xref: /openbmc/linux/scripts/Makefile.modpost (revision 1da177e4) 
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 wich 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/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 retreived from the Module.symers file.
34
35.PHONY: _modpost
36_modpost: __modpost
37
38include .config
39include scripts/Makefile.lib
40
41symverfile := $(objtree)/Module.symvers
42
43# Step 1), find all modules listed in $(MODVERDIR)/
44__modules := $(sort $(shell grep -h '\.ko' /dev/null $(wildcard $(MODVERDIR)/*.mod)))
45modules   := $(patsubst %.o,%.ko, $(wildcard $(__modules:.ko=.o)))
46
47_modpost: $(modules)
48
49
50# Step 2), invoke modpost
51#  Includes step 3,4
52quiet_cmd_modpost = MODPOST
53      cmd_modpost = scripts/mod/modpost            \
54        $(if $(CONFIG_MODVERSIONS),-m)             \
55	$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a,)  \
56	$(if $(KBUILD_EXTMOD),-i,-o) $(symverfile) \
57	$(filter-out FORCE,$^)
58
59.PHONY: __modpost
60__modpost: $(wildcard vmlinux) $(modules:.ko=.o) FORCE
61	$(call cmd,modpost)
62
63# Declare generated files as targets for modpost
64$(symverfile):         __modpost ;
65$(modules:.ko=.mod.c): __modpost ;
66
67
68# Step 5), compile all *.mod.c files
69
70# modname is set to make c_flags define KBUILD_MODNAME
71modname = $(*F)
72
73quiet_cmd_cc_o_c = CC      $@
74      cmd_cc_o_c = $(CC) $(c_flags) $(CFLAGS_MODULE)	\
75		   -c -o $@ $<
76
77$(modules:.ko=.mod.o): %.mod.o: %.mod.c FORCE
78	$(call if_changed_dep,cc_o_c)
79
80targets += $(modules:.ko=.mod.o)
81
82# Step 6), final link of the modules
83quiet_cmd_ld_ko_o = LD [M]  $@
84      cmd_ld_ko_o = $(LD) $(LDFLAGS) $(LDFLAGS_MODULE) -o $@ 		\
85			  $(filter-out FORCE,$^)
86
87$(modules): %.ko :%.o %.mod.o FORCE
88	$(call if_changed,ld_ko_o)
89
90targets += $(modules)
91
92
93# Add FORCE to the prequisites of a target to force it to be always rebuilt.
94# ---------------------------------------------------------------------------
95
96.PHONY: FORCE
97
98FORCE:
99
100# Read all saved command lines and dependencies for the $(targets) we
101# may be building above, using $(if_changed{,_dep}). As an
102# optimization, we don't need to read them if the target does not
103# exist, we will rebuild anyway in that case.
104
105targets := $(wildcard $(sort $(targets)))
106cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))
107
108ifneq ($(cmd_files),)
109  include $(cmd_files)
110endif
111