scripts/Makefile.build - pub/scm/linux/kernel/git/joro/linux - Git at Google

 # ==========================================================================
 # Building
 # ==========================================================================

 src := $(obj)

 .PHONY: __build
 __build:

 ifdef include_config
 include .config
 endif

 include $(obj)/Makefile

 include scripts/Makefile.lib

 ifdef EXTRA_TARGETS
 $(warning kbuild: $(obj)/Makefile - Usage of EXTRA_TARGETS is obsolete in 2.5. Please fix!)
 endif

 ifdef build-targets
 $(warning kbuild: $(obj)/Makefile - Usage of build-targets is obsolete in 2.5. Please fix!)
 endif

 ifdef export-objs
 $(warning kbuild: $(obj)/Makefile - Usage of export-objs is obsolete in 2.5. Please fix!)
 endif

 ifdef O_TARGET
 $(warning kbuild: $(obj)/Makefile - Usage of O_TARGET := $(O_TARGET) is obsolete in 2.5. Please fix!)
 endif

 ifdef L_TARGET
 ifneq ($(L_TARGET),lib.a)
 $(warning kbuild: $(obj)/Makefile - L_TARGET := $(L_TARGET) target shall be renamed to lib.a. Please fix!)
 endif
 endif

 ifdef list-multi
 $(warning kbuild: $(obj)/Makefile - list-multi := $(list-multi) is obsolete in 2.5. Please fix!)
 endif

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

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

 # If a Makefile does not define a L_TARGET, link an object called "built-in.o"

 ifdef L_TARGET
 L_TARGET := $(obj)/$(L_TARGET)
 else
 ifneq ($(strip $(obj-y) $(obj-m) $(obj-n) $(obj-)),)
 O_TARGET := $(obj)/built-in.o
 endif
 endif

 # We keep a list of all modules in $(MODVERDIR)

 touch-module = @echo $(@:.o=.ko) > $(MODVERDIR)/$(@F:.o=.mod)

 __build: $(if $(KBUILD_BUILTIN),$(O_TARGET) $(L_TARGET) $(extra-y)) \
 	 $(if $(KBUILD_MODULES),$(obj-m)) \
 	 $(subdir-ym) $(always)
 	@:

 # Module versioning
 # ---------------------------------------------------------------------------

 ifdef CONFIG_MODVERSIONS

 # $(call if_changed_rule,vcc_o_c) does essentially the same as the
 # normal $(call if_changed_dep,cc_o_c), i.e. compile an object file
 # from a C file, keeping track of the command line and dependencies.
 #
 # However, actually it does:
 # o compile a .tmp_<file>.o from <file>.c
 # o if .tmp_<file>.o doesn't contain a __ksymtab version, i.e. does
 #   not export symbols, we just rename .tmp_<file>.o to <file>.o and
 #   are done.
 # o otherwise, we calculate symbol versions using the good old
 #   genksyms on the preprocessed source and postprocess them in a way
 #   that they are usable as a linker script
 # o generate <file>.o from .tmp_<file>.o using the linker to
 #   replace the unresolved symbols __crc_exported_symbol with
 #   the actual value of the checksum generated by genksyms

 quiet_cmd_vcc_o_c = CC $(quiet_modtag)  $@
 cmd_vcc_o_c       = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $<

 define rule_vcc_o_c
 	$(if $($(quiet)cmd_vcc_o_c),echo '  $($(quiet)cmd_vcc_o_c)';)	      \
 	$(cmd_vcc_o_c);							      \
 									      \
 	if ! $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then	      \
 		mv $(@D)/.tmp_$(@F) $@;					      \
 	else								      \
 		$(CPP) -D__GENKSYMS__ $(c_flags) $<			      \
 		| $(GENKSYMS)						      \
 		> $(@D)/.tmp_$(@F:.o=.ver);				      \
 									      \
 		$(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) 		      \
 			-T $(@D)/.tmp_$(@F:.o=.ver);			      \
 		rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver);	      \
 	fi;
 					      \
 	scripts/fixdep $(depfile) $@ '$(cmd_vcc_o_c)' > $(@D)/.$(@F).tmp;     \
 	rm -f $(depfile);						      \
 	mv -f $(@D)/.$(@F).tmp $(@D)/.$(@F).cmd
 endef

