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Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +00001####
2# kbuild: Generic definitions
3
Roman Zippelbeda9f32007-02-08 22:48:51 +01004# Convenient variables
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +00005comma := ,
Masahiro Yamada13338932014-03-20 11:08:20 +09006quote := "
Sam Ravnborgd51bfb72006-01-06 22:35:59 +01007squote := '
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +00008empty :=
9space := $(empty) $(empty)
Masahiro Yamada9c8fa9b2016-05-07 15:48:26 +090010space_escape := _-_SPACE_-_
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +000011
12###
Sam Ravnborg48f1f052006-07-23 19:37:44 +020013# Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
14dot-target = $(dir $@).$(notdir $@)
15
16###
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +000017# The temporary file to save gcc -MD generated dependencies must not
18# contain a comma
Sam Ravnborg48f1f052006-07-23 19:37:44 +020019depfile = $(subst $(comma),_,$(dot-target).d)
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +000020
21###
Sam Ravnborg5e8d7802006-07-01 09:58:02 +020022# filename of target with directory and extension stripped
23basetarget = $(basename $(notdir $@))
24
25###
Arnaud Lacombee0318d82011-06-01 17:50:25 -040026# filename of first prerequisite with directory and extension stripped
27baseprereq = $(basename $(notdir $<))
28
29###
Sam Ravnborgd51bfb72006-01-06 22:35:59 +010030# Escape single quote for use in echo statements
31escsq = $(subst $(squote),'\$(squote)',$1)
32
33###
Mike Frysinger5410ecc2008-11-06 03:31:34 -050034# Easy method for doing a status message
35 kecho := :
36 quiet_kecho := echo
37silent_kecho := :
38kecho := $($(quiet)kecho)
39
40###
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +000041# filechk is used to check if the content of a generated file is updated.
42# Sample usage:
43# define filechk_sample
44# echo $KERNELRELEASE
45# endef
46# version.h : Makefile
47# $(call filechk,sample)
48# The rule defined shall write to stdout the content of the new file.
49# The existing file will be compared with the new one.
50# - If no file exist it is created
51# - If the content differ the new file is used
52# - If they are equal no change, and no timestamp update
53# - stdin is piped in from the first prerequisite ($<) so one has
54# to specify a valid file as first prerequisite (often the kbuild file)
55define filechk
56 $(Q)set -e; \
Mike Frysingerfd54f502008-11-06 03:31:35 -050057 $(kecho) ' CHK $@'; \
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +000058 mkdir -p $(dir $@); \
59 $(filechk_$(1)) < $< > $@.tmp; \
60 if [ -r $@ ] && cmp -s $@ $@.tmp; then \
61 rm -f $@.tmp; \
62 else \
Mike Frysingerfd54f502008-11-06 03:31:35 -050063 $(kecho) ' UPD $@'; \
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +000064 mv -f $@.tmp $@; \
65 fi
66endef
67
Sam Ravnborg20a468b2006-01-22 13:34:15 +010068######
Sam Ravnborg9d6e7a72006-02-18 10:03:40 +010069# gcc support functions
Sam Ravnborg20a468b2006-01-22 13:34:15 +010070# See documentation in Documentation/kbuild/makefiles.txt
71
Sam Ravnborg910b4042007-10-19 21:46:01 +020072# cc-cross-prefix
73# Usage: CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu- m68k-linux-)
74# Return first prefix where a prefix$(CC) is found in PATH.
75# If no $(CC) found in PATH with listed prefixes return nothing
76cc-cross-prefix = \
77 $(word 1, $(foreach c,$(1), \
78 $(shell set -e; \
79 if (which $(strip $(c))$(CC)) > /dev/null 2>&1 ; then \
80 echo $(c); \
81 fi)))
82
Roman Zippelbeda9f32007-02-08 22:48:51 +010083# output directory for tests below
84TMPOUT := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/)
85
86# try-run
87# Usage: option = $(call try-run, $(CC)...-o "$$TMP",option-ok,otherwise)
88# Exit code chooses option. "$$TMP" is can be used as temporary file and
89# is automatically cleaned up.
