Makefile

   1 VERSION = 2
   2 PATCHLEVEL = 6
   3 SUBLEVEL = 25
   4 EXTRAVERSION = -rc1
   5 NAME = Arr Matey! A Hairy Bilge Rat!
   6
   7 # *DOCUMENTATION*
   8 # To see a list of typical targets execute "make help"
   9 # More info can be located in ./README
  10 # Comments in this file are targeted only to the developer, do not
  11 # expect to learn how to build the kernel reading this file.
  12
  13 # Do not:
  14 # o  use make's built-in rules and variables
  15 #    (this increases performance and avoids hard-to-debug behaviour);
  16 # o  print "Entering directory ...";
  17 MAKEFLAGS += -rR --no-print-directory
  18
  19 # We are using a recursive build, so we need to do a little thinking
  20 # to get the ordering right.
  21 #
  22 # Most importantly: sub-Makefiles should only ever modify files in
  23 # their own directory. If in some directory we have a dependency on
  24 # a file in another dir (which doesn't happen often, but it's often
  25 # unavoidable when linking the built-in.o targets which finally
  26 # turn into vmlinux), we will call a sub make in that other dir, and
  27 # after that we are sure that everything which is in that other dir
  28 # is now up to date.
  29 #
  30 # The only cases where we need to modify files which have global
  31 # effects are thus separated out and done before the recursive
  32 # descending is started. They are now explicitly listed as the
  33 # prepare rule.
  34
  35 # To put more focus on warnings, be less verbose as default
  36 # Use 'make V=1' to see the full commands
  37
  38 ifdef V
  39   ifeq ("$(origin V)", "command line")
  40     KBUILD_VERBOSE = $(V)
  41   endif
  42 endif
  43 ifndef KBUILD_VERBOSE
  44   KBUILD_VERBOSE = 0
  45 endif
  46
  47 # Call a source code checker (by default, "sparse") as part of the
  48 # C compilation.
  49 #
  50 # Use 'make C=1' to enable checking of only re-compiled files.
  51 # Use 'make C=2' to enable checking of *all* source files, regardless
  52 # of whether they are re-compiled or not.
  53 #
  54 # See the file "Documentation/sparse.txt" for more details, including
  55 # where to get the "sparse" utility.
  56
  57 ifdef C
  58   ifeq ("$(origin C)", "command line")
  59     KBUILD_CHECKSRC = $(C)
  60   endif
  61 endif
  62 ifndef KBUILD_CHECKSRC
  63   KBUILD_CHECKSRC = 0
  64 endif
  65
  66 # Use make M=dir to specify directory of external module to build
  67 # Old syntax make ... SUBDIRS=$PWD is still supported
  68 # Setting the environment variable KBUILD_EXTMOD take precedence
  69 ifdef SUBDIRS
  70   KBUILD_EXTMOD ?= $(SUBDIRS)
  71 endif
  72 ifdef M
  73   ifeq ("$(origin M)", "command line")
  74     KBUILD_EXTMOD := $(M)
  75   endif
  76 endif
  77
  78
  79 # kbuild supports saving output files in a separate directory.
  80 # To locate output files in a separate directory two syntaxes are supported.
  81 # In both cases the working directory must be the root of the kernel src.
  82 # 1) O=
  83 # Use "make O=dir/to/store/output/files/"
  84 #
  85 # 2) Set KBUILD_OUTPUT
  86 # Set the environment variable KBUILD_OUTPUT to point to the directory
  87 # where the output files shall be placed.
  88 # export KBUILD_OUTPUT=dir/to/store/output/files/
  89 # make
  90 #
  91 # The O= assignment takes precedence over the KBUILD_OUTPUT environment
  92 # variable.
  93
  94
  95 # KBUILD_SRC is set on invocation of make in OBJ directory
  96 # KBUILD_SRC is not intended to be used by the regular user (for now)
  97 ifeq ($(KBUILD_SRC),)
  98
  99 # OK, Make called in directory where kernel src resides
 100 # Do we want to locate output files in a separate directory?
 101 ifdef O
 102   ifeq ("$(origin O)", "command line")
 103     KBUILD_OUTPUT := $(O)
 104   endif
 105 endif
 106
 107 # That's our default target when none is given on the command line
 108 PHONY := _all
 109 _all:
 110
 111 # Cancel implicit rules on top Makefile
 112 $(CURDIR)/Makefile Makefile: ;
 113
 114 ifneq ($(KBUILD_OUTPUT),)
 115 # Invoke a second make in the output directory, passing relevant variables
 116 # check that the output directory actually exists
 117 saved-output := $(KBUILD_OUTPUT)
 118 KBUILD_OUTPUT := $(shell cd $(KBUILD_OUTPUT) && /bin/pwd)
 119 $(if $(KBUILD_OUTPUT),, \
 120      $(error output directory "$(saved-output)" does not exist))
 121
 122 PHONY += $(MAKECMDGOALS) sub-make
 123
 124 $(filter-out _all sub-make $(CURDIR)/Makefile, $(MAKECMDGOALS)) _all: sub-make
 125         $(Q)@:
 126
 127 sub-make: FORCE
 128         $(if $(KBUILD_VERBOSE:1=),@)$(MAKE) -C $(KBUILD_OUTPUT) \
 129         KBUILD_SRC=$(CURDIR) \
 130         KBUILD_EXTMOD="$(KBUILD_EXTMOD)" -f $(CURDIR)/Makefile \
 131         $(filter-out _all sub-make,$(MAKECMDGOALS))
 132
 133 # Leave processing to above invocation of make
 134 skip-makefile := 1
 135 endif # ifneq ($(KBUILD_OUTPUT),)
 136 endif # ifeq ($(KBUILD_SRC),)
 137
 138 # We process the rest of the Makefile if this is the final invocation of make
 139 ifeq ($(skip-makefile),)
 140
 141 # If building an external module we do not care about the all: rule
 142 # but instead _all depend on modules
 143 PHONY += all
 144 ifeq ($(KBUILD_EXTMOD),)
 145 _all: all
 146 else
 147 _all: modules
 148 endif
 149
 150 srctree         := $(if $(KBUILD_SRC),$(KBUILD_SRC),$(CURDIR))
 151 TOPDIR          := $(srctree)
 152 # FIXME - TOPDIR is obsolete, use srctree/objtree
 153 objtree         := $(CURDIR)
 154 src             := $(srctree)
 155 obj             := $(objtree)
 156
 157 VPATH           := $(srctree)$(if $(KBUILD_EXTMOD),:$(KBUILD_EXTMOD))
 158
 159 export srctree objtree VPATH TOPDIR
 160
 161
 162 # SUBARCH tells the usermode build what the underlying arch is.  That is set
 163 # first, and if a usermode build is happening, the "ARCH=um" on the command
 164 # line overrides the setting of ARCH below.  If a native build is happening,
 165 # then ARCH is assigned, getting whatever value it gets normally, and
 166 # SUBARCH is subsequently ignored.
 167
 168 SUBARCH := $(shell uname -m | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ \
 169                                   -e s/arm.*/arm/ -e s/sa110/arm/ \
 170                                   -e s/s390x/s390/ -e s/parisc64/parisc/ \
 171                                   -e s/ppc.*/powerpc/ -e s/mips.*/mips/ \
 172                                   -e s/sh.*/sh/ )
 173
 174 # Cross compiling and selecting different set of gcc/bin-utils
 175 # ---------------------------------------------------------------------------
 176 #
 177 # When performing cross compilation for other architectures ARCH shall be set
 178 # to the target architecture. (See arch/* for the possibilities).
 179 # ARCH can be set during invocation of make:
 180 # make ARCH=ia64
 181 # Another way is to have ARCH set in the environment.
 182 # The default ARCH is the host where make is executed.
 183
 184 # CROSS_COMPILE specify the prefix used for all executables used
 185 # during compilation. Only gcc and related bin-utils executables
 186 # are prefixed with $(CROSS_COMPILE).
 187 # CROSS_COMPILE can be set on the command line
 188 # make CROSS_COMPILE=ia64-linux-
 189 # Alternatively CROSS_COMPILE can be set in the environment.
 190 # Default value for CROSS_COMPILE is not to prefix executables
 191 # Note: Some architectures assign CROSS_COMPILE in their arch/*/Makefile
 192
 193 ARCH            ?= $(SUBARCH)
 194 CROSS_COMPILE   ?=
 195
 196 # Architecture as present in compile.h
 197 UTS_MACHINE     := $(ARCH)
 198 SRCARCH         := $(ARCH)
 199
 200 # Additional ARCH settings for x86
 201 ifeq ($(ARCH),i386)
 202         SRCARCH := x86
 203 endif
 204 ifeq ($(ARCH),x86_64)
 205         SRCARCH := x86
 206 endif
 207
 208 KCONFIG_CONFIG  ?= .config
 209
 210 # SHELL used by kbuild
 211 CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
 212           else if [ -x /bin/bash ]; then echo /bin/bash; \
 213           else echo sh; fi ; fi)
 214
 215 HOSTCC       = gcc
 216 HOSTCXX      = g++
 217 HOSTCFLAGS   = -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer
 218 HOSTCXXFLAGS = -O2
 219
 220 # Decide whether to build built-in, modular, or both.
