Makefile

KBUILD_CFLAGS += $(call cc-disable-warning, restrict)

# Enabled with W=2, disabled by default as noisy
KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized)

# disable invalid "can't wrap" optimizations for signed / pointers
KBUILD_CFLAGS	+= -fno-strict-overflow

# Make sure -fstack-check isn't enabled (like gentoo apparently did)
KBUILD_CFLAGS  += -fno-stack-check

# conserve stack if available
KBUILD_CFLAGS   += $(call cc-option,-fconserve-stack)

# Prohibit date/time macros, which would make the build non-deterministic
KBUILD_CFLAGS   += -Werror=date-time

# enforce correct pointer usage
KBUILD_CFLAGS   += $(call cc-option,-Werror=incompatible-pointer-types)

# Require designated initializers for all marked structures
KBUILD_CFLAGS   += $(call cc-option,-Werror=designated-init)

# change __FILE__ to the relative path from the srctree
KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)

# include additional Makefiles when needed
include-y			:= scripts/Makefile.extrawarn
include-$(CONFIG_KASAN)		+= scripts/Makefile.kasan
include-$(CONFIG_KCSAN)		+= scripts/Makefile.kcsan
include-$(CONFIG_UBSAN)		+= scripts/Makefile.ubsan
include-$(CONFIG_KCOV)		+= scripts/Makefile.kcov
include-$(CONFIG_GCC_PLUGINS)	+= scripts/Makefile.gcc-plugins

include $(addprefix $(srctree)/, $(include-y))

# scripts/Makefile.gcc-plugins is intentionally included last.
# Do not add $(call cc-option,...) below this line. When you build the kernel
# from the clean source tree, the GCC plugins do not exist at this point.

# Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
KBUILD_CPPFLAGS += $(KCPPFLAGS)
KBUILD_AFLAGS   += $(KAFLAGS)
KBUILD_CFLAGS   += $(KCFLAGS)

KBUILD_LDFLAGS_MODULE += --build-id=sha1
LDFLAGS_vmlinux += --build-id=sha1

ifeq ($(CONFIG_STRIP_ASM_SYMS),y)
LDFLAGS_vmlinux	+= $(call ld-option, -X,)
endif

ifeq ($(CONFIG_RELR),y)
LDFLAGS_vmlinux	+= --pack-dyn-relocs=relr --use-android-relr-tags
endif

# We never want expected sections to be placed heuristically by the
# linker. All sections should be explicitly named in the linker script.
ifdef CONFIG_LD_ORPHAN_WARN
LDFLAGS_vmlinux += --orphan-handling=warn
endif

# Align the bit size of userspace programs with the kernel
KBUILD_USERCFLAGS  += $(filter -m32 -m64 --target=%, $(KBUILD_CFLAGS))
KBUILD_USERLDFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CFLAGS))

# make the checker run with the right architecture
CHECKFLAGS += --arch=$(ARCH)

# insure the checker run with the right endianness
CHECKFLAGS += $(if $(CONFIG_CPU_BIG_ENDIAN),-mbig-endian,-mlittle-endian)

# the checker needs the correct machine size
CHECKFLAGS += $(if $(CONFIG_64BIT),-m64,-m32)

# Default kernel image to build when no specific target is given.
# KBUILD_IMAGE may be overruled on the command line or
# set in the environment
# Also any assignments in arch/$(ARCH)/Makefile take precedence over
# this default value
export KBUILD_IMAGE ?= vmlinux

#
# INSTALL_PATH specifies where to place the updated kernel and system map
# images. Default is /boot, but you can set it to other values
export	INSTALL_PATH ?= /boot

#
# INSTALL_DTBS_PATH specifies a prefix for relocations required by build roots.
# Like INSTALL_MOD_PATH, it isn't defined in the Makefile, but can be passed as
# an argument if needed. Otherwise it defaults to the kernel install path
#
export INSTALL_DTBS_PATH ?= $(INSTALL_PATH)/dtbs/$(KERNELRELEASE)

#
# INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
# relocations required by build roots.  This is not defined in the
# makefile but the argument can be passed to make if needed.
#

