64 KiB
SPDX-License-Identifier: GPL-2.0
VERSION = 6 PATCHLEVEL = 0 SUBLEVEL = 0 EXTRAVERSION = -rc7 NAME = Hurr durr I'ma ninja sloth
DOCUMENTATION
To see a list of typical targets execute "make help"
More info can be located in ./README
Comments in this file are targeted only to the developer, do not
expect to learn how to build the kernel reading this file.
$(if $(filter %, $(MAKECMDGOALS)),
$(error targets prefixed with '' are only for internal use))
That's our default target when none is given on the command line
PHONY := __all __all:
We are using a recursive build, so we need to do a little thinking
to get the ordering right.
Most importantly: sub-Makefiles should only ever modify files in
their own directory. If in some directory we have a dependency on
a file in another dir (which doesn't happen often, but it's often
unavoidable when linking the built-in.a targets which finally
turn into vmlinux), we will call a sub make in that other dir, and
after that we are sure that everything which is in that other dir
is now up to date.
The only cases where we need to modify files which have global
effects are thus separated out and done before the recursive
descending is started. They are now explicitly listed as the
prepare rule.
ifneq ($(sub_make_done),1)
Do not use make's built-in rules and variables
(this increases performance and avoids hard-to-debug behaviour)
MAKEFLAGS += -rR
Avoid funny character set dependencies
unexport LC_ALL LC_COLLATE=C LC_NUMERIC=C export LC_COLLATE LC_NUMERIC
Avoid interference with shell env settings
unexport GREP_OPTIONS
Beautify output
---------------------------------------------------------------------------
Normally, we echo the whole command before executing it. By making
that echo $($(quiet)$(cmd)), we now have the possibility to set
$(quiet) to choose other forms of output instead, e.g.
quiet_cmd_cc_o_c = Compiling $(RELDIR)/$@
cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
If $(quiet) is empty, the whole command will be printed.
If it is set to "quiet_", only the short version will be printed.
If it is set to "silent_", nothing will be printed at all, since
the variable $(silent_cmd_cc_o_c) doesn't exist.
A simple variant is to prefix commands with $(Q) - that's useful
for commands that shall be hidden in non-verbose mode.
$(Q)ln $@ :<
If KBUILD_VERBOSE equals 0 then the above command will be hidden.
If KBUILD_VERBOSE equals 1 then the above command is displayed.
If KBUILD_VERBOSE equals 2 then give the reason why each target is rebuilt.
To put more focus on warnings, be less verbose as default
Use 'make V=1' to see the full commands
ifeq ("$(origin V)", "command line") KBUILD_VERBOSE = $(V) endif ifndef KBUILD_VERBOSE KBUILD_VERBOSE = 0 endif
ifeq ($(KBUILD_VERBOSE),1) quiet = Q = else quiet=quiet_ Q = @ endif
If the user is running make -s (silent mode), suppress echoing of
commands
ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),) quiet=silent_ KBUILD_VERBOSE = 0 endif
export quiet Q KBUILD_VERBOSE
Call a source code checker (by default, "sparse") as part of the
C compilation.
Use 'make C=1' to enable checking of only re-compiled files.
Use 'make C=2' to enable checking of all source files, regardless
of whether they are re-compiled or not.
See the file "Documentation/dev-tools/sparse.rst" for more details,
including where to get the "sparse" utility.
ifeq ("$(origin C)", "command line") KBUILD_CHECKSRC = $(C) endif ifndef KBUILD_CHECKSRC KBUILD_CHECKSRC = 0 endif
export KBUILD_CHECKSRC
Use make M=dir or set the environment variable KBUILD_EXTMOD to specify the
directory of external module to build. Setting M= takes precedence.
ifeq ("$(origin M)", "command line") KBUILD_EXTMOD := $(M) endif
$(if $(word 2, $(KBUILD_EXTMOD)),
$(error building multiple external modules is not supported))
$(foreach x, % :, $(if $(findstring $x, $(KBUILD_EXTMOD)),
$(error module directory path cannot contain '$x')))
Remove trailing slashes
ifneq ($(filter %/, $(KBUILD_EXTMOD)),) KBUILD_EXTMOD := $(shell dirname $(KBUILD_EXTMOD).) endif
export KBUILD_EXTMOD
Kbuild will save output files in the current working directory.
This does not need to match to the root of the kernel source tree.
For example, you can do this:
cd /dir/to/store/output/files; make -f /dir/to/kernel/source/Makefile
If you want to save output files in a different location, there are
two syntaxes to specify it.
1) O=
Use "make O=dir/to/store/output/files/"
2) Set KBUILD_OUTPUT
Set the environment variable KBUILD_OUTPUT to point to the output directory.
export KBUILD_OUTPUT=dir/to/store/output/files/; make
The O= assignment takes precedence over the KBUILD_OUTPUT environment
variable.
Do we want to change the working directory?
ifeq ("$(origin O)", "command line") KBUILD_OUTPUT := $(O) endif
ifneq ($(KBUILD_OUTPUT),)
Make's built-in functions such as $(abspath ...), $(realpath ...) cannot
expand a shell special character '~'. We use a somewhat tedious way here.
abs_objtree := $(shell mkdir -p $(KBUILD_OUTPUT) && cd $(KBUILD_OUTPUT) && pwd)
$(if $(abs_objtree),,
$(error failed to create output directory "$(KBUILD_OUTPUT)"))
$(realpath ...) resolves symlinks
abs_objtree := $(realpath $(abs_objtree)) else abs_objtree := $(CURDIR) endif # ifneq ($(KBUILD_OUTPUT),)
ifeq ($(abs_objtree),$(CURDIR))
Suppress "Entering directory ..." unless we are changing the work directory.
MAKEFLAGS += --no-print-directory else need-sub-make := 1 endif
this-makefile := $(lastword $(MAKEFILE_LIST)) abs_srctree := $(realpath $(dir $(this-makefile)))
ifneq ($(words $(subst :, ,$(abs_srctree))), 1) $(error source directory cannot contain spaces or colons) endif
ifneq ($(abs_srctree),$(abs_objtree))
Look for make include files relative to root of kernel src
--included-dir is added for backward compatibility, but you should not rely on
it. Please add $(srctree)/ prefix to include Makefiles in the source tree.
MAKEFLAGS += --include-dir=$(abs_srctree) endif
ifneq ($(filter 3.%,$(MAKE_VERSION)),)
'MAKEFLAGS += -rR' does not immediately become effective for GNU Make 3.x
We need to invoke sub-make to avoid implicit rules in the top Makefile.
need-sub-make := 1
Cancel implicit rules for this Makefile.
$(this-makefile): ; endif
export abs_srctree abs_objtree export sub_make_done := 1
ifeq ($(need-sub-make),1)
PHONY += $(MAKECMDGOALS) __sub-make
$(filter-out $(this-makefile), $(MAKECMDGOALS)) __all: __sub-make @:
Invoke a second make in the output directory, passing relevant variables
__sub-make: $(Q)$(MAKE) -C $(abs_objtree) -f $(abs_srctree)/Makefile $(MAKECMDGOALS)
endif # need-sub-make endif # sub_make_done
We process the rest of the Makefile if this is the final invocation of make
ifeq ($(need-sub-make),)
Do not print "Entering directory ...",
but we want to display it when entering to the output directory
so that IDEs/editors are able to understand relative filenames.
MAKEFLAGS += --no-print-directory
ifeq ($(abs_srctree),$(abs_objtree)) # building in the source tree srctree := . building_out_of_srctree := else ifeq ($(abs_srctree)/,$(dir $(abs_objtree))) # building in a subdirectory of the source tree srctree := .. else srctree := $(abs_srctree) endif building_out_of_srctree := 1 endif
ifneq ($(KBUILD_ABS_SRCTREE),) srctree := $(abs_srctree) endif
objtree := . VPATH := $(srctree)
export building_out_of_srctree srctree objtree VPATH
To make sure we do not include .config for any of the *config targets
catch them early, and hand them over to scripts/kconfig/Makefile
It is allowed to specify more targets when calling make, including
mixing *config targets and build targets.
For example 'make oldconfig all'.
