[mirror_ubuntu-artful-kernel.git] / scripts / Kbuild.include

####
# kbuild: Generic definitions

# Convenient variables
comma   := ,
squote  := '
empty   :=
space   := $(empty) $(empty)

###
# Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
dot-target = $(dir $@).$(notdir $@)

###
# The temporary file to save gcc -MD generated dependencies must not
# contain a comma
depfile = $(subst $(comma),_,$(dot-target).d)

###
# filename of target with directory and extension stripped
basetarget = $(basename $(notdir $@))

###
# filename of first prerequisite with directory and extension stripped
baseprereq = $(basename $(notdir $<))

###
# Escape single quote for use in echo statements
escsq = $(subst $(squote),'\$(squote)',$1)

###
# Easy method for doing a status message
       kecho := :
 quiet_kecho := echo
silent_kecho := :
kecho := $($(quiet)kecho)

###
# filechk is used to check if the content of a generated file is updated.
# Sample usage:
# define filechk_sample
#	echo $KERNELRELEASE
# endef
# version.h : Makefile
#	$(call filechk,sample)
# The rule defined shall write to stdout the content of the new file.
# The existing file will be compared with the new one.
# - If no file exist it is created
# - If the content differ the new file is used
# - If they are equal no change, and no timestamp update
# - stdin is piped in from the first prerequisite ($<) so one has
#   to specify a valid file as first prerequisite (often the kbuild file)
define filechk
	$(Q)set -e;				\
	$(kecho) '  CHK     $@';		\
	mkdir -p $(dir $@);			\
	$(filechk_$(1)) < $< > $@.tmp;		\
	if [ -r $@ ] && cmp -s $@ $@.tmp; then	\
		rm -f $@.tmp;			\
	else					\
		$(kecho) '  UPD     $@';	\
		mv -f $@.tmp $@;		\
	fi
endef

######
# gcc support functions
# See documentation in Documentation/kbuild/makefiles.txt

# cc-cross-prefix
# Usage: CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu- m68k-linux-)
# Return first prefix where a prefix$(CC) is found in PATH.
# If no $(CC) found in PATH with listed prefixes return nothing
cc-cross-prefix =  \
	$(word 1, $(foreach c,$(1),                                   \
		$(shell set -e;                                       \
		if (which $(strip $(c))$(CC)) > /dev/null 2>&1 ; then \
			echo $(c);                                    \
		fi)))

# output directory for tests below
TMPOUT := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/)

# try-run
# Usage: option = $(call try-run, $(CC)...-o "$$TMP",option-ok,otherwise)
# Exit code chooses option. "$$TMP" is can be used as temporary file and
# is automatically cleaned up.
try-run = $(shell set -e;		\
	TMP="$(TMPOUT).$$$$.tmp";	\
	TMPO="$(TMPOUT).$$$$.o";	\
	if ($(1)) >/dev/null 2>&1;	\
	then echo "$(2)";		\
	else echo "$(3)";		\
	fi;				\
	rm -f "$$TMP" "$$TMPO")

# as-option
# Usage: cflags-y += $(call as-option,-Wa$(comma)-isa=foo,)

as-option = $(call try-run,\
	$(CC) $(KBUILD_CFLAGS) $(1) -c -xassembler /dev/null -o "$$TMP",$(1),$(2))

# as-instr
# Usage: cflags-y += $(call as-instr,instr,option1,option2)

as-instr = $(call try-run,\
	/bin/echo -e "$(1)" | $(CC) $(KBUILD_AFLAGS) -c -xassembler -o "$$TMP" -,$(2),$(3))

# cc-option
# Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)

cc-option = $(call try-run,\
	$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -xc /dev/null -o "$$TMP",$(1),$(2))

# cc-option-yn
# Usage: flag := $(call cc-option-yn,-march=winchip-c6)
cc-option-yn = $(call try-run,\
	$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -xc /dev/null -o "$$TMP",y,n)

