Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
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linux
1####
2# kbuild: Generic definitions
3
4# Convinient variables
5comma := ,
6squote := '
7empty :=
8space := $(empty) $(empty)
9
10###
11# Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
12dot-target = $(dir $@).$(notdir $@)
13
14###
15# The temporary file to save gcc -MD generated dependencies must not
16# contain a comma
17depfile = $(subst $(comma),_,$(dot-target).d)
18
19###
20# filename of target with directory and extension stripped
21basetarget = $(basename $(notdir $@))
22
23###
24# Escape single quote for use in echo statements
25escsq = $(subst $(squote),'\$(squote)',$1)
26
27###
28# filechk is used to check if the content of a generated file is updated.
29# Sample usage:
30# define filechk_sample
31# echo $KERNELRELEASE
32# endef
33# version.h : Makefile
34# $(call filechk,sample)
35# The rule defined shall write to stdout the content of the new file.
36# The existing file will be compared with the new one.
37# - If no file exist it is created
38# - If the content differ the new file is used
39# - If they are equal no change, and no timestamp update
40# - stdin is piped in from the first prerequisite ($<) so one has
41# to specify a valid file as first prerequisite (often the kbuild file)
42define filechk
43 $(Q)set -e; \
44 echo ' CHK $@'; \
45 mkdir -p $(dir $@); \
46 $(filechk_$(1)) < $< > $@.tmp; \
47 if [ -r $@ ] && cmp -s $@ $@.tmp; then \
48 rm -f $@.tmp; \
49 else \
50 echo ' UPD $@'; \
51 mv -f $@.tmp $@; \
52 fi
53endef
54
55######
56# gcc support functions
57# See documentation in Documentation/kbuild/makefiles.txt
58
59# as-option
60# Usage: cflags-y += $(call as-option, -Wa$(comma)-isa=foo,)
61
62as-option = $(shell if $(CC) $(CFLAGS) $(1) -Wa,-Z -c -o /dev/null \
63 -xassembler /dev/null > /dev/null 2>&1; then echo "$(1)"; \
64 else echo "$(2)"; fi ;)
65
66# as-instr
67# Usage: cflags-y += $(call as-instr, instr, option1, option2)
68
69as-instr = $(shell if echo -e "$(1)" | $(AS) >/dev/null 2>&1 -W -Z -o astest$$$$.out ; \
70 then echo "$(2)"; else echo "$(3)"; fi; \
71 rm -f astest$$$$.out)
72
73# cc-option
74# Usage: cflags-y += $(call cc-option, -march=winchip-c6, -march=i586)
75
76cc-option = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
77 > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)
78
79# cc-option-yn
80# Usage: flag := $(call cc-option-yn, -march=winchip-c6)
81cc-option-yn = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
82 > /dev/null 2>&1; then echo "y"; else echo "n"; fi;)
83
84# cc-option-align
85# Prefix align with either -falign or -malign
86cc-option-align = $(subst -functions=0,,\
87 $(call cc-option,-falign-functions=0,-malign-functions=0))
88
89# cc-version
90# Usage gcc-ver := $(call cc-version, $(CC))
91cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC))
92
93# cc-ifversion
94# Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
95cc-ifversion = $(shell if [ $(call cc-version, $(CC)) $(1) $(2) ]; then \
96 echo $(3); fi;)
97
98# ld-option
99# Usage: ldflags += $(call ld-option, -Wl$(comma)--hash-style=both)
100ld-option = $(shell if $(CC) $(1) \
101 -nostdlib -o ldtest$$$$.out -xc /dev/null \
102 > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi; \
103 rm -f ldtest$$$$.out)
104
105###
106# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
107# Usage:
108# $(Q)$(MAKE) $(build)=dir
109build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj
110
111# Prefix -I with $(srctree) if it is not an absolute path
112addtree = $(if $(filter-out -I/%,$(1)),$(patsubst -I%,-I$(srctree)/%,$(1))) $(1)
113# Find all -I options and call addtree
114flags = $(foreach o,$($(1)),$(if $(filter -I%,$(o)),$(call addtree,$(o)),$(o)))