 221 # Normally, just do built-in.
 222
 223 KBUILD_MODULES :=
 224 KBUILD_BUILTIN := 1
 225
 226 #       If we have only "make modules", don't compile built-in objects.
 227 #       When we're building modules with modversions, we need to consider
 228 #       the built-in objects during the descend as well, in order to
 229 #       make sure the checksums are up to date before we record them.
 230
 231 ifeq ($(MAKECMDGOALS),modules)
 232   KBUILD_BUILTIN := $(if $(CONFIG_MODVERSIONS),1)
 233 endif
 234
 235 #       If we have "make <whatever> modules", compile modules
 236 #       in addition to whatever we do anyway.
 237 #       Just "make" or "make all" shall build modules as well
 238
 239 ifneq ($(filter all _all modules,$(MAKECMDGOALS)),)
 240   KBUILD_MODULES := 1
 241 endif
 242
 243 ifeq ($(MAKECMDGOALS),)
 244   KBUILD_MODULES := 1
 245 endif
 246
 247 export KBUILD_MODULES KBUILD_BUILTIN
 248 export KBUILD_CHECKSRC KBUILD_SRC KBUILD_EXTMOD
 249
 250 # Beautify output
 251 # ---------------------------------------------------------------------------
 252 #
 253 # Normally, we echo the whole command before executing it. By making
 254 # that echo $($(quiet)$(cmd)), we now have the possibility to set
 255 # $(quiet) to choose other forms of output instead, e.g.
 256 #
 257 #         quiet_cmd_cc_o_c = Compiling $(RELDIR)/$@
 258 #         cmd_cc_o_c       = $(CC) $(c_flags) -c -o $@ $<
 259 #
 260 # If $(quiet) is empty, the whole command will be printed.
 261 # If it is set to "quiet_", only the short version will be printed.
 262 # If it is set to "silent_", nothing will be printed at all, since
 263 # the variable $(silent_cmd_cc_o_c) doesn't exist.
 264 #
 265 # A simple variant is to prefix commands with $(Q) - that's useful
 266 # for commands that shall be hidden in non-verbose mode.
 267 #
 268 #       $(Q)ln $@ :<
 269 #
 270 # If KBUILD_VERBOSE equals 0 then the above command will be hidden.
 271 # If KBUILD_VERBOSE equals 1 then the above command is displayed.
 272
 273 ifeq ($(KBUILD_VERBOSE),1)
 274   quiet =
 275   Q =
 276 else
 277   quiet=quiet_
 278   Q = @
 279 endif
 280
 281 # If the user is running make -s (silent mode), suppress echoing of
 282 # commands
 283
 284 ifneq ($(findstring s,$(MAKEFLAGS)),)
 285   quiet=silent_
 286 endif
 287
 288 export quiet Q KBUILD_VERBOSE
 289
 290
 291 # Look for make include files relative to root of kernel src
 292 MAKEFLAGS += --include-dir=$(srctree)
 293
 294 # We need some generic definitions (do not try to remake the file).
 295 $(srctree)/scripts/Kbuild.include: ;
 296 include $(srctree)/scripts/Kbuild.include
 297
 298 # Make variables (CC, etc...)
 299
 300 AS              = $(CROSS_COMPILE)as
 301 LD              = $(CROSS_COMPILE)ld
 302 CC              = $(CROSS_COMPILE)gcc
 303 CPP             = $(CC) -E
 304 AR              = $(CROSS_COMPILE)ar
 305 NM              = $(CROSS_COMPILE)nm
 306 STRIP           = $(CROSS_COMPILE)strip
 307 OBJCOPY         = $(CROSS_COMPILE)objcopy
 308 OBJDUMP         = $(CROSS_COMPILE)objdump
 309 AWK             = awk
 310 GENKSYMS        = scripts/genksyms/genksyms
 311 DEPMOD          = /sbin/depmod
 312 KALLSYMS        = scripts/kallsyms
 313 PERL            = perl
 314 CHECK           = sparse
 315
 316 CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ -Wbitwise $(CF)
 317 MODFLAGS        = -DMODULE
 318 CFLAGS_MODULE   = $(MODFLAGS)
 319 AFLAGS_MODULE   = $(MODFLAGS)
 320 LDFLAGS_MODULE  =
 321 CFLAGS_KERNEL   =
 322 AFLAGS_KERNEL   =
 323
 324
 325 # Use LINUXINCLUDE when you must reference the include/ directory.
 326 # Needed to be compatible with the O= option
 327 LINUXINCLUDE    := -Iinclude \
 328                    $(if $(KBUILD_SRC),-Iinclude2 -I$(srctree)/include) \
 329                    -include include/linux/autoconf.h
 330
 331 KBUILD_CPPFLAGS := -D__KERNEL__ $(LINUXINCLUDE)
 332
 333 KBUILD_CFLAGS   := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
 334                    -fno-strict-aliasing -fno-common \
 335                    -Werror-implicit-function-declaration
 336 KBUILD_AFLAGS   := -D__ASSEMBLY__
 337
 338 # Read KERNELRELEASE from include/config/kernel.release (if it exists)
 339 KERNELRELEASE = $(shell cat include/config/kernel.release 2> /dev/null)
 340 KERNELVERSION = $(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)
 341
 342 export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION
 343 export ARCH SRCARCH CONFIG_SHELL HOSTCC HOSTCFLAGS CROSS_COMPILE AS LD CC
 344 export CPP AR NM STRIP OBJCOPY OBJDUMP MAKE AWK GENKSYMS PERL UTS_MACHINE
 345 export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
 346
 347 export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS
 348 export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
 349 export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
 350
 351 # When compiling out-of-tree modules, put MODVERDIR in the module
 352 # tree rather than in the kernel tree. The kernel tree might
 353 # even be read-only.
 354 export MODVERDIR := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/).tmp_versions
 355
 356 # Files to ignore in find ... statements
 357
 358 RCS_FIND_IGNORE := \( -name SCCS -o -name BitKeeper -o -name .svn -o -name CVS -o -name .pc -o -name .hg -o -name .git \) -prune -o
 359 export RCS_TAR_IGNORE := --exclude SCCS --exclude BitKeeper --exclude .svn --exclude CVS --exclude .pc --exclude .hg --exclude .git
 360
 361 # ===========================================================================
 362 # Rules shared between *config targets and build targets
 363
 364 # Basic helpers built in scripts/
 365 PHONY += scripts_basic
 366 scripts_basic:
 367         $(Q)$(MAKE) $(build)=scripts/basic
 368
 369 # To avoid any implicit rule to kick in, define an empty command.
 370 scripts/basic/%: scripts_basic ;
 371
 372 PHONY += outputmakefile
 373 # outputmakefile generates a Makefile in the output directory, if using a
 374 # separate output directory. This allows convenient use of make in the
 375 # output directory.
 376 outputmakefile:
 377 ifneq ($(KBUILD_SRC),)
 378         $(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile \
 379             $(srctree) $(objtree) $(VERSION) $(PATCHLEVEL)
 380 endif
 381
 382 # To make sure we do not include .config for any of the *config targets
 383 # catch them early, and hand them over to scripts/kconfig/Makefile
 384 # It is allowed to specify more targets when calling make, including
 385 # mixing *config targets and build targets.
 386 # For example 'make oldconfig all'.
 387 # Detect when mixed targets is specified, and make a second invocation
 388 # of make so .config is not included in this case either (for *config).
 389
 390 no-dot-config-targets := clean mrproper distclean \
 391                          cscope TAGS tags help %docs check% \
 392                          include/linux/version.h headers_% \
 393                          kernelrelease kernelversion
 394
 395 config-targets := 0
 396 mixed-targets  := 0
 397 dot-config     := 1
 398
 399 ifneq ($(filter $(no-dot-config-targets), $(MAKECMDGOALS)),)
 400         ifeq ($(filter-out $(no-dot-config-targets), $(MAKECMDGOALS)),)
 401                 dot-config := 0
 402         endif
 403 endif
 404
 405 ifeq ($(KBUILD_EXTMOD),)
 406         ifneq ($(filter config %config,$(MAKECMDGOALS)),)
 407                 config-targets := 1
 408                 ifneq ($(filter-out config %config,$(MAKECMDGOALS)),)
 409                         mixed-targets := 1
 410                 endif
 411         endif
 412 endif
 413
 414 ifeq ($(mixed-targets),1)
 415 # ===========================================================================
 416 # We're called with mixed targets (*config and build targets).
 417 # Handle them one by one.
 418
 419 %:: FORCE
 420         $(Q)$(MAKE) -C $(srctree) KBUILD_SRC= $@
 421
 422 else
 423 ifeq ($(config-targets),1)
 424 # ===========================================================================
 425 # *config targets only - make sure prerequisites are updated, and descend
 426 # in scripts/kconfig to make the *config target
 427
 428 # Read arch specific Makefile to set KBUILD_DEFCONFIG as needed.
