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   1# SPDX-License-Identifier: GPL-2.0
   2VERSION = 6
   3PATCHLEVEL = 17
   4SUBLEVEL = 0
   5EXTRAVERSION =
   6NAME = Baby Opossum Posse
   7
   8# *DOCUMENTATION*
   9# To see a list of typical targets execute "make help"
  10# More info can be located in ./README
  11# Comments in this file are targeted only to the developer, do not
  12# expect to learn how to build the kernel reading this file.
  13
  14ifeq ($(filter output-sync,$(.FEATURES)),)
  15$(error GNU Make >= 4.0 is required. Your Make version is $(MAKE_VERSION))
  16endif
  17
  18$(if $(filter __%, $(MAKECMDGOALS)), \
  19        $(error targets prefixed with '__' are only for internal use))
  20
  21# That's our default target when none is given on the command line
  22PHONY := __all
  23__all:
  24
  25# We are using a recursive build, so we need to do a little thinking
  26# to get the ordering right.
  27#
  28# Most importantly: sub-Makefiles should only ever modify files in
  29# their own directory. If in some directory we have a dependency on
  30# a file in another dir (which doesn't happen often, but it's often
  31# unavoidable when linking the built-in.a targets which finally
  32# turn into vmlinux), we will call a sub make in that other dir, and
  33# after that we are sure that everything which is in that other dir
  34# is now up to date.
  35#
  36# The only cases where we need to modify files which have global
  37# effects are thus separated out and done before the recursive
  38# descending is started. They are now explicitly listed as the
  39# prepare rule.
  40
  41this-makefile := $(lastword $(MAKEFILE_LIST))
  42abs_srctree := $(realpath $(dir $(this-makefile)))
  43abs_output := $(CURDIR)
  44
  45ifneq ($(sub_make_done),1)
  46
  47# Do not use make's built-in rules and variables
  48# (this increases performance and avoids hard-to-debug behaviour)
  49MAKEFLAGS += -rR
  50
  51# Avoid funny character set dependencies
  52unexport LC_ALL
  53LC_COLLATE=C
  54LC_NUMERIC=C
  55export LC_COLLATE LC_NUMERIC
  56
  57# Avoid interference with shell env settings
  58unexport GREP_OPTIONS
  59
  60# Beautify output
  61# ---------------------------------------------------------------------------
  62#
  63# Most of build commands in Kbuild start with "cmd_". You can optionally define
  64# "quiet_cmd_*". If defined, the short log is printed. Otherwise, no log from
  65# that command is printed by default.
  66#
  67# e.g.)
  68#    quiet_cmd_depmod = DEPMOD  $(MODLIB)
  69#          cmd_depmod = $(srctree)/scripts/depmod.sh $(DEPMOD) $(KERNELRELEASE)
  70#
  71# A simple variant is to prefix commands with $(Q) - that's useful
  72# for commands that shall be hidden in non-verbose mode.
  73#
  74#    $(Q)$(MAKE) $(build)=scripts/basic
  75#
  76# If KBUILD_VERBOSE contains 1, the whole command is echoed.
  77# If KBUILD_VERBOSE contains 2, the reason for rebuilding is printed.
  78#
  79# To put more focus on warnings, be less verbose as default
  80# Use 'make V=1' to see the full commands
  81
  82ifeq ("$(origin V)", "command line")
  83  KBUILD_VERBOSE = $(V)
  84endif
  85
  86quiet = quiet_
  87Q = @
  88
  89ifneq ($(findstring 1, $(KBUILD_VERBOSE)),)
  90  quiet =
  91  Q =
  92endif
  93
  94# If the user is running make -s (silent mode), suppress echoing of
  95# commands
  96ifneq ($(findstring s,$(firstword -$(MAKEFLAGS))),)
  97quiet=silent_
  98override KBUILD_VERBOSE :=
  99endif
 100
 101export quiet Q KBUILD_VERBOSE
 102
 103# Call a source code checker (by default, "sparse") as part of the
 104# C compilation.
 105#
 106# Use 'make C=1' to enable checking of only re-compiled files.
 107# Use 'make C=2' to enable checking of *all* source files, regardless
 108# of whether they are re-compiled or not.
 109#
 110# See the file "Documentation/dev-tools/sparse.rst" for more details,
 111# including where to get the "sparse" utility.
 112
 113ifeq ("$(origin C)", "command line")
 114  KBUILD_CHECKSRC = $(C)
 115endif
 116ifndef KBUILD_CHECKSRC
 117  KBUILD_CHECKSRC = 0
 118endif
 119
 120export KBUILD_CHECKSRC
 121
 122# Enable "clippy" (a linter) as part of the Rust compilation.
 123#
 124# Use 'make CLIPPY=1' to enable it.
 125ifeq ("$(origin CLIPPY)", "command line")
 126  KBUILD_CLIPPY := $(CLIPPY)
 127endif
 128
 129export KBUILD_CLIPPY
 130
 131# Use make M=dir or set the environment variable KBUILD_EXTMOD to specify the
 132# directory of external module to build. Setting M= takes precedence.
 133ifeq ("$(origin M)", "command line")
 134  KBUILD_EXTMOD := $(M)
 135endif
 136
 137ifeq ("$(origin MO)", "command line")
 138  KBUILD_EXTMOD_OUTPUT := $(MO)
 139endif
 140
 141$(if $(word 2, $(KBUILD_EXTMOD)), \
 142        $(error building multiple external modules is not supported))
 143
 144$(foreach x, % :, $(if $(findstring $x, $(KBUILD_EXTMOD)), \
 145        $(error module directory path cannot contain '$x')))
 146
 147# Remove trailing slashes
 148ifneq ($(filter %/, $(KBUILD_EXTMOD)),)
 149KBUILD_EXTMOD := $(shell dirname $(KBUILD_EXTMOD).)
 150endif
 151
 152export KBUILD_EXTMOD
 153
 154ifeq ("$(origin W)", "command line")
 155  KBUILD_EXTRA_WARN := $(W)
 156endif
 157
 158export KBUILD_EXTRA_WARN
 159
 160# Kbuild will save output files in the current working directory.
 161# This does not need to match to the root of the kernel source tree.
 162#
 163# For example, you can do this:
 164#
 165#  cd /dir/to/store/output/files; make -f /dir/to/kernel/source/Makefile
 166#
 167# If you want to save output files in a different location, there are
 168# two syntaxes to specify it.
 169#
 170# 1) O=
 171# Use "make O=dir/to/store/output/files/"
 172#
 173# 2) Set KBUILD_OUTPUT
 174# Set the environment variable KBUILD_OUTPUT to point to the output directory.
 175# export KBUILD_OUTPUT=dir/to/store/output/files/; make
 176#
 177# The O= assignment takes precedence over the KBUILD_OUTPUT environment
 178# variable.
 179
 180ifeq ("$(origin O)", "command line")
 181  KBUILD_OUTPUT := $(O)
 182endif
 183
 184ifdef KBUILD_EXTMOD
 185    ifdef KBUILD_OUTPUT
 186        objtree := $(realpath $(KBUILD_OUTPUT))
 187        $(if $(objtree),,$(error specified kernel directory "$(KBUILD_OUTPUT)" does not exist))
 188    else
 189        objtree := $(abs_srctree)
 190    endif
 191    # If Make is invoked from the kernel directory (either kernel
 192    # source directory or kernel build directory), external modules
 193    # are built in $(KBUILD_EXTMOD) for backward compatibility,
 194    # otherwise, built in the current directory.
 195    output := $(or $(KBUILD_EXTMOD_OUTPUT),$(if $(filter $(CURDIR),$(objtree) $(abs_srctree)),$(KBUILD_EXTMOD)))
 196    # KBUILD_EXTMOD might be a relative path. Remember its absolute path before
 197    # Make changes the working directory.
 198    srcroot := $(realpath $(KBUILD_EXTMOD))
 199    $(if $(srcroot),,$(error specified external module directory "$(KBUILD_EXTMOD)" does not exist))
 200else
 201    objtree := .
 202    output := $(KBUILD_OUTPUT)
 203endif
 204
 205export objtree srcroot
 206
 207# Do we want to change the working directory?
 208ifneq ($(output),)
 209# $(realpath ...) gets empty if the path does not exist. Run 'mkdir -p' first.
 210$(shell mkdir -p "$(output)")
 211# $(realpath ...) resolves symlinks
 212abs_output := $(realpath $(output))
 213$(if $(abs_output),,$(error failed to create output directory "$(output)"))
 214endif
 215
 216ifneq ($(words $(subst :, ,$(abs_srctree))), 1)
 217$(error source directory cannot contain spaces or colons)
 218endif
 219
 220export sub_make_done := 1
 221
 222endif # sub_make_done
 223
 224ifeq ($(abs_output),$(CURDIR))
 225# Suppress "Entering directory ..." if we are at the final work directory.
 226no-print-directory := --no-print-directory
 227else
 228# Recursion to show "Entering directory ..."
 229need-sub-make := 1
 230endif
 231
 232ifeq ($(filter --no-print-directory, $(MAKEFLAGS)),)
 233# If --no-print-directory is unset, recurse once again to set it.
 234# You may end up recursing into __sub-make twice. This is needed due to the
 235# behavior change in GNU Make 4.4.1.
 236need-sub-make := 1
 237endif
 238
 239ifeq ($(need-sub-make),1)
 240
 241PHONY += $(MAKECMDGOALS) __sub-make
 242
 243$(filter-out $(this-makefile), $(MAKECMDGOALS)) __all: __sub-make
 244        @:
 245
 246# Invoke a second make in the output directory, passing relevant variables
 247__sub-make:
 248        $(Q)$(MAKE) $(no-print-directory) -C $(abs_output) \
 249        -f $(abs_srctree)/Makefile $(MAKECMDGOALS)
 250
 251else # need-sub-make
 252
 253# We process the rest of the Makefile if this is the final invocation of make
 254
 255ifndef KBUILD_EXTMOD
 256srcroot := $(abs_srctree)
 257endif
 258
 259ifeq ($(srcroot),$(CURDIR))
 260building_out_of_srctree :=
 261else
 262export building_out_of_srctree := 1
 263endif
 264
 265ifdef KBUILD_ABS_SRCTREE
 266    # Do nothing. Use the absolute path.
 267else ifeq ($(srcroot),$(CURDIR))
 268    # Building in the source.
 269    srcroot := .
 270else ifeq ($(srcroot)/,$(dir $(CURDIR)))
 271    # Building in a subdirectory of the source.
 272    srcroot := ..
 273endif
 274
 275export srctree := $(if $(KBUILD_EXTMOD),$(abs_srctree),$(srcroot))
 276
 277ifdef building_out_of_srctree
 278export VPATH := $(srcroot)
 279else
 280VPATH :=
 281endif
 282
 283# To make sure we do not include .config for any of the *config targets
 284# catch them early, and hand them over to scripts/kconfig/Makefile
 285# It is allowed to specify more targets when calling make, including
 286# mixing *config targets and build targets.
 287# For example 'make oldconfig all'.
 288# Detect when mixed targets is specified, and make a second invocation
 289# of make so .config is not included in this case either (for *config).