 endif

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

 # Default is built-in, unless we know otherwise
 modkern_cflags := $(CFLAGS_KERNEL)
 quiet_modtag := $(empty)   $(empty)

 $(real-objs-m)        : modkern_cflags := $(CFLAGS_MODULE)
 $(real-objs-m:.o=.i)  : modkern_cflags := $(CFLAGS_MODULE)
 $(real-objs-m:.o=.s)  : modkern_cflags := $(CFLAGS_MODULE)
 $(real-objs-m:.o=.lst): modkern_cflags := $(CFLAGS_MODULE)

 $(real-objs-m)        : quiet_modtag := [M]
 $(real-objs-m:.o=.i)  : quiet_modtag := [M]
 $(real-objs-m:.o=.s)  : quiet_modtag := [M]
 $(real-objs-m:.o=.lst): quiet_modtag := [M]

 $(obj-m)              : quiet_modtag := [M]

 # Default for not multi-part modules
 modname = $(*F)

 $(multi-objs-m)         : modname = $(modname-multi)
 $(multi-objs-m:.o=.i)   : modname = $(modname-multi)
 $(multi-objs-m:.o=.s)   : modname = $(modname-multi)
 $(multi-objs-m:.o=.lst) : modname = $(modname-multi)
 $(multi-objs-y)         : modname = $(modname-multi)
 $(multi-objs-y:.o=.i)   : modname = $(modname-multi)
 $(multi-objs-y:.o=.s)   : modname = $(modname-multi)
 $(multi-objs-y:.o=.lst) : modname = $(modname-multi)

 quiet_cmd_cc_s_c = CC $(quiet_modtag)  $@
 cmd_cc_s_c       = $(CC) $(c_flags) -S -o $@ $<

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

 quiet_cmd_cc_i_c = CPP $(quiet_modtag) $@
 cmd_cc_i_c       = $(CPP) $(c_flags)   -o $@ $<

 %.i: %.c FORCE
 	$(call if_changed_dep,cc_i_c)

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

 # Built-in and composite module parts

 %.o: %.c FORCE
 ifdef CONFIG_MODVERSIONS
 	$(call if_changed_rule,vcc_o_c)
 else
 	$(call if_changed_dep,cc_o_c)
 endif

 # Single-part modules are special since we need to mark them in $(MODVERDIR)

 $(single-used-m): %.o: %.c FORCE
 ifdef CONFIG_MODVERSIONS
 	$(call if_changed_rule,vcc_o_c)
 else
 	$(call if_changed_dep,cc_o_c)
 endif
 	$(touch-module)

 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) > $@

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

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

 modkern_aflags := $(AFLAGS_KERNEL)

 $(real-objs-m)      : modkern_aflags := $(AFLAGS_MODULE)
 $(real-objs-m:.o=.s): modkern_aflags := $(AFLAGS_MODULE)

 quiet_cmd_as_s_S = CPP $(quiet_modtag) $@
 cmd_as_s_S       = $(CPP) $(a_flags)   -o $@ $<

 %.s: %.S FORCE
 	$(call if_changed_dep,as_s_S)

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

 %.o: %.S FORCE
 	$(call if_changed_dep,as_o_S)

 targets += $(real-objs-y) $(real-objs-m) $(extra-y) $(MAKECMDGOALS) $(always)

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

 # To build objects in subdirs, we need to descend into the directories
 $(sort $(subdir-obj-y)): $(subdir-ym) ;

 #
 # Rule to compile a set of .o files into one .o file
 #
 ifdef O_TARGET
 quiet_cmd_link_o_target = LD      $@
 # If the list of objects to link is empty, just create an empty O_TARGET
 cmd_link_o_target = $(if $(strip $(obj-y)),\
 		      $(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^),\
 		      rm -f $@; $(AR) rcs $@)

