scripts/Makefile.build - third_party/kernel - Git at Google


            
            # SPDX-License-Identifier: GPL-2.0

            
            # ==========================================================================

            
            # Building

            
            # ==========================================================================


            src := $(obj)


            PHONY := $(obj)/

            
            $(obj)/:


            # Init all relevant variables used in kbuild files so

            
            # 1) they have correct type

            
            # 2) they do not inherit any value from the environment

            
            obj-y :=

            
            obj-m :=

            
            lib-y :=

            
            lib-m :=

            
            always-y :=

            
            always-m :=

            
            targets :=

            
            subdir-y :=

            
            subdir-m :=

            
            EXTRA_AFLAGS   :=

            
            EXTRA_CFLAGS   :=

            
            EXTRA_CPPFLAGS :=

            
            EXTRA_LDFLAGS  :=

            
            asflags-y  :=

            
            ccflags-y  :=

            
            rustflags-y :=

            
            cppflags-y :=

            
            ldflags-y  :=


            subdir-asflags-y :=

            
            subdir-ccflags-y :=


            # Read auto.conf if it exists, otherwise ignore

            
            -include include/config/auto.conf


            include $(srctree)/scripts/Kbuild.include

            
            include $(srctree)/scripts/Makefile.compiler

            
            include $(kbuild-file)

            
            include $(srctree)/scripts/Makefile.lib


            # Do not include hostprogs rules unless needed.

            
            # $(sort ...) is used here to remove duplicated words and excessive spaces.

            
            hostprogs := $(sort $(hostprogs))

            
            ifneq ($(hostprogs),)

            
            include $(srctree)/scripts/Makefile.host

            
            endif


            # Do not include userprogs rules unless needed.

            
            # $(sort ...) is used here to remove duplicated words and excessive spaces.

            
            userprogs := $(sort $(userprogs))

            
            ifneq ($(userprogs),)

            
            include $(srctree)/scripts/Makefile.userprogs

            
            endif


            ifndef obj

            
            $(warning kbuild: Makefile.build is included improperly)

            
            endif


            ifeq ($(need-modorder),)

            
            ifneq ($(obj-m),)

            
            $(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.)

            
            $(warning You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.)

            
            endif

            
            endif


            # ===========================================================================


            # subdir-builtin and subdir-modorder may contain duplications. Use $(sort ...)

            
            subdir-builtin := $(sort $(filter %/built-in.a, $(real-obj-y)))

            
            subdir-modorder := $(sort $(filter %/modules.order, $(obj-m)))


            targets-for-builtin := $(extra-y)


            ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)

            
            targets-for-builtin += $(obj)/lib.a

            
            endif


            ifdef need-builtin

            
            targets-for-builtin += $(obj)/built-in.a

            
            endif


            targets-for-modules := $(foreach x, o mod, \

            
            				$(patsubst %.o, %.$x, $(filter %.o, $(obj-m))))


            ifdef need-modorder

            
            targets-for-modules += $(obj)/modules.order

            
            endif


            targets += $(targets-for-builtin) $(targets-for-modules)


            # Linus' kernel sanity checking tool

            
            ifeq ($(KBUILD_CHECKSRC),1)

            
              quiet_cmd_checksrc       = CHECK   $<

            
                    cmd_checksrc       = $(CHECK) $(CHECKFLAGS) $(c_flags) $<

            
            else ifeq ($(KBUILD_CHECKSRC),2)

            
              quiet_cmd_force_checksrc = CHECK   $<

            
                    cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<

            
            endif


            ifneq ($(KBUILD_EXTRA_WARN),)

            
              cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $(KDOCFLAGS) \

            
                    $(if $(findstring 2, $(KBUILD_EXTRA_WARN)), -Wall) \

            
                    $<

            
            endif


            # Compile C sources (.c)

            
            # ---------------------------------------------------------------------------


            quiet_cmd_cc_s_c = CC $(quiet_modtag)  $@

            
                  cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS) $(CC_FLAGS_LTO), $(c_flags)) -fverbose-asm -S -o $@ $<


            $(obj)/%.s: $(src)/%.c FORCE

            
            	$(call if_changed_dep,cc_s_c)


            quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@

            
            cmd_cpp_i_c       = $(CPP) $(c_flags) -o $@ $<


            $(obj)/%.i: $(src)/%.c FORCE

            
            	$(call if_changed_dep,cpp_i_c)


            genksyms = scripts/genksyms/genksyms		\

            
            	$(if $(1), -T $(2))			\

            
            	$(if $(KBUILD_PRESERVE), -p)		\

            
            	-r $(or $(wildcard $(2:.symtypes=.symref)), /dev/null)


            # These mirror gensymtypes_S and co below, keep them in synch.

            
            cmd_gensymtypes_c = $(CPP) -D__GENKSYMS__ $(c_flags) $< | $(genksyms)


            quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@

            
                  cmd_cc_symtypes_c = $(call cmd_gensymtypes_c,true,$@) >/dev/null


            $(obj)/%.symtypes : $(src)/%.c FORCE

            
            	$(call cmd,cc_symtypes_c)


