xref: /linux/Makefile (revision ff79d31eb536f6d87bcbc09287d54d5606bf6dbe)
1# SPDX-License-Identifier: GPL-2.0
2VERSION = 6
3PATCHLEVEL = 19
4SUBLEVEL = 0
5EXTRAVERSION = -rc1
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 := $(LLVM)
450else ifneq ($(LLVM),1)
451$(error Invalid value for LLVM, see Documentation/kbuild/llvm.rst)
452endif
453
454HOSTCC	= $(LLVM_PREFIX)clang$(LLVM_SUFFIX)
455HOSTCXX	= $(LLVM_PREFIX)clang++$(LLVM_SUFFIX)
456else
457HOSTCC	= gcc
458HOSTCXX	= g++
459endif
460HOSTRUSTC = rustc
461HOSTPKG_CONFIG	= pkg-config
462
463# the KERNELDOC macro needs to be exported, as scripts/Makefile.build
464# has a logic to call it
465KERNELDOC       = $(srctree)/scripts/kernel-doc.py
466export KERNELDOC
467
468KBUILD_USERHOSTCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
469			 -O2 -fomit-frame-pointer -std=gnu11
470KBUILD_USERCFLAGS  := $(KBUILD_USERHOSTCFLAGS) $(USERCFLAGS)
471KBUILD_USERLDFLAGS := $(USERLDFLAGS)
472
473# These flags apply to all Rust code in the tree, including the kernel and
474# host programs.
475export rust_common_flags := --edition=2021 \
476			    -Zbinary_dep_depinfo=y \
477			    -Astable_features \
478			    -Dnon_ascii_idents \
479			    -Dunsafe_op_in_unsafe_fn \
480			    -Wmissing_docs \
481			    -Wrust_2018_idioms \
482			    -Wunreachable_pub \
483			    -Wclippy::all \
484			    -Wclippy::as_ptr_cast_mut \
485			    -Wclippy::as_underscore \
486			    -Wclippy::cast_lossless \
487			    -Wclippy::ignored_unit_patterns \
488			    -Wclippy::mut_mut \
489			    -Wclippy::needless_bitwise_bool \
490			    -Aclippy::needless_lifetimes \
491			    -Wclippy::no_mangle_with_rust_abi \
492			    -Wclippy::ptr_as_ptr \
493			    -Wclippy::ptr_cast_constness \
494			    -Wclippy::ref_as_ptr \
495			    -Wclippy::undocumented_unsafe_blocks \
496			    -Wclippy::unnecessary_safety_comment \
497			    -Wclippy::unnecessary_safety_doc \
498			    -Wrustdoc::missing_crate_level_docs \
499			    -Wrustdoc::unescaped_backticks
500
501KBUILD_HOSTCFLAGS   := $(KBUILD_USERHOSTCFLAGS) $(HOST_LFS_CFLAGS) \
502		       $(HOSTCFLAGS) -I $(srctree)/scripts/include
503KBUILD_HOSTCXXFLAGS := -Wall -O2 $(HOST_LFS_CFLAGS) $(HOSTCXXFLAGS) \
504		       -I $(srctree)/scripts/include
505KBUILD_HOSTRUSTFLAGS := $(rust_common_flags) -O -Cstrip=debuginfo \
506			-Zallow-features= $(HOSTRUSTFLAGS)
507KBUILD_HOSTLDFLAGS  := $(HOST_LFS_LDFLAGS) $(HOSTLDFLAGS)
508KBUILD_HOSTLDLIBS   := $(HOST_LFS_LIBS) $(HOSTLDLIBS)
509KBUILD_PROCMACROLDFLAGS := $(or $(PROCMACROLDFLAGS),$(KBUILD_HOSTLDFLAGS))
510
511# Make variables (CC, etc...)
512CPP		= $(CC) -E
513ifneq ($(LLVM),)
514CC		= $(LLVM_PREFIX)clang$(LLVM_SUFFIX)
515LD		= $(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX)
516AR		= $(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX)
517NM		= $(LLVM_PREFIX)llvm-nm$(LLVM_SUFFIX)
518OBJCOPY		= $(LLVM_PREFIX)llvm-objcopy$(LLVM_SUFFIX)
519OBJDUMP		= $(LLVM_PREFIX)llvm-objdump$(LLVM_SUFFIX)
520READELF		= $(LLVM_PREFIX)llvm-readelf$(LLVM_SUFFIX)
521STRIP		= $(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX)
522else
523CC		= $(CROSS_COMPILE)gcc
524LD		= $(CROSS_COMPILE)ld
525AR		= $(CROSS_COMPILE)ar
526NM		= $(CROSS_COMPILE)nm
527OBJCOPY		= $(CROSS_COMPILE)objcopy
528OBJDUMP		= $(CROSS_COMPILE)objdump
529READELF		= $(CROSS_COMPILE)readelf
530STRIP		= $(CROSS_COMPILE)strip
531endif
532RUSTC		= rustc
533RUSTDOC		= rustdoc
534RUSTFMT		= rustfmt
535CLIPPY_DRIVER	= clippy-driver
536BINDGEN		= bindgen
537PAHOLE		= pahole
538RESOLVE_BTFIDS	= $(objtree)/tools/bpf/resolve_btfids/resolve_btfids
539LEX		= flex
540YACC		= bison
541AWK		= awk
542INSTALLKERNEL  := installkernel
543PERL		= perl
544PYTHON3		= python3
545CHECK		= sparse
546BASH		= bash
547KGZIP		= gzip
548KBZIP2		= bzip2
549KLZOP		= lzop
550LZMA		= lzma
551LZ4		= lz4
552XZ		= xz
553ZSTD		= zstd
554TAR		= tar
555
556CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
557		  -Wbitwise -Wno-return-void -Wno-unknown-attribute $(CF)
558NOSTDINC_FLAGS :=
559CFLAGS_MODULE   =
560RUSTFLAGS_MODULE =
561AFLAGS_MODULE   =
562LDFLAGS_MODULE  =
563CFLAGS_KERNEL	=
564RUSTFLAGS_KERNEL =
565AFLAGS_KERNEL	=
566LDFLAGS_vmlinux =
567
568# Use USERINCLUDE when you must reference the UAPI directories only.
569USERINCLUDE    := \
570		-I$(srctree)/arch/$(SRCARCH)/include/uapi \
571		-I$(objtree)/arch/$(SRCARCH)/include/generated/uapi \
572		-I$(srctree)/include/uapi \
573		-I$(objtree)/include/generated/uapi \
574                -include $(srctree)/include/linux/compiler-version.h \
575                -include $(srctree)/include/linux/kconfig.h
576
577# Use LINUXINCLUDE when you must reference the include/ directory.
578# Needed to be compatible with the O= option
579LINUXINCLUDE    := \
580		-I$(srctree)/arch/$(SRCARCH)/include \
581		-I$(objtree)/arch/$(SRCARCH)/include/generated \
582		-I$(srctree)/include \
583		-I$(objtree)/include \
584		$(USERINCLUDE)
585
586KBUILD_AFLAGS   := -D__ASSEMBLY__ -fno-PIE
587
588KBUILD_CFLAGS :=
589KBUILD_CFLAGS += -std=gnu11
590KBUILD_CFLAGS += -fshort-wchar
591KBUILD_CFLAGS += -funsigned-char
592KBUILD_CFLAGS += -fno-common
593KBUILD_CFLAGS += -fno-PIE
594KBUILD_CFLAGS += -fno-strict-aliasing
595
596KBUILD_CPPFLAGS := -D__KERNEL__
597KBUILD_RUSTFLAGS := $(rust_common_flags) \
598		    -Cpanic=abort -Cembed-bitcode=n -Clto=n \
599		    -Cforce-unwind-tables=n -Ccodegen-units=1 \
600		    -Csymbol-mangling-version=v0 \
601		    -Crelocation-model=static \
602		    -Zfunction-sections=n \
603		    -Wclippy::float_arithmetic
604
605KBUILD_AFLAGS_KERNEL :=
606KBUILD_CFLAGS_KERNEL :=
607KBUILD_RUSTFLAGS_KERNEL :=
608KBUILD_AFLAGS_MODULE  := -DMODULE
609KBUILD_CFLAGS_MODULE  := -DMODULE
610KBUILD_RUSTFLAGS_MODULE := --cfg MODULE
611KBUILD_LDFLAGS_MODULE :=
612KBUILD_LDFLAGS :=
613CLANG_FLAGS :=
614
615ifeq ($(KBUILD_CLIPPY),1)
616	RUSTC_OR_CLIPPY_QUIET := CLIPPY
617	RUSTC_OR_CLIPPY = $(CLIPPY_DRIVER)
618else
619	RUSTC_OR_CLIPPY_QUIET := RUSTC
620	RUSTC_OR_CLIPPY = $(RUSTC)
621endif
622
623# Allows the usage of unstable features in stable compilers.
624export RUSTC_BOOTSTRAP := 1
625
626# Allows finding `.clippy.toml` in out-of-srctree builds.
627export CLIPPY_CONF_DIR := $(srctree)
628
629export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC HOSTPKG_CONFIG
630export RUSTC RUSTDOC RUSTFMT RUSTC_OR_CLIPPY_QUIET RUSTC_OR_CLIPPY BINDGEN
631export HOSTRUSTC KBUILD_HOSTRUSTFLAGS
632export CPP AR NM STRIP OBJCOPY OBJDUMP READELF PAHOLE RESOLVE_BTFIDS LEX YACC AWK INSTALLKERNEL
633export PERL PYTHON3 CHECK CHECKFLAGS MAKE UTS_MACHINE HOSTCXX
634export KGZIP KBZIP2 KLZOP LZMA LZ4 XZ ZSTD TAR
635export KBUILD_HOSTCXXFLAGS KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS KBUILD_PROCMACROLDFLAGS LDFLAGS_MODULE
636export KBUILD_USERCFLAGS KBUILD_USERLDFLAGS
637
638export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS KBUILD_LDFLAGS
639export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
640export KBUILD_RUSTFLAGS RUSTFLAGS_KERNEL RUSTFLAGS_MODULE
641export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
642export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_RUSTFLAGS_MODULE KBUILD_LDFLAGS_MODULE
643export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL KBUILD_RUSTFLAGS_KERNEL
644
645# Files to ignore in find ... statements
646
647export RCS_FIND_IGNORE := \( -name SCCS -o -name BitKeeper -o -name .svn -o    \
648			  -name CVS -o -name .pc -o -name .hg -o -name .git \) \
649			  -prune -o
650
651# ===========================================================================
652# Rules shared between *config targets and build targets
653
654# Basic helpers built in scripts/basic/
655PHONY += scripts_basic
656scripts_basic:
657	$(Q)$(MAKE) $(build)=scripts/basic
658
659PHONY += outputmakefile
660ifdef building_out_of_srctree
661# Before starting out-of-tree build, make sure the source tree is clean.
