scripts/Makefile.build

   1 # ==========================================================================
   2 # Building
   3 # ==========================================================================
   4
   5 src := $(obj)
   6
   7 PHONY := __build
   8 __build:
   9
  10 # Init all relevant variables used in kbuild files so
  11 # 1) they have correct type
  12 # 2) they do not inherit any value from the environment
  13 obj-y :=
  14 obj-m :=
  15 lib-y :=
  16 lib-m :=
  17 always :=
  18 targets :=
  19 subdir-y :=
  20 subdir-m :=
  21 EXTRA_AFLAGS   :=
  22 EXTRA_CFLAGS   :=
  23 EXTRA_CPPFLAGS :=
  24 EXTRA_LDFLAGS  :=
  25 asflags-y  :=
  26 ccflags-y  :=
  27 cppflags-y :=
  28 ldflags-y  :=
  29
  30 subdir-asflags-y :=
  31 subdir-ccflags-y :=
  32
  33 # Read auto.conf if it exists, otherwise ignore
  34 -include include/config/auto.conf
  35
  36 include scripts/Kbuild.include
  37
  38 # For backward compatibility check that these variables do not change
  39 save-cflags := $(CFLAGS)
  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 $(kbuild-file)
  45
  46 # If the save-* variables changed error out
  47 ifeq ($(KBUILD_NOPEDANTIC),)
  48         ifneq ("$(save-cflags)","$(CFLAGS)")
  49                 $(error CFLAGS was changed in "$(kbuild-file)". Fix it to use ccflags-y)
  50         endif
  51 endif
  52
  53 include scripts/Makefile.lib
  54
  55 ifdef host-progs
  56 ifneq ($(hostprogs-y),$(host-progs))
  57 $(warning kbuild: $(obj)/Makefile - Usage of host-progs is deprecated. Please replace with hostprogs-y!)
  58 hostprogs-y += $(host-progs)
  59 endif
  60 endif
  61
  62 # Do not include host rules unless needed
  63 ifneq ($(hostprogs-y)$(hostprogs-m),)
  64 include scripts/Makefile.host
  65 endif
  66
  67 ifneq ($(KBUILD_SRC),)
  68 # Create output directory if not already present
  69 _dummy := $(shell [ -d $(obj) ] || mkdir -p $(obj))
  70
  71 # Create directories for object files if directory does not exist
  72 # Needed when obj-y := dir/file.o syntax is used
  73 _dummy := $(foreach d,$(obj-dirs), $(shell [ -d $(d) ] || mkdir -p $(d)))
  74 endif
  75
  76 ifndef obj
  77 $(warning kbuild: Makefile.build is included improperly)
  78 endif
  79
  80 # ===========================================================================
  81
  82 ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
  83 lib-target := $(obj)/lib.a
  84 endif
  85
  86 ifneq ($(strip $(obj-y) $(obj-m) $(obj-) $(subdir-m) $(lib-target)),)
  87 builtin-target := $(obj)/built-in.o
  88 endif
  89
  90 modorder-target := $(obj)/modules.order
  91
  92 # We keep a list of all modules in $(MODVERDIR)
  93
  94 __build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
  95          $(if $(KBUILD_MODULES),$(obj-m) $(modorder-target)) \
  96          $(subdir-ym) $(always)
  97         @:
  98
  99 # Linus' kernel sanity checking tool
 100 ifneq ($(KBUILD_CHECKSRC),0)
 101   ifeq ($(KBUILD_CHECKSRC),2)
 102     quiet_cmd_force_checksrc = CHECK   $<
 103           cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
 104   else
 105       quiet_cmd_checksrc     = CHECK   $<
 106             cmd_checksrc     = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
 107   endif
 108 endif
 109
 110 # Do section mismatch analysis for each module/built-in.o
 111 ifdef CONFIG_DEBUG_SECTION_MISMATCH
 112   cmd_secanalysis = ; scripts/mod/modpost $@
 113 endif
 114
 115 # Compile C sources (.c)
 116 # ---------------------------------------------------------------------------
 117
 118 # Default is built-in, unless we know otherwise