            # LLVM assembly

            
            # Generate .ll files from .c

            
            quiet_cmd_cc_ll_c = CC $(quiet_modtag)  $@

            
                  cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -fno-discard-value-names -o $@ $<


            $(obj)/%.ll: $(src)/%.c FORCE

            
            	$(call if_changed_dep,cc_ll_c)


            # C (.c) files

            
            # The C file is compiled and updated dependency information is generated.

            
            # (See cmd_cc_o_c + relevant part of rule_cc_o_c)


            is-single-obj-m = $(and $(part-of-module),$(filter $@, $(obj-m)),y)


            # When a module consists of a single object, there is no reason to keep LLVM IR.

            
            # Make $(LD) covert LLVM IR to ELF here.

            
            ifdef CONFIG_LTO_CLANG

            
            cmd_ld_single_m = $(if $(is-single-obj-m), ; $(LD) $(ld_flags) -r -o $(tmp-target) $@; mv $(tmp-target) $@)

            
            endif


            quiet_cmd_cc_o_c = CC $(quiet_modtag)  $@

            
                  cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< \

            
            		$(cmd_ld_single_m) \

            
            		$(cmd_objtool)


            ifdef CONFIG_MODVERSIONS

            
            # When module versioning is enabled the following steps are executed:

            
            # o compile a <file>.o from <file>.c

            
            # o if <file>.o doesn't contain a __export_symbol_*, i.e. does

            
            #   not export symbols, it's done.

            
            # o otherwise, we calculate symbol versions using the good old

            
            #   genksyms on the preprocessed source and dump them into the .cmd file.

            
            # o modpost will extract versions from that file and create *.c files that will

            
            #   be compiled and linked to the kernel and/or modules.


            gen_symversions =								\

            
            	if $(NM) $@ 2>/dev/null | grep -q ' __export_symbol_'; then		\

            
            		$(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \

            
            			>> $(dot-target).cmd;					\

            
            	fi


            cmd_gen_symversions_c =	$(call gen_symversions,c)


            endif


            ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT

            
            # compiler will not generate __mcount_loc use recordmcount or recordmcount.pl

            
            ifdef BUILD_C_RECORDMCOUNT

            
            ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")

            
              RECORDMCOUNT_FLAGS = -w

            
            endif

            
            # Due to recursion, we must skip empty.o.

            
            # The empty.o file is created in the make process in order to determine

            
            # the target endianness and word size. It is made before all other C

            
            # files, including recordmcount.

            
            sub_cmd_record_mcount =					\

            
            	if [ $(@) != "scripts/mod/empty.o" ]; then	\

            
            		$(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)";	\

            
            	fi;

            
            recordmcount_source := $(srctree)/scripts/recordmcount.c \

            
            		    $(srctree)/scripts/recordmcount.h

            
            else

            
            sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \

            
            	"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \

            
            	"$(if $(CONFIG_64BIT),64,32)" \

            
            	"$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \

            
            	"$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \

            
            	"$(if $(part-of-module),1,0)" "$(@)";

            
            recordmcount_source := $(srctree)/scripts/recordmcount.pl

            
            endif # BUILD_C_RECORDMCOUNT

            
            cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)),	\

            
            	$(sub_cmd_record_mcount))

            
            endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT


            # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory

            
            # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file

            
            # 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file


            is-standard-object = $(if $(filter-out y%, $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y)


            $(obj)/%.o: objtool-enabled = $(if $(is-standard-object),$(if $(delay-objtool),$(is-single-obj-m),y))


            ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)

            
            cmd_warn_shared_object = $(if $(word 2, $(modname-multi)),$(warning $(kbuild-file): $*.o is added to multiple modules: $(modname-multi)))

            
            endif


            define rule_cc_o_c

            
            	$(call cmd_and_fixdep,cc_o_c)

            
            	$(call cmd,checksrc)

            
            	$(call cmd,checkdoc)

            
            	$(call cmd,gen_objtooldep)

            
            	$(call cmd,gen_symversions_c)

            
            	$(call cmd,record_mcount)

            
            	$(call cmd,warn_shared_object)

            
            endef


            define rule_as_o_S

            
            	$(call cmd_and_fixdep,as_o_S)

            
            	$(call cmd,gen_objtooldep)

            
            	$(call cmd,gen_symversions_S)

            
            	$(call cmd,warn_shared_object)

            
            endef


            # Built-in and composite module parts

            
            $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE

            
            	$(call if_changed_rule,cc_o_c)

            
            	$(call cmd,force_checksrc)


            # To make this rule robust against "Argument list too long" error,

            
            # ensure to add $(obj)/ prefix by a shell command.

            
            cmd_mod = printf '%s\n' $(call real-search, $*.o, .o, -objs -y -m) | \

            
            	$(AWK) '!x[$$0]++ { print("$(obj)/"$$0) }' > $@


            $(obj)/%.mod: FORCE

            
            	$(call if_changed,mod)


            quiet_cmd_cc_lst_c = MKLST   $@

            
                  cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \

            
            		     $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \

            
            				     System.map $(OBJDUMP) > $@


            $(obj)/%.lst: $(src)/%.c FORCE

            
            	$(call if_changed_dep,cc_lst_c)