 429 # KBUILD_DEFCONFIG may point out an alternative default configuration
 430 # used for 'make defconfig'
 431 include $(srctree)/arch/$(SRCARCH)/Makefile
 432 export KBUILD_DEFCONFIG
 433
 434 config %config: scripts_basic outputmakefile FORCE
 435         $(Q)mkdir -p include/linux include/config
 436         $(Q)$(MAKE) $(build)=scripts/kconfig $@
 437
 438 else
 439 # ===========================================================================
 440 # Build targets only - this includes vmlinux, arch specific targets, clean
 441 # targets and others. In general all targets except *config targets.
 442
 443 ifeq ($(KBUILD_EXTMOD),)
 444 # Additional helpers built in scripts/
 445 # Carefully list dependencies so we do not try to build scripts twice
 446 # in parallel
 447 PHONY += scripts
 448 scripts: scripts_basic include/config/auto.conf
 449         $(Q)$(MAKE) $(build)=$(@)
 450
 451 # Objects we will link into vmlinux / subdirs we need to visit
 452 init-y          := init/
 453 drivers-y       := drivers/ sound/
 454 net-y           := net/
 455 libs-y          := lib/
 456 core-y          := usr/
 457 endif # KBUILD_EXTMOD
 458
 459 ifeq ($(dot-config),1)
 460 # Read in config
 461 -include include/config/auto.conf
 462
 463 ifeq ($(KBUILD_EXTMOD),)
 464 # Read in dependencies to all Kconfig* files, make sure to run
 465 # oldconfig if changes are detected.
 466 -include include/config/auto.conf.cmd
 467
 468 # To avoid any implicit rule to kick in, define an empty command
 469 $(KCONFIG_CONFIG) include/config/auto.conf.cmd: ;
 470
 471 # If .config is newer than include/config/auto.conf, someone tinkered
 472 # with it and forgot to run make oldconfig.
 473 # if auto.conf.cmd is missing then we are probably in a cleaned tree so
 474 # we execute the config step to be sure to catch updated Kconfig files
 475 include/config/auto.conf: $(KCONFIG_CONFIG) include/config/auto.conf.cmd
 476         $(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
 477 else
 478 # external modules needs include/linux/autoconf.h and include/config/auto.conf
 479 # but do not care if they are up-to-date. Use auto.conf to trigger the test
 480 PHONY += include/config/auto.conf
 481
 482 include/config/auto.conf:
 483         $(Q)test -e include/linux/autoconf.h -a -e $@ || (              \
 484         echo;                                                           \
 485         echo "  ERROR: Kernel configuration is invalid.";               \
 486         echo "         include/linux/autoconf.h or $@ are missing.";    \
 487         echo "         Run 'make oldconfig && make prepare' on kernel src to fix it.";  \
 488         echo;                                                           \
 489         /bin/false)
 490
 491 endif # KBUILD_EXTMOD
 492
 493 else
 494 # Dummy target needed, because used as prerequisite
 495 include/config/auto.conf: ;
 496 endif # $(dot-config)
 497
 498 # The all: target is the default when no target is given on the
 499 # command line.
 500 # This allow a user to issue only 'make' to build a kernel including modules
 501 # Defaults vmlinux but it is usually overridden in the arch makefile
 502 all: vmlinux
 503
 504 ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
 505 KBUILD_CFLAGS   += -Os
 506 else
 507 KBUILD_CFLAGS   += -O2
 508 endif
 509
 510 include $(srctree)/arch/$(SRCARCH)/Makefile
 511
 512 ifdef CONFIG_FRAME_POINTER
 513 KBUILD_CFLAGS   += -fno-omit-frame-pointer -fno-optimize-sibling-calls
 514 else
 515 KBUILD_CFLAGS   += -fomit-frame-pointer
 516 endif
 517
 518 ifdef CONFIG_DEBUG_INFO
 519 KBUILD_CFLAGS   += -g
 520 KBUILD_AFLAGS   += -gdwarf-2
 521 endif
 522
 523 # We trigger additional mismatches with less inlining
 524 ifdef CONFIG_DEBUG_SECTION_MISMATCH
 525 KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
 526 endif
 527
 528 # Force gcc to behave correct even for buggy distributions
 529 KBUILD_CFLAGS         += $(call cc-option, -fno-stack-protector)
 530
 531 # arch Makefile may override CC so keep this after arch Makefile is included
 532 NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
 533 CHECKFLAGS     += $(NOSTDINC_FLAGS)
 534
 535 # warn about C99 declaration after statement
 536 KBUILD_CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)
 537
 538 # disable pointer signed / unsigned warnings in gcc 4.0
 539 KBUILD_CFLAGS += $(call cc-option,-Wno-pointer-sign,)
 540
 541 # Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
 542 # But warn user when we do so
 543 warn-assign = \
 544 $(warning "WARNING: Appending $$K$(1) ($(K$(1))) from $(origin K$(1)) to kernel $$$(1)")
 545
 546 ifneq ($(KCPPFLAGS),)
 547         $(call warn-assign,CPPFLAGS)
 548         KBUILD_CPPFLAGS += $(KCPPFLAGS)
 549 endif
 550 ifneq ($(KAFLAGS),)
 551         $(call warn-assign,AFLAGS)
 552         KBUILD_AFLAGS += $(KAFLAGS)
 553 endif
 554 ifneq ($(KCFLAGS),)
 555         $(call warn-assign,CFLAGS)
 556         KBUILD_CFLAGS += $(KCFLAGS)
 557 endif
 558
 559 # Use --build-id when available.
 560 LDFLAGS_BUILD_ID = $(patsubst -Wl$(comma)%,%,\
 561                               $(call ld-option, -Wl$(comma)--build-id,))
 562 LDFLAGS_MODULE += $(LDFLAGS_BUILD_ID)
 563 LDFLAGS_vmlinux += $(LDFLAGS_BUILD_ID)
 564
 565 # Default kernel image to build when no specific target is given.
 566 # KBUILD_IMAGE may be overruled on the command line or
 567 # set in the environment
 568 # Also any assignments in arch/$(ARCH)/Makefile take precedence over
 569 # this default value
 570 export KBUILD_IMAGE ?= vmlinux
 571
 572 #
 573 # INSTALL_PATH specifies where to place the updated kernel and system map
 574 # images. Default is /boot, but you can set it to other values
 575 export  INSTALL_PATH ?= /boot
 576
 577 #
 578 # INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
 579 # relocations required by build roots.  This is not defined in the
 580 # makefile but the argument can be passed to make if needed.
 581 #
 582
 583 MODLIB  = $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
 584 export MODLIB
 585
 586 #
 587 #  INSTALL_MOD_STRIP, if defined, will cause modules to be
 588 #  stripped after they are installed.  If INSTALL_MOD_STRIP is '1', then
 589 #  the default option --strip-debug will be used.  Otherwise,
 590 #  INSTALL_MOD_STRIP will used as the options to the strip command.
 591
 592 ifdef INSTALL_MOD_STRIP
 593 ifeq ($(INSTALL_MOD_STRIP),1)
 594 mod_strip_cmd = $(STRIP) --strip-debug
 595 else
 596 mod_strip_cmd = $(STRIP) $(INSTALL_MOD_STRIP)
 597 endif # INSTALL_MOD_STRIP=1
 598 else
 599 mod_strip_cmd = true
 600 endif # INSTALL_MOD_STRIP
 601 export mod_strip_cmd
 602
 603
 604 ifeq ($(KBUILD_EXTMOD),)
 605 core-y          += kernel/ mm/ fs/ ipc/ security/ crypto/ block/
 606
 607 vmlinux-dirs    := $(patsubst %/,%,$(filter %/, $(init-y) $(init-m) \
 608                      $(core-y) $(core-m) $(drivers-y) $(drivers-m) \
 609                      $(net-y) $(net-m) $(libs-y) $(libs-m)))
 610
 611 vmlinux-alldirs := $(sort $(vmlinux-dirs) $(patsubst %/,%,$(filter %/, \
 612                      $(init-n) $(init-) \
 613                      $(core-n) $(core-) $(drivers-n) $(drivers-) \
 614                      $(net-n)  $(net-)  $(libs-n)    $(libs-))))
 615
 616 init-y          := $(patsubst %/, %/built-in.o, $(init-y))
 617 core-y          := $(patsubst %/, %/built-in.o, $(core-y))
 618 drivers-y       := $(patsubst %/, %/built-in.o, $(drivers-y))
 619 net-y           := $(patsubst %/, %/built-in.o, $(net-y))
 620 libs-y1         := $(patsubst %/, %/lib.a, $(libs-y))
 621 libs-y2         := $(patsubst %/, %/built-in.o, $(libs-y))
 622 libs-y          := $(libs-y1) $(libs-y2)
 623
 624 # Build vmlinux
 625 # ---------------------------------------------------------------------------
 626 # vmlinux is built from the objects selected by $(vmlinux-init) and
 627 # $(vmlinux-main). Most are built-in.o files from top-level directories
 628 # in the kernel tree, others are specified in arch/$(ARCH)/Makefile.
