--- /dev/null
+####
+# kbuild: Generic definitions
+
+# Convinient variables
+comma := ,
+squote := '
+empty :=
+space := $(empty) $(empty)
+
+###
+# The temporary file to save gcc -MD generated dependencies must not
+# contain a comma
+depfile = $(subst $(comma),_,$(@D)/.$(@F).d)
+
+###
+# Escape single quote for use in echo statements
+escsq = $(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 $@; \
+ fi
+endef
+
+######
+# 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 -malign
+cc-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)=dir
+build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj
+
+# Prefix -I with $(srctree) if it is not an absolute path
+addtree = $(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)),$(o)))
+
+# If quiet is set, only print short version of command
+cmd = @$(echo-cmd) $(cmd_$(1))
+
+# Add $(obj)/ for paths that is 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 in empty string if equal
+# User may override this check using make KBUILD_NOCMDDEP=1
+arg-check = $(strip $(filter-out $(1), $(2)) $(filter-out $(2), $(1)) )
+endif
+
+# echo command. Short version is $(quiet) equals quiet, otherwise full command
+echo-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
+# file
+if_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)))
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