 290
 291version_h := include/generated/uapi/linux/version.h
 292
 293clean-targets := %clean mrproper cleandocs
 294no-dot-config-targets := $(clean-targets) \
 295                         cscope gtags TAGS tags help% %docs check% coccicheck \
 296                         $(version_h) headers headers_% archheaders archscripts \
 297                         %asm-generic kernelversion %src-pkg dt_binding_check \
 298                         outputmakefile rustavailable rustfmt rustfmtcheck
 299no-sync-config-targets := $(no-dot-config-targets) %install modules_sign kernelrelease \
 300                          image_name
 301single-targets := %.a %.i %.ko %.lds %.ll %.lst %.mod %.o %.rsi %.s %/
 302
 303config-build    :=
 304mixed-build     :=
 305need-config     := 1
 306may-sync-config := 1
 307single-build    :=
 308
 309ifneq ($(filter $(no-dot-config-targets), $(MAKECMDGOALS)),)
 310    ifeq ($(filter-out $(no-dot-config-targets), $(MAKECMDGOALS)),)
 311        need-config :=
 312    endif
 313endif
 314
 315ifneq ($(filter $(no-sync-config-targets), $(MAKECMDGOALS)),)
 316    ifeq ($(filter-out $(no-sync-config-targets), $(MAKECMDGOALS)),)
 317        may-sync-config :=
 318    endif
 319endif
 320
 321need-compiler := $(may-sync-config)
 322
 323ifneq ($(KBUILD_EXTMOD),)
 324    may-sync-config :=
 325endif
 326
 327ifeq ($(KBUILD_EXTMOD),)
 328    ifneq ($(filter %config,$(MAKECMDGOALS)),)
 329        config-build := 1
 330        ifneq ($(words $(MAKECMDGOALS)),1)
 331            mixed-build := 1
 332        endif
 333    endif
 334endif
 335
 336# We cannot build single targets and the others at the same time
 337ifneq ($(filter $(single-targets), $(MAKECMDGOALS)),)
 338    single-build := 1
 339    ifneq ($(filter-out $(single-targets), $(MAKECMDGOALS)),)
 340        mixed-build := 1
 341    endif
 342endif
 343
 344# For "make -j clean all", "make -j mrproper defconfig all", etc.
 345ifneq ($(filter $(clean-targets),$(MAKECMDGOALS)),)
 346    ifneq ($(filter-out $(clean-targets),$(MAKECMDGOALS)),)
 347        mixed-build := 1
 348    endif
 349endif
 350
 351# install and modules_install need also be processed one by one
 352ifneq ($(filter install,$(MAKECMDGOALS)),)
 353    ifneq ($(filter modules_install,$(MAKECMDGOALS)),)
 354        mixed-build := 1
 355    endif
 356endif
 357
 358ifdef mixed-build
 359# ===========================================================================
 360# We're called with mixed targets (*config and build targets).
 361# Handle them one by one.
 362
 363PHONY += $(MAKECMDGOALS) __build_one_by_one
 364
 365$(MAKECMDGOALS): __build_one_by_one
 366        @:
 367
 368__build_one_by_one:
 369        $(Q)set -e; \
 370        for i in $(MAKECMDGOALS); do \
 371                $(MAKE) -f $(srctree)/Makefile $$i; \
 372        done
 373
 374else # !mixed-build
 375
 376include $(srctree)/scripts/Kbuild.include
 377
 378# Read KERNELRELEASE from include/config/kernel.release (if it exists)
 379KERNELRELEASE = $(call read-file, $(objtree)/include/config/kernel.release)
 380KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION)
 381export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION
 382
 383include $(srctree)/scripts/subarch.include
 384
 385# Cross compiling and selecting different set of gcc/bin-utils
 386# ---------------------------------------------------------------------------
 387#
 388# When performing cross compilation for other architectures ARCH shall be set
 389# to the target architecture. (See arch/* for the possibilities).
 390# ARCH can be set during invocation of make:
 391# make ARCH=arm64
 392# Another way is to have ARCH set in the environment.
 393# The default ARCH is the host where make is executed.
 394
 395# CROSS_COMPILE specify the prefix used for all executables used
 396# during compilation. Only gcc and related bin-utils executables
 397# are prefixed with $(CROSS_COMPILE).
 398# CROSS_COMPILE can be set on the command line
 399# make CROSS_COMPILE=aarch64-linux-gnu-
 400# Alternatively CROSS_COMPILE can be set in the environment.
 401# Default value for CROSS_COMPILE is not to prefix executables
 402# Note: Some architectures assign CROSS_COMPILE in their arch/*/Makefile
 403ARCH            ?= $(SUBARCH)
 404
 405# Architecture as present in compile.h
 406UTS_MACHINE     := $(ARCH)
 407SRCARCH         := $(ARCH)
 408
 409# Additional ARCH settings for x86
 410ifeq ($(ARCH),i386)
 411        SRCARCH := x86
 412endif
 413ifeq ($(ARCH),x86_64)
 414        SRCARCH := x86
 415endif
 416
 417# Additional ARCH settings for sparc
 418ifeq ($(ARCH),sparc32)
 419       SRCARCH := sparc
 420endif
 421ifeq ($(ARCH),sparc64)
 422       SRCARCH := sparc
 423endif
 424
 425# Additional ARCH settings for parisc
 426ifeq ($(ARCH),parisc64)
 427       SRCARCH := parisc
 428endif
 429
 430export cross_compiling :=
 431ifneq ($(SRCARCH),$(SUBARCH))
 432cross_compiling := 1
 433endif
 434
 435KCONFIG_CONFIG  ?= .config
 436export KCONFIG_CONFIG
 437
 438# SHELL used by kbuild
 439CONFIG_SHELL := sh
 440
 441HOST_LFS_CFLAGS := $(shell getconf LFS_CFLAGS 2>/dev/null)
 442HOST_LFS_LDFLAGS := $(shell getconf LFS_LDFLAGS 2>/dev/null)
 443HOST_LFS_LIBS := $(shell getconf LFS_LIBS 2>/dev/null)
 444
 445ifneq ($(LLVM),)
 446ifneq ($(filter %/,$(LLVM)),)
 447LLVM_PREFIX := $(LLVM)
 448else ifneq ($(filter -%,$(LLVM)),)
 449LLVM_SUFFIX := $(LLVM)
 450endif
 451
 452HOSTCC  = $(LLVM_PREFIX)clang$(LLVM_SUFFIX)
 453HOSTCXX = $(LLVM_PREFIX)clang++$(LLVM_SUFFIX)
 454else
 455HOSTCC  = gcc
 456HOSTCXX = g++
 457endif
 458HOSTRUSTC = rustc
 459HOSTPKG_CONFIG  = pkg-config
 460
 461# the KERNELDOC macro needs to be exported, as scripts/Makefile.build
 462# has a logic to call it
 463KERNELDOC       = $(srctree)/scripts/kernel-doc.py
 464export KERNELDOC
 465
 466KBUILD_USERHOSTCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
 467                         -O2 -fomit-frame-pointer -std=gnu11
 468KBUILD_USERCFLAGS  := $(KBUILD_USERHOSTCFLAGS) $(USERCFLAGS)
 469KBUILD_USERLDFLAGS := $(USERLDFLAGS)
 470
 471# These flags apply to all Rust code in the tree, including the kernel and
 472# host programs.
 473export rust_common_flags := --edition=2021 \
 474                            -Zbinary_dep_depinfo=y \
 475                            -Astable_features \
 476                            -Dnon_ascii_idents \
 477                            -Dunsafe_op_in_unsafe_fn \
 478                            -Wmissing_docs \
 479                            -Wrust_2018_idioms \
 480                            -Wunreachable_pub \
 481                            -Wclippy::all \
 482                            -Wclippy::as_ptr_cast_mut \
 483                            -Wclippy::as_underscore \
 484                            -Wclippy::cast_lossless \
 485                            -Wclippy::ignored_unit_patterns \
 486                            -Wclippy::mut_mut \
 487                            -Wclippy::needless_bitwise_bool \
 488                            -Aclippy::needless_lifetimes \
 489                            -Wclippy::no_mangle_with_rust_abi \
 490                            -Wclippy::ptr_as_ptr \
 491                            -Wclippy::ptr_cast_constness \
 492                            -Wclippy::ref_as_ptr \
 493                            -Wclippy::undocumented_unsafe_blocks \
 494                            -Wclippy::unnecessary_safety_comment \
 495                            -Wclippy::unnecessary_safety_doc \
 496                            -Wrustdoc::missing_crate_level_docs \
 497                            -Wrustdoc::unescaped_backticks
 498
 499KBUILD_HOSTCFLAGS   := $(KBUILD_USERHOSTCFLAGS) $(HOST_LFS_CFLAGS) \
 500                       $(HOSTCFLAGS) -I $(srctree)/scripts/include
 501KBUILD_HOSTCXXFLAGS := -Wall -O2 $(HOST_LFS_CFLAGS) $(HOSTCXXFLAGS) \
 502                       -I $(srctree)/scripts/include
 503KBUILD_HOSTRUSTFLAGS := $(rust_common_flags) -O -Cstrip=debuginfo \
 504                        -Zallow-features= $(HOSTRUSTFLAGS)
 505KBUILD_HOSTLDFLAGS  := $(HOST_LFS_LDFLAGS) $(HOSTLDFLAGS)
 506KBUILD_HOSTLDLIBS   := $(HOST_LFS_LIBS) $(HOSTLDLIBS)
 507KBUILD_PROCMACROLDFLAGS := $(or $(PROCMACROLDFLAGS),$(KBUILD_HOSTLDFLAGS))
 508
 509# Make variables (CC, etc...)
 510CPP             = $(CC) -E
 511ifneq ($(LLVM),)
 512CC              = $(LLVM_PREFIX)clang$(LLVM_SUFFIX)
 513LD              = $(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX)
 514AR              = $(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX)
 515NM              = $(LLVM_PREFIX)llvm-nm$(LLVM_SUFFIX)
 516OBJCOPY         = $(LLVM_PREFIX)llvm-objcopy$(LLVM_SUFFIX)
 517OBJDUMP         = $(LLVM_PREFIX)llvm-objdump$(LLVM_SUFFIX)
 518READELF         = $(LLVM_PREFIX)llvm-readelf$(LLVM_SUFFIX)
 519STRIP           = $(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX)
 520else
 521CC              = $(CROSS_COMPILE)gcc
 522LD              = $(CROSS_COMPILE)ld
 523AR              = $(CROSS_COMPILE)ar
 524NM              = $(CROSS_COMPILE)nm
 525OBJCOPY         = $(CROSS_COMPILE)objcopy
 526OBJDUMP         = $(CROSS_COMPILE)objdump
 527READELF         = $(CROSS_COMPILE)readelf
 528STRIP           = $(CROSS_COMPILE)strip
 529endif
 530RUSTC           = rustc
 531RUSTDOC         = rustdoc
 532RUSTFMT         = rustfmt
 533CLIPPY_DRIVER   = clippy-driver
 534BINDGEN         = bindgen
 535PAHOLE          = pahole
 536RESOLVE_BTFIDS  = $(objtree)/tools/bpf/resolve_btfids/resolve_btfids
 537LEX             = flex
 538YACC            = bison
 539AWK             = awk
 540INSTALLKERNEL  := installkernel
 541PERL            = perl
 542PYTHON3         = python3
 543CHECK           = sparse
 544BASH            = bash
 545KGZIP           = gzip
 546KBZIP2          = bzip2
 547KLZOP           = lzop
 548LZMA            = lzma
 549LZ4             = lz4
 550XZ              = xz
 551ZSTD            = zstd
 552TAR             = tar
 553
 554CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
 555                  -Wbitwise -Wno-return-void -Wno-unknown-attribute $(CF)
 556NOSTDINC_FLAGS :=
 557CFLAGS_MODULE   =
 558RUSTFLAGS_MODULE =
 559AFLAGS_MODULE   =
 560LDFLAGS_MODULE  =
 561CFLAGS_KERNEL   =
 562RUSTFLAGS_KERNEL =
 563AFLAGS_KERNEL   =
 564LDFLAGS_vmlinux =
 565
 566# Use USERINCLUDE when you must reference the UAPI directories only.
 567USERINCLUDE    := \
 568                -I$(srctree)/arch/$(SRCARCH)/include/uapi \
 569                -I$(objtree)/arch/$(SRCARCH)/include/generated/uapi \
 570                -I$(srctree)/include/uapi \
 571                -I$(objtree)/include/generated/uapi \
 572                -include $(srctree)/include/linux/compiler-version.h \
 573                -include $(srctree)/include/linux/kconfig.h
 574
 575# Use LINUXINCLUDE when you must reference the include/ directory.