662# outputmakefile generates a Makefile in the output directory, if using a
663# separate output directory. This allows convenient use of make in the
664# output directory.
665# At the same time when output Makefile generated, generate .gitignore to
666# ignore whole output directory
667
668ifdef KBUILD_EXTMOD
669print_env_for_makefile = \
670	echo "export KBUILD_OUTPUT = $(objtree)"; \
671	echo "export KBUILD_EXTMOD = $(realpath $(srcroot))" ; \
672	echo "export KBUILD_EXTMOD_OUTPUT = $(CURDIR)"
673else
674print_env_for_makefile = \
675	echo "export KBUILD_OUTPUT = $(CURDIR)"
676endif
677
678quiet_cmd_makefile = GEN     Makefile
679      cmd_makefile = { \
680	echo "\# Automatically generated by $(abs_srctree)/Makefile: don't edit"; \
681	$(print_env_for_makefile); \
682	echo "include $(abs_srctree)/Makefile"; \
683	} > Makefile
684
685outputmakefile:
686ifeq ($(KBUILD_EXTMOD),)
687	@if [ -f $(srctree)/.config -o \
688		 -d $(srctree)/include/config -o \
689		 -d $(srctree)/arch/$(SRCARCH)/include/generated ]; then \
690		echo >&2 "***"; \
691		echo >&2 "*** The source tree is not clean, please run 'make$(if $(findstring command line, $(origin ARCH)), ARCH=$(ARCH)) mrproper'"; \
692		echo >&2 "*** in $(abs_srctree)";\
693		echo >&2 "***"; \
694		false; \
695	fi
696else
697	@if [ -f $(srcroot)/modules.order ]; then \
698		echo >&2 "***"; \
699		echo >&2 "*** The external module source tree is not clean."; \
700		echo >&2 "*** Please run 'make -C $(abs_srctree) M=$(realpath $(srcroot)) clean'"; \
701		echo >&2 "***"; \
702		false; \
703	fi
704endif
705	$(Q)ln -fsn $(srcroot) source
706	$(call cmd,makefile)
707	$(Q)test -e .gitignore || \
708	{ echo "# this is build directory, ignore it"; echo "*"; } > .gitignore
709endif
710
711# The expansion should be delayed until arch/$(SRCARCH)/Makefile is included.
712# Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile.
713# CC_VERSION_TEXT and RUSTC_VERSION_TEXT are referenced from Kconfig (so they
714# need export), and from include/config/auto.conf.cmd to detect the compiler
715# upgrade.
716CC_VERSION_TEXT = $(subst $(pound),,$(shell LC_ALL=C $(CC) --version 2>/dev/null | head -n 1))
717RUSTC_VERSION_TEXT = $(subst $(pound),,$(shell $(RUSTC) --version 2>/dev/null))
718
719ifneq ($(findstring clang,$(CC_VERSION_TEXT)),)
720include $(srctree)/scripts/Makefile.clang
721endif
722
723# Include this also for config targets because some architectures need
724# cc-cross-prefix to determine CROSS_COMPILE.
725ifdef need-compiler
726include $(srctree)/scripts/Makefile.compiler
727endif
728
729ifdef config-build
730# ===========================================================================
731# *config targets only - make sure prerequisites are updated, and descend
732# in scripts/kconfig to make the *config target
733
734# Read arch-specific Makefile to set KBUILD_DEFCONFIG as needed.
735# KBUILD_DEFCONFIG may point out an alternative default configuration
736# used for 'make defconfig'
737include $(srctree)/arch/$(SRCARCH)/Makefile
738export KBUILD_DEFCONFIG KBUILD_KCONFIG CC_VERSION_TEXT RUSTC_VERSION_TEXT
739
740config: outputmakefile scripts_basic FORCE
741	$(Q)$(MAKE) $(build)=scripts/kconfig $@
742
743%config: outputmakefile scripts_basic FORCE
744	$(Q)$(MAKE) $(build)=scripts/kconfig $@
745
746else #!config-build
747# ===========================================================================
748# Build targets only - this includes vmlinux, arch-specific targets, clean
749# targets and others. In general all targets except *config targets.
750
751# If building an external module we do not care about the all: rule
752# but instead __all depend on modules
753PHONY += all
754ifeq ($(KBUILD_EXTMOD),)
755__all: all
756else
757__all: modules
758endif
759
760targets :=
761
762# Decide whether to build built-in, modular, or both.
763# Normally, just do built-in.
764
765KBUILD_MODULES :=
766KBUILD_BUILTIN := y
767
768# If we have only "make modules", don't compile built-in objects.
769ifeq ($(MAKECMDGOALS),modules)
770  KBUILD_BUILTIN :=
771endif
772
773# If we have "make <whatever> modules", compile modules
774# in addition to whatever we do anyway.
775# Just "make" or "make all" shall build modules as well
776
777ifneq ($(filter all modules nsdeps compile_commands.json clang-%,$(MAKECMDGOALS)),)
778  KBUILD_MODULES := y
779endif
780
781ifeq ($(MAKECMDGOALS),)
782  KBUILD_MODULES := y
783endif
784
785export KBUILD_MODULES KBUILD_BUILTIN
786
787ifdef need-config
788include $(objtree)/include/config/auto.conf
789endif
790
791ifeq ($(KBUILD_EXTMOD),)
792# Objects we will link into vmlinux / subdirs we need to visit
793core-y		:=
794drivers-y	:=
795libs-y		:= lib/
796endif # KBUILD_EXTMOD
797
798# The all: target is the default when no target is given on the
799# command line.
800# This allow a user to issue only 'make' to build a kernel including modules
801# Defaults to vmlinux, but the arch makefile usually adds further targets
802all: vmlinux
803
804CFLAGS_GCOV	:= -fprofile-arcs -ftest-coverage
805ifdef CONFIG_CC_IS_GCC
806CFLAGS_GCOV	+= -fno-tree-loop-im
807endif
808export CFLAGS_GCOV
809
810# The arch Makefiles can override CC_FLAGS_FTRACE. We may also append it later.
811ifdef CONFIG_FUNCTION_TRACER
812  CC_FLAGS_FTRACE := -pg
813endif
814
815ifdef CONFIG_TRACEPOINTS
816# To check for unused tracepoints (tracepoints that are defined but never
817# called), run with:
818#
819# make UT=1
820#
821# Each unused tracepoints can take up to 5KB of memory in the running kernel.
822# It is best to remove any that are not used.
823#
824# This command line option will be removed when all current unused
825# tracepoints are removed.
826
827ifeq ("$(origin UT)", "command line")
828  WARN_ON_UNUSED_TRACEPOINTS := $(UT)
829endif
830endif # CONFIG_TRACEPOINTS
831
832export WARN_ON_UNUSED_TRACEPOINTS
833
834include $(srctree)/arch/$(SRCARCH)/Makefile
835
836ifdef need-config
837ifdef may-sync-config
838# Read in dependencies to all Kconfig* files, make sure to run syncconfig if
839# changes are detected. This should be included after arch/$(SRCARCH)/Makefile
840# because some architectures define CROSS_COMPILE there.
841include include/config/auto.conf.cmd
842
843$(KCONFIG_CONFIG):
844	@echo >&2 '***'
845	@echo >&2 '*** Configuration file "$@" not found!'
846	@echo >&2 '***'
847	@echo >&2 '*** Please run some configurator (e.g. "make oldconfig" or'
848	@echo >&2 '*** "make menuconfig" or "make xconfig").'
849	@echo >&2 '***'
850	@/bin/false
851
852# The actual configuration files used during the build are stored in
853# include/generated/ and include/config/. Update them if .config is newer than
854# include/config/auto.conf (which mirrors .config).
855#
856# This exploits the 'multi-target pattern rule' trick.
857# The syncconfig should be executed only once to make all the targets.
858# (Note: use the grouped target '&:' when we bump to GNU Make 4.3)
859#
860# Do not use $(call cmd,...) here. That would suppress prompts from syncconfig,
861# so you cannot notice that Kconfig is waiting for the user input.
862%/config/auto.conf %/config/auto.conf.cmd %/generated/autoconf.h %/generated/rustc_cfg: $(KCONFIG_CONFIG)
863	$(Q)$(kecho) "  SYNC    $@"
864	$(Q)$(MAKE) -f $(srctree)/Makefile syncconfig
865else # !may-sync-config
866# External modules and some install targets need include/generated/autoconf.h
867# and include/config/auto.conf but do not care if they are up-to-date.
868# Use auto.conf to show the error message
869
870checked-configs := $(addprefix $(objtree)/, include/generated/autoconf.h include/generated/rustc_cfg include/config/auto.conf)
871missing-configs := $(filter-out $(wildcard $(checked-configs)), $(checked-configs))
872
873ifdef missing-configs
874PHONY += $(objtree)/include/config/auto.conf
875
876$(objtree)/include/config/auto.conf:
877	@echo   >&2 '***'
878	@echo   >&2 '***  ERROR: Kernel configuration is invalid. The following files are missing:'
879	@printf >&2 '***    - %s\n' $(missing-configs)
880	@echo   >&2 '***  Run "make oldconfig && make prepare" on kernel source to fix it.'