Detect when mixed targets is specified, and make a second invocation
of make so .config is not included in this case either (for *config).
version_h := include/generated/uapi/linux/version.h
clean-targets := %clean mrproper cleandocs
no-dot-config-targets := $(clean-targets)
cscope gtags TAGS tags help% %docs check% coccicheck
$(version_h) headers headers_% archheaders archscripts
%asm-generic kernelversion %src-pkg dt_binding_check
outputmakefile
Installation targets should not require compiler. Unfortunately, vdso_install
is an exception where build artifacts may be updated. This must be fixed.
no-compiler-targets := $(no-dot-config-targets) install dtbs_install
headers_install modules_install kernelrelease image_name
no-sync-config-targets := $(no-dot-config-targets) %install kernelrelease
image_name
single-targets := %.a %.i %.ko %.lds %.ll %.lst %.mod %.o %.s %.symtypes %/
config-build := mixed-build := need-config := 1 need-compiler := 1 may-sync-config := 1 single-build :=
ifneq ($(filter $(no-dot-config-targets), $(MAKECMDGOALS)),) ifeq ($(filter-out $(no-dot-config-targets), $(MAKECMDGOALS)),) need-config := endif endif
ifneq ($(filter $(no-compiler-targets), $(MAKECMDGOALS)),) ifeq ($(filter-out $(no-compiler-targets), $(MAKECMDGOALS)),) need-compiler := endif endif
ifneq ($(filter $(no-sync-config-targets), $(MAKECMDGOALS)),) ifeq ($(filter-out $(no-sync-config-targets), $(MAKECMDGOALS)),) may-sync-config := endif endif
ifneq ($(KBUILD_EXTMOD),) may-sync-config := endif
ifeq ($(KBUILD_EXTMOD),) ifneq ($(filter %config,$(MAKECMDGOALS)),) config-build := 1 ifneq ($(words $(MAKECMDGOALS)),1) mixed-build := 1 endif endif endif
We cannot build single targets and the others at the same time
ifneq ($(filter $(single-targets), $(MAKECMDGOALS)),) single-build := 1 ifneq ($(filter-out $(single-targets), $(MAKECMDGOALS)),) mixed-build := 1 endif endif
For "make -j clean all", "make -j mrproper defconfig all", etc.
ifneq ($(filter $(clean-targets),$(MAKECMDGOALS)),) ifneq ($(filter-out $(clean-targets),$(MAKECMDGOALS)),) mixed-build := 1 endif endif
install and modules_install need also be processed one by one
ifneq ($(filter install,$(MAKECMDGOALS)),) ifneq ($(filter modules_install,$(MAKECMDGOALS)),) mixed-build := 1 endif endif
ifdef mixed-build
===========================================================================
We're called with mixed targets (*config and build targets).
Handle them one by one.
PHONY += $(MAKECMDGOALS) __build_one_by_one
$(MAKECMDGOALS): __build_one_by_one @:
__build_one_by_one:
$(Q)set -e;
for i in $(MAKECMDGOALS); do
$(MAKE) -f $(srctree)/Makefile $$i;
done
else # !mixed-build
include $(srctree)/scripts/Kbuild.include
Read KERNELRELEASE from include/config/kernel.release (if it exists)
KERNELRELEASE = $(shell cat include/config/kernel.release 2> /dev/null) KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION) export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION
include $(srctree)/scripts/subarch.include
Cross compiling and selecting different set of gcc/bin-utils
---------------------------------------------------------------------------
When performing cross compilation for other architectures ARCH shall be set
to the target architecture. (See arch/* for the possibilities).
ARCH can be set during invocation of make:
make ARCH=ia64
Another way is to have ARCH set in the environment.
The default ARCH is the host where make is executed.
CROSS_COMPILE specify the prefix used for all executables used
during compilation. Only gcc and related bin-utils executables
are prefixed with $(CROSS_COMPILE).
CROSS_COMPILE can be set on the command line
make CROSS_COMPILE=ia64-linux-
Alternatively CROSS_COMPILE can be set in the environment.
Default value for CROSS_COMPILE is not to prefix executables
Note: Some architectures assign CROSS_COMPILE in their arch/*/Makefile
ARCH ?= $(SUBARCH)
Architecture as present in compile.h
UTS_MACHINE := $(ARCH) SRCARCH := $(ARCH)
Additional ARCH settings for x86
ifeq ($(ARCH),i386) SRCARCH := x86 endif ifeq ($(ARCH),x86_64) SRCARCH := x86 endif
Additional ARCH settings for sparc
ifeq ($(ARCH),sparc32) SRCARCH := sparc endif ifeq ($(ARCH),sparc64) SRCARCH := sparc endif
Additional ARCH settings for parisc
ifeq ($(ARCH),parisc64) SRCARCH := parisc endif
export cross_compiling := ifneq ($(SRCARCH),$(SUBARCH)) cross_compiling := 1 endif
KCONFIG_CONFIG ?= .config export KCONFIG_CONFIG
SHELL used by kbuild
CONFIG_SHELL := sh
HOST_LFS_CFLAGS := $(shell getconf LFS_CFLAGS 2>/dev/null) HOST_LFS_LDFLAGS := $(shell getconf LFS_LDFLAGS 2>/dev/null) HOST_LFS_LIBS := $(shell getconf LFS_LIBS 2>/dev/null)
ifneq ($(LLVM),) ifneq ($(filter %/,$(LLVM)),) LLVM_PREFIX := $(LLVM) else ifneq ($(filter -%,$(LLVM)),) LLVM_SUFFIX := $(LLVM) endif
HOSTCC = $(LLVM_PREFIX)clang$(LLVM_SUFFIX) HOSTCXX = $(LLVM_PREFIX)clang++$(LLVM_SUFFIX) else HOSTCC = gcc HOSTCXX = g++ endif HOSTPKG_CONFIG = pkg-config
KBUILD_USERHOSTCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes
-O2 -fomit-frame-pointer -std=gnu11
-Wdeclaration-after-statement
KBUILD_USERCFLAGS := $(KBUILD_USERHOSTCFLAGS) $(USERCFLAGS)
KBUILD_USERLDFLAGS := $(USERLDFLAGS)
KBUILD_HOSTCFLAGS := $(KBUILD_USERHOSTCFLAGS) $(HOST_LFS_CFLAGS) $(HOSTCFLAGS) KBUILD_HOSTCXXFLAGS := -Wall -O2 $(HOST_LFS_CFLAGS) $(HOSTCXXFLAGS) KBUILD_HOSTLDFLAGS := $(HOST_LFS_LDFLAGS) $(HOSTLDFLAGS) KBUILD_HOSTLDLIBS := $(HOST_LFS_LIBS) $(HOSTLDLIBS)
Make variables (CC, etc...)
CPP = $(CC) -E ifneq ($(LLVM),) CC = $(LLVM_PREFIX)clang$(LLVM_SUFFIX) LD = $(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX) AR = $(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX) NM = $(LLVM_PREFIX)llvm-nm$(LLVM_SUFFIX) OBJCOPY = $(LLVM_PREFIX)llvm-objcopy$(LLVM_SUFFIX) OBJDUMP = $(LLVM_PREFIX)llvm-objdump$(LLVM_SUFFIX) READELF = $(LLVM_PREFIX)llvm-readelf$(LLVM_SUFFIX) STRIP = $(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX) else CC = $(CROSS_COMPILE)gcc LD = $(CROSS_COMPILE)ld AR = $(CROSS_COMPILE)ar NM = $(CROSS_COMPILE)nm OBJCOPY = $(CROSS_COMPILE)objcopy OBJDUMP = $(CROSS_COMPILE)objdump READELF = $(CROSS_COMPILE)readelf STRIP = $(CROSS_COMPILE)strip endif PAHOLE = pahole RESOLVE_BTFIDS = $(objtree)/tools/bpf/resolve_btfids/resolve_btfids LEX = flex YACC = bison AWK = awk INSTALLKERNEL := installkernel DEPMOD = depmod PERL = perl PYTHON3 = python3 CHECK = sparse BASH = bash KGZIP = gzip KBZIP2 = bzip2 KLZOP = lzop LZMA = lzma LZ4 = lz4c XZ = xz ZSTD = zstd
PAHOLE_FLAGS = $(shell PAHOLE=$(PAHOLE) $(srctree)/scripts/pahole-flags.sh)
CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__
-Wbitwise -Wno-return-void -Wno-unknown-attribute $(CF)
NOSTDINC_FLAGS :=
CFLAGS_MODULE =
AFLAGS_MODULE =
LDFLAGS_MODULE =
CFLAGS_KERNEL =
AFLAGS_KERNEL =
LDFLAGS_vmlinux =
Use USERINCLUDE when you must reference the UAPI directories only.
USERINCLUDE :=
-I$(srctree)/arch/$(SRCARCH)/include/uapi
-I$(objtree)/arch/$(SRCARCH)/include/generated/uapi
-I$(srctree)/include/uapi
-I$(objtree)/include/generated/uapi
-include $(srctree)/include/linux/compiler-version.h
-include $(srctree)/include/linux/kconfig.h
Use LINUXINCLUDE when you must reference the include/ directory.
