1#### 2# kbuild: Generic definitions 3 4# Convinient variables 5comma := , 6squote := ' 7empty := 8space := $(empty) $(empty) 9 10### 11# The temporary file to save gcc -MD generated dependencies must not 12# contain a comma 13depfile = $(subst $(comma),_,$(@D)/.$(@F).d) 14 15### 16# Escape single quote for use in echo statements 17escsq = $(subst $(squote),'\$(squote)',$1) 18 19### 20# filechk is used to check if the content of a generated file is updated. 21# Sample usage: 22# define filechk_sample 23# echo $KERNELRELEASE 24# endef 25# version.h : Makefile 26# $(call filechk,sample) 27# The rule defined shall write to stdout the content of the new file. 28# The existing file will be compared with the new one. 29# - If no file exist it is created 30# - If the content differ the new file is used 31# - If they are equal no change, and no timestamp update 32# - stdin is piped in from the first prerequisite ($<) so one has 33# to specify a valid file as first prerequisite (often the kbuild file) 34define filechk 35 $(Q)set -e; \ 36 echo ' CHK $@'; \ 37 mkdir -p $(dir $@); \ 38 $(filechk_$(1)) < $< > $@.tmp; \ 39 if [ -r $@ ] && cmp -s $@ $@.tmp; then \ 40 rm -f $@.tmp; \ 41 else \ 42 echo ' UPD $@'; \ 43 mv -f $@.tmp $@; \ 44 fi 45endef 46 47### 48# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj= 49# Usage: 50# $(Q)$(MAKE) $(build)=dir 51build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj 52 53# If quiet is set, only print short version of command 54cmd = @$(if $($(quiet)cmd_$(1)),\ 55 echo ' $(call escsq,$($(quiet)cmd_$(1)))' &&) $(cmd_$(1)) 56 57# Add $(obj)/ for paths that is not absolute 58objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o))) 59 60### 61# if_changed - execute command if any prerequisite is newer than 62# target, or command line has changed 63# if_changed_dep - as if_changed, but uses fixdep to reveal dependencies 64# including used config symbols 65# if_changed_rule - as if_changed but execute rule instead 66# See Documentation/kbuild/makefiles.txt for more info 67 68ifneq ($(KBUILD_NOCMDDEP),1) 69# Check if both arguments has same arguments. Result in empty string if equal 70# User may override this check using make KBUILD_NOCMDDEP=1 71arg-check = $(strip $(filter-out $(1), $(2)) $(filter-out $(2), $(1)) ) 72endif 73 74# echo command. Short version is $(quiet) equals quiet, otherwise full command 75echo-cmd = $(if $($(quiet)cmd_$(1)), \ 76 echo ' $(call escsq,$($(quiet)cmd_$(1)))';) 77 78# function to only execute the passed command if necessary 79# >'< substitution is for echo to work, >$< substitution to preserve $ when reloading .cmd file 80# note: when using inline perl scripts [perl -e '...$$t=1;...'] in $(cmd_xxx) double $$ your perl vars 81# 82if_changed = $(if $(strip $? $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ), \ 83 @set -e; \ 84 $(echo-cmd) \ 85 $(cmd_$(1)); \ 86 echo 'cmd_$@ := $(subst $$,$$$$,$(call escsq,$(cmd_$(1))))' > $(@D)/.$(@F).cmd) 87 88# execute the command and also postprocess generated .d dependencies 89# file 90if_changed_dep = $(if $(strip $? $(filter-out FORCE $(wildcard $^),$^)\ 91 $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ), \ 92 @set -e; \ 93 $(echo-cmd) \ 94 $(cmd_$(1)); \ 95 scripts/basic/fixdep $(depfile) $@ '$(subst $$,$$$$,$(call escsq,$(cmd_$(1))))' > $(@D)/.$(@F).tmp; \ 96 rm -f $(depfile); \ 97 mv -f $(@D)/.$(@F).tmp $(@D)/.$(@F).cmd) 98 99# Usage: $(call if_changed_rule,foo) 100# will check if $(cmd_foo) changed, or any of the prequisites changed, 101# and if so will execute $(rule_foo) 102if_changed_rule = $(if $(strip $? $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ),\ 103 @set -e; \ 104 $(rule_$(1))) 105