scripts/Makefile.build

   1 # SPDX-License-Identifier: GPL-2.0
   2 # ==========================================================================
   3 # Building
   4 # ==========================================================================
   5
   6 src := $(obj)
   7
   8 PHONY := __build
   9 __build:
  10
  11 # Init all relevant variables used in kbuild files so
  12 # 1) they have correct type
  13 # 2) they do not inherit any value from the environment
  14 obj-y :=
  15 obj-m :=
  16 lib-y :=
  17 lib-m :=
  18 always :=
  19 always-y :=
  20 always-m :=
  21 targets :=
  22 subdir-y :=
  23 subdir-m :=
  24 EXTRA_AFLAGS   :=
  25 EXTRA_CFLAGS   :=
  26 EXTRA_CPPFLAGS :=
  27 EXTRA_LDFLAGS  :=
  28 asflags-y  :=
  29 ccflags-y  :=
  30 cppflags-y :=
  31 ldflags-y  :=
  32
  33 subdir-asflags-y :=
  34 subdir-ccflags-y :=
  35
  36 # Read auto.conf if it exists, otherwise ignore
  37 -include include/config/auto.conf
  38
  39 include scripts/Kbuild.include
  40
  41 # The filename Kbuild has precedence over Makefile
  42 kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
  43 kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
  44 include $(kbuild-file)
  45
  46 include scripts/Makefile.lib
  47
  48 # Do not include host rules unless needed
  49 ifneq ($(hostprogs)$(hostlibs-y)$(hostlibs-m)$(hostcxxlibs-y)$(hostcxxlibs-m),)
  50 include scripts/Makefile.host
  51 endif
  52
  53 ifndef obj
  54 $(warning kbuild: Makefile.build is included improperly)
  55 endif
  56
  57 ifeq ($(need-modorder),)
  58 ifneq ($(obj-m),)
  59 $(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.)
  60 $(warning You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.)
  61 endif
  62 endif
  63
  64 # ===========================================================================
  65
  66 ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
  67 lib-target := $(obj)/lib.a
  68 real-obj-y += $(obj)/lib-ksyms.o
  69 endif
  70
  71 ifdef need-builtin
  72 builtin-target := $(obj)/built-in.a
  73 endif
  74
  75 ifeq ($(CONFIG_MODULES)$(need-modorder),y1)
  76 modorder-target := $(obj)/modules.order
  77 endif
  78
  79 mod-targets := $(patsubst %.o, %.mod, $(obj-m))
  80
  81 # Linus' kernel sanity checking tool
  82 ifeq ($(KBUILD_CHECKSRC),1)
  83   quiet_cmd_checksrc       = CHECK   $<
  84         cmd_checksrc       = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
  85 else ifeq ($(KBUILD_CHECKSRC),2)
  86   quiet_cmd_force_checksrc = CHECK   $<
  87         cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
  88 endif
  89
  90 ifneq ($(KBUILD_EXTRA_WARN),)
  91   cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $<
  92 endif
  93
  94 # Compile C sources (.c)
  95 # ---------------------------------------------------------------------------
  96
  97 quiet_cmd_cc_s_c = CC $(quiet_modtag)  $@
  98       cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS), $(c_flags)) $(DISABLE_LTO) -fverbose-asm -S -o $@ $<
  99
 100 $(obj)/%.s: $(src)/%.c FORCE
 101         $(call if_changed_dep,cc_s_c)
 102
 103 quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
 104 cmd_cpp_i_c       = $(CPP) $(c_flags) -o $@ $<
 105
 106 $(obj)/%.i: $(src)/%.c FORCE
 107         $(call if_changed_dep,cpp_i_c)
 108
 109 # These mirror gensymtypes_S and co below, keep them in synch.
 110 cmd_gensymtypes_c =                                                         \
 111     $(CPP) -D__GENKSYMS__ $(c_flags) $< |                                   \
 112     scripts/genksyms/genksyms $(if $(1), -T $(2))                           \
 113      $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS))                             \
 114      $(if $(KBUILD_PRESERVE),-p)                                            \
 115      -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
 116
 117 quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
 118 cmd_cc_symtypes_c =                                                         \
 119     $(call cmd_gensymtypes_c,true,$@) >/dev/null;                           \
 120     test -s $@ || rm -f $@
 121
 122 $(obj)/%.symtypes : $(src)/%.c FORCE
 123         $(call cmd,cc_symtypes_c)
 124
 125 # LLVM assembly
 126 # Generate .ll files from .c
 127 quiet_cmd_cc_ll_c = CC $(quiet_modtag)  $@
 128       cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $<
 129
 130 $(obj)/%.ll: $(src)/%.c FORCE
 131         $(call if_changed_dep,cc_ll_c)
 132
 133 # C (.c) files
 134 # The C file is compiled and updated dependency information is generated.