MODLIB	= $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
export MODLIB

PHONY += prepare0

export extmod_prefix = $(if $(KBUILD_EXTMOD),$(KBUILD_EXTMOD)/)
export MODORDER := $(extmod_prefix)modules.order
export MODULES_NSDEPS := $(extmod_prefix)modules.nsdeps

ifeq ($(KBUILD_EXTMOD),)
core-y		+= kernel/ certs/ mm/ fs/ ipc/ security/ crypto/ block/

vmlinux-dirs	:= $(patsubst %/,%,$(filter %/, \
		     $(core-y) $(core-m) $(drivers-y) $(drivers-m) \
		     $(libs-y) $(libs-m)))

vmlinux-alldirs	:= $(sort $(vmlinux-dirs) Documentation \
		     $(patsubst %/,%,$(filter %/, $(core-) \
			$(drivers-) $(libs-))))

subdir-modorder := $(addsuffix modules.order,$(filter %/, \
			$(core-y) $(core-m) $(libs-y) $(libs-m) \
			$(drivers-y) $(drivers-m)))

build-dirs	:= $(vmlinux-dirs)
clean-dirs	:= $(vmlinux-alldirs)

# Externally visible symbols (used by link-vmlinux.sh)
KBUILD_VMLINUX_OBJS := $(head-y) $(patsubst %/,%/built-in.a, $(core-y))
KBUILD_VMLINUX_OBJS += $(addsuffix built-in.a, $(filter %/, $(libs-y)))
ifdef CONFIG_MODULES
KBUILD_VMLINUX_OBJS += $(patsubst %/, %/lib.a, $(filter %/, $(libs-y)))
KBUILD_VMLINUX_LIBS := $(filter-out %/, $(libs-y))
else
KBUILD_VMLINUX_LIBS := $(patsubst %/,%/lib.a, $(libs-y))
endif
KBUILD_VMLINUX_OBJS += $(patsubst %/,%/built-in.a, $(drivers-y))

export KBUILD_VMLINUX_OBJS KBUILD_VMLINUX_LIBS
export KBUILD_LDS          := arch/$(SRCARCH)/kernel/vmlinux.lds
# used by scripts/Makefile.package
export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) LICENSES arch include scripts tools)

vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)

# Recurse until adjust_autoksyms.sh is satisfied
PHONY += autoksyms_recursive
ifdef CONFIG_TRIM_UNUSED_KSYMS
# For the kernel to actually contain only the needed exported symbols,
# we have to build modules as well to determine what those symbols are.
# (this can be evaluated only once include/config/auto.conf has been included)
KBUILD_MODULES := 1

autoksyms_recursive: descend modules.order
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/adjust_autoksyms.sh \
	  "$(MAKE) -f $(srctree)/Makefile vmlinux"
endif

autoksyms_h := $(if $(CONFIG_TRIM_UNUSED_KSYMS), include/generated/autoksyms.h)

quiet_cmd_autoksyms_h = GEN     $@
      cmd_autoksyms_h = mkdir -p $(dir $@); \
			$(CONFIG_SHELL) $(srctree)/scripts/gen_autoksyms.sh $@

$(autoksyms_h):
	$(call cmd,autoksyms_h)

ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)

# Final link of vmlinux with optional arch pass after final link
cmd_link-vmlinux =                                                 \
	$(CONFIG_SHELL) $< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)";    \
	$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)

vmlinux: scripts/link-vmlinux.sh autoksyms_recursive $(vmlinux-deps) FORCE
	+$(call if_changed_dep,link-vmlinux)

targets := vmlinux

# The actual objects are generated when descending,
# make sure no implicit rule kicks in
$(sort $(vmlinux-deps) $(subdir-modorder)): descend ;

filechk_kernel.release = \
	echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"

# Store (new) KERNELRELEASE string in include/config/kernel.release
include/config/kernel.release: FORCE
	$(call filechk,kernel.release)

# Additional helpers built in scripts/
# Carefully list dependencies so we do not try to build scripts twice
# in parallel
PHONY += scripts
scripts: scripts_basic scripts_dtc
	$(Q)$(MAKE) $(build)=$(@)

# Things we need to do before we recursively start building the kernel
# or the modules are listed in "prepare".
# A multi level approach is used. prepareN is processed before prepareN-1.
# archprepare is used in arch Makefiles and when processed asm symlink,
# version.h and scripts_basic is processed / created.

PHONY += prepare archprepare

archprepare: outputmakefile archheaders archscripts scripts include/config/kernel.release \
	asm-generic $(version_h) $(autoksyms_h) include/generated/utsrelease.h \
	include/generated/autoconf.h remove-stale-files

prepare0: archprepare
	$(Q)$(MAKE) $(build)=scripts/mod
	$(Q)$(MAKE) $(build)=.

