if_changed,symlink)
+
 endif
-	@:
 
 quiet_cmd_gen_constants_py = GEN     $@
       cmd_gen_constants_py = \
 	$(CPP) -E -x c -P $(c_flags) $< > $@ ;\
 	sed -i '1,/<!-- end-c-headers -->/d;' $@
 
-targets += constants.py
-$(obj)/constants.py: $(SRCTREE)/$(obj)/constants.py.in FORCE
+extra-y += constants.py
+$(obj)/constants.py: $(src)/constants.py.in FORCE
 	$(call if_changed_dep,gen_constants_py)
 
-build_constants_py: $(obj)/constants.py
-	@:
-
-clean-files := *.pyc *.pyo $(if $(KBUILD_SRC),*.py) $(obj)/constants.py
+clean-files := *.pyc *.pyo

scripts/kallsyms.c

@@ -62,11 +62,11 @@ static int all_symbols = 0;
 static int absolute_percpu = 0;
 static int base_relative = 0;
 
-int token_profit[0x10000];
+static int token_profit[0x10000];
 
 /* the table that holds the result of the compression */
-unsigned char best_table[256][2];
-unsigned char best_table_len[256];
+static unsigned char best_table[256][2];
+static unsigned char best_table_len[256];
 
 
 static void usage(void)
@@ -80,7 +80,7 @@ static void usage(void)
  * This ignores the intensely annoying "mapping symbols" found
  * in ARM ELF files: $a, $t and $d.
  */
-static inline int is_arm_mapping_symbol(const char *str)
+static int is_arm_mapping_symbol(const char *str)
 {
 	return str[0] == '$' && strchr("axtd", str[1])
 	       && (str[2] == '\0' || str[2] == '.');
@@ -331,7 +331,7 @@ static void write_src(void)
 	unsigned int *markers;
 	char buf[KSYM_NAME_LEN];
 
-	printf("#include <asm/types.h>\n");
+	printf("#include <asm/bitsperlong.h>\n");
 	printf("#if BITS_PER_LONG == 64\n");
 	printf("#define PTR .quad\n");
 	printf("#define ALGN .balign 8\n");
@@ -596,9 +596,6 @@ static void insert_real_symbols_in_table(void)
 {
 	unsigned int i, j, c;
 
-	memset(best_table, 0, sizeof(best_table));
-	memset(best_table_len, 0, sizeof(best_table_len));
-
 	for (i = 0; i < table_cnt; i++) {
 		for (j = 0; j < table[i].len; j++) {
 			c = table[i].sym[j];

scripts/kconfig/conf.c

@@ -488,7 +488,6 @@ int main(int ac, char **av)
 	const char *progname = av[0];
 	int opt;
 	const char *name, *defconfig_file = NULL /* gcc uninit */;
-	struct stat tmpstat;
 	int no_conf_write = 0;
 
 	tty_stdio = isatty(0) && isatty(1);
@@ -560,18 +559,6 @@ int main(int ac, char **av)
 	name = av[optind];
 	conf_parse(name);
 	//zconfdump(stdout);
-	if (sync_kconfig) {
-		name = conf_get_configname();
-		if (stat(name, &tmpstat)) {
-			fprintf(stderr, "***\n"
-				"*** Configuration file \"%s\" not found!\n"
-				"***\n"
-				"*** Please run some configurator (e.g. \"make oldconfig\" or\n"
-				"*** \"make menuconfig\" or \"make xconfig\").\n"
-				"***\n", name);
-			exit(1);
-		}
-	}
 
 	switch (input_mode) {
 	case defconfig:

scripts/link-vmlinux.sh

@@ -3,22 +3,17 @@
 #
 # link vmlinux
 #
-# vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_INIT) and
-# $(KBUILD_VMLINUX_MAIN) and $(KBUILD_VMLINUX_LIBS). Most are built-in.a files
-# from top-level directories in the kernel tree, others are specified in
-# arch/$(ARCH)/Makefile. Ordering when linking is important, and
-# $(KBUILD_VMLINUX_INIT) must be first. $(KBUILD_VMLINUX_LIBS) are archives
-# which are linked conditionally (not within --whole-archive), and do not
-# require symbol indexes added.
+# vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_OBJS) and
+# $(KBUILD_VMLINUX_LIBS). Most are built-in.a files from top-level directories
+# in the kernel tree, others are specified in arch/$(ARCH)/Makefile.
+# $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally
+# (not within --whole-archive), and do not require symbol indexes added.
 #
 # vmlinux
 #   ^
 #   |
-#   +-< $(KBUILD_VMLINUX_INIT)
-#   |   +--< init/version.o + more
-#   |
-#   +--< $(KBUILD_VMLINUX_MAIN)
-#   |    +--< drivers/built-in.a mm/built-in.a + more
+#   +--< $(KBUILD_VMLINUX_OBJS)
+#   |    +--< init/built-in.a drivers/built-in.a mm/built-in.a + more
 #   |
 #   +--< $(KBUILD_VMLINUX_LIBS)
 #   |    +--< lib/lib.a + more
@@ -44,24 +39,6 @@ info()
 	fi
 }
 
