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# The path to Kbuild or Makefile. Kbuild has precedence over Makefile. 45kbuild-dir = $(if $(filter /%,$(src)),$(src),$(srctree)/$(src)) 46kbuild-file = $(or $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Makefile) 47 48### 49# Easy method for doing a status message 50 kecho := : 51 quiet_kecho := echo 52silent_kecho := : 53kecho := $($(quiet)kecho) 54 55### 56# filechk is used to check if the content of a generated file is updated. 57# Sample usage: 58# 59# filechk_sample = echo $(KERNELRELEASE) 60# version.h: FORCE 61# $(call filechk,sample) 62# 63# The rule defined shall write to stdout the content of the new file. 64# The existing file will be compared with the new one. 65# - If no file exist it is created 66# - If the content differ the new file is used 67# - If they are equal no change, and no timestamp update 68define filechk 69 $(check-FORCE) 70 $(Q)set -e; \ 71 mkdir -p $(dir $@); \ 72 trap "rm -f $(dot-target).tmp" EXIT; \ 73 { $(filechk_$(1)); } > $(dot-target).tmp; \ 74 if [ ! -r $@ ] || ! cmp -s $@ $(dot-target).tmp; then \ 75 $(kecho) ' UPD $@'; \ 76 mv -f $(dot-target).tmp $@; \ 77 fi 78endef 79 80### 81# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj= 82# Usage: 83# $(Q)$(MAKE) $(build)=dir 84build := -f $(srctree)/scripts/Makefile.build obj 85 86### 87# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.dtbinst obj= 88# Usage: 89# $(Q)$(MAKE) $(dtbinst)=dir 90dtbinst := -f $(srctree)/scripts/Makefile.dtbinst obj 91 92### 93# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.clean obj= 94# Usage: 95# $(Q)$(MAKE) $(clean)=dir 96clean := -f $(srctree)/scripts/Makefile.clean obj 97 98# echo command. 99# Short version is used, if $(quiet) equals `quiet_', otherwise full one. 100echo-cmd = $(if $($(quiet)cmd_$(1)),\ 101 echo ' $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';) 102 103# sink stdout for 'make -s' 104 redirect := 105 quiet_redirect := 106silent_redirect := exec >/dev/null; 107 108# Delete the target on interruption 109# 110# GNU Make automatically deletes the target if it has already been changed by 111# the interrupted recipe. So, you can safely stop the build by Ctrl-C (Make 112# will delete incomplete targets), and resume it later. 113# 114# However, this does not work when the stderr is piped to another program, like 115# $ make >&2 | tee log 116# Make dies with SIGPIPE before cleaning the targets. 117# 118# To address it, we clean the target in signal traps. 119# 120# Make deletes the target when it catches SIGHUP, SIGINT, SIGQUIT, SIGTERM. 121# So, we cover them, and also SIGPIPE just in case. 122# 123# Of course, this is unneeded for phony targets. 124delete-on-interrupt = \ 125 $(if $(filter-out $(PHONY), $@), \ 126 $(foreach sig, HUP INT QUIT TERM PIPE, \ 127 trap 'rm -f $@; trap - $(sig); kill -s $(sig) $$$$' $(sig);)) 128 129# printing commands 130cmd = @set -e; $(echo-cmd) $($(quiet)redirect) $(delete-on-interrupt) $(cmd_$(1)) 131 132### 133# if_changed - execute command if any prerequisite is newer than 134# target, or command line has changed 135# if_changed_dep - as if_changed, but uses fixdep to reveal dependencies 136# including used config symbols 137# if_changed_rule - as if_changed but execute rule instead 138# See Documentation/kbuild/makefiles.rst for more info 139 140ifneq ($(KBUILD_NOCMDDEP),1) 141# Check if both commands are the same including their order. Result is empty 142# string if equal. User may override this check using make KBUILD_NOCMDDEP=1 143cmd-check = $(filter-out $(subst $(space),$(space_escape),$(strip $(cmd_$@))), \ 144 $(subst $(space),$(space_escape),$(strip $(cmd_$1)))) 145else 146cmd-check = $(if $(strip $(cmd_$@)),,1) 147endif 148 149# Replace >$< with >$$< to preserve $ when reloading the .cmd file 150# (needed for make) 151# Replace >#< with >$(pound)< to avoid starting a comment in the .cmd file 152# (needed for make) 153# Replace >'< with >'\''< to be able to enclose the whole string in '...' 