90try-run = $(shell set -e; \
91 TMP="$(TMPOUT).$$$$.tmp"; \
Sam Ravnborg691ef3e2009-09-19 10:31:45 +020092 TMPO="$(TMPOUT).$$$$.o"; \
Roman Zippelbeda9f32007-02-08 22:48:51 +010093 if ($(1)) >/dev/null 2>&1; \
94 then echo "$(2)"; \
95 else echo "$(3)"; \
96 fi; \
Sam Ravnborg691ef3e2009-09-19 10:31:45 +020097 rm -f "$$TMP" "$$TMPO")
Roman Zippel347a00f2006-12-10 02:18:41 -080098
Sam Ravnborg20a468b2006-01-22 13:34:15 +010099# as-option
Oleg Verychbff288c2007-02-07 23:04:35 +0100100# Usage: cflags-y += $(call as-option,-Wa$(comma)-isa=foo,)
Roman Zippelbeda9f32007-02-08 22:48:51 +0100101
102as-option = $(call try-run,\
Jean Delvareb1e0d8b2012-10-02 16:42:36 +0200103 $(CC) $(KBUILD_CFLAGS) $(1) -c -x assembler /dev/null -o "$$TMP",$(1),$(2))
Sam Ravnborg20a468b2006-01-22 13:34:15 +0100104
Andi Kleene2414912006-09-26 10:52:30 +0200105# as-instr
Oleg Verychbff288c2007-02-07 23:04:35 +0100106# Usage: cflags-y += $(call as-instr,instr,option1,option2)
Roman Zippelbeda9f32007-02-08 22:48:51 +0100107
108as-instr = $(call try-run,\
Jean Delvareb1e0d8b2012-10-02 16:42:36 +0200109 printf "%b\n" "$(1)" | $(CC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" -,$(2),$(3))
Andi Kleene2414912006-09-26 10:52:30 +0200110
Emese Revfyd26e9412016-06-17 23:28:34 -0700111# Do not attempt to build with gcc plugins during cc-option tests.
112# (And this uses delayed resolution so the flags will be up to date.)
113CC_OPTION_CFLAGS = $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS))
114
Sam Ravnborg20a468b2006-01-22 13:34:15 +0100115# cc-option
Oleg Verychbff288c2007-02-07 23:04:35 +0100116# Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
Roman Zippelbeda9f32007-02-08 22:48:51 +0100117
118cc-option = $(call try-run,\
Emese Revfyd26e9412016-06-17 23:28:34 -0700119 $(CC) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",$(1),$(2))
Sam Ravnborg20a468b2006-01-22 13:34:15 +0100120
121# cc-option-yn
Oleg Verychbff288c2007-02-07 23:04:35 +0100122# Usage: flag := $(call cc-option-yn,-march=winchip-c6)
Roman Zippelbeda9f32007-02-08 22:48:51 +0100123cc-option-yn = $(call try-run,\
Emese Revfyd26e9412016-06-17 23:28:34 -0700124 $(CC) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
Sam Ravnborg20a468b2006-01-22 13:34:15 +0100125
126# cc-option-align
127# Prefix align with either -falign or -malign
128cc-option-align = $(subst -functions=0,,\
Roman Zippelbeda9f32007-02-08 22:48:51 +0100129 $(call cc-option,-falign-functions=0,-malign-functions=0))
Sam Ravnborg20a468b2006-01-22 13:34:15 +0100130
Michal Marek8417da6f2011-05-02 12:51:15 +0200131# cc-disable-warning
132# Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable)
133cc-disable-warning = $(call try-run,\
Emese Revfyd26e9412016-06-17 23:28:34 -0700134 $(CC) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
Michal Marek8417da6f2011-05-02 12:51:15 +0200135
Michal Marek5631d9c2015-08-19 17:36:41 +0200136# cc-name
137# Expands to either gcc or clang
138cc-name = $(shell $(CC) -v 2>&1 | grep -q "clang version" && echo clang || echo gcc)
139
Sam Ravnborg20a468b2006-01-22 13:34:15 +0100140# cc-version
Sam Ravnborg8eb3afe2006-07-23 19:49:45 +0200141cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC))
Sam Ravnborg20a468b2006-01-22 13:34:15 +0100142
Segher Boessenkool0ab2a272007-05-19 18:49:07 +0200143# cc-fullversion
Segher Boessenkool0ab2a272007-05-19 18:49:07 +0200144cc-fullversion = $(shell $(CONFIG_SHELL) \
