1 # SPDX-License-Identifier: GPL-2.0
6 NAME = Kleptomaniac Octopus
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.
14 $(if $(filter __%, $(MAKECMDGOALS)), \
15 $(error targets prefixed with '__' are only for internal use))
17 # That's our default target when none is given on the command line
21 # We are using a recursive build, so we need to do a little thinking
22 # to get the ordering right.
24 # Most importantly: sub-Makefiles should only ever modify files in
25 # their own directory. If in some directory we have a dependency on
26 # a file in another dir (which doesn't happen often, but it's often
27 # unavoidable when linking the built-in.a targets which finally
28 # turn into vmlinux), we will call a sub make in that other dir, and
29 # after that we are sure that everything which is in that other dir
32 # The only cases where we need to modify files which have global
33 # effects are thus separated out and done before the recursive
34 # descending is started. They are now explicitly listed as the
37 ifneq ($(sub_make_done),1)
39 # Do not use make's built-in rules and variables
40 # (this increases performance and avoids hard-to-debug behaviour)
43 # Avoid funny character set dependencies
47 export LC_COLLATE LC_NUMERIC
49 # Avoid interference with shell env settings
53 # ---------------------------------------------------------------------------
55 # Normally, we echo the whole command before executing it. By making
56 # that echo $($(quiet)$(cmd)), we now have the possibility to set
57 # $(quiet) to choose other forms of output instead, e.g.
59 # quiet_cmd_cc_o_c = Compiling $(RELDIR)/$@
60 # cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
62 # If $(quiet) is empty, the whole command will be printed.
63 # If it is set to "quiet_", only the short version will be printed.
64 # If it is set to "silent_", nothing will be printed at all, since
65 # the variable $(silent_cmd_cc_o_c) doesn't exist.
67 # A simple variant is to prefix commands with $(Q) - that's useful
68 # for commands that shall be hidden in non-verbose mode.
72 # If KBUILD_VERBOSE equals 0 then the above command will be hidden.
73 # If KBUILD_VERBOSE equals 1 then the above command is displayed.
74 # If KBUILD_VERBOSE equals 2 then give the reason why each target is rebuilt.
76 # To put more focus on warnings, be less verbose as default
77 # Use 'make V=1' to see the full commands
79 ifeq ("$(origin V)", "command line")
86 ifeq ($(KBUILD_VERBOSE),1)
94 # If the user is running make -s (silent mode), suppress echoing of
97 ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)
101 export quiet Q KBUILD_VERBOSE
103 # Kbuild will save output files in the current working directory.
104 # This does not need to match to the root of the kernel source tree.
106 # For example, you can do this:
108 # cd /dir/to/store/output/files; make -f /dir/to/kernel/source/Makefile
110 # If you want to save output files in a different location, there are
111 # two syntaxes to specify it.
114 # Use "make O=dir/to/store/output/files/"
116 # 2) Set KBUILD_OUTPUT
117 # Set the environment variable KBUILD_OUTPUT to point to the output directory.
118 # export KBUILD_OUTPUT=dir/to/store/output/files/; make
120 # The O= assignment takes precedence over the KBUILD_OUTPUT environment
123 # Do we want to change the working directory?
124 ifeq ("$(origin O)", "command line")
125 KBUILD_OUTPUT := $(O)
128 ifneq ($(KBUILD_OUTPUT),)
129 # Make's built-in functions such as $(abspath ...), $(realpath ...) cannot
130 # expand a shell special character '~'. We use a somewhat tedious way here.
131 abs_objtree := $(shell mkdir -p $(KBUILD_OUTPUT) && cd $(KBUILD_OUTPUT) && pwd)
132 $(if $(abs_objtree),, \
133 $(error failed to create output directory "$(KBUILD_OUTPUT)"))
135 # $(realpath ...) resolves symlinks
136 abs_objtree := $(realpath $(abs_objtree))
138 abs_objtree := $(CURDIR)
139 endif # ifneq ($(KBUILD_OUTPUT),)
141 ifeq ($(abs_objtree),$(CURDIR))
142 # Suppress "Entering directory ..." unless we are changing the work directory.
143 MAKEFLAGS += --no-print-directory
148 abs_srctree := $(realpath $(dir $(lastword $(MAKEFILE_LIST))))
150 ifneq ($(words $(subst :, ,$(abs_srctree))), 1)
151 $(error source directory cannot contain spaces or colons)
154 ifneq ($(abs_srctree),$(abs_objtree))
155 # Look for make include files relative to root of kernel src
157 # This does not become effective immediately because MAKEFLAGS is re-parsed
158 # once after the Makefile is read. We need to invoke sub-make.
159 MAKEFLAGS += --include-dir=$(abs_srctree)
163 this-makefile := $(lastword $(MAKEFILE_LIST))
165 ifneq ($(filter 3.%,$(MAKE_VERSION)),)
166 # 'MAKEFLAGS += -rR' does not immediately become effective for GNU Make 3.x
167 # We need to invoke sub-make to avoid implicit rules in the top Makefile.
169 # Cancel implicit rules for this Makefile.
173 export abs_srctree abs_objtree
174 export sub_make_done := 1
176 ifeq ($(need-sub-make),1)
178 PHONY += $(MAKECMDGOALS) __sub-make
180 $(filter-out $(this-makefile), $(MAKECMDGOALS)) __all: __sub-make
183 # Invoke a second make in the output directory, passing relevant variables
185 $(Q)$(MAKE) -C $(abs_objtree) -f $(abs_srctree)/Makefile $(MAKECMDGOALS)
187 endif # need-sub-make
188 endif # sub_make_done
190 # We process the rest of the Makefile if this is the final invocation of make
191 ifeq ($(need-sub-make),)
193 # Do not print "Entering directory ...",
194 # but we want to display it when entering to the output directory
195 # so that IDEs/editors are able to understand relative filenames.
196 MAKEFLAGS += --no-print-directory
198 # Call a source code checker (by default, "sparse") as part of the
201 # Use 'make C=1' to enable checking of only re-compiled files.
202 # Use 'make C=2' to enable checking of *all* source files, regardless
203 # of whether they are re-compiled or not.
205 # See the file "Documentation/dev-tools/sparse.rst" for more details,
206 # including where to get the "sparse" utility.
208 ifeq ("$(origin C)", "command line")
209 KBUILD_CHECKSRC = $(C)
211 ifndef KBUILD_CHECKSRC
215 # Use make M=dir or set the environment variable KBUILD_EXTMOD to specify the
216 # directory of external module to build. Setting M= takes precedence.
217 ifeq ("$(origin M)", "command line")
218 KBUILD_EXTMOD := $(M)
221 $(if $(word 2, $(KBUILD_EXTMOD)), \
222 $(error building multiple external modules is not supported))
224 export KBUILD_CHECKSRC KBUILD_EXTMOD
226 extmod-prefix = $(if $(KBUILD_EXTMOD),$(KBUILD_EXTMOD)/)
228 ifeq ($(abs_srctree),$(abs_objtree))
229 # building in the source tree
231 building_out_of_srctree :=
233 ifeq ($(abs_srctree)/,$(dir $(abs_objtree)))
234 # building in a subdirectory of the source tree
237 srctree := $(abs_srctree)
239 building_out_of_srctree := 1
242 ifneq ($(KBUILD_ABS_SRCTREE),)
243 srctree := $(abs_srctree)
249 export building_out_of_srctree srctree objtree VPATH
251 # To make sure we do not include .config for any of the *config targets
252 # catch them early, and hand them over to scripts/kconfig/Makefile
253 # It is allowed to specify more targets when calling make, including
254 # mixing *config targets and build targets.
255 # For example 'make oldconfig all'.
256 # Detect when mixed targets is specified, and make a second invocation
257 # of make so .config is not included in this case either (for *config).
259 version_h := include/generated/uapi/linux/version.h
260 old_version_h := include/linux/version.h
262 clean-targets := %clean mrproper cleandocs
263 no-dot-config-targets := $(clean-targets) \
264 cscope gtags TAGS tags help% %docs check% coccicheck \
265 $(version_h) headers headers_% archheaders archscripts \
266 %asm-generic kernelversion %src-pkg dt_binding_check \
268 no-sync-config-targets := $(no-dot-config-targets) install %install \
270 single-targets := %.a %.i %.ko %.lds %.ll %.lst %.mod %.o %.s %.symtypes %/
278 ifneq ($(filter $(no-dot-config-targets), $(MAKECMDGOALS)),)
279 ifeq ($(filter-out $(no-dot-config-targets), $(MAKECMDGOALS)),)
284 ifneq ($(filter $(no-sync-config-targets), $(MAKECMDGOALS)),)
285 ifeq ($(filter-out $(no-sync-config-targets), $(MAKECMDGOALS)),)
290 ifneq ($(KBUILD_EXTMOD),)
294 ifeq ($(KBUILD_EXTMOD),)
295 ifneq ($(filter config %config,$(MAKECMDGOALS)),)
297 ifneq ($(words $(MAKECMDGOALS)),1)
303 # We cannot build single targets and the others at the same time
304 ifneq ($(filter $(single-targets), $(MAKECMDGOALS)),)
306 ifneq ($(filter-out $(single-targets), $(MAKECMDGOALS)),)
311 # For "make -j clean all", "make -j mrproper defconfig all", etc.