Needed to be compatible with the O= option
LINUXINCLUDE :=
-I$(srctree)/arch/$(SRCARCH)/include
-I$(objtree)/arch/$(SRCARCH)/include/generated
$(if $(building_out_of_srctree),-I$(srctree)/include)
-I$(objtree)/include
$(USERINCLUDE)
KBUILD_AFLAGS := -D__ASSEMBLY__ -fno-PIE
KBUILD_CFLAGS := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs
-fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE
-Werror=implicit-function-declaration -Werror=implicit-int
-Werror=return-type -Wno-format-security
-std=gnu11
KBUILD_CPPFLAGS := -D__KERNEL__
KBUILD_AFLAGS_KERNEL :=
KBUILD_CFLAGS_KERNEL :=
KBUILD_AFLAGS_MODULE := -DMODULE
KBUILD_CFLAGS_MODULE := -DMODULE
KBUILD_LDFLAGS_MODULE :=
KBUILD_LDFLAGS :=
CLANG_FLAGS :=
export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC HOSTPKG_CONFIG export CPP AR NM STRIP OBJCOPY OBJDUMP READELF PAHOLE RESOLVE_BTFIDS LEX YACC AWK INSTALLKERNEL export PERL PYTHON3 CHECK CHECKFLAGS MAKE UTS_MACHINE HOSTCXX export KGZIP KBZIP2 KLZOP LZMA LZ4 XZ ZSTD export KBUILD_HOSTCXXFLAGS KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS LDFLAGS_MODULE export KBUILD_USERCFLAGS KBUILD_USERLDFLAGS
export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS KBUILD_LDFLAGS export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL export PAHOLE_FLAGS
Files to ignore in find ... statements
export RCS_FIND_IGNORE := ( -name SCCS -o -name BitKeeper -o -name .svn -o
-name CVS -o -name .pc -o -name .hg -o -name .git )
-prune -o
export RCS_TAR_IGNORE := --exclude SCCS --exclude BitKeeper --exclude .svn
--exclude CVS --exclude .pc --exclude .hg --exclude .git
===========================================================================
Rules shared between *config targets and build targets
Basic helpers built in scripts/basic/
PHONY += scripts_basic scripts_basic: $(Q)$(MAKE) $(build)=scripts/basic
PHONY += outputmakefile ifdef building_out_of_srctree
Before starting out-of-tree build, make sure the source tree is clean.
outputmakefile generates a Makefile in the output directory, if using a
separate output directory. This allows convenient use of make in the
output directory.
At the same time when output Makefile generated, generate .gitignore to
ignore whole output directory
quiet_cmd_makefile = GEN Makefile
cmd_makefile = {
echo "# Automatically generated by $(srctree)/Makefile: don't edit";
echo "include $(srctree)/Makefile";
} > Makefile
outputmakefile:
$(Q)if [ -f $(srctree)/.config -o
-d $(srctree)/include/config -o
-d $(srctree)/arch/$(SRCARCH)/include/generated ]; then
echo >&2 "";
echo >&2 " The source tree is not clean, please run 'make$(if $(findstring command line, $(origin ARCH)), ARCH=$(ARCH)) mrproper'";
echo >&2 "*** in $(abs_srctree)";
echo >&2 "**";
false;
fi
$(Q)ln -fsn $(srctree) source
$(call cmd,makefile)
$(Q)test -e .gitignore ||
{ echo "# this is build directory, ignore it"; echo ""; } > .gitignore
endif
The expansion should be delayed until arch/$(SRCARCH)/Makefile is included.
Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile.
CC_VERSION_TEXT is referenced from Kconfig (so it needs export),
and from include/config/auto.conf.cmd to detect the compiler upgrade.
CC_VERSION_TEXT = $(subst $(pound),,$(shell LC_ALL=C $(CC) --version 2>/dev/null | head -n 1))
ifneq ($(findstring clang,$(CC_VERSION_TEXT)),) include $(srctree)/scripts/Makefile.clang endif
Include this also for config targets because some architectures need
cc-cross-prefix to determine CROSS_COMPILE.
ifdef need-compiler include $(srctree)/scripts/Makefile.compiler endif
ifdef config-build
===========================================================================
*config targets only - make sure prerequisites are updated, and descend
in scripts/kconfig to make the *config target
Read arch specific Makefile to set KBUILD_DEFCONFIG as needed.
KBUILD_DEFCONFIG may point out an alternative default configuration
used for 'make defconfig'
include $(srctree)/arch/$(SRCARCH)/Makefile export KBUILD_DEFCONFIG KBUILD_KCONFIG CC_VERSION_TEXT
config: outputmakefile scripts_basic FORCE $(Q)$(MAKE) $(build)=scripts/kconfig $@
%config: outputmakefile scripts_basic FORCE $(Q)$(MAKE) $(build)=scripts/kconfig $@
else #!config-build
===========================================================================
Build targets only - this includes vmlinux, arch specific targets, clean
targets and others. In general all targets except *config targets.
If building an external module we do not care about the all: rule
but instead __all depend on modules
PHONY += all ifeq ($(KBUILD_EXTMOD),) __all: all else __all: modules endif
Decide whether to build built-in, modular, or both.
Normally, just do built-in.
KBUILD_MODULES := KBUILD_BUILTIN := 1
If we have only "make modules", don't compile built-in objects.
ifeq ($(MAKECMDGOALS),modules) KBUILD_BUILTIN := endif
If we have "make modules", compile modules
in addition to whatever we do anyway.
Just "make" or "make all" shall build modules as well
ifneq ($(filter all modules nsdeps %compile_commands.json clang-%,$(MAKECMDGOALS)),) KBUILD_MODULES := 1 endif
ifeq ($(MAKECMDGOALS),) KBUILD_MODULES := 1 endif
export KBUILD_MODULES KBUILD_BUILTIN
ifdef need-config include include/config/auto.conf endif
ifeq ($(KBUILD_EXTMOD),)
Objects we will link into vmlinux / subdirs we need to visit
core-y := init/ usr/ arch/$(SRCARCH)/ drivers-y := drivers/ sound/ drivers-$(CONFIG_SAMPLES) += samples/ drivers-$(CONFIG_NET) += net/ drivers-y += virt/ libs-y := lib/ endif # KBUILD_EXTMOD
The all: target is the default when no target is given on the
command line.
This allow a user to issue only 'make' to build a kernel including modules
Defaults to vmlinux, but the arch makefile usually adds further targets
all: vmlinux
CFLAGS_GCOV := -fprofile-arcs -ftest-coverage ifdef CONFIG_CC_IS_GCC CFLAGS_GCOV += -fno-tree-loop-im endif export CFLAGS_GCOV
The arch Makefiles can override CC_FLAGS_FTRACE. We may also append it later.
ifdef CONFIG_FUNCTION_TRACER CC_FLAGS_FTRACE := -pg endif
include $(srctree)/arch/$(SRCARCH)/Makefile
ifdef need-config ifdef may-sync-config
Read in dependencies to all Kconfig* files, make sure to run syncconfig if
changes are detected. This should be included after arch/$(SRCARCH)/Makefile
because some architectures define CROSS_COMPILE there.
include include/config/auto.conf.cmd
$(KCONFIG_CONFIG): @echo >&2 '' @echo >&2 ' Configuration file "$@" not found!' @echo >&2 '' @echo >&2 ' Please run some configurator (e.g. "make oldconfig" or' @echo >&2 '*** "make menuconfig" or "make xconfig").' @echo >&2 '***' @/bin/false
The actual configuration files used during the build are stored in
include/generated/ and include/config/. Update them if .config is newer than
include/config/auto.conf (which mirrors .config).
This exploits the 'multi-target pattern rule' trick.
The syncconfig should be executed only once to make all the targets.
(Note: use the grouped target '&:' when we bump to GNU Make 4.3)
Do not use $(call cmd,...) here. That would suppress prompts from syncconfig,
so you cannot notice that Kconfig is waiting for the user input.
%/config/auto.conf %/config/auto.conf.cmd %/generated/autoconf.h: $(KCONFIG_CONFIG) $(Q)$(kecho) " SYNC $@" $(Q)$(MAKE) -f $(srctree)/Makefile syncconfig else # !may-sync-config
External modules and some install targets need include/generated/autoconf.h
and include/config/auto.conf but do not care if they are up-to-date.
Use auto.conf to trigger the test
PHONY += include/config/auto.conf
include/config/auto.conf:
$(Q)test -e include/generated/autoconf.h -a -e $@ || (
echo >&2;
echo >&2 " ERROR: Kernel configuration is invalid.";
echo >&2 " include/generated/autoconf.h or $@ are missing.";
echo >&2 " Run 'make oldconfig && make prepare' on kernel src to fix it.";
echo >&2 ;
/bin/false)
endif # may-sync-config endif # need-config
KBUILD_CFLAGS += -fno-delete-null-pointer-checks KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,) KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation) KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow) KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE KBUILD_CFLAGS += -O2 else ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE KBUILD_CFLAGS += -Os endif
Tell gcc to never replace conditional load with a non-conditional one
ifdef CONFIG_CC_IS_GCC
gcc-10 renamed --param=allow-store-data-races=0 to
-fno-allow-store-data-races.
KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0) KBUILD_CFLAGS += $(call cc-option,-fno-allow-store-data-races) endif
ifdef CONFIG_READABLE_ASM
Disable optimizations that make assembler listings hard to read.
reorder blocks reorders the control in the function
ipa clone creates specialized cloned functions
partial inlining inlines only parts of functions
KBUILD_CFLAGS += -fno-reorder-blocks -fno-ipa-cp-clone -fno-partial-inlining endif
ifneq ($(CONFIG_FRAME_WARN),0) KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_FRAME_WARN) endif
stackp-flags-y := -fno-stack-protector stackp-flags-$(CONFIG_STACKPROTECTOR) := -fstack-protector stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong
KBUILD_CFLAGS += $(stackp-flags-y)
KBUILD_CFLAGS-$(CONFIG_WERROR) += -Werror KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
ifdef CONFIG_CC_IS_CLANG KBUILD_CPPFLAGS += -Qunused-arguments
The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable.
KBUILD_CFLAGS += -Wno-gnu else
gcc inanely warns about local variables called 'main'
KBUILD_CFLAGS += -Wno-main endif
These warnings generated too much noise in a regular build.
Use make W=1 to enable them (see scripts/Makefile.extrawarn)
KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable) KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
These result in bogus false positives
KBUILD_CFLAGS += $(call cc-disable-warning, dangling-pointer)
ifdef CONFIG_FRAME_POINTER KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls else
Some targets (ARM with Thumb2, for example), can't be built with frame
pointers. For those, we don't have FUNCTION_TRACER automatically
select FRAME_POINTER. However, FUNCTION_TRACER adds -pg, and this is
incompatible with -fomit-frame-pointer with current GCC, so we don't use
-fomit-frame-pointer with FUNCTION_TRACER.
ifndef CONFIG_FUNCTION_TRACER KBUILD_CFLAGS += -fomit-frame-pointer endif endif
Initialize all stack variables with a 0xAA pattern.
ifdef CONFIG_INIT_STACK_ALL_PATTERN KBUILD_CFLAGS += -ftrivial-auto-var-init=pattern endif
Initialize all stack variables with a zero value.
ifdef CONFIG_INIT_STACK_ALL_ZERO KBUILD_CFLAGS += -ftrivial-auto-var-init=zero ifdef CONFIG_CC_IS_CLANG
https://bugs.llvm.org/show_bug.cgi?id=45497
KBUILD_CFLAGS += -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang endif endif
While VLAs have been removed, GCC produces unreachable stack probes
for the randomize_kstack_offset feature. Disable it for all compilers.
KBUILD_CFLAGS += $(call cc-option, -fno-stack-clash-protection)
Clear used registers at func exit (to reduce data lifetime and ROP gadgets).
ifdef CONFIG_ZERO_CALL_USED_REGS KBUILD_CFLAGS += -fzero-call-used-regs=used-gpr endif
ifdef CONFIG_FUNCTION_TRACER ifdef CONFIG_FTRACE_MCOUNT_USE_CC CC_FLAGS_FTRACE += -mrecord-mcount ifdef CONFIG_HAVE_NOP_MCOUNT ifeq ($(call cc-option-yn, -mnop-mcount),y) CC_FLAGS_FTRACE += -mnop-mcount CC_FLAGS_USING += -DCC_USING_NOP_MCOUNT endif endif endif ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL CC_FLAGS_USING += -DCC_USING_NOP_MCOUNT endif ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT ifdef CONFIG_HAVE_C_RECORDMCOUNT BUILD_C_RECORDMCOUNT := y export BUILD_C_RECORDMCOUNT endif endif ifdef CONFIG_HAVE_FENTRY
s390-linux-gnu-gcc did not support -mfentry until gcc-9.
ifeq ($(call cc-option-yn, -mfentry),y) CC_FLAGS_FTRACE += -mfentry CC_FLAGS_USING += -DCC_USING_FENTRY endif endif export CC_FLAGS_FTRACE KBUILD_CFLAGS += $(CC_FLAGS_FTRACE) $(CC_FLAGS_USING) KBUILD_AFLAGS += $(CC_FLAGS_USING) endif
We trigger additional mismatches with less inlining
ifdef CONFIG_DEBUG_SECTION_MISMATCH KBUILD_CFLAGS += -fno-inline-functions-called-once endif
ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections LDFLAGS_vmlinux += --gc-sections endif
ifdef CONFIG_SHADOW_CALL_STACK CC_FLAGS_SCS := -fsanitize=shadow-call-stack KBUILD_CFLAGS += $(CC_FLAGS_SCS) export CC_FLAGS_SCS endif
ifdef CONFIG_LTO_CLANG ifdef CONFIG_LTO_CLANG_THIN CC_FLAGS_LTO := -flto=thin -fsplit-lto-unit KBUILD_LDFLAGS += --thinlto-cache-dir=$(extmod_prefix).thinlto-cache else CC_FLAGS_LTO := -flto endif CC_FLAGS_LTO += -fvisibility=hidden
Limit inlining across translation units to reduce binary size
KBUILD_LDFLAGS += -mllvm -import-instr-limit=5
Check for frame size exceeding threshold during prolog/epilog insertion
when using lld < 13.0.0.
ifneq ($(CONFIG_FRAME_WARN),0)
ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo ?),0)
KBUILD_LDFLAGS += -plugin-opt=-warn-stack-size=$(CONFIG_FRAME_WARN)
endif
endif
endif
ifdef CONFIG_LTO KBUILD_CFLAGS += -fno-lto $(CC_FLAGS_LTO) KBUILD_AFLAGS += -fno-lto export CC_FLAGS_LTO endif
ifdef CONFIG_CFI_CLANG
CC_FLAGS_CFI := -fsanitize=cfi
-fsanitize-cfi-cross-dso
-fno-sanitize-cfi-canonical-jump-tables
-fno-sanitize-trap=cfi
-fno-sanitize-blacklist
ifdef CONFIG_CFI_PERMISSIVE CC_FLAGS_CFI += -fsanitize-recover=cfi endif
If LTO flags are filtered out, we must also filter out CFI.
CC_FLAGS_LTO += $(CC_FLAGS_CFI) KBUILD_CFLAGS += $(CC_FLAGS_CFI) export CC_FLAGS_CFI endif
ifdef CONFIG_DEBUG_FORCE_FUNCTION_ALIGN_64B KBUILD_CFLAGS += -falign-functions=64 endif
arch Makefile may override CC so keep this after arch Makefile is included
NOSTDINC_FLAGS += -nostdinc
warn about C99 declaration after statement
KBUILD_CFLAGS += -Wdeclaration-after-statement
Variable Length Arrays (VLAs) should not be used anywhere in the kernel
KBUILD_CFLAGS += -Wvla
disable pointer signed / unsigned warnings in gcc 4.0
KBUILD_CFLAGS += -Wno-pointer-sign
In order to make sure new function cast mismatches are not introduced
in the kernel (to avoid tripping CFI checking), the kernel should be
globally built with -Wcast-function-type.
KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type)
disable stringop warnings in gcc 8+
KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
We'll want to enable this eventually, but it's not going away for 5.7 at least
KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow)
Another good warning that we'll want to enable eventually
KBUILD_CFLAGS += $(call cc-disable-warning, restrict)
Enabled with W=2, disabled by default as noisy
ifdef CONFIG_CC_IS_GCC KBUILD_CFLAGS += -Wno-maybe-uninitialized endif
ifdef CONFIG_CC_IS_GCC
The allocators already balk at large sizes, so silence the compiler
warnings for bounds checks involving those possible values. While
-Wno-alloc-size-larger-than would normally be used here, earlier versions
of gcc (<9.1) weirdly don't handle the option correctly when other
warnings are produced (?!). Using -Walloc-size-larger-than=SIZE_MAX
doesn't work (as it is documented to), silently resolving to "0" prior to
version 9.1 (and producing an error more recently). Numeric values larger
than PTRDIFF_MAX also don't work prior to version 9.1, which are silently
ignored, continuing to default to PTRDIFF_MAX. So, left with no other
choice, we must perform a versioned check to disable this warning.
https://lore.kernel.org/lkml/20210824115859.187f272f@canb.auug.org.au
KBUILD_CFLAGS += $(call cc-ifversion, -ge, 0901, -Wno-alloc-size-larger-than) endif
disable invalid "can't wrap" optimizations for signed / pointers
KBUILD_CFLAGS += -fno-strict-overflow
Make sure -fstack-check isn't enabled (like gentoo apparently did)
KBUILD_CFLAGS += -fno-stack-check
conserve stack if available
ifdef CONFIG_CC_IS_GCC KBUILD_CFLAGS += -fconserve-stack endif
Prohibit date/time macros, which would make the build non-deterministic
KBUILD_CFLAGS += -Werror=date-time
enforce correct pointer usage
KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
Require designated initializers for all marked structures
KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
change FILE to the relative path from the srctree
KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
include additional Makefiles when needed
include-y := scripts/Makefile.extrawarn include-$(CONFIG_DEBUG_INFO) += scripts/Makefile.debug include-$(CONFIG_KASAN) += scripts/Makefile.kasan include-$(CONFIG_KCSAN) += scripts/Makefile.kcsan include-$(CONFIG_UBSAN) += scripts/Makefile.ubsan include-$(CONFIG_KCOV) += scripts/Makefile.kcov include-$(CONFIG_RANDSTRUCT) += scripts/Makefile.randstruct include-$(CONFIG_GCC_PLUGINS) += scripts/Makefile.gcc-plugins
include $(addprefix $(srctree)/, $(include-y))
scripts/Makefile.gcc-plugins is intentionally included last.
