xref: /openbmc/linux/Makefile (revision 2441e78b19192cd9ea1ce93027a5732a2117f026)

VERSION = 4
PATCHLEVEL = 6
SUBLEVEL = 0
EXTRAVERSION = -rc1
NAME = Blurry Fish Butt

# *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.

# o Do not use make's built-in rules and variables
#   (this increases performance and avoids hard-to-debug behaviour);
# o Look for make include files relative to root of kernel src
MAKEFLAGS += -rR --include-dir=$(CURDIR)

# 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

# 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.o 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.

# 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.
#
# 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 ($(filter 4.%,$(MAKE_VERSION)),)	# make-4
ifneq ($(filter %s ,$(firstword x$(MAKEFLAGS))),)
  quiet=silent_
endif
else					# make-3.8x
ifneq ($(filter s% -s%,$(MAKEFLAGS)),)
  quiet=silent_
endif
endif

export quiet Q KBUILD_VERBOSE

# kbuild supports saving output files in a separate directory.
# To locate output files in a separate directory two syntaxes are supported.
# In both cases the working directory must be the root of the kernel src.
# 1) O=
# Use "make O=dir/to/store/output/files/"
#
# 2) Set KBUILD_OUTPUT
# Set the environment variable KBUILD_OUTPUT to point to the directory
# where the output files shall be placed.
# export KBUILD_OUTPUT=dir/to/store/output/files/
# make
#
# The O= assignment takes precedence over the KBUILD_OUTPUT environment
# variable.

# KBUILD_SRC is set on invocation of make in OBJ directory
# KBUILD_SRC is not intended to be used by the regular user (for now)
ifeq ($(KBUILD_SRC),)

# OK, Make called in directory where kernel src resides
# Do we want to locate output files in a separate directory?
ifeq ("$(origin O)", "command line")
  KBUILD_OUTPUT := $(O)
endif

# That's our default target when none is given on the command line
PHONY := _all
_all:

# Cancel implicit rules on top Makefile
$(CURDIR)/Makefile Makefile: ;

ifneq ($(KBUILD_OUTPUT),)
# Invoke a second make in the output directory, passing relevant variables
# check that the output directory actually exists
saved-output := $(KBUILD_OUTPUT)
KBUILD_OUTPUT := $(shell mkdir -p $(KBUILD_OUTPUT) && cd $(KBUILD_OUTPUT) \
								&& /bin/pwd)
$(if $(KBUILD_OUTPUT),, \
     $(error failed to create output directory "$(saved-output)"))

PHONY += $(MAKECMDGOALS) sub-make

$(filter-out _all sub-make $(CURDIR)/Makefile, $(MAKECMDGOALS)) _all: sub-make
	@:

sub-make:
	$(Q)$(MAKE) -C $(KBUILD_OUTPUT) KBUILD_SRC=$(CURDIR) \
	-f $(CURDIR)/Makefile $(filter-out _all sub-make,$(MAKECMDGOALS))

# Leave processing to above invocation of make
skip-makefile := 1
endif # ifneq ($(KBUILD_OUTPUT),)
endif # ifeq ($(KBUILD_SRC),)

# We process the rest of the Makefile if this is the final invocation of make
ifeq ($(skip-makefile),)

# 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

# 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/sparse.txt" 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

# Use make M=dir to specify directory of external module to build
# Old syntax make ... SUBDIRS=$PWD is still supported
# Setting the environment variable KBUILD_EXTMOD take precedence
ifdef SUBDIRS
  KBUILD_EXTMOD ?= $(SUBDIRS)
endif

ifeq ("$(origin M)", "command line")
  KBUILD_EXTMOD := $(M)
endif

# 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

ifeq ($(KBUILD_SRC),)
        # building in the source tree
        srctree := .
else
        ifeq ($(KBUILD_SRC)/,$(dir $(CURDIR)))
                # building in a subdirectory of the source tree
                srctree := ..
        else
                srctree := $(KBUILD_SRC)
        endif
endif
objtree		:= .
src		:= $(srctree)
obj		:= $(objtree)

VPATH		:= $(srctree)$(if $(KBUILD_EXTMOD),:$(KBUILD_EXTMOD))

export srctree objtree VPATH

# SUBARCH tells the usermode build what the underlying arch is.  That is set
# first, and if a usermode build is happening, the "ARCH=um" on the command
# line overrides the setting of ARCH below.  If a native build is happening,
# then ARCH is assigned, getting whatever value it gets normally, and
# SUBARCH is subsequently ignored.

SUBARCH := $(shell uname -m | sed -e s/i.86/x86/ -e s/x86_64/x86/ \
				  -e s/sun4u/sparc64/ \
				  -e s/arm.*/arm/ -e s/sa110/arm/ \
				  -e s/s390x/s390/ -e s/parisc64/parisc/ \
				  -e s/ppc.*/powerpc/ -e s/mips.*/mips/ \
				  -e s/sh[234].*/sh/ -e s/aarch64.*/arm64/ )

# 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.
# A third alternative is to store a setting in .config so that plain
# "make" in the configured kernel build directory always uses that.
# Default value for CROSS_COMPILE is not to prefix executables
# Note: Some architectures assign CROSS_COMPILE in their arch/*/Makefile
ARCH		?= $(SUBARCH)
CROSS_COMPILE	?= $(CONFIG_CROSS_COMPILE:"%"=%)

# 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 sh
ifeq ($(ARCH),sh64)
       SRCARCH := sh
endif

# Additional ARCH settings for tile
ifeq ($(ARCH),tilepro)
       SRCARCH := tile
endif
ifeq ($(ARCH),tilegx)
       SRCARCH := tile
endif

# Where to locate arch specific headers
hdr-arch  := $(SRCARCH)

KCONFIG_CONFIG	?= .config
export KCONFIG_CONFIG

# SHELL used by kbuild
CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
	  else if [ -x /bin/bash ]; then echo /bin/bash; \
	  else echo sh; fi ; fi)