# cc-option-align
# Prefix align with either -falign or -malign
cc-option-align = $(subst -functions=0,,\
	$(call cc-option,-falign-functions=0,-malign-functions=0))

# cc-disable-warning
# Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable)
cc-disable-warning = $(call try-run,\
	$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -xc /dev/null -o "$$TMP",-Wno-$(strip $(1)))

# cc-version
# Usage gcc-ver := $(call cc-version)
cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC))

# cc-fullversion
# Usage gcc-ver := $(call cc-fullversion)
cc-fullversion = $(shell $(CONFIG_SHELL) \
	$(srctree)/scripts/gcc-version.sh -p $(CC))

# cc-ifversion
# Usage:  EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
cc-ifversion = $(shell [ $(call cc-version, $(CC)) $(1) $(2) ] && echo $(3))

# cc-ldoption
# Usage: ldflags += $(call cc-ldoption, -Wl$(comma)--hash-style=both)
cc-ldoption = $(call try-run,\
	$(CC) $(1) -nostdlib -xc /dev/null -o "$$TMP",$(1),$(2))

# ld-option
# Usage: LDFLAGS += $(call ld-option, -X)
ld-option = $(call try-run,\
	$(CC) /dev/null -c -o "$$TMPO" ; $(LD) $(1) "$$TMPO" -o "$$TMP",$(1),$(2))

# ar-option
# Usage: KBUILD_ARFLAGS := $(call ar-option,D)
# Important: no spaces around options
ar-option = $(call try-run, $(AR) rc$(1) "$$TMP",$(1),$(2))

######

###
# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
# Usage:
# $(Q)$(MAKE) $(build)=dir
build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj

###
# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.modbuiltin obj=
# Usage:
# $(Q)$(MAKE) $(modbuiltin)=dir
modbuiltin := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.modbuiltin obj

# Prefix -I with $(srctree) if it is not an absolute path.
# skip if -I has no parameter
addtree = $(if $(patsubst -I%,%,$(1)), \
$(if $(filter-out -I/%,$(1)),$(patsubst -I%,-I$(srctree)/%,$(1))) $(1))

# Find all -I options and call addtree
flags = $(foreach o,$($(1)),$(if $(filter -I%,$(o)),$(call addtree,$(o)),$(o)))

# echo command.
# Short version is used, if $(quiet) equals `quiet_', otherwise full one.
echo-cmd = $(if $($(quiet)cmd_$(1)),\
	echo '  $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)

# printing commands
cmd = @$(echo-cmd) $(cmd_$(1))

# Add $(obj)/ for paths that are not absolute
objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o)))

###
# if_changed      - execute command if any prerequisite is newer than
#                   target, or command line has changed
# if_changed_dep  - as if_changed, but uses fixdep to reveal dependencies
#                   including used config symbols
# if_changed_rule - as if_changed but execute rule instead
# See Documentation/kbuild/makefiles.txt for more info

ifneq ($(KBUILD_NOCMDDEP),1)
# Check if both arguments has same arguments. Result is empty string if equal.
# User may override this check using make KBUILD_NOCMDDEP=1
arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \
                    $(filter-out $(cmd_$@),   $(cmd_$(1))) )
else
arg-check = $(if $(strip $(cmd_$@)),,1)
endif

# >'< substitution is for echo to work,
# >$< substitution to preserve $ when reloading .cmd file
# note: when using inline perl scripts [perl -e '...$$t=1;...']
# in $(cmd_xxx) double $$ your perl vars
make-cmd = $(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1)))))

# Find any prerequisites that is newer than target or that does not exist.
# PHONY targets skipped in both cases.
any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^)

# Execute command if command has changed or prerequisite(s) are updated.
#
if_changed = $(if $(strip $(any-prereq) $(arg-check)),                       \
	@set -e;                                                             \
	$(echo-cmd) $(cmd_$(1));                                             \
	echo 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd)