 119 modkern_cflags =                                          \
 120         $(if $(part-of-module),                           \
 121                 $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE), \
 122                 $(KBUILD_CFLAGS_KERNEL) $(CFLAGS_KERNEL))
 123 quiet_modtag := $(empty)   $(empty)
 124
 125 $(real-objs-m)        : part-of-module := y
 126 $(real-objs-m:.o=.i)  : part-of-module := y
 127 $(real-objs-m:.o=.s)  : part-of-module := y
 128 $(real-objs-m:.o=.lst): part-of-module := y
 129
 130 $(real-objs-m)        : quiet_modtag := [M]
 131 $(real-objs-m:.o=.i)  : quiet_modtag := [M]
 132 $(real-objs-m:.o=.s)  : quiet_modtag := [M]
 133 $(real-objs-m:.o=.lst): quiet_modtag := [M]
 134
 135 $(obj-m)              : quiet_modtag := [M]
 136
 137 # Default for not multi-part modules
 138 modname = $(basetarget)
 139
 140 $(multi-objs-m)         : modname = $(modname-multi)
 141 $(multi-objs-m:.o=.i)   : modname = $(modname-multi)
 142 $(multi-objs-m:.o=.s)   : modname = $(modname-multi)
 143 $(multi-objs-m:.o=.lst) : modname = $(modname-multi)
 144 $(multi-objs-y)         : modname = $(modname-multi)
 145 $(multi-objs-y:.o=.i)   : modname = $(modname-multi)
 146 $(multi-objs-y:.o=.s)   : modname = $(modname-multi)
 147 $(multi-objs-y:.o=.lst) : modname = $(modname-multi)
 148
 149 quiet_cmd_cc_s_c = CC $(quiet_modtag)  $@
 150 cmd_cc_s_c       = $(CC) $(c_flags) $(DISABLE_LTO) -fverbose-asm -S -o $@ $<
 151
 152 $(obj)/%.s: $(src)/%.c FORCE
 153         $(call if_changed_dep,cc_s_c)
 154
 155 quiet_cmd_cc_i_c = CPP $(quiet_modtag) $@
 156 cmd_cc_i_c       = $(CPP) $(c_flags)   -o $@ $<
 157
 158 $(obj)/%.i: $(src)/%.c FORCE
 159         $(call if_changed_dep,cc_i_c)
 160
 161 # These mirror gensymtypes_S and co below, keep them in synch.
 162 cmd_gensymtypes_c =                                                         \
 163     $(CPP) -D__GENKSYMS__ $(c_flags) $< |                                   \
 164     $(GENKSYMS) $(if $(1), -T $(2))                                         \
 165      $(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX))             \
 166      $(if $(KBUILD_PRESERVE),-p)                                            \
 167      -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
 168
 169 quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
 170 cmd_cc_symtypes_c =                                                         \
 171     set -e;                                                                 \
 172     $(call cmd_gensymtypes_c,true,$@) >/dev/null;                           \
 173     test -s $@ || rm -f $@
 174
 175 $(obj)/%.symtypes : $(src)/%.c FORCE
 176         $(call cmd,cc_symtypes_c)
 177
 178 # LLVM assembly
 179 # Generate .ll files from .c
 180 quiet_cmd_cc_ll_c = CC $(quiet_modtag)  $@
 181       cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $<
 182
 183 $(obj)/%.ll: $(src)/%.c FORCE
 184         $(call if_changed_dep,cc_ll_c)
 185
 186 # C (.c) files
 187 # The C file is compiled and updated dependency information is generated.
 188 # (See cmd_cc_o_c + relevant part of rule_cc_o_c)
 189
 190 quiet_cmd_cc_o_c = CC $(quiet_modtag)  $@
 191
 192 ifndef CONFIG_MODVERSIONS
 193 cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
 194
 195 else
 196 # When module versioning is enabled the following steps are executed:
 197 # o compile a .tmp_<file>.o from <file>.c
 198 # o if .tmp_<file>.o doesn't contain a __ksymtab version, i.e. does
 199 #   not export symbols, we just rename .tmp_<file>.o to <file>.o and
 200 #   are done.
