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