312 ifneq ($(filter $(clean-targets),$(MAKECMDGOALS)),)
313 ifneq ($(filter-out $(clean-targets),$(MAKECMDGOALS)),)
318 # install and modules_install need also be processed one by one
319 ifneq ($(filter install,$(MAKECMDGOALS)),)
320 ifneq ($(filter modules_install,$(MAKECMDGOALS)),)
326 # ===========================================================================
327 # We're called with mixed targets (*config and build targets).
328 # Handle them one by one.
330 PHONY += $(MAKECMDGOALS) __build_one_by_one
332 $(MAKECMDGOALS): __build_one_by_one
337 for i in $(MAKECMDGOALS); do \
338 $(MAKE) -f $(srctree)/Makefile $$i; \
343 include scripts/Kbuild.include
345 # Read KERNELRELEASE from include/config/kernel.release (if it exists)
346 KERNELRELEASE = $(shell cat include/config/kernel.release 2> /dev/null)
347 KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION)
348 export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION
350 include scripts/subarch.include
352 # Cross compiling and selecting different set of gcc/bin-utils
353 # ---------------------------------------------------------------------------
355 # When performing cross compilation for other architectures ARCH shall be set
356 # to the target architecture. (See arch/* for the possibilities).
357 # ARCH can be set during invocation of make:
359 # Another way is to have ARCH set in the environment.
360 # The default ARCH is the host where make is executed.
362 # CROSS_COMPILE specify the prefix used for all executables used
363 # during compilation. Only gcc and related bin-utils executables
364 # are prefixed with $(CROSS_COMPILE).
365 # CROSS_COMPILE can be set on the command line
366 # make CROSS_COMPILE=ia64-linux-
367 # Alternatively CROSS_COMPILE can be set in the environment.
368 # Default value for CROSS_COMPILE is not to prefix executables
369 # Note: Some architectures assign CROSS_COMPILE in their arch/*/Makefile
372 # Architecture as present in compile.h
373 UTS_MACHINE := $(ARCH)
376 # Additional ARCH settings for x86
380 ifeq ($(ARCH),x86_64)
384 # Additional ARCH settings for sparc
385 ifeq ($(ARCH),sparc32)
388 ifeq ($(ARCH),sparc64)
392 # Additional ARCH settings for sh
397 KCONFIG_CONFIG ?= .config
398 export KCONFIG_CONFIG
400 # Default file for 'make defconfig'. This may be overridden by arch-Makefile.
401 export KBUILD_DEFCONFIG := defconfig
403 # SHELL used by kbuild
406 HOST_LFS_CFLAGS := $(shell getconf LFS_CFLAGS 2>/dev/null)
407 HOST_LFS_LDFLAGS := $(shell getconf LFS_LDFLAGS 2>/dev/null)
408 HOST_LFS_LIBS := $(shell getconf LFS_LIBS 2>/dev/null)
418 export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
419 -O2 -fomit-frame-pointer -std=gnu89
420 export KBUILD_USERLDFLAGS :=
422 KBUILD_HOSTCFLAGS := $(KBUILD_USERCFLAGS) $(HOST_LFS_CFLAGS) $(HOSTCFLAGS)
423 KBUILD_HOSTCXXFLAGS := -Wall -O2 $(HOST_LFS_CFLAGS) $(HOSTCXXFLAGS)
424 KBUILD_HOSTLDFLAGS := $(HOST_LFS_LDFLAGS) $(HOSTLDFLAGS)
425 KBUILD_HOSTLDLIBS := $(HOST_LFS_LIBS) $(HOSTLDLIBS)
427 # Make variables (CC, etc...)
434 OBJCOPY = llvm-objcopy
435 OBJDUMP = llvm-objdump
436 READELF = llvm-readelf
440 CC = $(CROSS_COMPILE)gcc
441 LD = $(CROSS_COMPILE)ld
442 AR = $(CROSS_COMPILE)ar
443 NM = $(CROSS_COMPILE)nm
444 OBJCOPY = $(CROSS_COMPILE)objcopy
445 OBJDUMP = $(CROSS_COMPILE)objdump
446 READELF = $(CROSS_COMPILE)readelf
447 OBJSIZE = $(CROSS_COMPILE)size
448 STRIP = $(CROSS_COMPILE)strip
451 RESOLVE_BTFIDS = $(objtree)/tools/bpf/resolve_btfids/resolve_btfids
455 INSTALLKERNEL := installkernel
456 DEPMOD = /sbin/depmod
470 CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
471 -Wbitwise -Wno-return-void -Wno-unknown-attribute $(CF)
480 # Use USERINCLUDE when you must reference the UAPI directories only.
482 -I$(srctree)/arch/$(SRCARCH)/include/uapi \
483 -I$(objtree)/arch/$(SRCARCH)/include/generated/uapi \
484 -I$(srctree)/include/uapi \
485 -I$(objtree)/include/generated/uapi \
486 -include $(srctree)/include/linux/kconfig.h
488 # Use LINUXINCLUDE when you must reference the include/ directory.
489 # Needed to be compatible with the O= option
491 -I$(srctree)/arch/$(SRCARCH)/include \
492 -I$(objtree)/arch/$(SRCARCH)/include/generated \
493 $(if $(building_out_of_srctree),-I$(srctree)/include) \
494 -I$(objtree)/include \
497 KBUILD_AFLAGS := -D__ASSEMBLY__ -fno-PIE
498 KBUILD_CFLAGS := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \
499 -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE \
500 -Werror=implicit-function-declaration -Werror=implicit-int \
501 -Wno-format-security \
503 KBUILD_CPPFLAGS := -D__KERNEL__
504 KBUILD_AFLAGS_KERNEL :=
505 KBUILD_CFLAGS_KERNEL :=
506 KBUILD_AFLAGS_MODULE := -DMODULE
507 KBUILD_CFLAGS_MODULE := -DMODULE
508 KBUILD_LDFLAGS_MODULE :=
509 export KBUILD_LDS_MODULE := $(srctree)/scripts/module-common.lds
511 GCC_PLUGINS_CFLAGS :=
514 export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC
515 export CPP AR NM STRIP OBJCOPY OBJDUMP OBJSIZE READELF PAHOLE RESOLVE_BTFIDS LEX YACC AWK INSTALLKERNEL
516 export PERL PYTHON PYTHON3 CHECK CHECKFLAGS MAKE UTS_MACHINE HOSTCXX
517 export KGZIP KBZIP2 KLZOP LZMA LZ4 XZ ZSTD
518 export KBUILD_HOSTCXXFLAGS KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS LDFLAGS_MODULE
520 export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS KBUILD_LDFLAGS
521 export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
522 export CFLAGS_KASAN CFLAGS_KASAN_NOSANITIZE CFLAGS_UBSAN CFLAGS_KCSAN
523 export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
524 export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
525 export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
527 # Files to ignore in find ... statements
529 export RCS_FIND_IGNORE := \( -name SCCS -o -name BitKeeper -o -name .svn -o \
530 -name CVS -o -name .pc -o -name .hg -o -name .git \) \
532 export RCS_TAR_IGNORE := --exclude SCCS --exclude BitKeeper --exclude .svn \
533 --exclude CVS --exclude .pc --exclude .hg --exclude .git
535 # ===========================================================================
536 # Rules shared between *config targets and build targets
538 # Basic helpers built in scripts/basic/
539 PHONY += scripts_basic
541 $(Q)$(MAKE) $(build)=scripts/basic
542 $(Q)rm -f .tmp_quiet_recordmcount
544 PHONY += outputmakefile
545 # Before starting out-of-tree build, make sure the source tree is clean.