 576# Needed to be compatible with the O= option
 577LINUXINCLUDE    := \
 578                -I$(srctree)/arch/$(SRCARCH)/include \
 579                -I$(objtree)/arch/$(SRCARCH)/include/generated \
 580                -I$(srctree)/include \
 581                -I$(objtree)/include \
 582                $(USERINCLUDE)
 583
 584KBUILD_AFLAGS   := -D__ASSEMBLY__ -fno-PIE
 585
 586KBUILD_CFLAGS :=
 587KBUILD_CFLAGS += -std=gnu11
 588KBUILD_CFLAGS += -fshort-wchar
 589KBUILD_CFLAGS += -funsigned-char
 590KBUILD_CFLAGS += -fno-common
 591KBUILD_CFLAGS += -fno-PIE
 592KBUILD_CFLAGS += -fno-strict-aliasing
 593
 594KBUILD_CPPFLAGS := -D__KERNEL__
 595KBUILD_RUSTFLAGS := $(rust_common_flags) \
 596                    -Cpanic=abort -Cembed-bitcode=n -Clto=n \
 597                    -Cforce-unwind-tables=n -Ccodegen-units=1 \
 598                    -Csymbol-mangling-version=v0 \
 599                    -Crelocation-model=static \
 600                    -Zfunction-sections=n \
 601                    -Wclippy::float_arithmetic
 602
 603KBUILD_AFLAGS_KERNEL :=
 604KBUILD_CFLAGS_KERNEL :=
 605KBUILD_RUSTFLAGS_KERNEL :=
 606KBUILD_AFLAGS_MODULE  := -DMODULE
 607KBUILD_CFLAGS_MODULE  := -DMODULE
 608KBUILD_RUSTFLAGS_MODULE := --cfg MODULE
 609KBUILD_LDFLAGS_MODULE :=
 610KBUILD_LDFLAGS :=
 611CLANG_FLAGS :=
 612
 613ifeq ($(KBUILD_CLIPPY),1)
 614        RUSTC_OR_CLIPPY_QUIET := CLIPPY
 615        RUSTC_OR_CLIPPY = $(CLIPPY_DRIVER)
 616else
 617        RUSTC_OR_CLIPPY_QUIET := RUSTC
 618        RUSTC_OR_CLIPPY = $(RUSTC)
 619endif
 620
 621# Allows the usage of unstable features in stable compilers.
 622export RUSTC_BOOTSTRAP := 1
 623
 624# Allows finding `.clippy.toml` in out-of-srctree builds.
 625export CLIPPY_CONF_DIR := $(srctree)
 626
 627export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC HOSTPKG_CONFIG
 628export RUSTC RUSTDOC RUSTFMT RUSTC_OR_CLIPPY_QUIET RUSTC_OR_CLIPPY BINDGEN
 629export HOSTRUSTC KBUILD_HOSTRUSTFLAGS
 630export CPP AR NM STRIP OBJCOPY OBJDUMP READELF PAHOLE RESOLVE_BTFIDS LEX YACC AWK INSTALLKERNEL
 631export PERL PYTHON3 CHECK CHECKFLAGS MAKE UTS_MACHINE HOSTCXX
 632export KGZIP KBZIP2 KLZOP LZMA LZ4 XZ ZSTD TAR
 633export KBUILD_HOSTCXXFLAGS KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS KBUILD_PROCMACROLDFLAGS LDFLAGS_MODULE
 634export KBUILD_USERCFLAGS KBUILD_USERLDFLAGS
 635
 636export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS KBUILD_LDFLAGS
 637export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
 638export KBUILD_RUSTFLAGS RUSTFLAGS_KERNEL RUSTFLAGS_MODULE
 639export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
 640export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_RUSTFLAGS_MODULE KBUILD_LDFLAGS_MODULE
 641export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL KBUILD_RUSTFLAGS_KERNEL
 642
 643# Files to ignore in find ... statements
 644
 645export RCS_FIND_IGNORE := \( -name SCCS -o -name BitKeeper -o -name .svn -o    \
 646                          -name CVS -o -name .pc -o -name .hg -o -name .git \) \
 647                          -prune -o
 648
 649# ===========================================================================
 650# Rules shared between *config targets and build targets
 651
 652# Basic helpers built in scripts/basic/
 653PHONY += scripts_basic
 654scripts_basic:
 655        $(Q)$(MAKE) $(build)=scripts/basic
 656
 657PHONY += outputmakefile
 658ifdef building_out_of_srctree
 659# Before starting out-of-tree build, make sure the source tree is clean.
 660# outputmakefile generates a Makefile in the output directory, if using a
 661# separate output directory. This allows convenient use of make in the
 662# output directory.
 663# At the same time when output Makefile generated, generate .gitignore to
 664# ignore whole output directory
 665
 666ifdef KBUILD_EXTMOD
 667print_env_for_makefile = \
 668        echo "export KBUILD_OUTPUT = $(objtree)"; \
 669        echo "export KBUILD_EXTMOD = $(realpath $(srcroot))" ; \
 670        echo "export KBUILD_EXTMOD_OUTPUT = $(CURDIR)"
 671else
 672print_env_for_makefile = \
 673        echo "export KBUILD_OUTPUT = $(CURDIR)"
 674endif
 675
 676quiet_cmd_makefile = GEN     Makefile
 677      cmd_makefile = { \
 678        echo "\# Automatically generated by $(abs_srctree)/Makefile: don't edit"; \
 679        $(print_env_for_makefile); \
 680        echo "include $(abs_srctree)/Makefile"; \
 681        } > Makefile
 682
 683outputmakefile:
 684ifeq ($(KBUILD_EXTMOD),)
 685        @if [ -f $(srctree)/.config -o \
 686                 -d $(srctree)/include/config -o \
 687                 -d $(srctree)/arch/$(SRCARCH)/include/generated ]; then \
 688                echo >&2 "***"; \
 689                echo >&2 "*** The source tree is not clean, please run 'make$(if $(findstring command line, $(origin ARCH)), ARCH=$(ARCH)) mrproper'"; \
 690                echo >&2 "*** in $(abs_srctree)";\
 691                echo >&2 "***"; \
 692                false; \
 693        fi
 694else
 695        @if [ -f $(srcroot)/modules.order ]; then \
 696                echo >&2 "***"; \
 697                echo >&2 "*** The external module source tree is not clean."; \
 698                echo >&2 "*** Please run 'make -C $(abs_srctree) M=$(realpath $(srcroot)) clean'"; \
 699                echo >&2 "***"; \
 700                false; \
 701        fi
 702endif
 703        $(Q)ln -fsn $(srcroot) source
 704        $(call cmd,makefile)
 705        $(Q)test -e .gitignore || \
 706        { echo "# this is build directory, ignore it"; echo "*"; } > .gitignore
 707endif
 708
 709# The expansion should be delayed until arch/$(SRCARCH)/Makefile is included.
 710# Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile.
 711# CC_VERSION_TEXT and RUSTC_VERSION_TEXT are referenced from Kconfig (so they
 712# need export), and from include/config/auto.conf.cmd to detect the compiler
 713# upgrade.
 714CC_VERSION_TEXT = $(subst $(pound),,$(shell LC_ALL=C $(CC) --version 2>/dev/null | head -n 1))
 715RUSTC_VERSION_TEXT = $(subst $(pound),,$(shell $(RUSTC) --version 2>/dev/null))
 716
 717ifneq ($(findstring clang,$(CC_VERSION_TEXT)),)
 718include $(srctree)/scripts/Makefile.clang
 719endif
 720
 721# Include this also for config targets because some architectures need
 722# cc-cross-prefix to determine CROSS_COMPILE.
 723ifdef need-compiler
 724include $(srctree)/scripts/Makefile.compiler
 725endif
 726
 727ifdef config-build
 728# ===========================================================================
 729# *config targets only - make sure prerequisites are updated, and descend
 730# in scripts/kconfig to make the *config target
 731
 732# Read arch-specific Makefile to set KBUILD_DEFCONFIG as needed.
 733# KBUILD_DEFCONFIG may point out an alternative default configuration
 734# used for 'make defconfig'
 735include $(srctree)/arch/$(SRCARCH)/Makefile
 736export KBUILD_DEFCONFIG KBUILD_KCONFIG CC_VERSION_TEXT RUSTC_VERSION_TEXT
 737
 738config: outputmakefile scripts_basic FORCE
 739        $(Q)$(MAKE) $(build)=scripts/kconfig $@
 740
 741%config: outputmakefile scripts_basic FORCE
 742        $(Q)$(MAKE) $(build)=scripts/kconfig $@
 743
 744else #!config-build
 745# ===========================================================================
 746# Build targets only - this includes vmlinux, arch-specific targets, clean
 747# targets and others. In general all targets except *config targets.
 748
 749# If building an external module we do not care about the all: rule
 750# but instead __all depend on modules
 751PHONY += all
 752ifeq ($(KBUILD_EXTMOD),)
 753__all: all
 754else
 755__all: modules
 756endif
 757
 758targets :=
 759
 760# Decide whether to build built-in, modular, or both.
 761# Normally, just do built-in.
 762
 763KBUILD_MODULES :=
 764KBUILD_BUILTIN := y
 765
 766# If we have only "make modules", don't compile built-in objects.
 767ifeq ($(MAKECMDGOALS),modules)
 768  KBUILD_BUILTIN :=
 769endif
 770
 771# If we have "make <whatever> modules", compile modules
 772# in addition to whatever we do anyway.
 773# Just "make" or "make all" shall build modules as well
 774
 775ifneq ($(filter all modules nsdeps compile_commands.json clang-%,$(MAKECMDGOALS)),)
 776  KBUILD_MODULES := y
 777endif
 778
 779ifeq ($(MAKECMDGOALS),)
 780  KBUILD_MODULES := y
 781endif
 782
 783export KBUILD_MODULES KBUILD_BUILTIN
 784
 785ifdef need-config
 786include $(objtree)/include/config/auto.conf
 787endif
 788
 789ifeq ($(KBUILD_EXTMOD),)
 790# Objects we will link into vmlinux / subdirs we need to visit
 791core-y          :=
 792drivers-y       :=
 793libs-y          := lib/
 794endif # KBUILD_EXTMOD
 795
 796# The all: target is the default when no target is given on the
 797# command line.
 798# This allow a user to issue only 'make' to build a kernel including modules
 799# Defaults to vmlinux, but the arch makefile usually adds further targets
 800all: vmlinux
 801
 802CFLAGS_GCOV     := -fprofile-arcs -ftest-coverage
 803ifdef CONFIG_CC_IS_GCC
 804CFLAGS_GCOV     += -fno-tree-loop-im
 805endif
 806export CFLAGS_GCOV
 807
 808# The arch Makefiles can override CC_FLAGS_FTRACE. We may also append it later.
 809ifdef CONFIG_FUNCTION_TRACER
 810  CC_FLAGS_FTRACE := -pg
 811endif
 812
 813include $(srctree)/arch/$(SRCARCH)/Makefile
 814
 815ifdef need-config
 816ifdef may-sync-config
 817# Read in dependencies to all Kconfig* files, make sure to run syncconfig if
 818# changes are detected. This should be included after arch/$(SRCARCH)/Makefile
 819# because some architectures define CROSS_COMPILE there.
 820include include/config/auto.conf.cmd
 821
 822$(KCONFIG_CONFIG):
 823        @echo >&2 '***'
 824        @echo >&2 '*** Configuration file "$@" not found!'
 825        @echo >&2 '***'
 826        @echo >&2 '*** Please run some configurator (e.g. "make oldconfig" or'
 827        @echo >&2 '*** "make menuconfig" or "make xconfig").'
 828        @echo >&2 '***'
 829        @/bin/false
 830
 831# The actual configuration files used during the build are stored in
 832# include/generated/ and include/config/. Update them if .config is newer than
 833# include/config/auto.conf (which mirrors .config).
 834#
 835# This exploits the 'multi-target pattern rule' trick.
 836# The syncconfig should be executed only once to make all the targets.
 837# (Note: use the grouped target '&:' when we bump to GNU Make 4.3)
 838#
 839# Do not use $(call cmd,...) here. That would suppress prompts from syncconfig,
 840# so you cannot notice that Kconfig is waiting for the user input.