            # Compile Rust sources (.rs)

            
            # ---------------------------------------------------------------------------


            rust_allowed_features := new_uninit


            # `--out-dir` is required to avoid temporaries being created by `rustc` in the

            
            # current working directory, which may be not accessible in the out-of-tree

            
            # modules case.

            
            rust_common_cmd = \

            
            	RUST_MODFILE=$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \

            
            	-Zallow-features=$(rust_allowed_features) \

            
            	-Zcrate-attr=no_std \

            
            	-Zcrate-attr='feature($(rust_allowed_features))' \

            
            	-Zunstable-options --extern force:alloc --extern kernel \

            
            	--crate-type rlib -L $(objtree)/rust/ \

            
            	--crate-name $(basename $(notdir $@)) \

            
            	--out-dir $(dir $@) --emit=dep-info=$(depfile)


            # `--emit=obj`, `--emit=asm` and `--emit=llvm-ir` imply a single codegen unit

            
            # will be used. We explicitly request `-Ccodegen-units=1` in any case, and

            
            # the compiler shows a warning if it is not 1. However, if we ever stop

            
            # requesting it explicitly and we start using some other `--emit` that does not

            
            # imply it (and for which codegen is performed), then we would be out of sync,

            
            # i.e. the outputs we would get for the different single targets (e.g. `.ll`)

            
            # would not match each other.


            quiet_cmd_rustc_o_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@

            
                  cmd_rustc_o_rs = $(rust_common_cmd) --emit=obj=$@ $<


            $(obj)/%.o: $(src)/%.rs FORCE

            
            	$(call if_changed_dep,rustc_o_rs)


            quiet_cmd_rustc_rsi_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@

            
                  cmd_rustc_rsi_rs = \

            
            	$(rust_common_cmd) -Zunpretty=expanded $< >$@; \

            
            	command -v $(RUSTFMT) >/dev/null && $(RUSTFMT) --config-path $(srctree)/.rustfmt.toml $@


            $(obj)/%.rsi: $(src)/%.rs FORCE

            
            	$(call if_changed_dep,rustc_rsi_rs)


            quiet_cmd_rustc_s_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@

            
                  cmd_rustc_s_rs = $(rust_common_cmd) --emit=asm=$@ $<


            $(obj)/%.s: $(src)/%.rs FORCE

            
            	$(call if_changed_dep,rustc_s_rs)


            quiet_cmd_rustc_ll_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@

            
                  cmd_rustc_ll_rs = $(rust_common_cmd) --emit=llvm-ir=$@ $<


            $(obj)/%.ll: $(src)/%.rs FORCE

            
            	$(call if_changed_dep,rustc_ll_rs)


            # Compile assembler sources (.S)

            
            # ---------------------------------------------------------------------------


            # .S file exports must have their C prototypes defined in asm/asm-prototypes.h

            
            # or a file that it includes, in order to get versioned symbols. We build a

            
            # dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from

            
            # the .S file (with trailing ';'), and run genksyms on that, to extract vers.

            
            #

            
            # This is convoluted. The .S file must first be preprocessed to run guards and

            
            # expand names, then the resulting exports must be constructed into plain

            
            # EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed

            
            # to make the genksyms input.

            
            #

            
            # These mirror gensymtypes_c and co above, keep them in synch.

            
            cmd_gensymtypes_S =                                                         \

            
               { echo "\#include <linux/kernel.h>" ;                                    \

            
                 echo "\#include <asm/asm-prototypes.h>" ;                              \

            
                 $(NM) $@ | sed -n 's/.* __export_symbol_\(.*\)/EXPORT_SYMBOL(\1);/p' ; } | \

            
                $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | $(genksyms)


            quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@

            
                  cmd_cc_symtypes_S = $(call cmd_gensymtypes_S,true,$@) >/dev/null


            $(obj)/%.symtypes : $(src)/%.S FORCE

            
            	$(call cmd,cc_symtypes_S)


            quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@

            
            cmd_cpp_s_S       = $(CPP) $(a_flags) -o $@ $<


            $(obj)/%.s: $(src)/%.S FORCE

            
            	$(call if_changed_dep,cpp_s_S)


            quiet_cmd_as_o_S = AS $(quiet_modtag)  $@

            
                  cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $< $(cmd_objtool)


            ifdef CONFIG_ASM_MODVERSIONS


            # versioning matches the C process described above, with difference that

            
            # we parse asm-prototypes.h C header to get function definitions.


            cmd_gen_symversions_S = $(call gen_symversions,S)


            endif


            $(obj)/%.o: $(src)/%.S FORCE

            
            	$(call if_changed_rule,as_o_S)


            targets += $(filter-out $(subdir-builtin), $(real-obj-y))

            
            targets += $(filter-out $(subdir-modorder), $(real-obj-m))

            
            targets += $(real-dtb-y) $(lib-y) $(always-y)


