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