 629 # Ordering when linking is important, and $(vmlinux-init) must be first.
 630 #
 631 # vmlinux
 632 #   ^
 633 #   |
 634 #   +-< $(vmlinux-init)
 635 #   |   +--< init/version.o + more
 636 #   |
 637 #   +--< $(vmlinux-main)
 638 #   |    +--< driver/built-in.o mm/built-in.o + more
 639 #   |
 640 #   +-< kallsyms.o (see description in CONFIG_KALLSYMS section)
 641 #
 642 # vmlinux version (uname -v) cannot be updated during normal
 643 # descending-into-subdirs phase since we do not yet know if we need to
 644 # update vmlinux.
 645 # Therefore this step is delayed until just before final link of vmlinux -
 646 # except in the kallsyms case where it is done just before adding the
 647 # symbols to the kernel.
 648 #
 649 # System.map is generated to document addresses of all kernel symbols
 650
 651 vmlinux-init := $(head-y) $(init-y)
 652 vmlinux-main := $(core-y) $(libs-y) $(drivers-y) $(net-y)
 653 vmlinux-all  := $(vmlinux-init) $(vmlinux-main)
 654 vmlinux-lds  := arch/$(SRCARCH)/kernel/vmlinux.lds
 655 export KBUILD_VMLINUX_OBJS := $(vmlinux-all)
 656
 657 # Rule to link vmlinux - also used during CONFIG_KALLSYMS
 658 # May be overridden by arch/$(ARCH)/Makefile
 659 quiet_cmd_vmlinux__ ?= LD      $@
 660       cmd_vmlinux__ ?= $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) -o $@ \
 661       -T $(vmlinux-lds) $(vmlinux-init)                          \
 662       --start-group $(vmlinux-main) --end-group                  \
 663       $(filter-out $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) vmlinux.o FORCE ,$^)
 664
 665 # Generate new vmlinux version
 666 quiet_cmd_vmlinux_version = GEN     .version
 667       cmd_vmlinux_version = set -e;                     \
 668         if [ ! -r .version ]; then                      \
 669           rm -f .version;                               \
 670           echo 1 >.version;                             \
 671         else                                            \
 672           mv .version .old_version;                     \
 673           expr 0$$(cat .old_version) + 1 >.version;     \
 674         fi;                                             \
 675         $(MAKE) $(build)=init
 676
 677 # Generate System.map
 678 quiet_cmd_sysmap = SYSMAP
 679       cmd_sysmap = $(CONFIG_SHELL) $(srctree)/scripts/mksysmap
 680
 681 # Link of vmlinux
 682 # If CONFIG_KALLSYMS is set .version is already updated
 683 # Generate System.map and verify that the content is consistent
 684 # Use + in front of the vmlinux_version rule to silent warning with make -j2
 685 # First command is ':' to allow us to use + in front of the rule
 686 define rule_vmlinux__
 687         :
 688         $(if $(CONFIG_KALLSYMS),,+$(call cmd,vmlinux_version))
 689
 690         $(call cmd,vmlinux__)
 691         $(Q)echo 'cmd_$@ := $(cmd_vmlinux__)' > $(@D)/.$(@F).cmd
 692
 693         $(Q)$(if $($(quiet)cmd_sysmap),                                      \
 694           echo '  $($(quiet)cmd_sysmap)  System.map' &&)                     \
 695         $(cmd_sysmap) $@ System.map;                                         \
 696         if [ $$? -ne 0 ]; then                                               \
 697                 rm -f $@;                                                    \
 698                 /bin/false;                                                  \
 699         fi;
 700         $(verify_kallsyms)
 701 endef
 702
 703
 704 ifdef CONFIG_KALLSYMS
 705 # Generate section listing all symbols and add it into vmlinux $(kallsyms.o)
 706 # It's a three stage process:
 707 # o .tmp_vmlinux1 has all symbols and sections, but __kallsyms is
 708 #   empty
 709 #   Running kallsyms on that gives us .tmp_kallsyms1.o with
 710 #   the right size - vmlinux version (uname -v) is updated during this step
 711 # o .tmp_vmlinux2 now has a __kallsyms section of the right size,
 712 #   but due to the added section, some addresses have shifted.
 713 #   From here, we generate a correct .tmp_kallsyms2.o
 714 # o The correct .tmp_kallsyms2.o is linked into the final vmlinux.
 715 # o Verify that the System.map from vmlinux matches the map from
 716 #   .tmp_vmlinux2, just in case we did not generate kallsyms correctly.
 717 # o If CONFIG_KALLSYMS_EXTRA_PASS is set, do an extra pass using
 718 #   .tmp_vmlinux3 and .tmp_kallsyms3.o.  This is only meant as a
 719 #   temporary bypass to allow the kernel to be built while the
 720 #   maintainers work out what went wrong with kallsyms.
 721
 722 ifdef CONFIG_KALLSYMS_EXTRA_PASS
 723 last_kallsyms := 3
 724 else
 725 last_kallsyms := 2
 726 endif
 727
 728 kallsyms.o := .tmp_kallsyms$(last_kallsyms).o
 729
 730 define verify_kallsyms
 731         $(Q)$(if $($(quiet)cmd_sysmap),                                      \
 732           echo '  $($(quiet)cmd_sysmap)  .tmp_System.map' &&)                \
 733           $(cmd_sysmap) .tmp_vmlinux$(last_kallsyms) .tmp_System.map
 734         $(Q)cmp -s System.map .tmp_System.map ||                             \
 735                 (echo Inconsistent kallsyms data;                            \
 736                  echo Try setting CONFIG_KALLSYMS_EXTRA_PASS;                \
 737                  rm .tmp_kallsyms* ; /bin/false )
 738 endef
 739
 740 # Update vmlinux version before link
 741 # Use + in front of this rule to silent warning about make -j1
 742 # First command is ':' to allow us to use + in front of this rule
 743 cmd_ksym_ld = $(cmd_vmlinux__)
 744 define rule_ksym_ld
 745         :
 746         +$(call cmd,vmlinux_version)
 747         $(call cmd,vmlinux__)
 748         $(Q)echo 'cmd_$@ := $(cmd_vmlinux__)' > $(@D)/.$(@F).cmd
 749 endef
 750
 751 # Generate .S file with all kernel symbols
 752 quiet_cmd_kallsyms = KSYM    $@
 753       cmd_kallsyms = $(NM) -n $< | $(KALLSYMS) \
 754                      $(if $(CONFIG_KALLSYMS_ALL),--all-symbols) > $@
 755
 756 .tmp_kallsyms1.o .tmp_kallsyms2.o .tmp_kallsyms3.o: %.o: %.S scripts FORCE
 757         $(call if_changed_dep,as_o_S)
 758
 759 .tmp_kallsyms%.S: .tmp_vmlinux% $(KALLSYMS)
 760         $(call cmd,kallsyms)
 761
 762 # .tmp_vmlinux1 must be complete except kallsyms, so update vmlinux version
 763 .tmp_vmlinux1: $(vmlinux-lds) $(vmlinux-all) FORCE
 764         $(call if_changed_rule,ksym_ld)
 765
 766 .tmp_vmlinux2: $(vmlinux-lds) $(vmlinux-all) .tmp_kallsyms1.o FORCE
 767         $(call if_changed,vmlinux__)
 768
 769 .tmp_vmlinux3: $(vmlinux-lds) $(vmlinux-all) .tmp_kallsyms2.o FORCE
 770         $(call if_changed,vmlinux__)
 771
 772 # Needs to visit scripts/ before $(KALLSYMS) can be used.
 773 $(KALLSYMS): scripts ;
 774
 775 # Generate some data for debugging strange kallsyms problems
 776 debug_kallsyms: .tmp_map$(last_kallsyms)
 777
 778 .tmp_map%: .tmp_vmlinux% FORCE
 779         ($(OBJDUMP) -h $< | $(AWK) '/^ +[0-9]/{print $$4 " 0 " $$2}'; $(NM) $<) | sort > $@
 780
 781 .tmp_map3: .tmp_map2
 782
 783 .tmp_map2: .tmp_map1
 784
 785 endif # ifdef CONFIG_KALLSYMS
 786
 787 # Do modpost on a prelinked vmlinux. The finally linked vmlinux has
 788 # relevant sections renamed as per the linker script.