            # Linker scripts preprocessor (.lds.S -> .lds)

            
            # ---------------------------------------------------------------------------

            
            quiet_cmd_cpp_lds_S = LDS     $@

            
                  cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \

            
            	                     -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<


            $(obj)/%.lds: $(src)/%.lds.S FORCE

            
            	$(call if_changed_dep,cpp_lds_S)


            # ASN.1 grammar

            
            # ---------------------------------------------------------------------------

            
            quiet_cmd_asn1_compiler = ASN.1   $(basename $@).[ch]

            
                  cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \

            
            				$(basename $@).c $(basename $@).h


            $(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler

            
            	$(call cmd,asn1_compiler)


            # Build the compiled-in targets

            
            # ---------------------------------------------------------------------------


            # To build objects in subdirs, we need to descend into the directories

            
            $(subdir-builtin): $(obj)/%/built-in.a: $(obj)/% ;

            
            $(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ;


            #

            
            # Rule to compile a set of .o files into one .a file (without symbol table)

            
            #

            
            # To make this rule robust against "Argument list too long" error,

            
            # remove $(obj)/ prefix, and restore it by a shell command.


            quiet_cmd_ar_builtin = AR      $@

            
                  cmd_ar_builtin = rm -f $@; \

            
            	$(if $(real-prereqs), printf "$(obj)/%s " $(patsubst $(obj)/%,%,$(real-prereqs)) | xargs) \

            
            	$(AR) cDPrST $@


            $(obj)/built-in.a: $(real-obj-y) FORCE

            
            	$(call if_changed,ar_builtin)


            #

            
            # Rule to create modules.order file

            
            #

            
            # Create commands to either record .ko file or cat modules.order from

            
            # a subdirectory

            
            # Add $(obj-m) as the prerequisite to avoid updating the timestamp of

            
            # modules.order unless contained modules are updated.


            cmd_modules_order = { $(foreach m, $(real-prereqs), \

            
            	$(if $(filter %/modules.order, $m), cat $m, echo $m);) :; } \

            
            	> $@


            $(obj)/modules.order: $(obj-m) FORCE

            
            	$(call if_changed,modules_order)


            #

            
            # Rule to compile a set of .o files into one .a file (with symbol table)

            
            #


            $(obj)/lib.a: $(lib-y) FORCE

            
            	$(call if_changed,ar)


            quiet_cmd_ld_multi_m = LD [M]  $@

            
                  cmd_ld_multi_m = $(LD) $(ld_flags) -r -o $@ @$(patsubst %.o,%.mod,$@) $(cmd_objtool)


            define rule_ld_multi_m

            
            	$(call cmd_and_savecmd,ld_multi_m)

            
            	$(call cmd,gen_objtooldep)

            
            endef


            $(multi-obj-m): objtool-enabled := $(delay-objtool)

            
            $(multi-obj-m): part-of-module := y

            
            $(multi-obj-m): %.o: %.mod FORCE

            
            	$(call if_changed_rule,ld_multi_m)

            
            $(call multi_depend, $(multi-obj-m), .o, -objs -y -m)


            # Add intermediate targets:

            
            # When building objects with specific suffix patterns, add intermediate

            
            # targets that the final targets are derived from.

            
            intermediate_targets = $(foreach sfx, $(2), \

            
            				$(patsubst %$(strip $(1)),%$(sfx), \

            
            					$(filter %$(strip $(1)), $(targets))))

            
            # %.asn1.o <- %.asn1.[ch] <- %.asn1

            
            # %.dtb.o <- %.dtb.S <- %.dtb <- %.dts

            
            # %.dtbo.o <- %.dtbo.S <- %.dtbo <- %.dtso

            
            # %.lex.o <- %.lex.c <- %.l

            
            # %.tab.o <- %.tab.[ch] <- %.y

            
            targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \

            
            	   $(call intermediate_targets, .dtb.o, .dtb.S .dtb) \

            
            	   $(call intermediate_targets, .dtbo.o, .dtbo.S .dtbo) \

            
            	   $(call intermediate_targets, .lex.o, .lex.c) \

            
            	   $(call intermediate_targets, .tab.o, .tab.c .tab.h)


            # Build

            
            # ---------------------------------------------------------------------------


            $(obj)/: $(if $(KBUILD_BUILTIN), $(targets-for-builtin)) \

            
            	 $(if $(KBUILD_MODULES), $(targets-for-modules)) \

            
            	 $(subdir-ym) $(always-y)

            
            	@:


            # Single targets

            
            # ---------------------------------------------------------------------------


            single-subdirs := $(foreach d, $(subdir-ym), $(if $(filter $d/%, $(MAKECMDGOALS)), $d))

            
            single-subdir-goals := $(filter $(addsuffix /%, $(single-subdirs)), $(MAKECMDGOALS))


            $(single-subdir-goals): $(single-subdirs)

            
            	@:


            # Descending

            
            # ---------------------------------------------------------------------------


            PHONY += $(subdir-ym)

            
            $(subdir-ym):

            
            	$(Q)$(MAKE) $(build)=$@ \

            
            	need-builtin=$(if $(filter $@/built-in.a, $(subdir-builtin)),1) \

            
            	need-modorder=$(if $(filter $@/modules.order, $(subdir-modorder)),1) \

            
            	$(filter $@/%, $(single-subdir-goals))


