xref: /openbmc/linux/scripts/Kbuild.include (revision 75016ca3) 
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