881	@echo   >&2 '***'
882	@/bin/false
883endif
884
885endif # may-sync-config
886endif # need-config
887
888KBUILD_CFLAGS	+= -fno-delete-null-pointer-checks
889
890ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
891KBUILD_CFLAGS += -O2
892KBUILD_RUSTFLAGS += -Copt-level=2
893else ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
894KBUILD_CFLAGS += -Os
895KBUILD_RUSTFLAGS += -Copt-level=s
896endif
897
898# Always set `debug-assertions` and `overflow-checks` because their default
899# depends on `opt-level` and `debug-assertions`, respectively.
900KBUILD_RUSTFLAGS += -Cdebug-assertions=$(if $(CONFIG_RUST_DEBUG_ASSERTIONS),y,n)
901KBUILD_RUSTFLAGS += -Coverflow-checks=$(if $(CONFIG_RUST_OVERFLOW_CHECKS),y,n)
902
903# Tell gcc to never replace conditional load with a non-conditional one
904ifdef CONFIG_CC_IS_GCC
905# gcc-10 renamed --param=allow-store-data-races=0 to
906# -fno-allow-store-data-races.
907KBUILD_CFLAGS	+= $(call cc-option,--param=allow-store-data-races=0)
908KBUILD_CFLAGS	+= $(call cc-option,-fno-allow-store-data-races)
909endif
910
911ifdef CONFIG_READABLE_ASM
912# Disable optimizations that make assembler listings hard to read.
913# reorder blocks reorders the control in the function
914# ipa clone creates specialized cloned functions
915# partial inlining inlines only parts of functions
916KBUILD_CFLAGS += -fno-reorder-blocks -fno-ipa-cp-clone -fno-partial-inlining
917endif
918
919stackp-flags-y                                    := -fno-stack-protector
920stackp-flags-$(CONFIG_STACKPROTECTOR)             := -fstack-protector
921stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG)      := -fstack-protector-strong
922
923KBUILD_CFLAGS += $(stackp-flags-y)
924
925ifdef CONFIG_FRAME_POINTER
926KBUILD_CFLAGS	+= -fno-omit-frame-pointer -fno-optimize-sibling-calls
927KBUILD_RUSTFLAGS += -Cforce-frame-pointers=y
928else
929# Some targets (ARM with Thumb2, for example), can't be built with frame
930# pointers.  For those, we don't have FUNCTION_TRACER automatically
931# select FRAME_POINTER.  However, FUNCTION_TRACER adds -pg, and this is
932# incompatible with -fomit-frame-pointer with current GCC, so we don't use
933# -fomit-frame-pointer with FUNCTION_TRACER.
934# In the Rust target specification, "frame-pointer" is set explicitly
935# to "may-omit".
936ifndef CONFIG_FUNCTION_TRACER
937KBUILD_CFLAGS	+= -fomit-frame-pointer
938endif
939endif
940
941# Initialize all stack variables with a 0xAA pattern.
942ifdef CONFIG_INIT_STACK_ALL_PATTERN
943KBUILD_CFLAGS	+= -ftrivial-auto-var-init=pattern
944endif
945
946# Initialize all stack variables with a zero value.
947ifdef CONFIG_INIT_STACK_ALL_ZERO
948KBUILD_CFLAGS	+= -ftrivial-auto-var-init=zero
949ifdef CONFIG_CC_HAS_AUTO_VAR_INIT_ZERO_ENABLER
950# https://github.com/llvm/llvm-project/issues/44842
951CC_AUTO_VAR_INIT_ZERO_ENABLER := -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
952export CC_AUTO_VAR_INIT_ZERO_ENABLER
953KBUILD_CFLAGS	+= $(CC_AUTO_VAR_INIT_ZERO_ENABLER)
954endif
955endif
956
957# Explicitly clear padding bits during variable initialization
958KBUILD_CFLAGS += $(call cc-option,-fzero-init-padding-bits=all)
959
960# While VLAs have been removed, GCC produces unreachable stack probes
961# for the randomize_kstack_offset feature. Disable it for all compilers.
962KBUILD_CFLAGS	+= $(call cc-option, -fno-stack-clash-protection)
963
964# Get details on warnings generated due to GCC value tracking.
965KBUILD_CFLAGS	+= $(call cc-option, -fdiagnostics-show-context=2)
966
967# Clear used registers at func exit (to reduce data lifetime and ROP gadgets).
968ifdef CONFIG_ZERO_CALL_USED_REGS
969KBUILD_CFLAGS	+= -fzero-call-used-regs=used-gpr
970endif
971
972ifdef CONFIG_FUNCTION_TRACER
973ifdef CONFIG_FTRACE_MCOUNT_USE_CC
974  CC_FLAGS_FTRACE	+= -mrecord-mcount
975  ifdef CONFIG_HAVE_NOP_MCOUNT
976    ifeq ($(call cc-option-yn, -mnop-mcount),y)
977      CC_FLAGS_FTRACE	+= -mnop-mcount
978      CC_FLAGS_USING	+= -DCC_USING_NOP_MCOUNT
979    endif
980  endif
981endif
982ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
983  ifdef CONFIG_HAVE_OBJTOOL_NOP_MCOUNT
984    CC_FLAGS_USING	+= -DCC_USING_NOP_MCOUNT
985  endif
986endif
987ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
988  ifdef CONFIG_HAVE_C_RECORDMCOUNT
989    BUILD_C_RECORDMCOUNT := y
990    export BUILD_C_RECORDMCOUNT
991  endif
992endif
993ifdef CONFIG_HAVE_FENTRY
994  # s390-linux-gnu-gcc did not support -mfentry until gcc-9.
995  ifeq ($(call cc-option-yn, -mfentry),y)
996    CC_FLAGS_FTRACE	+= -mfentry
997    CC_FLAGS_USING	+= -DCC_USING_FENTRY
998  endif
999endif
1000export CC_FLAGS_FTRACE
1001KBUILD_CFLAGS	+= $(CC_FLAGS_FTRACE) $(CC_FLAGS_USING)
1002KBUILD_AFLAGS	+= $(CC_FLAGS_USING)
1003endif
1004
1005# We trigger additional mismatches with less inlining
1006ifdef CONFIG_DEBUG_SECTION_MISMATCH
1007KBUILD_CFLAGS += -fno-inline-functions-called-once
1008endif
1009
1010# `rustc`'s `-Zfunction-sections` applies to data too (as of 1.59.0).
1011ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
1012KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections
1013KBUILD_RUSTFLAGS_KERNEL += -Zfunction-sections=y
1014LDFLAGS_vmlinux += --gc-sections
1015endif
1016
1017ifdef CONFIG_SHADOW_CALL_STACK
1018ifndef CONFIG_DYNAMIC_SCS
1019CC_FLAGS_SCS	:= -fsanitize=shadow-call-stack
1020KBUILD_CFLAGS	+= $(CC_FLAGS_SCS)
1021KBUILD_RUSTFLAGS += -Zsanitizer=shadow-call-stack
1022endif
1023export CC_FLAGS_SCS
1024endif
1025
1026ifdef CONFIG_LTO_CLANG
1027ifdef CONFIG_LTO_CLANG_THIN
1028CC_FLAGS_LTO	:= -flto=thin -fsplit-lto-unit
1029else
1030CC_FLAGS_LTO	:= -flto
1031endif
1032CC_FLAGS_LTO	+= -fvisibility=hidden
1033
1034# Limit inlining across translation units to reduce binary size
1035KBUILD_LDFLAGS += -mllvm -import-instr-limit=5
1036endif
1037
1038ifdef CONFIG_LTO
1039KBUILD_CFLAGS	+= -fno-lto $(CC_FLAGS_LTO)
1040KBUILD_AFLAGS	+= -fno-lto
1041export CC_FLAGS_LTO
1042endif
1043
1044ifdef CONFIG_CFI
1045CC_FLAGS_CFI	:= -fsanitize=kcfi
1046ifdef CONFIG_CFI_ICALL_NORMALIZE_INTEGERS
1047	CC_FLAGS_CFI	+= -fsanitize-cfi-icall-experimental-normalize-integers
1048endif
1049ifdef CONFIG_FINEIBT_BHI
1050	CC_FLAGS_CFI	+= -fsanitize-kcfi-arity
1051endif
1052ifdef CONFIG_RUST
1053	# Always pass -Zsanitizer-cfi-normalize-integers as CONFIG_RUST selects
1054	# CONFIG_CFI_ICALL_NORMALIZE_INTEGERS.
1055	RUSTC_FLAGS_CFI   := -Zsanitizer=kcfi -Zsanitizer-cfi-normalize-integers
1056	KBUILD_RUSTFLAGS += $(RUSTC_FLAGS_CFI)
1057	export RUSTC_FLAGS_CFI
1058endif
1059KBUILD_CFLAGS	+= $(CC_FLAGS_CFI)
1060export CC_FLAGS_CFI
1061endif
1062
1063# Architectures can define flags to add/remove for floating-point support
1064CC_FLAGS_FPU	+= -D_LINUX_FPU_COMPILATION_UNIT
1065export CC_FLAGS_FPU
1066export CC_FLAGS_NO_FPU
1067
1068ifneq ($(CONFIG_FUNCTION_ALIGNMENT),0)
1069# Set the minimal function alignment. Use the newer GCC option
1070# -fmin-function-alignment if it is available, or fall back to -falign-funtions.
1071# See also CONFIG_CC_HAS_SANE_FUNCTION_ALIGNMENT.
1072ifdef CONFIG_CC_HAS_MIN_FUNCTION_ALIGNMENT
1073KBUILD_CFLAGS += -fmin-function-alignment=$(CONFIG_FUNCTION_ALIGNMENT)
1074else
1075KBUILD_CFLAGS += -falign-functions=$(CONFIG_FUNCTION_ALIGNMENT)
1076endif
1077endif
1078
1079# arch Makefile may override CC so keep this after arch Makefile is included
1080NOSTDINC_FLAGS += -nostdinc
1081
1082# To gain proper coverage for CONFIG_UBSAN_BOUNDS and CONFIG_FORTIFY_SOURCE,
1083# the kernel uses only C99 flexible arrays for dynamically sized trailing
1084# arrays. Enforce this for everything that may examine structure sizes and
1085# perform bounds checking.