 201 # o otherwise, we calculate symbol versions using the good old
 202 #   genksyms on the preprocessed source and postprocess them in a way
 203 #   that they are usable as a linker script
 204 # o generate <file>.o from .tmp_<file>.o using the linker to
 205 #   replace the unresolved symbols __crc_exported_symbol with
 206 #   the actual value of the checksum generated by genksyms
 207
 208 cmd_cc_o_c = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $<
 209
 210 cmd_modversions_c =                                                             \
 211         if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then             \
 212                 $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))  \
 213                     > $(@D)/.tmp_$(@F:.o=.ver);                                 \
 214                                                                                 \
 215                 $(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F)                      \
 216                         -T $(@D)/.tmp_$(@F:.o=.ver);                            \
 217                 rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver);                \
 218         else                                                                    \
 219                 mv -f $(@D)/.tmp_$(@F) $@;                                      \
 220         fi;
 221 endif
 222
 223 ifdef CONFIG_FTRACE_MCOUNT_RECORD
 224 ifdef BUILD_C_RECORDMCOUNT
 225 ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
 226   RECORDMCOUNT_FLAGS = -w
 227 endif
 228 # Due to recursion, we must skip empty.o.
 229 # The empty.o file is created in the make process in order to determine
 230 #  the target endianness and word size. It is made before all other C
 231 #  files, including recordmcount.
 232 sub_cmd_record_mcount =                                 \
 233         if [ $(@) != "scripts/mod/empty.o" ]; then      \
 234                 $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)";   \
 235         fi;
 236 recordmcount_source := $(srctree)/scripts/recordmcount.c \
 237                     $(srctree)/scripts/recordmcount.h
 238 else
 239 sub_cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
 240         "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
 241         "$(if $(CONFIG_64BIT),64,32)" \
 242         "$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CFLAGS)" \
 243         "$(LD)" "$(NM)" "$(RM)" "$(MV)" \
 244         "$(if $(part-of-module),1,0)" "$(@)";
 245 recordmcount_source := $(srctree)/scripts/recordmcount.pl
 246 endif
 247 cmd_record_mcount =                                             \
 248         if [ "$(findstring $(CC_FLAGS_FTRACE),$(_c_flags))" =   \
 249              "$(CC_FLAGS_FTRACE)" ]; then                       \
 250                 $(sub_cmd_record_mcount)                        \
 251         fi;
 252 endif
 253
 254 define rule_cc_o_c
 255         $(call echo-cmd,checksrc) $(cmd_checksrc)                         \
 256         $(call echo-cmd,cc_o_c) $(cmd_cc_o_c);                            \
 257         $(cmd_modversions_c)                                              \
 258         $(call echo-cmd,record_mcount)                                    \
 259         $(cmd_record_mcount)                                              \
 260         scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' >    \
 261                                                       $(dot-target).tmp;  \
 262         rm -f $(depfile);                                                 \
 263         mv -f $(dot-target).tmp $(dot-target).cmd
 264 endef
 265
 266 define rule_as_o_S
 267        $(call echo-cmd,as_o_S) $(cmd_as_o_S);                            \
 268        scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,as_o_S)' >    \
 269                                                      $(dot-target).tmp;  \
 270        $(cmd_modversions_S)                                              \
 271        rm -f $(depfile);                                                 \
 272        mv -f $(dot-target).tmp $(dot-target).cmd
 273 endef
 274
 275 # Built-in and composite module parts
 276 $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
 277         $(call cmd,force_checksrc)
 278         $(call if_changed_rule,cc_o_c)
 279
 280 # Single-part modules are special since we need to mark them in $(MODVERDIR)
 281
 282 $(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
 283         $(call cmd,force_checksrc)
 284         $(call if_changed_rule,cc_o_c)
 285         @{ echo $(@:.o=.ko); echo $@; } > $(MODVERDIR)/$(@F:.o=.mod)
 286
 287 quiet_cmd_cc_lst_c = MKLST   $@
 288       cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
 289                      $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
 290                                      System.map $(OBJDUMP) > $@
 291
 292 $(obj)/%.lst: $(src)/%.c FORCE
 293         $(call if_changed_dep,cc_lst_c)
 294
 295 # Compile assembler sources (.S)
 296 # ---------------------------------------------------------------------------
 297
 298 modkern_aflags := $(KBUILD_AFLAGS_KERNEL) $(AFLAGS_KERNEL)
 299
 300 $(real-objs-m)      : modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
 301 $(real-objs-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
 302
 303 # .S file exports must have their C prototypes defined in asm/asm-prototypes.h
 304 # or a file that it includes, in order to get versioned symbols. We build a
 305 # dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
 306 # the .S file (with trailing ';'), and run genksyms on that, to extract vers.