145 $(srctree)/scripts/gcc-version.sh -p $(CC))
146
Sam Ravnborg20a468b2006-01-22 13:34:15 +0100147# cc-ifversion
148# Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
Masahiro Yamada6dcb4e52014-12-25 14:31:27 +0900149cc-ifversion = $(shell [ $(cc-version) $(1) $(2) ] && echo $(3) || echo $(4))
Sam Ravnborg20a468b2006-01-22 13:34:15 +0100150
Sam Ravnborgf86fd302009-09-19 10:14:33 +0200151# cc-ldoption
152# Usage: ldflags += $(call cc-ldoption, -Wl$(comma)--hash-style=both)
153cc-ldoption = $(call try-run,\
Jean Delvareb1e0d8b2012-10-02 16:42:36 +0200154 $(CC) $(1) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
Roland McGrath0b0bf7a2006-07-30 03:04:06 -0700155
Sam Ravnborg691ef3e2009-09-19 10:31:45 +0200156# ld-option
157# Usage: LDFLAGS += $(call ld-option, -X)
158ld-option = $(call try-run,\
Antony Pavlov5b83df22013-04-03 18:42:33 +0400159 $(CC) -x c /dev/null -c -o "$$TMPO" ; $(LD) $(1) "$$TMPO" -o "$$TMP",$(1),$(2))
Sam Ravnborg691ef3e2009-09-19 10:31:45 +0200160
Michal Marek40df7592011-04-20 13:45:30 +0200161# ar-option
162# Usage: KBUILD_ARFLAGS := $(call ar-option,D)
163# Important: no spaces around options
164ar-option = $(call try-run, $(AR) rc$(1) "$$TMP",$(1),$(2))
165
Andi Kleenccbef162014-02-08 09:01:13 +0100166# ld-version
Andi Kleenccbef162014-02-08 09:01:13 +0100167# Note this is mainly for HJ Lu's 3 number binutil versions
168ld-version = $(shell $(LD) --version | $(srctree)/scripts/ld-version.sh)
169
170# ld-ifversion
171# Usage: $(call ld-ifversion, -ge, 22252, y)
Masahiro Yamada6dcb4e52014-12-25 14:31:27 +0900172ld-ifversion = $(shell [ $(ld-version) $(1) $(2) ] && echo $(3) || echo $(4))
Andi Kleenccbef162014-02-08 09:01:13 +0100173
Oleg Verych5de043f2007-02-06 02:18:21 +0100174######
175
Roman Zippelbeda9f32007-02-08 22:48:51 +0100176###
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +0000177# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
178# Usage:
179# $(Q)$(MAKE) $(build)=dir
Masahiro Yamada5b2389b2014-09-09 20:03:58 +0900180build := -f $(srctree)/scripts/Makefile.build obj
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +0000181
Michal Marekbc081dd2009-12-07 16:38:33 +0100182###
183# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.modbuiltin obj=
184# Usage:
185# $(Q)$(MAKE) $(modbuiltin)=dir
Masahiro Yamada5b2389b2014-09-09 20:03:58 +0900186modbuiltin := -f $(srctree)/scripts/Makefile.modbuiltin obj
Michal Marekbc081dd2009-12-07 16:38:33 +0100187
Robert Richter9fb5e532014-09-03 15:29:24 +0200188###
189# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.dtbinst obj=
190# Usage:
191# $(Q)$(MAKE) $(dtbinst)=dir
192dtbinst := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.dtbinst obj
193
Linus Torvaldsd08372c2014-12-20 13:31:14 -0800194###
Masahiro Yamada371fdc72014-11-26 19:31:13 +0900195# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.clean obj=
196# Usage:
197# $(Q)$(MAKE) $(clean)=dir
198clean := -f $(srctree)/scripts/Makefile.clean obj
199
200###
Masahiro Yamada1846dfb2014-12-02 13:30:46 +0900201# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.headersinst obj=
Masahiro Yamada371fdc72014-11-26 19:31:13 +0900202# Usage:
203# $(Q)$(MAKE) $(hdr-inst)=dir
Masahiro Yamada1846dfb2014-12-02 13:30:46 +0900204hdr-inst := -f $(srctree)/scripts/Makefile.headersinst obj
Masahiro Yamada371fdc72014-11-26 19:31:13 +0900205
Roman Zippelbeda9f32007-02-08 22:48:51 +0100206# Prefix -I with $(srctree) if it is not an absolute path.