1086KBUILD_CFLAGS += $(call cc-option, -fstrict-flex-arrays=3)
1087
1088# Allow including a tagged struct or union anonymously in another struct/union.
1089KBUILD_CFLAGS += -fms-extensions
1090
1091# disable invalid "can't wrap" optimizations for signed / pointers
1092KBUILD_CFLAGS	+= -fno-strict-overflow
1093
1094# Make sure -fstack-check isn't enabled (like gentoo apparently did)
1095KBUILD_CFLAGS  += -fno-stack-check
1096
1097# conserve stack if available
1098ifdef CONFIG_CC_IS_GCC
1099KBUILD_CFLAGS   += -fconserve-stack
1100endif
1101
1102# Ensure compilers do not transform certain loops into calls to wcslen()
1103KBUILD_CFLAGS += -fno-builtin-wcslen
1104
1105# change __FILE__ to the relative path to the source directory
1106ifdef building_out_of_srctree
1107KBUILD_CPPFLAGS += -fmacro-prefix-map=$(srcroot)/=
1108endif
1109
1110# include additional Makefiles when needed
1111include-y			:= scripts/Makefile.warn
1112include-$(CONFIG_DEBUG_INFO)	+= scripts/Makefile.debug
1113include-$(CONFIG_DEBUG_INFO_BTF)+= scripts/Makefile.btf
1114include-$(CONFIG_KASAN)		+= scripts/Makefile.kasan
1115include-$(CONFIG_KCSAN)		+= scripts/Makefile.kcsan
1116include-$(CONFIG_KMSAN)		+= scripts/Makefile.kmsan
1117include-$(CONFIG_UBSAN)		+= scripts/Makefile.ubsan
1118include-$(CONFIG_KCOV)		+= scripts/Makefile.kcov
1119include-$(CONFIG_RANDSTRUCT)	+= scripts/Makefile.randstruct
1120include-$(CONFIG_KSTACK_ERASE)	+= scripts/Makefile.kstack_erase
1121include-$(CONFIG_AUTOFDO_CLANG)	+= scripts/Makefile.autofdo
1122include-$(CONFIG_PROPELLER_CLANG)	+= scripts/Makefile.propeller
1123include-$(CONFIG_GCC_PLUGINS)	+= scripts/Makefile.gcc-plugins
1124
1125include $(addprefix $(srctree)/, $(include-y))
1126
1127# scripts/Makefile.gcc-plugins is intentionally included last.
1128# Do not add $(call cc-option,...) below this line. When you build the kernel
1129# from the clean source tree, the GCC plugins do not exist at this point.
1130
1131# Add user supplied CPPFLAGS, AFLAGS, CFLAGS and RUSTFLAGS as the last assignments
1132KBUILD_CPPFLAGS += $(KCPPFLAGS)
1133KBUILD_AFLAGS   += $(KAFLAGS)
1134KBUILD_CFLAGS   += $(KCFLAGS)
1135KBUILD_RUSTFLAGS += $(KRUSTFLAGS)
1136
1137KBUILD_LDFLAGS_MODULE += --build-id=sha1
1138LDFLAGS_vmlinux += --build-id=sha1
1139
1140KBUILD_LDFLAGS	+= -z noexecstack
1141ifeq ($(CONFIG_LD_IS_BFD),y)
1142KBUILD_LDFLAGS	+= $(call ld-option,--no-warn-rwx-segments)
1143endif
1144
1145ifeq ($(CONFIG_STRIP_ASM_SYMS),y)
1146LDFLAGS_vmlinux	+= -X
1147endif
1148
1149ifeq ($(CONFIG_RELR),y)
1150# ld.lld before 15 did not support -z pack-relative-relocs.
1151LDFLAGS_vmlinux	+= $(call ld-option,--pack-dyn-relocs=relr,-z pack-relative-relocs)
1152endif
1153
1154# We never want expected sections to be placed heuristically by the
1155# linker. All sections should be explicitly named in the linker script.
1156ifdef CONFIG_LD_ORPHAN_WARN
1157LDFLAGS_vmlinux += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
1158endif
1159
1160ifneq ($(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS),)
1161LDFLAGS_vmlinux	+= --emit-relocs --discard-none
1162endif
1163
1164# Align the architecture of userspace programs with the kernel
1165USERFLAGS_FROM_KERNEL := --target=%
1166
1167ifdef CONFIG_ARCH_USERFLAGS
1168KBUILD_USERCFLAGS += $(CONFIG_ARCH_USERFLAGS)
1169KBUILD_USERLDFLAGS += $(CONFIG_ARCH_USERFLAGS)
1170else
1171# If not overridden also inherit the bit size
1172USERFLAGS_FROM_KERNEL += -m32 -m64
1173endif
1174
1175KBUILD_USERCFLAGS  += $(filter $(USERFLAGS_FROM_KERNEL), $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
1176KBUILD_USERLDFLAGS += $(filter $(USERFLAGS_FROM_KERNEL), $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
1177
1178# userspace programs are linked via the compiler, use the correct linker
1179ifdef CONFIG_CC_IS_CLANG
1180KBUILD_USERLDFLAGS += --ld-path=$(LD)
1181endif
1182
1183# make the checker run with the right architecture
1184CHECKFLAGS += --arch=$(ARCH)
1185
1186# insure the checker run with the right endianness
1187CHECKFLAGS += $(if $(CONFIG_CPU_BIG_ENDIAN),-mbig-endian,-mlittle-endian)
1188
1189# the checker needs the correct machine size
1190CHECKFLAGS += $(if $(CONFIG_64BIT),-m64,-m32)
1191
1192# Default kernel image to build when no specific target is given.
1193# KBUILD_IMAGE may be overruled on the command line or
1194# set in the environment
1195# Also any assignments in arch/$(ARCH)/Makefile take precedence over
1196# this default value
1197export KBUILD_IMAGE ?= vmlinux
1198
1199#
1200# INSTALL_PATH specifies where to place the updated kernel and system map
1201# images. Default is /boot, but you can set it to other values
1202export	INSTALL_PATH ?= /boot
1203
1204#
1205# INSTALL_DTBS_PATH specifies a prefix for relocations required by build roots.
1206# Like INSTALL_MOD_PATH, it isn't defined in the Makefile, but can be passed as
1207# an argument if needed. Otherwise it defaults to the kernel install path
1208#
1209export INSTALL_DTBS_PATH ?= $(INSTALL_PATH)/dtbs/$(KERNELRELEASE)
1210
1211#
1212# INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
1213# relocations required by build roots.  This is not defined in the
1214# makefile but the argument can be passed to make if needed.
1215#
1216
1217MODLIB	= $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
1218export MODLIB
1219
1220PHONY += prepare0
1221
1222ifeq ($(KBUILD_EXTMOD),)
1223
1224build-dir	:= .
1225clean-dirs	:= $(sort . Documentation \
1226		     $(patsubst %/,%,$(filter %/, $(core-) \
1227			$(drivers-) $(libs-))))
1228
1229export ARCH_CORE	:= $(core-y)
1230export ARCH_LIB		:= $(filter %/, $(libs-y))
1231export ARCH_DRIVERS	:= $(drivers-y) $(drivers-m)
1232# Externally visible symbols (used by link-vmlinux.sh)
1233
1234KBUILD_VMLINUX_OBJS := built-in.a $(patsubst %/, %/lib.a, $(filter %/, $(libs-y)))
1235KBUILD_VMLINUX_LIBS := $(filter-out %/, $(libs-y))
1236
1237export KBUILD_VMLINUX_LIBS
1238export KBUILD_LDS          := arch/$(SRCARCH)/kernel/vmlinux.lds
1239
1240ifdef CONFIG_TRIM_UNUSED_KSYMS
1241# For the kernel to actually contain only the needed exported symbols,
1242# we have to build modules as well to determine what those symbols are.
1243KBUILD_MODULES := y
1244endif
1245
1246# '$(AR) mPi' needs 'T' to workaround the bug of llvm-ar <= 14
1247quiet_cmd_ar_vmlinux.a = AR      $@
1248      cmd_ar_vmlinux.a = \
1249	rm -f $@; \
1250	$(AR) cDPrST $@ $(KBUILD_VMLINUX_OBJS); \
1251	$(AR) mPiT $$($(AR) t $@ | sed -n 1p) $@ $$($(AR) t $@ | grep -F -f $(srctree)/scripts/head-object-list.txt)
1252
1253targets += vmlinux.a
1254vmlinux.a: $(KBUILD_VMLINUX_OBJS) scripts/head-object-list.txt FORCE
1255	$(call if_changed,ar_vmlinux.a)
1256
1257PHONY += vmlinux_o
1258vmlinux_o: vmlinux.a $(KBUILD_VMLINUX_LIBS)
1259	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.vmlinux_o
1260
1261vmlinux.o modules.builtin.modinfo modules.builtin: vmlinux_o
1262	@:
1263
1264PHONY += vmlinux
1265# LDFLAGS_vmlinux in the top Makefile defines linker flags for the top vmlinux,
1266# not for decompressors. LDFLAGS_vmlinux in arch/*/boot/compressed/Makefile is
1267# unrelated; the decompressors just happen to have the same base name,
1268# arch/*/boot/compressed/vmlinux.
1269# Export LDFLAGS_vmlinux only to scripts/Makefile.vmlinux.