HOSTCC       = gcc
HOSTCXX      = g++
HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89
HOSTCXXFLAGS = -O2

ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1)
HOSTCFLAGS  += -Wno-unused-value -Wno-unused-parameter \
		-Wno-missing-field-initializers -fno-delete-null-pointer-checks
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.
# 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.

ifeq ($(MAKECMDGOALS),modules)
  KBUILD_BUILTIN := $(if $(CONFIG_MODVERSIONS),1)
endif

# If we have "make <whatever> modules", compile modules
# in addition to whatever we do anyway.
# Just "make" or "make all" shall build modules as well

ifneq ($(filter all _all modules,$(MAKECMDGOALS)),)
  KBUILD_MODULES := 1
endif

ifeq ($(MAKECMDGOALS),)
  KBUILD_MODULES := 1
endif

export KBUILD_MODULES KBUILD_BUILTIN
export KBUILD_CHECKSRC KBUILD_SRC KBUILD_EXTMOD

# We need some generic definitions (do not try to remake the file).
scripts/Kbuild.include: ;
include scripts/Kbuild.include

# Make variables (CC, etc...)
AS		= $(CROSS_COMPILE)as
LD		= $(CROSS_COMPILE)ld
CC		= $(CROSS_COMPILE)gcc
CPP		= $(CC) -E
AR		= $(CROSS_COMPILE)ar
NM		= $(CROSS_COMPILE)nm
STRIP		= $(CROSS_COMPILE)strip
OBJCOPY		= $(CROSS_COMPILE)objcopy
OBJDUMP		= $(CROSS_COMPILE)objdump
AWK		= awk
GENKSYMS	= scripts/genksyms/genksyms
INSTALLKERNEL  := installkernel
DEPMOD		= /sbin/depmod
PERL		= perl
PYTHON		= python
CHECK		= sparse

CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
		  -Wbitwise -Wno-return-void $(CF)
CFLAGS_MODULE   =
AFLAGS_MODULE   =
LDFLAGS_MODULE  =
CFLAGS_KERNEL	=
AFLAGS_KERNEL	=
CFLAGS_GCOV	= -fprofile-arcs -ftest-coverage
CFLAGS_KCOV	= -fsanitize-coverage=trace-pc


# Use USERINCLUDE when you must reference the UAPI directories only.
USERINCLUDE    := \
		-I$(srctree)/arch/$(hdr-arch)/include/uapi \
		-Iarch/$(hdr-arch)/include/generated/uapi \
		-I$(srctree)/include/uapi \
		-Iinclude/generated/uapi \
                -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$(srctree)/arch/$(hdr-arch)/include \
		-Iarch/$(hdr-arch)/include/generated/uapi \
		-Iarch/$(hdr-arch)/include/generated \
		$(if $(KBUILD_SRC), -I$(srctree)/include) \
		-Iinclude \
		$(USERINCLUDE)

KBUILD_CPPFLAGS := -D__KERNEL__

KBUILD_CFLAGS   := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
		   -fno-strict-aliasing -fno-common \
		   -Werror-implicit-function-declaration \
		   -Wno-format-security \
		   -std=gnu89

KBUILD_AFLAGS_KERNEL :=
KBUILD_CFLAGS_KERNEL :=
KBUILD_AFLAGS   := -D__ASSEMBLY__
KBUILD_AFLAGS_MODULE  := -DMODULE
KBUILD_CFLAGS_MODULE  := -DMODULE
KBUILD_LDFLAGS_MODULE := -T $(srctree)/scripts/module-common.lds

# 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
export ARCH SRCARCH CONFIG_SHELL HOSTCC HOSTCFLAGS CROSS_COMPILE AS LD CC
export CPP AR NM STRIP OBJCOPY OBJDUMP
export MAKE AWK GENKSYMS INSTALLKERNEL PERL PYTHON UTS_MACHINE
export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS

export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS
export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV CFLAGS_KCOV CFLAGS_KASAN CFLAGS_UBSAN
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 KBUILD_ARFLAGS

# When compiling out-of-tree modules, put MODVERDIR in the module
# tree rather than in the kernel tree. The kernel tree might
# even be read-only.
export MODVERDIR := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/).tmp_versions

# 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/
PHONY += scripts_basic
scripts_basic:
	$(Q)$(MAKE) $(build)=scripts/basic
	$(Q)rm -f .tmp_quiet_recordmcount

# To avoid any implicit rule to kick in, define an empty command.
scripts/basic/%: scripts_basic ;

PHONY += outputmakefile
# outputmakefile generates a Makefile in the output directory, if using a
# separate output directory. This allows convenient use of make in the
# output directory.
outputmakefile:
ifneq ($(KBUILD_SRC),)
	$(Q)ln -fsn $(srctree) source
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile \
	    $(srctree) $(objtree) $(VERSION) $(PATCHLEVEL)
endif

# Support for using generic headers in asm-generic
PHONY += asm-generic
asm-generic:
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.asm-generic \
	            src=asm obj=arch/$(SRCARCH)/include/generated/asm
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.asm-generic \
	            src=uapi/asm obj=arch/$(SRCARCH)/include/generated/uapi/asm

# 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
old_version_h := include/linux/version.h

no-dot-config-targets := clean mrproper distclean \
			 cscope gtags TAGS tags help% %docs check% coccicheck \
			 $(version_h) headers_% archheaders archscripts \
			 kernelversion %src-pkg

config-targets := 0
mixed-targets  := 0
dot-config     := 1

ifneq ($(filter $(no-dot-config-targets), $(MAKECMDGOALS)),)
	ifeq ($(filter-out $(no-dot-config-targets), $(MAKECMDGOALS)),)
		dot-config := 0
	endif
endif

ifeq ($(KBUILD_EXTMOD),)
        ifneq ($(filter config %config,$(MAKECMDGOALS)),)
                config-targets := 1
                ifneq ($(words $(MAKECMDGOALS)),1)
                        mixed-targets := 1
                endif
        endif
endif
# install and module_install need also be processed one by one
ifneq ($(filter install,$(MAKECMDGOALS)),)
        ifneq ($(filter modules_install,$(MAKECMDGOALS)),)
	        mixed-targets := 1
        endif
endif

ifeq ($(mixed-targets),1)
# ===========================================================================
# We're called with mixed targets (*config and build targets).
# Handle them one by one.