# Execute the command and also postprocess generated .d dependencies file.
if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ),                  \
	@set -e;                                                             \
	$(echo-cmd) $(cmd_$(1));                                             \
	scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
	rm -f $(depfile);                                                    \
	mv -f $(dot-target).tmp $(dot-target).cmd)

# Usage: $(call if_changed_rule,foo)
# Will check if $(cmd_foo) or any of the prerequisites changed,
# and if so will execute $(rule_foo).
if_changed_rule = $(if $(strip $(any-prereq) $(arg-check) ),                 \
	@set -e;                                                             \
	$(rule_$(1)))

###
# why - tell why a a target got build
#       enabled by make V=2
#       Output (listed in the order they are checked):
#          (1) - due to target is PHONY
#          (2) - due to target missing
#          (3) - due to: file1.h file2.h
#          (4) - due to command line change
#          (5) - due to missing .cmd file
#          (6) - due to target not in $(targets)
# (1) PHONY targets are always build
# (2) No target, so we better build it
# (3) Prerequisite is newer than target
# (4) The command line stored in the file named dir/.target.cmd
#     differed from actual command line. This happens when compiler
#     options changes
# (5) No dir/.target.cmd file (used to store command line)
# (6) No dir/.target.cmd file and target not listed in $(targets)
#     This is a good hint that there is a bug in the kbuild file
ifeq ($(KBUILD_VERBOSE),2)
why =                                                                        \
    $(if $(filter $@, $(PHONY)),- due to target is PHONY,                    \
        $(if $(wildcard $@),                                                 \
            $(if $(strip $(any-prereq)),- due to: $(any-prereq),             \
                $(if $(arg-check),                                           \
                    $(if $(cmd_$@),- due to command line change,             \
                        $(if $(filter $@, $(targets)),                       \
                            - due to missing .cmd file,                      \
                            - due to $(notdir $@) not in $$(targets)         \
                         )                                                   \
                     )                                                       \
                 )                                                           \
             ),                                                              \
             - due to target missing                                         \
         )                                                                   \
     )

