xref: /linux-6.15/scripts/Makefile.build (revision e2a86a29)
1# SPDX-License-Identifier: GPL-2.0
2# ==========================================================================
3# Building
4# ==========================================================================
5
6src := $(obj)
7
8PHONY := __build
9__build:
10
11# Init all relevant variables used in kbuild files so
12# 1) they have correct type
13# 2) they do not inherit any value from the environment
14obj-y :=
15obj-m :=
16lib-y :=
17lib-m :=
18always-y :=
19always-m :=
20targets :=
21subdir-y :=
22subdir-m :=
23EXTRA_AFLAGS   :=
24EXTRA_CFLAGS   :=
25EXTRA_CPPFLAGS :=
26EXTRA_LDFLAGS  :=
27asflags-y  :=
28ccflags-y  :=
29cppflags-y :=
30ldflags-y  :=
31
32subdir-asflags-y :=
33subdir-ccflags-y :=
34
35# Read auto.conf if it exists, otherwise ignore
36-include include/config/auto.conf
37
38include $(srctree)/scripts/Kbuild.include
39include $(srctree)/scripts/Makefile.compiler
40
41# The filename Kbuild has precedence over Makefile
42kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
43kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
44include $(kbuild-file)
45
46include $(srctree)/scripts/Makefile.lib
47
48# Do not include hostprogs rules unless needed.
49# $(sort ...) is used here to remove duplicated words and excessive spaces.
50hostprogs := $(sort $(hostprogs))
51ifneq ($(hostprogs),)
52include $(srctree)/scripts/Makefile.host
53endif
54
55# Do not include userprogs rules unless needed.
56# $(sort ...) is used here to remove duplicated words and excessive spaces.
57userprogs := $(sort $(userprogs))
58ifneq ($(userprogs),)
59include $(srctree)/scripts/Makefile.userprogs
60endif
61
62ifndef obj
63$(warning kbuild: Makefile.build is included improperly)
64endif
65
66ifeq ($(need-modorder),)
67ifneq ($(obj-m),)
68$(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.)
69$(warning You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.)
70endif
71endif
72
73# ===========================================================================
74
75# subdir-builtin and subdir-modorder may contain duplications. Use $(sort ...)
76subdir-builtin := $(sort $(filter %/built-in.a, $(real-obj-y)))
77subdir-modorder := $(sort $(filter %/modules.order, $(obj-m)))
78
79targets-for-builtin := $(extra-y)
80
81ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
82targets-for-builtin += $(obj)/lib.a
83endif
84
85ifdef need-builtin
86targets-for-builtin += $(obj)/built-in.a
87endif
88
89targets-for-modules := $(patsubst %.o, %.mod, $(filter %.o, $(obj-m)))
90
91ifdef need-modorder
92targets-for-modules += $(obj)/modules.order
93endif
94
95targets += $(targets-for-builtin) $(targets-for-modules)
96
97# Linus' kernel sanity checking tool
98ifeq ($(KBUILD_CHECKSRC),1)
99  quiet_cmd_checksrc       = CHECK   $<
100        cmd_checksrc       = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
101else ifeq ($(KBUILD_CHECKSRC),2)
102  quiet_cmd_force_checksrc = CHECK   $<
103        cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
104endif
105
106ifneq ($(KBUILD_EXTRA_WARN),)
107  cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $<
108endif
109
110# Compile C sources (.c)
111# ---------------------------------------------------------------------------
112
113quiet_cmd_cc_s_c = CC $(quiet_modtag)  $@
114      cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS) $(CC_FLAGS_LTO), $(c_flags)) -fverbose-asm -S -o $@ $<
115
116$(obj)/%.s: $(src)/%.c FORCE
117	$(call if_changed_dep,cc_s_c)
118
119quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
120cmd_cpp_i_c       = $(CPP) $(c_flags) -o $@ $<
121
122$(obj)/%.i: $(src)/%.c FORCE
123	$(call if_changed_dep,cpp_i_c)
124
125# These mirror gensymtypes_S and co below, keep them in synch.
126cmd_gensymtypes_c =                                                         \
127    $(CPP) -D__GENKSYMS__ $(c_flags) $< |                                   \
128    scripts/genksyms/genksyms $(if $(1), -T $(2))                           \
129     $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS))                             \
130     $(if $(KBUILD_PRESERVE),-p)                                            \
131     -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
132
133quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
134cmd_cc_symtypes_c =                                                         \
135    $(call cmd_gensymtypes_c,true,$@) >/dev/null;                           \
136    test -s $@ || rm -f $@
137
138$(obj)/%.symtypes : $(src)/%.c FORCE
139	$(call cmd,cc_symtypes_c)
140
141# LLVM assembly
142# Generate .ll files from .c
143quiet_cmd_cc_ll_c = CC $(quiet_modtag)  $@
144      cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $<
145
146$(obj)/%.ll: $(src)/%.c FORCE
147	$(call if_changed_dep,cc_ll_c)
148
149# C (.c) files
150# The C file is compiled and updated dependency information is generated.
