##### kbuild: Generic definitions # Convinient variablescomma   := ,squote  := 'empty   :=space   := $(empty) $(empty) #### The temporary file to save gcc -MD generated dependencies must not# contain a commadepfile = $(subst $(comma),_,$(@D)/.$(@F).d) #### Escape single quote for use in echo statementsescsq = $(subst $(squote),'\$(squote)',$1) #### 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;				\	echo '  CHK     $@';			\	mkdir -p $(dir $@);			\	$(filechk_$(1)) < $< > $@.tmp;		\	if [ -r $@ ] && cmp -s $@ $@.tmp; then	\		rm -f $@.tmp;			\	else					\		echo '  UPD     $@';		\		mv -f $@.tmp $@;		\	fiendef ####### gcc support functions# See documentation in Documentation/kbuild/makefiles.txt # as-option# Usage: cflags-y += $(call as-option, -Wa$(comma)-isa=foo,) as-option = $(shell if $(CC) $(CFLAGS) $(1) -Wa,-Z -c -o /dev/null \	     -xassembler /dev/null > /dev/null 2>&1; then echo "$(1)"; \	     else echo "$(2)"; fi ;) # cc-option# Usage: cflags-y += $(call cc-option, -march=winchip-c6, -march=i586) cc-option = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \             > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;) # cc-option-yn# Usage: flag := $(call cc-option-yn, -march=winchip-c6)cc-option-yn = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \                > /dev/null 2>&1; then echo "y"; else echo "n"; fi;) # cc-option-align# Prefix align with either -falign or -maligncc-option-align = $(subst -functions=0,,\	$(call cc-option,-falign-functions=0,-malign-functions=0)) # cc-version# Usage gcc-ver := $(call cc-version, $(CC))cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh \              $(if $(1), $(1), $(CC))) # cc-ifversion# Usage:  EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)cc-ifversion = $(shell if [ $(call cc-version, $(CC)) $(1) $(2) ]; then \                       echo $(3); fi;) #### Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=# Usage:# $(Q)$(MAKE) $(build)=dirbuild := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj # Prefix -I with $(srctree) if it is not an absolute pathaddtree = $(if $(filter-out -I/%,$(1)),$(patsubst -I%,-I$(srctree)/%,$(1))) $(1)# Find all -I options and call addtreeflags = $(foreach o,$($(1)),$(if $(filter -I%,$(o)),$(call addtree,$(o)),$(o))) # If quiet is set, only print short version of commandcmd = @$(echo-cmd) $(cmd_$(1)) # Add $(obj)/ for paths that is not absoluteobjectify = $(foreach o,$(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 in empty string if equal# User may override this check using make KBUILD_NOCMDDEP=1arg-check = $(strip $(filter-out $(1), $(2)) $(filter-out $(2), $(1)) )endif # echo command. Short version is $(quiet) equals quiet, otherwise full commandecho-cmd = $(if $($(quiet)cmd_$(1)), \	echo '  $(call escsq,$($(quiet)cmd_$(1)))';) make-cmd = $(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1))))) # function to only execute the passed command if necessary# >'< substitution is for echo to work, >$< substitution to preserve $ when reloading .cmd file# note: when using inline perl scripts [perl -e '...$$t=1;...'] in $(cmd_xxx) double $$ your perl vars#if_changed = $(if $(strip $(filter-out $(PHONY),$?)          \		$(call arg-check, $(cmd_$(1)), $(cmd_$@)) ), \	@set -e; \	$(echo-cmd) $(cmd_$(1)); \	echo 'cmd_$@ := $(make-cmd)' > $(@D)/.$(@F).cmd) # execute the command and also postprocess generated .d dependencies# fileif_changed_dep = $(if $(strip $(filter-out $(PHONY),$?)  \		$(filter-out FORCE $(wildcard $^),$^)    \	$(call arg-check, $(cmd_$(1)), $(cmd_$@)) ),     \	@set -e; \	$(echo-cmd) $(cmd_$(1)); \	scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(@D)/.$(@F).tmp; \	rm -f $(depfile); \	mv -f $(@D)/.$(@F).tmp $(@D)/.$(@F).cmd) # Usage: $(call if_changed_rule,foo)# will check if $(cmd_foo) changed, or any of the prequisites changed,# and if so will execute $(rule_foo)if_changed_rule = $(if $(strip $(filter-out $(PHONY),$?)            \			$(call arg-check, $(cmd_$(1)), $(cmd_$@)) ),\			@set -e; \			$(rule_$(1)))