PHONY += $(MAKECMDGOALS) __build_one_by_one

$(filter-out __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
ifeq ($(config-targets),1)
# ===========================================================================
# *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 arch/$(SRCARCH)/Makefile
export KBUILD_DEFCONFIG KBUILD_KCONFIG

config: scripts_basic outputmakefile FORCE
	$(Q)$(MAKE) $(build)=scripts/kconfig $@

%config: scripts_basic outputmakefile FORCE
	$(Q)$(MAKE) $(build)=scripts/kconfig $@

else
# ===========================================================================
# Build targets only - this includes vmlinux, arch specific targets, clean
# targets and others. In general all targets except *config targets.

ifeq ($(KBUILD_EXTMOD),)
# Additional helpers built in scripts/
# Carefully list dependencies so we do not try to build scripts twice
# in parallel
PHONY += scripts
scripts: scripts_basic include/config/auto.conf include/config/tristate.conf \
	 asm-generic
	$(Q)$(MAKE) $(build)=$(@)

# Objects we will link into vmlinux / subdirs we need to visit
init-y		:= init/
drivers-y	:= drivers/ sound/ firmware/
net-y		:= net/
libs-y		:= lib/
core-y		:= usr/
virt-y		:= virt/
endif # KBUILD_EXTMOD

ifeq ($(dot-config),1)
# Read in config
-include include/config/auto.conf

ifeq ($(KBUILD_EXTMOD),)
# Read in dependencies to all Kconfig* files, make sure to run
# oldconfig if changes are detected.
-include include/config/auto.conf.cmd

# To avoid any implicit rule to kick in, define an empty command
$(KCONFIG_CONFIG) include/config/auto.conf.cmd: ;

# If .config is newer than include/config/auto.conf, someone tinkered
# with it and forgot to run make oldconfig.
# if auto.conf.cmd is missing then we are probably in a cleaned tree so
# we execute the config step to be sure to catch updated Kconfig files
include/config/%.conf: $(KCONFIG_CONFIG) include/config/auto.conf.cmd
	$(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
else
# external modules needs 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 # KBUILD_EXTMOD

else
# Dummy target needed, because used as prerequisite
include/config/auto.conf: ;
endif # $(dot-config)

# 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

# The arch Makefile can set ARCH_{CPP,A,C}FLAGS to override the default
# values of the respective KBUILD_* variables
ARCH_CPPFLAGS :=
ARCH_AFLAGS :=
ARCH_CFLAGS :=
include arch/$(SRCARCH)/Makefile

KBUILD_CFLAGS	+= $(call cc-option,-fno-delete-null-pointer-checks,)

ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
KBUILD_CFLAGS	+= -Os $(call cc-disable-warning,maybe-uninitialized,)
else
KBUILD_CFLAGS	+= -O2
endif

# Tell gcc to never replace conditional load with a non-conditional one
KBUILD_CFLAGS	+= $(call cc-option,--param=allow-store-data-races=0)

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 += $(call cc-option,-fno-reorder-blocks,) \
                 $(call cc-option,-fno-ipa-cp-clone,) \
                 $(call cc-option,-fno-partial-inlining)
endif

ifneq ($(CONFIG_FRAME_WARN),0)
KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
endif

# Handle stack protector mode.
#
# Since kbuild can potentially perform two passes (first with the old
# .config values and then with updated .config values), we cannot error out
# if a desired compiler option is unsupported. If we were to error, kbuild
# could never get to the second pass and actually notice that we changed
# the option to something that was supported.
#
# Additionally, we don't want to fallback and/or silently change which compiler
# flags will be used, since that leads to producing kernels with different
# security feature characteristics depending on the compiler used. ("But I
# selected CC_STACKPROTECTOR_STRONG! Why did it build with _REGULAR?!")
#
# The middle ground is to warn here so that the failed option is obvious, but
# to let the build fail with bad compiler flags so that we can't produce a
# kernel when there is a CONFIG and compiler mismatch.
#
ifdef CONFIG_CC_STACKPROTECTOR_REGULAR
  stackp-flag := -fstack-protector
  ifeq ($(call cc-option, $(stackp-flag)),)
    $(warning Cannot use CONFIG_CC_STACKPROTECTOR_REGULAR: \
             -fstack-protector not supported by compiler)
  endif
else
ifdef CONFIG_CC_STACKPROTECTOR_STRONG
  stackp-flag := -fstack-protector-strong
  ifeq ($(call cc-option, $(stackp-flag)),)
    $(warning Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: \
	      -fstack-protector-strong not supported by compiler)
  endif
else
  # Force off for distro compilers that enable stack protector by default.
  stackp-flag := $(call cc-option, -fno-stack-protector)
endif
endif
KBUILD_CFLAGS += $(stackp-flag)

ifdef CONFIG_KCOV
  ifeq ($(call cc-option, $(CFLAGS_KCOV)),)
    $(warning Cannot use CONFIG_KCOV: \
             -fsanitize-coverage=trace-pc is not supported by compiler)
    CFLAGS_KCOV =
  endif
endif

ifeq ($(cc-name),clang)
KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)
KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
# Quiet clang warning: comparison of unsigned expression < 0 is always false
KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
# CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the
# source of a reference will be _MergedGlobals and not on of the whitelisted names.
# See modpost pattern 2
KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
else

# This warning generated too much noise in a regular build.
# Use make W=1 to enable this warning (see scripts/Makefile.build)
KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
endif

