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# gcc support functions 49# See documentation in Documentation/kbuild/makefiles.txt 50 51# as-option 52# Usage: cflags-y += $(call as-option, -Wa$(comma)-isa=foo,) 53 54as-option = $(shell if $(CC) $(CFLAGS) $(1) -Wa,-Z -c -o /dev/null \ 55 -xassembler /dev/null > /dev/null 2>&1; then echo "$(1)"; \ 56 else echo "$(2)"; fi ;) 57 58# cc-option 59# Usage: cflags-y += $(call cc-option, -march=winchip-c6, -march=i586) 60 61cc-option = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \ 62 > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;) 63 64# cc-option-yn 65# Usage: flag := $(call cc-option-yn, -march=winchip-c6) 66cc-option-yn = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \ 67 > /dev/null 2>&1; then echo "y"; else echo "n"; fi;) 68 69# cc-option-align 70# Prefix align with either -falign or -malign 71cc-option-align = $(subst -functions=0,,\ 72 $(call cc-option,-falign-functions=0,-malign-functions=0)) 73 74# cc-version 75# Usage gcc-ver := $(call cc-version, $(CC)) 76cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh \ 77 $(if $(1), $(1), $(CC))) 78 79# cc-ifversion 80# Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1) 81cc-ifversion = $(shell if [ $(call cc-version, $(CC)) $(1) $(2) ]; then \ 82 echo $(3); fi;) 83 84### 85# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj= 86# Usage: 87# $(Q)$(MAKE) $(build)=dir 88build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj 89 90# If quiet is set, only print short version of command 91cmd = @$(echo-cmd) $(cmd_$(1)) 92 93# Add $(obj)/ for paths that is not absolute 94objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o))) 95 96### 97# if_changed - execute command if any prerequisite is newer than 98# target, or command line has changed 99# if_changed_dep - as if_changed, but uses fixdep to reveal dependencies 100# including used config symbols 101# if_changed_rule - as if_changed but execute rule instead 102# See Documentation/kbuild/makefiles.txt for more info 103 104ifneq ($(KBUILD_NOCMDDEP),1) 105# Check if both arguments has same arguments. Result in empty string if equal 106# User may override this check using make KBUILD_NOCMDDEP=1 107arg-check = $(strip $(filter-out $(1), $(2)) $(filter-out $(2), $(1)) ) 108endif 109 110# echo command. Short version is $(quiet) equals quiet, otherwise full command 111echo-cmd = $(if $($(quiet)cmd_$(1)), \ 112 echo ' $(call escsq,$($(quiet)cmd_$(1)))';) 113 114make-cmd = $(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1))))) 115 116# function to only execute the passed command if necessary 117# >'< substitution is for echo to work, >$< substitution to preserve $ when reloading .cmd file 118# note: when using inline perl scripts [perl -e '...$$t=1;...'] in $(cmd_xxx) double $$ your perl vars 119# 120if_changed = $(if $(strip $(filter-out $(PHONY),$?) \ 121 $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ), \ 122 @set -e; \ 123 $(echo-cmd) $(cmd_$(1)); \ 124 echo 'cmd_$@ := $(make-cmd)' > $(@D)/.$(@F).cmd) 125 126# execute the command and also postprocess generated .d dependencies 127# file 128if_changed_dep = $(if $(strip $(filter-out $(PHONY),$?) \ 129 $(filter-out FORCE $(wildcard $^),$^) \ 130 $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ), \ 131 @set -e; \ 132 $(echo-cmd) $(cmd_$(1)); \ 133 scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(@D)/.$(@F).tmp; \ 134 rm -f $(depfile); \ 135 mv -f $(@D)/.$(@F).tmp $(@D)/.$(@F).cmd) 136 137# Usage: $(call if_changed_rule,foo) 138# will check if $(cmd_foo) changed, or any of the prequisites changed, 139# and if so will execute $(rule_foo) 140if_changed_rule = $(if $(strip $(filter-out $(PHONY),$?) \ 141 $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ),\ 142 @set -e; \ 143 $(rule_$(1))) 144