Sam Ravnborg5b91c332008-12-03 21:22:21 +0100207# skip if -I has no parameter
208addtree = $(if $(patsubst -I%,%,$(1)), \
Arnd Bergmanndb547ef2016-06-15 17:45:47 +0200209$(if $(filter-out -I/% -I./% -I../%,$(1)),$(patsubst -I%,-I$(srctree)/%,$(1)),$(1)))
Sam Ravnborgd9df92e2006-04-07 08:36:49 +0200210
Oleg Verych5de043f2007-02-06 02:18:21 +0100211# Find all -I options and call addtree
Roman Zippelbeda9f32007-02-08 22:48:51 +0100212flags = $(foreach o,$($(1)),$(if $(filter -I%,$(o)),$(call addtree,$(o)),$(o)))
Oleg Verych5de043f2007-02-06 02:18:21 +0100213
214# echo command.
215# Short version is used, if $(quiet) equals `quiet_', otherwise full one.
Oleg Verychbff288c2007-02-07 23:04:35 +0100216echo-cmd = $(if $($(quiet)cmd_$(1)),\
Oleg Verych5de043f2007-02-06 02:18:21 +0100217 echo ' $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
218
219# printing commands
Jan Beulich6176aa92006-01-30 10:04:27 +0100220cmd = @$(echo-cmd) $(cmd_$(1))
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +0000221
Oleg Verych5de043f2007-02-06 02:18:21 +0100222# Add $(obj)/ for paths that are not absolute
Oleg Verychbff288c2007-02-07 23:04:35 +0100223objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o)))
Sam Ravnborg0a504f22005-09-10 21:02:11 +0200224
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +0000225###
Oleg Verych5de043f2007-02-06 02:18:21 +0100226# if_changed - execute command if any prerequisite is newer than
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +0000227# target, or command line has changed
228# if_changed_dep - as if_changed, but uses fixdep to reveal dependencies
229# including used config symbols
230# if_changed_rule - as if_changed but execute rule instead
231# See Documentation/kbuild/makefiles.txt for more info
232
233ifneq ($(KBUILD_NOCMDDEP),1)
Masahiro Yamada9c8fa9b2016-05-07 15:48:26 +0900234# Check if both arguments are the same including their order. Result is empty
235# string if equal. User may override this check using make KBUILD_NOCMDDEP=1
236arg-check = $(filter-out $(subst $(space),$(space_escape),$(strip $(cmd_$@))), \
237 $(subst $(space),$(space_escape),$(strip $(cmd_$1))))
Michal Marekc4d5ee12011-05-16 16:37:34 +0200238else
239arg-check = $(if $(strip $(cmd_$@)),,1)
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +0000240endif
241
Michal Marek164f0d22014-08-07 21:39:57 +0200242# Replace >$< with >$$< to preserve $ when reloading the .cmd file
243# (needed for make)
244# Replace >#< with >\#< to avoid starting a comment in the .cmd file
245# (needed for make)
246# Replace >'< with >'\''< to be able to enclose the whole string in '...'
247# (needed for the shell)
248make-cmd = $(call escsq,$(subst \#,\\\#,$(subst $$,$$$$,$(cmd_$(1)))))
Jan Beulich6176aa92006-01-30 10:04:27 +0100249
Sam Ravnborg48f1f052006-07-23 19:37:44 +0200250# Find any prerequisites that is newer than target or that does not exist.
