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