 789 quiet_cmd_vmlinux-modpost = LD      $@
 790       cmd_vmlinux-modpost = $(LD) $(LDFLAGS) -r -o $@                          \
 791          $(vmlinux-init) --start-group $(vmlinux-main) --end-group             \
 792          $(filter-out $(vmlinux-init) $(vmlinux-main) $(vmlinux-lds) FORCE ,$^)
 793 define rule_vmlinux-modpost
 794         :
 795         +$(call cmd,vmlinux-modpost)
 796         $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost $@
 797         $(Q)echo 'cmd_$@ := $(cmd_vmlinux-modpost)' > $(dot-target).cmd
 798 endef
 799
 800 # vmlinux image - including updated kernel symbols
 801 vmlinux: $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) vmlinux.o $(kallsyms.o) FORCE
 802 ifdef CONFIG_HEADERS_CHECK
 803         $(Q)$(MAKE) -f $(srctree)/Makefile headers_check
 804 endif
 805 ifdef CONFIG_SAMPLES
 806         $(Q)$(MAKE) $(build)=samples
 807 endif
 808         $(call vmlinux-modpost)
 809         $(call if_changed_rule,vmlinux__)
 810         $(Q)rm -f .old_version
 811
 812 # build vmlinux.o first to catch section mismatch errors early
 813 $(kallsyms.o): vmlinux.o
 814 vmlinux.o: $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) FORCE
 815         $(call if_changed_rule,vmlinux-modpost)
 816
 817 # The actual objects are generated when descending,
 818 # make sure no implicit rule kicks in
 819 $(sort $(vmlinux-init) $(vmlinux-main)) $(vmlinux-lds): $(vmlinux-dirs) ;
 820
 821 # Handle descending into subdirectories listed in $(vmlinux-dirs)
 822 # Preset locale variables to speed up the build process. Limit locale
 823 # tweaks to this spot to avoid wrong language settings when running
 824 # make menuconfig etc.
 825 # Error messages still appears in the original language
 826
 827 PHONY += $(vmlinux-dirs)
 828 $(vmlinux-dirs): prepare scripts
 829         $(Q)$(MAKE) $(build)=$@
 830
 831 # Build the kernel release string
 832 #
 833 # The KERNELRELEASE value built here is stored in the file
 834 # include/config/kernel.release, and is used when executing several
 835 # make targets, such as "make install" or "make modules_install."
 836 #
 837 # The eventual kernel release string consists of the following fields,
 838 # shown in a hierarchical format to show how smaller parts are concatenated
 839 # to form the larger and final value, with values coming from places like
 840 # the Makefile, kernel config options, make command line options and/or
 841 # SCM tag information.
 842 #
 843 #       $(KERNELVERSION)
 844 #         $(VERSION)                    eg, 2
 845 #         $(PATCHLEVEL)                 eg, 6
 846 #         $(SUBLEVEL)                   eg, 18
 847 #         $(EXTRAVERSION)               eg, -rc6
 848 #       $(localver-full)
 849 #         $(localver)
 850 #           localversion*               (files without backups, containing '~')
 851 #           $(CONFIG_LOCALVERSION)      (from kernel config setting)
 852 #         $(localver-auto)              (only if CONFIG_LOCALVERSION_AUTO is set)
 853 #           ./scripts/setlocalversion   (SCM tag, if one exists)
 854 #           $(LOCALVERSION)             (from make command line if provided)
 855 #
 856 #  Note how the final $(localver-auto) string is included *only* if the
 857 # kernel config option CONFIG_LOCALVERSION_AUTO is selected.  Also, at the
 858 # moment, only git is supported but other SCMs can edit the script
 859 # scripts/setlocalversion and add the appropriate checks as needed.
 860
 861 pattern = ".*/localversion[^~]*"
 862 string  = $(shell cat /dev/null \
 863            `find $(objtree) $(srctree) -maxdepth 1 -regex $(pattern) | sort -u`)
 864
 865 localver = $(subst $(space),, $(string) \
 866                               $(patsubst "%",%,$(CONFIG_LOCALVERSION)))
 867
 868 # If CONFIG_LOCALVERSION_AUTO is set scripts/setlocalversion is called
 869 # and if the SCM is know a tag from the SCM is appended.
 870 # The appended tag is determined by the SCM used.
 871 #
 872 # Currently, only git is supported.
 873 # Other SCMs can edit scripts/setlocalversion and add the appropriate
 874 # checks as needed.
 875 ifdef CONFIG_LOCALVERSION_AUTO
 876         _localver-auto = $(shell $(CONFIG_SHELL) \
 877                           $(srctree)/scripts/setlocalversion $(srctree))
 878         localver-auto  = $(LOCALVERSION)$(_localver-auto)
 879 endif
 880
 881 localver-full = $(localver)$(localver-auto)
 882
 883 # Store (new) KERNELRELASE string in include/config/kernel.release
 884 kernelrelease = $(KERNELVERSION)$(localver-full)
 885 include/config/kernel.release: include/config/auto.conf FORCE
 886         $(Q)rm -f $@
 887         $(Q)echo $(kernelrelease) > $@
 888
 889
 890 # Things we need to do before we recursively start building the kernel
 891 # or the modules are listed in "prepare".
 892 # A multi level approach is used. prepareN is processed before prepareN-1.
 893 # archprepare is used in arch Makefiles and when processed asm symlink,
 894 # version.h and scripts_basic is processed / created.
 895
 896 # Listed in dependency order
 897 PHONY += prepare archprepare prepare0 prepare1 prepare2 prepare3
 898
 899 # prepare3 is used to check if we are building in a separate output directory,
 900 # and if so do:
 901 # 1) Check that make has not been executed in the kernel src $(srctree)
 902 # 2) Create the include2 directory, used for the second asm symlink
 903 prepare3: include/config/kernel.release
 904 ifneq ($(KBUILD_SRC),)
 905         @echo '  Using $(srctree) as source for kernel'
 906         $(Q)if [ -f $(srctree)/.config -o -d $(srctree)/include/config ]; then \
 907                 echo "  $(srctree) is not clean, please run 'make mrproper'";\
 908                 echo "  in the '$(srctree)' directory.";\
 909                 /bin/false; \
 910         fi;
 911         $(Q)if [ ! -d include2 ]; then mkdir -p include2; fi;
 912         $(Q)ln -fsn $(srctree)/include/asm-$(SRCARCH) include2/asm
 913 endif
 914
 915 # prepare2 creates a makefile if using a separate output directory
 916 prepare2: prepare3 outputmakefile
 917
 918 prepare1: prepare2 include/linux/version.h include/linux/utsrelease.h \
 919                    include/asm include/config/auto.conf
 920         $(cmd_crmodverdir)
 921
 922 archprepare: prepare1 scripts_basic
 923
 924 prepare0: archprepare FORCE
 925         $(Q)$(MAKE) $(build)=.
 926         $(Q)$(MAKE) $(build)=. missing-syscalls
 927
 928 # All the preparing..
 929 prepare: prepare0
 930
 931 # Leave this as default for preprocessing vmlinux.lds.S, which is now
 932 # done in arch/$(ARCH)/kernel/Makefile
 933
 934 export CPPFLAGS_vmlinux.lds += -P -C -U$(ARCH)
 935
 936 # The asm symlink changes when $(ARCH) changes.
 937 # Detect this and ask user to run make mrproper
 938
 939 include/asm: FORCE
 940         $(Q)set -e; asmlink=`readlink include/asm | cut -d '-' -f 2`;   \
 941         if [ -L include/asm ]; then                                     \
 942                 if [ "$$asmlink" != "$(SRCARCH)" ]; then                \
 943                         echo "ERROR: the symlink $@ points to asm-$$asmlink but asm-$(SRCARCH) was expected"; \
 944                         echo "       set ARCH or save .config and run 'make mrproper' to fix it";             \
 945                         exit 1;                                         \
 946                 fi;                                                     \
 947         else                                                            \
 948                 echo '  SYMLINK $@ -> include/asm-$(SRCARCH)';          \
 949                 if [ ! -d include ]; then                               \
 950                         mkdir -p include;                               \
 951                 fi;                                                     \
 952                 ln -fsn asm-$(SRCARCH) $@;                              \
 953         fi
 954
 955 # Generate some files
 956 # ---------------------------------------------------------------------------
 957
 958 # KERNELRELEASE can change from a few different places, meaning version.h
 959 # needs to be updated, so this check is forced on all builds
 960
 961 uts_len := 64
 962 define filechk_utsrelease.h
 963         if [ `echo -n "$(KERNELRELEASE)" | wc -c ` -gt $(uts_len) ]; then \
 964           echo '"$(KERNELRELEASE)" exceeds $(uts_len) characters' >&2;    \
 965           exit 1;                                                         \
 966         fi;                                                               \
 967         (echo \#define UTS_RELEASE \"$(KERNELRELEASE)\";)
 968 endef
 969
 970 define filechk_version.h
 971         (echo \#define LINUX_VERSION_CODE $(shell                             \
 972         expr $(VERSION) \* 65536 + $(PATCHLEVEL) \* 256 + $(SUBLEVEL));     \
 973         echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))';)
 974 endef
 975
 976 include/linux/version.h: $(srctree)/Makefile FORCE
 977         $(call filechk,version.h)
 978
 979 include/linux/utsrelease.h: include/config/kernel.release FORCE
 980         $(call filechk,utsrelease.h)
 981
 982 # ---------------------------------------------------------------------------
 983
 984 PHONY += depend dep
 985 depend dep:
 986         @echo '*** Warning: make $@ is unnecessary now.'