251# PHONY targets skipped in both cases.
252any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^)
253
Oleg Verych5de043f2007-02-06 02:18:21 +0100254# Execute command if command has changed or prerequisite(s) are updated.
Paul Smith4f193362006-03-05 17:14:10 -0500255#
Sam Ravnborg48f1f052006-07-23 19:37:44 +0200256if_changed = $(if $(strip $(any-prereq) $(arg-check)), \
257 @set -e; \
258 $(echo-cmd) $(cmd_$(1)); \
Masahiro Yamada2aedcd02016-03-03 17:36:30 +0900259 printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +0000260
Oleg Verych5de043f2007-02-06 02:18:21 +0100261# Execute the command and also postprocess generated .d dependencies file.
Sam Ravnborg48f1f052006-07-23 19:37:44 +0200262if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ), \
263 @set -e; \
Nicolas Pitree4aca452016-02-17 15:50:06 -0500264 $(cmd_and_fixdep), @:)
265
Nicolas Pitrec1a95fd2016-01-22 13:41:57 -0500266ifndef CONFIG_TRIM_UNUSED_KSYMS
267
Nicolas Pitree4aca452016-02-17 15:50:06 -0500268cmd_and_fixdep = \
Sam Ravnborg48f1f052006-07-23 19:37:44 +0200269 $(echo-cmd) $(cmd_$(1)); \
270 scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
271 rm -f $(depfile); \
Nicolas Pitree4aca452016-02-17 15:50:06 -0500272 mv -f $(dot-target).tmp $(dot-target).cmd;
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +0000273
Nicolas Pitrec1a95fd2016-01-22 13:41:57 -0500274else
275
276# Filter out exported kernel symbol names from the preprocessor output.
277# See also __KSYM_DEPS__ in include/linux/export.h.
278# We disable the depfile generation here, so as not to overwrite the existing
279# depfile while fixdep is parsing it.
280flags_nodeps = $(filter-out -Wp$(comma)-M%, $($(1)))
281ksym_dep_filter = \
282 case "$(1)" in \
Nicolas Pitre366f4852016-04-26 11:21:34 -0400283 cc_*_c|cpp_i_c) \
284 $(CPP) $(call flags_nodeps,c_flags) -D__KSYM_DEPS__ $< ;; \
285 as_*_S|cpp_s_S) \
286 $(CPP) $(call flags_nodeps,a_flags) -D__KSYM_DEPS__ $< ;; \
Marcin Nowakowski0d070d22017-02-13 11:15:56 +0100287 boot*|build*|cpp_its_S|*cpp_lds_S|dtc|host*|vdso*) : ;; \
Nicolas Pitre366f4852016-04-26 11:21:34 -0400288 *) echo "Don't know how to preprocess $(1)" >&2; false ;; \
Nicolas Pitref110e0f2016-04-28 17:29:42 -0400289 esac | tr ";" "\n" | sed -rn 's/^.*=== __KSYM_(.*) ===.*$$/KSYM_\1/p'
Nicolas Pitrec1a95fd2016-01-22 13:41:57 -0500290
291cmd_and_fixdep = \
292 $(echo-cmd) $(cmd_$(1)); \
293 $(ksym_dep_filter) | \
294 scripts/basic/fixdep -e $(depfile) $@ '$(make-cmd)' \
295 > $(dot-target).tmp; \
296 rm -f $(depfile); \
297 mv -f $(dot-target).tmp $(dot-target).cmd;
298
299endif
300
Sam Ravnborg8ec4b4f2005-07-25 20:10:36 +0000301# Usage: $(call if_changed_rule,foo)
Roman Zippelbeda9f32007-02-08 22:48:51 +0100302# Will check if $(cmd_foo) or any of the prerequisites changed,
303# and if so will execute $(rule_foo).