546 # outputmakefile generates a Makefile in the output directory, if using a
547 # separate output directory. This allows convenient use of make in the
549 # At the same time when output Makefile generated, generate .gitignore to
550 # ignore whole output directory
552 ifdef building_out_of_srctree
553 $(Q)if [ -f $(srctree)/.config -o \
554 -d $(srctree)/include/config -o \
555 -d $(srctree)/arch/$(SRCARCH)/include/generated ]; then \
557 echo >&2 "*** The source tree is not clean, please run 'make$(if $(findstring command line, $(origin ARCH)), ARCH=$(ARCH)) mrproper'"; \
558 echo >&2 "*** in $(abs_srctree)";\
562 $(Q)ln -fsn $(srctree) source
563 $(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile $(srctree)
564 $(Q)test -e .gitignore || \
565 { echo "# this is build directory, ignore it"; echo "*"; } > .gitignore
568 ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
569 ifneq ($(CROSS_COMPILE),)
570 CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%))
571 GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))
572 CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
573 GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..)
575 ifneq ($(GCC_TOOLCHAIN),)
576 CLANG_FLAGS += --gcc-toolchain=$(GCC_TOOLCHAIN)
578 ifneq ($(LLVM_IAS),1)
579 CLANG_FLAGS += -no-integrated-as
581 CLANG_FLAGS += -Werror=unknown-warning-option
582 KBUILD_CFLAGS += $(CLANG_FLAGS)
583 KBUILD_AFLAGS += $(CLANG_FLAGS)
587 # The expansion should be delayed until arch/$(SRCARCH)/Makefile is included.
588 # Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile.
589 # CC_VERSION_TEXT is referenced from Kconfig (so it needs export),
590 # and from include/config/auto.conf.cmd to detect the compiler upgrade.
591 CC_VERSION_TEXT = $(shell $(CC) --version 2>/dev/null | head -n 1)
594 # ===========================================================================
595 # *config targets only - make sure prerequisites are updated, and descend
596 # in scripts/kconfig to make the *config target
598 # Read arch specific Makefile to set KBUILD_DEFCONFIG as needed.
599 # KBUILD_DEFCONFIG may point out an alternative default configuration
600 # used for 'make defconfig'
601 include arch/$(SRCARCH)/Makefile
602 export KBUILD_DEFCONFIG KBUILD_KCONFIG CC_VERSION_TEXT
604 config: outputmakefile scripts_basic FORCE
605 $(Q)$(MAKE) $(build)=scripts/kconfig $@
607 %config: outputmakefile scripts_basic FORCE
608 $(Q)$(MAKE) $(build)=scripts/kconfig $@
611 # ===========================================================================
612 # Build targets only - this includes vmlinux, arch specific targets, clean
613 # targets and others. In general all targets except *config targets.
615 # If building an external module we do not care about the all: rule
616 # but instead __all depend on modules
618 ifeq ($(KBUILD_EXTMOD),)
624 # Decide whether to build built-in, modular, or both.
625 # Normally, just do built-in.
630 # If we have only "make modules", don't compile built-in objects.
631 ifeq ($(MAKECMDGOALS),modules)
635 # If we have "make <whatever> modules", compile modules
636 # in addition to whatever we do anyway.
637 # Just "make" or "make all" shall build modules as well
639 ifneq ($(filter all modules nsdeps,$(MAKECMDGOALS)),)
643 ifeq ($(MAKECMDGOALS),)
647 export KBUILD_MODULES KBUILD_BUILTIN
650 include include/config/auto.conf
653 ifeq ($(KBUILD_EXTMOD),)
654 # Objects we will link into vmlinux / subdirs we need to visit
656 drivers-y := drivers/ sound/
657 drivers-$(CONFIG_SAMPLES) += samples/
658 drivers-y += net/ virt/
660 endif # KBUILD_EXTMOD
662 # The all: target is the default when no target is given on the
664 # This allow a user to issue only 'make' to build a kernel including modules
665 # Defaults to vmlinux, but the arch makefile usually adds further targets
668 CFLAGS_GCOV := -fprofile-arcs -ftest-coverage \
669 $(call cc-option,-fno-tree-loop-im) \
670 $(call cc-disable-warning,maybe-uninitialized,)
673 # The arch Makefiles can override CC_FLAGS_FTRACE. We may also append it later.
674 ifdef CONFIG_FUNCTION_TRACER
675 CC_FLAGS_FTRACE := -pg
678 RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern -mindirect-branch-register
679 RETPOLINE_VDSO_CFLAGS_GCC := -mindirect-branch=thunk-inline -mindirect-branch-register
680 RETPOLINE_CFLAGS_CLANG := -mretpoline-external-thunk
681 RETPOLINE_VDSO_CFLAGS_CLANG := -mretpoline
682 RETPOLINE_CFLAGS := $(call cc-option,$(RETPOLINE_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_CFLAGS_CLANG)))
683 RETPOLINE_VDSO_CFLAGS := $(call cc-option,$(RETPOLINE_VDSO_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_VDSO_CFLAGS_CLANG)))
684 export RETPOLINE_CFLAGS
685 export RETPOLINE_VDSO_CFLAGS
687 include arch/$(SRCARCH)/Makefile
690 ifdef may-sync-config
691 # Read in dependencies to all Kconfig* files, make sure to run syncconfig if
692 # changes are detected. This should be included after arch/$(SRCARCH)/Makefile
693 # because some architectures define CROSS_COMPILE there.
694 include include/config/auto.conf.cmd
698 @echo >&2 '*** Configuration file "$@" not found!'
700 @echo >&2 '*** Please run some configurator (e.g. "make oldconfig" or'
701 @echo >&2 '*** "make menuconfig" or "make xconfig").'
705 # The actual configuration files used during the build are stored in
706 # include/generated/ and include/config/. Update them if .config is newer than
707 # include/config/auto.conf (which mirrors .config).
709 # This exploits the 'multi-target pattern rule' trick.
710 # The syncconfig should be executed only once to make all the targets.
711 # (Note: use the grouped target '&:' when we bump to GNU Make 4.3)
712 %/config/auto.conf %/config/auto.conf.cmd %/generated/autoconf.h: $(KCONFIG_CONFIG)
713 $(Q)$(MAKE) -f $(srctree)/Makefile syncconfig
714 else # !may-sync-config
715 # External modules and some install targets need include/generated/autoconf.h
716 # and include/config/auto.conf but do not care if they are up-to-date.
717 # Use auto.conf to trigger the test
718 PHONY += include/config/auto.conf
720 include/config/auto.conf:
721 $(Q)test -e include/generated/autoconf.h -a -e $@ || ( \
723 echo >&2 " ERROR: Kernel configuration is invalid."; \
724 echo >&2 " include/generated/autoconf.h or $@ are missing.";\
725 echo >&2 " Run 'make oldconfig && make prepare' on kernel src to fix it."; \
729 endif # may-sync-config
732 KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,)
733 KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
734 KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
735 KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow)
736 KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
738 ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
740 else ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3
742 else ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
746 # Tell gcc to never replace conditional load with a non-conditional one
747 KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0)
748 KBUILD_CFLAGS += $(call cc-option,-fno-allow-store-data-races)
750 include scripts/Makefile.kcov
751 include scripts/Makefile.gcc-plugins
753 ifdef CONFIG_READABLE_ASM
754 # Disable optimizations that make assembler listings hard to read.
755 # reorder blocks reorders the control in the function
756 # ipa clone creates specialized cloned functions
757 # partial inlining inlines only parts of functions
758 KBUILD_CFLAGS += $(call cc-option,-fno-reorder-blocks,) \
759 $(call cc-option,-fno-ipa-cp-clone,) \
760 $(call cc-option,-fno-partial-inlining)
763 ifneq ($(CONFIG_FRAME_WARN),0)
764 KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_FRAME_WARN)
767 stackp-flags-$(CONFIG_CC_HAS_STACKPROTECTOR_NONE) := -fno-stack-protector
768 stackp-flags-$(CONFIG_STACKPROTECTOR) := -fstack-protector
769 stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong
771 KBUILD_CFLAGS += $(stackp-flags-y)
773 ifdef CONFIG_CC_IS_CLANG
774 KBUILD_CPPFLAGS += -Qunused-arguments
775 KBUILD_CFLAGS += -Wno-format-invalid-specifier
776 KBUILD_CFLAGS += -Wno-gnu
777 # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the
778 # source of a reference will be _MergedGlobals and not on of the whitelisted names.
779 # See modpost pattern 2
780 KBUILD_CFLAGS += -mno-global-merge
783 # These warnings generated too much noise in a regular build.
784 # Use make W=1 to enable them (see scripts/Makefile.extrawarn)
785 KBUILD_CFLAGS += -Wno-unused-but-set-variable
787 # Warn about unmarked fall-throughs in switch statement.
