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