# All the preparing..
prepare: prepare0

PHONY += remove-stale-files
remove-stale-files:
	$(Q)$(srctree)/scripts/remove-stale-files

# Support for using generic headers in asm-generic
asm-generic := -f $(srctree)/scripts/Makefile.asm-generic obj

PHONY += asm-generic uapi-asm-generic
asm-generic: uapi-asm-generic
	$(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/asm \
	generic=include/asm-generic
uapi-asm-generic:
	$(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/uapi/asm \
	generic=include/uapi/asm-generic

# Generate some files
# ---------------------------------------------------------------------------

# KERNELRELEASE can change from a few different places, meaning version.h
# needs to be updated, so this check is forced on all builds

uts_len := 64
define filechk_utsrelease.h
	if [ `echo -n "$(KERNELRELEASE)" | wc -c ` -gt $(uts_len) ]; then \
	  echo '"$(KERNELRELEASE)" exceeds $(uts_len) characters' >&2;    \
	  exit 1;                                                         \
	fi;                                                               \
	echo \#define UTS_RELEASE \"$(KERNELRELEASE)\"
endef

define filechk_version.h
	if [ $(SUBLEVEL) -gt 255 ]; then                                 \
		echo \#define LINUX_VERSION_CODE $(shell                 \
		expr $(VERSION) \* 65536 + $(PATCHLEVEL) \* 256 + 255); \
	else                                                             \
		echo \#define LINUX_VERSION_CODE $(shell                 \
		expr $(VERSION) \* 65536 + $(PATCHLEVEL) \* 256 + $(SUBLEVEL)); \
	fi;                                                              \
	echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) +  \
	((c) > 255 ? 255 : (c)))';                                       \
	echo \#define LINUX_VERSION_MAJOR $(VERSION);                    \
	echo \#define LINUX_VERSION_PATCHLEVEL $(PATCHLEVEL);            \
	echo \#define LINUX_VERSION_SUBLEVEL $(SUBLEVEL)
endef

$(version_h): PATCHLEVEL := $(if $(PATCHLEVEL), $(PATCHLEVEL), 0)
$(version_h): SUBLEVEL := $(if $(SUBLEVEL), $(SUBLEVEL), 0)
$(version_h): FORCE
	$(call filechk,version.h)

include/generated/utsrelease.h: include/config/kernel.release FORCE
	$(call filechk,utsrelease.h)

PHONY += headerdep
headerdep:
	$(Q)find $(srctree)/include/ -name '*.h' | xargs --max-args 1 \
	$(srctree)/scripts/headerdep.pl -I$(srctree)/include

# ---------------------------------------------------------------------------
# Kernel headers

#Default location for installed headers
export INSTALL_HDR_PATH = $(objtree)/usr

quiet_cmd_headers_install = INSTALL $(INSTALL_HDR_PATH)/include
      cmd_headers_install = \
	mkdir -p $(INSTALL_HDR_PATH); \
	rsync -mrl --include='*/' --include='*\.h' --exclude='*' \
	usr/include $(INSTALL_HDR_PATH)

PHONY += headers_install
headers_install: headers
	$(call cmd,headers_install)

PHONY += archheaders archscripts

hdr-inst := -f $(srctree)/scripts/Makefile.headersinst obj

PHONY += headers
headers: $(version_h) scripts_unifdef uapi-asm-generic archheaders archscripts
	$(if $(wildcard $(srctree)/arch/$(SRCARCH)/include/uapi/asm/Kbuild),, \
	  $(error Headers not exportable for the $(SRCARCH) architecture))
	$(Q)$(MAKE) $(hdr-inst)=include/uapi
	$(Q)$(MAKE) $(hdr-inst)=arch/$(SRCARCH)/include/uapi

# Deprecated. It is no-op now.
PHONY += headers_check
headers_check:
	@echo >&2 "=================== WARNING ==================="
	@echo >&2 "Since Linux 5.5, 'make headers_check' is no-op,"
	@echo >&2 "and will be removed after Linux 5.15 release."
	@echo >&2 "Please remove headers_check from your scripts."
	@echo >&2 "==============================================="

ifdef CONFIG_HEADERS_INSTALL
prepare: headers
endif

PHONY += scripts_unifdef
scripts_unifdef: scripts_basic
	$(Q)$(MAKE) $(build)=scripts scripts/unifdef

# ---------------------------------------------------------------------------
# Tools

ifdef CONFIG_STACK_VALIDATION
prepare: tools/objtool
endif

ifdef CONFIG_BPF
ifdef CONFIG_DEBUG_INFO_BTF
prepare: tools/bpf/resolve_btfids
endif
endif

PHONY += resolve_btfids_clean

resolve_btfids_O = $(abspath $(objtree))/tools/bpf/resolve_btfids

# tools/bpf/resolve_btfids directory might not exist
# in output directory, skip its clean in that case
resolve_btfids_clean:
ifneq ($(wildcard $(resolve_btfids_O)),)
	$(Q)$(MAKE) -sC $(srctree)/tools/bpf/resolve_btfids O=$(resolve_btfids_O) clean
endif