Do not add $(call cc-option,...) below this line. When you build the kernel
from the clean source tree, the GCC plugins do not exist at this point.
Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
KBUILD_CPPFLAGS += $(KCPPFLAGS) KBUILD_AFLAGS += $(KAFLAGS) KBUILD_CFLAGS += $(KCFLAGS)
KBUILD_LDFLAGS_MODULE += --build-id=sha1 LDFLAGS_vmlinux += --build-id=sha1
KBUILD_LDFLAGS += -z noexecstack ifeq ($(CONFIG_LD_IS_BFD),y) KBUILD_LDFLAGS += $(call ld-option,--no-warn-rwx-segments) endif
ifeq ($(CONFIG_STRIP_ASM_SYMS),y) LDFLAGS_vmlinux += $(call ld-option, -X,) endif
ifeq ($(CONFIG_RELR),y) LDFLAGS_vmlinux += --pack-dyn-relocs=relr --use-android-relr-tags endif
We never want expected sections to be placed heuristically by the
linker. All sections should be explicitly named in the linker script.
ifdef CONFIG_LD_ORPHAN_WARN LDFLAGS_vmlinux += --orphan-handling=warn endif
Align the bit size of userspace programs with the kernel
KBUILD_USERCFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CFLAGS)) KBUILD_USERLDFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CFLAGS))
make the checker run with the right architecture
CHECKFLAGS += --arch=$(ARCH)
insure the checker run with the right endianness
CHECKFLAGS += $(if $(CONFIG_CPU_BIG_ENDIAN),-mbig-endian,-mlittle-endian)
the checker needs the correct machine size
CHECKFLAGS += $(if $(CONFIG_64BIT),-m64,-m32)
Default kernel image to build when no specific target is given.
KBUILD_IMAGE may be overruled on the command line or
set in the environment
Also any assignments in arch/$(ARCH)/Makefile take precedence over
this default value
export KBUILD_IMAGE ?= vmlinux
INSTALL_PATH specifies where to place the updated kernel and system map
images. Default is /boot, but you can set it to other values
export INSTALL_PATH ?= /boot
INSTALL_DTBS_PATH specifies a prefix for relocations required by build roots.
Like INSTALL_MOD_PATH, it isn't defined in the Makefile, but can be passed as
an argument if needed. Otherwise it defaults to the kernel install path
export INSTALL_DTBS_PATH ?= $(INSTALL_PATH)/dtbs/$(KERNELRELEASE)
INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
relocations required by build roots. This is not defined in the
makefile but the argument can be passed to make if needed.
MODLIB = $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE) export MODLIB
PHONY += prepare0
export extmod_prefix = $(if $(KBUILD_EXTMOD),$(KBUILD_EXTMOD)/) export MODORDER := $(extmod_prefix)modules.order export MODULES_NSDEPS := $(extmod_prefix)modules.nsdeps
ifeq ($(KBUILD_EXTMOD),) core-y += kernel/ certs/ mm/ fs/ ipc/ security/ crypto/ core-$(CONFIG_BLOCK) += block/ core-$(CONFIG_IO_URING) += io_uring/
vmlinux-dirs := $(patsubst %/,%,$(filter %/,
$(core-y) $(core-m) $(drivers-y) $(drivers-m)
$(libs-y) $(libs-m)))
vmlinux-alldirs := $(sort $(vmlinux-dirs) Documentation
$(patsubst %/,%,$(filter %/, $(core-)
$(drivers-) $(libs-))))
build-dirs := $(vmlinux-dirs) clean-dirs := $(vmlinux-alldirs)
subdir-modorder := $(addsuffix /modules.order, $(build-dirs))
Externally visible symbols (used by link-vmlinux.sh)
KBUILD_VMLINUX_OBJS := $(head-y) $(patsubst %/,%/built-in.a, $(core-y)) KBUILD_VMLINUX_OBJS += $(addsuffix built-in.a, $(filter %/, $(libs-y))) ifdef CONFIG_MODULES KBUILD_VMLINUX_OBJS += $(patsubst %/, %/lib.a, $(filter %/, $(libs-y))) KBUILD_VMLINUX_LIBS := $(filter-out %/, $(libs-y)) else KBUILD_VMLINUX_LIBS := $(patsubst %/,%/lib.a, $(libs-y)) endif KBUILD_VMLINUX_OBJS += $(patsubst %/,%/built-in.a, $(drivers-y))
export KBUILD_VMLINUX_OBJS KBUILD_VMLINUX_LIBS export KBUILD_LDS := arch/$(SRCARCH)/kernel/vmlinux.lds
used by scripts/Makefile.package
export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) LICENSES arch include scripts tools)
vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)
Recurse until adjust_autoksyms.sh is satisfied
PHONY += autoksyms_recursive ifdef CONFIG_TRIM_UNUSED_KSYMS
For the kernel to actually contain only the needed exported symbols,
we have to build modules as well to determine what those symbols are.
(this can be evaluated only once include/config/auto.conf has been included)
KBUILD_MODULES := 1
autoksyms_recursive: descend modules.order
$(Q)$(CONFIG_SHELL) $(srctree)/scripts/adjust_autoksyms.sh
"$(MAKE) -f $(srctree)/Makefile autoksyms_recursive"
endif
autoksyms_h := $(if $(CONFIG_TRIM_UNUSED_KSYMS), include/generated/autoksyms.h)
quiet_cmd_autoksyms_h = GEN $@
cmd_autoksyms_h = mkdir -p $(dir $@);
$(CONFIG_SHELL) $(srctree)/scripts/gen_autoksyms.sh $@
$(autoksyms_h): $(call cmd,autoksyms_h)
ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
Final link of vmlinux with optional arch pass after final link
cmd_link-vmlinux =
$(CONFIG_SHELL) $< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)";
$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
vmlinux: scripts/link-vmlinux.sh autoksyms_recursive $(vmlinux-deps) FORCE +$(call if_changed_dep,link-vmlinux)
targets := vmlinux
The actual objects are generated when descending,
make sure no implicit rule kicks in
$(sort $(vmlinux-deps) $(subdir-modorder)): descend ;
filechk_kernel.release =
echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"
Store (new) KERNELRELEASE string in include/config/kernel.release
include/config/kernel.release: FORCE $(call filechk,kernel.release)
Additional helpers built in scripts/
Carefully list dependencies so we do not try to build scripts twice
in parallel
PHONY += scripts scripts: scripts_basic scripts_dtc $(Q)$(MAKE) $(build)=$(@)
Things we need to do before we recursively start building the kernel
or the modules are listed in "prepare".
A multi level approach is used. prepareN is processed before prepareN-1.
archprepare is used in arch Makefiles and when processed asm symlink,
version.h and scripts_basic is processed / created.
PHONY += prepare archprepare
archprepare: outputmakefile archheaders archscripts scripts include/config/kernel.release
asm-generic $(version_h) $(autoksyms_h) include/generated/utsrelease.h
include/generated/autoconf.h remove-stale-files
prepare0: archprepare $(Q)$(MAKE) $(build)=scripts/mod $(Q)$(MAKE) $(build)=.
