1#### 2# kbuild: Generic definitions 3 4# Convenient constants 5comma := , 6squote := ' 7empty := 8space := $(empty) $(empty) 9 10### 11# Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o 12dot-target = $(dir $@).$(notdir $@) 13 14### 15# The temporary file to save gcc -MD generated dependencies must not 16# contain a comma 17depfile = $(subst $(comma),_,$(dot-target).d) 18 19### 20# filename of target with directory and extension stripped 21basetarget = $(basename $(notdir $@)) 22 23### 24# Escape single quote for use in echo statements 25escsq = $(subst $(squote),'\$(squote)',$1) 26 27### 28# filechk is used to check if the content of a generated file is updated. 29# Sample usage: 30# define filechk_sample 31# echo $KERNELRELEASE 32# endef 33# version.h : Makefile 34# $(call filechk,sample) 35# The rule defined shall write to stdout the content of the new file. 36# The existing file will be compared with the new one. 37# - If no file exist it is created 38# - If the content differ the new file is used 39# - If they are equal no change, and no timestamp update 40# - stdin is piped in from the first prerequisite ($<) so one has 41# to specify a valid file as first prerequisite (often the kbuild file) 42define filechk 43 $(Q)set -e; \ 44 echo ' CHK $@'; \ 45 mkdir -p $(dir $@); \ 46 $(filechk_$(1)) < $< > $@.tmp; \ 47 if [ -r $@ ] && cmp -s $@ $@.tmp; then \ 48 rm -f $@.tmp; \ 49 else \ 50 echo ' UPD $@'; \ 51 mv -f $@.tmp $@; \ 52 fi 53endef 54 55###### 56# gcc support functions 57# See documentation in Documentation/kbuild/makefiles.txt 58 59# checker-shell 60# Usage: option = $(call checker-shell,$(CC)...-o $$OUT,option-ok,otherwise) 61# Exit code chooses option. $$OUT is safe location for needless output. 62define checker-shell 63$(shell set -e; \ 64 DIR=$(KBUILD_EXTMOD); \ 65 cd $${DIR:-$(objtree)}; \ 66 OUT=$$PWD/.$$$$.null; \ 67 if $(1) >/dev/null 2>&1; \ 68 then echo "$(2)"; \ 69 else echo "$(3)"; \ 70 fi; \ 71 rm -f $$OUT) 72endef 73 74# as-option 75# Usage: cflags-y += $(call as-option,-Wa$(comma)-isa=foo,) 76as-option = $(call checker-shell,\ 77 $(CC) $(CFLAGS) $(1) -c -xassembler /dev/null -o $$OUT,$(1),$(2)) 78 79# as-instr 80# Usage: cflags-y += $(call as-instr,instr,option1,option2) 81as-instr = $(call checker-shell,\ 82 printf "$(1)" | $(CC) $(AFLAGS) -c -xassembler -o $$OUT -,$(2),$(3)) 83 84# cc-option 85# Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586) 86cc-option = $(call checker-shell,\ 87 $(CC) $(CFLAGS) $(if $(3),$(3),$(1)) -S -xc /dev/null -o $$OUT,$(1),$(2)) 88 89# cc-option-yn 90# Usage: flag := $(call cc-option-yn,-march=winchip-c6) 91cc-option-yn = $(call cc-option,"y","n",$(1)) 92 93# cc-option-align 94# Prefix align with either -falign or -malign 95cc-option-align = $(subst -functions=0,,\ 96 $(call cc-option,-falign-functions=0,-malign-functions=0)) 97 98# cc-version 99# Usage gcc-ver := $(call cc-version,$(CC)) 100cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC)) 101 102# cc-ifversion 103# Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1) 104cc-ifversion = $(shell [ $(call cc-version, $(CC)) $(1) $(2) ] && echo $(3)) 105 106# ld-option 107# Usage: ldflags += $(call ld-option, -Wl$(comma)--hash-style=both) 108ld-option = $(call checker-shell,\ 109 $(CC) $(1) -nostdlib -xc /dev/null -o $$OUT,$(1),$(2)) 110 111###### 112 113# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj= 114# Usage: 115# $(Q)$(MAKE) $(build)=dir 116build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj 117 118# Prefix -I with $(srctree) if it is not an absolute path, 119# add original to the end 120addtree = $(if \ 121 $(filter-out -I/%,$(1)),$(patsubst -I%,-I$(srctree)/%,$(1))) $(1) 122 123# Find all -I options and call addtree 124flags = $(foreach o,$($(1)),\ 125 $(if $(filter -I%,$(o)),$(call addtree,$(o)),$(o))) 126 127# echo command. 