# 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 $(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 $(srctree)/tools/ $*

# ---------------------------------------------------------------------------
# Kernel selftest

PHONY += kselftest
kselftest:
	$(Q)$(MAKE) -C $(srctree)/tools/testing/selftests run_tests

kselftest-%: FORCE
	$(Q)$(MAKE) -C $(srctree)/tools/testing/selftests $*

PHONY += kselftest-merge
kselftest-merge:
	$(if $(wildcard $(objtree)/.config),, $(error No .config exists, config your kernel first!))
	$(Q)find $(srctree)/tools/testing/selftests -name config | \
		xargs $(srctree)/scripts/kconfig/merge_config.sh -m $(objtree)/.config
	$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig

# ---------------------------------------------------------------------------
# Devicetree files

ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/boot/dts/),)
dtstree := arch/$(SRCARCH)/boot/dts
endif

ifneq ($(dtstree),)

%.dtb: include/config/kernel.release scripts_dtc
	$(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@

%.dtbo: include/config/kernel.release scripts_dtc
	$(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@

PHONY += dtbs dtbs_install dtbs_check
dtbs: include/config/kernel.release scripts_dtc
	$(Q)$(MAKE) $(build)=$(dtstree)

ifneq ($(filter dtbs_check, $(MAKECMDGOALS)),)
export CHECK_DTBS=y
dtbs: dt_binding_check
endif

dtbs_check: dtbs

dtbs_install:
	$(Q)$(MAKE) $(dtbinst)=$(dtstree) dst=$(INSTALL_DTBS_PATH)

ifdef CONFIG_OF_EARLY_FLATTREE
all: dtbs
endif

endif

PHONY += scripts_dtc
scripts_dtc: scripts_basic
	$(Q)$(MAKE) $(build)=scripts/dtc

ifneq ($(filter dt_binding_check, $(MAKECMDGOALS)),)
export CHECK_DT_BINDING=y
endif

PHONY += dt_binding_check
dt_binding_check: scripts_dtc
	$(Q)$(MAKE) $(build)=Documentation/devicetree/bindings

# ---------------------------------------------------------------------------
# Modules

ifdef CONFIG_MODULES

# By default, build modules as well

all: modules

# When we're building modules with modversions, we need to consider
# the built-in objects during the descend as well, in order to
# make sure the checksums are up to date before we record them.
ifdef CONFIG_MODVERSIONS
  KBUILD_BUILTIN := 1
endif

# Build modules
#
# A module can be listed more than once in obj-m resulting in
# duplicate lines in modules.order files.  Those are removed
# using awk while concatenating to the final file.

PHONY += modules
modules: $(if $(KBUILD_BUILTIN),vmlinux) modules_check modules_prepare

cmd_modules_order = $(AWK) '!x[$$0]++' $(real-prereqs) > $@

modules.order: $(subdir-modorder) FORCE
	$(call if_changed,modules_order)

targets += modules.order

# Target to prepare building external modules
PHONY += modules_prepare
modules_prepare: prepare
	$(Q)$(MAKE) $(build)=scripts scripts/module.lds

export modules_sign_only :=

ifeq ($(CONFIG_MODULE_SIG),y)
PHONY += modules_sign
modules_sign: modules_install
	@:

# modules_sign is a subset of modules_install.
# 'make modules_install modules_sign' is equivalent to 'make modules_install'.
ifeq ($(filter modules_install,$(MAKECMDGOALS)),)
modules_sign_only := y
endif
endif

modinst_pre :=
ifneq ($(filter modules_install,$(MAKECMDGOALS)),)
modinst_pre := __modinst_pre
endif

modules_install: $(modinst_pre)
PHONY += __modinst_pre
__modinst_pre:
	@rm -rf $(MODLIB)/kernel
	@rm -f $(MODLIB)/source
	@mkdir -p $(MODLIB)/kernel
	@ln -s $(abspath $(srctree)) $(MODLIB)/source
	@if [ ! $(objtree) -ef  $(MODLIB)/build ]; then \
		rm -f $(MODLIB)/build ; \
		ln -s $(CURDIR) $(MODLIB)/build ; \
	fi
	@sed 's:^:kernel/:' modules.order > $(MODLIB)/modules.order
	@cp -f modules.builtin $(MODLIB)/
	@cp -f $(objtree)/modules.builtin.modinfo $(MODLIB)/

endif # CONFIG_MODULES

###
# Cleaning is done on three levels.
# make clean     Delete most generated files
#                Leave enough to build external modules
# make mrproper  Delete the current configuration, and all generated files
# make distclean Remove editor backup files, patch leftover files and the like

