xref: /openbmc/linux/scripts/Makefile.modpost (revision 137bfbd0) 
1# SPDX-License-Identifier: GPL-2.0
2# ===========================================================================
3# Module versions
4# ===========================================================================
5#
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, listing the name of the preliminary <module>.o file,
10#    plus all .o files
11# d) modules.order, which lists all the modules
12
13# Stage 2 is handled by this file and does the following
14# 1) Find all modules listed in modules.order
15# 2) modpost is then used to
16# 3)  create one <module>.mod.c file pr. module
17# 4)  create one Module.symvers file with CRC for all exported symbols
18# 5) compile all <module>.mod.c files
19# 6) final link of the module to a <module.ko> file
20
21# Step 3 is used to place certain information in the module's ELF
22# section, including information such as:
23#   Version magic (see include/linux/vermagic.h for full details)
24#     - Kernel release
25#     - SMP is CONFIG_SMP
26#     - PREEMPT is CONFIG_PREEMPT
27#     - GCC Version
28#   Module info
29#     - Module version (MODULE_VERSION)
30#     - Module alias'es (MODULE_ALIAS)
31#     - Module license (MODULE_LICENSE)
32#     - See include/linux/module.h for more details
33
34# Step 4 is solely used to allow module versioning in external modules,
35# where the CRC of each module is retrieved from the Module.symvers file.
36
37# KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined
38# symbols in the final module linking stage
39# KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
40# This is solely useful to speed up test compiles
41
42PHONY := __modpost
43__modpost:
44
45include include/config/auto.conf
46include scripts/Kbuild.include
47
48kernelsymfile := $(objtree)/Module.symvers
49modulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers
50
51MODPOST = scripts/mod/modpost						\
52	$(if $(CONFIG_MODVERSIONS),-m)					\
53	$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a)			\
54	$(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile)			\
55	$(if $(KBUILD_EXTMOD),-I $(modulesymfile))			\
56	$(if $(KBUILD_EXTMOD),$(addprefix -e ,$(KBUILD_EXTRA_SYMBOLS)))	\
57	$(if $(KBUILD_EXTMOD),-o $(modulesymfile))			\
58	$(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E)			\
59	$(if $(KBUILD_MODPOST_WARN),-w)
60
61ifdef MODPOST_VMLINUX
62
63__modpost: vmlinux.o
64
65quiet_cmd_modpost = MODPOST $@
66      cmd_modpost = $(MODPOST) $@
67
68PHONY += vmlinux.o
69vmlinux.o:
70	$(call cmd,modpost)
71
72else
73
74# When building external modules load the Kbuild file to retrieve EXTRA_SYMBOLS info
75ifneq ($(KBUILD_EXTMOD),)
76
77# set src + obj - they may be used when building the .mod.c file
78obj := $(KBUILD_EXTMOD)
79src := $(obj)
80
81# Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS
82include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \
83             $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)
84endif
85
86include scripts/Makefile.lib
87
88# find all modules listed in modules.order
89modules := $(sort $(shell cat $(MODORDER)))
90
91# Stop after building .o files if NOFINAL is set. Makes compile tests quicker
92__modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules))
93	@:
94
95MODPOST += $(subst -i,-n,$(filter -i,$(MAKEFLAGS))) -s -T - $(wildcard vmlinux)
96
97# We can go over command line length here, so be careful.
98quiet_cmd_modpost = MODPOST $(words $(modules)) modules
99      cmd_modpost = sed 's/ko$$/o/' $(MODORDER) | $(MODPOST)
100
101PHONY += modules-modpost
102modules-modpost:
103	$(call cmd,modpost)
104
105# Declare generated files as targets for modpost
106$(modules:.ko=.mod.c): modules-modpost
107
108# Step 5), compile all *.mod.c files
109
110# modname is set to make c_flags define KBUILD_MODNAME
111modname = $(notdir $(@:.mod.o=))
112
113quiet_cmd_cc_o_c = CC      $@
114      cmd_cc_o_c = $(CC) $(c_flags) $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE) \
115		   -c -o $@ $<
116
117$(modules:.ko=.mod.o): %.mod.o: %.mod.c FORCE
118	$(call if_changed_dep,cc_o_c)
119
120targets += $(modules:.ko=.mod.o)
121
122ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
123
124# Step 6), final link of the modules with optional arch pass after final link
125quiet_cmd_ld_ko_o = LD [M]  $@
126      cmd_ld_ko_o =                                                     \
127	$(LD) -r $(KBUILD_LDFLAGS)                                      \
128                 $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE)             \
129                 -o $@ $(real-prereqs) ;                                \
130	$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
131
132$(modules): %.ko :%.o %.mod.o FORCE
133	+$(call if_changed,ld_ko_o)
134
135targets += $(modules)
136
137
138# Add FORCE to the prequisites of a target to force it to be always rebuilt.
139# ---------------------------------------------------------------------------
140
141PHONY += FORCE
142
143FORCE:
144
145# Read all saved command lines and dependencies for the $(targets) we
146# may be building above, using $(if_changed{,_dep}). As an
147# optimization, we don't need to read them if the target does not
148# exist, we will rebuild anyway in that case.
149
150existing-targets := $(wildcard $(sort $(targets)))
151
152-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
153
154endif
155
156.PHONY: $(PHONY)
157