            # Add FORCE to the prequisites of a target to force it to be always rebuilt.

            
            # ---------------------------------------------------------------------------


            PHONY += FORCE


            FORCE:


            targets += $(filter-out $(single-subdir-goals), $(MAKECMDGOALS))

            
            targets := $(filter-out $(PHONY), $(targets))


            # Read all saved command lines and dependencies for the $(targets) we

            
            # may be building above, using $(if_changed{,_dep}). As an

            
            # optimization, we don't need to read them if the target does not

            
            # exist, we will rebuild anyway in that case.


            existing-targets := $(wildcard $(sort $(targets)))


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


            # Create directories for object files if they do not exist

            
            obj-dirs := $(sort $(patsubst %/,%, $(dir $(targets))))

            
            # If targets exist, their directories apparently exist. Skip mkdir.

            
            existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))

            
            obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))

            
            ifneq ($(obj-dirs),)

            
            $(shell mkdir -p $(obj-dirs))

            
            endif


            .PHONY: $(PHONY)
	# SPDX-License-Identifier: GPL-2.0
	# ==========================================================================
	# Building
	# ==========================================================================

	src := $(obj)

	PHONY := $(obj)/
	$(obj)/:

	# Init all relevant variables used in kbuild files so
	# 1) they have correct type
	# 2) they do not inherit any value from the environment
	obj-y :=
	obj-m :=
	lib-y :=
	lib-m :=
	always-y :=
	always-m :=
	targets :=
	subdir-y :=
	subdir-m :=
	EXTRA_AFLAGS :=
	EXTRA_CFLAGS :=
	EXTRA_CPPFLAGS :=
	EXTRA_LDFLAGS :=
	asflags-y :=
	ccflags-y :=
	rustflags-y :=
	cppflags-y :=
	ldflags-y :=

	subdir-asflags-y :=
	subdir-ccflags-y :=

	# Read auto.conf if it exists, otherwise ignore
	-include include/config/auto.conf

	include $(srctree)/scripts/Kbuild.include
	include $(srctree)/scripts/Makefile.compiler
	include $(kbuild-file)
	include $(srctree)/scripts/Makefile.lib

	# Do not include hostprogs rules unless needed.
	# $(sort ...) is used here to remove duplicated words and excessive spaces.
	hostprogs := $(sort $(hostprogs))
	ifneq ($(hostprogs),)
	include $(srctree)/scripts/Makefile.host
	endif

	# Do not include userprogs rules unless needed.
	# $(sort ...) is used here to remove duplicated words and excessive spaces.
	userprogs := $(sort $(userprogs))
	ifneq ($(userprogs),)
	include $(srctree)/scripts/Makefile.userprogs
	endif

	ifndef obj
	$(warning kbuild: Makefile.build is included improperly)
	endif

	ifeq ($(need-modorder),)
	ifneq ($(obj-m),)
	$(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.)
	$(warning You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.)
	endif
	endif

	# ===========================================================================

	# subdir-builtin and subdir-modorder may contain duplications. Use $(sort ...)
	subdir-builtin := $(sort $(filter %/built-in.a, $(real-obj-y)))
	subdir-modorder := $(sort $(filter %/modules.order, $(obj-m)))

	targets-for-builtin := $(extra-y)

	ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
	targets-for-builtin += $(obj)/lib.a
	endif

	ifdef need-builtin
	targets-for-builtin += $(obj)/built-in.a
	endif

	targets-for-modules := $(foreach x, o mod, \
	$(patsubst %.o, %.$x, $(filter %.o, $(obj-m))))

	ifdef need-modorder
	targets-for-modules += $(obj)/modules.order
	endif

	targets += $(targets-for-builtin) $(targets-for-modules)

	# Linus' kernel sanity checking tool
	ifeq ($(KBUILD_CHECKSRC),1)
	quiet_cmd_checksrc = CHECK $<
	cmd_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
	else ifeq ($(KBUILD_CHECKSRC),2)
	quiet_cmd_force_checksrc = CHECK $<
	cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
	endif

	ifneq ($(KBUILD_EXTRA_WARN),)
	cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $(KDOCFLAGS) \
	$(if $(findstring 2, $(KBUILD_EXTRA_WARN)), -Wall) \
	$<
	endif

	# Compile C sources (.c)
	# ---------------------------------------------------------------------------

	quiet_cmd_cc_s_c = CC $(quiet_modtag) $@
	cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS) $(CC_FLAGS_LTO), $(c_flags)) -fverbose-asm -S -o $@ $<

	$(obj)/%.s: $(src)/%.c FORCE
	$(call if_changed_dep,cc_s_c)

	quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
	cmd_cpp_i_c = $(CPP) $(c_flags) -o $@ $<

	$(obj)/%.i: $(src)/%.c FORCE
	$(call if_changed_dep,cpp_i_c)

	genksyms = scripts/genksyms/genksyms \
	$(if $(1), -T $(2)) \
	$(if $(KBUILD_PRESERVE), -p) \
	-r $(or $(wildcard $(2:.symtypes=.symref)), /dev/null)