 841%/config/auto.conf %/config/auto.conf.cmd %/generated/autoconf.h %/generated/rustc_cfg: $(KCONFIG_CONFIG)
 842        $(Q)$(kecho) "  SYNC    $@"
 843        $(Q)$(MAKE) -f $(srctree)/Makefile syncconfig
 844else # !may-sync-config
 845# External modules and some install targets need include/generated/autoconf.h
 846# and include/config/auto.conf but do not care if they are up-to-date.
 847# Use auto.conf to show the error message
 848
 849checked-configs := $(addprefix $(objtree)/, include/generated/autoconf.h include/generated/rustc_cfg include/config/auto.conf)
 850missing-configs := $(filter-out $(wildcard $(checked-configs)), $(checked-configs))
 851
 852ifdef missing-configs
 853PHONY += $(objtree)/include/config/auto.conf
 854
 855$(objtree)/include/config/auto.conf:
 856        @echo   >&2 '***'
 857        @echo   >&2 '***  ERROR: Kernel configuration is invalid. The following files are missing:'
 858        @printf >&2 '***    - %s\n' $(missing-configs)
 859        @echo   >&2 '***  Run "make oldconfig && make prepare" on kernel source to fix it.'
 860        @echo   >&2 '***'
 861        @/bin/false
 862endif
 863
 864endif # may-sync-config
 865endif # need-config
 866
 867KBUILD_CFLAGS   += -fno-delete-null-pointer-checks
 868
 869ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
 870KBUILD_CFLAGS += -O2
 871KBUILD_RUSTFLAGS += -Copt-level=2
 872else ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
 873KBUILD_CFLAGS += -Os
 874KBUILD_RUSTFLAGS += -Copt-level=s
 875endif
 876
 877# Always set `debug-assertions` and `overflow-checks` because their default
 878# depends on `opt-level` and `debug-assertions`, respectively.
 879KBUILD_RUSTFLAGS += -Cdebug-assertions=$(if $(CONFIG_RUST_DEBUG_ASSERTIONS),y,n)
 880KBUILD_RUSTFLAGS += -Coverflow-checks=$(if $(CONFIG_RUST_OVERFLOW_CHECKS),y,n)
 881
 882# Tell gcc to never replace conditional load with a non-conditional one
 883ifdef CONFIG_CC_IS_GCC
 884# gcc-10 renamed --param=allow-store-data-races=0 to
 885# -fno-allow-store-data-races.
 886KBUILD_CFLAGS   += $(call cc-option,--param=allow-store-data-races=0)
 887KBUILD_CFLAGS   += $(call cc-option,-fno-allow-store-data-races)
 888endif
 889
 890ifdef CONFIG_READABLE_ASM
 891# Disable optimizations that make assembler listings hard to read.
 892# reorder blocks reorders the control in the function
 893# ipa clone creates specialized cloned functions
 894# partial inlining inlines only parts of functions
 895KBUILD_CFLAGS += -fno-reorder-blocks -fno-ipa-cp-clone -fno-partial-inlining
 896endif
 897
 898stackp-flags-y                                    := -fno-stack-protector
 899stackp-flags-$(CONFIG_STACKPROTECTOR)             := -fstack-protector
 900stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG)      := -fstack-protector-strong
 901
 902KBUILD_CFLAGS += $(stackp-flags-y)
 903
 904KBUILD_RUSTFLAGS-$(CONFIG_WERROR) += -Dwarnings
 905KBUILD_RUSTFLAGS += $(KBUILD_RUSTFLAGS-y)
 906
 907ifdef CONFIG_FRAME_POINTER
 908KBUILD_CFLAGS   += -fno-omit-frame-pointer -fno-optimize-sibling-calls
 909KBUILD_RUSTFLAGS += -Cforce-frame-pointers=y
 910else
 911# Some targets (ARM with Thumb2, for example), can't be built with frame
 912# pointers.  For those, we don't have FUNCTION_TRACER automatically
 913# select FRAME_POINTER.  However, FUNCTION_TRACER adds -pg, and this is
 914# incompatible with -fomit-frame-pointer with current GCC, so we don't use
 915# -fomit-frame-pointer with FUNCTION_TRACER.
 916# In the Rust target specification, "frame-pointer" is set explicitly
 917# to "may-omit".
 918ifndef CONFIG_FUNCTION_TRACER
 919KBUILD_CFLAGS   += -fomit-frame-pointer
 920endif
 921endif
 922
 923# Initialize all stack variables with a 0xAA pattern.
 924ifdef CONFIG_INIT_STACK_ALL_PATTERN
 925KBUILD_CFLAGS   += -ftrivial-auto-var-init=pattern
 926endif
 927
 928# Initialize all stack variables with a zero value.
 929ifdef CONFIG_INIT_STACK_ALL_ZERO
 930KBUILD_CFLAGS   += -ftrivial-auto-var-init=zero
 931ifdef CONFIG_CC_HAS_AUTO_VAR_INIT_ZERO_ENABLER
 932# https://github.com/llvm/llvm-project/issues/44842
 933CC_AUTO_VAR_INIT_ZERO_ENABLER := -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
 934export CC_AUTO_VAR_INIT_ZERO_ENABLER
 935KBUILD_CFLAGS   += $(CC_AUTO_VAR_INIT_ZERO_ENABLER)
 936endif
 937endif
 938
 939# Explicitly clear padding bits during variable initialization
 940KBUILD_CFLAGS += $(call cc-option,-fzero-init-padding-bits=all)
 941
 942# While VLAs have been removed, GCC produces unreachable stack probes
 943# for the randomize_kstack_offset feature. Disable it for all compilers.
 944KBUILD_CFLAGS   += $(call cc-option, -fno-stack-clash-protection)
 945
 946# Clear used registers at func exit (to reduce data lifetime and ROP gadgets).
 947ifdef CONFIG_ZERO_CALL_USED_REGS
 948KBUILD_CFLAGS   += -fzero-call-used-regs=used-gpr
 949endif
 950
 951ifdef CONFIG_FUNCTION_TRACER
 952ifdef CONFIG_FTRACE_MCOUNT_USE_CC
 953  CC_FLAGS_FTRACE       += -mrecord-mcount
 954  ifdef CONFIG_HAVE_NOP_MCOUNT
 955    ifeq ($(call cc-option-yn, -mnop-mcount),y)
 956      CC_FLAGS_FTRACE   += -mnop-mcount
 957      CC_FLAGS_USING    += -DCC_USING_NOP_MCOUNT
 958    endif
 959  endif
 960endif
 961ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
 962  ifdef CONFIG_HAVE_OBJTOOL_NOP_MCOUNT
 963    CC_FLAGS_USING      += -DCC_USING_NOP_MCOUNT
 964  endif
 965endif
 966ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
 967  ifdef CONFIG_HAVE_C_RECORDMCOUNT
 968    BUILD_C_RECORDMCOUNT := y
 969    export BUILD_C_RECORDMCOUNT
 970  endif
 971endif
 972ifdef CONFIG_HAVE_FENTRY
 973  # s390-linux-gnu-gcc did not support -mfentry until gcc-9.
 974  ifeq ($(call cc-option-yn, -mfentry),y)
 975    CC_FLAGS_FTRACE     += -mfentry
 976    CC_FLAGS_USING      += -DCC_USING_FENTRY
 977  endif
 978endif
 979export CC_FLAGS_FTRACE
 980KBUILD_CFLAGS   += $(CC_FLAGS_FTRACE) $(CC_FLAGS_USING)
 981KBUILD_AFLAGS   += $(CC_FLAGS_USING)
 982endif
 983
 984# We trigger additional mismatches with less inlining
 985ifdef CONFIG_DEBUG_SECTION_MISMATCH
 986KBUILD_CFLAGS += -fno-inline-functions-called-once
 987endif
 988
 989# `rustc`'s `-Zfunction-sections` applies to data too (as of 1.59.0).
 990ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
 991KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections
 992KBUILD_RUSTFLAGS_KERNEL += -Zfunction-sections=y
 993LDFLAGS_vmlinux += --gc-sections
 994endif
 995
 996ifdef CONFIG_SHADOW_CALL_STACK
 997ifndef CONFIG_DYNAMIC_SCS
 998CC_FLAGS_SCS    := -fsanitize=shadow-call-stack
 999KBUILD_CFLAGS   += $(CC_FLAGS_SCS)
1000KBUILD_RUSTFLAGS += -Zsanitizer=shadow-call-stack
1001endif
1002export CC_FLAGS_SCS
1003endif
1004
1005ifdef CONFIG_LTO_CLANG
1006ifdef CONFIG_LTO_CLANG_THIN
1007CC_FLAGS_LTO    := -flto=thin -fsplit-lto-unit
1008else
1009CC_FLAGS_LTO    := -flto
1010endif
1011CC_FLAGS_LTO    += -fvisibility=hidden
1012
1013# Limit inlining across translation units to reduce binary size
1014KBUILD_LDFLAGS += -mllvm -import-instr-limit=5
1015endif
1016
1017ifdef CONFIG_LTO
1018KBUILD_CFLAGS   += -fno-lto $(CC_FLAGS_LTO)
1019KBUILD_AFLAGS   += -fno-lto
1020export CC_FLAGS_LTO
1021endif
1022
1023ifdef CONFIG_CFI_CLANG
1024CC_FLAGS_CFI    := -fsanitize=kcfi
1025ifdef CONFIG_CFI_ICALL_NORMALIZE_INTEGERS
1026        CC_FLAGS_CFI    += -fsanitize-cfi-icall-experimental-normalize-integers
1027endif
1028ifdef CONFIG_FINEIBT_BHI
1029        CC_FLAGS_CFI    += -fsanitize-kcfi-arity
1030endif
1031ifdef CONFIG_RUST
1032        # Always pass -Zsanitizer-cfi-normalize-integers as CONFIG_RUST selects
1033        # CONFIG_CFI_ICALL_NORMALIZE_INTEGERS.
1034        RUSTC_FLAGS_CFI   := -Zsanitizer=kcfi -Zsanitizer-cfi-normalize-integers
1035        KBUILD_RUSTFLAGS += $(RUSTC_FLAGS_CFI)
1036        export RUSTC_FLAGS_CFI
1037endif
1038KBUILD_CFLAGS   += $(CC_FLAGS_CFI)
1039export CC_FLAGS_CFI
1040endif
1041
1042# Architectures can define flags to add/remove for floating-point support
1043CC_FLAGS_FPU    += -D_LINUX_FPU_COMPILATION_UNIT
1044export CC_FLAGS_FPU
1045export CC_FLAGS_NO_FPU
1046
1047ifneq ($(CONFIG_FUNCTION_ALIGNMENT),0)
1048# Set the minimal function alignment. Use the newer GCC option
1049# -fmin-function-alignment if it is available, or fall back to -falign-funtions.
1050# See also CONFIG_CC_HAS_SANE_FUNCTION_ALIGNMENT.
1051ifdef CONFIG_CC_HAS_MIN_FUNCTION_ALIGNMENT
1052KBUILD_CFLAGS += -fmin-function-alignment=$(CONFIG_FUNCTION_ALIGNMENT)
1053else
1054KBUILD_CFLAGS += -falign-functions=$(CONFIG_FUNCTION_ALIGNMENT)
1055endif
1056endif
1057
1058# arch Makefile may override CC so keep this after arch Makefile is included
1059NOSTDINC_FLAGS += -nostdinc
1060
1061# To gain proper coverage for CONFIG_UBSAN_BOUNDS and CONFIG_FORTIFY_SOURCE,
1062# the kernel uses only C99 flexible arrays for dynamically sized trailing
1063# arrays. Enforce this for everything that may examine structure sizes and
1064# perform bounds checking.