echo-why = $(call escsq, $(strip $(why)))
endif
Commit	Line	Data
8ec4b4ff SR	1	####
	2	# kbuild: Generic definitions
	3
beda9f3a	4	# Convenient variables
8ec4b4ff	5	comma := ,
d51bfb78	6	squote := '
8ec4b4ff SR	7	empty :=
	8	space := $(empty) $(empty)
	9
48f1f058 SR	10	###
	11	# Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
	12	dot-target = $(dir $@).$(notdir $@)
	13
8ec4b4ff SR	14	###
	15	# The temporary file to save gcc -MD generated dependencies must not
	16	# contain a comma
48f1f058	17	depfile = $(subst $(comma),_,$(dot-target).d)
8ec4b4ff	18
5e8d780d SR	19	###
	20	# filename of target with directory and extension stripped
	21	basetarget = $(basename $(notdir $@))
	22
e0318d85 AL	23	###
	24	# filename of first prerequisite with directory and extension stripped
	25	baseprereq = $(basename $(notdir $<))
	26
d51bfb78 SR	27	###
	28	# Escape single quote for use in echo statements
	29	escsq = $(subst $(squote),'\$(squote)',$1)
	30
5410ecc0 MF	31	###
	32	# Easy method for doing a status message
	33	kecho := :
	34	quiet_kecho := echo
	35	silent_kecho := :
	36	kecho := $($(quiet)kecho)
	37
8ec4b4ff SR	38	###
	39	# filechk is used to check if the content of a generated file is updated.
	40	# Sample usage:
	41	# define filechk_sample
	42	# echo $KERNELRELEASE
	43	# endef
	44	# version.h : Makefile
	45	# $(call filechk,sample)
	46	# The rule defined shall write to stdout the content of the new file.
	47	# The existing file will be compared with the new one.
	48	# - If no file exist it is created
	49	# - If the content differ the new file is used
	50	# - If they are equal no change, and no timestamp update
	51	# - stdin is piped in from the first prerequisite ($<) so one has
	52	# to specify a valid file as first prerequisite (often the kbuild file)
	53	define filechk
	54	$(Q)set -e; \
fd54f502	55	$(kecho) ' CHK $@'; \
8ec4b4ff SR	56	mkdir -p $(dir $@); \
	57	$(filechk_$(1)) < $< > $@.tmp; \
	58	if [ -r $@ ] && cmp -s $@ $@.tmp; then \
	59	rm -f $@.tmp; \
	60	else \
fd54f502	61	$(kecho) ' UPD $@'; \
8ec4b4ff SR	62	mv -f $@.tmp $@; \
	63	fi
	64	endef
	65
20a468b5	66	######
9d6e7a70	67	# gcc support functions
20a468b5 SR	68	# See documentation in Documentation/kbuild/makefiles.txt
20a468b5 SR	69
910b4046 SR	70	# cc-cross-prefix
	71	# Usage: CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu- m68k-linux-)
	72	# Return first prefix where a prefix$(CC) is found in PATH.
	73	# If no $(CC) found in PATH with listed prefixes return nothing
	74	cc-cross-prefix = \
	75	$(word 1, $(foreach c,$(1), \
	76	$(shell set -e; \
	77	if (which $(strip $(c))$(CC)) > /dev/null 2>&1 ; then \
	78	echo $(c); \
	79	fi)))
	80
beda9f3a RZ	81	# output directory for tests below
	82	TMPOUT := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/)
	83
	84	# try-run
	85	# Usage: option = $(call try-run, $(CC)...-o "$$TMP",option-ok,otherwise)
	86	# Exit code chooses option. "$$TMP" is can be used as temporary file and
	87	# is automatically cleaned up.
	88	try-run = $(shell set -e; \
	89	TMP="$(TMPOUT).$$$$.tmp"; \
691ef3e7	90	TMPO="$(TMPOUT).$$$$.o"; \
beda9f3a RZ	91	if ($(1)) >/dev/null 2>&1; \
	92	then echo "$(2)"; \
	93	else echo "$(3)"; \
	94	fi; \
691ef3e7	95	rm -f "$$TMP" "$$TMPO")
347a00fb	96
20a468b5	97	# as-option
bff288c1	98	# Usage: cflags-y += $(call as-option,-Wa$(comma)-isa=foo,)
beda9f3a RZ	99
beda9f3a RZ	100	as-option = $(call try-run,\
a0f97e06	101	$(CC) $(KBUILD_CFLAGS) $(1) -c -xassembler /dev/null -o "$$TMP",$(1),$(2))
20a468b5	102
e2414910	103	# as-instr
bff288c1	104	# Usage: cflags-y += $(call as-instr,instr,option1,option2)
beda9f3a RZ	105
beda9f3a RZ	106	as-instr = $(call try-run,\