 307 #
 308 # This is convoluted. The .S file must first be preprocessed to run guards and
 309 # expand names, then the resulting exports must be constructed into plain
 310 # EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
 311 # to make the genksyms input.
 312 #
 313 # These mirror gensymtypes_c and co above, keep them in synch.
 314 cmd_gensymtypes_S =                                                         \
 315     (echo "\#include <linux/kernel.h>" ;                                    \
 316      echo "\#include <asm/asm-prototypes.h>" ;                              \
 317     $(CPP) $(a_flags) $< |                                                  \
 318       grep "\<___EXPORT_SYMBOL\>" |                                          \
 319       sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ) | \
 320     $(CPP) -D__GENKSYMS__ $(c_flags) -xc - |                                \
 321     $(GENKSYMS) $(if $(1), -T $(2))                                         \
 322      $(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX))             \
 323      $(if $(KBUILD_PRESERVE),-p)                                            \
 324      -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
 325
 326 quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
 327 cmd_cc_symtypes_S =                                                         \
 328     set -e;                                                                 \
 329     $(call cmd_gensymtypes_S,true,$@) >/dev/null;                           \
 330     test -s $@ || rm -f $@
 331
 332 $(obj)/%.symtypes : $(src)/%.S FORCE
 333         $(call cmd,cc_symtypes_S)
 334
 335 quiet_cmd_as_s_S = CPP $(quiet_modtag) $@
 336 cmd_as_s_S       = $(CPP) $(a_flags)   -o $@ $<
 337
 338 $(obj)/%.s: $(src)/%.S FORCE
 339         $(call if_changed_dep,as_s_S)
 340
 341 quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
 342
 343 ifndef CONFIG_MODVERSIONS
 344 cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
 345
 346 else
 347
 348 ASM_PROTOTYPES := $(wildcard $(srctree)/arch/$(SRCARCH)/include/asm/asm-prototypes.h)
 349
 350 ifeq ($(ASM_PROTOTYPES),)
 351 cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
 352
 353 else
 354
 355 # versioning matches the C process described above, with difference that
 356 # we parse asm-prototypes.h C header to get function definitions.
 357
 358 cmd_as_o_S = $(CC) $(a_flags) -c -o $(@D)/.tmp_$(@F) $<
 359
 360 cmd_modversions_S =                                                             \
 361         if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then             \
 362                 $(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))  \
 363                     > $(@D)/.tmp_$(@F:.o=.ver);                                 \
 364                                                                                 \
 365                 $(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F)                      \
 366                         -T $(@D)/.tmp_$(@F:.o=.ver);                            \
 367                 rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver);                \
 368         else                                                                    \
 369                 mv -f $(@D)/.tmp_$(@F) $@;                                      \
 370         fi;
 371 endif
 372 endif
 373
 374 $(obj)/%.o: $(src)/%.S FORCE
 375         $(call if_changed_rule,as_o_S)
 376
 377 targets += $(real-objs-y) $(real-objs-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) $(cpp_flags) -P -C -U$(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 .PRECIOUS: $(objtree)/$(obj)/%-asn1.c $(objtree)/$(obj)/%-asn1.h
 396
 397 $(obj)/%-asn1.c $(obj)/%-asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
 398         $(call cmd,asn1_compiler)