 987
 988 # ---------------------------------------------------------------------------
 989 # Kernel headers
 990 INSTALL_HDR_PATH=$(objtree)/usr
 991 export INSTALL_HDR_PATH
 992
 993 HDRFILTER=generic i386 x86_64
 994 HDRARCHES=$(filter-out $(HDRFILTER),$(patsubst $(srctree)/include/asm-%/Kbuild,%,$(wildcard $(srctree)/include/asm-*/Kbuild)))
 995
 996 PHONY += headers_install_all
 997 headers_install_all: include/linux/version.h scripts_basic FORCE
 998         $(Q)$(MAKE) $(build)=scripts scripts/unifdef
 999         $(Q)for arch in $(HDRARCHES); do \
1000          $(MAKE) ARCH=$$arch -f $(srctree)/scripts/Makefile.headersinst obj=include BIASMDIR=-bi-$$arch ;\
1001          done
1002
1003 PHONY += headers_install
1004 headers_install: include/linux/version.h scripts_basic FORCE
1005         @if [ ! -r $(srctree)/include/asm-$(SRCARCH)/Kbuild ]; then \
1006           echo '*** Error: Headers not exportable for this architecture ($(SRCARCH))'; \
1007           exit 1 ; fi
1008         $(Q)$(MAKE) $(build)=scripts scripts/unifdef
1009         $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.headersinst ARCH=$(SRCARCH) obj=include
1010
1011 PHONY += headers_check_all
1012 headers_check_all: headers_install_all
1013         $(Q)for arch in $(HDRARCHES); do \
1014          $(MAKE) ARCH=$$arch -f $(srctree)/scripts/Makefile.headersinst obj=include BIASMDIR=-bi-$$arch HDRCHECK=1 ;\
1015          done
1016
1017 PHONY += headers_check
1018 headers_check: headers_install
1019         $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.headersinst ARCH=$(SRCARCH) obj=include HDRCHECK=1
1020
1021 # ---------------------------------------------------------------------------
1022 # Modules
1023
1024 ifdef CONFIG_MODULES
1025
1026 # By default, build modules as well
1027
1028 all: modules
1029
1030 #       Build modules
1031 #
1032 #       A module can be listed more than once in obj-m resulting in
1033 #       duplicate lines in modules.order files.  Those are removed
1034 #       using awk while concatenating to the final file.
1035
1036 PHONY += modules
1037 modules: $(vmlinux-dirs) $(if $(KBUILD_BUILTIN),vmlinux)
1038         $(Q)$(AWK) '!x[$$0]++' $(vmlinux-dirs:%=$(objtree)/%/modules.order) > $(objtree)/modules.order
1039         @echo '  Building modules, stage 2.';
1040         $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
1041
1042
1043 # Target to prepare building external modules
1044 PHONY += modules_prepare
1045 modules_prepare: prepare scripts
1046
1047 # Target to install modules
1048 PHONY += modules_install
1049 modules_install: _modinst_ _modinst_post
1050
1051 PHONY += _modinst_
1052 _modinst_:
1053         @if [ -z "`$(DEPMOD) -V 2>/dev/null | grep module-init-tools`" ]; then \
1054                 echo "Warning: you may need to install module-init-tools"; \
1055                 echo "See http://www.codemonkey.org.uk/docs/post-halloween-2.6.txt";\
1056                 sleep 1; \
1057         fi
1058         @rm -rf $(MODLIB)/kernel
1059         @rm -f $(MODLIB)/source
1060         @mkdir -p $(MODLIB)/kernel
1061         @ln -s $(srctree) $(MODLIB)/source
1062         @if [ ! $(objtree) -ef  $(MODLIB)/build ]; then \
1063                 rm -f $(MODLIB)/build ; \
1064                 ln -s $(objtree) $(MODLIB)/build ; \
1065         fi
1066         @cp -f $(objtree)/modules.order $(MODLIB)/
1067         $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst
1068
1069 # This depmod is only for convenience to give the initial
1070 # boot a modules.dep even before / is mounted read-write.  However the
1071 # boot script depmod is the master version.
1072 PHONY += _modinst_post
1073 _modinst_post: _modinst_
1074         $(call cmd,depmod)
1075
1076 else # CONFIG_MODULES
1077
1078 # Modules not configured
1079 # ---------------------------------------------------------------------------
1080
1081 modules modules_install: FORCE
1082         @echo
1083         @echo "The present kernel configuration has modules disabled."
1084         @echo "Type 'make config' and enable loadable module support."
1085         @echo "Then build a kernel with module support enabled."
1086         @echo
1087         @exit 1
1088
1089 endif # CONFIG_MODULES
1090
1091 ###
1092 # Cleaning is done on three levels.
1093 # make clean     Delete most generated files
1094 #                Leave enough to build external modules
1095 # make mrproper  Delete the current configuration, and all generated files
1096 # make distclean Remove editor backup files, patch leftover files and the like
1097
1098 # Directories & files removed with 'make clean'
1099 CLEAN_DIRS  += $(MODVERDIR)
1100 CLEAN_FILES +=  vmlinux System.map \
1101                 .tmp_kallsyms* .tmp_version .tmp_vmlinux* .tmp_System.map
1102
1103 # Directories & files removed with 'make mrproper'
1104 MRPROPER_DIRS  += include/config include2 usr/include
1105 MRPROPER_FILES += .config .config.old include/asm .version .old_version \
1106                   include/linux/autoconf.h include/linux/version.h      \
1107                   include/linux/utsrelease.h                            \
1108                   Module.symvers tags TAGS cscope*
1109
1110 # clean - Delete most, but leave enough to build external modules
1111 #
1112 clean: rm-dirs  := $(CLEAN_DIRS)
1113 clean: rm-files := $(CLEAN_FILES)
1114 clean-dirs      := $(addprefix _clean_,$(srctree) $(vmlinux-alldirs))
1115
1116 PHONY += $(clean-dirs) clean archclean
1117 $(clean-dirs):
1118         $(Q)$(MAKE) $(clean)=$(patsubst _clean_%,%,$@)
1119
1120 clean: archclean $(clean-dirs)
1121         $(call cmd,rmdirs)
1122         $(call cmd,rmfiles)
1123         @find . $(RCS_FIND_IGNORE) \
1124                 \( -name '*.[oas]' -o -name '*.ko' -o -name '.*.cmd' \
1125                 -o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
1126                 -o -name '*.symtypes' -o -name 'modules.order' \) \
1127                 -type f -print | xargs rm -f
1128
1129 # mrproper - Delete all generated files, including .config
1130 #
1131 mrproper: rm-dirs  := $(wildcard $(MRPROPER_DIRS))
1132 mrproper: rm-files := $(wildcard $(MRPROPER_FILES))
1133 mrproper-dirs      := $(addprefix _mrproper_,Documentation/DocBook scripts)
1134
1135 PHONY += $(mrproper-dirs) mrproper archmrproper
1136 $(mrproper-dirs):
1137         $(Q)$(MAKE) $(clean)=$(patsubst _mrproper_%,%,$@)
1138
1139 mrproper: clean archmrproper $(mrproper-dirs)
1140         $(call cmd,rmdirs)
1141         $(call cmd,rmfiles)
1142
1143 # distclean
1144 #
1145 PHONY += distclean
1146
1147 distclean: mrproper
1148         @find $(srctree) $(RCS_FIND_IGNORE) \
1149                 \( -name '*.orig' -o -name '*.rej' -o -name '*~' \
1150                 -o -name '*.bak' -o -name '#*#' -o -name '.*.orig' \
1151                 -o -name '.*.rej' -o -size 0 \
1152                 -o -name '*%' -o -name '.*.cmd' -o -name 'core' \) \
1153                 -type f -print | xargs rm -f
1154
1155
1156 # Packaging of the kernel to various formats
1157 # ---------------------------------------------------------------------------
1158 # rpm target kept for backward compatibility
1159 package-dir     := $(srctree)/scripts/package
1160
1161 %pkg: include/config/kernel.release FORCE
1162         $(Q)$(MAKE) $(build)=$(package-dir) $@
1163 rpm: include/config/kernel.release FORCE
1164         $(Q)$(MAKE) $(build)=$(package-dir) $@
1165
1166
1167 # Brief documentation of the typical targets used
1168 # ---------------------------------------------------------------------------
1169
1170 boards := $(wildcard $(srctree)/arch/$(ARCH)/configs/*_defconfig)
1171 boards := $(notdir $(boards))
1172
1173 help:
1174         @echo  'Cleaning targets:'
1175         @echo  '  clean           - Remove most generated files but keep the config and'