	# These mirror gensymtypes_S and co below, keep them in synch.
	cmd_gensymtypes_c = $(CPP) -D__GENKSYMS__ $(c_flags) $< \| $(genksyms)

	quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
	cmd_cc_symtypes_c = $(call cmd_gensymtypes_c,true,$@) >/dev/null

	$(obj)/%.symtypes : $(src)/%.c FORCE
	$(call cmd,cc_symtypes_c)

	# LLVM assembly
	# Generate .ll files from .c
	quiet_cmd_cc_ll_c = CC $(quiet_modtag) $@
	cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -fno-discard-value-names -o $@ $<

	$(obj)/%.ll: $(src)/%.c FORCE
	$(call if_changed_dep,cc_ll_c)

	# C (.c) files
	# The C file is compiled and updated dependency information is generated.
	# (See cmd_cc_o_c + relevant part of rule_cc_o_c)

	is-single-obj-m = $(and $(part-of-module),$(filter $@, $(obj-m)),y)

	# When a module consists of a single object, there is no reason to keep LLVM IR.
	# Make $(LD) covert LLVM IR to ELF here.
	ifdef CONFIG_LTO_CLANG
	cmd_ld_single_m = $(if $(is-single-obj-m), ; $(LD) $(ld_flags) -r -o $(tmp-target) $@; mv $(tmp-target) $@)
	endif

	quiet_cmd_cc_o_c = CC $(quiet_modtag) $@
	cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< \
	$(cmd_ld_single_m) \
	$(cmd_objtool)

	ifdef CONFIG_MODVERSIONS
	# When module versioning is enabled the following steps are executed:
	# o compile a <file>.o from <file>.c
	# o if <file>.o doesn't contain a __export_symbol_*, i.e. does
	# not export symbols, it's done.
	# o otherwise, we calculate symbol versions using the good old
	# genksyms on the preprocessed source and dump them into the .cmd file.
	# o modpost will extract versions from that file and create *.c files that will
	# be compiled and linked to the kernel and/or modules.

	gen_symversions = \
	if $(NM) $@ 2>/dev/null \| grep -q ' __export_symbol_'; then \
	$(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
	>> $(dot-target).cmd; \
	fi

	cmd_gen_symversions_c = $(call gen_symversions,c)

	endif

	ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
	# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
	ifdef BUILD_C_RECORDMCOUNT
	ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
	RECORDMCOUNT_FLAGS = -w
	endif
	# Due to recursion, we must skip empty.o.
	# The empty.o file is created in the make process in order to determine
	# the target endianness and word size. It is made before all other C
	# files, including recordmcount.
	sub_cmd_record_mcount = \
	if [ $(@) != "scripts/mod/empty.o" ]; then \
	$(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
	fi;
	recordmcount_source := $(srctree)/scripts/recordmcount.c \
	$(srctree)/scripts/recordmcount.h
	else
	sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
	"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
	"$(if $(CONFIG_64BIT),64,32)" \
	"$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
	"$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
	"$(if $(part-of-module),1,0)" "$(@)";
	recordmcount_source := $(srctree)/scripts/recordmcount.pl
	endif # BUILD_C_RECORDMCOUNT
	cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), \
	$(sub_cmd_record_mcount))
	endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT

	# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
	# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
	# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file

	is-standard-object = $(if $(filter-out y%, $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y)

	$(obj)/%.o: objtool-enabled = $(if $(is-standard-object),$(if $(delay-objtool),$(is-single-obj-m),y))

	ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
	cmd_warn_shared_object = $(if $(word 2, $(modname-multi)),$(warning $(kbuild-file): $*.o is added to multiple modules: $(modname-multi)))
	endif

	define rule_cc_o_c
	$(call cmd_and_fixdep,cc_o_c)
	$(call cmd,checksrc)
	$(call cmd,checkdoc)
	$(call cmd,gen_objtooldep)
	$(call cmd,gen_symversions_c)
	$(call cmd,record_mcount)
	$(call cmd,warn_shared_object)
	endef

	define rule_as_o_S
	$(call cmd_and_fixdep,as_o_S)
	$(call cmd,gen_objtooldep)
	$(call cmd,gen_symversions_S)
	$(call cmd,warn_shared_object)
	endef

	# Built-in and composite module parts
	$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
	$(call if_changed_rule,cc_o_c)
	$(call cmd,force_checksrc)

	# To make this rule robust against "Argument list too long" error,
	# ensure to add $(obj)/ prefix by a shell command.
	cmd_mod = printf '%s\n' $(call real-search, $*.o, .o, -objs -y -m) \| \
	$(AWK) '!x[$$0]++ { print("$(obj)/"$$0) }' > $@

	$(obj)/%.mod: FORCE
	$(call if_changed,mod)

	quiet_cmd_cc_lst_c = MKLST $@
	cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
	$(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
	System.map $(OBJDUMP) > $@

	$(obj)/%.lst: $(src)/%.c FORCE
	$(call if_changed_dep,cc_lst_c)