1065KBUILD_CFLAGS += $(call cc-option, -fstrict-flex-arrays=3)
1066
1067# disable invalid "can't wrap" optimizations for signed / pointers
1068KBUILD_CFLAGS   += -fno-strict-overflow
1069
1070# Make sure -fstack-check isn't enabled (like gentoo apparently did)
1071KBUILD_CFLAGS  += -fno-stack-check
1072
1073# conserve stack if available
1074ifdef CONFIG_CC_IS_GCC
1075KBUILD_CFLAGS   += -fconserve-stack
1076endif
1077
1078# Ensure compilers do not transform certain loops into calls to wcslen()
1079KBUILD_CFLAGS += -fno-builtin-wcslen
1080
1081# change __FILE__ to the relative path to the source directory
1082ifdef building_out_of_srctree
1083KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srcroot)/=)
1084endif
1085
1086# include additional Makefiles when needed
1087include-y                       := scripts/Makefile.extrawarn
1088include-$(CONFIG_DEBUG_INFO)    += scripts/Makefile.debug
1089include-$(CONFIG_DEBUG_INFO_BTF)+= scripts/Makefile.btf
1090include-$(CONFIG_KASAN)         += scripts/Makefile.kasan
1091include-$(CONFIG_KCSAN)         += scripts/Makefile.kcsan
1092include-$(CONFIG_KMSAN)         += scripts/Makefile.kmsan
1093include-$(CONFIG_UBSAN)         += scripts/Makefile.ubsan
1094include-$(CONFIG_KCOV)          += scripts/Makefile.kcov
1095include-$(CONFIG_RANDSTRUCT)    += scripts/Makefile.randstruct
1096include-$(CONFIG_KSTACK_ERASE)  += scripts/Makefile.kstack_erase
1097include-$(CONFIG_AUTOFDO_CLANG) += scripts/Makefile.autofdo
1098include-$(CONFIG_PROPELLER_CLANG)       += scripts/Makefile.propeller
1099include-$(CONFIG_GCC_PLUGINS)   += scripts/Makefile.gcc-plugins
1100
1101include $(addprefix $(srctree)/, $(include-y))
1102
1103# scripts/Makefile.gcc-plugins is intentionally included last.
1104# Do not add $(call cc-option,...) below this line. When you build the kernel
1105# from the clean source tree, the GCC plugins do not exist at this point.
1106
1107# Add user supplied CPPFLAGS, AFLAGS, CFLAGS and RUSTFLAGS as the last assignments
1108KBUILD_CPPFLAGS += $(KCPPFLAGS)
1109KBUILD_AFLAGS   += $(KAFLAGS)
1110KBUILD_CFLAGS   += $(KCFLAGS)
1111KBUILD_RUSTFLAGS += $(KRUSTFLAGS)
1112
1113KBUILD_LDFLAGS_MODULE += --build-id=sha1
1114LDFLAGS_vmlinux += --build-id=sha1
1115
1116KBUILD_LDFLAGS  += -z noexecstack
1117ifeq ($(CONFIG_LD_IS_BFD),y)
1118KBUILD_LDFLAGS  += $(call ld-option,--no-warn-rwx-segments)
1119endif
1120
1121ifeq ($(CONFIG_STRIP_ASM_SYMS),y)
1122LDFLAGS_vmlinux += -X
1123endif
1124
1125ifeq ($(CONFIG_RELR),y)
1126# ld.lld before 15 did not support -z pack-relative-relocs.
1127LDFLAGS_vmlinux += $(call ld-option,--pack-dyn-relocs=relr,-z pack-relative-relocs)
1128endif
1129
1130# We never want expected sections to be placed heuristically by the
1131# linker. All sections should be explicitly named in the linker script.
1132ifdef CONFIG_LD_ORPHAN_WARN
1133LDFLAGS_vmlinux += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
1134endif
1135
1136ifneq ($(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS),)
1137LDFLAGS_vmlinux += --emit-relocs --discard-none
1138endif
1139
1140# Align the bit size of userspace programs with the kernel
1141KBUILD_USERCFLAGS  += $(filter -m32 -m64 --target=%, $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
1142KBUILD_USERLDFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
1143
1144# userspace programs are linked via the compiler, use the correct linker
1145ifdef CONFIG_CC_IS_CLANG
1146KBUILD_USERLDFLAGS += --ld-path=$(LD)
1147endif
1148
1149# make the checker run with the right architecture
1150CHECKFLAGS += --arch=$(ARCH)
1151
1152# insure the checker run with the right endianness
1153CHECKFLAGS += $(if $(CONFIG_CPU_BIG_ENDIAN),-mbig-endian,-mlittle-endian)
1154
1155# the checker needs the correct machine size
1156CHECKFLAGS += $(if $(CONFIG_64BIT),-m64,-m32)
1157
1158# Default kernel image to build when no specific target is given.
1159# KBUILD_IMAGE may be overruled on the command line or
1160# set in the environment
1161# Also any assignments in arch/$(ARCH)/Makefile take precedence over
1162# this default value
1163export KBUILD_IMAGE ?= vmlinux
1164
1165#
1166# INSTALL_PATH specifies where to place the updated kernel and system map
1167# images. Default is /boot, but you can set it to other values
1168export  INSTALL_PATH ?= /boot
1169
1170#
1171# INSTALL_DTBS_PATH specifies a prefix for relocations required by build roots.
1172# Like INSTALL_MOD_PATH, it isn't defined in the Makefile, but can be passed as
1173# an argument if needed. Otherwise it defaults to the kernel install path
1174#
1175export INSTALL_DTBS_PATH ?= $(INSTALL_PATH)/dtbs/$(KERNELRELEASE)
1176
1177#
1178# INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
1179# relocations required by build roots.  This is not defined in the
1180# makefile but the argument can be passed to make if needed.
1181#
1182
1183MODLIB  = $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
1184export MODLIB
1185
1186PHONY += prepare0
1187
1188ifeq ($(KBUILD_EXTMOD),)
1189
1190build-dir       := .
1191clean-dirs      := $(sort . Documentation \
1192                     $(patsubst %/,%,$(filter %/, $(core-) \
1193                        $(drivers-) $(libs-))))
1194
1195export ARCH_CORE        := $(core-y)
1196export ARCH_LIB         := $(filter %/, $(libs-y))
1197export ARCH_DRIVERS     := $(drivers-y) $(drivers-m)
1198# Externally visible symbols (used by link-vmlinux.sh)
1199
1200KBUILD_VMLINUX_OBJS := built-in.a $(patsubst %/, %/lib.a, $(filter %/, $(libs-y)))
1201KBUILD_VMLINUX_LIBS := $(filter-out %/, $(libs-y))
1202
1203export KBUILD_VMLINUX_LIBS
1204export KBUILD_LDS          := arch/$(SRCARCH)/kernel/vmlinux.lds
1205
1206ifdef CONFIG_TRIM_UNUSED_KSYMS
1207# For the kernel to actually contain only the needed exported symbols,
1208# we have to build modules as well to determine what those symbols are.
1209KBUILD_MODULES := y
1210endif
1211
1212# '$(AR) mPi' needs 'T' to workaround the bug of llvm-ar <= 14
1213quiet_cmd_ar_vmlinux.a = AR      $@
1214      cmd_ar_vmlinux.a = \
1215        rm -f $@; \
1216        $(AR) cDPrST $@ $(KBUILD_VMLINUX_OBJS); \
1217        $(AR) mPiT $$($(AR) t $@ | sed -n 1p) $@ $$($(AR) t $@ | grep -F -f $(srctree)/scripts/head-object-list.txt)
1218
1219targets += vmlinux.a
1220vmlinux.a: $(KBUILD_VMLINUX_OBJS) scripts/head-object-list.txt FORCE
1221        $(call if_changed,ar_vmlinux.a)
1222
1223PHONY += vmlinux_o
1224vmlinux_o: vmlinux.a $(KBUILD_VMLINUX_LIBS)
1225        $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.vmlinux_o
1226
1227vmlinux.o modules.builtin.modinfo modules.builtin: vmlinux_o
1228        @:
1229
1230PHONY += vmlinux
1231# LDFLAGS_vmlinux in the top Makefile defines linker flags for the top vmlinux,
1232# not for decompressors. LDFLAGS_vmlinux in arch/*/boot/compressed/Makefile is
1233# unrelated; the decompressors just happen to have the same base name,
1234# arch/*/boot/compressed/vmlinux.
1235# Export LDFLAGS_vmlinux only to scripts/Makefile.vmlinux.
1236#
1237# _LDFLAGS_vmlinux is a workaround for the 'private export' bug:
1238#   https://savannah.gnu.org/bugs/?61463
1239# For Make > 4.4, the following simple code will work:
1240#  vmlinux: private export LDFLAGS_vmlinux := $(LDFLAGS_vmlinux)
1241vmlinux: private _LDFLAGS_vmlinux := $(LDFLAGS_vmlinux)
1242vmlinux: export LDFLAGS_vmlinux = $(_LDFLAGS_vmlinux)
1243vmlinux: vmlinux.o $(KBUILD_LDS) modpost
1244        $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.vmlinux
1245
1246# The actual objects are generated when descending,
1247# make sure no implicit rule kicks in
1248$(sort $(KBUILD_LDS) $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)): . ;
1249
1250ifeq ($(origin KERNELRELEASE),file)
1251filechk_kernel.release = $(srctree)/scripts/setlocalversion $(srctree)
1252else
1253filechk_kernel.release = echo $(KERNELRELEASE)
1254endif
1255
1256# Store (new) KERNELRELEASE string in include/config/kernel.release
1257include/config/kernel.release: FORCE
1258        $(call filechk,kernel.release)
1259
1260# Additional helpers built in scripts/
1261# Carefully list dependencies so we do not try to build scripts twice
1262# in parallel
1263PHONY += scripts
1264scripts: scripts_basic scripts_dtc
1265        $(Q)$(MAKE) $(build)=$(@)
1266
1267# Things we need to do before we recursively start building the kernel
1268# or the modules are listed in "prepare".
1269# A multi level approach is used. prepareN is processed before prepareN-1.
1270# archprepare is used in arch Makefiles and when processed asm symlink,
1271# version.h and scripts_basic is processed / created.
1272
1273PHONY += prepare archprepare
1274
1275archprepare: outputmakefile archheaders archscripts scripts include/config/kernel.release \
1276        asm-generic $(version_h) include/generated/utsrelease.h \
1277        include/generated/compile.h include/generated/autoconf.h \
1278        include/generated/rustc_cfg remove-stale-files
1279
1280prepare0: archprepare
1281        $(Q)$(MAKE) $(build)=scripts/mod
1282        $(Q)$(MAKE) $(build)=. prepare
1283
1284# All the preparing..
