xref: /openbmc/linux/scripts/Makefile.modpost (revision 4aea96f4) 
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 in $(MODVERDIR)/, listing the name of the
10#    the preliminary <module>.o file, plus all .o files
11
12# Stage 2 is handled by this file and does the following
13# 1) Find all modules from the files listed in $(MODVERDIR)/
14# 2) modpost is then used to
15# 3)  create one <module>.mod.c file pr. module
16# 4)  create one Module.symvers file with CRC for all exported symbols
17# 5) compile all <module>.mod.c files
18# 6) final link of the module to a <module.ko> file
19
20# Step 3 is used to place certain information in the module's ELF
21# section, including information such as:
22#   Version magic (see include/linux/vermagic.h for full details)
23#     - Kernel release
24#     - SMP is CONFIG_SMP
25#     - PREEMPT is CONFIG_PREEMPT
26#     - GCC Version
27#   Module info
28#     - Module version (MODULE_VERSION)
29#     - Module alias'es (MODULE_ALIAS)
30#     - Module license (MODULE_LICENSE)
31#     - See include/linux/module.h for more details
32
33# Step 4 is solely used to allow module versioning in external modules,
34# where the CRC of each module is retrieved from the Module.symvers file.
35
36# KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined
37# symbols in the final module linking stage
38# KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
39# This is solely useful to speed up test compiles
40PHONY := _modpost
41_modpost: __modpost
42
43include include/config/auto.conf
44include scripts/Kbuild.include
45
46# When building external modules load the Kbuild file to retrieve EXTRA_SYMBOLS info
47ifneq ($(KBUILD_EXTMOD),)
48
49# set src + obj - they may be used when building the .mod.c file
50obj := $(KBUILD_EXTMOD)
51src := $(obj)
52
53# Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS
54include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \
55             $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)
56endif
57
58include scripts/Makefile.lib
59
60kernelsymfile := $(objtree)/Module.symvers
61modulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers
62
63# Step 1), find all modules listed in $(MODVERDIR)/
64MODLISTCMD := find $(MODVERDIR) -name '*.mod' | xargs -r grep -h '\.ko$$' | sort -u
65__modules := $(shell $(MODLISTCMD))
66modules   := $(patsubst %.o,%.ko, $(wildcard $(__modules:.ko=.o)))
67
68# Stop after building .o files if NOFINAL is set. Makes compile tests quicker
69_modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules))
70
71# Step 2), invoke modpost
72#  Includes step 3,4
73modpost = scripts/mod/modpost                    \
74 $(if $(CONFIG_MODVERSIONS),-m)                  \
75 $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a,)       \
76 $(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile)   \
77 $(if $(KBUILD_EXTMOD),-I $(modulesymfile))      \
78 $(if $(KBUILD_EXTRA_SYMBOLS), $(patsubst %, -e %,$(KBUILD_EXTRA_SYMBOLS))) \
79 $(if $(KBUILD_EXTMOD),-o $(modulesymfile))      \
80 $(if $(CONFIG_DEBUG_SECTION_MISMATCH),,-S)      \
81 $(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E)  \
82 $(if $(KBUILD_EXTMOD)$(KBUILD_MODPOST_WARN),-w)
83
84MODPOST_OPT=$(subst -i,-n,$(filter -i,$(MAKEFLAGS)))
85
86# We can go over command line length here, so be careful.
87quiet_cmd_modpost = MODPOST $(words $(filter-out vmlinux FORCE, $^)) modules
88      cmd_modpost = $(MODLISTCMD) | sed 's/\.ko$$/.o/' | $(modpost) $(MODPOST_OPT) -s -T -
89
90PHONY += __modpost
91__modpost: $(modules:.ko=.o) FORCE
92	$(call cmd,modpost) $(wildcard vmlinux)
93
94quiet_cmd_kernel-mod = MODPOST $@
95      cmd_kernel-mod = $(modpost) $@
96
97vmlinux.o: FORCE
98	$(call cmd,kernel-mod)
99
100# Declare generated files as targets for modpost
101$(modules:.ko=.mod.c): __modpost ;
102
103
104# Step 5), compile all *.mod.c files
105
106# modname is set to make c_flags define KBUILD_MODNAME
107modname = $(notdir $(@:.mod.o=))
108
109quiet_cmd_cc_o_c = CC      $@
110      cmd_cc_o_c = $(CC) $(c_flags) $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE) \
111		   -c -o $@ $<
112
113$(modules:.ko=.mod.o): %.mod.o: %.mod.c FORCE
114	$(call if_changed_dep,cc_o_c)
115
116targets += $(modules:.ko=.mod.o)
117
118ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
119
120# Step 6), final link of the modules with optional arch pass after final link
121quiet_cmd_ld_ko_o = LD [M]  $@
122      cmd_ld_ko_o =                                                     \
123	$(LD) -r $(KBUILD_LDFLAGS)                                      \
124                 $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE)             \
125                 -o $@ $(filter-out FORCE,$^) ;                         \
126	$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
127
128$(modules): %.ko :%.o %.mod.o FORCE
129	+$(call if_changed,ld_ko_o)
130
131targets += $(modules)
132
133
134# Add FORCE to the prequisites of a target to force it to be always rebuilt.
135# ---------------------------------------------------------------------------
136
137PHONY += FORCE
138
139FORCE:
140
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.
145
146cmd_files := $(wildcard $(foreach f,$(sort $(targets)),$(dir $(f)).$(notdir $(f)).cmd))
147
148ifneq ($(cmd_files),)
149  include $(cmd_files)
150endif
151
152.PHONY: $(PHONY)
153