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

KBUILD_CFLAGS   += $(call cc-option, -fno-var-tracking-assignments)

ifdef CONFIG_DEBUG_INFO
ifdef CONFIG_DEBUG_INFO_SPLIT
KBUILD_CFLAGS   += $(call cc-option, -gsplit-dwarf, -g)
else
KBUILD_CFLAGS	+= -g
endif
KBUILD_AFLAGS	+= -Wa,-gdwarf-2
endif
ifdef CONFIG_DEBUG_INFO_DWARF4
KBUILD_CFLAGS	+= $(call cc-option, -gdwarf-4,)
endif

ifdef CONFIG_DEBUG_INFO_REDUCED
KBUILD_CFLAGS 	+= $(call cc-option, -femit-struct-debug-baseonly) \
		   $(call cc-option,-fno-var-tracking)
endif

ifdef CONFIG_FUNCTION_TRACER
ifndef CC_FLAGS_FTRACE
CC_FLAGS_FTRACE := -pg
endif
export CC_FLAGS_FTRACE
ifdef CONFIG_HAVE_FENTRY
CC_USING_FENTRY	:= $(call cc-option, -mfentry -DCC_USING_FENTRY)
endif
KBUILD_CFLAGS	+= $(CC_FLAGS_FTRACE) $(CC_USING_FENTRY)
KBUILD_AFLAGS	+= $(CC_USING_FENTRY)
ifdef CONFIG_DYNAMIC_FTRACE
	ifdef CONFIG_HAVE_C_RECORDMCOUNT
		BUILD_C_RECORDMCOUNT := y
		export BUILD_C_RECORDMCOUNT
	endif
endif
endif

# We trigger additional mismatches with less inlining
ifdef CONFIG_DEBUG_SECTION_MISMATCH
KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
endif

# arch Makefile may override CC so keep this after arch Makefile is included
NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
CHECKFLAGS     += $(NOSTDINC_FLAGS)

# warn about C99 declaration after statement
KBUILD_CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)

# disable pointer signed / unsigned warnings in gcc 4.0
KBUILD_CFLAGS += $(call cc-disable-warning, pointer-sign)

# disable invalid "can't wrap" optimizations for signed / pointers
KBUILD_CFLAGS	+= $(call cc-option,-fno-strict-overflow)

# conserve stack if available
KBUILD_CFLAGS   += $(call cc-option,-fconserve-stack)

# disallow errors like 'EXPORT_GPL(foo);' with missing header
KBUILD_CFLAGS   += $(call cc-option,-Werror=implicit-int)

# require functions to have arguments in prototypes, not empty 'int foo()'
KBUILD_CFLAGS   += $(call cc-option,-Werror=strict-prototypes)

# Prohibit date/time macros, which would make the build non-deterministic
KBUILD_CFLAGS   += $(call cc-option,-Werror=date-time)

# enforce correct pointer usage
KBUILD_CFLAGS   += $(call cc-option,-Werror=incompatible-pointer-types)

# use the deterministic mode of AR if available
KBUILD_ARFLAGS := $(call ar-option,D)

# check for 'asm goto'
ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC)), y)
	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
	KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
endif

include scripts/Makefile.kasan
include scripts/Makefile.extrawarn
include scripts/Makefile.ubsan

# Add any arch overrides and user supplied CPPFLAGS, AFLAGS and CFLAGS as the
# last assignments
KBUILD_CPPFLAGS += $(ARCH_CPPFLAGS) $(KCPPFLAGS)
KBUILD_AFLAGS   += $(ARCH_AFLAGS)   $(KAFLAGS)
KBUILD_CFLAGS   += $(ARCH_CFLAGS)   $(KCFLAGS)

# Use --build-id when available.
LDFLAGS_BUILD_ID = $(patsubst -Wl$(comma)%,%,\
			      $(call cc-ldoption, -Wl$(comma)--build-id,))
KBUILD_LDFLAGS_MODULE += $(LDFLAGS_BUILD_ID)
LDFLAGS_vmlinux += $(LDFLAGS_BUILD_ID)

ifeq ($(CONFIG_STRIP_ASM_SYMS),y)
LDFLAGS_vmlinux	+= $(call ld-option, -X,)
endif

# 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

#
# INSTALL_MOD_STRIP, if defined, will cause modules to be
# stripped after they are installed.  If INSTALL_MOD_STRIP is '1', then
# the default option --strip-debug will be used.  Otherwise,
# INSTALL_MOD_STRIP value will be used as the options to the strip command.

ifdef INSTALL_MOD_STRIP
ifeq ($(INSTALL_MOD_STRIP),1)
mod_strip_cmd = $(STRIP) --strip-debug
else
mod_strip_cmd = $(STRIP) $(INSTALL_MOD_STRIP)
endif # INSTALL_MOD_STRIP=1
else
mod_strip_cmd = true
endif # INSTALL_MOD_STRIP
export mod_strip_cmd

# CONFIG_MODULE_COMPRESS, if defined, will cause module to be compressed
# after they are installed in agreement with CONFIG_MODULE_COMPRESS_GZIP
# or CONFIG_MODULE_COMPRESS_XZ.

mod_compress_cmd = true
ifdef CONFIG_MODULE_COMPRESS
  ifdef CONFIG_MODULE_COMPRESS_GZIP
    mod_compress_cmd = gzip -n -f
  endif # CONFIG_MODULE_COMPRESS_GZIP
  ifdef CONFIG_MODULE_COMPRESS_XZ
    mod_compress_cmd = xz -f
  endif # CONFIG_MODULE_COMPRESS_XZ
endif # CONFIG_MODULE_COMPRESS
export mod_compress_cmd

