# ===========================================================================# Module versions# ===========================================================================## Stage one of module building created the following:# a) The individual .o files used for the module# b) A <module>.o file which is the .o files above linked together# c) A <module>.mod file in $(MODVERDIR)/, listing the name of the#    the preliminary <module>.o file, plus all .o files # Stage 2 is handled by this file and does the following# 1) Find all modules from the files listed in $(MODVERDIR)/# 2) modpost is then used to# 3)  create one <module>.mod.c file pr. module# 4)  create one Module.symvers file with CRC for all exported symbols# 5) compile all <module>.mod.c files# 6) final link of the module to a <module.ko> file # Step 3 is used to place certain information in the module's ELF# section, including information such as:#   Version magic (see include/vermagic.h for full details)#     - Kernel release#     - SMP is CONFIG_SMP#     - PREEMPT is CONFIG_PREEMPT#     - GCC Version#   Module info#     - Module version (MODULE_VERSION)#     - Module alias'es (MODULE_ALIAS)#     - Module license (MODULE_LICENSE)#     - See include/linux/module.h for more details # Step 4 is solely used to allow module versioning in external modules,# where the CRC of each module is retrieved from the Module.symers file. PHONY := _modpost_modpost: __modpost include .configinclude scripts/Kbuild.includeinclude scripts/Makefile.lib kernelsymfile := $(objtree)/Module.symversmodulesymfile := $(KBUILD_EXTMOD)/Modules.symvers # Step 1), find all modules listed in $(MODVERDIR)/__modules := $(sort $(shell grep -h '\.ko' /dev/null $(wildcard $(MODVERDIR)/*.mod)))modules   := $(patsubst %.o,%.ko, $(wildcard $(__modules:.ko=.o))) _modpost: $(modules)  # Step 2), invoke modpost#  Includes step 3,4quiet_cmd_modpost = MODPOST      cmd_modpost = scripts/mod/modpost            \        $(if $(CONFIG_MODVERSIONS),-m)             \	$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a,)  \	$(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile) \	$(if $(KBUILD_EXTMOD),-I $(modulesymfile)) \	$(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \	$(filter-out FORCE,$^) PHONY += __modpost__modpost: $(wildcard vmlinux) $(modules:.ko=.o) FORCE	$(call cmd,modpost) # Declare generated files as targets for modpost$(symverfile):         __modpost ;$(modules:.ko=.mod.c): __modpost ;  # Step 5), compile all *.mod.c files # modname is set to make c_flags define KBUILD_MODNAMEmodname = $(*F) quiet_cmd_cc_o_c = CC      $@      cmd_cc_o_c = $(CC) $(c_flags) $(CFLAGS_MODULE)	\		   -c -o $@ $< $(modules:.ko=.mod.o): %.mod.o: %.mod.c FORCE	$(call if_changed_dep,cc_o_c) targets += $(modules:.ko=.mod.o) # Step 6), final link of the modulesquiet_cmd_ld_ko_o = LD [M]  $@      cmd_ld_ko_o = $(LD) $(LDFLAGS) $(LDFLAGS_MODULE) -o $@ 		\			  $(filter-out FORCE,$^) $(modules): %.ko :%.o %.mod.o FORCE	$(call if_changed,ld_ko_o) targets += $(modules)  # 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  # Declare the contents of the .PHONY variable as phony.  We keep that# information in a variable se we can use it in if_changed and friends. .PHONY: $(PHONY)