# Directories & files removed with 'make clean'
CLEAN_FILES += include/ksym vmlinux.symvers modules-only.symvers \
	       modules.builtin modules.builtin.modinfo modules.nsdeps \
	       compile_commands.json .thinlto-cache

# Directories & files removed with 'make mrproper'
MRPROPER_FILES += include/config include/generated          \
		  arch/$(SRCARCH)/include/generated .tmp_objdiff \
		  debian snap tar-install \
		  .config .config.old .version \
		  Module.symvers \
		  certs/signing_key.pem certs/signing_key.x509 \
		  certs/x509.genkey \
		  vmlinux-gdb.py \
		  *.spec

# clean - Delete most, but leave enough to build external modules
#
clean: rm-files := $(CLEAN_FILES)

PHONY += archclean vmlinuxclean

vmlinuxclean:
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/link-vmlinux.sh clean
	$(Q)$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) clean)

clean: archclean vmlinuxclean resolve_btfids_clean

# mrproper - Delete all generated files, including .config
#
mrproper: rm-files := $(wildcard $(MRPROPER_FILES))
mrproper-dirs      := $(addprefix _mrproper_,scripts)

PHONY += $(mrproper-dirs) mrproper
$(mrproper-dirs):
	$(Q)$(MAKE) $(clean)=$(patsubst _mrproper_%,%,$@)

mrproper: clean $(mrproper-dirs)
	$(call cmd,rmfiles)

# distclean
#
PHONY += distclean

distclean: mrproper
	@find . $(RCS_FIND_IGNORE) \
		\( -name '*.orig' -o -name '*.rej' -o -name '*~' \
		-o -name '*.bak' -o -name '#*#' -o -name '*%' \
		-o -name 'core' -o -name tags -o -name TAGS -o -name 'cscope*' \
		-o -name GPATH -o -name GRTAGS -o -name GSYMS -o -name GTAGS \) \
		-type f -print | xargs rm -f


# Packaging of the kernel to various formats
# ---------------------------------------------------------------------------

%src-pkg: FORCE
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.package $@
%pkg: include/config/kernel.release FORCE
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.package $@

# Brief documentation of the typical targets used
# ---------------------------------------------------------------------------

boards := $(wildcard $(srctree)/arch/$(SRCARCH)/configs/*_defconfig)
boards := $(sort $(notdir $(boards)))
board-dirs := $(dir $(wildcard $(srctree)/arch/$(SRCARCH)/configs/*/*_defconfig))
board-dirs := $(sort $(notdir $(board-dirs:/=)))

PHONY += help
help:
	@echo  'Cleaning targets:'
	@echo  '  clean		  - Remove most generated files but keep the config and'
	@echo  '                    enough build support to build external modules'
	@echo  '  mrproper	  - Remove all generated files + config + various backup files'
	@echo  '  distclean	  - mrproper + remove editor backup and patch files'
	@echo  ''
	@echo  'Configuration targets:'
	@$(MAKE) -f $(srctree)/scripts/kconfig/Makefile help
	@echo  ''
	@echo  'Other generic targets:'
	@echo  '  all		  - Build all targets marked with [*]'
	@echo  '* vmlinux	  - Build the bare kernel'
	@echo  '* modules	  - Build all modules'
	@echo  '  modules_install - Install all modules to INSTALL_MOD_PATH (default: /)'
	@echo  '  dir/            - Build all files in dir and below'
	@echo  '  dir/file.[ois]  - Build specified target only'
	@echo  '  dir/file.ll     - Build the LLVM assembly file'
	@echo  '                    (requires compiler support for LLVM assembly generation)'
	@echo  '  dir/file.lst    - Build specified mixed source/assembly target only'
	@echo  '                    (requires a recent binutils and recent build (System.map))'
	@echo  '  dir/file.ko     - Build module including final link'
	@echo  '  modules_prepare - Set up for building external modules'
	@echo  '  tags/TAGS	  - Generate tags file for editors'
	@echo  '  cscope	  - Generate cscope index'
	@echo  '  gtags           - Generate GNU GLOBAL index'
	@echo  '  kernelrelease	  - Output the release version string (use with make -s)'
	@echo  '  kernelversion	  - Output the version stored in Makefile (use with make -s)'
	@echo  '  image_name	  - Output the image name (use with make -s)'
	@echo  '  headers_install - Install sanitised kernel headers to INSTALL_HDR_PATH'; \
	 echo  '                    (default: $(INSTALL_HDR_PATH))'; \
	 echo  ''
	@echo  'Static analysers:'
	@echo  '  checkstack      - Generate a list of stack hogs'
	@echo  '  versioncheck    - Sanity check on version.h usage'
	@echo  '  includecheck    - Check for duplicate included header files'
	@echo  '  export_report   - List the usages of all exported symbols'
	@echo  '  headerdep       - Detect inclusion cycles in headers'
	@echo  '  coccicheck      - Check with Coccinelle'
	@echo  '  clang-analyzer  - Check with clang static analyzer'
	@echo  '  clang-tidy      - Check with clang-tidy'
	@echo  ''
	@echo  'Tools:'
	@echo  '  nsdeps          - Generate missing symbol namespace dependencies'
	@echo  ''
	@echo  'Kernel selftest:'
	@echo  '  kselftest         - Build and run kernel selftest'
	@echo  '                      Build, install, and boot kernel before'
	@echo  '                      running kselftest on it'
	@echo  '                      Run as root for full coverage'
	@echo  '  kselftest-all     - Build kernel selftest'
	@echo  '  kselftest-install - Build and install kernel selftest'
	@echo  '  kselftest-clean   - Remove all generated kselftest files'
	@echo  '  kselftest-merge   - Merge all the config dependencies of'
	@echo  '		      kselftest to existing .config.'
	@echo  ''
	@$(if $(dtstree), \
		echo 'Devicetree:'; \
		echo '* dtbs             - Build device tree blobs for enabled boards'; \
		echo '  dtbs_install     - Install dtbs to $(INSTALL_DTBS_PATH)'; \
		echo '  dt_binding_check - Validate device tree binding documents'; \
		echo '  dtbs_check       - Validate device tree source files';\
		echo '')