1285prepare: prepare0
1286ifdef CONFIG_RUST
1287        +$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh
1288        $(Q)$(MAKE) $(build)=rust
1289endif
1290
1291PHONY += remove-stale-files
1292remove-stale-files:
1293        $(Q)$(srctree)/scripts/remove-stale-files
1294
1295# Support for using generic headers in asm-generic
1296asm-generic := -f $(srctree)/scripts/Makefile.asm-headers obj
1297
1298PHONY += asm-generic uapi-asm-generic
1299asm-generic: uapi-asm-generic
1300        $(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/asm \
1301        generic=include/asm-generic
1302uapi-asm-generic:
1303        $(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/uapi/asm \
1304        generic=include/uapi/asm-generic
1305
1306# Generate some files
1307# ---------------------------------------------------------------------------
1308
1309# KERNELRELEASE can change from a few different places, meaning version.h
1310# needs to be updated, so this check is forced on all builds
1311
1312uts_len := 64
1313define filechk_utsrelease.h
1314        if [ `echo -n "$(KERNELRELEASE)" | wc -c ` -gt $(uts_len) ]; then \
1315          echo '"$(KERNELRELEASE)" exceeds $(uts_len) characters' >&2;    \
1316          exit 1;                                                         \
1317        fi;                                                               \
1318        echo \#define UTS_RELEASE \"$(KERNELRELEASE)\"
1319endef
1320
1321define filechk_version.h
1322        if [ $(SUBLEVEL) -gt 255 ]; then                                 \
1323                echo \#define LINUX_VERSION_CODE $(shell                 \
1324                expr $(VERSION) \* 65536 + $(PATCHLEVEL) \* 256 + 255); \
1325        else                                                             \
1326                echo \#define LINUX_VERSION_CODE $(shell                 \
1327                expr $(VERSION) \* 65536 + $(PATCHLEVEL) \* 256 + $(SUBLEVEL)); \
1328        fi;                                                              \
1329        echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) +  \
1330        ((c) > 255 ? 255 : (c)))';                                       \
1331        echo \#define LINUX_VERSION_MAJOR $(VERSION);                    \
1332        echo \#define LINUX_VERSION_PATCHLEVEL $(PATCHLEVEL);            \
1333        echo \#define LINUX_VERSION_SUBLEVEL $(SUBLEVEL)
1334endef
1335
1336$(version_h): private PATCHLEVEL := $(or $(PATCHLEVEL), 0)
1337$(version_h): private SUBLEVEL := $(or $(SUBLEVEL), 0)
1338$(version_h): FORCE
1339        $(call filechk,version.h)
1340
1341include/generated/utsrelease.h: include/config/kernel.release FORCE
1342        $(call filechk,utsrelease.h)
1343
1344filechk_compile.h = $(srctree)/scripts/mkcompile_h \
1345        "$(UTS_MACHINE)" "$(CONFIG_CC_VERSION_TEXT)" "$(LD)"
1346
1347include/generated/compile.h: FORCE
1348        $(call filechk,compile.h)
1349
1350PHONY += headerdep
1351headerdep:
1352        $(Q)find $(srctree)/include/ -name '*.h' | xargs --max-args 1 \
1353        $(srctree)/scripts/headerdep.pl -I$(srctree)/include
1354
1355# ---------------------------------------------------------------------------
1356# Kernel headers
1357
1358#Default location for installed headers
1359export INSTALL_HDR_PATH = $(objtree)/usr
1360
1361quiet_cmd_headers_install = INSTALL $(INSTALL_HDR_PATH)/include
1362      cmd_headers_install = \
1363        mkdir -p $(INSTALL_HDR_PATH); \
1364        rsync -mrl --include='*/' --include='*\.h' --exclude='*' \
1365        usr/include $(INSTALL_HDR_PATH)
1366
1367PHONY += headers_install
1368headers_install: headers
1369        $(call cmd,headers_install)
1370
1371PHONY += archheaders archscripts
1372
1373hdr-inst := -f $(srctree)/scripts/Makefile.headersinst obj
1374
1375PHONY += headers
1376headers: $(version_h) scripts_unifdef uapi-asm-generic archheaders
1377ifdef HEADER_ARCH
1378        $(Q)$(MAKE) -f $(srctree)/Makefile HEADER_ARCH= SRCARCH=$(HEADER_ARCH) headers
1379else
1380        $(Q)$(MAKE) $(hdr-inst)=include/uapi
1381        $(Q)$(MAKE) $(hdr-inst)=arch/$(SRCARCH)/include/uapi
1382endif
1383
1384ifdef CONFIG_HEADERS_INSTALL
1385prepare: headers
1386endif
1387
1388PHONY += scripts_unifdef
1389scripts_unifdef: scripts_basic
1390        $(Q)$(MAKE) $(build)=scripts scripts/unifdef
1391
1392PHONY += scripts_gen_packed_field_checks
1393scripts_gen_packed_field_checks: scripts_basic
1394        $(Q)$(MAKE) $(build)=scripts scripts/gen_packed_field_checks
1395
1396# ---------------------------------------------------------------------------
1397# Install
1398
1399# Many distributions have the custom install script, /sbin/installkernel.
1400# If DKMS is installed, 'make install' will eventually recurse back
1401# to this Makefile to build and install external modules.
1402# Cancel sub_make_done so that options such as M=, V=, etc. are parsed.
1403
1404quiet_cmd_install = INSTALL $(INSTALL_PATH)
1405      cmd_install = unset sub_make_done; $(srctree)/scripts/install.sh
1406
1407# ---------------------------------------------------------------------------
1408# vDSO install
1409
1410PHONY += vdso_install
1411vdso_install: export INSTALL_FILES = $(vdso-install-y)
1412vdso_install:
1413        $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.vdsoinst
1414
1415# ---------------------------------------------------------------------------
1416# Tools
1417
1418ifdef CONFIG_OBJTOOL
1419prepare: tools/objtool
1420endif
1421
1422ifdef CONFIG_BPF
1423ifdef CONFIG_DEBUG_INFO_BTF
1424prepare: tools/bpf/resolve_btfids
1425endif
1426endif
1427
1428# The tools build system is not a part of Kbuild and tends to introduce
1429# its own unique issues. If you need to integrate a new tool into Kbuild,
1430# please consider locating that tool outside the tools/ tree and using the
1431# standard Kbuild "hostprogs" syntax instead of adding a new tools/* entry
1432# here. See Documentation/kbuild/makefiles.rst for details.
1433
1434PHONY += resolve_btfids_clean
1435
1436resolve_btfids_O = $(abspath $(objtree))/tools/bpf/resolve_btfids
1437
1438# tools/bpf/resolve_btfids directory might not exist
1439# in output directory, skip its clean in that case
1440resolve_btfids_clean:
1441ifneq ($(wildcard $(resolve_btfids_O)),)
1442        $(Q)$(MAKE) -sC $(srctree)/tools/bpf/resolve_btfids O=$(resolve_btfids_O) clean
1443endif
1444
1445tools/: FORCE
1446        $(Q)mkdir -p $(objtree)/tools
1447        $(Q)$(MAKE) LDFLAGS= O=$(abspath $(objtree)) subdir=tools -C $(srctree)/tools/
1448
1449tools/%: FORCE
1450        $(Q)mkdir -p $(objtree)/tools
1451        $(Q)$(MAKE) LDFLAGS= O=$(abspath $(objtree)) subdir=tools -C $(srctree)/tools/ $*
1452
1453# ---------------------------------------------------------------------------
1454# Kernel selftest
1455
1456PHONY += kselftest
1457kselftest: headers
1458        $(Q)$(MAKE) -C $(srctree)/tools/testing/selftests run_tests
1459
1460kselftest-%: headers FORCE
1461        $(Q)$(MAKE) -C $(srctree)/tools/testing/selftests $*
1462
1463PHONY += kselftest-merge
1464kselftest-merge:
1465        $(if $(wildcard $(objtree)/.config),, $(error No .config exists, config your kernel first!))
1466        $(Q)find $(srctree)/tools/testing/selftests -name config -o -name config.$(UTS_MACHINE) | \
1467                xargs $(srctree)/scripts/kconfig/merge_config.sh -y -m $(objtree)/.config
1468        $(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
1469
1470# ---------------------------------------------------------------------------
1471# Devicetree files
1472
1473ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/boot/dts/),)
1474dtstree := arch/$(SRCARCH)/boot/dts
1475endif
1476
1477ifneq ($(dtstree),)
1478
1479%.dtb: dtbs_prepare
1480        $(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
1481
1482%.dtbo: dtbs_prepare
1483        $(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
1484
1485PHONY += dtbs dtbs_prepare dtbs_install dtbs_check
1486dtbs: dtbs_prepare
1487        $(Q)$(MAKE) $(build)=$(dtstree) need-dtbslist=1
1488
1489# include/config/kernel.release is actually needed when installing DTBs because
1490# INSTALL_DTBS_PATH contains $(KERNELRELEASE). However, we do not want to make
1491# dtbs_install depend on it as dtbs_install may run as root.
1492dtbs_prepare: include/config/kernel.release scripts_dtc
1493
1494ifneq ($(filter dtbs_check, $(MAKECMDGOALS)),)
1495export CHECK_DTBS=y
1496endif
1497
1498ifneq ($(CHECK_DTBS),)
1499dtbs_prepare: dt_binding_schemas
1500endif
1501
1502dtbs_check: dtbs
1503
1504dtbs_install:
1505        $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.dtbinst obj=$(dtstree)
1506
1507ifdef CONFIG_OF_EARLY_FLATTREE
1508all: dtbs
1509endif
1510
1511ifdef CONFIG_GENERIC_BUILTIN_DTB
1512vmlinux: dtbs
1513endif
1514
1515endif
1516
1517PHONY += scripts_dtc
1518scripts_dtc: scripts_basic
1519        $(Q)$(MAKE) $(build)=scripts/dtc
1520
1521ifneq ($(filter dt_binding_check, $(MAKECMDGOALS)),)
1522export CHECK_DTBS=y
1523endif
1524
1525PHONY += dt_binding_check dt_binding_schemas
1526dt_binding_check: dt_binding_schemas scripts_dtc
1527        $(Q)$(MAKE) $(build)=Documentation/devicetree/bindings $@
1528
1529dt_binding_schemas:
1530        $(Q)$(MAKE) $(build)=Documentation/devicetree/bindings
1531
1532PHONY += dt_compatible_check
1533dt_compatible_check: dt_binding_schemas
1534        $(Q)$(MAKE) $(build)=Documentation/devicetree/bindings $@
1535
1536# ---------------------------------------------------------------------------
1537# Modules
1538
1539ifdef CONFIG_MODULES
1540
1541# By default, build modules as well
1542
1543all: modules
1544
1545# When we're building modules with modversions, we need to consider
1546# the built-in objects during the descend as well, in order to
1547# make sure the checksums are up to date before we record them.
1548ifdef CONFIG_MODVERSIONS
1549  KBUILD_BUILTIN := y
1550endif
1551
1552# Build modules
1553#
1554
1555# *.ko are usually independent of vmlinux, but CONFIG_DEBUG_INFO_BTF_MODULES
1556# is an exception.
1557ifdef CONFIG_DEBUG_INFO_BTF_MODULES
1558KBUILD_BUILTIN := y
1559modules: vmlinux
1560endif
1561
1562modules: modules_prepare
1563
1564# Target to prepare building external modules
1565modules_prepare: prepare
1566        $(Q)$(MAKE) $(build)=scripts scripts/module.lds
1567
1568endif # CONFIG_MODULES
1569
1570###
1571# Cleaning is done on three levels.