115
116# If quiet is set, only print short version of command
117cmd = @$(echo-cmd) $(cmd_$(1))
118
119# Add $(obj)/ for paths that is not absolute
120objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o)))
121
122###
123# if_changed - execute command if any prerequisite is newer than
124# target, or command line has changed
125# if_changed_dep - as if_changed, but uses fixdep to reveal dependencies
126# including used config symbols
127# if_changed_rule - as if_changed but execute rule instead
128# See Documentation/kbuild/makefiles.txt for more info
129
130ifneq ($(KBUILD_NOCMDDEP),1)
131# Check if both arguments has same arguments. Result in empty string if equal
132# User may override this check using make KBUILD_NOCMDDEP=1
133arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \
134 $(filter-out $(cmd_$@), $(cmd_$(1))) )
135endif
136
137# echo command. Short version is $(quiet) equals quiet, otherwise full command
138echo-cmd = $(if $($(quiet)cmd_$(1)), \
139 echo ' $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
140
141# >'< substitution is for echo to work,
142# >$< substitution to preserve $ when reloading .cmd file
143# note: when using inline perl scripts [perl -e '...$$t=1;...']
144# in $(cmd_xxx) double $$ your perl vars
145make-cmd = $(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1)))))
146
147# Find any prerequisites that is newer than target or that does not exist.
148# PHONY targets skipped in both cases.
149any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^)
150
151# Execute command if command has changed or prerequisitei(s) are updated
152#
153if_changed = $(if $(strip $(any-prereq) $(arg-check)), \
154 @set -e; \
155 $(echo-cmd) $(cmd_$(1)); \
156 echo 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd)
157
158# execute the command and also postprocess generated .d dependencies
159# file
160if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ), \
161 @set -e; \
162 $(echo-cmd) $(cmd_$(1)); \
163 scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
164 rm -f $(depfile); \
165 mv -f $(dot-target).tmp $(dot-target).cmd)
166
167# Usage: $(call if_changed_rule,foo)
168# will check if $(cmd_foo) changed, or any of the prequisites changed,
169# and if so will execute $(rule_foo)
170if_changed_rule = $(if $(strip $(any-prereq) $(arg-check) ), \
171 @set -e; \
172 $(rule_$(1)))
173
174###
175# why - tell why a a target got build
176# enabled by make V=2
177# Output (listed in the order they are checked):
178# (1) - due to target is PHONY
179# (2) - due to target missing
180# (3) - due to: file1.h file2.h
181# (4) - due to command line change
182# (5) - due to missing .cmd file
183# (6) - due to target not in $(targets)
184# (1) PHONY targets are always build
185# (2) No target, so we better build it
186# (3) Prerequisite is newer than target
187# (4) The command line stored in the file named dir/.target.cmd
188# differed from actual command line. This happens when compiler
189# options changes
190# (5) No dir/.target.cmd file (used to store command line)
191# (6) No dir/.target.cmd file and target not listed in $(targets)
192# This is a good hint that there is a bug in the kbuild file
193ifeq ($(KBUILD_VERBOSE),2)
194why = \
195 $(if $(filter $@, $(PHONY)),- due to target is PHONY, \
196 $(if $(wildcard $@), \
197 $(if $(strip $(any-prereq)),- due to: $(any-prereq), \
198 $(if $(arg-check), \
199 $(if $(cmd_$@),- due to command line change, \
200 $(if $(filter $@, $(targets)), \
201 - due to missing .cmd file, \
202 - due to $(notdir $@) not in $$(targets) \
203 ) \
204 ) \
205 ) \
206 ), \
207 - due to target missing \
208 ) \
209 )
210
211echo-why = $(call escsq, $(strip $(why)))
212endif