linux/scripts/Makefile.modpost
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   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)/
  63__modules := $(sort $(shell grep -h '\.ko$$' /dev/null $(wildcard $(MODVERDIR)/*.mod)))
  64modules   := $(patsubst %.o,%.ko, $(wildcard $(__modules:.ko=.o)))
  65
  66# Stop after building .o files if NOFINAL is set. Makes compile tests quicker
  67_modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules))
  68
  69# Step 2), invoke modpost
  70#  Includes step 3,4
  71modpost = scripts/mod/modpost                    \
  72 $(if $(CONFIG_MODVERSIONS),-m)                  \
  73 $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a,)       \
  74 $(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile)   \
  75 $(if $(KBUILD_EXTMOD),-I $(modulesymfile))      \
  76 $(if $(KBUILD_EXTRA_SYMBOLS), $(patsubst %, -e %,$(KBUILD_EXTRA_SYMBOLS))) \
  77 $(if $(KBUILD_EXTMOD),-o $(modulesymfile))      \
  78 $(if $(CONFIG_DEBUG_SECTION_MISMATCH),,-S)      \
  79 $(if $(KBUILD_EXTMOD)$(KBUILD_MODPOST_WARN),-w)
  80
  81quiet_cmd_modpost = MODPOST $(words $(filter-out vmlinux FORCE, $^)) modules
  82      cmd_modpost = $(modpost) -s
  83
  84PHONY += __modpost
  85__modpost: $(modules:.ko=.o) FORCE
  86        $(call cmd,modpost) $(wildcard vmlinux) $(filter-out FORCE,$^)
  87
  88quiet_cmd_kernel-mod = MODPOST $@
  89      cmd_kernel-mod = $(modpost) $@
  90
  91vmlinux.o: FORCE
  92        $(call cmd,kernel-mod)
  93
  94# Declare generated files as targets for modpost
  95$(symverfile):         __modpost ;
  96$(modules:.ko=.mod.c): __modpost ;
  97
  98
  99# Step 5), compile all *.mod.c files
 100
 101# modname is set to make c_flags define KBUILD_MODNAME
 102modname = $(notdir $(@:.mod.o=))
 103
 104quiet_cmd_cc_o_c = CC      $@
 105      cmd_cc_o_c = $(CC) $(c_flags) $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE) \
 106                   -c -o $@ $<
 107
 108$(modules:.ko=.mod.o): %.mod.o: %.mod.c FORCE
 109        $(call if_changed_dep,cc_o_c)
 110
 111targets += $(modules:.ko=.mod.o)
 112
 113# Step 6), final link of the modules
 114quiet_cmd_ld_ko_o = LD [M]  $@
 115      cmd_ld_ko_o = $(LD) -r $(LDFLAGS)                                 \
 116                             $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
 117                             -o $@ $(filter-out FORCE,$^)
 118
 119$(modules): %.ko :%.o %.mod.o FORCE
 120        $(call if_changed,ld_ko_o)
 121
 122targets += $(modules)
 123
 124
 125# Add FORCE to the prequisites of a target to force it to be always rebuilt.
 126# ---------------------------------------------------------------------------
 127
 128PHONY += FORCE
 129
 130FORCE:
 131
 132# Read all saved command lines and dependencies for the $(targets) we
 133# may be building above, using $(if_changed{,_dep}). As an
 134# optimization, we don't need to read them if the target does not
 135# exist, we will rebuild anyway in that case.
 136
 137targets := $(wildcard $(sort $(targets)))
 138cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))
 139
 140ifneq ($(cmd_files),)
 141  include $(cmd_files)
 142endif
 143
 144
 145# Declare the contents of the .PHONY variable as phony.  We keep that
 146# information in a variable se we can use it in if_changed and friends.
 147
 148.PHONY: $(PHONY)
 149
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