# Select initial ramdisk compression format, default is gzip(1).
# This shall be used by the dracut(8) tool while creating an initramfs image.
#
INITRD_COMPRESS-y                  := gzip
INITRD_COMPRESS-$(CONFIG_RD_BZIP2) := bzip2
INITRD_COMPRESS-$(CONFIG_RD_LZMA)  := lzma
INITRD_COMPRESS-$(CONFIG_RD_XZ)    := xz
INITRD_COMPRESS-$(CONFIG_RD_LZO)   := lzo
INITRD_COMPRESS-$(CONFIG_RD_LZ4)   := lz4
# do not export INITRD_COMPRESS, since we didn't actually
# choose a sane default compression above.
# export INITRD_COMPRESS := $(INITRD_COMPRESS-y)

ifdef CONFIG_MODULE_SIG_ALL
$(eval $(call config_filename,MODULE_SIG_KEY))

mod_sign_cmd = scripts/sign-file $(CONFIG_MODULE_SIG_HASH) $(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY) certs/signing_key.x509
else
mod_sign_cmd = true
endif
export mod_sign_cmd


ifeq ($(KBUILD_EXTMOD),)
core-y		+= kernel/ certs/ mm/ fs/ ipc/ security/ crypto/ block/

vmlinux-dirs	:= $(patsubst %/,%,$(filter %/, $(init-y) $(init-m) \
		     $(core-y) $(core-m) $(drivers-y) $(drivers-m) \
		     $(net-y) $(net-m) $(libs-y) $(libs-m) $(virt-y)))

vmlinux-alldirs	:= $(sort $(vmlinux-dirs) $(patsubst %/,%,$(filter %/, \
		     $(init-) $(core-) $(drivers-) $(net-) $(libs-) $(virt-))))

init-y		:= $(patsubst %/, %/built-in.o, $(init-y))
core-y		:= $(patsubst %/, %/built-in.o, $(core-y))
drivers-y	:= $(patsubst %/, %/built-in.o, $(drivers-y))
net-y		:= $(patsubst %/, %/built-in.o, $(net-y))
libs-y1		:= $(patsubst %/, %/lib.a, $(libs-y))
libs-y2		:= $(patsubst %/, %/built-in.o, $(libs-y))
libs-y		:= $(libs-y1) $(libs-y2)
virt-y		:= $(patsubst %/, %/built-in.o, $(virt-y))

# Externally visible symbols (used by link-vmlinux.sh)
export KBUILD_VMLINUX_INIT := $(head-y) $(init-y)
export KBUILD_VMLINUX_MAIN := $(core-y) $(libs-y) $(drivers-y) $(net-y) $(virt-y)
export KBUILD_LDS          := arch/$(SRCARCH)/kernel/vmlinux.lds
export LDFLAGS_vmlinux
# used by scripts/pacmage/Makefile
export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) arch Documentation include samples scripts tools)

vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN)

# Include targets which we want to execute sequentially if the rest of the
# kernel build went well. If CONFIG_TRIM_UNUSED_KSYMS is set, this might be
# evaluated more than once.
PHONY += vmlinux_prereq
vmlinux_prereq: $(vmlinux-deps) FORCE
ifdef CONFIG_HEADERS_CHECK
	$(Q)$(MAKE) -f $(srctree)/Makefile headers_check
endif
ifdef CONFIG_BUILD_DOCSRC
	$(Q)$(MAKE) $(build)=Documentation
endif
ifdef CONFIG_GDB_SCRIPTS
	$(Q)ln -fsn `cd $(srctree) && /bin/pwd`/scripts/gdb/vmlinux-gdb.py
endif
ifdef CONFIG_TRIM_UNUSED_KSYMS
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/adjust_autoksyms.sh \
	  "$(MAKE) KBUILD_MODULES=1 -f $(srctree)/Makefile vmlinux_prereq"
endif

# standalone target for easier testing
include/generated/autoksyms.h: FORCE
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/adjust_autoksyms.sh true

# Final link of vmlinux
      cmd_link-vmlinux = $(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux)
quiet_cmd_link-vmlinux = LINK    $@

vmlinux: scripts/link-vmlinux.sh vmlinux_prereq FORCE
	+$(call if_changed,link-vmlinux)

# Build samples along the rest of the kernel
ifdef CONFIG_SAMPLES
vmlinux-dirs += samples
endif

# The actual objects are generated when descending,
# make sure no implicit rule kicks in
$(sort $(vmlinux-deps)): $(vmlinux-dirs) ;

# Handle descending into subdirectories listed in $(vmlinux-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 += $(vmlinux-dirs)
$(vmlinux-dirs): prepare scripts
	$(Q)$(MAKE) $(build)=$@

define filechk_kernel.release
	echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"
endef

# Store (new) KERNELRELEASE string in include/config/kernel.release
include/config/kernel.release: include/config/auto.conf FORCE
	$(call filechk,kernel.release)


# 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.

# Listed in dependency order
PHONY += prepare archprepare prepare0 prepare1 prepare2 prepare3

# prepare3 is used to check if we are building in a separate output directory,
# and if so do:
# 1) Check that make has not been executed in the kernel src $(srctree)
prepare3: include/config/kernel.release
ifneq ($(KBUILD_SRC),)
	@$(kecho) '  Using $(srctree) as source for kernel'
	$(Q)if [ -f $(srctree)/.config -o -d $(srctree)/include/config ]; then \
		echo >&2 "  $(srctree) is not clean, please run 'make mrproper'"; \
		echo >&2 "  in the '$(srctree)' directory.";\
		/bin/false; \
	fi;
endif

# prepare2 creates a makefile if using a separate output directory
prepare2: prepare3 outputmakefile asm-generic

prepare1: prepare2 $(version_h) include/generated/utsrelease.h \
                   include/config/auto.conf
	$(cmd_crmodverdir)
	$(Q)test -e include/generated/autoksyms.h || \
	    touch   include/generated/autoksyms.h

archprepare: archheaders archscripts prepare1 scripts_basic

prepare0: archprepare
	$(Q)$(MAKE) $(build)=.