1176         @echo  '                    enough build support to build external modules'
1177         @echo  '  mrproper        - Remove all generated files + config + various backup files'
1178         @echo  '  distclean       - mrproper + remove editor backup and patch files'
1179         @echo  ''
1180         @echo  'Configuration targets:'
1181         @$(MAKE) -f $(srctree)/scripts/kconfig/Makefile help
1182         @echo  ''
1183         @echo  'Other generic targets:'
1184         @echo  '  all             - Build all targets marked with [*]'
1185         @echo  '* vmlinux         - Build the bare kernel'
1186         @echo  '* modules         - Build all modules'
1187         @echo  '  modules_install - Install all modules to INSTALL_MOD_PATH (default: /)'
1188         @echo  '  dir/            - Build all files in dir and below'
1189         @echo  '  dir/file.[ois]  - Build specified target only'
1190         @echo  '  dir/file.ko     - Build module including final link'
1191         @echo  '  prepare         - Set up for building external modules'
1192         @echo  '  tags/TAGS       - Generate tags file for editors'
1193         @echo  '  cscope          - Generate cscope index'
1194         @echo  '  kernelrelease   - Output the release version string'
1195         @echo  '  kernelversion   - Output the version stored in Makefile'
1196         @if [ -r $(srctree)/include/asm-$(SRCARCH)/Kbuild ]; then \
1197          echo  '  headers_install - Install sanitised kernel headers to INSTALL_HDR_PATH'; \
1198          echo  '                    (default: $(INSTALL_HDR_PATH))'; \
1199          fi
1200         @echo  ''
1201         @echo  'Static analysers'
1202         @echo  '  checkstack      - Generate a list of stack hogs'
1203         @echo  '  namespacecheck  - Name space analysis on compiled kernel'
1204         @echo  '  versioncheck    - Sanity check on version.h usage'
1205         @echo  '  includecheck    - Check for duplicate included header files'
1206         @echo  '  export_report   - List the usages of all exported symbols'
1207         @if [ -r $(srctree)/include/asm-$(SRCARCH)/Kbuild ]; then \
1208          echo  '  headers_check   - Sanity check on exported headers'; \
1209          fi
1210         @echo  ''
1211         @echo  'Kernel packaging:'
1212         @$(MAKE) $(build)=$(package-dir) help
1213         @echo  ''
1214         @echo  'Documentation targets:'
1215         @$(MAKE) -f $(srctree)/Documentation/DocBook/Makefile dochelp
1216         @echo  ''
1217         @echo  'Architecture specific targets ($(ARCH)):'
1218         @$(if $(archhelp),$(archhelp),\
1219                 echo '  No architecture specific help defined for $(ARCH)')
1220         @echo  ''
1221         @$(if $(boards), \
1222                 $(foreach b, $(boards), \
1223                 printf "  %-24s - Build for %s\\n" $(b) $(subst _defconfig,,$(b));) \
1224                 echo '')
1225
1226         @echo  '  make V=0|1 [targets] 0 => quiet build (default), 1 => verbose build'
1227         @echo  '  make V=2   [targets] 2 => give reason for rebuild of target'
1228         @echo  '  make O=dir [targets] Locate all output files in "dir", including .config'
1229         @echo  '  make C=1   [targets] Check all c source with $$CHECK (sparse by default)'
1230         @echo  '  make C=2   [targets] Force check of all c source with $$CHECK'
1231         @echo  ''
1232         @echo  'Execute "make" or "make all" to build all targets marked with [*] '
1233         @echo  'For further info see the ./README file'
1234
1235
1236 # Documentation targets
1237 # ---------------------------------------------------------------------------
1238 %docs: scripts_basic FORCE
1239         $(Q)$(MAKE) $(build)=Documentation/DocBook $@
1240
1241 else # KBUILD_EXTMOD
1242
1243 ###
1244 # External module support.
1245 # When building external modules the kernel used as basis is considered
1246 # read-only, and no consistency checks are made and the make
1247 # system is not used on the basis kernel. If updates are required
1248 # in the basis kernel ordinary make commands (without M=...) must
1249 # be used.
1250 #
1251 # The following are the only valid targets when building external
1252 # modules.
1253 # make M=dir clean     Delete all automatically generated files
1254 # make M=dir modules   Make all modules in specified dir
1255 # make M=dir           Same as 'make M=dir modules'
1256 # make M=dir modules_install
1257 #                      Install the modules built in the module directory
1258 #                      Assumes install directory is already created
1259
1260 # We are always building modules
1261 KBUILD_MODULES := 1
1262 PHONY += crmodverdir
1263 crmodverdir:
1264         $(cmd_crmodverdir)
1265
1266 PHONY += $(objtree)/Module.symvers
1267 $(objtree)/Module.symvers:
1268         @test -e $(objtree)/Module.symvers || ( \
1269         echo; \
1270         echo "  WARNING: Symbol version dump $(objtree)/Module.symvers"; \
1271         echo "           is missing; modules will have no dependencies and modversions."; \
1272         echo )
1273
1274 module-dirs := $(addprefix _module_,$(KBUILD_EXTMOD))
1275 PHONY += $(module-dirs) modules
1276 $(module-dirs): crmodverdir $(objtree)/Module.symvers
1277         $(Q)$(MAKE) $(build)=$(patsubst _module_%,%,$@)
1278
1279 modules: $(module-dirs)
1280         @echo '  Building modules, stage 2.';
1281         $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
1282
1283 PHONY += modules_install
1284 modules_install: _emodinst_ _emodinst_post
1285
1286 install-dir := $(if $(INSTALL_MOD_DIR),$(INSTALL_MOD_DIR),extra)
1287 PHONY += _emodinst_
1288 _emodinst_:
1289         $(Q)mkdir -p $(MODLIB)/$(install-dir)
1290         $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst
1291
1292 PHONY += _emodinst_post
1293 _emodinst_post: _emodinst_
1294         $(call cmd,depmod)
1295
1296 clean-dirs := $(addprefix _clean_,$(KBUILD_EXTMOD))
1297
1298 PHONY += $(clean-dirs) clean
1299 $(clean-dirs):
1300         $(Q)$(MAKE) $(clean)=$(patsubst _clean_%,%,$@)
1301
1302 clean:  rm-dirs := $(MODVERDIR)
1303 clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers
1304 clean: $(clean-dirs)
1305         $(call cmd,rmdirs)
1306         $(call cmd,rmfiles)
1307         @find $(KBUILD_EXTMOD) $(RCS_FIND_IGNORE) \
1308                 \( -name '*.[oas]' -o -name '*.ko' -o -name '.*.cmd' \
1309                 -o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \) \
1310                 -type f -print | xargs rm -f
1311
1312 help:
1313         @echo  '  Building external modules.'
1314         @echo  '  Syntax: make -C path/to/kernel/src M=$$PWD target'
1315         @echo  ''
1316         @echo  '  modules         - default target, build the module(s)'
1317         @echo  '  modules_install - install the module'
1318         @echo  '  clean           - remove generated files in module directory only'
1319         @echo  ''
1320
1321 # Dummies...
1322 PHONY += prepare scripts
1323 prepare: ;
1324 scripts: ;
1325 endif # KBUILD_EXTMOD
1326
1327 # Generate tags for editors
1328 # ---------------------------------------------------------------------------
1329
1330 #We want __srctree to totally vanish out when KBUILD_OUTPUT is not set
1331 #(which is the most common case IMHO) to avoid unneeded clutter in the big tags file.
1332 #Adding $(srctree) adds about 20M on i386 to the size of the output file!
1333
1334 ifeq ($(src),$(obj))
1335 __srctree =
1336 else
1337 __srctree = $(srctree)/
1338 endif
1339
1340 ifeq ($(ALLSOURCE_ARCHS),)
1341 ifeq ($(ARCH),um)
1342 ALLINCLUDE_ARCHS := $(ARCH) $(SUBARCH)
1343 else
1344 ALLINCLUDE_ARCHS := $(SRCARCH)
1345 endif
1346 else
1347 #Allow user to specify only ALLSOURCE_PATHS on the command line, keeping existing behaviour.