1572# make clean     Delete most generated files
1573#                Leave enough to build external modules
1574# make mrproper  Delete the current configuration, and all generated files
1575# make distclean Remove editor backup files, patch leftover files and the like
1576
1577# Directories & files removed with 'make clean'
1578CLEAN_FILES += vmlinux.symvers modules-only.symvers \
1579               modules.builtin modules.builtin.modinfo modules.nsdeps \
1580               modules.builtin.ranges vmlinux.o.map vmlinux.unstripped \
1581               compile_commands.json rust/test \
1582               rust-project.json .vmlinux.objs .vmlinux.export.c \
1583               .builtin-dtbs-list .builtin-dtb.S
1584
1585# Directories & files removed with 'make mrproper'
1586MRPROPER_FILES += include/config include/generated          \
1587                  arch/$(SRCARCH)/include/generated .objdiff \
1588                  debian snap tar-install PKGBUILD pacman \
1589                  .config .config.old .version \
1590                  Module.symvers \
1591                  certs/signing_key.pem \
1592                  certs/x509.genkey \
1593                  vmlinux-gdb.py \
1594                  rpmbuild \
1595                  rust/libmacros.so rust/libmacros.dylib
1596
1597# clean - Delete most, but leave enough to build external modules
1598#
1599clean: private rm-files := $(CLEAN_FILES)
1600
1601PHONY += archclean vmlinuxclean
1602
1603vmlinuxclean:
1604        $(Q)$(CONFIG_SHELL) $(srctree)/scripts/link-vmlinux.sh clean
1605        $(Q)$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) clean)
1606
1607clean: archclean vmlinuxclean resolve_btfids_clean
1608
1609# mrproper - Delete all generated files, including .config
1610#
1611mrproper: private rm-files := $(MRPROPER_FILES)
1612mrproper-dirs      := $(addprefix _mrproper_,scripts)
1613
1614PHONY += $(mrproper-dirs) mrproper
1615$(mrproper-dirs):
1616        $(Q)$(MAKE) $(clean)=$(patsubst _mrproper_%,%,$@)
1617
1618mrproper: clean $(mrproper-dirs)
1619        $(call cmd,rmfiles)
1620        @find . $(RCS_FIND_IGNORE) \
1621                \( -name '*.rmeta' \) \
1622                -type f -print | xargs rm -f
1623
1624# distclean
1625#
1626PHONY += distclean
1627
1628distclean: mrproper
1629        @find . $(RCS_FIND_IGNORE) \
1630                \( -name '*.orig' -o -name '*.rej' -o -name '*~' \
1631                -o -name '*.bak' -o -name '#*#' -o -name '*%' \
1632                -o -name 'core' -o -name tags -o -name TAGS -o -name 'cscope*' \
1633                -o -name GPATH -o -name GRTAGS -o -name GSYMS -o -name GTAGS \) \
1634                -type f -print | xargs rm -f
1635
1636
1637# Packaging of the kernel to various formats
1638# ---------------------------------------------------------------------------
1639
1640%src-pkg: FORCE
1641        $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.package $@
1642%pkg: include/config/kernel.release FORCE
1643        $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.package $@
1644
1645# Brief documentation of the typical targets used
1646# ---------------------------------------------------------------------------
1647
1648boards := $(wildcard $(srctree)/arch/$(SRCARCH)/configs/*_defconfig)
1649boards := $(sort $(notdir $(boards)))
1650board-dirs := $(dir $(wildcard $(srctree)/arch/$(SRCARCH)/configs/*/*_defconfig))
1651board-dirs := $(sort $(notdir $(board-dirs:/=)))
1652
1653PHONY += help
1654help:
1655        @echo  'Cleaning targets:'
1656        @echo  '  clean           - Remove most generated files but keep the config and'
1657        @echo  '                    enough build support to build external modules'
1658        @echo  '  mrproper        - Remove all generated files + config + various backup files'
1659        @echo  '  distclean       - mrproper + remove editor backup and patch files'
1660        @echo  ''
1661        @$(MAKE) -f $(srctree)/scripts/kconfig/Makefile help
1662        @echo  ''
1663        @echo  'Other generic targets:'
1664        @echo  '  all             - Build all targets marked with [*]'
1665        @echo  '* vmlinux         - Build the bare kernel'
1666        @echo  '* modules         - Build all modules'
1667        @echo  '  modules_install - Install all modules to INSTALL_MOD_PATH (default: /)'
1668        @echo  '  vdso_install    - Install unstripped vdso to INSTALL_MOD_PATH (default: /)'
1669        @echo  '  dir/            - Build all files in dir and below'
1670        @echo  '  dir/file.[ois]  - Build specified target only'
1671        @echo  '  dir/file.ll     - Build the LLVM assembly file'
1672        @echo  '                    (requires compiler support for LLVM assembly generation)'
1673        @echo  '  dir/file.lst    - Build specified mixed source/assembly target only'
1674        @echo  '                    (requires a recent binutils and recent build (System.map))'
1675        @echo  '  dir/file.ko     - Build module including final link'
1676        @echo  '  modules_prepare - Set up for building external modules'
1677        @echo  '  tags/TAGS       - Generate tags file for editors'
1678        @echo  '  cscope          - Generate cscope index'
1679        @echo  '  gtags           - Generate GNU GLOBAL index'
1680        @echo  '  kernelrelease   - Output the release version string (use with make -s)'
1681        @echo  '  kernelversion   - Output the version stored in Makefile (use with make -s)'
1682        @echo  '  image_name      - Output the image name (use with make -s)'
1683        @echo  '  headers         - Build ready-to-install UAPI headers in usr/include'
1684        @echo  '  headers_install - Install sanitised kernel UAPI headers to INSTALL_HDR_PATH'; \
1685         echo  '                    (default: $(INSTALL_HDR_PATH))'; \
1686         echo  ''
1687        @echo  'Static analysers:'
1688        @echo  '  checkstack      - Generate a list of stack hogs and consider all functions'
1689        @echo  '                    with a stack size larger than MINSTACKSIZE (default: 100)'
1690        @echo  '  versioncheck    - Sanity check on version.h usage'
1691        @echo  '  includecheck    - Check for duplicate included header files'
1692        @echo  '  headerdep       - Detect inclusion cycles in headers'
1693        @echo  '  coccicheck      - Check with Coccinelle'
1694        @echo  '  clang-analyzer  - Check with clang static analyzer'
1695        @echo  '  clang-tidy      - Check with clang-tidy'
1696        @echo  ''
1697        @echo  'Tools:'
1698        @echo  '  nsdeps          - Generate missing symbol namespace dependencies'
1699        @echo  ''
1700        @echo  'Kernel selftest:'
1701        @echo  '  kselftest         - Build and run kernel selftest'
1702        @echo  '                      Build, install, and boot kernel before'
1703        @echo  '                      running kselftest on it'
1704        @echo  '                      Run as root for full coverage'
1705        @echo  '  kselftest-all     - Build kernel selftest'
1706        @echo  '  kselftest-install - Build and install kernel selftest'
1707        @echo  '  kselftest-clean   - Remove all generated kselftest files'
1708        @echo  '  kselftest-merge   - Merge all the config dependencies of'
1709        @echo  '                      kselftest to existing .config.'
1710        @echo  ''
1711        @echo  'Rust targets:'
1712        @echo  '  rustavailable   - Checks whether the Rust toolchain is'
1713        @echo  '                    available and, if not, explains why.'
1714        @echo  '  rustfmt         - Reformat all the Rust code in the kernel'
1715        @echo  '  rustfmtcheck    - Checks if all the Rust code in the kernel'
1716        @echo  '                    is formatted, printing a diff otherwise.'
1717        @echo  '  rustdoc         - Generate Rust documentation'
1718        @echo  '                    (requires kernel .config)'
1719        @echo  '  rusttest        - Runs the Rust tests'
1720        @echo  '                    (requires kernel .config; downloads external repos)'
1721        @echo  '  rust-analyzer   - Generate rust-project.json rust-analyzer support file'
1722        @echo  '                    (requires kernel .config)'
1723        @echo  '  dir/file.[os]   - Build specified target only'
1724        @echo  '  dir/file.rsi    - Build macro expanded source, similar to C preprocessing.'
1725        @echo  '                    Run with RUSTFMT=n to skip reformatting if needed.'
1726        @echo  '                    The output is not intended to be compilable.'
1727        @echo  '  dir/file.ll     - Build the LLVM assembly file'
1728        @echo  ''
1729        @$(if $(dtstree), \
1730                echo 'Devicetree:'; \
1731                echo '* dtbs               - Build device tree blobs for enabled boards'; \
1732                echo '  dtbs_install       - Install dtbs to $(INSTALL_DTBS_PATH)'; \
1733                echo '  dt_binding_check   - Validate device tree binding documents and examples'; \
1734                echo '  dt_binding_schemas - Build processed device tree binding schemas'; \
1735                echo '  dtbs_check         - Validate device tree source files';\
1736                echo '')
1737
1738        @echo 'Userspace tools targets:'
1739        @echo '  use "make tools/help"'
1740        @echo '  or  "cd tools; make help"'
1741        @echo  ''
1742        @echo  'Kernel packaging:'
1743        @$(MAKE) -f $(srctree)/scripts/Makefile.package help
1744        @echo  ''
1745        @echo  'Documentation targets:'
1746        @$(MAKE) -f $(srctree)/Documentation/Makefile dochelp
1747        @echo  ''
1748        @echo  'Architecture-specific targets ($(SRCARCH)):'
1749        @$(or $(archhelp),\
1750                echo '  No architecture-specific help defined for $(SRCARCH)')
1751        @echo  ''
1752        @$(if $(boards), \
1753                $(foreach b, $(boards), \
1754                printf "  %-27s - Build for %s\\n" $(b) $(subst _defconfig,,$(b));) \
1755                echo '')
1756        @$(if $(board-dirs), \
1757                $(foreach b, $(board-dirs), \
1758                printf "  %-16s - Show %s-specific targets\\n" help-$(b) $(b);) \
1759                printf "  %-16s - Show all of the above\\n" help-boards; \
1760                echo '')
1761
1762        @echo  '  make V=n   [targets] 1: verbose build'
1763        @echo  '                       2: give reason for rebuild of target'
1764        @echo  '                       V=1 and V=2 can be combined with V=12'
1765        @echo  '  make O=dir [targets] Locate all output files in "dir", including .config'
1766        @echo  '  make C=1   [targets] Check re-compiled c source with $$CHECK'
1767        @echo  '                       (sparse by default)'
1768        @echo  '  make C=2   [targets] Force check of all c source with $$CHECK'
1769        @echo  '  make RECORDMCOUNT_WARN=1 [targets] Warn about ignored mcount sections'
1770        @echo  '  make W=n   [targets] Enable extra build checks, n=1,2,3,c,e where'
1771        @echo  '                1: warnings which may be relevant and do not occur too often'
1772        @echo  '                2: warnings which occur quite often but may still be relevant'
1773        @echo  '                3: more obscure warnings, can most likely be ignored'
1774        @echo  '                c: extra checks in the configuration stage (Kconfig)'
1775        @echo  '                e: warnings are being treated as errors'
1776        @echo  '                Multiple levels can be combined with W=12 or W=123'
1777        @$(if $(dtstree), \
1778                echo '  make CHECK_DTBS=1 [targets] Check all generated dtb files against schema'; \
1779                echo '         This can be applied both to "dtbs" and to individual "foo.dtb" targets' ; \
1780                )
1781        @echo  ''
1782        @echo  'Execute "make" or "make all" to build all targets marked with [*] '
1783        @echo  'For further info see the ./README file'
1784
1785
1786help-board-dirs := $(addprefix help-,$(board-dirs))
1787
1788help-boards: $(help-board-dirs)
1789
1790boards-per-dir = $(sort $(notdir $(wildcard $(srctree)/arch/$(SRCARCH)/configs/$*/*_defconfig)))
1791
1792$(help-board-dirs): help-%:
1793        @echo  'Architecture-specific targets ($(SRCARCH) $*):'
1794        @$(if $(boards-per-dir), \
1795                $(foreach b, $(boards-per-dir), \
1796                printf "  %-24s - Build for %s\\n" $*/$(b) $(subst _defconfig,,$(b));) \
1797                echo '')
1798
1799
1800# Documentation targets
1801# ---------------------------------------------------------------------------
1802DOC_TARGETS := xmldocs latexdocs pdfdocs htmldocs epubdocs cleandocs \
1803               linkcheckdocs dochelp refcheckdocs texinfodocs infodocs
1804PHONY += $(DOC_TARGETS)
1805$(DOC_TARGETS):
1806        $(Q)$(MAKE) $(build)=Documentation $@
1807
1808
1809# Rust targets
1810# ---------------------------------------------------------------------------
1811
1812# "Is Rust available?" target
1813PHONY += rustavailable
1814rustavailable:
1815        +$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh && echo "Rust is available!"
1816
1817# Documentation target
1818#
1819# Using the singular to avoid running afoul of `no-dot-config-targets`.
1820PHONY += rustdoc
1821rustdoc: prepare
1822        $(Q)$(MAKE) $(build)=rust $@
1823
1824# Testing target
1825PHONY += rusttest
1826rusttest: prepare
1827        $(Q)$(MAKE) $(build)=rust $@
1828
1829# Formatting targets
1830PHONY += rustfmt rustfmtcheck
1831
1832rustfmt:
1833        $(Q)find $(srctree) $(RCS_FIND_IGNORE) \
1834                -type f -a -name '*.rs' -a ! -name '*generated*' -print \
1835                | xargs $(RUSTFMT) $(rustfmt_flags)
1836
1837rustfmtcheck: rustfmt_flags = --check
1838rustfmtcheck: rustfmt
1839
1840# Misc
1841# ---------------------------------------------------------------------------
1842
1843PHONY += misc-check
1844misc-check:
1845        $(Q)$(srctree)/scripts/misc-check
1846
1847all: misc-check
1848
1849PHONY += scripts_gdb
1850scripts_gdb: prepare0
1851        $(Q)$(MAKE) $(build)=scripts/gdb
1852        $(Q)ln -fsn $(abspath $(srctree)/scripts/gdb/vmlinux-gdb.py)
1853
1854ifdef CONFIG_GDB_SCRIPTS
1855all: scripts_gdb
1856endif
1857
1858else # KBUILD_EXTMOD
1859
1860filechk_kernel.release = echo $(KERNELRELEASE)
1861
1862###
1863# External module support.