1270#
1271# _LDFLAGS_vmlinux is a workaround for the 'private export' bug:
1272#   https://savannah.gnu.org/bugs/?61463
1273# For Make > 4.4, the following simple code will work:
1274#  vmlinux: private export LDFLAGS_vmlinux := $(LDFLAGS_vmlinux)
1275vmlinux: private _LDFLAGS_vmlinux := $(LDFLAGS_vmlinux)
1276vmlinux: export LDFLAGS_vmlinux = $(_LDFLAGS_vmlinux)
1277vmlinux: vmlinux.o $(KBUILD_LDS) modpost
1278	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.vmlinux
1279
1280# The actual objects are generated when descending,
1281# make sure no implicit rule kicks in
1282$(sort $(KBUILD_LDS) $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)): . ;
1283
1284ifeq ($(origin KERNELRELEASE),file)
1285filechk_kernel.release = $(srctree)/scripts/setlocalversion $(srctree)
1286else
1287filechk_kernel.release = echo $(KERNELRELEASE)
1288endif
1289
1290# Store (new) KERNELRELEASE string in include/config/kernel.release
1291include/config/kernel.release: FORCE
1292	$(call filechk,kernel.release)
1293
1294# Additional helpers built in scripts/
1295# Carefully list dependencies so we do not try to build scripts twice
1296# in parallel
1297PHONY += scripts
1298scripts: scripts_basic scripts_dtc
1299	$(Q)$(MAKE) $(build)=$(@)
1300
1301# Things we need to do before we recursively start building the kernel
1302# or the modules are listed in "prepare".
1303# A multi level approach is used. prepareN is processed before prepareN-1.
1304# archprepare is used in arch Makefiles and when processed asm symlink,
1305# version.h and scripts_basic is processed / created.
1306
1307PHONY += prepare archprepare
1308
1309archprepare: outputmakefile archheaders archscripts scripts include/config/kernel.release \
1310	asm-generic $(version_h) include/generated/utsrelease.h \
1311	include/generated/compile.h include/generated/autoconf.h \
1312	include/generated/rustc_cfg remove-stale-files
1313
1314prepare0: archprepare
1315	$(Q)$(MAKE) $(build)=scripts/mod
1316	$(Q)$(MAKE) $(build)=. prepare
1317
1318# All the preparing..
1319prepare: prepare0
1320ifdef CONFIG_RUST
1321	+$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh
1322	$(Q)$(MAKE) $(build)=rust
1323endif
1324
1325PHONY += remove-stale-files
1326remove-stale-files:
1327	$(Q)$(srctree)/scripts/remove-stale-files
1328
1329# Support for using generic headers in asm-generic
1330asm-generic := -f $(srctree)/scripts/Makefile.asm-headers obj
1331
1332PHONY += asm-generic uapi-asm-generic
1333asm-generic: uapi-asm-generic
1334	$(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/asm \
1335	generic=include/asm-generic
1336uapi-asm-generic:
1337	$(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/uapi/asm \
1338	generic=include/uapi/asm-generic
1339
1340# Generate some files
1341# ---------------------------------------------------------------------------
1342
1343# KERNELRELEASE can change from a few different places, meaning version.h
1344# needs to be updated, so this check is forced on all builds
1345
1346uts_len := 64
1347define filechk_utsrelease.h
1348	if [ `echo -n "$(KERNELRELEASE)" | wc -c ` -gt $(uts_len) ]; then \
1349	  echo '"$(KERNELRELEASE)" exceeds $(uts_len) characters' >&2;    \
1350	  exit 1;                                                         \
1351	fi;                                                               \
1352	echo \#define UTS_RELEASE \"$(KERNELRELEASE)\"
1353endef
1354
1355define filechk_version.h
1356	if [ $(SUBLEVEL) -gt 255 ]; then                                 \
1357		echo \#define LINUX_VERSION_CODE $(shell                 \
1358		expr $(VERSION) \* 65536 + $(PATCHLEVEL) \* 256 + 255); \
1359	else                                                             \
1360		echo \#define LINUX_VERSION_CODE $(shell                 \
1361		expr $(VERSION) \* 65536 + $(PATCHLEVEL) \* 256 + $(SUBLEVEL)); \
1362	fi;                                                              \
1363	echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) +  \
1364	((c) > 255 ? 255 : (c)))';                                       \
1365	echo \#define LINUX_VERSION_MAJOR $(VERSION);                    \
1366	echo \#define LINUX_VERSION_PATCHLEVEL $(PATCHLEVEL);            \
1367	echo \#define LINUX_VERSION_SUBLEVEL $(SUBLEVEL)
1368endef
1369
1370$(version_h): private PATCHLEVEL := $(or $(PATCHLEVEL), 0)
1371$(version_h): private SUBLEVEL := $(or $(SUBLEVEL), 0)
1372$(version_h): FORCE
1373	$(call filechk,version.h)
1374
1375include/generated/utsrelease.h: include/config/kernel.release FORCE
1376	$(call filechk,utsrelease.h)
1377
1378filechk_compile.h = $(srctree)/scripts/mkcompile_h \
1379	"$(UTS_MACHINE)" "$(CONFIG_CC_VERSION_TEXT)" "$(LD)"
1380
1381include/generated/compile.h: FORCE
1382	$(call filechk,compile.h)
1383
1384PHONY += headerdep
1385headerdep:
1386	$(Q)find $(srctree)/include/ -name '*.h' | xargs --max-args 1 \
1387	$(srctree)/scripts/headerdep.pl -I$(srctree)/include
1388
1389# ---------------------------------------------------------------------------
1390# Kernel headers
1391
1392#Default location for installed headers
1393export INSTALL_HDR_PATH = $(objtree)/usr
1394
1395quiet_cmd_headers_install = INSTALL $(INSTALL_HDR_PATH)/include
1396      cmd_headers_install = \
1397	mkdir -p $(INSTALL_HDR_PATH); \
1398	rsync -mrl --include='*/' --include='*\.h' --exclude='*' \
1399	usr/include $(INSTALL_HDR_PATH)
1400
1401PHONY += headers_install
1402headers_install: headers
1403	$(call cmd,headers_install)
1404
1405PHONY += archheaders archscripts
1406
1407hdr-inst := -f $(srctree)/scripts/Makefile.headersinst obj
1408
1409PHONY += headers
1410headers: $(version_h) scripts_unifdef uapi-asm-generic archheaders
1411ifdef HEADER_ARCH
1412	$(Q)$(MAKE) -f $(srctree)/Makefile HEADER_ARCH= SRCARCH=$(HEADER_ARCH) headers
1413else
1414	$(Q)$(MAKE) $(hdr-inst)=include/uapi
1415	$(Q)$(MAKE) $(hdr-inst)=arch/$(SRCARCH)/include/uapi
1416endif
1417
1418ifdef CONFIG_HEADERS_INSTALL
1419prepare: headers
1420endif
1421
1422PHONY += usr_gen_init_cpio
1423usr_gen_init_cpio: scripts_basic
1424	$(Q)$(MAKE) $(build)=usr usr/gen_init_cpio
1425
1426PHONY += scripts_unifdef
1427scripts_unifdef: scripts_basic
1428	$(Q)$(MAKE) $(build)=scripts scripts/unifdef
1429
1430PHONY += scripts_gen_packed_field_checks
1431scripts_gen_packed_field_checks: scripts_basic
1432	$(Q)$(MAKE) $(build)=scripts scripts/gen_packed_field_checks
1433
1434# ---------------------------------------------------------------------------
1435# Install
1436
1437# Many distributions have the custom install script, /sbin/installkernel.
1438# If DKMS is installed, 'make install' will eventually recurse back
1439# to this Makefile to build and install external modules.
1440# Cancel sub_make_done so that options such as M=, V=, etc. are parsed.
1441
1442quiet_cmd_install = INSTALL $(INSTALL_PATH)
1443      cmd_install = unset sub_make_done; $(srctree)/scripts/install.sh
1444
1445# ---------------------------------------------------------------------------
1446# vDSO install
1447
1448PHONY += vdso_install
1449vdso_install: export INSTALL_FILES = $(vdso-install-y)
1450vdso_install:
1451	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.vdsoinst
1452
1453# ---------------------------------------------------------------------------
1454# Tools
1455
1456ifdef CONFIG_OBJTOOL
1457prepare: tools/objtool
1458endif
1459
1460ifdef CONFIG_BPF
1461ifdef CONFIG_DEBUG_INFO_BTF
1462prepare: tools/bpf/resolve_btfids
1463endif
1464endif
1465
1466# The tools build system is not a part of Kbuild and tends to introduce
1467# its own unique issues. If you need to integrate a new tool into Kbuild,
1468# please consider locating that tool outside the tools/ tree and using the
1469# standard Kbuild "hostprogs" syntax instead of adding a new tools/* entry
1470# here. See Documentation/kbuild/makefiles.rst for details.
1471
1472PHONY += resolve_btfids_clean
1473
1474resolve_btfids_O = $(abspath $(objtree))/tools/bpf/resolve_btfids
1475
1476# tools/bpf/resolve_btfids directory might not exist
1477# in output directory, skip its clean in that case
1478resolve_btfids_clean:
1479ifneq ($(wildcard $(resolve_btfids_O)),)
1480	$(Q)$(MAKE) -sC $(srctree)/tools/bpf/resolve_btfids O=$(resolve_btfids_O) clean
1481endif
1482
1483tools/: FORCE
1484	$(Q)mkdir -p $(objtree)/tools
1485	$(Q)$(MAKE) O=$(abspath $(objtree)) subdir=tools -C $(srctree)/tools/
1486
1487tools/%: FORCE
1488	$(Q)mkdir -p $(objtree)/tools
1489	$(Q)$(MAKE) O=$(abspath $(objtree)) subdir=tools -C $(srctree)/tools/ $*
1490
1491# ---------------------------------------------------------------------------
1492# Kernel selftest
1493
1494PHONY += kselftest
1495kselftest: headers
1496	$(Q)$(MAKE) -C $(srctree)/tools/testing/selftests run_tests
1497
1498kselftest-%: headers FORCE
1499	$(Q)$(MAKE) -C $(srctree)/tools/testing/selftests $*
1500
1501PHONY += kselftest-merge
1502kselftest-merge:
1503	$(if $(wildcard $(objtree)/.config),, $(error No .config exists, config your kernel first!))