-# Thin archive build here makes a final archive with symbol table and indexes
-# from vmlinux objects INIT and MAIN, which can be used as input to linker.
-# KBUILD_VMLINUX_LIBS archives should already have symbol table and indexes
-# added.
-#
-# Traditional incremental style of link does not require this step
-#
-# built-in.a output file
-#
-archive_builtin()
-{
-	info AR built-in.a
-	rm -f built-in.a;
-	${AR} rcsTP${KBUILD_ARFLAGS} built-in.a			\
-				${KBUILD_VMLINUX_INIT}		\
-				${KBUILD_VMLINUX_MAIN}
-}
-
 # Link of vmlinux.o used for section mismatch analysis
 # ${1} output file
 modpost_link()
@@ -69,7 +46,7 @@ modpost_link()
 	local objects
 
 	objects="--whole-archive				\
-		built-in.a					\
+		${KBUILD_VMLINUX_OBJS}				\
 		--no-whole-archive				\
 		--start-group					\
 		${KBUILD_VMLINUX_LIBS}				\
@@ -88,7 +65,7 @@ vmlinux_link()
 
 	if [ "${SRCARCH}" != "um" ]; then
 		objects="--whole-archive			\
-			built-in.a				\
+			${KBUILD_VMLINUX_OBJS}			\
 			--no-whole-archive			\
 			--start-group				\
 			${KBUILD_VMLINUX_LIBS}			\
@@ -99,7 +76,7 @@ vmlinux_link()
 			-T ${lds} ${objects}
 	else
 		objects="-Wl,--whole-archive			\
-			built-in.a				\
+			${KBUILD_VMLINUX_OBJS}			\
 			-Wl,--no-whole-archive			\
 			-Wl,--start-group			\
 			${KBUILD_VMLINUX_LIBS}			\
@@ -160,7 +137,6 @@ cleanup()
 	rm -f .tmp_System.map
 	rm -f .tmp_kallsyms*
 	rm -f .tmp_vmlinux*
-	rm -f built-in.a
 	rm -f System.map
 	rm -f vmlinux
 	rm -f vmlinux.o
@@ -217,8 +193,6 @@ fi;
 # final build of init/
 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
 
-archive_builtin
-
 #link vmlinux.o
 info LD vmlinux.o
 modpost_link vmlinux.o

scripts/mkcompile_h

@@ -62,7 +62,7 @@ UTS_TRUNCATE="cut -b -$UTS_LEN"
 
 # Generate a temporary compile.h
 
-( echo /\* This file is auto generated, version $VERSION \*/
+{ echo /\* This file is auto generated, version $VERSION \*/
   if [ -n "$CONFIG_FLAGS" ] ; then echo "/* $CONFIG_FLAGS */"; fi
 
   echo \#define UTS_MACHINE \"$ARCH\"
@@ -73,7 +73,7 @@ UTS_TRUNCATE="cut -b -$UTS_LEN"
   echo \#define LINUX_COMPILE_HOST \"`echo $LINUX_COMPILE_HOST | $UTS_TRUNCATE`\"
 
   echo \#define LINUX_COMPILER \"`$CC -v 2>&1 | grep ' version ' | sed 's/[[:space:]]*$//'`\"
-) > .tmpcompile
+} > .tmpcompile
 
 # Only replace the real compile.h if the new one is different,
 # in order to preserve the timestamp and avoid unnecessary

scripts/package/Makefile

@@ -59,7 +59,7 @@ rpm-pkg: FORCE
 # binrpm-pkg
 # ---------------------------------------------------------------------------
 binrpm-pkg: FORCE
-	$(MAKE) KBUILD_SRC=
+	$(MAKE) -f $(srctree)/Makefile
 	$(CONFIG_SHELL) $(MKSPEC) prebuilt > $(objtree)/binkernel.spec
 	+rpmbuild $(RPMOPTS) --define "_builddir $(objtree)" --target \
 		$(UTS_MACHINE) -bb $(objtree)/binkernel.spec
@@ -72,11 +72,11 @@ deb-pkg: FORCE
 	$(call cmd,src_tar,$(KDEB_SOURCENAME))
 	origversion=$$(dpkg-parsechangelog -SVersion |sed 's/-[^-]*$$//');\
 		mv $(KDEB_SOURCENAME).tar.gz ../$(KDEB_SOURCENAME)_$${origversion}.orig.tar.gz
-	+dpkg-buildpackage -r$(KBUILD_PKG_ROOTCMD) -a$$(cat debian/arch) -i.git -us -uc
+	+dpkg-buildpackage -r$(KBUILD_PKG_ROOTCMD) -a$$(cat debian/arch) $(DPKG_FLAGS) -i.git -us -uc
 
