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-y :=
  19 always-m :=
  20 targets :=
  21 subdir-y :=
  22 subdir-m :=
  23 EXTRA_AFLAGS   :=
  24 EXTRA_CFLAGS   :=
  25 EXTRA_CPPFLAGS :=
  26 EXTRA_LDFLAGS  :=
  27 asflags-y  :=
  28 ccflags-y  :=
  29 cppflags-y :=
  30 ldflags-y  :=
  31
  32 subdir-asflags-y :=
  33 subdir-ccflags-y :=
  34
  35 # Read auto.conf if it exists, otherwise ignore
  36 -include include/config/auto.conf
  37
  38 include $(srctree)/scripts/Kbuild.include
  39 include $(srctree)/scripts/Makefile.compiler
  40
  41 # The filename Kbuild has precedence over Makefile
  42 kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
  43 include $(or $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Makefile)
  44
  45 include $(srctree)/scripts/Makefile.lib
  46
  47 # Do not include hostprogs rules unless needed.
  48 # $(sort ...) is used here to remove duplicated words and excessive spaces.
  49 hostprogs := $(sort $(hostprogs))
  50 ifneq ($(hostprogs),)
  51 include $(srctree)/scripts/Makefile.host
  52 endif
  53
  54 # Do not include userprogs rules unless needed.
  55 # $(sort ...) is used here to remove duplicated words and excessive spaces.
  56 userprogs := $(sort $(userprogs))
  57 ifneq ($(userprogs),)
  58 include $(srctree)/scripts/Makefile.userprogs
  59 endif
  60
  61 ifndef obj
  62 $(warning kbuild: Makefile.build is included improperly)
  63 endif
  64
  65 ifeq ($(need-modorder),)
  66 ifneq ($(obj-m),)
  67 $(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.)
  68 $(warning You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.)
  69 endif
  70 endif
  71
  72 # ===========================================================================
  73
  74 # subdir-builtin and subdir-modorder may contain duplications. Use $(sort ...)
  75 subdir-builtin := $(sort $(filter %/built-in.a, $(real-obj-y)))
  76 subdir-modorder := $(sort $(filter %/modules.order, $(obj-m)))
  77
  78 targets-for-builtin := $(extra-y)
  79
  80 ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
  81 targets-for-builtin += $(obj)/lib.a
  82 endif
  83
  84 ifdef need-builtin
  85 targets-for-builtin += $(obj)/built-in.a
  86 endif
  87
  88 targets-for-modules := $(foreach x, o mod $(if $(CONFIG_TRIM_UNUSED_KSYMS), usyms), \
  89                                 $(patsubst %.o, %.$x, $(filter %.o, $(obj-m))))
  90
  91 ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)
  92 targets-for-modules += $(patsubst %.o, %.prelink.o, $(filter %.o, $(obj-m)))
  93 endif
  94
  95 ifdef need-modorder
  96 targets-for-modules += $(obj)/modules.order
  97 endif
  98
  99 targets += $(targets-for-builtin) $(targets-for-modules)
 100
 101 # Linus' kernel sanity checking tool
 102 ifeq ($(KBUILD_CHECKSRC),1)
 103   quiet_cmd_checksrc       = CHECK   $<
 104         cmd_checksrc       = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
 105 else ifeq ($(KBUILD_CHECKSRC),2)
 106   quiet_cmd_force_checksrc = CHECK   $<
 107         cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
 108 endif
 109
 110 ifneq ($(KBUILD_EXTRA_WARN),)
 111   cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $<
 112 endif
 113
 114 # Compile C sources (.c)
 115 # ---------------------------------------------------------------------------
 116
 117 quiet_cmd_cc_s_c = CC $(quiet_modtag)  $@
 118       cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS) $(CC_FLAGS_LTO), $(c_flags)) -fverbose-asm -S -o $@ $<
 119
 120 $(obj)/%.s: $(src)/%.c FORCE
 121         $(call if_changed_dep,cc_s_c)
 122
 123 quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
 124 cmd_cpp_i_c       = $(CPP) $(c_flags) -o $@ $<
 125
 126 $(obj)/%.i: $(src)/%.c FORCE
 127         $(call if_changed_dep,cpp_i_c)
 128
 129 genksyms = scripts/genksyms/genksyms            \
 130         $(if $(1), -T $(2))                     \
 131         $(if $(KBUILD_PRESERVE), -p)            \
 132         -r $(or $(wildcard $(2:.symtypes=.symref)), /dev/null)
 133
 134 # These mirror gensymtypes_S and co below, keep them in synch.
