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