128# Short version is used, if $(quiet) equals `quiet_', otherwise full one. 129echo-cmd = $(if $($(quiet)cmd_$(1)),\ 130 echo ' $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';) 131 132# printing commands 133cmd = @$(echo-cmd) $(cmd_$(1)) 134 135# Add $(obj)/ for paths that are not absolute 136objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o))) 137 138### 139# if_changed - execute command if any prerequisite is newer than 140# target, or command line has changed 141# if_changed_dep - as if_changed, but uses fixdep to reveal dependencies 142# including used config symbols 143# if_changed_rule - as if_changed but execute rule instead 144# See Documentation/kbuild/makefiles.txt for more info 145 146ifneq ($(KBUILD_NOCMDDEP),1) 147# Check if both arguments has same arguments. Result is empty string, if equal. 148# User may override this check using make KBUILD_NOCMDDEP=1 149arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \ 150 $(filter-out $(cmd_$@), $(cmd_$(1))) ) 151endif 152 153# >'< substitution is for echo to work, 154# >$< substitution to preserve $ when reloading .cmd file 155# note: when using inline perl scripts [perl -e '...$$t=1;...'] 156# in $(cmd_xxx) double $$ your perl vars 157make-cmd = $(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1))))) 158 159# Find any prerequisites that is newer than target or that does not exist. 160# PHONY targets skipped in both cases. 161any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^) 162 163# Execute command if command has changed or prerequisite(s) are updated. 164# 165if_changed = $(if $(strip $(any-prereq) $(arg-check)), \ 166 @set -e; \ 167 $(echo-cmd) $(cmd_$(1)); \ 168 echo 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd) 169 170# Execute the command and also postprocess generated .d dependencies file. 171# 172if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ), \ 173 @set -e; \ 174 $(echo-cmd) $(cmd_$(1)); \ 175 scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\ 176 rm -f $(depfile); \ 177 mv -f $(dot-target).tmp $(dot-target).cmd) 178 179# Will check if $(cmd_foo) changed, or any of the prerequisites changed, 180# and if so will execute $(rule_foo). 181# Usage: $(call if_changed_rule,foo) 182# 183if_changed_rule = $(if $(strip $(any-prereq) $(arg-check) ), \ 184 @set -e; \ 185 $(rule_$(1))) 186 187### 188# why - tell why a a target got build 189# enabled by make V=2 190# Output (listed in the order they are checked): 191# (1) - due to target is PHONY 192# (2) - due to target missing 193# (3) - due to: file1.h file2.h 194# (4) - due to command line change 195# (5) - due to missing .cmd file 196# (6) - due to target not in $(targets) 197# (1) PHONY targets are always build 198# (2) No target, so we better build it 199# (3) Prerequisite is newer than target 200# (4) The command line stored in the file named dir/.target.cmd 201# differed from actual command line. This happens when compiler 202# options changes 203# (5) No dir/.target.cmd file (used to store command line) 204# (6) No dir/.target.cmd file and target not listed in $(targets) 205# This is a good hint that there is a bug in the kbuild file 206ifeq ($(KBUILD_VERBOSE),2) 207why = \ 208 $(if $(filter $@, $(PHONY)),- due to target is PHONY, \ 209 $(if $(wildcard $@), \ 210 $(if $(strip $(any-prereq)),- due to: $(any-prereq), \ 211 $(if $(arg-check), \ 212 $(if $(cmd_$@),- due to command line change, \ 213 $(if $(filter $@, $(targets)), \ 214 - due to missing .cmd file, \ 215 - due to $(notdir $@) not in $$(targets) \ 216 ) \ 217 ) \ 218 ) \ 219 ), \ 220 - due to target missing \ 221 ) \ 222 ) 223 224echo-why = $(call escsq, $(strip $(why))) 225endif 226