1 # SPDX-License-Identifier: GPL-2.0
2 ####
3 # kbuild: Generic definitions
4
5 # Convenient variables
6 comma := ,
7 quote := "
8 squote := '
9 empty :=
10 space := $(empty) $(empty)
11 space_escape := _-_SPACE_-_
12 pound := \#
13 define newline
14
15
16 endef
17
18 ###
19 # Comparison macros.
20 # Usage: $(call test-lt, $(CONFIG_LLD_VERSION), 150000)
21 #
22 # Use $(intcmp ...) if supported. (Make >= 4.4)
23 # Otherwise, fall back to the 'test' shell command.
24 ifeq ($(intcmp 1,0,,,y),y)
25 test-ge = $(intcmp $(strip $1)0, $(strip $2)0,,y,y)
26 test-gt = $(intcmp $(strip $1)0, $(strip $2)0,,,y)
27 else
28 test-ge = $(shell test $(strip $1)0 -ge $(strip $2)0 && echo y)
29 test-gt = $(shell test $(strip $1)0 -gt $(strip $2)0 && echo y)
30 endif
31 test-le = $(call test-ge, $2, $1)
32 test-lt = $(call test-gt, $2, $1)
33
34 ###
35 # Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
36 dot-target = $(dir $@).$(notdir $@)
37
38 ###
39 # Name of target with a '.tmp_' as filename prefix. foo/bar.o => foo/.tmp_bar.o
40 tmp-target = $(dir $@).tmp_$(notdir $@)
41
42 ###
43 # The temporary file to save gcc -MMD generated dependencies must not
44 # contain a comma
45 depfile = $(subst $(comma),_,$(dot-target).d)
46
47 ###
48 # filename of target with directory and extension stripped
49 basetarget = $(basename $(notdir $@))
50
51 ###
52 # real prerequisites without phony targets
53 real-prereqs = $(filter-out $(PHONY), $^)
54
55 ###
56 # Escape single quote for use in echo statements
57 escsq = $(subst $(squote),'\$(squote)',$1)
58
59 ###
60 # Quote a string to pass it to C files. foo => '"foo"'
61 stringify = $(squote)$(quote)$1$(quote)$(squote)
62
63 ###
64 # The path to Kbuild or Makefile. Kbuild has precedence over Makefile.
65 kbuild-file = $(or $(wildcard $(src)/Kbuild),$(src)/Makefile)
66
67 ###
68 # Read a file, replacing newlines with spaces
69 #
70 # Make 4.2 or later can read a file by using its builtin function.
71 ifneq ($(filter-out 4.0 4.1, $(MAKE_VERSION)),)
72 read-file = $(subst $(newline),$(space),$(file < $1))
73 else
74 read-file = $(shell cat $1 2>/dev/null)
75 endif
76
77 ###
78 # Easy method for doing a status message
79 kecho := :
80 quiet_kecho := echo
81 silent_kecho := :
82 kecho := $($(quiet)kecho)
83
84 ###
85 # filechk is used to check if the content of a generated file is updated.
86 # Sample usage:
87 #
88 # filechk_sample = echo $(KERNELRELEASE)
89 # version.h: FORCE
90 # $(call filechk,sample)
91 #
92 # The rule defined shall write to stdout the content of the new file.
93 # The existing file will be compared with the new one.
94 # - If no file exist it is created
95 # - If the content differ the new file is used
96 # - If they are equal no change, and no timestamp update
97 define filechk
98 $(check-FORCE)
99 $(Q)set -e; \
100 mkdir -p $(dir $@); \
101 trap "rm -f $(tmp-target)" EXIT; \
102 { $(filechk_$(1)); } > $(tmp-target); \
103 if [ ! -r $@ ] || ! cmp -s $@ $(tmp-target); then \
104 $(kecho) ' UPD $@'; \
105 mv -f $(tmp-target) $@; \
106 fi
107 endef
108
109 ###
110 # Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
111 # Usage:
112 # $(Q)$(MAKE) $(build)=dir
113 build := -f $(srctree)/scripts/Makefile.build obj
114
115 ###
116 # Shorthand for $(Q)$(MAKE) -f scripts/Makefile.clean obj=
117 # Usage:
118 # $(Q)$(MAKE) $(clean)=dir
119 clean := -f $(srctree)/scripts/Makefile.clean obj
120
121 # pring log
122 #
123 # If quiet is "silent_", print nothing and sink stdout
124 # If quiet is "quiet_", print short log
125 # If quiet is empty, print short log and whole command
126 silent_log_print = exec >/dev/null;
127 quiet_log_print = $(if $(quiet_cmd_$1), echo ' $(call escsq,$(quiet_cmd_$1)$(why))';)
128 log_print = echo '$(pound) $(call escsq,$(or $(quiet_cmd_$1),cmd_$1 $@)$(why))'; \
129 echo ' $(call escsq,$(cmd_$1))';
130
131 # Delete the target on interruption
132 #
133 # GNU Make automatically deletes the target if it has already been changed by
134 # the interrupted recipe. So, you can safely stop the build by Ctrl-C (Make
135 # will delete incomplete targets), and resume it later.
136 #
137 # However, this does not work when the stderr is piped to another program, like
138 # $ make >&2 | tee log
139 # Make dies with SIGPIPE before cleaning the targets.
140 #
141 # To address it, we clean the target in signal traps.
142 #
143 # Make deletes the target when it catches SIGHUP, SIGINT, SIGQUIT, SIGTERM.
144 # So, we cover them, and also SIGPIPE just in case.
145 #
146 # Of course, this is unneeded for phony targets.