 135 cmd_gensymtypes_c = $(CPP) -D__GENKSYMS__ $(c_flags) $< | $(genksyms)
 136
 137 quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
 138       cmd_cc_symtypes_c = $(call cmd_gensymtypes_c,true,$@) >/dev/null
 139
 140 $(obj)/%.symtypes : $(src)/%.c FORCE
 141         $(call cmd,cc_symtypes_c)
 142
 143 # LLVM assembly
 144 # Generate .ll files from .c
 145 quiet_cmd_cc_ll_c = CC $(quiet_modtag)  $@
 146       cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $<
 147
 148 $(obj)/%.ll: $(src)/%.c FORCE
 149         $(call if_changed_dep,cc_ll_c)
 150
 151 # C (.c) files
 152 # The C file is compiled and updated dependency information is generated.
 153 # (See cmd_cc_o_c + relevant part of rule_cc_o_c)
 154
 155 quiet_cmd_cc_o_c = CC $(quiet_modtag)  $@
 156       cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< $(cmd_objtool)
 157
 158 ifdef CONFIG_MODVERSIONS
 159 # When module versioning is enabled the following steps are executed:
 160 # o compile a <file>.o from <file>.c
 161 # o if <file>.o doesn't contain a __ksymtab version, i.e. does
 162 #   not export symbols, it's done.
 163 # o otherwise, we calculate symbol versions using the good old
 164 #   genksyms on the preprocessed source and dump them into the .cmd file.
 165 # o modpost will extract versions from that file and create *.c files that will
 166 #   be compiled and linked to the kernel and/or modules.
 167
 168 gen_symversions =                                                               \
 169         if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then                       \
 170                 $(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
 171                         >> $(dot-target).cmd;                                   \
 172         fi
 173
 174 cmd_gen_symversions_c = $(call gen_symversions,c)
 175
 176 endif
 177
 178 ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
 179 # compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
 180 ifdef BUILD_C_RECORDMCOUNT
 181 ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
 182   RECORDMCOUNT_FLAGS = -w
 183 endif
 184 # Due to recursion, we must skip empty.o.
 185 # The empty.o file is created in the make process in order to determine
 186 # the target endianness and word size. It is made before all other C
 187 # files, including recordmcount.
 188 sub_cmd_record_mcount =                                 \
 189         if [ $(@) != "scripts/mod/empty.o" ]; then      \
 190                 $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)";   \
 191         fi;
 192 recordmcount_source := $(srctree)/scripts/recordmcount.c \
 193                     $(srctree)/scripts/recordmcount.h
 194 else
 195 sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
 196         "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
 197         "$(if $(CONFIG_64BIT),64,32)" \
 198         "$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
 199         "$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
 200         "$(if $(part-of-module),1,0)" "$(@)";
 201 recordmcount_source := $(srctree)/scripts/recordmcount.pl
 202 endif # BUILD_C_RECORDMCOUNT
 203 cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), \
 204         $(sub_cmd_record_mcount))
 205 endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
 206
 207 ifdef CONFIG_OBJTOOL
 208
 209 objtool := $(objtree)/tools/objtool/objtool
 210
 211 objtool_args =                                                          \
 212         $(if $(CONFIG_HAVE_JUMP_LABEL_HACK), --hacks=jump_label)        \
 213         $(if $(CONFIG_HAVE_NOINSTR_HACK), --hacks=noinstr)              \
 214         $(if $(CONFIG_X86_KERNEL_IBT), --ibt)                           \
 215         $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount)             \
 216         $(if $(CONFIG_UNWINDER_ORC), --orc)                             \
 217         $(if $(CONFIG_RETPOLINE), --retpoline)                          \
 218         $(if $(CONFIG_SLS), --sls)                                      \
 219         $(if $(CONFIG_STACK_VALIDATION), --stackval)                    \
 220         $(if $(CONFIG_HAVE_STATIC_CALL_INLINE), --static-call)          \