 135 # (See cmd_cc_o_c + relevant part of rule_cc_o_c)
 136
 137 quiet_cmd_cc_o_c = CC $(quiet_modtag)  $@
 138       cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
 139
 140 ifdef CONFIG_MODVERSIONS
 141 # When module versioning is enabled the following steps are executed:
 142 # o compile a <file>.o from <file>.c
 143 # o if <file>.o doesn't contain a __ksymtab version, i.e. does
 144 #   not export symbols, it's done.
 145 # o otherwise, we calculate symbol versions using the good old
 146 #   genksyms on the preprocessed source and postprocess them in a way
 147 #   that they are usable as a linker script
 148 # o generate .tmp_<file>.o from <file>.o using the linker to
 149 #   replace the unresolved symbols __crc_exported_symbol with
 150 #   the actual value of the checksum generated by genksyms
 151 # o remove .tmp_<file>.o to <file>.o
 152
 153 cmd_modversions_c =                                                             \
 154         if $(OBJDUMP) -h $@ | grep -q __ksymtab; then                           \
 155                 $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))  \
 156                     > $(@D)/.tmp_$(@F:.o=.ver);                                 \
 157                                                                                 \
 158                 $(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@               \
 159                         -T $(@D)/.tmp_$(@F:.o=.ver);                            \
 160                 mv -f $(@D)/.tmp_$(@F) $@;                                      \
 161                 rm -f $(@D)/.tmp_$(@F:.o=.ver);                                 \
 162         fi
 163 endif
 164
 165 ifdef CONFIG_FTRACE_MCOUNT_RECORD
 166 ifndef CC_USING_RECORD_MCOUNT
 167 # compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
 168 ifdef BUILD_C_RECORDMCOUNT
 169 ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
 170   RECORDMCOUNT_FLAGS = -w
 171 endif
 172 # Due to recursion, we must skip empty.o.
 173 # The empty.o file is created in the make process in order to determine
 174 # the target endianness and word size. It is made before all other C
 175 # files, including recordmcount.
 176 sub_cmd_record_mcount =                                 \
 177         if [ $(@) != "scripts/mod/empty.o" ]; then      \
 178                 $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)";   \
 179         fi;
 180 recordmcount_source := $(srctree)/scripts/recordmcount.c \
 181                     $(srctree)/scripts/recordmcount.h
 182 else
 183 sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
 184         "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
 185         "$(if $(CONFIG_64BIT),64,32)" \
 186         "$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
 187         "$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
 188         "$(if $(part-of-module),1,0)" "$(@)";
 189 recordmcount_source := $(srctree)/scripts/recordmcount.pl
 190 endif # BUILD_C_RECORDMCOUNT
 191 cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), \
 192         $(sub_cmd_record_mcount))
 193 endif # CC_USING_RECORD_MCOUNT
 194 endif # CONFIG_FTRACE_MCOUNT_RECORD
 195
 196 ifdef CONFIG_STACK_VALIDATION
 197 ifneq ($(SKIP_STACK_VALIDATION),1)
 198
 199 __objtool_obj := $(objtree)/tools/objtool/objtool
 200
 201 objtool_args = $(if $(CONFIG_UNWINDER_ORC),orc generate,check)
 202
 203 objtool_args += $(if $(part-of-module), --module,)
 204
 205 ifndef CONFIG_FRAME_POINTER
 206 objtool_args += --no-fp
 207 endif
 208 ifdef CONFIG_GCOV_KERNEL
 209 objtool_args += --no-unreachable
 210 endif
 211 ifdef CONFIG_RETPOLINE
 212   objtool_args += --retpoline
 213 endif
 214 ifdef CONFIG_X86_SMAP
 215   objtool_args += --uaccess
 216 endif
 217
 218 # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
 219 # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
 220 # 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
 221 cmd_objtool = $(if $(patsubst y%,, \
 222         $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
 223         $(__objtool_obj) $(objtool_args) $@)
 224 objtool_obj = $(if $(patsubst y%,, \
 225         $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
 226         $(__objtool_obj))
 227
 228 endif # SKIP_STACK_VALIDATION
 229 endif # CONFIG_STACK_VALIDATION
 230
 231 # Rebuild all objects when objtool changes, or is enabled/disabled.