# All the preparing..
prepare: prepare0 prepare-objtool

ifdef CONFIG_STACK_VALIDATION
  has_libelf := $(shell echo "int main() {}" | $(HOSTCC) -xc -o /dev/null -lelf - &> /dev/null && echo 1 || echo 0)
  ifeq ($(has_libelf),1)
    objtool_target := tools/objtool FORCE
  else
    $(warning "Cannot use CONFIG_STACK_VALIDATION, please install libelf-dev or elfutils-libelf-devel")
    SKIP_STACK_VALIDATION := 1
    export SKIP_STACK_VALIDATION
  endif
endif

PHONY += prepare-objtool
prepare-objtool: $(objtool_target)

# 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
	(echo \#define LINUX_VERSION_CODE $(shell                         \
	expr $(VERSION) \* 65536 + 0$(PATCHLEVEL) \* 256 + 0$(SUBLEVEL)); \
	echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))';)
endef

$(version_h): $(srctree)/Makefile FORCE
	$(call filechk,version.h)
	$(Q)rm -f $(old_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

# ---------------------------------------------------------------------------
# Firmware install
INSTALL_FW_PATH=$(INSTALL_MOD_PATH)/lib/firmware
export INSTALL_FW_PATH

PHONY += firmware_install
firmware_install:
	@mkdir -p $(objtree)/firmware
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.fwinst obj=firmware __fw_install

# ---------------------------------------------------------------------------
# Kernel headers

#Default location for installed headers
export INSTALL_HDR_PATH = $(objtree)/usr

# If we do an all arch process set dst to asm-$(hdr-arch)
hdr-dst = $(if $(KBUILD_HEADERS), dst=include/asm-$(hdr-arch), dst=include/asm)

PHONY += archheaders
archheaders:

PHONY += archscripts
archscripts:

PHONY += __headers
__headers: $(version_h) scripts_basic asm-generic archheaders archscripts
	$(Q)$(MAKE) $(build)=scripts build_unifdef

PHONY += headers_install_all
headers_install_all:
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/headers.sh install

PHONY += headers_install
headers_install: __headers
	$(if $(wildcard $(srctree)/arch/$(hdr-arch)/include/uapi/asm/Kbuild),, \
	  $(error Headers not exportable for the $(SRCARCH) architecture))
	$(Q)$(MAKE) $(hdr-inst)=include/uapi
	$(Q)$(MAKE) $(hdr-inst)=arch/$(hdr-arch)/include/uapi/asm $(hdr-dst)

PHONY += headers_check_all
headers_check_all: headers_install_all
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/headers.sh check

PHONY += headers_check
headers_check: headers_install
	$(Q)$(MAKE) $(hdr-inst)=include/uapi HDRCHECK=1
	$(Q)$(MAKE) $(hdr-inst)=arch/$(hdr-arch)/include/uapi/asm $(hdr-dst) HDRCHECK=1

# ---------------------------------------------------------------------------
# Kernel selftest

PHONY += kselftest
kselftest:
	$(Q)$(MAKE) -C tools/testing/selftests run_tests

kselftest-clean:
	$(Q)$(MAKE) -C tools/testing/selftests clean

PHONY += kselftest-merge
kselftest-merge:
	$(if $(wildcard $(objtree)/.config),, $(error No .config exists, config your kernel first!))
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/kconfig/merge_config.sh \
		-m $(objtree)/.config \
		$(srctree)/tools/testing/selftests/*/config
	+$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig

# ---------------------------------------------------------------------------
# Modules

ifdef CONFIG_MODULES

# By default, build modules as well

all: modules

# 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: $(vmlinux-dirs) $(if $(KBUILD_BUILTIN),vmlinux) modules.builtin
	$(Q)$(AWK) '!x[$$0]++' $(vmlinux-dirs:%=$(objtree)/%/modules.order) > $(objtree)/modules.order
	@$(kecho) '  Building modules, stage 2.';
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.fwinst obj=firmware __fw_modbuild

modules.builtin: $(vmlinux-dirs:%=%/modules.builtin)
	$(Q)$(AWK) '!x[$$0]++' $^ > $(objtree)/modules.builtin

%/modules.builtin: include/config/auto.conf
	$(Q)$(MAKE) $(modbuiltin)=$*


# Target to prepare building external modules
PHONY += modules_prepare
modules_prepare: prepare scripts

# Target to install modules
PHONY += modules_install
modules_install: _modinst_ _modinst_post

PHONY += _modinst_
_modinst_:
	@rm -rf $(MODLIB)/kernel
	@rm -f $(MODLIB)/source
	@mkdir -p $(MODLIB)/kernel
	@ln -s `cd $(srctree) && /bin/pwd` $(MODLIB)/source
	@if [ ! $(objtree) -ef  $(MODLIB)/build ]; then \
		rm -f $(MODLIB)/build ; \
		ln -s $(CURDIR) $(MODLIB)/build ; \
	fi
	@cp -f $(objtree)/modules.order $(MODLIB)/
	@cp -f $(objtree)/modules.builtin $(MODLIB)/
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst

# This depmod is only for convenience to give the initial
# boot a modules.dep even before / is mounted read-write.  However the
# boot script depmod is the master version.
PHONY += _modinst_post
_modinst_post: _modinst_
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.fwinst obj=firmware __fw_modinst
	$(call cmd,depmod)

ifeq ($(CONFIG_MODULE_SIG), y)
PHONY += modules_sign
modules_sign:
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modsign
endif

else # CONFIG_MODULES

# Modules not configured
# ---------------------------------------------------------------------------

PHONY += modules modules_install
modules modules_install:
	@echo >&2
	@echo >&2 "The present kernel configuration has modules disabled."
	@echo >&2 "Type 'make config' and enable loadable module support."
	@echo >&2 "Then build a kernel with module support enabled."
	@echo >&2
	@exit 1

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_DIRS  += $(MODVERDIR)