 221         --uaccess                                                       \
 222         $(if $(linked-object), --link)                                  \
 223         $(if $(part-of-module), --module)                               \
 224         $(if $(CONFIG_GCOV_KERNEL), --no-unreachable)
 225
 226 cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
 227 cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
 228
 229 endif # CONFIG_OBJTOOL
 230
 231 ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)
 232
 233 # Skip objtool for LLVM bitcode
 234 $(obj)/%.o: objtool-enabled :=
 235
 236 else
 237
 238 # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
 239 # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
 240 # 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
 241
 242 $(obj)/%.o: objtool-enabled = $(if $(filter-out y%, \
 243         $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y)
 244
 245 endif
 246
 247 ifdef CONFIG_TRIM_UNUSED_KSYMS
 248 cmd_gen_ksymdeps = \
 249         $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd
 250 endif
 251
 252 define rule_cc_o_c
 253         $(call cmd_and_fixdep,cc_o_c)
 254         $(call cmd,gen_ksymdeps)
 255         $(call cmd,checksrc)
 256         $(call cmd,checkdoc)
 257         $(call cmd,gen_objtooldep)
 258         $(call cmd,gen_symversions_c)
 259         $(call cmd,record_mcount)
 260 endef
 261
 262 define rule_as_o_S
 263         $(call cmd_and_fixdep,as_o_S)
 264         $(call cmd,gen_ksymdeps)
 265         $(call cmd,gen_objtooldep)
 266         $(call cmd,gen_symversions_S)
 267 endef
 268
 269 # Built-in and composite module parts
 270 $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
 271         $(call if_changed_rule,cc_o_c)
 272         $(call cmd,force_checksrc)
 273
 274 ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)
 275 # Module .o files may contain LLVM bitcode, compile them into native code
 276 # before ELF processing
 277 quiet_cmd_cc_prelink_modules = LD [M]  $@
 278       cmd_cc_prelink_modules =                                          \
 279         $(LD) $(ld_flags) -r -o $@                                      \
 280                 --whole-archive $(filter-out FORCE,$^)                  \
 281                 $(cmd_objtool)
 282
 283 # objtool was skipped for LLVM bitcode, run it now that we have compiled
 284 # modules into native code
 285 $(obj)/%.prelink.o: objtool-enabled = y
 286 $(obj)/%.prelink.o: part-of-module := y
 287 $(obj)/%.prelink.o: linked-object := y
 288
 289 $(obj)/%.prelink.o: $(obj)/%.o FORCE
 290         $(call if_changed,cc_prelink_modules)
 291 endif
 292
 293 cmd_mod = echo $(addprefix $(obj)/, $(call real-search, $*.o, .o, -objs -y -m)) | \
 294         $(AWK) -v RS='( |\n)' '!x[$$0]++' > $@
 295
 296 $(obj)/%.mod: FORCE
 297         $(call if_changed,mod)
 298
 299 # List module undefined symbols
 300 cmd_undefined_syms = $(NM) $< | sed -n 's/^  *U //p' > $@
 301
 302 $(obj)/%.usyms: $(obj)/%$(mod-prelink-ext).o FORCE
 303         $(call if_changed,undefined_syms)
 304
 305 quiet_cmd_cc_lst_c = MKLST   $@
 306       cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
 307                      $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
 308                                      System.map $(OBJDUMP) > $@
 309
 310 $(obj)/%.lst: $(src)/%.c FORCE
 311         $(call if_changed_dep,cc_lst_c)
 312
 313 # Compile assembler sources (.S)
 314 # ---------------------------------------------------------------------------
 315
 316 # .S file exports must have their C prototypes defined in asm/asm-prototypes.h
 317 # or a file that it includes, in order to get versioned symbols. We build a
 318 # dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
 319 # the .S file (with trailing ';'), and run genksyms on that, to extract vers.
 320 #
 321 # This is convoluted. The .S file must first be preprocessed to run guards and
 322 # expand names, then the resulting exports must be constructed into plain
 323 # EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
 324 # to make the genksyms input.
 325 #
 326 # These mirror gensymtypes_c and co above, keep them in synch.