1348 ALLINCLUDE_ARCHS := $(ALLSOURCE_ARCHS)
1349 endif
1350
1351 ALLSOURCE_ARCHS := $(SRCARCH)
1352
1353 define find-sources
1354         ( for arch in $(ALLSOURCE_ARCHS) ; do \
1355                find $(__srctree)arch/$${arch} $(RCS_FIND_IGNORE) \
1356                     -name $1 -print; \
1357           done ; \
1358           find $(__srctree)security/selinux/include $(RCS_FIND_IGNORE) \
1359                -name $1 -print; \
1360           find $(__srctree)include $(RCS_FIND_IGNORE) \
1361                \( -name config -o -name 'asm-*' \) -prune \
1362                -o -name $1 -print; \
1363           for arch in $(ALLINCLUDE_ARCHS) ; do \
1364                find $(__srctree)include/asm-$${arch} $(RCS_FIND_IGNORE) \
1365                     -name $1 -print; \
1366           done ; \
1367           find $(__srctree)include/asm-generic $(RCS_FIND_IGNORE) \
1368                -name $1 -print; \
1369           find $(__srctree) $(RCS_FIND_IGNORE) \
1370                \( -name include -o -name arch -o -name '.tmp_*' \) -prune -o \
1371                -name $1 -print; \
1372           )
1373 endef
1374
1375 define all-sources
1376         $(call find-sources,'*.[chS]')
1377 endef
1378 define all-kconfigs
1379         $(call find-sources,'Kconfig*')
1380 endef
1381 define all-defconfigs
1382         $(call find-sources,'defconfig')
1383 endef
1384
1385 define xtags
1386         if $1 --version 2>&1 | grep -iq exuberant; then \
1387             $(all-sources) | xargs $1 -a \
1388                 -I __initdata,__exitdata,__acquires,__releases \
1389                 -I __read_mostly,____cacheline_aligned,____cacheline_aligned_in_smp,____cacheline_internodealigned_in_smp \
1390                 -I EXPORT_SYMBOL,EXPORT_SYMBOL_GPL \
1391                 --extra=+f --c-kinds=+px \
1392                 --regex-asm='/^ENTRY\(([^)]*)\).*/\1/'; \
1393             $(all-kconfigs) | xargs $1 -a \
1394                 --langdef=kconfig \
1395                 --language-force=kconfig \
1396                 --regex-kconfig='/^[[:blank:]]*config[[:blank:]]+([[:alnum:]_]+)/\1/'; \
1397             $(all-defconfigs) | xargs -r $1 -a \
1398                 --langdef=dotconfig \
1399                 --language-force=dotconfig \
1400                 --regex-dotconfig='/^#?[[:blank:]]*(CONFIG_[[:alnum:]_]+)/\1/'; \
1401         elif $1 --version 2>&1 | grep -iq emacs; then \
1402             $(all-sources) | xargs $1 -a; \
1403             $(all-kconfigs) | xargs $1 -a \
1404                 --regex='/^[ \t]*config[ \t]+\([a-zA-Z0-9_]+\)/\1/'; \
1405             $(all-defconfigs) | xargs -r $1 -a \
1406                 --regex='/^#?[ \t]?\(CONFIG_[a-zA-Z0-9_]+\)/\1/'; \
1407         else \
1408             $(all-sources) | xargs $1 -a; \
1409         fi
1410 endef
1411
1412 quiet_cmd_cscope-file = FILELST cscope.files
1413       cmd_cscope-file = (echo \-k; echo \-q; $(all-sources)) > cscope.files
1414
1415 quiet_cmd_cscope = MAKE    cscope.out
1416       cmd_cscope = cscope -b
1417
1418 cscope: FORCE
1419         $(call cmd,cscope-file)
1420         $(call cmd,cscope)
1421
1422 quiet_cmd_TAGS = MAKE   $@
1423 define cmd_TAGS
1424         rm -f $@; \
1425         $(call xtags,etags)
1426 endef
1427
1428 TAGS: FORCE
1429         $(call cmd,TAGS)
1430
1431 quiet_cmd_tags = MAKE   $@
1432 define cmd_tags
1433         rm -f $@; \
1434         $(call xtags,ctags)
1435 endef
1436
1437 tags: FORCE
1438         $(call cmd,tags)
1439
1440
1441 # Scripts to check various things for consistency
1442 # ---------------------------------------------------------------------------
1443
1444 includecheck:
1445         find * $(RCS_FIND_IGNORE) \
1446                 -name '*.[hcS]' -type f -print | sort \
1447                 | xargs $(PERL) -w $(srctree)/scripts/checkincludes.pl
1448
1449 versioncheck:
1450         find * $(RCS_FIND_IGNORE) \
1451                 -name '*.[hcS]' -type f -print | sort \
1452                 | xargs $(PERL) -w $(srctree)/scripts/checkversion.pl
1453
1454 namespacecheck:
1455         $(PERL) $(srctree)/scripts/namespace.pl
1456
1457 export_report:
1458         $(PERL) $(srctree)/scripts/export_report.pl
1459
1460 endif #ifeq ($(config-targets),1)
1461 endif #ifeq ($(mixed-targets),1)
1462
1463 PHONY += checkstack kernelrelease kernelversion
1464
1465 # UML needs a little special treatment here.  It wants to use the host
1466 # toolchain, so needs $(SUBARCH) passed to checkstack.pl.  Everyone
1467 # else wants $(ARCH), including people doing cross-builds, which means
1468 # that $(SUBARCH) doesn't work here.
1469 ifeq ($(ARCH), um)
1470 CHECKSTACK_ARCH := $(SUBARCH)
1471 else
1472 CHECKSTACK_ARCH := $(ARCH)
1473 endif
1474 checkstack:
1475         $(OBJDUMP) -d vmlinux $$(find . -name '*.ko') | \
1476         $(PERL) $(src)/scripts/checkstack.pl $(CHECKSTACK_ARCH)
1477
1478 kernelrelease:
1479         $(if $(wildcard include/config/kernel.release), $(Q)echo $(KERNELRELEASE), \
1480         $(error kernelrelease not valid - run 'make prepare' to update it))
1481 kernelversion:
1482         @echo $(KERNELVERSION)
1483
1484 # Single targets
1485 # ---------------------------------------------------------------------------
1486 # Single targets are compatible with:
1487 # - build with mixed source and output
1488 # - build with separate output dir 'make O=...'
1489 # - external modules
1490 #
1491 #  target-dir => where to store outputfile
1492 #  build-dir  => directory in kernel source tree to use
1493
1494 ifeq ($(KBUILD_EXTMOD),)
1495         build-dir  = $(patsubst %/,%,$(dir $@))
1496         target-dir = $(dir $@)
1497 else
1498         zap-slash=$(filter-out .,$(patsubst %/,%,$(dir $@)))
1499         build-dir  = $(KBUILD_EXTMOD)$(if $(zap-slash),/$(zap-slash))
1500         target-dir = $(if $(KBUILD_EXTMOD),$(dir $<),$(dir $@))
1501 endif
1502
1503 %.s: %.c prepare scripts FORCE
1504         $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
1505 %.i: %.c prepare scripts FORCE
1506         $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
1507 %.o: %.c prepare scripts FORCE
1508         $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
1509 %.lst: %.c prepare scripts FORCE
1510         $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
1511 %.s: %.S prepare scripts FORCE
1512         $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
1513 %.o: %.S prepare scripts FORCE
1514         $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
1515 %.symtypes: %.c prepare scripts FORCE
1516         $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
1517
1518 # Modules
1519 / %/: prepare scripts FORCE
1520         $(cmd_crmodverdir)
1521         $(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
1522         $(build)=$(build-dir)
1523 %.ko: prepare scripts FORCE
1524         $(cmd_crmodverdir)
1525         $(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1)   \
1526         $(build)=$(build-dir) $(@:.ko=.o)
1527         $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
1528
1529 # FIXME Should go into a make.lib or something
1530 # ===========================================================================
1531
1532 quiet_cmd_rmdirs = $(if $(wildcard $(rm-dirs)),CLEAN   $(wildcard $(rm-dirs)))
1533       cmd_rmdirs = rm -rf $(rm-dirs)
1534
1535 quiet_cmd_rmfiles = $(if $(wildcard $(rm-files)),CLEAN   $(wildcard $(rm-files)))
1536       cmd_rmfiles = rm -f $(rm-files)
1537
1538 # Run depmod only is we have System.map and depmod is executable
1539 # and we build for the host arch
1540 quiet_cmd_depmod = DEPMOD  $(KERNELRELEASE)
1541       cmd_depmod = \
1542         if [ -r System.map -a -x $(DEPMOD) ]; then                              \
1543                 $(DEPMOD) -ae -F System.map                                     \
1544                 $(if $(strip $(INSTALL_MOD_PATH)), -b $(INSTALL_MOD_PATH) -r)   \
1545                 $(KERNELRELEASE);                                               \
1546         fi
1547
1548 # Create temporary dir for module support files
1549 # clean it up only when building all modules
1550 cmd_crmodverdir = $(Q)mkdir -p $(MODVERDIR) \
1551                   $(if $(KBUILD_MODULES),; rm -f $(MODVERDIR)/*)
1552
1553 a_flags = -Wp,-MD,$(depfile) $(KBUILD_AFLAGS) $(AFLAGS_KERNEL) \
1554           $(NOSTDINC_FLAGS) $(KBUILD_CPPFLAGS) \
1555           $(modkern_aflags) $(EXTRA_AFLAGS) $(AFLAGS_$(basetarget).o)
1556
1557 quiet_cmd_as_o_S = AS      $@
1558 cmd_as_o_S       = $(CC) $(a_flags) -c -o $@ $<
1559
1560 # read all saved command lines
1561
1562 targets := $(wildcard $(sort $(targets)))
1563 cmd_files := $(wildcard .*.cmd $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))
1564
1565 ifneq ($(cmd_files),)
1566   $(cmd_files): ;       # Do not try to update included dependency files
1567   include $(cmd_files)
1568 endif
1569
1570 # Shorthand for $(Q)$(MAKE) -f scripts/Makefile.clean obj=dir
1571 # Usage:
1572 # $(Q)$(MAKE) $(clean)=dir
1573 clean := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.clean obj
1574
1575 endif   # skip-makefile
1576
1577 PHONY += FORCE
1578 FORCE:
1579
1580 # Declare the contents of the .PHONY variable as phony.  We keep that
1581 # information in a variable se we can use it in if_changed and friends.
1582 .PHONY: $(PHONY)