788 # Disabled for clang while comment to attribute conversion happens and
789 # https://github.com/ClangBuiltLinux/linux/issues/636 is discussed.
790 KBUILD_CFLAGS += $(call cc-option,-Wimplicit-fallthrough,)
793 KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
794 ifdef CONFIG_FRAME_POINTER
795 KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls
797 # Some targets (ARM with Thumb2, for example), can't be built with frame
798 # pointers. For those, we don't have FUNCTION_TRACER automatically
799 # select FRAME_POINTER. However, FUNCTION_TRACER adds -pg, and this is
800 # incompatible with -fomit-frame-pointer with current GCC, so we don't use
801 # -fomit-frame-pointer with FUNCTION_TRACER.
802 ifndef CONFIG_FUNCTION_TRACER
803 KBUILD_CFLAGS += -fomit-frame-pointer
807 # Initialize all stack variables with a 0xAA pattern.
808 ifdef CONFIG_INIT_STACK_ALL_PATTERN
809 KBUILD_CFLAGS += -ftrivial-auto-var-init=pattern
812 # Initialize all stack variables with a zero value.
813 ifdef CONFIG_INIT_STACK_ALL_ZERO
814 # Future support for zero initialization is still being debated, see
815 # https://bugs.llvm.org/show_bug.cgi?id=45497. These flags are subject to being
816 # renamed or dropped.
817 KBUILD_CFLAGS += -ftrivial-auto-var-init=zero
818 KBUILD_CFLAGS += -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
821 DEBUG_CFLAGS := $(call cc-option, -fno-var-tracking-assignments)
823 ifdef CONFIG_DEBUG_INFO
824 ifdef CONFIG_DEBUG_INFO_SPLIT
825 DEBUG_CFLAGS += -gsplit-dwarf
829 KBUILD_AFLAGS += -Wa,-gdwarf-2
831 ifdef CONFIG_DEBUG_INFO_DWARF4
832 DEBUG_CFLAGS += -gdwarf-4
835 ifdef CONFIG_DEBUG_INFO_REDUCED
836 DEBUG_CFLAGS += $(call cc-option, -femit-struct-debug-baseonly) \
837 $(call cc-option,-fno-var-tracking)
840 ifdef CONFIG_DEBUG_INFO_COMPRESSED
841 DEBUG_CFLAGS += -gz=zlib
842 KBUILD_AFLAGS += -gz=zlib
843 KBUILD_LDFLAGS += --compress-debug-sections=zlib
846 KBUILD_CFLAGS += $(DEBUG_CFLAGS)
849 ifdef CONFIG_FUNCTION_TRACER
850 ifdef CONFIG_FTRACE_MCOUNT_RECORD
851 # gcc 5 supports generating the mcount tables directly
852 ifeq ($(call cc-option-yn,-mrecord-mcount),y)
853 CC_FLAGS_FTRACE += -mrecord-mcount
854 export CC_USING_RECORD_MCOUNT := 1
856 ifdef CONFIG_HAVE_NOP_MCOUNT
857 ifeq ($(call cc-option-yn, -mnop-mcount),y)
858 CC_FLAGS_FTRACE += -mnop-mcount
859 CC_FLAGS_USING += -DCC_USING_NOP_MCOUNT
863 ifdef CONFIG_HAVE_FENTRY
864 ifeq ($(call cc-option-yn, -mfentry),y)
865 CC_FLAGS_FTRACE += -mfentry
866 CC_FLAGS_USING += -DCC_USING_FENTRY
869 export CC_FLAGS_FTRACE
870 KBUILD_CFLAGS += $(CC_FLAGS_FTRACE) $(CC_FLAGS_USING)
871 KBUILD_AFLAGS += $(CC_FLAGS_USING)
872 ifdef CONFIG_DYNAMIC_FTRACE
873 ifdef CONFIG_HAVE_C_RECORDMCOUNT
874 BUILD_C_RECORDMCOUNT := y
875 export BUILD_C_RECORDMCOUNT
880 # We trigger additional mismatches with less inlining
881 ifdef CONFIG_DEBUG_SECTION_MISMATCH
882 KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
885 ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
886 KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections
887 LDFLAGS_vmlinux += --gc-sections
890 ifdef CONFIG_SHADOW_CALL_STACK
891 CC_FLAGS_SCS := -fsanitize=shadow-call-stack
892 KBUILD_CFLAGS += $(CC_FLAGS_SCS)
896 # arch Makefile may override CC so keep this after arch Makefile is included
897 NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
899 # warn about C99 declaration after statement
900 KBUILD_CFLAGS += -Wdeclaration-after-statement
902 # Variable Length Arrays (VLAs) should not be used anywhere in the kernel
903 KBUILD_CFLAGS += -Wvla
905 # disable pointer signed / unsigned warnings in gcc 4.0
906 KBUILD_CFLAGS += -Wno-pointer-sign
908 # disable stringop warnings in gcc 8+
909 KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
911 # We'll want to enable this eventually, but it's not going away for 5.7 at least
912 KBUILD_CFLAGS += $(call cc-disable-warning, zero-length-bounds)
913 KBUILD_CFLAGS += $(call cc-disable-warning, array-bounds)
914 KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow)
916 # Another good warning that we'll want to enable eventually
917 KBUILD_CFLAGS += $(call cc-disable-warning, restrict)
919 # Enabled with W=2, disabled by default as noisy
920 KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized)
922 # disable invalid "can't wrap" optimizations for signed / pointers
923 KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow)
925 # clang sets -fmerge-all-constants by default as optimization, but this
926 # is non-conforming behavior for C and in fact breaks the kernel, so we
927 # need to disable it here generally.
928 KBUILD_CFLAGS += $(call cc-option,-fno-merge-all-constants)
930 # for gcc -fno-merge-all-constants disables everything, but it is fine
931 # to have actual conforming behavior enabled.
932 KBUILD_CFLAGS += $(call cc-option,-fmerge-constants)
934 # Make sure -fstack-check isn't enabled (like gentoo apparently did)
935 KBUILD_CFLAGS += $(call cc-option,-fno-stack-check,)
937 # conserve stack if available
938 KBUILD_CFLAGS += $(call cc-option,-fconserve-stack)
940 # Prohibit date/time macros, which would make the build non-deterministic
941 KBUILD_CFLAGS += $(call cc-option,-Werror=date-time)
943 # enforce correct pointer usage
944 KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
946 # Require designated initializers for all marked structures
947 KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
949 # change __FILE__ to the relative path from the srctree
950 KBUILD_CFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
952 # ensure -fcf-protection is disabled when using retpoline as it is
953 # incompatible with -mindirect-branch=thunk-extern
954 ifdef CONFIG_RETPOLINE
955 KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
958 include scripts/Makefile.kasan
959 include scripts/Makefile.extrawarn
960 include scripts/Makefile.ubsan
961 include scripts/Makefile.kcsan
963 # Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
964 KBUILD_CPPFLAGS += $(KCPPFLAGS)
965 KBUILD_AFLAGS += $(KAFLAGS)
966 KBUILD_CFLAGS += $(KCFLAGS)
968 KBUILD_LDFLAGS_MODULE += --build-id
969 LDFLAGS_vmlinux += --build-id
971 ifeq ($(CONFIG_STRIP_ASM_SYMS),y)
972 LDFLAGS_vmlinux += $(call ld-option, -X,)
975 ifeq ($(CONFIG_RELR),y)
976 LDFLAGS_vmlinux += --pack-dyn-relocs=relr
979 # Align the bit size of userspace programs with the kernel
980 KBUILD_USERCFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CFLAGS))
981 KBUILD_USERLDFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CFLAGS))
983 # make the checker run with the right architecture
984 CHECKFLAGS += --arch=$(ARCH)
986 # insure the checker run with the right endianness
987 CHECKFLAGS += $(if $(CONFIG_CPU_BIG_ENDIAN),-mbig-endian,-mlittle-endian)
989 # the checker needs the correct machine size
990 CHECKFLAGS += $(if $(CONFIG_64BIT),-m64,-m32)
992 # Default kernel image to build when no specific target is given.
993 # KBUILD_IMAGE may be overruled on the command line or
994 # set in the environment
995 # Also any assignments in arch/$(ARCH)/Makefile take precedence over
997 export KBUILD_IMAGE ?= vmlinux
1000 # INSTALL_PATH specifies where to place the updated kernel and system map
1001 # images. Default is /boot, but you can set it to other values
1002 export INSTALL_PATH ?= /boot
1005 # INSTALL_DTBS_PATH specifies a prefix for relocations required by build roots.