 327 cmd_gensymtypes_S =                                                         \
 328    { echo "\#include <linux/kernel.h>" ;                                    \
 329      echo "\#include <asm/asm-prototypes.h>" ;                              \
 330     $(CPP) $(a_flags) $< |                                                  \
 331      grep "\<___EXPORT_SYMBOL\>" |                                          \
 332      sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ; } | \
 333     $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | $(genksyms)
 334
 335 quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
 336       cmd_cc_symtypes_S = $(call cmd_gensymtypes_S,true,$@) >/dev/null
 337
 338 $(obj)/%.symtypes : $(src)/%.S FORCE
 339         $(call cmd,cc_symtypes_S)
 340
 341
 342 quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
 343 cmd_cpp_s_S       = $(CPP) $(a_flags) -o $@ $<
 344
 345 $(obj)/%.s: $(src)/%.S FORCE
 346         $(call if_changed_dep,cpp_s_S)
 347
 348 quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
 349       cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $< $(cmd_objtool)
 350
 351 ifdef CONFIG_ASM_MODVERSIONS
 352
 353 # versioning matches the C process described above, with difference that
 354 # we parse asm-prototypes.h C header to get function definitions.
 355
 356 cmd_gen_symversions_S = $(call gen_symversions,S)
 357
 358 endif
 359
 360 $(obj)/%.o: $(src)/%.S FORCE
 361         $(call if_changed_rule,as_o_S)
 362
 363 targets += $(filter-out $(subdir-builtin), $(real-obj-y))
 364 targets += $(filter-out $(subdir-modorder), $(real-obj-m))
 365 targets += $(real-dtb-y) $(lib-y) $(always-y) $(MAKECMDGOALS)
 366
 367 # Linker scripts preprocessor (.lds.S -> .lds)
 368 # ---------------------------------------------------------------------------
 369 quiet_cmd_cpp_lds_S = LDS     $@
 370       cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
 371                              -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
 372
 373 $(obj)/%.lds: $(src)/%.lds.S FORCE
 374         $(call if_changed_dep,cpp_lds_S)
 375
 376 # ASN.1 grammar
 377 # ---------------------------------------------------------------------------
 378 quiet_cmd_asn1_compiler = ASN.1   $(basename $@).[ch]
 379       cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
 380                                 $(basename $@).c $(basename $@).h
 381
 382 $(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
 383         $(call cmd,asn1_compiler)
 384
 385 # Build the compiled-in targets
 386 # ---------------------------------------------------------------------------
 387
 388 # To build objects in subdirs, we need to descend into the directories
 389 $(subdir-builtin): $(obj)/%/built-in.a: $(obj)/% ;
 390 $(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ;
 391
 392 #
 393 # Rule to compile a set of .o files into one .a file (without symbol table)
 394 #
 395
 396 quiet_cmd_ar_builtin = AR      $@
 397       cmd_ar_builtin = rm -f $@; $(AR) cDPrST $@ $(real-prereqs)
 398
 399 $(obj)/built-in.a: $(real-obj-y) FORCE
 400         $(call if_changed,ar_builtin)
 401
 402 #
 403 # Rule to create modules.order file
 404 #
 405 # Create commands to either record .ko file or cat modules.order from
 406 # a subdirectory
 407 # Add $(obj-m) as the prerequisite to avoid updating the timestamp of
 408 # modules.order unless contained modules are updated.
 409
 410 cmd_modules_order = { $(foreach m, $(real-prereqs), \
 411         $(if $(filter %/modules.order, $m), cat $m, echo $(patsubst %.o,%.ko,$m));) :; } \
 412         | $(AWK) '!x[$$0]++' - > $@
 413
 414 $(obj)/modules.order: $(obj-m) FORCE
 415         $(call if_changed,modules_order)
 416
 417 #
 418 # Rule to compile a set of .o files into one .a file (with symbol table)
 419 #
 420
 421 $(obj)/lib.a: $(lib-y) FORCE
 422         $(call if_changed,ar)
 423
 424 ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)
 425 quiet_cmd_link_multi-m = AR [M]  $@
 426 cmd_link_multi-m =                                              \
 427         rm -f $@;                                               \
 428         $(AR) cDPrsT $@ @$(patsubst %.o,%.mod,$@)
 429 else
 430 quiet_cmd_link_multi-m = LD [M]  $@
 431       cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ @$(patsubst %.o,%.mod,$@)
 432 endif
 433
 434 $(multi-obj-m): %.o: %.mod FORCE
 435         $(call if_changed,link_multi-m)
 436 $(call multi_depend, $(multi-obj-m), .o, -objs -y -m)
 437
 438 targets := $(filter-out $(PHONY), $(targets))
 439
 440 # Add intermediate targets:
 441 # When building objects with specific suffix patterns, add intermediate
 442 # targets that the final targets are derived from.
