# SPDX-License-Identifier: GPL-2.0# ===========================================================================# 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, listing the name of the preliminary <module>.o file,#    plus all .o files# d) modules.order, which lists all the modules # Stage 2 is handled by this file and does the following# 1) Find all modules listed in modules.order# 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/linux/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.symvers file. # KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined# symbols in the final module linking stage# KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.# This is solely useful to speed up test compilesPHONY := _modpost_modpost: __modpost include include/config/auto.confinclude scripts/Kbuild.include # When building external modules load the Kbuild file to retrieve EXTRA_SYMBOLS infoifneq ($(KBUILD_EXTMOD),) # set src + obj - they may be used when building the .mod.c fileobj := $(KBUILD_EXTMOD)src := $(obj) # Include the module's Makefile to find KBUILD_EXTRA_SYMBOLSinclude $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \             $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)endif include scripts/Makefile.lib kernelsymfile := $(objtree)/Module.symversmodulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers modorder := $(if $(KBUILD_EXTMOD),$(KBUILD_EXTMOD)/)modules.order # Step 1), find all modules listed in modules.orderifdef CONFIG_MODULESmodules := $(sort $(shell cat $(modorder)))endif # Stop after building .o files if NOFINAL is set. Makes compile tests quicker_modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules)) # Step 2), invoke modpost#  Includes step 3,4modpost = 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_EXTRA_SYMBOLS), $(patsubst %, -e %,$(KBUILD_EXTRA_SYMBOLS))) \ $(if $(KBUILD_EXTMOD),-o $(modulesymfile))      \ $(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E)  \ $(if $(KBUILD_MODPOST_WARN),-w) MODPOST_OPT=$(subst -i,-n,$(filter -i,$(MAKEFLAGS))) # We can go over command line length here, so be careful.quiet_cmd_modpost = MODPOST $(words $(filter-out vmlinux FORCE, $^)) modules      cmd_modpost = sed 's/ko$$/o/' $(modorder) | $(modpost) $(MODPOST_OPT) -s -T - PHONY += __modpost__modpost: $(modules:.ko=.o) FORCE	$(call cmd,modpost) $(wildcard vmlinux) quiet_cmd_kernel-mod = MODPOST $@      cmd_kernel-mod = $(modpost) $@ vmlinux.o: FORCE	$(call cmd,kernel-mod) # Declare generated files as targets for modpost$(modules:.ko=.mod.c): __modpost ;  # Step 5), compile all *.mod.c files # modname is set to make c_flags define KBUILD_MODNAMEmodname = $(notdir $(@:.mod.o=)) quiet_cmd_cc_o_c = CC      $@      cmd_cc_o_c = $(CC) $(c_flags) $(KBUILD_CFLAGS_MODULE) $(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) ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink) # Step 6), final link of the modules with optional arch pass after final linkquiet_cmd_ld_ko_o = LD [M]  $@      cmd_ld_ko_o =                                                     \	$(LD) -r $(KBUILD_LDFLAGS)                                      \                 $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE)             \                 -o $@ $(real-prereqs) ;                                \	$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true) $(modules): %.ko :%.o %.mod.o FORCE	+$(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. cmd_files := $(wildcard $(foreach f,$(sort $(targets)),$(dir $(f)).$(notdir $(f)).cmd)) ifneq ($(cmd_files),)  include $(cmd_files)endif .PHONY: $(PHONY)