a3ee9470	107	/bin/echo -e "$(1)" \| $(CC) $(KBUILD_AFLAGS) -c -xassembler -o "$$TMP" -,$(2),$(3))
e2414910	108
20a468b5	109	# cc-option
bff288c1	110	# Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
beda9f3a RZ	111
beda9f3a RZ	112	cc-option = $(call try-run,\
c47efe55	113	$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -xc /dev/null -o "$$TMP",$(1),$(2))
20a468b5 SR	114
20a468b5 SR	115	# cc-option-yn
bff288c1	116	# Usage: flag := $(call cc-option-yn,-march=winchip-c6)
beda9f3a	117	cc-option-yn = $(call try-run,\
c47efe55	118	$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -xc /dev/null -o "$$TMP",y,n)
20a468b5 SR	119
	120	# cc-option-align
	121	# Prefix align with either -falign or -malign
	122	cc-option-align = $(subst -functions=0,,\
beda9f3a	123	$(call cc-option,-falign-functions=0,-malign-functions=0))
20a468b5	124
8417da6f MM	125	# cc-disable-warning
	126	# Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable)
	127	cc-disable-warning = $(call try-run,\
	128	$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -xc /dev/null -o "$$TMP",-Wno-$(strip $(1)))
	129
20a468b5	130	# cc-version
0ab2a272	131	# Usage gcc-ver := $(call cc-version)
8eb3afe0	132	cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC))
20a468b5	133
0ab2a272 SB	134	# cc-fullversion
	135	# Usage gcc-ver := $(call cc-fullversion)
	136	cc-fullversion = $(shell $(CONFIG_SHELL) \
	137	$(srctree)/scripts/gcc-version.sh -p $(CC))
	138
20a468b5 SR	139	# cc-ifversion
20a468b5 SR	140	# Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
5de043f4	141	cc-ifversion = $(shell [ $(call cc-version, $(CC)) $(1) $(2) ] && echo $(3))
20a468b5	142
f86fd306 SR	143	# cc-ldoption
	144	# Usage: ldflags += $(call cc-ldoption, -Wl$(comma)--hash-style=both)
	145	cc-ldoption = $(call try-run,\
beda9f3a	146	$(CC) $(1) -nostdlib -xc /dev/null -o "$$TMP",$(1),$(2))
5de043f4	147
691ef3e7 SR	148	# ld-option
	149	# Usage: LDFLAGS += $(call ld-option, -X)
	150	ld-option = $(call try-run,\
	151	$(CC) /dev/null -c -o "$$TMPO" ; $(LD) $(1) "$$TMPO" -o "$$TMP",$(1),$(2))
	152
40df759e MM	153	# ar-option
	154	# Usage: KBUILD_ARFLAGS := $(call ar-option,D)
	155	# Important: no spaces around options
	156	ar-option = $(call try-run, $(AR) rc$(1) "$$TMP",$(1),$(2))
	157
5de043f4	158	######
0b0bf7a3	159
beda9f3a	160	###
8ec4b4ff SR	161	# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
	162	# Usage:
	163	# $(Q)$(MAKE) $(build)=dir
	164	build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj
	165
bc081dd6 MM	166	###
	167	# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.modbuiltin obj=
	168	# Usage:
	169	# $(Q)$(MAKE) $(modbuiltin)=dir
	170	modbuiltin := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.modbuiltin obj
	171
beda9f3a	172	# Prefix -I with $(srctree) if it is not an absolute path.
5b91c33c SR	173	# skip if -I has no parameter
	174	addtree = $(if $(patsubst -I%,%,$(1)), \
	175	$(if $(filter-out -I/%,$(1)),$(patsubst -I%,-I$(srctree)/%,$(1))) $(1))
5de043f4	176
d9df92e2	177	# Find all -I options and call addtree
beda9f3a	178	flags = $(foreach o,$($(1)),$(if $(filter -I%,$(o)),$(call addtree,$(o)),$(o)))
d9df92e2	179
5de043f4 OV	180	# echo command.
5de043f4 OV	181	# Short version is used, if $(quiet) equals `quiet_', otherwise full one.
bff288c1	182	echo-cmd = $(if $($(quiet)cmd_$(1)),\
5de043f4 OV	183	echo ' $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
	184
	185	# printing commands
6176aa9a	186	cmd = @$(echo-cmd) $(cmd_$(1))
8ec4b4ff	187
5de043f4	188	# Add $(obj)/ for paths that are not absolute
bff288c1	189	objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o)))
0a504f25	190
8ec4b4ff	191	###
5de043f4	192	# if_changed - execute command if any prerequisite is newer than