 bindeb-pkg: FORCE
 	$(CONFIG_SHELL) $(srctree)/scripts/package/mkdebian
-	+dpkg-buildpackage -r$(KBUILD_PKG_ROOTCMD) -a$$(cat debian/arch) -b -nc -uc
+	+dpkg-buildpackage -r$(KBUILD_PKG_ROOTCMD) -a$$(cat debian/arch) $(DPKG_FLAGS) -b -nc -uc
 
 intdeb-pkg: FORCE
 	+$(CONFIG_SHELL) $(srctree)/scripts/package/builddeb
@@ -102,7 +102,7 @@ clean-dirs += $(objtree)/snap/
 # tarball targets
 # ---------------------------------------------------------------------------
 tar%pkg: FORCE
-	$(MAKE) KBUILD_SRC=
+	$(MAKE) -f $(srctree)/Makefile
 	$(CONFIG_SHELL) $(srctree)/scripts/package/buildtar $@
 
 clean-dirs += $(objtree)/tar-install/

scripts/package/builddeb

@@ -86,12 +86,12 @@ cp "$($MAKE -s -f $srctree/Makefile image_name)" "$tmpdir/$installed_image_path"
 if grep -q "^CONFIG_OF_EARLY_FLATTREE=y" $KCONFIG_CONFIG ; then
 	# Only some architectures with OF support have this target
 	if [ -d "${srctree}/arch/$SRCARCH/boot/dts" ]; then
-		$MAKE KBUILD_SRC= INSTALL_DTBS_PATH="$tmpdir/usr/lib/$packagename" dtbs_install
+		$MAKE -f $srctree/Makefile INSTALL_DTBS_PATH="$tmpdir/usr/lib/$packagename" dtbs_install
 	fi
 fi
 
 if grep -q '^CONFIG_MODULES=y' $KCONFIG_CONFIG ; then
-	INSTALL_MOD_PATH="$tmpdir" $MAKE KBUILD_SRC= modules_install
+	INSTALL_MOD_PATH="$tmpdir" $MAKE -f $srctree/Makefile modules_install
 	rm -f "$tmpdir/lib/modules/$version/build"
 	rm -f "$tmpdir/lib/modules/$version/source"
 	if [ "$ARCH" = "um" ] ; then
@@ -113,14 +113,14 @@ if grep -q '^CONFIG_MODULES=y' $KCONFIG_CONFIG ; then
 		# resign stripped modules
 		MODULE_SIG_ALL="$(grep -s '^CONFIG_MODULE_SIG_ALL=y' $KCONFIG_CONFIG || true)"
 		if [ -n "$MODULE_SIG_ALL" ]; then
-			INSTALL_MOD_PATH="$tmpdir" $MAKE KBUILD_SRC= modules_sign
+			INSTALL_MOD_PATH="$tmpdir" $MAKE -f $srctree/Makefile modules_sign
 		fi
 	fi
 fi
 
 if [ "$ARCH" != "um" ]; then
-	$MAKE headers_check KBUILD_SRC=
-	$MAKE headers_install KBUILD_SRC= INSTALL_HDR_PATH="$libc_headers_dir/usr"
+	$MAKE -f $srctree/Makefile headers_check
+	$MAKE -f $srctree/Makefile headers_install INSTALL_HDR_PATH="$libc_headers_dir/usr"
 fi
 
 # Install the maintainer scripts

scripts/package/buildtar

@@ -57,7 +57,7 @@ dirs=boot
 # Try to install modules
 #
 if grep -q '^CONFIG_MODULES=y' "${KCONFIG_CONFIG}"; then
-	make ARCH="${ARCH}" O="${objtree}" KBUILD_SRC= INSTALL_MOD_PATH="${tmpdir}" modules_install
+	make ARCH="${ARCH}" -f ${srctree}/Makefile INSTALL_MOD_PATH="${tmpdir}" modules_install
 	dirs="$dirs lib"
 fi
 

scripts/package/mkdebian

@@ -205,13 +205,15 @@ EOF
 cat <<EOF > debian/rules
 #!$(command -v $MAKE) -f
 
+srctree ?= .
+
 build:
 	\$(MAKE) KERNELRELEASE=${version} ARCH=${ARCH} \
-	KBUILD_BUILD_VERSION=${revision} KBUILD_SRC=
+	KBUILD_BUILD_VERSION=${revision} -f \$(srctree)/Makefile
 
 binary-arch:
 	\$(MAKE) KERNELRELEASE=${version} ARCH=${ARCH} \
-	KBUILD_BUILD_VERSION=${revision} KBUILD_SRC= intdeb-pkg
+	KBUILD_BUILD_VERSION=${revision} -f \$(srctree)/Makefile intdeb-pkg
 
 clean:
 	rm -rf debian/*tmp debian/files