1504	$(Q)find $(srctree)/tools/testing/selftests -name config -o -name config.$(UTS_MACHINE) | \
1505		xargs $(srctree)/scripts/kconfig/merge_config.sh -y -m $(objtree)/.config
1506	$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
1507
1508# ---------------------------------------------------------------------------
1509# Devicetree files
1510
1511ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/boot/dts/),)
1512dtstree := arch/$(SRCARCH)/boot/dts
1513endif
1514
1515ifneq ($(dtstree),)
1516
1517%.dtb: dtbs_prepare
1518	$(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
1519
1520%.dtbo: dtbs_prepare
1521	$(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
1522
1523PHONY += dtbs dtbs_prepare dtbs_install dtbs_check
1524dtbs: dtbs_prepare
1525	$(Q)$(MAKE) $(build)=$(dtstree) need-dtbslist=1
1526
1527# include/config/kernel.release is actually needed when installing DTBs because
1528# INSTALL_DTBS_PATH contains $(KERNELRELEASE). However, we do not want to make
1529# dtbs_install depend on it as dtbs_install may run as root.
1530dtbs_prepare: include/config/kernel.release scripts_dtc
1531
1532ifneq ($(filter dtbs_check, $(MAKECMDGOALS)),)
1533export CHECK_DTBS=y
1534endif
1535
1536ifneq ($(CHECK_DTBS),)
1537dtbs_prepare: dt_binding_schemas
1538endif
1539
1540dtbs_check: dtbs
1541
1542dtbs_install:
1543	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.dtbinst obj=$(dtstree)
1544
1545ifdef CONFIG_OF_EARLY_FLATTREE
1546all: dtbs
1547endif
1548
1549ifdef CONFIG_GENERIC_BUILTIN_DTB
1550vmlinux: dtbs
1551endif
1552
1553endif
1554
1555PHONY += scripts_dtc
1556scripts_dtc: scripts_basic
1557	$(Q)$(MAKE) $(build)=scripts/dtc
1558
1559ifneq ($(filter dt_binding_check, $(MAKECMDGOALS)),)
1560export CHECK_DTBS=y
1561endif
1562
1563PHONY += dt_binding_check dt_binding_schemas
1564dt_binding_check: dt_binding_schemas scripts_dtc
1565	$(Q)$(MAKE) $(build)=Documentation/devicetree/bindings $@
1566
1567dt_binding_schemas:
1568	$(Q)$(MAKE) $(build)=Documentation/devicetree/bindings
1569
1570PHONY += dt_compatible_check
1571dt_compatible_check: dt_binding_schemas
1572	$(Q)$(MAKE) $(build)=Documentation/devicetree/bindings $@
1573
1574# ---------------------------------------------------------------------------
1575# Modules
1576
1577ifdef CONFIG_MODULES
1578
1579# By default, build modules as well
1580
1581all: modules
1582
1583# When we're building modules with modversions, we need to consider
1584# the built-in objects during the descend as well, in order to
1585# make sure the checksums are up to date before we record them.
1586ifdef CONFIG_MODVERSIONS
1587  KBUILD_BUILTIN := y
1588endif
1589
1590# Build modules
1591#
1592
1593# *.ko are usually independent of vmlinux, but CONFIG_DEBUG_INFO_BTF_MODULES
1594# is an exception.
1595ifdef CONFIG_DEBUG_INFO_BTF_MODULES
1596KBUILD_BUILTIN := y
1597modules: vmlinux
1598endif
1599
1600modules: modules_prepare
1601
1602# Target to prepare building external modules
1603modules_prepare: prepare
1604	$(Q)$(MAKE) $(build)=scripts scripts/module.lds
1605
1606endif # CONFIG_MODULES
1607
1608###
1609# Cleaning is done on three levels.
1610# make clean     Delete most generated files
1611#                Leave enough to build external modules
1612# make mrproper  Delete the current configuration, and all generated files
1613# make distclean Remove editor backup files, patch leftover files and the like
1614
1615# Directories & files removed with 'make clean'
1616CLEAN_FILES += vmlinux.symvers modules-only.symvers \
1617	       modules.builtin modules.builtin.modinfo modules.nsdeps \
1618	       modules.builtin.ranges vmlinux.o.map vmlinux.unstripped \
1619	       compile_commands.json rust/test \
1620	       rust-project.json .vmlinux.objs .vmlinux.export.c \
1621               .builtin-dtbs-list .builtin-dtb.S
1622
1623# Directories & files removed with 'make mrproper'
1624MRPROPER_FILES += include/config include/generated          \
1625		  arch/$(SRCARCH)/include/generated .objdiff \
1626		  debian snap tar-install PKGBUILD pacman \
1627		  .config .config.old .version \
1628		  Module.symvers \
1629		  certs/signing_key.pem \
1630		  certs/x509.genkey \
1631		  vmlinux-gdb.py \
1632		  rpmbuild \
1633		  rust/libmacros.so rust/libmacros.dylib
1634
1635# clean - Delete most, but leave enough to build external modules
1636#
1637clean: private rm-files := $(CLEAN_FILES)
1638
1639PHONY += archclean vmlinuxclean
1640
1641vmlinuxclean:
1642	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/link-vmlinux.sh clean
1643	$(Q)$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) clean)
1644
1645clean: archclean vmlinuxclean resolve_btfids_clean
1646
1647# mrproper - Delete all generated files, including .config
1648#
1649mrproper: private rm-files := $(MRPROPER_FILES)
1650mrproper-dirs      := $(addprefix _mrproper_,scripts)
1651
1652PHONY += $(mrproper-dirs) mrproper
1653$(mrproper-dirs):
1654	$(Q)$(MAKE) $(clean)=$(patsubst _mrproper_%,%,$@)
1655
1656mrproper: clean $(mrproper-dirs)
1657	$(call cmd,rmfiles)
1658	@find . $(RCS_FIND_IGNORE) \
1659		\( -name '*.rmeta' \) \
1660		-type f -print | xargs rm -f
1661
1662# distclean
1663#
1664PHONY += distclean
1665
1666distclean: mrproper
1667	@find . $(RCS_FIND_IGNORE) \
1668		\( -name '*.orig' -o -name '*.rej' -o -name '*~' \
1669		-o -name '*.bak' -o -name '#*#' -o -name '*%' \
1670		-o -name 'core' -o -name tags -o -name TAGS -o -name 'cscope*' \
1671		-o -name GPATH -o -name GRTAGS -o -name GSYMS -o -name GTAGS \) \
1672		-type f -print | xargs rm -f
1673
1674
1675# Packaging of the kernel to various formats
1676# ---------------------------------------------------------------------------
1677
1678modules-cpio-pkg: usr_gen_init_cpio
1679
1680%src-pkg: FORCE
1681	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.package $@
1682%pkg: include/config/kernel.release FORCE
1683	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.package $@
1684
1685# Brief documentation of the typical targets used
1686# ---------------------------------------------------------------------------
1687
1688boards := $(wildcard $(srctree)/arch/$(SRCARCH)/configs/*_defconfig)
1689boards := $(sort $(notdir $(boards)))
1690board-dirs := $(dir $(wildcard $(srctree)/arch/$(SRCARCH)/configs/*/*_defconfig))
1691board-dirs := $(sort $(notdir $(board-dirs:/=)))
1692
1693PHONY += help
1694help:
1695	@echo  'Cleaning targets:'
1696	@echo  '  clean		  - Remove most generated files but keep the config and'
1697	@echo  '                    enough build support to build external modules'
1698	@echo  '  mrproper	  - Remove all generated files + config + various backup files'
1699	@echo  '  distclean	  - mrproper + remove editor backup and patch files'
1700	@echo  ''
1701	@$(MAKE) -f $(srctree)/scripts/kconfig/Makefile help
1702	@echo  ''
1703	@echo  'Other generic targets:'
1704	@echo  '  all		  - Build all targets marked with [*]'
1705	@echo  '* vmlinux	  - Build the bare kernel'
1706	@echo  '* modules	  - Build all modules'
1707	@echo  '  modules_install - Install all modules to INSTALL_MOD_PATH (default: /)'
1708	@echo  '  vdso_install    - Install unstripped vdso to INSTALL_MOD_PATH (default: /)'
1709	@echo  '  dir/            - Build all files in dir and below'
1710	@echo  '  dir/file.[ois]  - Build specified target only'
1711	@echo  '  dir/file.ll     - Build the LLVM assembly file'
1712	@echo  '                    (requires compiler support for LLVM assembly generation)'
1713	@echo  '  dir/file.lst    - Build specified mixed source/assembly target only'
1714	@echo  '                    (requires a recent binutils and recent build (System.map))'
1715	@echo  '  dir/file.ko     - Build module including final link'
1716	@echo  '  modules_prepare - Set up for building external modules'
1717	@echo  '  tags/TAGS	  - Generate tags file for editors'
1718	@echo  '  cscope	  - Generate cscope index'
1719	@echo  '  gtags           - Generate GNU GLOBAL index'
1720	@echo  '  kernelrelease	  - Output the release version string (use with make -s)'
1721	@echo  '  kernelversion	  - Output the version stored in Makefile (use with make -s)'
1722	@echo  '  image_name	  - Output the image name (use with make -s)'
1723	@echo  '  headers	  - Build ready-to-install UAPI headers in usr/include'
1724	@echo  '  headers_install - Install sanitised kernel UAPI headers to INSTALL_HDR_PATH'; \
1725	 echo  '                    (default: $(INSTALL_HDR_PATH))'; \
1726	 echo  ''
1727	@echo  'Static analysers:'
1728	@echo  '  checkstack      - Generate a list of stack hogs and consider all functions'
1729	@echo  '                    with a stack size larger than MINSTACKSIZE (default: 100)'
1730	@echo  '  versioncheck    - Sanity check on version.h usage'
1731	@echo  '  includecheck    - Check for duplicate included header files'
1732	@echo  '  headerdep       - Detect inclusion cycles in headers'
1733	@echo  '  coccicheck      - Check with Coccinelle'
1734	@echo  '  clang-analyzer  - Check with clang static analyzer'
1735	@echo  '  clang-tidy      - Check with clang-tidy'
1736	@echo  ''
1737	@echo  'Tools:'
1738	@echo  '  nsdeps          - Generate missing symbol namespace dependencies'
1739	@echo  ''
1740	@echo  'Kernel selftest:'
1741	@echo  '  kselftest         - Build and run kernel selftest'
1742	@echo  '                      Build, install, and boot kernel before'
1743	@echo  '                      running kselftest on it'
1744	@echo  '                      Run as root for full coverage'
1745	@echo  '  kselftest-all     - Build kernel selftest'
1746	@echo  '  kselftest-install - Build and install kernel selftest'
1747	@echo  '  kselftest-clean   - Remove all generated kselftest files'
1748	@echo  '  kselftest-merge   - Merge all the config dependencies of'
1749	@echo  '		      kselftest to existing .config.'