All the preparing..
prepare: prepare0
PHONY += remove-stale-files remove-stale-files: $(Q)$(srctree)/scripts/remove-stale-files
Support for using generic headers in asm-generic
asm-generic := -f $(srctree)/scripts/Makefile.asm-generic obj
PHONY += asm-generic uapi-asm-generic
asm-generic: uapi-asm-generic
$(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/asm
generic=include/asm-generic
uapi-asm-generic:
$(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/uapi/asm
generic=include/uapi/asm-generic
Generate some files
---------------------------------------------------------------------------
KERNELRELEASE can change from a few different places, meaning version.h
needs to be updated, so this check is forced on all builds
uts_len := 64
define filechk_utsrelease.h
if [ echo -n "$(KERNELRELEASE)" | wc -c -gt $(uts_len) ]; then
echo '"$(KERNELRELEASE)" exceeds $(uts_len) characters' >&2;
exit 1;
fi;
echo #define UTS_RELEASE "$(KERNELRELEASE)"
endef
define filechk_version.h
if [ $(SUBLEVEL) -gt 255 ]; then
echo #define LINUX_VERSION_CODE $(shell
expr $(VERSION) * 65536 + $(PATCHLEVEL) * 256 + 255);
else
echo #define LINUX_VERSION_CODE $(shell
expr $(VERSION) * 65536 + $(PATCHLEVEL) * 256 + $(SUBLEVEL));
fi;
echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) +
((c) > 255 ? 255 : (c)))';
echo #define LINUX_VERSION_MAJOR $(VERSION);
echo #define LINUX_VERSION_PATCHLEVEL $(PATCHLEVEL);
echo #define LINUX_VERSION_SUBLEVEL $(SUBLEVEL)
endef
$(version_h): PATCHLEVEL := $(or $(PATCHLEVEL), 0) $(version_h): SUBLEVEL := $(or $(SUBLEVEL), 0) $(version_h): FORCE $(call filechk,version.h)
include/generated/utsrelease.h: include/config/kernel.release FORCE $(call filechk,utsrelease.h)
PHONY += headerdep
headerdep:
$(Q)find $(srctree)/include/ -name '*.h' | xargs --max-args 1
$(srctree)/scripts/headerdep.pl -I$(srctree)/include
---------------------------------------------------------------------------
Kernel headers
#Default location for installed headers export INSTALL_HDR_PATH = $(objtree)/usr
quiet_cmd_headers_install = INSTALL $(INSTALL_HDR_PATH)/include
cmd_headers_install =
mkdir -p $(INSTALL_HDR_PATH);
rsync -mrl --include='/' --include='.h' --exclude='*'
usr/include $(INSTALL_HDR_PATH)
PHONY += headers_install headers_install: headers $(call cmd,headers_install)
PHONY += archheaders archscripts
hdr-inst := -f $(srctree)/scripts/Makefile.headersinst obj
PHONY += headers headers: $(version_h) scripts_unifdef uapi-asm-generic archheaders archscripts $(if $(filter um, $(SRCARCH)), $(error Headers not exportable for UML)) $(Q)$(MAKE) $(hdr-inst)=include/uapi $(Q)$(MAKE) $(hdr-inst)=arch/$(SRCARCH)/include/uapi
ifdef CONFIG_HEADERS_INSTALL prepare: headers endif
PHONY += scripts_unifdef scripts_unifdef: scripts_basic $(Q)$(MAKE) $(build)=scripts scripts/unifdef
---------------------------------------------------------------------------
Install
Many distributions have the custom install script, /sbin/installkernel.
If DKMS is installed, 'make install' will eventually recurse back
to this Makefile to build and install external modules.
Cancel sub_make_done so that options such as M=, V=, etc. are parsed.
quiet_cmd_install = INSTALL $(INSTALL_PATH) cmd_install = unset sub_make_done; $(srctree)/scripts/install.sh
---------------------------------------------------------------------------
Tools
ifdef CONFIG_OBJTOOL prepare: tools/objtool endif
ifdef CONFIG_BPF ifdef CONFIG_DEBUG_INFO_BTF prepare: tools/bpf/resolve_btfids endif endif
PHONY += resolve_btfids_clean
resolve_btfids_O = $(abspath $(objtree))/tools/bpf/resolve_btfids
tools/bpf/resolve_btfids directory might not exist
in output directory, skip its clean in that case
resolve_btfids_clean: ifneq ($(wildcard $(resolve_btfids_O)),) $(Q)$(MAKE) -sC $(srctree)/tools/bpf/resolve_btfids O=$(resolve_btfids_O) clean endif
Clear a bunch of variables before executing the submake
ifeq ($(quiet),silent_) tools_silent=s endif
tools/: FORCE $(Q)mkdir -p $(objtree)/tools $(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(tools_silent) $(filter --j% -j,$(MAKEFLAGS))" O=$(abspath $(objtree)) subdir=tools -C $(srctree)/tools/
tools/%: FORCE $(Q)mkdir -p $(objtree)/tools $(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(tools_silent) $(filter --j% -j,$(MAKEFLAGS))" O=$(abspath $(objtree)) subdir=tools -C $(srctree)/tools/ $*
---------------------------------------------------------------------------
Kernel selftest
PHONY += kselftest kselftest: headers $(Q)$(MAKE) -C $(srctree)/tools/testing/selftests run_tests
kselftest-%: headers FORCE $(Q)$(MAKE) -C $(srctree)/tools/testing/selftests $*
PHONY += kselftest-merge
kselftest-merge:
$(if $(wildcard $(objtree)/.config),, $(error No .config exists, config your kernel first!))
$(Q)find $(srctree)/tools/testing/selftests -name config |
xargs $(srctree)/scripts/kconfig/merge_config.sh -m $(objtree)/.config
$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
---------------------------------------------------------------------------
Devicetree files
ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/boot/dts/),) dtstree := arch/$(SRCARCH)/boot/dts endif
ifneq ($(dtstree),)
%.dtb: dtbs_prepare $(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
%.dtbo: dtbs_prepare $(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
PHONY += dtbs dtbs_prepare dtbs_install dtbs_check dtbs: dtbs_prepare $(Q)$(MAKE) $(build)=$(dtstree)
include/config/kernel.release is actually needed when installing DTBs because
INSTALL_DTBS_PATH contains $(KERNELRELEASE). However, we do not want to make
dtbs_install depend on it as dtbs_install may run as root.
dtbs_prepare: include/config/kernel.release scripts_dtc
ifneq ($(filter dtbs_check, $(MAKECMDGOALS)),) export CHECK_DTBS=y dtbs: dt_binding_check endif
dtbs_check: dtbs
dtbs_install: $(Q)$(MAKE) $(dtbinst)=$(dtstree) dst=$(INSTALL_DTBS_PATH)
ifdef CONFIG_OF_EARLY_FLATTREE all: dtbs endif
endif
PHONY += scripts_dtc scripts_dtc: scripts_basic $(Q)$(MAKE) $(build)=scripts/dtc
ifneq ($(filter dt_binding_check, $(MAKECMDGOALS)),) export CHECK_DT_BINDING=y endif
PHONY += dt_binding_check dt_binding_check: scripts_dtc $(Q)$(MAKE) $(build)=Documentation/devicetree/bindings
---------------------------------------------------------------------------
Modules
ifdef CONFIG_MODULES
By default, build modules as well
all: modules
When we're building modules with modversions, we need to consider
the built-in objects during the descend as well, in order to
make sure the checksums are up to date before we record them.
ifdef CONFIG_MODVERSIONS KBUILD_BUILTIN := 1 endif
Build modules
A module can be listed more than once in obj-m resulting in
duplicate lines in modules.order files. Those are removed
using awk while concatenating to the final file.
PHONY += modules modules: $(if $(KBUILD_BUILTIN),vmlinux) modules_check modules_prepare
cmd_modules_order = $(AWK) '!x[$$0]++' $(real-prereqs) > $@
modules.order: $(subdir-modorder) FORCE $(call if_changed,modules_order)
targets += modules.order
Target to prepare building external modules
PHONY += modules_prepare modules_prepare: prepare $(Q)$(MAKE) $(build)=scripts scripts/module.lds
export modules_sign_only :=
ifeq ($(CONFIG_MODULE_SIG),y) PHONY += modules_sign modules_sign: modules_install @:
modules_sign is a subset of modules_install.
'make modules_install modules_sign' is equivalent to 'make modules_install'.
ifeq ($(filter modules_install,$(MAKECMDGOALS)),) modules_sign_only := y endif endif
modinst_pre := ifneq ($(filter modules_install,$(MAKECMDGOALS)),) modinst_pre := __modinst_pre endif
modules_install: $(modinst_pre)
PHONY += __modinst_pre
__modinst_pre:
@rm -rf $(MODLIB)/kernel
@rm -f $(MODLIB)/source
@mkdir -p $(MODLIB)/kernel
@ln -s $(abspath $(srctree)) $(MODLIB)/source
@if [ ! $(objtree) -ef $(MODLIB)/build ]; then
rm -f $(MODLIB)/build ;
ln -s $(CURDIR) $(MODLIB)/build ;
fi
@sed 's:^:kernel/:' modules.order > $(MODLIB)/modules.order
@cp -f modules.builtin $(MODLIB)/
@cp -f $(objtree)/modules.builtin.modinfo $(MODLIB)/
endif # CONFIG_MODULES
Cleaning is done on three levels.