# Directories & files removed with 'make mrproper'
MRPROPER_DIRS  += include/config usr/include include/generated          \
		  arch/*/include/generated .tmp_objdiff
MRPROPER_FILES += .config .config.old .version .old_version \
		  Module.symvers tags TAGS cscope* GPATH GTAGS GRTAGS GSYMS \
		  signing_key.pem signing_key.priv signing_key.x509	\
		  x509.genkey extra_certificates signing_key.x509.keyid	\
		  signing_key.x509.signer vmlinux-gdb.py

# clean - Delete most, but leave enough to build external modules
#
clean: rm-dirs  := $(CLEAN_DIRS)
clean: rm-files := $(CLEAN_FILES)
clean-dirs      := $(addprefix _clean_, . $(vmlinux-alldirs) Documentation samples)

PHONY += $(clean-dirs) clean archclean vmlinuxclean
$(clean-dirs):
	$(Q)$(MAKE) $(clean)=$(patsubst _clean_%,%,$@)

vmlinuxclean:
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/link-vmlinux.sh clean

clean: archclean vmlinuxclean

# mrproper - Delete all generated files, including .config
#
mrproper: rm-dirs  := $(wildcard $(MRPROPER_DIRS))
mrproper: rm-files := $(wildcard $(MRPROPER_FILES))
mrproper-dirs      := $(addprefix _mrproper_,Documentation/DocBook scripts)

PHONY += $(mrproper-dirs) mrproper archmrproper
$(mrproper-dirs):
	$(Q)$(MAKE) $(clean)=$(patsubst _mrproper_%,%,$@)

mrproper: clean archmrproper $(mrproper-dirs)
	$(call cmd,rmdirs)
	$(call cmd,rmfiles)

# distclean
#
PHONY += distclean

distclean: mrproper
	@find $(srctree) $(RCS_FIND_IGNORE) \
		\( -name '*.orig' -o -name '*.rej' -o -name '*~' \
		-o -name '*.bak' -o -name '#*#' -o -name '.*.orig' \
		-o -name '.*.rej' -o -name '*%'  -o -name 'core' \) \
		-type f -print | xargs rm -f


# Packaging of the kernel to various formats
# ---------------------------------------------------------------------------
# rpm target kept for backward compatibility
package-dir	:= scripts/package

%src-pkg: FORCE
	$(Q)$(MAKE) $(build)=$(package-dir) $@
%pkg: include/config/kernel.release FORCE
	$(Q)$(MAKE) $(build)=$(package-dir) $@
rpm: include/config/kernel.release FORCE
	$(Q)$(MAKE) $(build)=$(package-dir) $@


# 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  '  firmware_install- Install all firmware to INSTALL_FW_PATH'
	@echo  '                    (default: $$(INSTALL_MOD_PATH)/lib/firmware)'
	@echo  '  dir/            - Build all files in dir and below'
	@echo  '  dir/file.[ois]  - Build specified target only'
	@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: $(INSTALL_HDR_PATH))'; \
	 echo  ''
	@echo  'Static analysers'
	@echo  '  checkstack      - Generate a list of stack hogs'
	@echo  '  namespacecheck  - Name space analysis on compiled kernel'
	@echo  '  versioncheck    - Sanity check on version.h usage'
	@echo  '  includecheck    - Check for duplicate included header files'
	@echo  '  export_report   - List the usages of all exported symbols'
	@echo  '  headers_check   - Sanity check on exported headers'
	@echo  '  headerdep       - Detect inclusion cycles in headers'
	@$(MAKE) -f $(srctree)/scripts/Makefile.help checker-help
	@echo  ''
	@echo  'Kernel selftest'
	@echo  '  kselftest       - Build and run kernel selftest (run as root)'
	@echo  '                    Build, install, and boot kernel before'
	@echo  '                    running kselftest on it'
	@echo  '  kselftest-clean - Remove all generated kselftest files'
	@echo  '  kselftest-merge - Merge all the config dependencies of kselftest to existed'
	@echo  '                    .config.'
	@echo  ''
	@echo  'Kernel packaging:'
	@$(MAKE) $(build)=$(package-dir) help
	@echo  ''
	@echo  'Documentation targets:'
	@$(MAKE) -f $(srctree)/Documentation/DocBook/Makefile dochelp
	@echo  ''
	@echo  'Architecture specific targets ($(SRCARCH)):'
	@$(if $(archhelp),$(archhelp),\
		echo '  No architecture specific help defined for $(SRCARCH)')
	@echo  ''
	@$(if $(boards), \
		$(foreach b, $(boards), \
		printf "  %-24s - 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 all c source with $$CHECK (sparse by default)'
	@echo  '  make C=2   [targets] Force check of all c source with $$CHECK'
	@echo  '  make RECORDMCOUNT_WARN=1 [targets] Warn about ignored mcount sections'
	@echo  '  make W=n   [targets] Enable extra gcc 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  '		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
# ---------------------------------------------------------------------------
%docs: scripts_basic FORCE
	$(Q)$(MAKE) $(build)=scripts build_docproc build_check-lc_ctype
	$(Q)$(MAKE) $(build)=Documentation/DocBook $@

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.
#
# The following are the only valid targets when building external
# modules.
# make M=dir clean     Delete all automatically generated files
# make M=dir modules   Make all modules in specified dir
# make M=dir	       Same as 'make M=dir modules'
# make M=dir modules_install
#                      Install the modules built in the module directory
#                      Assumes install directory is already created

# We are always building modules
KBUILD_MODULES := 1
PHONY += crmodverdir
crmodverdir:
	$(cmd_crmodverdir)

PHONY += $(objtree)/Module.symvers
$(objtree)/Module.symvers:
	@test -e $(objtree)/Module.symvers || ( \
	echo; \
	echo "  WARNING: Symbol version dump $(objtree)/Module.symvers"; \
	echo "           is missing; modules will have no dependencies and modversions."; \
	echo )

module-dirs := $(addprefix _module_,$(KBUILD_EXTMOD))
PHONY += $(module-dirs) modules
$(module-dirs): crmodverdir $(objtree)/Module.symvers
	$(Q)$(MAKE) $(build)=$(patsubst _module_%,%,$@)

modules: $(module-dirs)
	@$(kecho) '  Building modules, stage 2.';
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost

PHONY += modules_install
modules_install: _emodinst_ _emodinst_post

install-dir := $(if $(INSTALL_MOD_DIR),$(INSTALL_MOD_DIR),extra)
PHONY += _emodinst_
_emodinst_:
	$(Q)mkdir -p $(MODLIB)/$(install-dir)
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst

PHONY += _emodinst_post
_emodinst_post: _emodinst_
	$(call cmd,depmod)

clean-dirs := $(addprefix _clean_,$(KBUILD_EXTMOD))

PHONY += $(clean-dirs) clean
$(clean-dirs):
	$(Q)$(MAKE) $(clean)=$(patsubst _clean_%,%,$@)

clean:	rm-dirs := $(MODVERDIR)
clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers

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  ''

# Dummies...
PHONY += prepare scripts
prepare: ;
scripts: ;
endif # KBUILD_EXTMOD

clean: $(clean-dirs)
	$(call cmd,rmdirs)
	$(call cmd,rmfiles)
	@find $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
		\( -name '*.[oas]' -o -name '*.ko' -o -name '.*.cmd' \
		-o -name '*.ko.*' \
		-o -name '*.dwo'  \
		-o -name '*.su'  \
		-o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
		-o -name '*.symtypes' -o -name 'modules.order' \
		-o -name modules.builtin -o -name '.tmp_*.o.*' \
		-o -name '*.gcno' \) -type f -print | xargs rm -f

# Generate tags for editors
# ---------------------------------------------------------------------------
quiet_cmd_tags = GEN     $@
      cmd_tags = $(CONFIG_SHELL) $(srctree)/scripts/tags.sh $@

tags TAGS cscope gtags: FORCE
	$(call cmd,tags)

# Scripts to check various things for consistency
# ---------------------------------------------------------------------------

PHONY += includecheck versioncheck coccicheck namespacecheck 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:
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/$@

namespacecheck:
	$(PERL) $(srctree)/scripts/namespace.pl

export_report:
	$(PERL) $(srctree)/scripts/export_report.pl

endif #ifeq ($(config-targets),1)
endif #ifeq ($(mixed-targets),1)

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) $(src)/scripts/checkstack.pl $(CHECKSTACK_ARCH)

kernelrelease:
	@echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"

kernelversion:
	@echo $(KERNELVERSION)

image_name:
	@echo $(KBUILD_IMAGE)

# Clear a bunch of variables before executing the submake
tools/: FORCE
	$(Q)mkdir -p $(objtree)/tools
	$(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(filter --j% -j,$(MAKEFLAGS))" O=$(shell cd $(objtree) && /bin/pwd) subdir=tools -C $(src)/tools/

tools/%: FORCE
	$(Q)mkdir -p $(objtree)/tools
	$(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(filter --j% -j,$(MAKEFLAGS))" O=$(shell cd $(objtree) && /bin/pwd) subdir=tools -C $(src)/tools/ $*

# Single targets
# ---------------------------------------------------------------------------
# Single targets are compatible with:
# - build with mixed source and output
# - build with separate output dir 'make O=...'
# - external modules
#
#  target-dir => where to store outputfile
#  build-dir  => directory in kernel source tree to use

ifeq ($(KBUILD_EXTMOD),)
        build-dir  = $(patsubst %/,%,$(dir $@))
        target-dir = $(dir $@)
else
        zap-slash=$(filter-out .,$(patsubst %/,%,$(dir $@)))
        build-dir  = $(KBUILD_EXTMOD)$(if $(zap-slash),/$(zap-slash))
        target-dir = $(if $(KBUILD_EXTMOD),$(dir $<),$(dir $@))
endif

%.s: %.c prepare scripts FORCE
	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.i: %.c prepare scripts FORCE
	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.o: %.c prepare scripts FORCE
	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.lst: %.c prepare scripts FORCE
	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.s: %.S prepare scripts FORCE
	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.o: %.S prepare scripts FORCE
	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.symtypes: %.c prepare scripts FORCE
	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)

# Modules
/: prepare scripts FORCE
	$(cmd_crmodverdir)
	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
	$(build)=$(build-dir)
# Make sure the latest headers are built for Documentation
Documentation/: headers_install
%/: prepare scripts FORCE
	$(cmd_crmodverdir)
	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
	$(build)=$(build-dir)
%.ko: prepare scripts FORCE
	$(cmd_crmodverdir)
	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1)   \
	$(build)=$(build-dir) $(@:.ko=.o)
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost

# FIXME Should go into a make.lib or something
# ===========================================================================

quiet_cmd_rmdirs = $(if $(wildcard $(rm-dirs)),CLEAN   $(wildcard $(rm-dirs)))
      cmd_rmdirs = rm -rf $(rm-dirs)

quiet_cmd_rmfiles = $(if $(wildcard $(rm-files)),CLEAN   $(wildcard $(rm-files)))
      cmd_rmfiles = rm -f $(rm-files)

# Run depmod only if we have System.map and depmod is executable
quiet_cmd_depmod = DEPMOD  $(KERNELRELEASE)
      cmd_depmod = $(CONFIG_SHELL) $(srctree)/scripts/depmod.sh $(DEPMOD) \
                   $(KERNELRELEASE) "$(patsubst y,_,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX))"

# Create temporary dir for module support files
# clean it up only when building all modules
cmd_crmodverdir = $(Q)mkdir -p $(MODVERDIR) \
                  $(if $(KBUILD_MODULES),; rm -f $(MODVERDIR)/*)

# read all saved command lines

targets := $(wildcard $(sort $(targets)))
cmd_files := $(wildcard .*.cmd $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))

ifneq ($(cmd_files),)
  $(cmd_files): ;	# Do not try to update included dependency files
  include $(cmd_files)
endif

endif	# skip-makefile

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)