Sam Ravnborg48f1f052006-07-23 19:37:44 +0200304if_changed_rule = $(if $(strip $(any-prereq) $(arg-check) ), \
305 @set -e; \
Masahiro Yamada2aedcd02016-03-03 17:36:30 +0900306 $(rule_$(1)), @:)
Sam Ravnborg48f1f052006-07-23 19:37:44 +0200307
Sam Ravnborg45d506b2006-08-08 21:35:14 +0200308###
309# why - tell why a a target got build
310# enabled by make V=2
311# Output (listed in the order they are checked):
312# (1) - due to target is PHONY
313# (2) - due to target missing
314# (3) - due to: file1.h file2.h
315# (4) - due to command line change
316# (5) - due to missing .cmd file
317# (6) - due to target not in $(targets)
318# (1) PHONY targets are always build
319# (2) No target, so we better build it
320# (3) Prerequisite is newer than target
321# (4) The command line stored in the file named dir/.target.cmd
322# differed from actual command line. This happens when compiler
323# options changes
324# (5) No dir/.target.cmd file (used to store command line)
325# (6) No dir/.target.cmd file and target not listed in $(targets)
326# This is a good hint that there is a bug in the kbuild file
327ifeq ($(KBUILD_VERBOSE),2)
328why = \
329 $(if $(filter $@, $(PHONY)),- due to target is PHONY, \
330 $(if $(wildcard $@), \
331 $(if $(strip $(any-prereq)),- due to: $(any-prereq), \
332 $(if $(arg-check), \
333 $(if $(cmd_$@),- due to command line change, \
334 $(if $(filter $@, $(targets)), \
335 - due to missing .cmd file, \
336 - due to $(notdir $@) not in $$(targets) \
337 ) \
338 ) \
339 ) \
340 ), \
341 - due to target missing \
342 ) \
343 )
344
345echo-why = $(call escsq, $(strip $(why)))
346endif
David Woodhouse3ee550f2015-08-14 16:17:16 +0100347
348###############################################################################
349#
350# When a Kconfig string contains a filename, it is suitable for
351# passing to shell commands. It is surrounded by double-quotes, and
352# any double-quotes or backslashes within it are escaped by
353# backslashes.
354#
355# This is no use for dependencies or $(wildcard). We need to strip the
356# surrounding quotes and the escaping from quotes and backslashes, and
357# we *do* need to escape any spaces in the string. So, for example:
358#
359# Usage: $(eval $(call config_filename,FOO))
360#
361# Defines FOO_FILENAME based on the contents of the CONFIG_FOO option,
362# transformed as described above to be suitable for use within the
363# makefile.
364#
365# Also, if the filename is a relative filename and exists in the source
366# tree but not the build tree, define FOO_SRCPREFIX as $(srctree)/ to
367# be prefixed to *both* command invocation and dependencies.
368#
369# Note: We also print the filenames in the quiet_cmd_foo text, and
370# perhaps ought to have a version specially escaped for that purpose.
371# But it's only cosmetic, and $(patsubst "%",%,$(CONFIG_FOO)) is good
372# enough. It'll strip the quotes in the common case where there's no
373# space and it's a simple filename, and it'll retain the quotes when
374# there's a space. There are some esoteric cases in which it'll print
375# the wrong thing, but we don't really care. The actual dependencies
376# and commands *do* get it right, with various combinations of single
377# and double quotes, backslashes and spaces in the filenames.
378#
379###############################################################################
380#
David Woodhouse3ee550f2015-08-14 16:17:16 +0100381define config_filename
382ifneq ($$(CONFIG_$(1)),"")
383$(1)_FILENAME := $$(subst \\,\,$$(subst \$$(quote),$$(quote),$$(subst $$(space_escape),\$$(space),$$(patsubst "%",%,$$(subst $$(space),$$(space_escape),$$(CONFIG_$(1)))))))
384ifneq ($$(patsubst /%,%,$$(firstword $$($(1)_FILENAME))),$$(firstword $$($(1)_FILENAME)))
385else
386ifeq ($$(wildcard $$($(1)_FILENAME)),)
387ifneq ($$(wildcard $$(srctree)/$$($(1)_FILENAME)),)
388$(1)_SRCPREFIX := $(srctree)/
389endif
390endif
391endif
392endif
393endef
394#
395###############################################################################