 $(O_TARGET): $(obj-y) FORCE
 	$(call if_changed,link_o_target)

 targets += $(O_TARGET)
 endif # O_TARGET

 #
 # Rule to compile a set of .o files into one .a file
 #
 ifdef L_TARGET
 quiet_cmd_link_l_target = AR      $@
 cmd_link_l_target = rm -f $@; $(AR) $(EXTRA_ARFLAGS) rcs $@ $(obj-y)

 $(L_TARGET): $(obj-y) FORCE
 	$(call if_changed,link_l_target)

 targets += $(L_TARGET)
 endif

 #
 # Rule to link composite objects
 #
 #  Composite objects are specified in kbuild makefile as follows:
 #    <composite-object>-objs := <list of .o files>
 #  or
 #    <composite-object>-y    := <list of .o files>
 link_multi_deps =                     \
 $(filter $(addprefix $(obj)/,         \
 $($(subst $(obj)/,,$(@:.o=-objs)))    \
 $($(subst $(obj)/,,$(@:.o=-y)))), $^)

 quiet_cmd_link_multi-y = LD      $@
 cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps)

 quiet_cmd_link_multi-m = LD [M]  $@
 cmd_link_multi-m = $(LD) $(ld_flags) $(LDFLAGS_MODULE) -o $@ $(link_multi_deps)

 # We would rather have a list of rules like
 # 	foo.o: $(foo-objs)
 # but that's not so easy, so we rather make all composite objects depend
 # on the set of all their parts
 $(multi-used-y) : %.o: $(multi-objs-y) FORCE
 	$(call if_changed,link_multi-y)

 $(multi-used-m) : %.o: $(multi-objs-m) FORCE
 	$(call if_changed,link_multi-m)
 	$(touch-module)

 targets += $(multi-used-y) $(multi-used-m)

 # Compile programs on the host
 # ===========================================================================
 # host-progs := bin2hex
 # Will compile bin2hex.c and create an executable named bin2hex
 #
 # host-progs    := lxdialog
 # lxdialog-objs := checklist.o lxdialog.o
 # Will compile lxdialog.c and checklist.c, and then link the executable
 # lxdialog, based on checklist.o and lxdialog.o
 #
 # host-progs      := qconf
 # qconf-cxxobjs   := qconf.o
 # qconf-objs      := menu.o
 # Will compile qconf as a C++ program, and menu as a C program.
 # They are linked as C++ code to the executable qconf

 # host-progs := conf
 # conf-objs  := conf.o libkconfig.so
 # libkconfig-objs := expr.o type.o
 # Will create a shared library named libkconfig.so that consist of
 # expr.o and type.o (they are both compiled as C code and the object file
 # are made as position independent code).
 # conf.c is compiled as a c program, and conf.o is linked together with
 # libkconfig.so as the executable conf.
 # Note: Shared libraries consisting of C++ files are not supported
 #

 # Create executable from a single .c file
 # host-csingle -> Executable
 quiet_cmd_host-csingle 	= HOSTCC  $@
       cmd_host-csingle	= $(HOSTCC) $(hostc_flags) $(HOST_LOADLIBES) -o $@ $<
 $(host-csingle): %: %.c FORCE
 	$(call if_changed_dep,host-csingle)

 # Link an executable based on list of .o files, all plain c
 # host-cmulti -> executable
 quiet_cmd_host-cmulti	= HOSTLD  $@
       cmd_host-cmulti	= $(HOSTCC) $(HOSTLDFLAGS) -o $@ \
 			  $(addprefix $(obj)/,$($(@F)-objs)) \
 			  $(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
 $(host-cmulti): %: $(host-cobjs) $(host-cshlib) FORCE
 	$(call if_changed,host-cmulti)

 # Create .o file from a single .c file
 # host-cobjs -> .o
 quiet_cmd_host-cobjs	= HOSTCC  $@
       cmd_host-cobjs	= $(HOSTCC) $(hostc_flags) -c -o $@ $<
 $(host-cobjs): %.o: %.c FORCE
 	$(call if_changed_dep,host-cobjs)