1864# When building external modules the kernel used as basis is considered
1865# read-only, and no consistency checks are made and the make
1866# system is not used on the basis kernel. If updates are required
1867# in the basis kernel ordinary make commands (without M=...) must be used.
1868
1869# We are always building only modules.
1870KBUILD_BUILTIN :=
1871KBUILD_MODULES := y
1872
1873build-dir := .
1874
1875clean-dirs := .
1876clean: private rm-files := Module.symvers modules.nsdeps compile_commands.json
1877
1878PHONY += prepare
1879# now expand this into a simple variable to reduce the cost of shell evaluations
1880prepare: CC_VERSION_TEXT := $(CC_VERSION_TEXT)
1881prepare:
1882        @if [ "$(CC_VERSION_TEXT)" != "$(CONFIG_CC_VERSION_TEXT)" ]; then \
1883                echo >&2 "warning: the compiler differs from the one used to build the kernel"; \
1884                echo >&2 "  The kernel was built by: $(CONFIG_CC_VERSION_TEXT)"; \
1885                echo >&2 "  You are using:           $(CC_VERSION_TEXT)"; \
1886        fi
1887
1888PHONY += help
1889help:
1890        @echo  '  Building external modules.'
1891        @echo  '  Syntax: make -C path/to/kernel/src M=$$PWD target'
1892        @echo  ''
1893        @echo  '  modules         - default target, build the module(s)'
1894        @echo  '  modules_install - install the module'
1895        @echo  '  clean           - remove generated files in module directory only'
1896        @echo  '  rust-analyzer   - generate rust-project.json rust-analyzer support file'
1897        @echo  ''
1898
1899ifndef CONFIG_MODULES
1900modules modules_install: __external_modules_error
1901__external_modules_error:
1902        @echo >&2 '***'
1903        @echo >&2 '*** The present kernel disabled CONFIG_MODULES.'
1904        @echo >&2 '*** You cannot build or install external modules.'
1905        @echo >&2 '***'
1906        @false
1907endif
1908
1909endif # KBUILD_EXTMOD
1910
1911# ---------------------------------------------------------------------------
1912# Modules
1913
1914PHONY += modules modules_install modules_sign modules_prepare
1915
1916modules_install:
1917        $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst \
1918        sign-only=$(if $(filter modules_install,$(MAKECMDGOALS)),,y)
1919
1920ifeq ($(CONFIG_MODULE_SIG),y)
1921# modules_sign is a subset of modules_install.
1922# 'make modules_install modules_sign' is equivalent to 'make modules_install'.
1923modules_sign: modules_install
1924        @:
1925else
1926modules_sign:
1927        @echo >&2 '***'
1928        @echo >&2 '*** CONFIG_MODULE_SIG is disabled. You cannot sign modules.'
1929        @echo >&2 '***'
1930        @false
1931endif
1932
1933ifdef CONFIG_MODULES
1934
1935modules.order: $(build-dir)
1936        @:
1937
1938# KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
1939# This is solely useful to speed up test compiles.
1940modules: modpost
1941ifneq ($(KBUILD_MODPOST_NOFINAL),1)
1942        $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modfinal
1943endif
1944
1945PHONY += modules_check
1946modules_check: modules.order
1947        $(Q)$(CONFIG_SHELL) $(srctree)/scripts/modules-check.sh $<
1948
1949else # CONFIG_MODULES
1950
1951modules:
1952        @:
1953
1954KBUILD_MODULES :=
1955
1956endif # CONFIG_MODULES
1957
1958PHONY += modpost
1959modpost: $(if $(single-build),, $(if $(KBUILD_BUILTIN), vmlinux.o)) \
1960         $(if $(KBUILD_MODULES), modules_check)
1961        $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
1962
1963# Single targets
1964# ---------------------------------------------------------------------------
1965# To build individual files in subdirectories, you can do like this:
1966#
1967#   make foo/bar/baz.s
1968#
1969# The supported suffixes for single-target are listed in 'single-targets'
1970#
1971# To build only under specific subdirectories, you can do like this:
1972#
1973#   make foo/bar/baz/
1974
1975ifdef single-build
1976
1977# .ko is special because modpost is needed
1978single-ko := $(sort $(filter %.ko, $(MAKECMDGOALS)))
1979single-no-ko := $(filter-out $(single-ko), $(MAKECMDGOALS)) \
1980                $(foreach x, o mod, $(patsubst %.ko, %.$x, $(single-ko)))
1981
1982$(single-ko): single_modules
1983        @:
1984$(single-no-ko): $(build-dir)
1985        @:
1986
1987# Remove modules.order when done because it is not the real one.
1988PHONY += single_modules
1989single_modules: $(single-no-ko) modules_prepare
1990        $(Q){ $(foreach m, $(single-ko), echo $(m:%.ko=%.o);) } > modules.order
1991        $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
1992ifneq ($(KBUILD_MODPOST_NOFINAL),1)
1993        $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modfinal
1994endif
1995        $(Q)rm -f modules.order
1996
1997single-goals := $(addprefix $(build-dir)/, $(single-no-ko))
1998
1999KBUILD_MODULES := y
2000
2001endif
2002
2003prepare: outputmakefile
2004
2005# Preset locale variables to speed up the build process. Limit locale
2006# tweaks to this spot to avoid wrong language settings when running
2007# make menuconfig etc.
2008# Error messages still appears in the original language
2009PHONY += $(build-dir)
2010$(build-dir): prepare
2011        $(Q)$(MAKE) $(build)=$@ need-builtin=1 need-modorder=1 $(single-goals)
2012
2013clean-dirs := $(addprefix _clean_, $(clean-dirs))
2014PHONY += $(clean-dirs) clean
2015$(clean-dirs):
2016        $(Q)$(MAKE) $(clean)=$(patsubst _clean_%,%,$@)
2017
2018clean: $(clean-dirs)
2019        $(call cmd,rmfiles)
2020        @find . $(RCS_FIND_IGNORE) \
2021                \( -name '*.[aios]' -o -name '*.rsi' -o -name '*.ko' -o -name '.*.cmd' \
2022                -o -name '*.ko.*' \
2023                -o -name '*.dtb' -o -name '*.dtbo' \
2024                -o -name '*.dtb.S' -o -name '*.dtbo.S' \
2025                -o -name '*.dt.yaml' -o -name 'dtbs-list' \
2026                -o -name '*.dwo' -o -name '*.lst' \
2027                -o -name '*.su' -o -name '*.mod' \
2028                -o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
2029                -o -name '*.lex.c' -o -name '*.tab.[ch]' \
2030                -o -name '*.asn1.[ch]' \
2031                -o -name '*.symtypes' -o -name 'modules.order' \
2032                -o -name '*.c.[012]*.*' \
2033                -o -name '*.ll' \
2034                -o -name '*.gcno' \
2035                \) -type f -print \
2036                -o -name '.tmp_*' -print \
2037                | xargs rm -rf
2038
2039# Generate tags for editors
2040# ---------------------------------------------------------------------------
2041quiet_cmd_tags = GEN     $@
2042      cmd_tags = $(BASH) $(srctree)/scripts/tags.sh $@
2043
2044tags TAGS cscope gtags: FORCE
2045        $(call cmd,tags)
2046
2047# Generate rust-project.json (a file that describes the structure of non-Cargo
2048# Rust projects) for rust-analyzer (an implementation of the Language Server
2049# Protocol).
2050PHONY += rust-analyzer
2051rust-analyzer:
2052        +$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh
2053ifdef KBUILD_EXTMOD
2054# FIXME: external modules must not descend into a sub-directory of the kernel
2055        $(Q)$(MAKE) $(build)=$(objtree)/rust src=$(srctree)/rust $@
2056else
2057        $(Q)$(MAKE) $(build)=rust $@
2058endif
2059
2060# Script to generate missing namespace dependencies
2061# ---------------------------------------------------------------------------
2062
2063PHONY += nsdeps
2064nsdeps: export KBUILD_NSDEPS=1
2065nsdeps: modules
2066        $(Q)$(CONFIG_SHELL) $(srctree)/scripts/nsdeps
2067
2068# Clang Tooling
2069# ---------------------------------------------------------------------------
2070
2071quiet_cmd_gen_compile_commands = GEN     $@
2072      cmd_gen_compile_commands = $(PYTHON3) $< -a $(AR) -o $@ $(filter-out $<, $(real-prereqs))
2073
2074compile_commands.json: $(srctree)/scripts/clang-tools/gen_compile_commands.py \
2075        $(if $(KBUILD_EXTMOD),, vmlinux.a $(KBUILD_VMLINUX_LIBS)) \
2076        $(if $(CONFIG_MODULES), modules.order) FORCE
2077        $(call if_changed,gen_compile_commands)
2078
2079targets += compile_commands.json
2080
2081PHONY += clang-tidy clang-analyzer
2082
2083ifdef CONFIG_CC_IS_CLANG
2084quiet_cmd_clang_tools = CHECK   $<
2085      cmd_clang_tools = $(PYTHON3) $(srctree)/scripts/clang-tools/run-clang-tools.py $@ $<
2086
2087clang-tidy clang-analyzer: compile_commands.json
2088        $(call cmd,clang_tools)
2089else
2090clang-tidy clang-analyzer:
2091        @echo "$@ requires CC=clang" >&2
2092        @false
2093endif
2094
2095# Scripts to check various things for consistency
2096# ---------------------------------------------------------------------------
2097
2098PHONY += includecheck versioncheck coccicheck
2099
2100includecheck:
2101        find $(srctree)/* $(RCS_FIND_IGNORE) \
2102                -name '*.[hcS]' -type f -print | sort \
2103                | xargs $(PERL) -w $(srctree)/scripts/checkincludes.pl
2104
2105versioncheck:
2106        find $(srctree)/* $(RCS_FIND_IGNORE) \
2107                -name '*.[hcS]' -type f -print | sort \
2108                | xargs $(PERL) -w $(srctree)/scripts/checkversion.pl
2109
2110coccicheck:
2111        $(Q)$(BASH) $(srctree)/scripts/$@
2112
2113PHONY += checkstack kernelrelease kernelversion image_name
2114
2115# UML needs a little special treatment here.  It wants to use the host
2116# toolchain, so needs $(SUBARCH) passed to checkstack.pl.  Everyone
2117# else wants $(ARCH), including people doing cross-builds, which means
2118# that $(SUBARCH) doesn't work here.
2119ifeq ($(ARCH), um)
2120CHECKSTACK_ARCH := $(SUBARCH)
2121else
2122CHECKSTACK_ARCH := $(ARCH)
2123endif
2124MINSTACKSIZE    ?= 100
2125checkstack:
2126        $(OBJDUMP) -d vmlinux $$(find . -name '*.ko') | \
2127        $(PERL) $(srctree)/scripts/checkstack.pl $(CHECKSTACK_ARCH) $(MINSTACKSIZE)
2128
2129kernelrelease:
2130        @$(filechk_kernel.release)
2131
2132kernelversion:
2133        @echo $(KERNELVERSION)
2134
2135image_name:
2136        @echo $(KBUILD_IMAGE)
2137
2138PHONY += run-command
2139run-command:
2140        $(Q)$(KBUILD_RUN_COMMAND)
2141
2142quiet_cmd_rmfiles = $(if $(wildcard $(rm-files)),CLEAN   $(wildcard $(rm-files)))
2143      cmd_rmfiles = rm -rf $(rm-files)
2144
2145# read saved command lines for existing targets
2146existing-targets := $(wildcard $(sort $(targets)))
2147
2148-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
2149
2150endif # config-build
2151endif # mixed-build
2152endif # need-sub-make
2153
2154PHONY += FORCE
2155FORCE:
2156
2157# Declare the contents of the PHONY variable as phony.  We keep that
2158# information in a variable so we can use it in if_changed and friends.
2159.PHONY: $(PHONY)
2160