 443 intermediate_targets = $(foreach sfx, $(2), \
 444                                 $(patsubst %$(strip $(1)),%$(sfx), \
 445                                         $(filter %$(strip $(1)), $(targets))))
 446 # %.asn1.o <- %.asn1.[ch] <- %.asn1
 447 # %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
 448 # %.lex.o <- %.lex.c <- %.l
 449 # %.tab.o <- %.tab.[ch] <- %.y
 450 targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
 451            $(call intermediate_targets, .dtb.o, .dtb.S .dtb) \
 452            $(call intermediate_targets, .lex.o, .lex.c) \
 453            $(call intermediate_targets, .tab.o, .tab.c .tab.h)
 454
 455 # Build
 456 # ---------------------------------------------------------------------------
 457
 458 ifdef single-build
 459
 460 KBUILD_SINGLE_TARGETS := $(filter $(obj)/%, $(KBUILD_SINGLE_TARGETS))
 461
 462 curdir-single := $(sort $(foreach x, $(KBUILD_SINGLE_TARGETS), \
 463                         $(if $(filter $(x) $(basename $(x)).o, $(targets)), $(x))))
 464
 465 # Handle single targets without any rule: show "Nothing to be done for ..." or
 466 # "No rule to make target ..." depending on whether the target exists.
 467 unknown-single := $(filter-out $(addsuffix /%, $(subdir-ym)), \
 468                         $(filter-out $(curdir-single), $(KBUILD_SINGLE_TARGETS)))
 469
 470 single-subdirs := $(foreach d, $(subdir-ym), \
 471                         $(if $(filter $(d)/%, $(KBUILD_SINGLE_TARGETS)), $(d)))
 472
 473 __build: $(curdir-single) $(single-subdirs)
 474 ifneq ($(unknown-single),)
 475         $(Q)$(MAKE) -f /dev/null $(unknown-single)
 476 endif
 477         @:
 478
 479 ifeq ($(curdir-single),)
 480 # Nothing to do in this directory. Do not include any .*.cmd file for speed-up
 481 targets :=
 482 else
 483 targets += $(curdir-single)
 484 endif
 485
 486 else
 487
 488 __build: $(if $(KBUILD_BUILTIN), $(targets-for-builtin)) \
 489          $(if $(KBUILD_MODULES), $(targets-for-modules)) \
 490          $(subdir-ym) $(always-y)
 491         @:
 492
 493 endif
 494
 495 # Descending
 496 # ---------------------------------------------------------------------------
 497
 498 PHONY += $(subdir-ym)
 499 $(subdir-ym):
 500         $(Q)$(MAKE) $(build)=$@ \
 501         $(if $(filter $@/, $(KBUILD_SINGLE_TARGETS)),single-build=) \
 502         need-builtin=$(if $(filter $@/built-in.a, $(subdir-builtin)),1) \
 503         need-modorder=$(if $(filter $@/modules.order, $(subdir-modorder)),1)
 504
 505 # Add FORCE to the prequisites of a target to force it to be always rebuilt.
 506 # ---------------------------------------------------------------------------
 507
 508 PHONY += FORCE
 509
 510 FORCE:
 511
 512 # Read all saved command lines and dependencies for the $(targets) we
 513 # may be building above, using $(if_changed{,_dep}). As an
 514 # optimization, we don't need to read them if the target does not
 515 # exist, we will rebuild anyway in that case.
 516
 517 existing-targets := $(wildcard $(sort $(targets)))
 518
 519 -include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
 520
 521 # Create directories for object files if they do not exist
 522 obj-dirs := $(sort $(patsubst %/,%, $(dir $(targets))))
 523 # If targets exist, their directories apparently exist. Skip mkdir.
 524 existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))
 525 obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))
 526 ifneq ($(obj-dirs),)
 527 $(shell mkdir -p $(obj-dirs))
 528 endif
 529
 530 .PHONY: $(PHONY)