 # Link an executable based on list of .o files, a mixture of .c and .cc
 # host-cxxmulti -> executable
 quiet_cmd_host-cxxmulti	= HOSTLD  $@
       cmd_host-cxxmulti	= $(HOSTCXX) $(HOSTLDFLAGS) -o $@ \
 			  $(foreach o,objs cxxobjs,\
 			  $(addprefix $(obj)/,$($(@F)-$(o)))) \
 			  $(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
 $(host-cxxmulti): %: $(host-cobjs) $(host-cxxobjs) $(host-cshlib) FORCE
 	$(call if_changed,host-cxxmulti)

 # Create .o file from a single .cc (C++) file
 quiet_cmd_host-cxxobjs	= HOSTCXX $@
       cmd_host-cxxobjs	= $(HOSTCXX) $(hostcxx_flags) -c -o $@ $<
 $(host-cxxobjs): %.o: %.cc FORCE
 	$(call if_changed_dep,host-cxxobjs)

 # Compile .c file, create position independent .o file
 # host-cshobjs -> .o
 quiet_cmd_host-cshobjs	= HOSTCC  -fPIC $@
       cmd_host-cshobjs	= $(HOSTCC) $(hostc_flags) -fPIC -c -o $@ $<
 $(host-cshobjs): %.o: %.c FORCE
 	$(call if_changed_dep,host-cshobjs)

 # Link a shared library, based on position independent .o files
 # *.o -> .so shared library (host-cshlib)
 quiet_cmd_host-cshlib	= HOSTLLD -shared $@
       cmd_host-cshlib	= $(HOSTCC) $(HOSTLDFLAGS) -shared -o $@ \
 			  $(addprefix $(obj)/,$($(@F:.so=-objs))) \
 			  $(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
 $(host-cshlib): %: $(host-cshobjs) FORCE
 	$(call if_changed,host-cshlib)

 targets += $(host-csingle)  $(host-cmulti) $(host-cobjs)\
 	   $(host-cxxmulti) $(host-cxxobjs) $(host-cshlib) $(host-cshobjs)

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

 .PHONY: $(subdir-ym)
 $(subdir-ym):
 	$(Q)$(MAKE) $(build)=$@

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

 .PHONY: FORCE

 FORCE:

 # 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.

 targets := $(wildcard $(sort $(targets)))
 cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))

 ifneq ($(cmd_files),)
   include $(cmd_files)
 endif
	# ==========================================================================
	# Building
	# ==========================================================================

	src := $(obj)

	.PHONY: __build
	__build:

	ifdef include_config
	include .config
	endif

	include $(obj)/Makefile

	include scripts/Makefile.lib

	ifdef EXTRA_TARGETS
	$(warning kbuild: $(obj)/Makefile - Usage of EXTRA_TARGETS is obsolete in 2.5. Please fix!)
	endif

	ifdef build-targets
	$(warning kbuild: $(obj)/Makefile - Usage of build-targets is obsolete in 2.5. Please fix!)
	endif

	ifdef export-objs
	$(warning kbuild: $(obj)/Makefile - Usage of export-objs is obsolete in 2.5. Please fix!)
	endif

	ifdef O_TARGET
	$(warning kbuild: $(obj)/Makefile - Usage of O_TARGET := $(O_TARGET) is obsolete in 2.5. Please fix!)
	endif

	ifdef L_TARGET
	ifneq ($(L_TARGET),lib.a)
	$(warning kbuild: $(obj)/Makefile - L_TARGET := $(L_TARGET) target shall be renamed to lib.a. Please fix!)
	endif
	endif

	ifdef list-multi
	$(warning kbuild: $(obj)/Makefile - list-multi := $(list-multi) is obsolete in 2.5. Please fix!)
	endif

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

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

	# If a Makefile does not define a L_TARGET, link an object called "built-in.o"

	ifdef L_TARGET
	L_TARGET := $(obj)/$(L_TARGET)
	else
	ifneq ($(strip $(obj-y) $(obj-m) $(obj-n) $(obj-)),)
	O_TARGET := $(obj)/built-in.o
	endif
	endif

	# We keep a list of all modules in $(MODVERDIR)

	touch-module = @echo $(@:.o=.ko) > $(MODVERDIR)/$(@F:.o=.mod)