154# (needed for the shell) 155make-cmd = $(call escsq,$(subst $(pound),$$(pound),$(subst $$,$$$$,$(cmd_$(1))))) 156 157# Find any prerequisites that are newer than target or that do not exist. 158# (This is not true for now; $? should contain any non-existent prerequisites, 159# but it does not work as expected when .SECONDARY is present. This seems a bug 160# of GNU Make.) 161# PHONY targets skipped in both cases. 162newer-prereqs = $(filter-out $(PHONY),$?) 163 164# It is a typical mistake to forget the FORCE prerequisite. Check it here so 165# no more breakage will slip in. 166check-FORCE = $(if $(filter FORCE, $^),,$(warning FORCE prerequisite is missing)) 167 168if-changed-cond = $(newer-prereqs)$(cmd-check)$(check-FORCE) 169 170# Execute command if command has changed or prerequisite(s) are updated. 171if_changed = $(if $(if-changed-cond),$(cmd_and_savecmd),@:) 172 173cmd_and_savecmd = \ 174 $(cmd); \ 175 printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd 176 177# Execute the command and also postprocess generated .d dependencies file. 178if_changed_dep = $(if $(if-changed-cond),$(cmd_and_fixdep),@:) 179 180cmd_and_fixdep = \ 181 $(cmd); \ 182 scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).cmd;\ 183 rm -f $(depfile) 184 185# Usage: $(call if_changed_rule,foo) 186# Will check if $(cmd_foo) or any of the prerequisites changed, 187# and if so will execute $(rule_foo). 188if_changed_rule = $(if $(if-changed-cond),$(rule_$(1)),@:) 189 190### 191# why - tell why a target got built 192# enabled by make V=2 193# Output (listed in the order they are checked): 194# (1) - due to target is PHONY 195# (2) - due to target missing 196# (3) - due to: file1.h file2.h 197# (4) - due to command line change 198# (5) - due to missing .cmd file 199# (6) - due to target not in $(targets) 200# (1) PHONY targets are always build 201# (2) No target, so we better build it 202# (3) Prerequisite is newer than target 203# (4) The command line stored in the file named dir/.target.cmd 204# differed from actual command line. This happens when compiler 205# options changes 206# (5) No dir/.target.cmd file (used to store command line) 207# (6) No dir/.target.cmd file and target not listed in $(targets) 208# This is a good hint that there is a bug in the kbuild file 209ifeq ($(KBUILD_VERBOSE),2) 210why = \ 211 $(if $(filter $@, $(PHONY)),- due to target is PHONY, \ 212 $(if $(wildcard $@), \ 213 $(if $(newer-prereqs),- due to: $(newer-prereqs), \ 214 $(if $(cmd-check), \ 215 $(if $(cmd_$@),- due to command line change, \ 216 $(if $(filter $@, $(targets)), \ 217 - due to missing .cmd file, \ 218 - due to $(notdir $@) not in $$(targets) \ 219 ) \ 220 ) \ 221 ) \ 222 ), \ 223 - due to target missing \ 224 ) \ 225 ) 226 227echo-why = $(call escsq, $(strip $(why))) 228endif 229 230############################################################################### 231 232# delete partially updated (i.e. corrupted) files on error 233.DELETE_ON_ERROR: 234 235# do not delete intermediate files automatically 236.SECONDARY: 237