1750	@echo  ''
1751	@echo  'Rust targets:'
1752	@echo  '  rustavailable   - Checks whether the Rust toolchain is'
1753	@echo  '		    available and, if not, explains why.'
1754	@echo  '  rustfmt	  - Reformat all the Rust code in the kernel'
1755	@echo  '  rustfmtcheck	  - Checks if all the Rust code in the kernel'
1756	@echo  '		    is formatted, printing a diff otherwise.'
1757	@echo  '  rustdoc	  - Generate Rust documentation'
1758	@echo  '		    (requires kernel .config)'
1759	@echo  '  rusttest        - Runs the Rust tests'
1760	@echo  '                    (requires kernel .config; downloads external repos)'
1761	@echo  '  rust-analyzer	  - Generate rust-project.json rust-analyzer support file'
1762	@echo  '		    (requires kernel .config)'
1763	@echo  '  dir/file.[os]   - Build specified target only'
1764	@echo  '  dir/file.rsi    - Build macro expanded source, similar to C preprocessing.'
1765	@echo  '                    Run with RUSTFMT=n to skip reformatting if needed.'
1766	@echo  '                    The output is not intended to be compilable.'
1767	@echo  '  dir/file.ll     - Build the LLVM assembly file'
1768	@echo  ''
1769	@$(if $(dtstree), \
1770		echo 'Devicetree:'; \
1771		echo '* dtbs               - Build device tree blobs for enabled boards'; \
1772		echo '  dtbs_install       - Install dtbs to $(INSTALL_DTBS_PATH)'; \
1773		echo '  dt_binding_check   - Validate device tree binding documents and examples'; \
1774		echo '  dt_binding_schemas - Build processed device tree binding schemas'; \
1775		echo '  dtbs_check         - Validate device tree source files';\
1776		echo '')
1777
1778	@echo 'Userspace tools targets:'
1779	@echo '  use "make tools/help"'
1780	@echo '  or  "cd tools; make help"'
1781	@echo  ''
1782	@echo  'Kernel packaging:'
1783	@$(MAKE) -f $(srctree)/scripts/Makefile.package help
1784	@echo  ''
1785	@echo  'Documentation targets:'
1786	@$(MAKE) -f $(srctree)/Documentation/Makefile dochelp
1787	@echo  ''
1788	@echo  'Architecture-specific targets ($(SRCARCH)):'
1789	@$(or $(archhelp),\
1790		echo '  No architecture-specific help defined for $(SRCARCH)')
1791	@echo  ''
1792	@$(if $(boards), \
1793		$(foreach b, $(boards), \
1794		printf "  %-27s - Build for %s\\n" $(b) $(subst _defconfig,,$(b));) \
1795		echo '')
1796	@$(if $(board-dirs), \
1797		$(foreach b, $(board-dirs), \
1798		printf "  %-16s - Show %s-specific targets\\n" help-$(b) $(b);) \
1799		printf "  %-16s - Show all of the above\\n" help-boards; \
1800		echo '')
1801
1802	@echo  '  make V=n   [targets] 1: verbose build'
1803	@echo  '                       2: give reason for rebuild of target'
1804	@echo  '                       V=1 and V=2 can be combined with V=12'
1805	@echo  '  make O=dir [targets] Locate all output files in "dir", including .config'
1806	@echo  '  make C=1   [targets] Check re-compiled c source with $$CHECK'
1807	@echo  '                       (sparse by default)'
1808	@echo  '  make C=2   [targets] Force check of all c source with $$CHECK'
1809	@echo  '  make RECORDMCOUNT_WARN=1 [targets] Warn about ignored mcount sections'
1810	@echo  '  make W=n   [targets] Enable extra build checks, n=1,2,3,c,e where'
1811	@echo  '		1: warnings which may be relevant and do not occur too often'
1812	@echo  '		2: warnings which occur quite often but may still be relevant'
1813	@echo  '		3: more obscure warnings, can most likely be ignored'
1814	@echo  '		c: extra checks in the configuration stage (Kconfig)'
1815	@echo  '		e: warnings are being treated as errors'
1816	@echo  '		Multiple levels can be combined with W=12 or W=123'
1817	@echo  '  make UT=1   [targets] Warn if a tracepoint is defined but not used.'
1818	@echo  '          [ This will be removed when all current unused tracepoints are eliminated. ]'
1819	@$(if $(dtstree), \
1820		echo '  make CHECK_DTBS=1 [targets] Check all generated dtb files against schema'; \
1821		echo '         This can be applied both to "dtbs" and to individual "foo.dtb" targets' ; \
1822		)
1823	@echo  ''
1824	@echo  'Execute "make" or "make all" to build all targets marked with [*] '
1825	@echo  'For further info see the ./README file'
1826
1827
1828help-board-dirs := $(addprefix help-,$(board-dirs))
1829
1830help-boards: $(help-board-dirs)
1831
1832boards-per-dir = $(sort $(notdir $(wildcard $(srctree)/arch/$(SRCARCH)/configs/$*/*_defconfig)))
1833
1834$(help-board-dirs): help-%:
1835	@echo  'Architecture-specific targets ($(SRCARCH) $*):'
1836	@$(if $(boards-per-dir), \
1837		$(foreach b, $(boards-per-dir), \
1838		printf "  %-24s - Build for %s\\n" $*/$(b) $(subst _defconfig,,$(b));) \
1839		echo '')
1840
1841
1842# Documentation targets
1843# ---------------------------------------------------------------------------
1844DOC_TARGETS := xmldocs latexdocs pdfdocs htmldocs epubdocs cleandocs \
1845	       linkcheckdocs dochelp refcheckdocs texinfodocs infodocs mandocs \
1846	       htmldocs-redirects
1847
1848PHONY += $(DOC_TARGETS)
1849$(DOC_TARGETS):
1850	$(Q)$(MAKE) $(build)=Documentation $@
1851
1852
1853# Rust targets
1854# ---------------------------------------------------------------------------
1855
1856# "Is Rust available?" target
1857PHONY += rustavailable
1858rustavailable:
1859	+$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh && echo "Rust is available!"
1860
1861# Documentation target
1862#
1863# Using the singular to avoid running afoul of `no-dot-config-targets`.
1864PHONY += rustdoc
1865rustdoc: prepare
1866	$(Q)$(MAKE) $(build)=rust $@
1867
1868# Testing target
1869PHONY += rusttest
1870rusttest: prepare
1871	$(Q)$(MAKE) $(build)=rust $@
1872
1873# Formatting targets
1874#
1875# Generated files as well as vendored crates are skipped.
1876PHONY += rustfmt rustfmtcheck
1877
1878rustfmt:
1879	$(Q)find $(srctree) $(RCS_FIND_IGNORE) \
1880		\( \
1881			-path $(srctree)/rust/proc-macro2 \
1882			-o -path $(srctree)/rust/quote \
1883			-o -path $(srctree)/rust/syn \
1884		\) -prune -o \
1885		-type f -a -name '*.rs' -a ! -name '*generated*' -print \
1886		| xargs $(RUSTFMT) $(rustfmt_flags)
1887
1888rustfmtcheck: rustfmt_flags = --check
1889rustfmtcheck: rustfmt
1890
1891# Misc
1892# ---------------------------------------------------------------------------
1893
1894PHONY += misc-check
1895misc-check:
1896	$(Q)$(srctree)/scripts/misc-check
1897
1898all: misc-check
1899
1900PHONY += scripts_gdb
1901scripts_gdb: prepare0
1902	$(Q)$(MAKE) $(build)=scripts/gdb
1903	$(Q)ln -fsn $(abspath $(srctree)/scripts/gdb/vmlinux-gdb.py)
1904
1905ifdef CONFIG_GDB_SCRIPTS
1906all: scripts_gdb
1907endif
1908
1909else # KBUILD_EXTMOD
1910
1911filechk_kernel.release = echo $(KERNELRELEASE)
1912
1913###
1914# External module support.
1915# When building external modules the kernel used as basis is considered
1916# read-only, and no consistency checks are made and the make
1917# system is not used on the basis kernel. If updates are required
1918# in the basis kernel ordinary make commands (without M=...) must be used.
1919
1920# We are always building only modules.
1921KBUILD_BUILTIN :=
1922KBUILD_MODULES := y
1923
1924build-dir := .
1925
1926clean-dirs := .
1927clean: private rm-files := Module.symvers modules.nsdeps compile_commands.json
1928
1929PHONY += prepare
1930# now expand this into a simple variable to reduce the cost of shell evaluations
1931prepare: CC_VERSION_TEXT := $(CC_VERSION_TEXT)
1932prepare:
1933	@if [ "$(CC_VERSION_TEXT)" != "$(CONFIG_CC_VERSION_TEXT)" ]; then \
1934		echo >&2 "warning: the compiler differs from the one used to build the kernel"; \
1935		echo >&2 "  The kernel was built by: $(CONFIG_CC_VERSION_TEXT)"; \
1936		echo >&2 "  You are using:           $(CC_VERSION_TEXT)"; \
1937	fi
1938
1939PHONY += help
1940help:
1941	@echo  '  Building external modules.'
1942	@echo  '  Syntax: make -C path/to/kernel/src M=$$PWD target'
1943	@echo  ''
1944	@echo  '  modules         - default target, build the module(s)'
1945	@echo  '  modules_install - install the module'
1946	@echo  '  clean           - remove generated files in module directory only'
1947	@echo  '  rust-analyzer	  - generate rust-project.json rust-analyzer support file'
1948	@echo  ''
1949
1950ifndef CONFIG_MODULES
1951modules modules_install: __external_modules_error
1952__external_modules_error:
1953	@echo >&2 '***'
1954	@echo >&2 '*** The present kernel disabled CONFIG_MODULES.'
