1 # SPDX-License-Identifier: GPL-2.0
2 # ===========================================================================
4 # ===========================================================================
6 # Stage one of module building created the following:
7 # a) The individual .o files used for the module
8 # b) A <module>.o file which is the .o files above linked together
9 # c) A <module>.mod file in $(MODVERDIR)/, listing the name of the
10 # the preliminary <module>.o file, plus all .o files
12 # Stage 2 is handled by this file and does the following
13 # 1) Find all modules from the files listed in $(MODVERDIR)/
14 # 2) modpost is then used to
15 # 3) create one <module>.mod.c file pr. module
16 # 4) create one Module.symvers file with CRC for all exported symbols
17 # 5) compile all <module>.mod.c files
18 # 6) final link of the module to a <module.ko> file
20 # Step 3 is used to place certain information in the module's ELF
21 # section, including information such as:
22 # Version magic (see include/linux/vermagic.h for full details)
25 # - PREEMPT is CONFIG_PREEMPT
28 # - Module version (MODULE_VERSION)
29 # - Module alias'es (MODULE_ALIAS)
30 # - Module license (MODULE_LICENSE)
31 # - See include/linux/module.h for more details
33 # Step 4 is solely used to allow module versioning in external modules,
34 # where the CRC of each module is retrieved from the Module.symvers file.
36 # KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined
37 # symbols in the final module linking stage
38 # KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
39 # This is solely useful to speed up test compiles
43 include include/config/auto.conf
44 include scripts/Kbuild.include
46 # When building external modules load the Kbuild file to retrieve EXTRA_SYMBOLS info
47 ifneq ($(KBUILD_EXTMOD),)
49 # set src + obj - they may be used when building the .mod.c file
50 obj := $(KBUILD_EXTMOD)
53 # Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS
54 include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \
55 $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)
58 include scripts/Makefile.lib
60 kernelsymfile := $(objtree)/Module.symvers
61 modulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers
63 # Step 1), find all modules listed in $(MODVERDIR)/
64 MODLISTCMD := find $(MODVERDIR) -name '*.mod' | xargs -r grep -h '\.ko$$' | sort -u
65 __modules := $(shell $(MODLISTCMD))
66 modules := $(patsubst %.o,%.ko, $(wildcard $(__modules:.ko=.o)))
68 # Stop after building .o files if NOFINAL is set. Makes compile tests quicker
69 _modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules))
71 # Step 2), invoke modpost
73 modpost = scripts/mod/modpost \
74 $(if $(CONFIG_MODVERSIONS),-m) \
75 $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a,) \
76 $(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile) \
77 $(if $(KBUILD_EXTMOD),-I $(modulesymfile)) \
78 $(if $(KBUILD_EXTRA_SYMBOLS), $(patsubst %, -e %,$(KBUILD_EXTRA_SYMBOLS))) \
79 $(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \
80 $(if $(CONFIG_DEBUG_SECTION_MISMATCH),,-S) \
81 $(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
82 $(if $(KBUILD_EXTMOD)$(KBUILD_MODPOST_WARN),-w)
84 MODPOST_OPT=$(subst -i,-n,$(filter -i,$(MAKEFLAGS)))
86 # We can go over command line length here, so be careful.
87 quiet_cmd_modpost = MODPOST $(words $(filter-out vmlinux FORCE, $^)) modules
88 cmd_modpost = $(MODLISTCMD) | sed 's/\.ko$$/.o/' | $(modpost) $(MODPOST_OPT) -s -T -
91 __modpost: $(modules:.ko=.o) FORCE
92 $(call cmd,modpost) $(wildcard vmlinux)
94 quiet_cmd_kernel-mod = MODPOST $@
95 cmd_kernel-mod = $(modpost) $@
98 $(call cmd,kernel-mod)
100 # Declare generated files as targets for modpost
101 $(modules:.ko=.mod.c): __modpost ;
104 # Step 5), compile all *.mod.c files
106 # modname is set to make c_flags define KBUILD_MODNAME
107 modname = $(notdir $(@:.mod.o=))
109 quiet_cmd_cc_o_c = CC $@
110 cmd_cc_o_c = $(CC) $(c_flags) $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE) \
113 $(modules:.ko=.mod.o): %.mod.o: %.mod.c FORCE
114 $(call if_changed_dep,cc_o_c)
116 targets += $(modules:.ko=.mod.o)
118 ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
120 # Step 6), final link of the modules with optional arch pass after final link
121 quiet_cmd_ld_ko_o = LD [M] $@
123 $(LD) -r $(LDFLAGS) \
124 $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
125 -o $@ $(filter-out FORCE,$^) ; \
126 $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
128 $(modules): %.ko :%.o %.mod.o FORCE
129 +$(call if_changed,ld_ko_o)
131 targets += $(modules)
134 # Add FORCE to the prequisites of a target to force it to be always rebuilt.
135 # ---------------------------------------------------------------------------
141 # Read all saved command lines and dependencies for the $(targets) we
142 # may be building above, using $(if_changed{,_dep}). As an
143 # optimization, we don't need to read them if the target does not
144 # exist, we will rebuild anyway in that case.
146 cmd_files := $(wildcard $(foreach f,$(sort $(targets)),$(dir $(f)).$(notdir $(f)).cmd))
148 ifneq ($(cmd_files),)
153 # Declare the contents of the .PHONY variable as phony. We keep that
154 # information in a variable se we can use it in if_changed and friends.