make clean Delete most generated files
Leave enough to build external modules
make mrproper Delete the current configuration, and all generated files
make distclean Remove editor backup files, patch leftover files and the like
Directories & files removed with 'make clean'
CLEAN_FILES += include/ksym vmlinux.symvers modules-only.symvers
modules.builtin modules.builtin.modinfo modules.nsdeps
compile_commands.json .thinlto-cache
Directories & files removed with 'make mrproper'
MRPROPER_FILES += include/config include/generated
arch/$(SRCARCH)/include/generated .objdiff
debian snap tar-install
.config .config.old .version
Module.symvers
certs/signing_key.pem
certs/x509.genkey
vmlinux-gdb.py
*.spec
clean - Delete most, but leave enough to build external modules
clean: rm-files := $(CLEAN_FILES)
PHONY += archclean vmlinuxclean
vmlinuxclean: $(Q)$(CONFIG_SHELL) $(srctree)/scripts/link-vmlinux.sh clean $(Q)$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) clean)
clean: archclean vmlinuxclean resolve_btfids_clean
mrproper - Delete all generated files, including .config
mrproper: rm-files := $(wildcard $(MRPROPER_FILES)) mrproper-dirs := $(addprefix mrproper,scripts)
PHONY += $(mrproper-dirs) mrproper $(mrproper-dirs): $(Q)$(MAKE) $(clean)=$(patsubst mrproper%,%,$@)
mrproper: clean $(mrproper-dirs) $(call cmd,rmfiles)
distclean
PHONY += distclean
distclean: mrproper
@find . $(RCS_FIND_IGNORE)
( -name '.orig' -o -name '.rej' -o -name '~'
-o -name '.bak' -o -name '##' -o -name '%'
-o -name 'core' -o -name tags -o -name TAGS -o -name 'cscope*'
-o -name GPATH -o -name GRTAGS -o -name GSYMS -o -name GTAGS )
-type f -print | xargs rm -f
Packaging of the kernel to various formats
---------------------------------------------------------------------------
%src-pkg: FORCE $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.package $@ %pkg: include/config/kernel.release FORCE $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.package $@
Brief documentation of the typical targets used
---------------------------------------------------------------------------
boards := $(wildcard $(srctree)/arch/$(SRCARCH)/configs/_defconfig) boards := $(sort $(notdir $(boards))) board-dirs := $(dir $(wildcard $(srctree)/arch/$(SRCARCH)/configs//*_defconfig)) board-dirs := $(sort $(notdir $(board-dirs:/=)))
PHONY += help
help:
@echo 'Cleaning targets:'
@echo ' clean - Remove most generated files but keep the config and'
@echo ' enough build support to build external modules'
@echo ' mrproper - Remove all generated files + config + various backup files'
@echo ' distclean - mrproper + remove editor backup and patch files'
@echo ''
@echo 'Configuration targets:'
@$(MAKE) -f $(srctree)/scripts/kconfig/Makefile help
@echo ''
@echo 'Other generic targets:'
@echo ' all - Build all targets marked with []'
@echo ' vmlinux - Build the bare kernel'
@echo '* modules - Build all modules'
@echo ' modules_install - Install all modules to INSTALL_MOD_PATH (default: /)'
@echo ' dir/ - Build all files in dir and below'
@echo ' dir/file.[ois] - Build specified target only'
@echo ' dir/file.ll - Build the LLVM assembly file'
@echo ' (requires compiler support for LLVM assembly generation)'
@echo ' dir/file.lst - Build specified mixed source/assembly target only'
@echo ' (requires a recent binutils and recent build (System.map))'
@echo ' dir/file.ko - Build module including final link'
@echo ' modules_prepare - Set up for building external modules'
@echo ' tags/TAGS - Generate tags file for editors'
@echo ' cscope - Generate cscope index'
@echo ' gtags - Generate GNU GLOBAL index'
@echo ' kernelrelease - Output the release version string (use with make -s)'
@echo ' kernelversion - Output the version stored in Makefile (use with make -s)'
@echo ' image_name - Output the image name (use with make -s)'
@echo ' headers_install - Install sanitised kernel headers to INSTALL_HDR_PATH';
echo ' (default: $(INSTALL_HDR_PATH))';
echo ''
@echo 'Static analysers:'
@echo ' checkstack - Generate a list of stack hogs'
@echo ' versioncheck - Sanity check on version.h usage'
@echo ' includecheck - Check for duplicate included header files'
@echo ' export_report - List the usages of all exported symbols'
@echo ' headerdep - Detect inclusion cycles in headers'
@echo ' coccicheck - Check with Coccinelle'
@echo ' clang-analyzer - Check with clang static analyzer'
@echo ' clang-tidy - Check with clang-tidy'
@echo ''
@echo 'Tools:'
@echo ' nsdeps - Generate missing symbol namespace dependencies'
@echo ''
@echo 'Kernel selftest:'
@echo ' kselftest - Build and run kernel selftest'
@echo ' Build, install, and boot kernel before'
@echo ' running kselftest on it'
@echo ' Run as root for full coverage'
@echo ' kselftest-all - Build kernel selftest'
@echo ' kselftest-install - Build and install kernel selftest'
@echo ' kselftest-clean - Remove all generated kselftest files'
@echo ' kselftest-merge - Merge all the config dependencies of'
@echo ' kselftest to existing .config.'
@echo ''
@$(if $(dtstree),
echo 'Devicetree:';
echo '* dtbs - Build device tree blobs for enabled boards';
echo ' dtbs_install - Install dtbs to $(INSTALL_DTBS_PATH)';
echo ' dt_binding_check - Validate device tree binding documents';
echo ' dtbs_check - Validate device tree source files';
echo '')
@echo 'Userspace tools targets:'
@echo ' use "make tools/help"'
@echo ' or "cd tools; make help"'
@echo ''
@echo 'Kernel packaging:'
@$(MAKE) -f $(srctree)/scripts/Makefile.package help
@echo ''
@echo 'Documentation targets:'
@$(MAKE) -f $(srctree)/Documentation/Makefile dochelp
@echo ''
@echo 'Architecture specific targets ($(SRCARCH)):'
@$(or $(archhelp),\
echo ' No architecture specific help defined for $(SRCARCH)')
@echo ''
@$(if $(boards), \
$(foreach b, $(boards), \
printf " %-27s - Build for %s\\n" $(b) $(subst _defconfig,,$(b));) \
echo '')
@$(if $(board-dirs), \
$(foreach b, $(board-dirs), \
printf " %-16s - Show %s-specific targets\\n" help-$(b) $(b);) \
printf " %-16s - Show all of the above\\n" help-boards; \
echo '')
@echo ' make V=0|1 [targets] 0 => quiet build (default), 1 => verbose build'
@echo ' make V=2 [targets] 2 => give reason for rebuild of target'
@echo ' make O=dir [targets] Locate all output files in "dir", including .config'
@echo ' make C=1 [targets] Check re-compiled c source with $$CHECK'
@echo ' (sparse by default)'
@echo ' make C=2 [targets] Force check of all c source with $$CHECK'
@echo ' make RECORDMCOUNT_WARN=1 [targets] Warn about ignored mcount sections'
@echo ' make W=n [targets] Enable extra build checks, n=1,2,3 where'
@echo ' 1: warnings which may be relevant and do not occur too often'
@echo ' 2: warnings which occur quite often but may still be relevant'
@echo ' 3: more obscure warnings, can most likely be ignored'
@echo ' e: warnings are being treated as errors'
@echo ' Multiple levels can be combined with W=12 or W=123'
@echo ''
@echo 'Execute "make" or "make all" to build all targets marked with [*] '
@echo 'For further info see the ./README file'
help-board-dirs := $(addprefix help-,$(board-dirs))
help-boards: $(help-board-dirs)
boards-per-dir = $(sort $(notdir $(wildcard $(srctree)/arch/$(SRCARCH)/configs/$/_defconfig)))
$(help-board-dirs): help-%:
@echo 'Architecture specific targets ($(SRCARCH) $):'
@$(if $(boards-per-dir),
$(foreach b, $(boards-per-dir),
printf " %-24s - Build for %s\n" $/$(b) $(subst _defconfig,,$(b));)
echo '')
Documentation targets
---------------------------------------------------------------------------
DOC_TARGETS := xmldocs latexdocs pdfdocs htmldocs epubdocs cleandocs
linkcheckdocs dochelp refcheckdocs
PHONY += $(DOC_TARGETS)
$(DOC_TARGETS):
$(Q)$(MAKE) $(build)=Documentation $@
Misc
---------------------------------------------------------------------------
PHONY += scripts_gdb scripts_gdb: prepare0 $(Q)$(MAKE) $(build)=scripts/gdb $(Q)ln -fsn $(abspath $(srctree)/scripts/gdb/vmlinux-gdb.py)
ifdef CONFIG_GDB_SCRIPTS all: scripts_gdb endif
else # KBUILD_EXTMOD
External module support.
When building external modules the kernel used as basis is considered
read-only, and no consistency checks are made and the make
system is not used on the basis kernel. If updates are required
in the basis kernel ordinary make commands (without M=...) must be used.
We are always building only modules.