	__build: $(if $(KBUILD_BUILTIN),$(O_TARGET) $(L_TARGET) $(extra-y)) \
	$(if $(KBUILD_MODULES),$(obj-m)) \
	$(subdir-ym) $(always)
	@:

	# Module versioning
	# ---------------------------------------------------------------------------

	ifdef CONFIG_MODVERSIONS

	# $(call if_changed_rule,vcc_o_c) does essentially the same as the
	# normal $(call if_changed_dep,cc_o_c), i.e. compile an object file
	# from a C file, keeping track of the command line and dependencies.
	#
	# However, actually it does:
	# o compile a .tmp_<file>.o from <file>.c
	# o if .tmp_<file>.o doesn't contain a __ksymtab version, i.e. does
	# not export symbols, we just rename .tmp_<file>.o to <file>.o and
	# are done.
	# o otherwise, we calculate symbol versions using the good old
	# genksyms on the preprocessed source and postprocess them in a way
	# that they are usable as a linker script
	# o generate <file>.o from .tmp_<file>.o using the linker to
	# replace the unresolved symbols __crc_exported_symbol with
	# the actual value of the checksum generated by genksyms

	quiet_cmd_vcc_o_c = CC $(quiet_modtag) $@
	cmd_vcc_o_c = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $<

	define rule_vcc_o_c
	$(if $($(quiet)cmd_vcc_o_c),echo ' $($(quiet)cmd_vcc_o_c)';) \
	$(cmd_vcc_o_c); \
	\
	if ! $(OBJDUMP) -h $(@D)/.tmp_$(@F) \| grep -q __ksymtab; then \
	mv $(@D)/.tmp_$(@F) $@; \
	else \
	$(CPP) -D__GENKSYMS__ $(c_flags) $< \
	\| $(GENKSYMS) \
	> $(@D)/.tmp_$(@F:.o=.ver); \
	\
	$(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) \
	-T $(@D)/.tmp_$(@F:.o=.ver); \
	rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver); \
	fi;
	\
	scripts/fixdep $(depfile) $@ '$(cmd_vcc_o_c)' > $(@D)/.$(@F).tmp; \
	rm -f $(depfile); \
	mv -f $(@D)/.$(@F).tmp $(@D)/.$(@F).cmd
	endef

	endif

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

	# Default is built-in, unless we know otherwise
	modkern_cflags := $(CFLAGS_KERNEL)
	quiet_modtag := $(empty) $(empty)

	$(real-objs-m) : modkern_cflags := $(CFLAGS_MODULE)
	$(real-objs-m:.o=.i) : modkern_cflags := $(CFLAGS_MODULE)
	$(real-objs-m:.o=.s) : modkern_cflags := $(CFLAGS_MODULE)
	$(real-objs-m:.o=.lst): modkern_cflags := $(CFLAGS_MODULE)

	$(real-objs-m) : quiet_modtag := [M]
	$(real-objs-m:.o=.i) : quiet_modtag := [M]
	$(real-objs-m:.o=.s) : quiet_modtag := [M]
	$(real-objs-m:.o=.lst): quiet_modtag := [M]

	$(obj-m) : quiet_modtag := [M]

	# Default for not multi-part modules
	modname = $(*F)

	$(multi-objs-m) : modname = $(modname-multi)
	$(multi-objs-m:.o=.i) : modname = $(modname-multi)
	$(multi-objs-m:.o=.s) : modname = $(modname-multi)
	$(multi-objs-m:.o=.lst) : modname = $(modname-multi)
	$(multi-objs-y) : modname = $(modname-multi)
	$(multi-objs-y:.o=.i) : modname = $(modname-multi)
	$(multi-objs-y:.o=.s) : modname = $(modname-multi)
	$(multi-objs-y:.o=.lst) : modname = $(modname-multi)

	quiet_cmd_cc_s_c = CC $(quiet_modtag) $@
	cmd_cc_s_c = $(CC) $(c_flags) -S -o $@ $<

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

	quiet_cmd_cc_i_c = CPP $(quiet_modtag) $@
	cmd_cc_i_c = $(CPP) $(c_flags) -o $@ $<

