1# SPDX-License-Identifier: GPL-2.0 2#### 3# kbuild: Generic definitions 4 5# Convenient variables 6comma := , 7quote := " 8squote := ' 9empty := 10space := $(empty) $(empty) 11space_escape := _-_SPACE_-_ 12pound := \# 13 14### 15# Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o 16dot-target = $(dir $@).$(notdir $@) 17 18### 19# Name of target with a '.tmp_' as filename prefix. foo/bar.o => foo/.tmp_bar.o 20tmp-target = $(dir $@).tmp_$(notdir $@) 21 22### 23# The temporary file to save gcc -MMD generated dependencies must not 24# contain a comma 25depfile = $(subst $(comma),_,$(dot-target).d) 26 27### 28# filename of target with directory and extension stripped 29basetarget = $(basename $(notdir $@)) 30 31### 32# real prerequisites without phony targets 33real-prereqs = $(filter-out $(PHONY), $^) 34 35### 36# Escape single quote for use in echo statements 37escsq = $(subst $(squote),'\$(squote)',$1) 38 39### 40# Quote a string to pass it to C files. foo => '"foo"' 41stringify = $(squote)$(quote)$1$(quote)$(squote) 42 43### 44# Easy method for doing a status message 45 kecho := : 46 quiet_kecho := echo 47silent_kecho := : 48kecho := $($(quiet)kecho) 49 50### 51# filechk is used to check if the content of a generated file is updated. 52# Sample usage: 53# 54# filechk_sample = echo $(KERNELRELEASE) 55# version.h: FORCE 56# $(call filechk,sample) 57# 58# The rule defined shall write to stdout the content of the new file. 59# The existing file will be compared with the new one. 60# - If no file exist it is created 61# - If the content differ the new file is used 62# - If they are equal no change, and no timestamp update 63define filechk 64 $(check-FORCE) 65 $(Q)set -e; \ 66 mkdir -p $(dir $@); \ 67 trap "rm -f $(dot-target).tmp" EXIT; \ 68 { $(filechk_$(1)); } > $(dot-target).tmp; \ 69 if [ ! -r $@ ] || ! cmp -s $@ $(dot-target).tmp; then \ 70 $(kecho) ' UPD $@'; \ 71 mv -f $(dot-target).tmp $@; \ 72 fi 73endef 74 75### 76# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj= 77# Usage: 78# $(Q)$(MAKE) $(build)=dir 79build := -f $(srctree)/scripts/Makefile.build obj 80 81### 82# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.dtbinst obj= 83# Usage: 84# $(Q)$(MAKE) $(dtbinst)=dir 85dtbinst := -f $(srctree)/scripts/Makefile.dtbinst obj 86 87### 88# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.clean obj= 89# Usage: 90# $(Q)$(MAKE) $(clean)=dir 91clean := -f $(srctree)/scripts/Makefile.clean obj 92 93# echo command. 94# Short version is used, if $(quiet) equals `quiet_', otherwise full one. 95echo-cmd = $(if $($(quiet)cmd_$(1)),\ 96 echo ' $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';) 97 98# sink stdout for 'make -s' 99 redirect := 100 quiet_redirect := 101silent_redirect := exec >/dev/null; 102 103# printing commands 104cmd = @set -e; $(echo-cmd) $($(quiet)redirect) $(cmd_$(1)) 105 106### 107# if_changed - execute command if any prerequisite is newer than 108# target, or command line has changed 109# if_changed_dep - as if_changed, but uses fixdep to reveal dependencies 110# including used config symbols 111# if_changed_rule - as if_changed but execute rule instead 112# See Documentation/kbuild/makefiles.rst for more info 113 114ifneq ($(KBUILD_NOCMDDEP),1) 115# Check if both commands are the same including their order. Result is empty 116# string if equal. User may override this check using make KBUILD_NOCMDDEP=1 117cmd-check = $(filter-out $(subst $(space),$(space_escape),$(strip $(cmd_$@))), \ 118 $(subst $(space),$(space_escape),$(strip $(cmd_$1)))) 119else 120cmd-check = $(if $(strip $(cmd_$@)),,1) 121endif 122 123# Replace >$< with >$$< to preserve $ when reloading the .cmd file 124# (needed for make) 125# Replace >#< with >$(pound)< to avoid starting a comment in the .cmd file 126# (needed for make) 127# Replace >'< with >'\''< to be able to enclose the whole string in '...' 128# (needed for the shell) 129make-cmd = $(call escsq,$(subst $(pound),$$(pound),$(subst $$,$$$$,$(cmd_$(1))))) 130 131# Find any prerequisites that are newer than target or that do not exist. 132# (This is not true for now; $? should contain any non-existent prerequisites, 133# but it does not work as expected when .SECONDARY is present. This seems a bug 134# of GNU Make.) 135# PHONY targets skipped in both cases. 136newer-prereqs = $(filter-out $(PHONY),$?) 137 138# It is a typical mistake to forget the FORCE prerequisite. Check it here so 139# no more breakage will slip in. 140check-FORCE = $(if $(filter FORCE, $^),,$(warning FORCE prerequisite is missing)) 141 142if-changed-cond = $(newer-prereqs)$(cmd-check)$(check-FORCE) 143 144# Execute command if command has changed or prerequisite(s) are updated. 145if_changed = $(if $(if-changed-cond),$(cmd_and_savecmd),@:) 146 147cmd_and_savecmd = \ 148 $(cmd); \ 149 printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd 150 151# Execute the command and also postprocess generated .d dependencies file. 152if_changed_dep = $(if $(if-changed-cond),$(cmd_and_fixdep),@:) 153 154cmd_and_fixdep = \ 155 $(cmd); \ 156 scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).cmd;\ 157 rm -f $(depfile) 158 159# Usage: $(call if_changed_rule,foo) 160# Will check if $(cmd_foo) or any of the prerequisites changed, 161# and if so will execute $(rule_foo). 162if_changed_rule = $(if $(if-changed-cond),$(rule_$(1)),@:) 163 164### 165# why - tell why a target got built 166# enabled by make V=2 167# Output (listed in the order they are checked): 168# (1) - due to target is PHONY 169# (2) - due to target missing 170# (3) - due to: file1.h file2.h 171# (4) - due to command line change 172# (5) - due to missing .cmd file 173# (6) - due to target not in $(targets) 174# (1) PHONY targets are always build 175# (2) No target, so we better build it 176# (3) Prerequisite is newer than target 177# (4) The command line stored in the file named dir/.target.cmd 178# differed from actual command line. This happens when compiler 179# options changes 180# (5) No dir/.target.cmd file (used to store command line) 181# (6) No dir/.target.cmd file and target not listed in $(targets) 182# This is a good hint that there is a bug in the kbuild file 183ifeq ($(KBUILD_VERBOSE),2) 184why = \ 185 $(if $(filter $@, $(PHONY)),- due to target is PHONY, \ 186 $(if $(wildcard $@), \ 187 $(if $(newer-prereqs),- due to: $(newer-prereqs), \ 188 $(if $(cmd-check), \ 189 $(if $(cmd_$@),- due to command line change, \ 190 $(if $(filter $@, $(targets)), \ 191 - due to missing .cmd file, \ 192 - due to $(notdir $@) not in $$(targets) \ 193 ) \ 194 ) \ 195 ) \ 196 ), \ 197 - due to target missing \ 198 ) \ 199 ) 200 201echo-why = $(call escsq, $(strip $(why))) 202endif 203 204############################################################################### 205 206# delete partially updated (i.e. corrupted) files on error 207.DELETE_ON_ERROR: 208 209# do not delete intermediate files automatically 210.SECONDARY: 211