xref: /openbmc/linux/scripts/Makefile.modpost (revision a2cce7a9) 
1# ===========================================================================
2# Module versions
3# ===========================================================================
4#
5# Stage one of module building created the following:
6# a) The individual .o files used for the module
7# b) A <module>.o file which is the .o files above linked together
8# c) A <module>.mod file in $(MODVERDIR)/, listing the name of the
9#    the preliminary <module>.o file, plus all .o files
10
11# Stage 2 is handled by this file and does the following
12# 1) Find all modules from the files listed in $(MODVERDIR)/
13# 2) modpost is then used to
14# 3)  create one <module>.mod.c file pr. module
15# 4)  create one Module.symvers file with CRC for all exported symbols
16# 5) compile all <module>.mod.c files
17# 6) final link of the module to a <module.ko> file
18
19# Step 3 is used to place certain information in the module's ELF
20# section, including information such as:
21#   Version magic (see include/linux/vermagic.h for full details)
22#     - Kernel release
23#     - SMP is CONFIG_SMP
24#     - PREEMPT is CONFIG_PREEMPT
25#     - GCC Version
26#   Module info
27#     - Module version (MODULE_VERSION)
28#     - Module alias'es (MODULE_ALIAS)
29#     - Module license (MODULE_LICENSE)
30#     - See include/linux/module.h for more details
31
32# Step 4 is solely used to allow module versioning in external modules,
33# where the CRC of each module is retrieved from the Module.symvers file.
34
35# KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined
36# symbols in the final module linking stage
37# KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
38# This is solely useful to speed up test compiles
39PHONY := _modpost
40_modpost: __modpost
41
42include include/config/auto.conf
43include scripts/Kbuild.include
44
45# When building external modules load the Kbuild file to retrieve EXTRA_SYMBOLS info
46ifneq ($(KBUILD_EXTMOD),)
47
48# set src + obj - they may be used when building the .mod.c file
49obj := $(KBUILD_EXTMOD)
50src := $(obj)
51
52# Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS
53include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \
54             $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)
55endif
56
57include scripts/Makefile.lib
58
59kernelsymfile := $(objtree)/Module.symvers
60modulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers
61
62# Step 1), find all modules listed in $(MODVERDIR)/
63MODLISTCMD := find $(MODVERDIR) -name '*.mod' | xargs -r grep -h '\.ko$$' | sort -u
64__modules := $(shell $(MODLISTCMD))
65modules   := $(patsubst %.o,%.ko, $(wildcard $(__modules:.ko=.o)))
66
67# Stop after building .o files if NOFINAL is set. Makes compile tests quicker
68_modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules))
69
70# Step 2), invoke modpost
71#  Includes step 3,4
72modpost = scripts/mod/modpost                    \
73 $(if $(CONFIG_MODVERSIONS),-m)                  \
74 $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a,)       \
75 $(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile)   \
76 $(if $(KBUILD_EXTMOD),-I $(modulesymfile))      \
77 $(if $(KBUILD_EXTRA_SYMBOLS), $(patsubst %, -e %,$(KBUILD_EXTRA_SYMBOLS))) \
78 $(if $(KBUILD_EXTMOD),-o $(modulesymfile))      \
79 $(if $(CONFIG_DEBUG_SECTION_MISMATCH),,-S)      \
80 $(if $(KBUILD_EXTMOD)$(KBUILD_MODPOST_WARN),-w)
81
82MODPOST_OPT=$(subst -i,-n,$(filter -i,$(MAKEFLAGS)))
83
84# We can go over command line length here, so be careful.
85quiet_cmd_modpost = MODPOST $(words $(filter-out vmlinux FORCE, $^)) modules
86      cmd_modpost = $(MODLISTCMD) | sed 's/\.ko$$/.o/' | $(modpost) $(MODPOST_OPT) -s -T -
87
88PHONY += __modpost
89__modpost: $(modules:.ko=.o) FORCE
90	$(call cmd,modpost) $(wildcard vmlinux)
91
92quiet_cmd_kernel-mod = MODPOST $@
93      cmd_kernel-mod = $(modpost) $@
94
95vmlinux.o: FORCE
96	$(call cmd,kernel-mod)
97
98# Declare generated files as targets for modpost
99$(symverfile):         __modpost ;
100$(modules:.ko=.mod.c): __modpost ;
101
102
103# Step 5), compile all *.mod.c files
104
105# modname is set to make c_flags define KBUILD_MODNAME
106modname = $(notdir $(@:.mod.o=))
107
108quiet_cmd_cc_o_c = CC      $@
109      cmd_cc_o_c = $(CC) $(c_flags) $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE) \
110		   -c -o $@ $<
111
112$(modules:.ko=.mod.o): %.mod.o: %.mod.c FORCE
113	$(call if_changed_dep,cc_o_c)
114
115targets += $(modules:.ko=.mod.o)
116
117# Step 6), final link of the modules
118quiet_cmd_ld_ko_o = LD [M]  $@
119      cmd_ld_ko_o = $(LD) -r $(LDFLAGS)                                 \
120                             $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
121                             -o $@ $(filter-out FORCE,$^)
122
123$(modules): %.ko :%.o %.mod.o FORCE
124	$(call if_changed,ld_ko_o)
125
126targets += $(modules)
127
128
129# Add FORCE to the prequisites of a target to force it to be always rebuilt.
130# ---------------------------------------------------------------------------
131
132PHONY += FORCE
133
134FORCE:
135
136# Read all saved command lines and dependencies for the $(targets) we
137# may be building above, using $(if_changed{,_dep}). As an
138# optimization, we don't need to read them if the target does not
139# exist, we will rebuild anyway in that case.
140
141targets := $(wildcard $(sort $(targets)))
142cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))
143
144ifneq ($(cmd_files),)
145  include $(cmd_files)
146endif
147
148
149# Declare the contents of the .PHONY variable as phony.  We keep that
150# information in a variable se we can use it in if_changed and friends.
151
152.PHONY: $(PHONY)
153