 232 objtool_dep = $(objtool_obj)                                    \
 233               $(wildcard include/config/orc/unwinder.h          \
 234                          include/config/stack/validation.h)
 235
 236 ifdef CONFIG_TRIM_UNUSED_KSYMS
 237 cmd_gen_ksymdeps = \
 238         $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd
 239 endif
 240
 241 define rule_cc_o_c
 242         $(call cmd,checksrc)
 243         $(call cmd_and_fixdep,cc_o_c)
 244         $(call cmd,gen_ksymdeps)
 245         $(call cmd,checkdoc)
 246         $(call cmd,objtool)
 247         $(call cmd,modversions_c)
 248         $(call cmd,record_mcount)
 249 endef
 250
 251 define rule_as_o_S
 252         $(call cmd_and_fixdep,as_o_S)
 253         $(call cmd,gen_ksymdeps)
 254         $(call cmd,objtool)
 255         $(call cmd,modversions_S)
 256 endef
 257
 258 # List module undefined symbols (or empty line if not enabled)
 259 ifdef CONFIG_TRIM_UNUSED_KSYMS
 260 cmd_undef_syms = $(NM) $< | sed -n 's/^  *U //p' | xargs echo
 261 else
 262 cmd_undef_syms = echo
 263 endif
 264
 265 # Built-in and composite module parts
 266 $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
 267         $(call cmd,force_checksrc)
 268         $(call if_changed_rule,cc_o_c)
 269
 270 cmd_mod = { \
 271         echo $(if $($*-objs)$($*-y)$($*-m), $(addprefix $(obj)/, $($*-objs) $($*-y) $($*-m)), $(@:.mod=.o)); \
 272         $(cmd_undef_syms); \
 273         } > $@
 274
 275 $(obj)/%.mod: $(obj)/%.o FORCE
 276         $(call if_changed,mod)
 277
 278 targets += $(mod-targets)
 279
 280 quiet_cmd_cc_lst_c = MKLST   $@
 281       cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
 282                      $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
 283                                      System.map $(OBJDUMP) > $@
 284
 285 $(obj)/%.lst: $(src)/%.c FORCE
 286         $(call if_changed_dep,cc_lst_c)
 287
 288 # Compile assembler sources (.S)
 289 # ---------------------------------------------------------------------------
 290
 291 # .S file exports must have their C prototypes defined in asm/asm-prototypes.h
 292 # or a file that it includes, in order to get versioned symbols. We build a
 293 # dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
 294 # the .S file (with trailing ';'), and run genksyms on that, to extract vers.
 295 #
 296 # This is convoluted. The .S file must first be preprocessed to run guards and
 297 # expand names, then the resulting exports must be constructed into plain
 298 # EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
 299 # to make the genksyms input.
 300 #
 301 # These mirror gensymtypes_c and co above, keep them in synch.
 302 cmd_gensymtypes_S =                                                         \
 303    { echo "\#include <linux/kernel.h>" ;                                    \
 304      echo "\#include <asm/asm-prototypes.h>" ;                              \
 305     $(CPP) $(a_flags) $< |                                                  \
 306      grep "\<___EXPORT_SYMBOL\>" |                                          \
 307      sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ; } | \
 308     $(CPP) -D__GENKSYMS__ $(c_flags) -xc - |                                \
 309     scripts/genksyms/genksyms $(if $(1), -T $(2))                           \
 310      $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS))                             \
 311      $(if $(KBUILD_PRESERVE),-p)                                            \
 312      -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
 313
 314 quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
 315 cmd_cc_symtypes_S =                                                         \
 316     $(call cmd_gensymtypes_S,true,$@) >/dev/null;                           \
 317     test -s $@ || rm -f $@
 318
 319 $(obj)/%.symtypes : $(src)/%.S FORCE
 320         $(call cmd,cc_symtypes_S)
 321
 322
 323 quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
 324 cmd_cpp_s_S       = $(CPP) $(a_flags) -o $@ $<
 325
 326 $(obj)/%.s: $(src)/%.S FORCE
 327         $(call if_changed_dep,cpp_s_S)
 328
 329 quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
 330       cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
 331
 332 ifdef CONFIG_ASM_MODVERSIONS
 333
 334 # versioning matches the C process described above, with difference that
 335 # we parse asm-prototypes.h C header to get function definitions.