	# Compile Rust sources (.rs)
	# ---------------------------------------------------------------------------

	rust_allowed_features := new_uninit

	# `--out-dir` is required to avoid temporaries being created by `rustc` in the
	# current working directory, which may be not accessible in the out-of-tree
	# modules case.
	rust_common_cmd = \
	RUST_MODFILE=$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \
	-Zallow-features=$(rust_allowed_features) \
	-Zcrate-attr=no_std \
	-Zcrate-attr='feature($(rust_allowed_features))' \
	-Zunstable-options --extern force:alloc --extern kernel \
	--crate-type rlib -L $(objtree)/rust/ \
	--crate-name $(basename $(notdir $@)) \
	--out-dir $(dir $@) --emit=dep-info=$(depfile)

	# `--emit=obj`, `--emit=asm` and `--emit=llvm-ir` imply a single codegen unit
	# will be used. We explicitly request `-Ccodegen-units=1` in any case, and
	# the compiler shows a warning if it is not 1. However, if we ever stop
	# requesting it explicitly and we start using some other `--emit` that does not
	# imply it (and for which codegen is performed), then we would be out of sync,
	# i.e. the outputs we would get for the different single targets (e.g. `.ll`)
	# would not match each other.

	quiet_cmd_rustc_o_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
	cmd_rustc_o_rs = $(rust_common_cmd) --emit=obj=$@ $<

	$(obj)/%.o: $(src)/%.rs FORCE
	$(call if_changed_dep,rustc_o_rs)

	quiet_cmd_rustc_rsi_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
	cmd_rustc_rsi_rs = \
	$(rust_common_cmd) -Zunpretty=expanded $< >$@; \
	command -v $(RUSTFMT) >/dev/null && $(RUSTFMT) --config-path $(srctree)/.rustfmt.toml $@

	$(obj)/%.rsi: $(src)/%.rs FORCE
	$(call if_changed_dep,rustc_rsi_rs)

	quiet_cmd_rustc_s_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
	cmd_rustc_s_rs = $(rust_common_cmd) --emit=asm=$@ $<

	$(obj)/%.s: $(src)/%.rs FORCE
	$(call if_changed_dep,rustc_s_rs)

	quiet_cmd_rustc_ll_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
	cmd_rustc_ll_rs = $(rust_common_cmd) --emit=llvm-ir=$@ $<

	$(obj)/%.ll: $(src)/%.rs FORCE
	$(call if_changed_dep,rustc_ll_rs)

	# Compile assembler sources (.S)
	# ---------------------------------------------------------------------------

	# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
	# or a file that it includes, in order to get versioned symbols. We build a
	# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
	# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
	#
	# This is convoluted. The .S file must first be preprocessed to run guards and
	# expand names, then the resulting exports must be constructed into plain
	# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
	# to make the genksyms input.
	#
	# These mirror gensymtypes_c and co above, keep them in synch.
	cmd_gensymtypes_S = \
	{ echo "\#include <linux/kernel.h>" ; \
	echo "\#include <asm/asm-prototypes.h>" ; \
	$(NM) $@ \| sed -n 's/.* __export_symbol_\(.*\)/EXPORT_SYMBOL(\1);/p' ; } \| \
	$(CPP) -D__GENKSYMS__ $(c_flags) -xc - \| $(genksyms)

	quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
	cmd_cc_symtypes_S = $(call cmd_gensymtypes_S,true,$@) >/dev/null

	$(obj)/%.symtypes : $(src)/%.S FORCE
	$(call cmd,cc_symtypes_S)


	quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
	cmd_cpp_s_S = $(CPP) $(a_flags) -o $@ $<

	$(obj)/%.s: $(src)/%.S FORCE
	$(call if_changed_dep,cpp_s_S)

	quiet_cmd_as_o_S = AS $(quiet_modtag) $@
	cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $< $(cmd_objtool)

	ifdef CONFIG_ASM_MODVERSIONS

	# versioning matches the C process described above, with difference that
	# we parse asm-prototypes.h C header to get function definitions.

	cmd_gen_symversions_S = $(call gen_symversions,S)

	endif

	$(obj)/%.o: $(src)/%.S FORCE
	$(call if_changed_rule,as_o_S)

	targets += $(filter-out $(subdir-builtin), $(real-obj-y))
	targets += $(filter-out $(subdir-modorder), $(real-obj-m))
	targets += $(real-dtb-y) $(lib-y) $(always-y)

	# Linker scripts preprocessor (.lds.S -> .lds)
	# ---------------------------------------------------------------------------
	quiet_cmd_cpp_lds_S = LDS $@
	cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
	-D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<

	$(obj)/%.lds: $(src)/%.lds.S FORCE
	$(call if_changed_dep,cpp_lds_S)

	# ASN.1 grammar
	# ---------------------------------------------------------------------------
	quiet_cmd_asn1_compiler = ASN.1 $(basename $@).[ch]
	cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
	$(basename $@).c $(basename $@).h

	$(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
	$(call cmd,asn1_compiler)