1006 # Like INSTALL_MOD_PATH, it isn't defined in the Makefile, but can be passed as
1007 # an argument if needed. Otherwise it defaults to the kernel install path
1009 export INSTALL_DTBS_PATH ?= $(INSTALL_PATH)/dtbs/$(KERNELRELEASE)
1012 # INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
1013 # relocations required by build roots. This is not defined in the
1014 # makefile but the argument can be passed to make if needed.
1017 MODLIB = $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
1021 # INSTALL_MOD_STRIP, if defined, will cause modules to be
1022 # stripped after they are installed. If INSTALL_MOD_STRIP is '1', then
1023 # the default option --strip-debug will be used. Otherwise,
1024 # INSTALL_MOD_STRIP value will be used as the options to the strip command.
1026 ifdef INSTALL_MOD_STRIP
1027 ifeq ($(INSTALL_MOD_STRIP),1)
1028 mod_strip_cmd = $(STRIP) --strip-debug
1030 mod_strip_cmd = $(STRIP) $(INSTALL_MOD_STRIP)
1031 endif # INSTALL_MOD_STRIP=1
1033 mod_strip_cmd = true
1034 endif # INSTALL_MOD_STRIP
1035 export mod_strip_cmd
1037 # CONFIG_MODULE_COMPRESS, if defined, will cause module to be compressed
1038 # after they are installed in agreement with CONFIG_MODULE_COMPRESS_GZIP
1039 # or CONFIG_MODULE_COMPRESS_XZ.
1041 mod_compress_cmd = true
1042 ifdef CONFIG_MODULE_COMPRESS
1043 ifdef CONFIG_MODULE_COMPRESS_GZIP
1044 mod_compress_cmd = $(KGZIP) -n -f
1045 endif # CONFIG_MODULE_COMPRESS_GZIP
1046 ifdef CONFIG_MODULE_COMPRESS_XZ
1047 mod_compress_cmd = $(XZ) -f
1048 endif # CONFIG_MODULE_COMPRESS_XZ
1049 endif # CONFIG_MODULE_COMPRESS
1050 export mod_compress_cmd
1052 ifdef CONFIG_MODULE_SIG_ALL
1053 $(eval $(call config_filename,MODULE_SIG_KEY))
1055 mod_sign_cmd = scripts/sign-file $(CONFIG_MODULE_SIG_HASH) $(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY) certs/signing_key.x509
1061 HOST_LIBELF_LIBS = $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
1063 has_libelf = $(call try-run,\
1064 echo "int main() {}" | $(HOSTCC) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)
1066 ifdef CONFIG_STACK_VALIDATION
1067 ifeq ($(has_libelf),1)
1068 objtool_target := tools/objtool FORCE
1070 SKIP_STACK_VALIDATION := 1
1071 export SKIP_STACK_VALIDATION
1075 ifdef CONFIG_DEBUG_INFO_BTF
1076 ifeq ($(has_libelf),1)
1077 resolve_btfids_target := tools/bpf/resolve_btfids FORCE
1079 ERROR_RESOLVE_BTFIDS := 1
1085 export MODORDER := $(extmod-prefix)modules.order
1086 export MODULES_NSDEPS := $(extmod-prefix)modules.nsdeps
1088 ifeq ($(KBUILD_EXTMOD),)
1089 core-y += kernel/ certs/ mm/ fs/ ipc/ security/ crypto/ block/
1091 vmlinux-dirs := $(patsubst %/,%,$(filter %/, \
1092 $(core-y) $(core-m) $(drivers-y) $(drivers-m) \
1093 $(libs-y) $(libs-m)))
1095 vmlinux-alldirs := $(sort $(vmlinux-dirs) Documentation \
1096 $(patsubst %/,%,$(filter %/, $(core-) \
1097 $(drivers-) $(libs-))))
1099 subdir-modorder := $(addsuffix modules.order,$(filter %/, \
1100 $(core-y) $(core-m) $(libs-y) $(libs-m) \
1101 $(drivers-y) $(drivers-m)))
1103 build-dirs := $(vmlinux-dirs)
1104 clean-dirs := $(vmlinux-alldirs)
1106 # Externally visible symbols (used by link-vmlinux.sh)
1107 KBUILD_VMLINUX_OBJS := $(head-y) $(patsubst %/,%/built-in.a, $(core-y))
1108 KBUILD_VMLINUX_OBJS += $(addsuffix built-in.a, $(filter %/, $(libs-y)))
1109 ifdef CONFIG_MODULES
1110 KBUILD_VMLINUX_OBJS += $(patsubst %/, %/lib.a, $(filter %/, $(libs-y)))
1111 KBUILD_VMLINUX_LIBS := $(filter-out %/, $(libs-y))
1113 KBUILD_VMLINUX_LIBS := $(patsubst %/,%/lib.a, $(libs-y))
1115 KBUILD_VMLINUX_OBJS += $(patsubst %/,%/built-in.a, $(drivers-y))
1117 export KBUILD_VMLINUX_OBJS KBUILD_VMLINUX_LIBS
1118 export KBUILD_LDS := arch/$(SRCARCH)/kernel/vmlinux.lds
1119 export LDFLAGS_vmlinux
1120 # used by scripts/Makefile.package
1121 export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) LICENSES arch include scripts tools)
1123 vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)
1125 # Recurse until adjust_autoksyms.sh is satisfied
1126 PHONY += autoksyms_recursive
1127 ifdef CONFIG_TRIM_UNUSED_KSYMS
1128 # For the kernel to actually contain only the needed exported symbols,
1129 # we have to build modules as well to determine what those symbols are.
1130 # (this can be evaluated only once include/config/auto.conf has been included)
1133 autoksyms_recursive: descend modules.order
1134 $(Q)$(CONFIG_SHELL) $(srctree)/scripts/adjust_autoksyms.sh \
1135 "$(MAKE) -f $(srctree)/Makefile vmlinux"
1138 autoksyms_h := $(if $(CONFIG_TRIM_UNUSED_KSYMS), include/generated/autoksyms.h)
1140 quiet_cmd_autoksyms_h = GEN $@
1141 cmd_autoksyms_h = mkdir -p $(dir $@); \
1142 $(CONFIG_SHELL) $(srctree)/scripts/gen_autoksyms.sh $@
1145 $(call cmd,autoksyms_h)
1147 ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
1149 # Final link of vmlinux with optional arch pass after final link
1150 cmd_link-vmlinux = \
1151 $(CONFIG_SHELL) $< $(LD) $(KBUILD_LDFLAGS) $(LDFLAGS_vmlinux) ; \
1152 $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
1154 vmlinux: scripts/link-vmlinux.sh autoksyms_recursive $(vmlinux-deps) FORCE
1155 +$(call if_changed,link-vmlinux)
1159 # The actual objects are generated when descending,
1160 # make sure no implicit rule kicks in
1161 $(sort $(vmlinux-deps) $(subdir-modorder)): descend ;
1163 filechk_kernel.release = \
1164 echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"
1166 # Store (new) KERNELRELEASE string in include/config/kernel.release
1167 include/config/kernel.release: FORCE
1168 $(call filechk,kernel.release)
1170 # Additional helpers built in scripts/
1171 # Carefully list dependencies so we do not try to build scripts twice
1174 scripts: scripts_basic scripts_dtc
1175 $(Q)$(MAKE) $(build)=$(@)
1177 # Things we need to do before we recursively start building the kernel
1178 # or the modules are listed in "prepare".
1179 # A multi level approach is used. prepareN is processed before prepareN-1.
1180 # archprepare is used in arch Makefiles and when processed asm symlink,
1181 # version.h and scripts_basic is processed / created.
1183 PHONY += prepare archprepare
1185 archprepare: outputmakefile archheaders archscripts scripts include/config/kernel.release \
1186 asm-generic $(version_h) $(autoksyms_h) include/generated/utsrelease.h \
1187 include/generated/autoconf.h
1189 prepare0: archprepare
1190 $(Q)$(MAKE) $(build)=scripts/mod
1191 $(Q)$(MAKE) $(build)=.
1193 # All the preparing..