 399
 400 # Build the compiled-in targets
 401 # ---------------------------------------------------------------------------
 402
 403 # To build objects in subdirs, we need to descend into the directories
 404 $(sort $(subdir-obj-y)): $(subdir-ym) ;
 405
 406 #
 407 # Rule to compile a set of .o files into one .o file
 408 #
 409 ifdef builtin-target
 410 quiet_cmd_link_o_target = LD      $@
 411 # If the list of objects to link is empty, just create an empty built-in.o
 412 cmd_link_o_target = $(if $(strip $(obj-y)),\
 413                       $(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^) \
 414                       $(cmd_secanalysis),\
 415                       rm -f $@; $(AR) rcs$(KBUILD_ARFLAGS) $@)
 416
 417 $(builtin-target): $(obj-y) FORCE
 418         $(call if_changed,link_o_target)
 419
 420 targets += $(builtin-target)
 421 endif # builtin-target
 422
 423 #
 424 # Rule to create modules.order file
 425 #
 426 # Create commands to either record .ko file or cat modules.order from
 427 # a subdirectory
 428 modorder-cmds =                                         \
 429         $(foreach m, $(modorder),                       \
 430                 $(if $(filter %/modules.order, $m),     \
 431                         cat $m;, echo kernel/$m;))
 432
 433 $(modorder-target): $(subdir-ym) FORCE
 434         $(Q)(cat /dev/null; $(modorder-cmds)) > $@
 435
 436 #
 437 # Rule to compile a set of .o files into one .a file
 438 #
 439 ifdef lib-target
 440 quiet_cmd_link_l_target = AR      $@
 441 cmd_link_l_target = rm -f $@; $(AR) rcs$(KBUILD_ARFLAGS) $@ $(lib-y)
 442
 443 $(lib-target): $(lib-y) FORCE
 444         $(call if_changed,link_l_target)
 445
 446 targets += $(lib-target)
 447 endif
 448
 449 #
 450 # Rule to link composite objects
 451 #
 452 #  Composite objects are specified in kbuild makefile as follows:
 453 #    <composite-object>-objs := <list of .o files>
 454 #  or
 455 #    <composite-object>-y    := <list of .o files>
 456 link_multi_deps =                     \
 457 $(filter $(addprefix $(obj)/,         \
 458 $($(subst $(obj)/,,$(@:.o=-objs)))    \
 459 $($(subst $(obj)/,,$(@:.o=-y)))), $^)
 460
 461 quiet_cmd_link_multi-y = LD      $@
 462 cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis)
 463
 464 quiet_cmd_link_multi-m = LD [M]  $@
 465 cmd_link_multi-m = $(cmd_link_multi-y)
 466
 467 $(multi-used-y): FORCE
 468         $(call if_changed,link_multi-y)
 469 $(call multi_depend, $(multi-used-y), .o, -objs -y)
 470
 471 $(multi-used-m): FORCE
 472         $(call if_changed,link_multi-m)
 473         @{ echo $(@:.o=.ko); echo $(link_multi_deps); } > $(MODVERDIR)/$(@F:.o=.mod)
 474 $(call multi_depend, $(multi-used-m), .o, -objs -y)
 475
 476 targets += $(multi-used-y) $(multi-used-m)
 477
 478
 479 # Descending
 480 # ---------------------------------------------------------------------------
 481
 482 PHONY += $(subdir-ym)
 483 $(subdir-ym):
 484         $(Q)$(MAKE) $(build)=$@
 485
 486 # Add FORCE to the prequisites of a target to force it to be always rebuilt.
 487 # ---------------------------------------------------------------------------
 488
 489 PHONY += FORCE
 490
 491 FORCE:
 492
 493 # Read all saved command lines and dependencies for the $(targets) we
 494 # may be building above, using $(if_changed{,_dep}). As an
 495 # optimization, we don't need to read them if the target does not
 496 # exist, we will rebuild anyway in that case.
 497
 498 targets := $(wildcard $(sort $(targets)))
 499 cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))
 500
 501 ifneq ($(cmd_files),)
 502   include $(cmd_files)
 503 endif
 504
 505 # Declare the contents of the .PHONY variable as phony.  We keep that
 506 # information in a variable se we can use it in if_changed and friends.
 507
 508 .PHONY: $(PHONY)