	@echo 'Userspace tools targets:'
	@echo '  use "make tools/help"'
	@echo '  or  "cd tools; make help"'
	@echo  ''
	@echo  'Kernel packaging:'
	@$(MAKE) -f $(srctree)/scripts/Makefile.package help
	@echo  ''
	@echo  'Documentation targets:'
	@$(MAKE) -f $(srctree)/Documentation/Makefile dochelp
	@echo  ''
	@echo  'Architecture specific targets ($(SRCARCH)):'
	@$(if $(archhelp),$(archhelp),\
		echo '  No architecture specific help defined for $(SRCARCH)')
	@echo  ''
	@$(if $(boards), \
		$(foreach b, $(boards), \
		printf "  %-27s - Build for %s\\n" $(b) $(subst _defconfig,,$(b));) \
		echo '')
	@$(if $(board-dirs), \
		$(foreach b, $(board-dirs), \
		printf "  %-16s - Show %s-specific targets\\n" help-$(b) $(b);) \
		printf "  %-16s - Show all of the above\\n" help-boards; \
		echo '')

	@echo  '  make V=0|1 [targets] 0 => quiet build (default), 1 => verbose build'
	@echo  '  make V=2   [targets] 2 => give reason for rebuild of target'
	@echo  '  make O=dir [targets] Locate all output files in "dir", including .config'
	@echo  '  make C=1   [targets] Check re-compiled c source with $$CHECK'
	@echo  '                       (sparse by default)'
	@echo  '  make C=2   [targets] Force check of all c source with $$CHECK'
	@echo  '  make RECORDMCOUNT_WARN=1 [targets] Warn about ignored mcount sections'
	@echo  '  make W=n   [targets] Enable extra build checks, n=1,2,3 where'
	@echo  '		1: warnings which may be relevant and do not occur too often'
	@echo  '		2: warnings which occur quite often but may still be relevant'
	@echo  '		3: more obscure warnings, can most likely be ignored'
	@echo  '		Multiple levels can be combined with W=12 or W=123'
	@echo  ''
	@echo  'Execute "make" or "make all" to build all targets marked with [*] '
	@echo  'For further info see the ./README file'


help-board-dirs := $(addprefix help-,$(board-dirs))

help-boards: $(help-board-dirs)

boards-per-dir = $(sort $(notdir $(wildcard $(srctree)/arch/$(SRCARCH)/configs/$*/*_defconfig)))

$(help-board-dirs): help-%:
	@echo  'Architecture specific targets ($(SRCARCH) $*):'
	@$(if $(boards-per-dir), \
		$(foreach b, $(boards-per-dir), \
		printf "  %-24s - Build for %s\\n" $*/$(b) $(subst _defconfig,,$(b));) \
		echo '')


# Documentation targets
# ---------------------------------------------------------------------------
DOC_TARGETS := xmldocs latexdocs pdfdocs htmldocs epubdocs cleandocs \
	       linkcheckdocs dochelp refcheckdocs
PHONY += $(DOC_TARGETS)
$(DOC_TARGETS):
	$(Q)$(MAKE) $(build)=Documentation $@

# Misc
# ---------------------------------------------------------------------------

PHONY += scripts_gdb
scripts_gdb: prepare0
	$(Q)$(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

###
# External module support.
# When building external modules the kernel used as basis is considered
# read-only, and no consistency checks are made and the make
# system is not used on the basis kernel. If updates are required
# in the basis kernel ordinary make commands (without M=...) must be used.