 336
 337 cmd_modversions_S =                                                             \
 338         if $(OBJDUMP) -h $@ | grep -q __ksymtab; then                           \
 339                 $(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))  \
 340                     > $(@D)/.tmp_$(@F:.o=.ver);                                 \
 341                                                                                 \
 342                 $(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@               \
 343                         -T $(@D)/.tmp_$(@F:.o=.ver);                            \
 344                 mv -f $(@D)/.tmp_$(@F) $@;                                      \
 345                 rm -f $(@D)/.tmp_$(@F:.o=.ver);                                 \
 346         fi
 347 endif
 348
 349 $(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE
 350         $(call if_changed_rule,as_o_S)
 351
 352 targets += $(filter-out $(subdir-obj-y), $(real-obj-y)) $(real-obj-m) $(lib-y)
 353 targets += $(extra-y) $(always-y) $(MAKECMDGOALS)
 354
 355 # Linker scripts preprocessor (.lds.S -> .lds)
 356 # ---------------------------------------------------------------------------
 357 quiet_cmd_cpp_lds_S = LDS     $@
 358       cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
 359                              -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
 360
 361 $(obj)/%.lds: $(src)/%.lds.S FORCE
 362         $(call if_changed_dep,cpp_lds_S)
 363
 364 # ASN.1 grammar
 365 # ---------------------------------------------------------------------------
 366 quiet_cmd_asn1_compiler = ASN.1   $(basename $@).[ch]
 367       cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
 368                                 $(basename $@).c $(basename $@).h
 369
 370 $(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
 371         $(call cmd,asn1_compiler)
 372
 373 # Build the compiled-in targets
 374 # ---------------------------------------------------------------------------
 375
 376 # To build objects in subdirs, we need to descend into the directories
 377 $(obj)/%/built-in.a: $(obj)/% ;
 378
 379 #
 380 # Rule to compile a set of .o files into one .a file (without symbol table)
 381 #
 382 ifdef builtin-target
 383
 384 quiet_cmd_ar_builtin = AR      $@
 385       cmd_ar_builtin = rm -f $@; $(AR) cDPrST $@ $(real-prereqs)
 386
 387 $(builtin-target): $(real-obj-y) FORCE
 388         $(call if_changed,ar_builtin)
 389
 390 targets += $(builtin-target)
 391 endif # builtin-target
 392
 393 #
 394 # Rule to create modules.order file
 395 #
 396 # Create commands to either record .ko file or cat modules.order from
 397 # a subdirectory
 398 $(modorder-target): $(subdir-ym) FORCE
 399         $(Q){ $(foreach m, $(modorder), \
 400         $(if $(filter %/modules.order, $m), cat $m, echo $m);) :; } \
 401         | $(AWK) '!x[$$0]++' - > $@
 402
 403 #
 404 # Rule to compile a set of .o files into one .a file (with symbol table)
 405 #
 406 ifdef lib-target
 407
 408 $(lib-target): $(lib-y) FORCE
 409         $(call if_changed,ar)
 410
 411 targets += $(lib-target)
 412
 413 dummy-object = $(obj)/.lib_exports.o
 414 ksyms-lds = $(dot-target).lds
 415
 416 quiet_cmd_export_list = EXPORTS $@
 417 cmd_export_list = $(OBJDUMP) -h $< | \
 418         sed -ne '/___ksymtab/s/.*+\([^ ]*\).*/EXTERN(\1)/p' >$(ksyms-lds);\
 419         rm -f $(dummy-object);\
 420         echo | $(CC) $(a_flags) -c -o $(dummy-object) -x assembler -;\
 421         $(LD) $(ld_flags) -r -o $@ -T $(ksyms-lds) $(dummy-object);\
 422         rm $(dummy-object) $(ksyms-lds)
 423
 424 $(obj)/lib-ksyms.o: $(lib-target) FORCE
 425         $(call if_changed,export_list)
 426
 427 targets += $(obj)/lib-ksyms.o
 428
 429 endif
 430
 431 # NOTE:
 432 # Do not replace $(filter %.o,^) with $(real-prereqs). When a single object
 433 # module is turned into a multi object module, $^ will contain header file
 434 # dependencies recorded in the .*.cmd file.