8ec4b4ff SR	193	# target, or command line has changed
	194	# if_changed_dep - as if_changed, but uses fixdep to reveal dependencies
	195	# including used config symbols
	196	# if_changed_rule - as if_changed but execute rule instead
	197	# See Documentation/kbuild/makefiles.txt for more info
	198
	199	ifneq ($(KBUILD_NOCMDDEP),1)
beda9f3a	200	# Check if both arguments has same arguments. Result is empty string if equal.
8ec4b4ff	201	# User may override this check using make KBUILD_NOCMDDEP=1
48f1f058 SR	202	arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \
48f1f058 SR	203	$(filter-out $(cmd_$@), $(cmd_$(1))) )
c4d5ee13 MM	204	else
c4d5ee13 MM	205	arg-check = $(if $(strip $(cmd_$@)),,1)
8ec4b4ff SR	206	endif
8ec4b4ff SR	207
48f1f058 SR	208	# >'< substitution is for echo to work,
	209	# >$< substitution to preserve $ when reloading .cmd file
	210	# note: when using inline perl scripts [perl -e '...$$t=1;...']
	211	# in $(cmd_xxx) double $$ your perl vars
6176aa9a JB	212	make-cmd = $(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1)))))
6176aa9a JB	213
48f1f058 SR	214	# Find any prerequisites that is newer than target or that does not exist.
	215	# PHONY targets skipped in both cases.
	216	any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^)
	217
5de043f4	218	# Execute command if command has changed or prerequisite(s) are updated.
4f193362	219	#
48f1f058 SR	220	if_changed = $(if $(strip $(any-prereq) $(arg-check)), \
	221	@set -e; \
	222	$(echo-cmd) $(cmd_$(1)); \
	223	echo 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd)
8ec4b4ff	224
5de043f4	225	# Execute the command and also postprocess generated .d dependencies file.
48f1f058 SR	226	if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ), \
	227	@set -e; \
	228	$(echo-cmd) $(cmd_$(1)); \
	229	scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
	230	rm -f $(depfile); \
	231	mv -f $(dot-target).tmp $(dot-target).cmd)
8ec4b4ff SR	232
8ec4b4ff SR	233	# Usage: $(call if_changed_rule,foo)
beda9f3a RZ	234	# Will check if $(cmd_foo) or any of the prerequisites changed,
beda9f3a RZ	235	# and if so will execute $(rule_foo).
48f1f058 SR	236	if_changed_rule = $(if $(strip $(any-prereq) $(arg-check) ), \
	237	@set -e; \
	238	$(rule_$(1)))
	239
45d506bd SR	240	###
	241	# why - tell why a a target got build
	242	# enabled by make V=2
	243	# Output (listed in the order they are checked):
	244	# (1) - due to target is PHONY
	245	# (2) - due to target missing
	246	# (3) - due to: file1.h file2.h
	247	# (4) - due to command line change
	248	# (5) - due to missing .cmd file
	249	# (6) - due to target not in $(targets)
	250	# (1) PHONY targets are always build
	251	# (2) No target, so we better build it
	252	# (3) Prerequisite is newer than target
	253	# (4) The command line stored in the file named dir/.target.cmd
	254	# differed from actual command line. This happens when compiler
	255	# options changes
	256	# (5) No dir/.target.cmd file (used to store command line)
	257	# (6) No dir/.target.cmd file and target not listed in $(targets)
	258	# This is a good hint that there is a bug in the kbuild file
	259	ifeq ($(KBUILD_VERBOSE),2)
	260	why = \
	261	$(if $(filter $@, $(PHONY)),- due to target is PHONY, \
	262	$(if $(wildcard $@), \
	263	$(if $(strip $(any-prereq)),- due to: $(any-prereq), \
	264	$(if $(arg-check), \
	265	$(if $(cmd_$@),- due to command line change, \
	266	$(if $(filter $@, $(targets)), \
	267	- due to missing .cmd file, \
	268	- due to $(notdir $@) not in $$(targets) \
	269	) \
	270	) \
	271	) \
	272	), \
	273	- due to target missing \
	274	) \
	275	)
	276
	277	echo-why = $(call escsq, $(strip $(why)))
	278	endif