# 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 compiles PHONY := _modpost _modpost: __modpost include include/config/auto.conf include scripts/Kbuild.include # When building external modules load the Kbuild file to retrieve EXTRA_SYMBOLS info ifneq ($(KBUILD_EXTMOD),) # set src + obj - they may be used when building the .mod.c file obj := $(KBUILD_EXTMOD) src := $(obj) # Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \ $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile) endif include scripts/Makefile.lib kernelsymfile := $(objtree)/Module.symvers modulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers modorder := $(if $(KBUILD_EXTMOD),$(KBUILD_EXTMOD)/)modules.order # Step 1), find all modules listed in modules.order ifdef CONFIG_MODULES modules := $(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 3,4 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_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_MODNAME modname = $(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 link quiet_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)