# We are always building only modules.
KBUILD_BUILTIN :=
KBUILD_MODULES := 1

build-dirs := $(KBUILD_EXTMOD)
$(MODORDER): descend
	@:

compile_commands.json: $(extmod_prefix)compile_commands.json
PHONY += compile_commands.json

clean-dirs := $(KBUILD_EXTMOD)
clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers $(KBUILD_EXTMOD)/modules.nsdeps \
	$(KBUILD_EXTMOD)/compile_commands.json $(KBUILD_EXTMOD)/.thinlto-cache

PHONY += help
help:
	@echo  '  Building external modules.'
	@echo  '  Syntax: make -C path/to/kernel/src M=$$PWD target'
	@echo  ''
	@echo  '  modules         - default target, build the module(s)'
	@echo  '  modules_install - install the module'
	@echo  '  clean           - remove generated files in module directory only'
	@echo  ''

# no-op for external module builds
PHONY += prepare modules_prepare

endif # KBUILD_EXTMOD

# ---------------------------------------------------------------------------
# Modules

PHONY += modules modules_install

ifdef CONFIG_MODULES

modules: modules_check
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost

PHONY += modules_check
modules_check: $(MODORDER)
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/modules-check.sh $<

quiet_cmd_depmod = DEPMOD  $(MODLIB)
      cmd_depmod = $(CONFIG_SHELL) $(srctree)/scripts/depmod.sh $(DEPMOD) \
                   $(KERNELRELEASE)

modules_install:
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst
	$(call cmd,depmod)

else # CONFIG_MODULES

# Modules not configured
# ---------------------------------------------------------------------------

modules modules_install:
	@echo >&2 '***'
	@echo >&2 '*** The present kernel configuration has modules disabled.'
	@echo >&2 '*** To use the module feature, please run "make menuconfig" etc.'
	@echo >&2 '*** to enable CONFIG_MODULES.'
	@echo >&2 '***'
	@exit 1

endif # CONFIG_MODULES

# Single targets
# ---------------------------------------------------------------------------
# To build individual files in subdirectories, you can do like this:
#
#   make foo/bar/baz.s
#
# The supported suffixes for single-target are listed in 'single-targets'
#
# To build only under specific subdirectories, you can do like this:
#
#   make foo/bar/baz/

ifdef single-build

# .ko is special because modpost is needed
single-ko := $(sort $(filter %.ko, $(MAKECMDGOALS)))
single-no-ko := $(sort $(patsubst %.ko,%.mod, $(MAKECMDGOALS)))

$(single-ko): single_modpost
	@:
$(single-no-ko): descend
	@:

ifeq ($(KBUILD_EXTMOD),)
# For the single build of in-tree modules, use a temporary file to avoid
# the situation of modules_install installing an invalid modules.order.
MODORDER := .modules.tmp
endif

PHONY += single_modpost
single_modpost: $(single-no-ko) modules_prepare
	$(Q){ $(foreach m, $(single-ko), echo $(extmod_prefix)$m;) } > $(MODORDER)
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost

KBUILD_MODULES := 1

export KBUILD_SINGLE_TARGETS := $(addprefix $(extmod_prefix), $(single-no-ko))

# trim unrelated directories
build-dirs := $(foreach d, $(build-dirs), \
			$(if $(filter $(d)/%, $(KBUILD_SINGLE_TARGETS)), $(d)))

endif

ifndef CONFIG_MODULES
KBUILD_MODULES :=
endif

# Handle descending into subdirectories listed in $(build-dirs)
# Preset locale variables to speed up the build process. Limit locale
# tweaks to this spot to avoid wrong language settings when running
# make menuconfig etc.
# Error messages still appears in the original language
PHONY += descend $(build-dirs)
descend: $(build-dirs)
$(build-dirs): prepare
	$(Q)$(MAKE) $(build)=$@ \
	single-build=$(if $(filter-out $@/, $(filter $@/%, $(KBUILD_SINGLE_TARGETS))),1) \
	need-builtin=1 need-modorder=1

clean-dirs := $(addprefix _clean_, $(clean-dirs))
PHONY += $(clean-dirs) clean
$(clean-dirs):
	$(Q)$(MAKE) $(clean)=$(patsubst _clean_%,%,$@)

