xref: /linux-6.15/scripts/Kbuild.include (revision c25e1c55) 
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),                                        \
146	$(cmd);                                                              \
147	printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
148
149# Execute the command and also postprocess generated .d dependencies file.
150if_changed_dep = $(if $(if-changed-cond),$(cmd_and_fixdep),@:)
151
152cmd_and_fixdep =                                                             \
153	$(cmd);                                                              \
154	scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).cmd;\
155	rm -f $(depfile)
156
157# Usage: $(call if_changed_rule,foo)
158# Will check if $(cmd_foo) or any of the prerequisites changed,
159# and if so will execute $(rule_foo).
160if_changed_rule = $(if $(if-changed-cond),$(rule_$(1)),@:)
161
162###
163# why - tell why a target got built
164#       enabled by make V=2
165#       Output (listed in the order they are checked):
166#          (1) - due to target is PHONY
167#          (2) - due to target missing
168#          (3) - due to: file1.h file2.h
169#          (4) - due to command line change
170#          (5) - due to missing .cmd file
171#          (6) - due to target not in $(targets)
172# (1) PHONY targets are always build
173# (2) No target, so we better build it
174# (3) Prerequisite is newer than target
175# (4) The command line stored in the file named dir/.target.cmd
176#     differed from actual command line. This happens when compiler
177#     options changes
178# (5) No dir/.target.cmd file (used to store command line)
179# (6) No dir/.target.cmd file and target not listed in $(targets)
180#     This is a good hint that there is a bug in the kbuild file
181ifeq ($(KBUILD_VERBOSE),2)
182why =                                                                        \
183    $(if $(filter $@, $(PHONY)),- due to target is PHONY,                    \
184        $(if $(wildcard $@),                                                 \
185            $(if $(newer-prereqs),- due to: $(newer-prereqs),                \
186                $(if $(cmd-check),                                           \
187                    $(if $(cmd_$@),- due to command line change,             \
188                        $(if $(filter $@, $(targets)),                       \
189                            - due to missing .cmd file,                      \
190                            - due to $(notdir $@) not in $$(targets)         \
191                         )                                                   \
192                     )                                                       \
193                 )                                                           \
194             ),                                                              \
195             - due to target missing                                         \
196         )                                                                   \
197     )
198
199echo-why = $(call escsq, $(strip $(why)))
200endif
201
202###############################################################################
203
204# delete partially updated (i.e. corrupted) files on error
205.DELETE_ON_ERROR:
206
207# do not delete intermediate files automatically
208.SECONDARY:
209