	%.i: %.c FORCE
	$(call if_changed_dep,cc_i_c)

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

	# Built-in and composite module parts

	%.o: %.c FORCE
	ifdef CONFIG_MODVERSIONS
	$(call if_changed_rule,vcc_o_c)
	else
	$(call if_changed_dep,cc_o_c)
	endif

	# Single-part modules are special since we need to mark them in $(MODVERDIR)

	$(single-used-m): %.o: %.c FORCE
	ifdef CONFIG_MODVERSIONS
	$(call if_changed_rule,vcc_o_c)
	else
	$(call if_changed_dep,cc_o_c)
	endif
	$(touch-module)

	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) > $@

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

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

	modkern_aflags := $(AFLAGS_KERNEL)

	$(real-objs-m) : modkern_aflags := $(AFLAGS_MODULE)
	$(real-objs-m:.o=.s): modkern_aflags := $(AFLAGS_MODULE)

	quiet_cmd_as_s_S = CPP $(quiet_modtag) $@
	cmd_as_s_S = $(CPP) $(a_flags) -o $@ $<

	%.s: %.S FORCE
	$(call if_changed_dep,as_s_S)

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

	%.o: %.S FORCE
	$(call if_changed_dep,as_o_S)

	targets += $(real-objs-y) $(real-objs-m) $(extra-y) $(MAKECMDGOALS) $(always)

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

	# To build objects in subdirs, we need to descend into the directories
	$(sort $(subdir-obj-y)): $(subdir-ym) ;

	#
	# Rule to compile a set of .o files into one .o file
	#
	ifdef O_TARGET
	quiet_cmd_link_o_target = LD $@
	# If the list of objects to link is empty, just create an empty O_TARGET
	cmd_link_o_target = $(if $(strip $(obj-y)),\
	$(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^),\
	rm -f $@; $(AR) rcs $@)

	$(O_TARGET): $(obj-y) FORCE
	$(call if_changed,link_o_target)

	targets += $(O_TARGET)
	endif # O_TARGET

	#
	# Rule to compile a set of .o files into one .a file
	#
	ifdef L_TARGET
	quiet_cmd_link_l_target = AR $@
	cmd_link_l_target = rm -f $@; $(AR) $(EXTRA_ARFLAGS) rcs $@ $(obj-y)

	$(L_TARGET): $(obj-y) FORCE
	$(call if_changed,link_l_target)

	targets += $(L_TARGET)
	endif

	#
	# Rule to link composite objects
	#
	# Composite objects are specified in kbuild makefile as follows:
	# <composite-object>-objs := <list of .o files>
	# or
	# <composite-object>-y := <list of .o files>
	link_multi_deps = \
	$(filter $(addprefix $(obj)/, \
	$($(subst $(obj)/,,$(@:.o=-objs))) \
	$($(subst $(obj)/,,$(@:.o=-y)))), $^)

	quiet_cmd_link_multi-y = LD $@
	cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps)

	quiet_cmd_link_multi-m = LD [M] $@
	cmd_link_multi-m = $(LD) $(ld_flags) $(LDFLAGS_MODULE) -o $@ $(link_multi_deps)

	# We would rather have a list of rules like
	# foo.o: $(foo-objs)
	# but that's not so easy, so we rather make all composite objects depend
	# on the set of all their parts
	$(multi-used-y) : %.o: $(multi-objs-y) FORCE
	$(call if_changed,link_multi-y)

	$(multi-used-m) : %.o: $(multi-objs-m) FORCE
	$(call if_changed,link_multi-m)
	$(touch-module)

	targets += $(multi-used-y) $(multi-used-m)

	# Compile programs on the host
	# ===========================================================================
	# host-progs := bin2hex
	# Will compile bin2hex.c and create an executable named bin2hex
	#
	# host-progs := lxdialog
	# lxdialog-objs := checklist.o lxdialog.o
	# Will compile lxdialog.c and checklist.c, and then link the executable
	# lxdialog, based on checklist.o and lxdialog.o
	#
	# host-progs := qconf
	# qconf-cxxobjs := qconf.o
	# qconf-objs := menu.o
	# Will compile qconf as a C++ program, and menu as a C program.
	# They are linked as C++ code to the executable qconf