KBUILD_BUILTIN := KBUILD_MODULES := 1
build-dirs := $(KBUILD_EXTMOD) $(MODORDER): descend @:
compile_commands.json: $(extmod_prefix)compile_commands.json PHONY += compile_commands.json
clean-dirs := $(KBUILD_EXTMOD)
clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers $(KBUILD_EXTMOD)/modules.nsdeps
$(KBUILD_EXTMOD)/compile_commands.json $(KBUILD_EXTMOD)/.thinlto-cache
PHONY += prepare
now expand this into a simple variable to reduce the cost of shell evaluations
prepare: CC_VERSION_TEXT := $(CC_VERSION_TEXT)
prepare:
@if [ "$(CC_VERSION_TEXT)" != "$(CONFIG_CC_VERSION_TEXT)" ]; then
echo >&2 "warning: the compiler differs from the one used to build the kernel";
echo >&2 " The kernel was built by: $(CONFIG_CC_VERSION_TEXT)";
echo >&2 " You are using: $(CC_VERSION_TEXT)";
fi
PHONY += help help: @echo ' Building external modules.' @echo ' Syntax: make -C path/to/kernel/src M=$$PWD target' @echo '' @echo ' modules - default target, build the module(s)' @echo ' modules_install - install the module' @echo ' clean - remove generated files in module directory only' @echo ''
no-op for external module builds
PHONY += modules_prepare
endif # KBUILD_EXTMOD
---------------------------------------------------------------------------
Modules
PHONY += modules modules_install
ifdef CONFIG_MODULES
modules: modules_check $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
PHONY += modules_check modules_check: $(MODORDER) $(Q)$(CONFIG_SHELL) $(srctree)/scripts/modules-check.sh $<
quiet_cmd_depmod = DEPMOD $(MODLIB)
cmd_depmod = $(CONFIG_SHELL) $(srctree)/scripts/depmod.sh $(DEPMOD)
$(KERNELRELEASE)
modules_install: $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst $(call cmd,depmod)
else # CONFIG_MODULES
Modules not configured
---------------------------------------------------------------------------
modules modules_install: @echo >&2 '' @echo >&2 ' The present kernel configuration has modules disabled.' @echo >&2 '*** To use the module feature, please run "make menuconfig" etc.' @echo >&2 '*** to enable CONFIG_MODULES.' @echo >&2 '***' @exit 1
endif # CONFIG_MODULES
Single targets
---------------------------------------------------------------------------
To build individual files in subdirectories, you can do like this:
make foo/bar/baz.s
The supported suffixes for single-target are listed in 'single-targets'
To build only under specific subdirectories, you can do like this:
make foo/bar/baz/
ifdef single-build
.ko is special because modpost is needed
single-ko := $(sort $(filter %.ko, $(MAKECMDGOALS)))
single-no-ko := $(filter-out $(single-ko), $(MAKECMDGOALS))
$(foreach x, o mod, $(patsubst %.ko, %.$x, $(single-ko)))
$(single-ko): single_modpost @: $(single-no-ko): descend @:
ifeq ($(KBUILD_EXTMOD),)
For the single build of in-tree modules, use a temporary file to avoid
the situation of modules_install installing an invalid modules.order.
MODORDER := .modules.tmp endif
PHONY += single_modpost single_modpost: $(single-no-ko) modules_prepare $(Q){ $(foreach m, $(single-ko), echo $(extmod_prefix)$m;) } > $(MODORDER) $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
KBUILD_MODULES := 1
export KBUILD_SINGLE_TARGETS := $(addprefix $(extmod_prefix), $(single-no-ko))
trim unrelated directories
build-dirs := $(foreach d, $(build-dirs),
$(if $(filter $(d)/%, $(KBUILD_SINGLE_TARGETS)), $(d)))
endif
ifndef CONFIG_MODULES KBUILD_MODULES := endif
Handle descending into subdirectories listed in $(build-dirs)
Preset locale variables to speed up the build process. Limit locale
tweaks to this spot to avoid wrong language settings when running
make menuconfig etc.
Error messages still appears in the original language
PHONY += descend $(build-dirs)
descend: $(build-dirs)
$(build-dirs): prepare
$(Q)$(MAKE) $(build)=$@
single-build=$(if $(filter-out $@/, $(filter $@/%, $(KBUILD_SINGLE_TARGETS))),1)
need-builtin=1 need-modorder=1
clean-dirs := $(addprefix clean, $(clean-dirs)) PHONY += $(clean-dirs) clean $(clean-dirs): $(Q)$(MAKE) $(clean)=$(patsubst clean%,%,$@)
clean: $(clean-dirs)
$(call cmd,rmfiles)
@find $(or $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE)
( -name '.[aios]' -o -name '.ko' -o -name '..cmd'
-o -name '.ko.'
-o -name '.dtb' -o -name '.dtbo' -o -name '.dtb.S' -o -name '.dt.yaml'
-o -name '.dwo' -o -name '.lst'
-o -name '.su' -o -name '.mod' -o -name '.usyms'
-o -name '..d' -o -name '..tmp' -o -name '.mod.c'
-o -name '.lex.c' -o -name '.tab.[ch]'
-o -name '.asn1.[ch]'
-o -name '.symtypes' -o -name 'modules.order'
-o -name '.tmp_'
-o -name '.c.[012].'
-o -name '.ll'
-o -name '.gcno'
-o -name '.*.symversions' ) -type f -print | xargs rm -f
Generate tags for editors
---------------------------------------------------------------------------
quiet_cmd_tags = GEN $@ cmd_tags = $(BASH) $(srctree)/scripts/tags.sh $@
tags TAGS cscope gtags: FORCE $(call cmd,tags)
Script to generate missing namespace dependencies
---------------------------------------------------------------------------
PHONY += nsdeps nsdeps: export KBUILD_NSDEPS=1 nsdeps: modules $(Q)$(CONFIG_SHELL) $(srctree)/scripts/nsdeps
Clang Tooling
---------------------------------------------------------------------------
quiet_cmd_gen_compile_commands = GEN $@ cmd_gen_compile_commands = $(PYTHON3) $< -a $(AR) -o $@ $(filter-out $<, $(real-prereqs))
$(extmod_prefix)compile_commands.json: scripts/clang-tools/gen_compile_commands.py
$(if $(KBUILD_EXTMOD),,$(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS))
$(if $(CONFIG_MODULES), $(MODORDER)) FORCE
$(call if_changed,gen_compile_commands)
targets += $(extmod_prefix)compile_commands.json
PHONY += clang-tidy clang-analyzer
ifdef CONFIG_CC_IS_CLANG quiet_cmd_clang_tools = CHECK $< cmd_clang_tools = $(PYTHON3) $(srctree)/scripts/clang-tools/run-clang-tools.py $@ $<
clang-tidy clang-analyzer: $(extmod_prefix)compile_commands.json $(call cmd,clang_tools) else clang-tidy clang-analyzer: @echo "$@ requires CC=clang" >&2 @false endif
Scripts to check various things for consistency
---------------------------------------------------------------------------
PHONY += includecheck versioncheck coccicheck export_report
includecheck:
find $(srctree)/* $(RCS_FIND_IGNORE)
-name '*.[hcS]' -type f -print | sort
| xargs $(PERL) -w $(srctree)/scripts/checkincludes.pl
versioncheck:
find $(srctree)/* $(RCS_FIND_IGNORE)
-name '*.[hcS]' -type f -print | sort
| xargs $(PERL) -w $(srctree)/scripts/checkversion.pl
coccicheck: $(Q)$(BASH) $(srctree)/scripts/$@
export_report: $(PERL) $(srctree)/scripts/export_report.pl
PHONY += checkstack kernelrelease kernelversion image_name
UML needs a little special treatment here. It wants to use the host
toolchain, so needs $(SUBARCH) passed to checkstack.pl. Everyone
else wants $(ARCH), including people doing cross-builds, which means
that $(SUBARCH) doesn't work here.
ifeq ($(ARCH), um)
CHECKSTACK_ARCH := $(SUBARCH)
else
CHECKSTACK_ARCH := $(ARCH)
endif
checkstack:
$(OBJDUMP) -d vmlinux $$(find . -name '*.ko') |
$(PERL) $(srctree)/scripts/checkstack.pl $(CHECKSTACK_ARCH)
kernelrelease: @echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"
kernelversion: @echo $(KERNELVERSION)
image_name: @echo $(KBUILD_IMAGE)
quiet_cmd_rmfiles = $(if $(wildcard $(rm-files)),CLEAN $(wildcard $(rm-files))) cmd_rmfiles = rm -rf $(rm-files)
read saved command lines for existing targets
existing-targets := $(wildcard $(sort $(targets)))
-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
endif # config-build endif # mixed-build endif # need-sub-make
PHONY += FORCE FORCE:
Declare the contents of the PHONY variable as phony. We keep that
information in a variable so we can use it in if_changed and friends.
.PHONY: $(PHONY)