	# Build the compiled-in targets
	# ---------------------------------------------------------------------------

	# To build objects in subdirs, we need to descend into the directories
	$(subdir-builtin): $(obj)/%/built-in.a: $(obj)/% ;
	$(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ;

	#
	# Rule to compile a set of .o files into one .a file (without symbol table)
	#
	# To make this rule robust against "Argument list too long" error,
	# remove $(obj)/ prefix, and restore it by a shell command.

	quiet_cmd_ar_builtin = AR $@
	cmd_ar_builtin = rm -f $@; \
	$(if $(real-prereqs), printf "$(obj)/%s " $(patsubst $(obj)/%,%,$(real-prereqs)) \| xargs) \
	$(AR) cDPrST $@

	$(obj)/built-in.a: $(real-obj-y) FORCE
	$(call if_changed,ar_builtin)

	#
	# Rule to create modules.order file
	#
	# Create commands to either record .ko file or cat modules.order from
	# a subdirectory
	# Add $(obj-m) as the prerequisite to avoid updating the timestamp of
	# modules.order unless contained modules are updated.

	cmd_modules_order = { $(foreach m, $(real-prereqs), \
	$(if $(filter %/modules.order, $m), cat $m, echo $m);) :; } \
	> $@

	$(obj)/modules.order: $(obj-m) FORCE
	$(call if_changed,modules_order)

	#
	# Rule to compile a set of .o files into one .a file (with symbol table)
	#

	$(obj)/lib.a: $(lib-y) FORCE
	$(call if_changed,ar)

	quiet_cmd_ld_multi_m = LD [M] $@
	cmd_ld_multi_m = $(LD) $(ld_flags) -r -o $@ @$(patsubst %.o,%.mod,$@) $(cmd_objtool)

	define rule_ld_multi_m
	$(call cmd_and_savecmd,ld_multi_m)
	$(call cmd,gen_objtooldep)
	endef

	$(multi-obj-m): objtool-enabled := $(delay-objtool)
	$(multi-obj-m): part-of-module := y
	$(multi-obj-m): %.o: %.mod FORCE
	$(call if_changed_rule,ld_multi_m)
	$(call multi_depend, $(multi-obj-m), .o, -objs -y -m)

	# Add intermediate targets:
	# When building objects with specific suffix patterns, add intermediate
	# targets that the final targets are derived from.
	intermediate_targets = $(foreach sfx, $(2), \
	$(patsubst %$(strip $(1)),%$(sfx), \
	$(filter %$(strip $(1)), $(targets))))
	# %.asn1.o <- %.asn1.[ch] <- %.asn1
	# %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
	# %.dtbo.o <- %.dtbo.S <- %.dtbo <- %.dtso
	# %.lex.o <- %.lex.c <- %.l
	# %.tab.o <- %.tab.[ch] <- %.y
	targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
	$(call intermediate_targets, .dtb.o, .dtb.S .dtb) \
	$(call intermediate_targets, .dtbo.o, .dtbo.S .dtbo) \
	$(call intermediate_targets, .lex.o, .lex.c) \
	$(call intermediate_targets, .tab.o, .tab.c .tab.h)

	# Build
	# ---------------------------------------------------------------------------

	$(obj)/: $(if $(KBUILD_BUILTIN), $(targets-for-builtin)) \
	$(if $(KBUILD_MODULES), $(targets-for-modules)) \
	$(subdir-ym) $(always-y)
	@:

	# Single targets
	# ---------------------------------------------------------------------------

	single-subdirs := $(foreach d, $(subdir-ym), $(if $(filter $d/%, $(MAKECMDGOALS)), $d))
	single-subdir-goals := $(filter $(addsuffix /%, $(single-subdirs)), $(MAKECMDGOALS))

	$(single-subdir-goals): $(single-subdirs)
	@:

	# Descending
	# ---------------------------------------------------------------------------

	PHONY += $(subdir-ym)
	$(subdir-ym):
	$(Q)$(MAKE) $(build)=$@ \
	need-builtin=$(if $(filter $@/built-in.a, $(subdir-builtin)),1) \
	need-modorder=$(if $(filter $@/modules.order, $(subdir-modorder)),1) \
	$(filter $@/%, $(single-subdir-goals))

	# Add FORCE to the prequisites of a target to force it to be always rebuilt.
	# ---------------------------------------------------------------------------

	PHONY += FORCE

	FORCE:

	targets += $(filter-out $(single-subdir-goals), $(MAKECMDGOALS))
	targets := $(filter-out $(PHONY), $(targets))

	# Read all saved command lines and dependencies for the $(targets) we
	# may be building above, using $(if_changed{,_dep}). As an
	# optimization, we don't need to read them if the target does not
	# exist, we will rebuild anyway in that case.

	existing-targets := $(wildcard $(sort $(targets)))

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

	# Create directories for object files if they do not exist
	obj-dirs := $(sort $(patsubst %/,%, $(dir $(targets))))
	# If targets exist, their directories apparently exist. Skip mkdir.
	existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))
	obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))
	ifneq ($(obj-dirs),)
	$(shell mkdir -p $(obj-dirs))
	endif

	.PHONY: $(PHONY)