147 delete-on-interrupt = \
148 $(if $(filter-out $(PHONY), $@), \
149 $(foreach sig, HUP INT QUIT TERM PIPE, \
150 trap 'rm -f $@; trap - $(sig); kill -s $(sig) $$$$' $(sig);))
151
152 # print and execute commands
153 cmd = @$(if $(cmd_$(1)),set -e; $($(quiet)log_print) $(delete-on-interrupt) $(cmd_$(1)),:)
154
155 ###
156 # if_changed - execute command if any prerequisite is newer than
157 # target, or command line has changed
158 # if_changed_dep - as if_changed, but uses fixdep to reveal dependencies
159 # including used config symbols
160 # if_changed_rule - as if_changed but execute rule instead
161 # See Documentation/kbuild/makefiles.rst for more info
162
163 ifneq ($(KBUILD_NOCMDDEP),1)
164 # Check if both commands are the same including their order. Result is empty
165 # string if equal. User may override this check using make KBUILD_NOCMDDEP=1
166 # If the target does not exist, the *.cmd file should not be included so
167 # $(savedcmd_$@) gets empty. Then, target will be built even if $(newer-prereqs)
168 # happens to become empty.
169 cmd-check = $(filter-out $(subst $(space),$(space_escape),$(strip $(savedcmd_$@))), \
170 $(subst $(space),$(space_escape),$(strip $(cmd_$1))))
171 else
172 # We still need to detect missing targets.
173 cmd-check = $(if $(strip $(savedcmd_$@)),,1)
174 endif
175
176 # Replace >$< with >$$< to preserve $ when reloading the .cmd file
177 # (needed for make)
178 # Replace >#< with >$(pound)< to avoid starting a comment in the .cmd file
179 # (needed for make)
180 # Replace >'< with >'\''< to be able to enclose the whole string in '...'
181 # (needed for the shell)
182 make-cmd = $(call escsq,$(subst $(pound),$$(pound),$(subst $$,$$$$,$(cmd_$(1)))))
183
184 # Find any prerequisites that are newer than target or that do not exist.
185 # PHONY targets skipped in both cases.
186 # If there is no prerequisite other than phony targets, $(newer-prereqs) becomes
187 # empty even if the target does not exist. cmd-check saves this corner case.
188 newer-prereqs = $(filter-out $(PHONY),$?)
189
190 # It is a typical mistake to forget the FORCE prerequisite. Check it here so
191 # no more breakage will slip in.
192 check-FORCE = $(if $(filter FORCE, $^),,$(warning FORCE prerequisite is missing))
193
194 if-changed-cond = $(newer-prereqs)$(cmd-check)$(check-FORCE)
195
196 # Execute command if command has changed or prerequisite(s) are updated.
197 if_changed = $(if $(if-changed-cond),$(cmd_and_savecmd),@:)
198
199 cmd_and_savecmd = \
200 $(cmd); \
201 printf '%s\n' 'savedcmd_$@ := $(make-cmd)' > $(dot-target).cmd
202
203 # Execute the command and also postprocess generated .d dependencies file.
204 if_changed_dep = $(if $(if-changed-cond),$(cmd_and_fixdep),@:)
205
206 cmd_and_fixdep = \
207 $(cmd); \
208 scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).cmd;\
209 rm -f $(depfile)
210
211 # Usage: $(call if_changed_rule,foo)
212 # Will check if $(cmd_foo) or any of the prerequisites changed,
213 # and if so will execute $(rule_foo).
214 if_changed_rule = $(if $(if-changed-cond),$(rule_$(1)),@:)
215
216 ###
217 # why - tell why a target got built
218 # enabled by make V=2
219 # Output (listed in the order they are checked):
220 # (1) - due to target is PHONY
221 # (2) - due to target missing
222 # (3) - due to: file1.h file2.h
223 # (4) - due to command line change
224 # (5) - due to missing .cmd file
225 # (6) - due to target not in $(targets)
226 # (1) PHONY targets are always build
227 # (2) No target, so we better build it
228 # (3) Prerequisite is newer than target
229 # (4) The command line stored in the file named dir/.target.cmd
230 # differed from actual command line. This happens when compiler
231 # options changes
232 # (5) No dir/.target.cmd file (used to store command line)
233 # (6) No dir/.target.cmd file and target not listed in $(targets)
234 # This is a good hint that there is a bug in the kbuild file
235 ifneq ($(findstring 2, $(KBUILD_VERBOSE)),)
236 _why = \
237 $(if $(filter $@, $(PHONY)),- due to target is PHONY, \
238 $(if $(wildcard $@), \
239 $(if $(newer-prereqs),- due to: $(newer-prereqs), \
240 $(if $(cmd-check), \
241 $(if $(savedcmd_$@),- due to command line change, \
242 $(if $(filter $@, $(targets)), \
243 - due to missing .cmd file, \
244 - due to $(notdir $@) not in $$(targets) \
245 ) \
246 ) \
247 ) \
248 ), \
249 - due to target missing \
250 ) \
251 )
252
253 why = $(space)$(strip $(_why))
254 endif
255
256 ###############################################################################
257
258 # delete partially updated (i.e. corrupted) files on error
259 .DELETE_ON_ERROR:
260
261 # do not delete intermediate files automatically
262 #
263 # .NOTINTERMEDIATE is more correct, but only available on newer Make versions.
264 # Make 4.4 introduced .NOTINTERMEDIATE, and it appears in .FEATURES, but the
265 # global .NOTINTERMEDIATE does not work. We can use it on Make > 4.4.
266 # Use .SECONDARY for older Make versions, but "newer-prereq" cannot detect
267 # deleted files.
268 ifneq ($(and $(filter notintermediate, $(.FEATURES)),$(filter-out 4.4,$(MAKE_VERSION))),)
269 .NOTINTERMEDIATE:
270 else
271 .SECONDARY:
272 endif
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