 435 quiet_cmd_link_multi-m = LD [M]  $@
 436       cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(filter %.o,$^)
 437
 438 $(multi-used-m): FORCE
 439         $(call if_changed,link_multi-m)
 440 $(call multi_depend, $(multi-used-m), .o, -objs -y -m)
 441
 442 targets += $(multi-used-m)
 443 targets := $(filter-out $(PHONY), $(targets))
 444
 445 # Add intermediate targets:
 446 # When building objects with specific suffix patterns, add intermediate
 447 # targets that the final targets are derived from.
 448 intermediate_targets = $(foreach sfx, $(2), \
 449                                 $(patsubst %$(strip $(1)),%$(sfx), \
 450                                         $(filter %$(strip $(1)), $(targets))))
 451 # %.asn1.o <- %.asn1.[ch] <- %.asn1
 452 # %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
 453 # %.lex.o <- %.lex.c <- %.l
 454 # %.tab.o <- %.tab.[ch] <- %.y
 455 targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
 456            $(call intermediate_targets, .dtb.o, .dtb.S .dtb) \
 457            $(call intermediate_targets, .lex.o, .lex.c) \
 458            $(call intermediate_targets, .tab.o, .tab.c .tab.h)
 459
 460 # Build
 461 # ---------------------------------------------------------------------------
 462
 463 ifdef single-build
 464
 465 KBUILD_SINGLE_TARGETS := $(filter $(obj)/%, $(KBUILD_SINGLE_TARGETS))
 466
 467 curdir-single := $(sort $(foreach x, $(KBUILD_SINGLE_TARGETS), \
 468                         $(if $(filter $(x) $(basename $(x)).o, $(targets)), $(x))))
 469
 470 # Handle single targets without any rule: show "Nothing to be done for ..." or
 471 # "No rule to make target ..." depending on whether the target exists.
 472 unknown-single := $(filter-out $(addsuffix /%, $(subdir-ym)), \
 473                         $(filter-out $(curdir-single), $(KBUILD_SINGLE_TARGETS)))
 474
 475 single-subdirs := $(foreach d, $(subdir-ym), \
 476                         $(if $(filter $(d)/%, $(KBUILD_SINGLE_TARGETS)), $(d)))
 477
 478 __build: $(curdir-single) $(single-subdirs)
 479 ifneq ($(unknown-single),)
 480         $(Q)$(MAKE) -f /dev/null $(unknown-single)
 481 endif
 482         @:
 483
 484 ifeq ($(curdir-single),)
 485 # Nothing to do in this directory. Do not include any .*.cmd file for speed-up
 486 targets :=
 487 else
 488 targets += $(curdir-single)
 489 endif
 490
 491 else
 492
 493 __build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
 494          $(if $(KBUILD_MODULES),$(obj-m) $(mod-targets) $(modorder-target)) \
 495          $(subdir-ym) $(always-y)
 496         @:
 497
 498 endif
 499
 500 # Descending
 501 # ---------------------------------------------------------------------------
 502
 503 PHONY += $(subdir-ym)
 504 $(subdir-ym):
 505         $(Q)$(MAKE) $(build)=$@ \
 506         $(if $(filter $@/, $(KBUILD_SINGLE_TARGETS)),single-build=) \
 507         need-builtin=$(if $(filter $@/built-in.a, $(subdir-obj-y)),1) \
 508         need-modorder=$(if $(need-modorder),$(if $(filter $@/modules.order, $(modorder)),1))
 509
 510 # Add FORCE to the prequisites of a target to force it to be always rebuilt.
 511 # ---------------------------------------------------------------------------
 512
 513 PHONY += FORCE
 514
 515 FORCE:
 516
 517 # Read all saved command lines and dependencies for the $(targets) we
 518 # may be building above, using $(if_changed{,_dep}). As an
 519 # optimization, we don't need to read them if the target does not
 520 # exist, we will rebuild anyway in that case.
 521
 522 existing-targets := $(wildcard $(sort $(targets)))
 523
 524 -include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
 525
 526 ifdef building_out_of_srctree
 527 # Create directories for object files if they do not exist
 528 obj-dirs := $(sort $(obj) $(patsubst %/,%, $(dir $(targets))))
 529 # If targets exist, their directories apparently exist. Skip mkdir.
 530 existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))
 531 obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))
 532 ifneq ($(obj-dirs),)
 533 $(shell mkdir -p $(obj-dirs))
 534 endif
 535 endif
 536
 537 .PHONY: $(PHONY)