clean: $(clean-dirs)
	$(call cmd,rmfiles)
	@find $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
		\( -name '*.[aios]' -o -name '*.ko' -o -name '.*.cmd' \
		-o -name '*.ko.*' \
		-o -name '*.dtb' -o -name '*.dtbo' -o -name '*.dtb.S' -o -name '*.dt.yaml' \
		-o -name '*.dwo' -o -name '*.lst' \
		-o -name '*.su' -o -name '*.mod' \
		-o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
		-o -name '*.lex.c' -o -name '*.tab.[ch]' \
		-o -name '*.asn1.[ch]' \
		-o -name '*.symtypes' -o -name 'modules.order' \
		-o -name '.tmp_*.o.*' \
		-o -name '*.c.[012]*.*' \
		-o -name '*.ll' \
		-o -name '*.gcno' \
		-o -name '*.*.symversions' \) -type f -print | xargs rm -f

# Generate tags for editors
# ---------------------------------------------------------------------------
quiet_cmd_tags = GEN     $@
      cmd_tags = $(BASH) $(srctree)/scripts/tags.sh $@

tags TAGS cscope gtags: FORCE
	$(call cmd,tags)

# Script to generate missing namespace dependencies
# ---------------------------------------------------------------------------

PHONY += nsdeps
nsdeps: export KBUILD_NSDEPS=1
nsdeps: modules
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/nsdeps

# Clang Tooling
# ---------------------------------------------------------------------------

quiet_cmd_gen_compile_commands = GEN     $@
      cmd_gen_compile_commands = $(PYTHON3) $< -a $(AR) -o $@ $(filter-out $<, $(real-prereqs))

$(extmod_prefix)compile_commands.json: scripts/clang-tools/gen_compile_commands.py \
	$(if $(KBUILD_EXTMOD),,$(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)) \
	$(if $(CONFIG_MODULES), $(MODORDER)) FORCE
	$(call if_changed,gen_compile_commands)

targets += $(extmod_prefix)compile_commands.json

PHONY += clang-tidy clang-analyzer

ifdef CONFIG_CC_IS_CLANG
quiet_cmd_clang_tools = CHECK   $<
      cmd_clang_tools = $(PYTHON3) $(srctree)/scripts/clang-tools/run-clang-tools.py $@ $<

clang-tidy clang-analyzer: $(extmod_prefix)compile_commands.json
	$(call cmd,clang_tools)
else
clang-tidy clang-analyzer:
	@echo "$@ requires CC=clang" >&2
	@false
endif

# Scripts to check various things for consistency
# ---------------------------------------------------------------------------

PHONY += includecheck versioncheck coccicheck export_report

includecheck:
	find $(srctree)/* $(RCS_FIND_IGNORE) \
		-name '*.[hcS]' -type f -print | sort \
		| xargs $(PERL) -w $(srctree)/scripts/checkincludes.pl

versioncheck:
	find $(srctree)/* $(RCS_FIND_IGNORE) \
		-name '*.[hcS]' -type f -print | sort \
		| xargs $(PERL) -w $(srctree)/scripts/checkversion.pl

coccicheck:
	$(Q)$(BASH) $(srctree)/scripts/$@

export_report:
	$(PERL) $(srctree)/scripts/export_report.pl

PHONY += checkstack kernelrelease kernelversion image_name

# UML needs a little special treatment here.  It wants to use the host
# toolchain, so needs $(SUBARCH) passed to checkstack.pl.  Everyone
# else wants $(ARCH), including people doing cross-builds, which means
# that $(SUBARCH) doesn't work here.
ifeq ($(ARCH), um)
CHECKSTACK_ARCH := $(SUBARCH)
else
CHECKSTACK_ARCH := $(ARCH)
endif
checkstack:
	$(OBJDUMP) -d vmlinux $$(find . -name '*.ko') | \
	$(PERL) $(srctree)/scripts/checkstack.pl $(CHECKSTACK_ARCH)

kernelrelease:
	@echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"

kernelversion:
	@echo $(KERNELVERSION)

image_name:
	@echo $(KBUILD_IMAGE)

quiet_cmd_rmfiles = $(if $(wildcard $(rm-files)),CLEAN   $(wildcard $(rm-files)))
      cmd_rmfiles = rm -rf $(rm-files)

# read saved command lines for existing targets
existing-targets := $(wildcard $(sort $(targets)))

-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)

endif # config-build
endif # mixed-build
endif # need-sub-make

PHONY += FORCE
FORCE:

# Declare the contents of the PHONY variable as phony.  We keep that
# information in a variable so we can use it in if_changed and friends.
.PHONY: $(PHONY)