1194 prepare: prepare0 prepare-objtool prepare-resolve_btfids
1196 # Support for using generic headers in asm-generic
1197 asm-generic := -f $(srctree)/scripts/Makefile.asm-generic obj
1199 PHONY += asm-generic uapi-asm-generic
1200 asm-generic: uapi-asm-generic
1201 $(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/asm \
1202 generic=include/asm-generic
1204 $(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/uapi/asm \
1205 generic=include/uapi/asm-generic
1207 PHONY += prepare-objtool prepare-resolve_btfids
1208 prepare-objtool: $(objtool_target)
1209 ifeq ($(SKIP_STACK_VALIDATION),1)
1210 ifdef CONFIG_UNWINDER_ORC
1211 @echo "error: Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
1214 @echo "warning: Cannot use CONFIG_STACK_VALIDATION=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
1218 prepare-resolve_btfids: $(resolve_btfids_target)
1219 ifeq ($(ERROR_RESOLVE_BTFIDS),1)
1220 @echo "error: Cannot resolve BTF IDs for CONFIG_DEBUG_INFO_BTF, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
1223 # Generate some files
1224 # ---------------------------------------------------------------------------
1226 # KERNELRELEASE can change from a few different places, meaning version.h
1227 # needs to be updated, so this check is forced on all builds
1230 define filechk_utsrelease.h
1231 if [ `echo -n "$(KERNELRELEASE)" | wc -c ` -gt $(uts_len) ]; then \
1232 echo '"$(KERNELRELEASE)" exceeds $(uts_len) characters' >&2; \
1235 echo \#define UTS_RELEASE \"$(KERNELRELEASE)\"
1238 define filechk_version.h
1239 echo \#define LINUX_VERSION_CODE $(shell \
1240 expr $(VERSION) \* 65536 + 0$(PATCHLEVEL) \* 256 + 0$(SUBLEVEL)); \
1241 echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))'
1245 $(call filechk,version.h)
1246 $(Q)rm -f $(old_version_h)
1248 include/generated/utsrelease.h: include/config/kernel.release FORCE
1249 $(call filechk,utsrelease.h)
1253 $(Q)find $(srctree)/include/ -name '*.h' | xargs --max-args 1 \
1254 $(srctree)/scripts/headerdep.pl -I$(srctree)/include
1256 # ---------------------------------------------------------------------------
1259 #Default location for installed headers
1260 export INSTALL_HDR_PATH = $(objtree)/usr
1262 quiet_cmd_headers_install = INSTALL $(INSTALL_HDR_PATH)/include
1263 cmd_headers_install = \
1264 mkdir -p $(INSTALL_HDR_PATH); \
1265 rsync -mrl --include='*/' --include='*\.h' --exclude='*' \
1266 usr/include $(INSTALL_HDR_PATH)
1268 PHONY += headers_install
1269 headers_install: headers
1270 $(call cmd,headers_install)
1272 PHONY += archheaders archscripts
1274 hdr-inst := -f $(srctree)/scripts/Makefile.headersinst obj
1277 headers: $(version_h) scripts_unifdef uapi-asm-generic archheaders archscripts
1278 $(if $(wildcard $(srctree)/arch/$(SRCARCH)/include/uapi/asm/Kbuild),, \
1279 $(error Headers not exportable for the $(SRCARCH) architecture))
1280 $(Q)$(MAKE) $(hdr-inst)=include/uapi
1281 $(Q)$(MAKE) $(hdr-inst)=arch/$(SRCARCH)/include/uapi
1283 # Deprecated. It is no-op now.
1284 PHONY += headers_check
1288 ifdef CONFIG_HEADERS_INSTALL
1292 PHONY += scripts_unifdef
1293 scripts_unifdef: scripts_basic
1294 $(Q)$(MAKE) $(build)=scripts scripts/unifdef
1296 # ---------------------------------------------------------------------------
1301 $(Q)$(MAKE) -C $(srctree)/tools/testing/selftests run_tests
1304 $(Q)$(MAKE) -C $(srctree)/tools/testing/selftests $*
1306 PHONY += kselftest-merge
1308 $(if $(wildcard $(objtree)/.config),, $(error No .config exists, config your kernel first!))
1309 $(Q)find $(srctree)/tools/testing/selftests -name config | \
1310 xargs $(srctree)/scripts/kconfig/merge_config.sh -m $(objtree)/.config
1311 $(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
1313 # ---------------------------------------------------------------------------
1316 ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/boot/dts/),)
1317 dtstree := arch/$(SRCARCH)/boot/dts
1322 %.dtb: include/config/kernel.release scripts_dtc
1323 $(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
1325 PHONY += dtbs dtbs_install dtbs_check
1326 dtbs: include/config/kernel.release scripts_dtc
1327 $(Q)$(MAKE) $(build)=$(dtstree)
1329 ifneq ($(filter dtbs_check, $(MAKECMDGOALS)),)
1331 dtbs: dt_binding_check
1337 $(Q)$(MAKE) $(dtbinst)=$(dtstree) dst=$(INSTALL_DTBS_PATH)
1339 ifdef CONFIG_OF_EARLY_FLATTREE
1345 PHONY += scripts_dtc
1346 scripts_dtc: scripts_basic
1347 $(Q)$(MAKE) $(build)=scripts/dtc
1349 ifneq ($(filter dt_binding_check, $(MAKECMDGOALS)),)
1350 export CHECK_DT_BINDING=y
1353 PHONY += dt_binding_check
1354 dt_binding_check: scripts_dtc
1355 $(Q)$(MAKE) $(build)=Documentation/devicetree/bindings
1357 # ---------------------------------------------------------------------------
1360 ifdef CONFIG_MODULES
1362 # By default, build modules as well
1366 # When we're building modules with modversions, we need to consider
1367 # the built-in objects during the descend as well, in order to
1368 # make sure the checksums are up to date before we record them.
1369 ifdef CONFIG_MODVERSIONS
1375 # A module can be listed more than once in obj-m resulting in
1376 # duplicate lines in modules.order files. Those are removed
1377 # using awk while concatenating to the final file.
1380 modules: $(if $(KBUILD_BUILTIN),vmlinux) modules_check
1381 $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
1383 PHONY += modules_check
1384 modules_check: modules.order
1385 $(Q)$(CONFIG_SHELL) $(srctree)/scripts/modules-check.sh $<
1387 cmd_modules_order = $(AWK) '!x[$$0]++' $(real-prereqs) > $@
1389 modules.order: $(subdir-modorder) FORCE
1390 $(call if_changed,modules_order)
1392 targets += modules.order
1394 # Target to prepare building external modules
1395 PHONY += modules_prepare
1396 modules_prepare: prepare
1398 # Target to install modules
1399 PHONY += modules_install
1400 modules_install: _modinst_ _modinst_post
1404 @rm -rf $(MODLIB)/kernel
1405 @rm -f $(MODLIB)/source
1406 @mkdir -p $(MODLIB)/kernel
1407 @ln -s $(abspath $(srctree)) $(MODLIB)/source
1408 @if [ ! $(objtree) -ef $(MODLIB)/build ]; then \
1409 rm -f $(MODLIB)/build ; \
1410 ln -s $(CURDIR) $(MODLIB)/build ; \
1412 @sed 's:^:kernel/:' modules.order > $(MODLIB)/modules.order
1413 @cp -f modules.builtin $(MODLIB)/
1414 @cp -f $(objtree)/modules.builtin.modinfo $(MODLIB)/
1415 $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst
1417 # This depmod is only for convenience to give the initial
1418 # boot a modules.dep even before / is mounted read-write. However the
1419 # boot script depmod is the master version.
1420 PHONY += _modinst_post
1421 _modinst_post: _modinst_
1424 ifeq ($(CONFIG_MODULE_SIG), y)
1425 PHONY += modules_sign
1427 $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modsign
1430 else # CONFIG_MODULES
1432 # Modules not configured
1433 # ---------------------------------------------------------------------------
1435 PHONY += modules modules_install
1436 modules modules_install:
1438 @echo >&2 "The present kernel configuration has modules disabled."
1439 @echo >&2 "Type 'make config' and enable loadable module support."
1440 @echo >&2 "Then build a kernel with module support enabled."
1444 endif # CONFIG_MODULES
1447 # Cleaning is done on three levels.