1955	@echo >&2 '*** You cannot build or install external modules.'
1956	@echo >&2 '***'
1957	@false
1958endif
1959
1960endif # KBUILD_EXTMOD
1961
1962# ---------------------------------------------------------------------------
1963# Modules
1964
1965PHONY += modules modules_install modules_sign modules_prepare
1966
1967modules_install:
1968	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst \
1969	sign-only=$(if $(filter modules_install,$(MAKECMDGOALS)),,y)
1970
1971ifeq ($(CONFIG_MODULE_SIG),y)
1972# modules_sign is a subset of modules_install.
1973# 'make modules_install modules_sign' is equivalent to 'make modules_install'.
1974modules_sign: modules_install
1975	@:
1976else
1977modules_sign:
1978	@echo >&2 '***'
1979	@echo >&2 '*** CONFIG_MODULE_SIG is disabled. You cannot sign modules.'
1980	@echo >&2 '***'
1981	@false
1982endif
1983
1984ifdef CONFIG_MODULES
1985
1986modules.order: $(build-dir)
1987	@:
1988
1989# KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
1990# This is solely useful to speed up test compiles.
1991modules: modpost
1992ifneq ($(KBUILD_MODPOST_NOFINAL),1)
1993	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modfinal
1994endif
1995
1996PHONY += modules_check
1997modules_check: modules.order
1998	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/modules-check.sh $<
1999
2000else # CONFIG_MODULES
2001
2002modules:
2003	@:
2004
2005KBUILD_MODULES :=
2006
2007endif # CONFIG_MODULES
2008
2009PHONY += modpost
2010modpost: $(if $(single-build),, $(if $(KBUILD_BUILTIN), vmlinux.o)) \
2011	 $(if $(KBUILD_MODULES), modules_check)
2012	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
2013
2014# Single targets
2015# ---------------------------------------------------------------------------
2016# To build individual files in subdirectories, you can do like this:
2017#
2018#   make foo/bar/baz.s
2019#
2020# The supported suffixes for single-target are listed in 'single-targets'
2021#
2022# To build only under specific subdirectories, you can do like this:
2023#
2024#   make foo/bar/baz/
2025
2026ifdef single-build
2027
2028# .ko is special because modpost is needed
2029single-ko := $(sort $(filter %.ko, $(MAKECMDGOALS)))
2030single-no-ko := $(filter-out $(single-ko), $(MAKECMDGOALS)) \
2031		$(foreach x, o mod, $(patsubst %.ko, %.$x, $(single-ko)))
2032
2033$(single-ko): single_modules
2034	@:
2035$(single-no-ko): $(build-dir)
2036	@:
2037
2038# Remove modules.order when done because it is not the real one.
2039PHONY += single_modules
2040single_modules: $(single-no-ko) modules_prepare
2041	$(Q){ $(foreach m, $(single-ko), echo $(m:%.ko=%.o);) } > modules.order
2042	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
2043ifneq ($(KBUILD_MODPOST_NOFINAL),1)
2044	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modfinal
2045endif
2046	$(Q)rm -f modules.order
2047
2048single-goals := $(addprefix $(build-dir)/, $(single-no-ko))
2049
2050KBUILD_MODULES := y
2051
2052endif
2053
2054prepare: outputmakefile
2055
2056# Preset locale variables to speed up the build process. Limit locale
2057# tweaks to this spot to avoid wrong language settings when running
2058# make menuconfig etc.
2059# Error messages still appears in the original language
2060PHONY += $(build-dir)
2061$(build-dir): prepare
2062	$(Q)$(MAKE) $(build)=$@ need-builtin=1 need-modorder=1 $(single-goals)
2063
2064clean-dirs := $(addprefix _clean_, $(clean-dirs))
2065PHONY += $(clean-dirs) clean
2066$(clean-dirs):
2067	$(Q)$(MAKE) $(clean)=$(patsubst _clean_%,%,$@)
2068
2069clean: $(clean-dirs)
2070	$(call cmd,rmfiles)
2071	@find . $(RCS_FIND_IGNORE) \
2072		\( -name '*.[aios]' -o -name '*.rsi' -o -name '*.ko' -o -name '.*.cmd' \
2073		-o -name '*.ko.*' \
2074		-o -name '*.dtb' -o -name '*.dtbo' \
2075		-o -name '*.dtb.S' -o -name '*.dtbo.S' \
2076		-o -name '*.dt.yaml' -o -name 'dtbs-list' \
2077		-o -name '*.dwo' -o -name '*.lst' \
2078		-o -name '*.su' -o -name '*.mod' \
2079		-o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
2080		-o -name '*.lex.c' -o -name '*.tab.[ch]' \
2081		-o -name '*.asn1.[ch]' \
2082		-o -name '*.symtypes' -o -name 'modules.order' \
2083		-o -name '*.c.[012]*.*' \
2084		-o -name '*.ll' \
2085		-o -name '*.gcno' \
2086		\) -type f -print \
2087		-o -name '.tmp_*' -print \
2088		| xargs rm -rf
2089
2090# Generate tags for editors
2091# ---------------------------------------------------------------------------
2092quiet_cmd_tags = GEN     $@
2093      cmd_tags = $(BASH) $(srctree)/scripts/tags.sh $@
2094
2095tags TAGS cscope gtags: FORCE
2096	$(call cmd,tags)
2097
2098# Generate rust-project.json (a file that describes the structure of non-Cargo
2099# Rust projects) for rust-analyzer (an implementation of the Language Server
2100# Protocol).
2101PHONY += rust-analyzer
2102rust-analyzer:
2103	+$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh
2104ifdef KBUILD_EXTMOD
2105# FIXME: external modules must not descend into a sub-directory of the kernel
2106	$(Q)$(MAKE) $(build)=$(objtree)/rust src=$(srctree)/rust $@
2107else
2108	$(Q)$(MAKE) $(build)=rust $@
2109endif
2110
2111# Script to generate missing namespace dependencies
2112# ---------------------------------------------------------------------------
2113
2114PHONY += nsdeps
2115nsdeps: export KBUILD_NSDEPS=1
2116nsdeps: modules
2117	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/nsdeps
2118
2119# Clang Tooling
2120# ---------------------------------------------------------------------------
2121
2122quiet_cmd_gen_compile_commands = GEN     $@
2123      cmd_gen_compile_commands = $(PYTHON3) $< -a $(AR) -o $@ $(filter-out $<, $(real-prereqs))
2124
2125compile_commands.json: $(srctree)/scripts/clang-tools/gen_compile_commands.py \
2126	$(if $(KBUILD_EXTMOD),, vmlinux.a $(KBUILD_VMLINUX_LIBS)) \
2127	$(if $(CONFIG_MODULES), modules.order) FORCE
2128	$(call if_changed,gen_compile_commands)
2129
2130targets += compile_commands.json
2131
2132PHONY += clang-tidy clang-analyzer
2133
2134ifdef CONFIG_CC_IS_CLANG
2135quiet_cmd_clang_tools = CHECK   $<
2136      cmd_clang_tools = $(PYTHON3) $(srctree)/scripts/clang-tools/run-clang-tools.py $@ $<
2137
2138clang-tidy clang-analyzer: compile_commands.json
2139	$(call cmd,clang_tools)
2140else
2141clang-tidy clang-analyzer:
2142	@echo "$@ requires CC=clang" >&2
2143	@false
2144endif
2145
2146# Scripts to check various things for consistency
2147# ---------------------------------------------------------------------------
2148
2149PHONY += includecheck versioncheck coccicheck
2150
2151includecheck:
2152	find $(srctree)/* $(RCS_FIND_IGNORE) \
2153		-name '*.[hcS]' -type f -print | sort \
2154		| xargs $(PERL) -w $(srctree)/scripts/checkincludes.pl
2155
2156versioncheck:
2157	find $(srctree)/* $(RCS_FIND_IGNORE) \
2158		-name '*.[hcS]' -type f -print | sort \
2159		| xargs $(PERL) -w $(srctree)/scripts/checkversion.pl
2160
2161coccicheck:
2162	$(Q)$(BASH) $(srctree)/scripts/$@
2163
2164PHONY += checkstack kernelrelease kernelversion image_name
2165
2166# UML needs a little special treatment here.  It wants to use the host
2167# toolchain, so needs $(SUBARCH) passed to checkstack.pl.  Everyone
2168# else wants $(ARCH), including people doing cross-builds, which means
2169# that $(SUBARCH) doesn't work here.
2170ifeq ($(ARCH), um)
2171CHECKSTACK_ARCH := $(SUBARCH)
2172else
2173CHECKSTACK_ARCH := $(ARCH)
2174endif
2175MINSTACKSIZE	?= 100
2176checkstack:
2177	$(OBJDUMP) -d vmlinux $$(find . -name '*.ko') | \
2178	$(PERL) $(srctree)/scripts/checkstack.pl $(CHECKSTACK_ARCH) $(MINSTACKSIZE)
2179
2180kernelrelease:
2181	@$(filechk_kernel.release)
2182
2183kernelversion:
2184	@echo $(KERNELVERSION)
2185
2186image_name:
2187	@echo $(KBUILD_IMAGE)
2188
2189PHONY += run-command
2190run-command:
2191	$(Q)$(KBUILD_RUN_COMMAND)
2192
2193quiet_cmd_rmfiles = $(if $(wildcard $(rm-files)),CLEAN   $(wildcard $(rm-files)))
2194      cmd_rmfiles = rm -rf $(rm-files)
2195
2196# read saved command lines for existing targets
2197existing-targets := $(wildcard $(sort $(targets)))
2198
2199-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
2200
2201endif # config-build
2202endif # mixed-build
2203endif # need-sub-make
2204
2205PHONY += FORCE
2206FORCE:
2207
2208# Declare the contents of the PHONY variable as phony.  We keep that
2209# information in a variable so we can use it in if_changed and friends.
2210.PHONY: $(PHONY)
2211