	# host-progs := conf
	# conf-objs := conf.o libkconfig.so
	# libkconfig-objs := expr.o type.o
	# Will create a shared library named libkconfig.so that consist of
	# expr.o and type.o (they are both compiled as C code and the object file
	# are made as position independent code).
	# conf.c is compiled as a c program, and conf.o is linked together with
	# libkconfig.so as the executable conf.
	# Note: Shared libraries consisting of C++ files are not supported
	#

	# Create executable from a single .c file
	# host-csingle -> Executable
	quiet_cmd_host-csingle = HOSTCC $@
	cmd_host-csingle = $(HOSTCC) $(hostc_flags) $(HOST_LOADLIBES) -o $@ $<
	$(host-csingle): %: %.c FORCE
	$(call if_changed_dep,host-csingle)

	# Link an executable based on list of .o files, all plain c
	# host-cmulti -> executable
	quiet_cmd_host-cmulti = HOSTLD $@
	cmd_host-cmulti = $(HOSTCC) $(HOSTLDFLAGS) -o $@ \
	$(addprefix $(obj)/,$($(@F)-objs)) \
	$(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
	$(host-cmulti): %: $(host-cobjs) $(host-cshlib) FORCE
	$(call if_changed,host-cmulti)

	# Create .o file from a single .c file
	# host-cobjs -> .o
	quiet_cmd_host-cobjs = HOSTCC $@
	cmd_host-cobjs = $(HOSTCC) $(hostc_flags) -c -o $@ $<
	$(host-cobjs): %.o: %.c FORCE
	$(call if_changed_dep,host-cobjs)

	# Link an executable based on list of .o files, a mixture of .c and .cc
	# host-cxxmulti -> executable
	quiet_cmd_host-cxxmulti = HOSTLD $@
	cmd_host-cxxmulti = $(HOSTCXX) $(HOSTLDFLAGS) -o $@ \
	$(foreach o,objs cxxobjs,\
	$(addprefix $(obj)/,$($(@F)-$(o)))) \
	$(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
	$(host-cxxmulti): %: $(host-cobjs) $(host-cxxobjs) $(host-cshlib) FORCE
	$(call if_changed,host-cxxmulti)

	# Create .o file from a single .cc (C++) file
	quiet_cmd_host-cxxobjs = HOSTCXX $@
	cmd_host-cxxobjs = $(HOSTCXX) $(hostcxx_flags) -c -o $@ $<
	$(host-cxxobjs): %.o: %.cc FORCE
	$(call if_changed_dep,host-cxxobjs)

	# Compile .c file, create position independent .o file
	# host-cshobjs -> .o
	quiet_cmd_host-cshobjs = HOSTCC -fPIC $@
	cmd_host-cshobjs = $(HOSTCC) $(hostc_flags) -fPIC -c -o $@ $<
	$(host-cshobjs): %.o: %.c FORCE
	$(call if_changed_dep,host-cshobjs)

	# Link a shared library, based on position independent .o files
	# *.o -> .so shared library (host-cshlib)
	quiet_cmd_host-cshlib = HOSTLLD -shared $@
	cmd_host-cshlib = $(HOSTCC) $(HOSTLDFLAGS) -shared -o $@ \
	$(addprefix $(obj)/,$($(@F:.so=-objs))) \
	$(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
	$(host-cshlib): %: $(host-cshobjs) FORCE
	$(call if_changed,host-cshlib)

	targets += $(host-csingle) $(host-cmulti) $(host-cobjs)\
	$(host-cxxmulti) $(host-cxxobjs) $(host-cshlib) $(host-cshobjs)

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

	.PHONY: $(subdir-ym)
	$(subdir-ym):
	$(Q)$(MAKE) $(build)=$@

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

	.PHONY: FORCE

	FORCE:

	# 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.

	targets := $(wildcard $(sort $(targets)))
	cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))

	ifneq ($(cmd_files),)
	include $(cmd_files)
	endif