1448 # make clean Delete most generated files
1449 # Leave enough to build external modules
1450 # make mrproper Delete the current configuration, and all generated files
1451 # make distclean Remove editor backup files, patch leftover files and the like
1453 # Directories & files removed with 'make clean'
1454 CLEAN_FILES += include/ksym vmlinux.symvers \
1455 modules.builtin modules.builtin.modinfo modules.nsdeps
1457 # Directories & files removed with 'make mrproper'
1458 MRPROPER_FILES += include/config include/generated \
1459 arch/$(SRCARCH)/include/generated .tmp_objdiff \
1460 debian snap tar-install \
1461 .config .config.old .version \
1463 signing_key.pem signing_key.priv signing_key.x509 \
1464 x509.genkey extra_certificates signing_key.x509.keyid \
1465 signing_key.x509.signer vmlinux-gdb.py \
1468 # Directories & files removed with 'make distclean'
1469 DISTCLEAN_FILES += tags TAGS cscope* GPATH GTAGS GRTAGS GSYMS
1471 # clean - Delete most, but leave enough to build external modules
1473 clean: rm-files := $(CLEAN_FILES)
1475 PHONY += archclean vmlinuxclean
1478 $(Q)$(CONFIG_SHELL) $(srctree)/scripts/link-vmlinux.sh clean
1479 $(Q)$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) clean)
1481 clean: archclean vmlinuxclean
1483 # mrproper - Delete all generated files, including .config
1485 mrproper: rm-files := $(wildcard $(MRPROPER_FILES))
1486 mrproper-dirs := $(addprefix _mrproper_,scripts)
1488 PHONY += $(mrproper-dirs) mrproper
1490 $(Q)$(MAKE) $(clean)=$(patsubst _mrproper_%,%,$@)
1492 mrproper: clean $(mrproper-dirs)
1497 distclean: rm-files := $(wildcard $(DISTCLEAN_FILES))
1503 @find $(srctree) $(RCS_FIND_IGNORE) \
1504 \( -name '*.orig' -o -name '*.rej' -o -name '*~' \
1505 -o -name '*.bak' -o -name '#*#' -o -name '*%' \
1506 -o -name 'core' \) \
1507 -type f -print | xargs rm -f
1510 # Packaging of the kernel to various formats
1511 # ---------------------------------------------------------------------------
1514 $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.package $@
1515 %pkg: include/config/kernel.release FORCE
1516 $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.package $@
1518 # Brief documentation of the typical targets used
1519 # ---------------------------------------------------------------------------
1521 boards := $(wildcard $(srctree)/arch/$(SRCARCH)/configs/*_defconfig)
1522 boards := $(sort $(notdir $(boards)))
1523 board-dirs := $(dir $(wildcard $(srctree)/arch/$(SRCARCH)/configs/*/*_defconfig))
1524 board-dirs := $(sort $(notdir $(board-dirs:/=)))
1528 @echo 'Cleaning targets:'
1529 @echo ' clean - Remove most generated files but keep the config and'
1530 @echo ' enough build support to build external modules'
1531 @echo ' mrproper - Remove all generated files + config + various backup files'
1532 @echo ' distclean - mrproper + remove editor backup and patch files'
1534 @echo 'Configuration targets:'
1535 @$(MAKE) -f $(srctree)/scripts/kconfig/Makefile help
1537 @echo 'Other generic targets:'
1538 @echo ' all - Build all targets marked with [*]'
1539 @echo '* vmlinux - Build the bare kernel'
1540 @echo '* modules - Build all modules'
1541 @echo ' modules_install - Install all modules to INSTALL_MOD_PATH (default: /)'
1542 @echo ' dir/ - Build all files in dir and below'
1543 @echo ' dir/file.[ois] - Build specified target only'
1544 @echo ' dir/file.ll - Build the LLVM assembly file'
1545 @echo ' (requires compiler support for LLVM assembly generation)'
1546 @echo ' dir/file.lst - Build specified mixed source/assembly target only'
1547 @echo ' (requires a recent binutils and recent build (System.map))'
1548 @echo ' dir/file.ko - Build module including final link'
1549 @echo ' modules_prepare - Set up for building external modules'
1550 @echo ' tags/TAGS - Generate tags file for editors'
1551 @echo ' cscope - Generate cscope index'
1552 @echo ' gtags - Generate GNU GLOBAL index'
1553 @echo ' kernelrelease - Output the release version string (use with make -s)'
1554 @echo ' kernelversion - Output the version stored in Makefile (use with make -s)'
1555 @echo ' image_name - Output the image name (use with make -s)'
1556 @echo ' headers_install - Install sanitised kernel headers to INSTALL_HDR_PATH'; \
1557 echo ' (default: $(INSTALL_HDR_PATH))'; \
1559 @echo 'Static analysers:'
1560 @echo ' checkstack - Generate a list of stack hogs'
1561 @echo ' namespacecheck - Name space analysis on compiled kernel'
1562 @echo ' versioncheck - Sanity check on version.h usage'
1563 @echo ' includecheck - Check for duplicate included header files'
1564 @echo ' export_report - List the usages of all exported symbols'
1565 @echo ' headerdep - Detect inclusion cycles in headers'
1566 @echo ' coccicheck - Check with Coccinelle'
1569 @echo ' nsdeps - Generate missing symbol namespace dependencies'
1571 @echo 'Kernel selftest:'
1572 @echo ' kselftest - Build and run kernel selftest'
1573 @echo ' Build, install, and boot kernel before'
1574 @echo ' running kselftest on it'
1575 @echo ' Run as root for full coverage'
1576 @echo ' kselftest-all - Build kernel selftest'
1577 @echo ' kselftest-install - Build and install kernel selftest'
1578 @echo ' kselftest-clean - Remove all generated kselftest files'
1579 @echo ' kselftest-merge - Merge all the config dependencies of'
1580 @echo ' kselftest to existing .config.'
1583 echo 'Devicetree:'; \
1584 echo '* dtbs - Build device tree blobs for enabled boards'; \
1585 echo ' dtbs_install - Install dtbs to $(INSTALL_DTBS_PATH)'; \
1586 echo ' dt_binding_check - Validate device tree binding documents'; \
1587 echo ' dtbs_check - Validate device tree source files';\
1590 @echo 'Userspace tools targets:'
1591 @echo ' use "make tools/help"'
1592 @echo ' or "cd tools; make help"'
1594 @echo 'Kernel packaging:'
1595 @$(MAKE) -f $(srctree)/scripts/Makefile.package help
1597 @echo 'Documentation targets:'
1598 @$(MAKE) -f $(srctree)/Documentation/Makefile dochelp
1600 @echo 'Architecture specific targets ($(SRCARCH)):'
1601 @$(if $(archhelp),$(archhelp),\
1602 echo ' No architecture specific help defined for $(SRCARCH)')
1605 $(foreach b, $(boards), \
1606 printf " %-27s - Build for %s\\n" $(b) $(subst _defconfig,,$(b));) \
1608 @$(if $(board-dirs), \
1609 $(foreach b, $(board-dirs), \
1610 printf " %-16s - Show %s-specific targets\\n" help-$(b) $(b);) \
1611 printf " %-16s - Show all of the above\\n" help-boards; \
1614 @echo ' make V=0|1 [targets] 0 => quiet build (default), 1 => verbose build'
1615 @echo ' make V=2 [targets] 2 => give reason for rebuild of target'
1616 @echo ' make O=dir [targets] Locate all output files in "dir", including .config'
1617 @echo ' make C=1 [targets] Check re-compiled c source with $$CHECK'
1618 @echo ' (sparse by default)'
1619 @echo ' make C=2 [targets] Force check of all c source with $$CHECK'
1620 @echo ' make RECORDMCOUNT_WARN=1 [targets] Warn about ignored mcount sections'
1621 @echo ' make W=n [targets] Enable extra build checks, n=1,2,3 where'
1622 @echo ' 1: warnings which may be relevant and do not occur too often'
1623 @echo ' 2: warnings which occur quite often but may still be relevant'
1624 @echo ' 3: more obscure warnings, can most likely be ignored'
1625 @echo ' Multiple levels can be combined with W=12 or W=123'
1627 @echo 'Execute "make" or "make all" to build all targets marked with [*] '
1628 @echo 'For further info see the ./README file'
1631 help-board-dirs := $(addprefix help-,$(board-dirs))
1633 help-boards: $(help-board-dirs)
1635 boards-per-dir = $(sort $(notdir $(wildcard $(srctree)/arch/$(SRCARCH)/configs/$*/*_defconfig)))
1637 $(help-board-dirs): help-%:
1638 @echo 'Architecture specific targets ($(SRCARCH) $*):'
1639 @$(if $(boards-per-dir), \
1640 $(foreach b, $(boards-per-dir), \
1641 printf " %-24s - Build for %s\\n" $*/$(b) $(subst _defconfig,,$(b));) \
1645 # Documentation targets
1646 # ---------------------------------------------------------------------------
1647 DOC_TARGETS := xmldocs latexdocs pdfdocs htmldocs epubdocs cleandocs \
1648 linkcheckdocs dochelp refcheckdocs
1649 PHONY += $(DOC_TARGETS)
1651 $(Q)$(MAKE) $(build)=Documentation $@
1654 # ---------------------------------------------------------------------------
1656 PHONY += scripts_gdb
1657 scripts_gdb: prepare0
1658 $(Q)$(MAKE) $(build)=scripts/gdb
1659 $(Q)ln -fsn $(abspath $(srctree)/scripts/gdb/vmlinux-gdb.py)
1661 ifdef CONFIG_GDB_SCRIPTS
1665 else # KBUILD_EXTMOD
1668 # External module support.
1669 # When building external modules the kernel used as basis is considered
1670 # read-only, and no consistency checks are made and the make
1671 # system is not used on the basis kernel. If updates are required
1672 # in the basis kernel ordinary make commands (without M=...) must
1675 # The following are the only valid targets when building external
1677 # make M=dir clean Delete all automatically generated files
1678 # make M=dir modules Make all modules in specified dir
1679 # make M=dir Same as 'make M=dir modules'
1680 # make M=dir modules_install
1681 # Install the modules built in the module directory
1682 # Assumes install directory is already created
1684 # We are always building modules
1687 build-dirs := $(KBUILD_EXTMOD)
1690 $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
1692 PHONY += modules_install
1693 modules_install: _emodinst_ _emodinst_post
1695 install-dir := $(if $(INSTALL_MOD_DIR),$(INSTALL_MOD_DIR),extra)
1698 $(Q)mkdir -p $(MODLIB)/$(install-dir)
1699 $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst
1701 PHONY += _emodinst_post
1702 _emodinst_post: _emodinst_
1705 clean-dirs := $(KBUILD_EXTMOD)
1706 clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers $(KBUILD_EXTMOD)/modules.nsdeps
1710 @echo ' Building external modules.'
1711 @echo ' Syntax: make -C path/to/kernel/src M=$$PWD target'
1713 @echo ' modules - default target, build the module(s)'
1714 @echo ' modules_install - install the module'
1715 @echo ' clean - remove generated files in module directory only'
1719 endif # KBUILD_EXTMOD
1722 # ---------------------------------------------------------------------------
1723 # To build individual files in subdirectories, you can do like this:
1725 # make foo/bar/baz.s
1727 # The supported suffixes for single-target are listed in 'single-targets'
1729 # To build only under specific subdirectories, you can do like this:
1735 # .ko is special because modpost is needed
1736 single-ko := $(sort $(filter %.ko, $(MAKECMDGOALS)))
1737 single-no-ko := $(sort $(patsubst %.ko,%.mod, $(MAKECMDGOALS)))
1739 $(single-ko): single_modpost
1741 $(single-no-ko): descend
1744 ifeq ($(KBUILD_EXTMOD),)
1745 # For the single build of in-tree modules, use a temporary file to avoid
1746 # the situation of modules_install installing an invalid modules.order.
1747 MODORDER := .modules.tmp
1750 PHONY += single_modpost
1751 single_modpost: $(single-no-ko)
1752 $(Q){ $(foreach m, $(single-ko), echo $(extmod-prefix)$m;) } > $(MODORDER)
1753 $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
1757 export KBUILD_SINGLE_TARGETS := $(addprefix $(extmod-prefix), $(single-no-ko))
1759 # trim unrelated directories
1760 build-dirs := $(foreach d, $(build-dirs), \
1761 $(if $(filter $(d)/%, $(KBUILD_SINGLE_TARGETS)), $(d)))
1765 ifndef CONFIG_MODULES
1769 # Handle descending into subdirectories listed in $(build-dirs)
1770 # Preset locale variables to speed up the build process. Limit locale
1771 # tweaks to this spot to avoid wrong language settings when running
1772 # make menuconfig etc.
1773 # Error messages still appears in the original language
1774 PHONY += descend $(build-dirs)
1775 descend: $(build-dirs)
1776 $(build-dirs): prepare
1777 $(Q)$(MAKE) $(build)=$@ \
1778 single-build=$(if $(filter-out $@/, $(filter $@/%, $(KBUILD_SINGLE_TARGETS))),1) \
1779 need-builtin=1 need-modorder=1
1781 clean-dirs := $(addprefix _clean_, $(clean-dirs))
1782 PHONY += $(clean-dirs) clean
1784 $(Q)$(MAKE) $(clean)=$(patsubst _clean_%,%,$@)
1786 clean: $(clean-dirs)
1788 @find $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
1789 \( -name '*.[aios]' -o -name '*.ko' -o -name '.*.cmd' \
1791 -o -name '*.dtb' -o -name '*.dtb.S' -o -name '*.dt.yaml' \
1792 -o -name '*.dwo' -o -name '*.lst' \
1793 -o -name '*.su' -o -name '*.mod' \
1794 -o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
1795 -o -name '*.lex.c' -o -name '*.tab.[ch]' \
1796 -o -name '*.asn1.[ch]' \
1797 -o -name '*.symtypes' -o -name 'modules.order' \
1798 -o -name '.tmp_*.o.*' \
1799 -o -name '*.c.[012]*.*' \
1801 -o -name '*.gcno' \) -type f -print | xargs rm -f
1803 # Generate tags for editors
1804 # ---------------------------------------------------------------------------
1805 quiet_cmd_tags = GEN $@
1806 cmd_tags = $(BASH) $(srctree)/scripts/tags.sh $@
1808 tags TAGS cscope gtags: FORCE
1811 # Script to generate missing namespace dependencies
1812 # ---------------------------------------------------------------------------
1815 nsdeps: export KBUILD_NSDEPS=1
1817 $(Q)$(CONFIG_SHELL) $(srctree)/scripts/nsdeps
1819 # Scripts to check various things for consistency
1820 # ---------------------------------------------------------------------------
1822 PHONY += includecheck versioncheck coccicheck namespacecheck export_report
1825 find $(srctree)/* $(RCS_FIND_IGNORE) \
1826 -name '*.[hcS]' -type f -print | sort \
1827 | xargs $(PERL) -w $(srctree)/scripts/checkincludes.pl
1830 find $(srctree)/* $(RCS_FIND_IGNORE) \
1831 -name '*.[hcS]' -type f -print | sort \
1832 | xargs $(PERL) -w $(srctree)/scripts/checkversion.pl
1835 $(Q)$(BASH) $(srctree)/scripts/$@
1838 $(PERL) $(srctree)/scripts/namespace.pl
1841 $(PERL) $(srctree)/scripts/export_report.pl
1843 PHONY += checkstack kernelrelease kernelversion image_name
1845 # UML needs a little special treatment here. It wants to use the host
1846 # toolchain, so needs $(SUBARCH) passed to checkstack.pl. Everyone
1847 # else wants $(ARCH), including people doing cross-builds, which means
1848 # that $(SUBARCH) doesn't work here.
1850 CHECKSTACK_ARCH := $(SUBARCH)
1852 CHECKSTACK_ARCH := $(ARCH)
1855 $(OBJDUMP) -d vmlinux $$(find . -name '*.ko') | \
1856 $(PERL) $(srctree)/scripts/checkstack.pl $(CHECKSTACK_ARCH)
1859 @echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"
1862 @echo $(KERNELVERSION)
1865 @echo $(KBUILD_IMAGE)
1867 # Clear a bunch of variables before executing the submake
1869 ifeq ($(quiet),silent_)
1874 $(Q)mkdir -p $(objtree)/tools
1875 $(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(tools_silent) $(filter --j% -j,$(MAKEFLAGS))" O=$(abspath $(objtree)) subdir=tools -C $(srctree)/tools/
1878 $(Q)mkdir -p $(objtree)/tools
1879 $(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(tools_silent) $(filter --j% -j,$(MAKEFLAGS))" O=$(abspath $(objtree)) subdir=tools -C $(srctree)/tools/ $*
1881 quiet_cmd_rmfiles = $(if $(wildcard $(rm-files)),CLEAN $(wildcard $(rm-files)))
1882 cmd_rmfiles = rm -rf $(rm-files)
1884 # Run depmod only if we have System.map and depmod is executable
1885 quiet_cmd_depmod = DEPMOD $(KERNELRELEASE)
1886 cmd_depmod = $(CONFIG_SHELL) $(srctree)/scripts/depmod.sh $(DEPMOD) \
1889 # read saved command lines for existing targets
1890 existing-targets := $(wildcard $(sort $(targets)))
1892 -include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
1894 endif # config-build
1896 endif # need-sub-make
1901 # Declare the contents of the PHONY variable as phony. We keep that
1902 # information in a variable so we can use it in if_changed and friends.