151# (See cmd_cc_o_c + relevant part of rule_cc_o_c)
152
153quiet_cmd_cc_o_c = CC $(quiet_modtag)  $@
154      cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
155
156ifdef CONFIG_MODVERSIONS
157# When module versioning is enabled the following steps are executed:
158# o compile a <file>.o from <file>.c
159# o if <file>.o doesn't contain a __ksymtab version, i.e. does
160#   not export symbols, it's done.
161# o otherwise, we calculate symbol versions using the good old
162#   genksyms on the preprocessed source and postprocess them in a way
163#   that they are usable as a linker script
164# o generate .tmp_<file>.o from <file>.o using the linker to
165#   replace the unresolved symbols __crc_exported_symbol with
166#   the actual value of the checksum generated by genksyms
167# o remove .tmp_<file>.o to <file>.o
168
169ifdef CONFIG_LTO_CLANG
170# Generate .o.symversions files for each .o with exported symbols, and link these
171# to the kernel and/or modules at the end.
172cmd_modversions_c =								\
173	if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then			\
174		$(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
175		    > $@.symversions;						\
176	fi;
177else
178cmd_modversions_c =								\
179	if $(OBJDUMP) -h $@ | grep -q __ksymtab; then				\
180		$(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
181		    > $(@D)/.tmp_$(@F:.o=.ver);					\
182										\
183		$(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ 		\
184			-T $(@D)/.tmp_$(@F:.o=.ver);				\
185		mv -f $(@D)/.tmp_$(@F) $@;					\
186		rm -f $(@D)/.tmp_$(@F:.o=.ver);					\
187	fi
188endif
189endif
190
191ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
192# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
193ifdef BUILD_C_RECORDMCOUNT
194ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
195  RECORDMCOUNT_FLAGS = -w
196endif
197# Due to recursion, we must skip empty.o.
198# The empty.o file is created in the make process in order to determine
199# the target endianness and word size. It is made before all other C
200# files, including recordmcount.
201sub_cmd_record_mcount =					\
202	if [ $(@) != "scripts/mod/empty.o" ]; then	\
203		$(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)";	\
204	fi;
205recordmcount_source := $(srctree)/scripts/recordmcount.c \
206		    $(srctree)/scripts/recordmcount.h
207else
208sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
209	"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
210	"$(if $(CONFIG_64BIT),64,32)" \
211	"$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
212	"$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
213	"$(if $(part-of-module),1,0)" "$(@)";
214recordmcount_source := $(srctree)/scripts/recordmcount.pl
215endif # BUILD_C_RECORDMCOUNT
216cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)),	\
217	$(sub_cmd_record_mcount))
218endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
219
220ifdef CONFIG_STACK_VALIDATION
221ifndef CONFIG_LTO_CLANG
222
223__objtool_obj := $(objtree)/tools/objtool/objtool
224
225# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
226# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
227# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
228cmd_objtool = $(if $(patsubst y%,, \
229	$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
230	$(__objtool_obj) $(objtool_args) $@)
231objtool_obj = $(if $(patsubst y%,, \
232	$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
233	$(__objtool_obj))
234
235endif # CONFIG_LTO_CLANG
236endif # CONFIG_STACK_VALIDATION
237
238# Rebuild all objects when objtool changes, or is enabled/disabled.
239objtool_dep = $(objtool_obj)					\
240	      $(wildcard include/config/ORC_UNWINDER		\
241			 include/config/STACK_VALIDATION)
242
243ifdef CONFIG_TRIM_UNUSED_KSYMS
244cmd_gen_ksymdeps = \
245	$(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd
246
247# List module undefined symbols
248undefined_syms = $(NM) $< | $(AWK) '$$1 == "U" { printf("%s%s", x++ ? " " : "", $$2) }';
249endif
250
251define rule_cc_o_c
252	$(call cmd_and_fixdep,cc_o_c)
253	$(call cmd,gen_ksymdeps)
254	$(call cmd,checksrc)
255	$(call cmd,checkdoc)
256	$(call cmd,objtool)
257	$(call cmd,modversions_c)
258	$(call cmd,record_mcount)
259endef
260
261define rule_as_o_S
262	$(call cmd_and_fixdep,as_o_S)
263	$(call cmd,gen_ksymdeps)
264	$(call cmd,objtool)
265	$(call cmd,modversions_S)
266endef
267
268# Built-in and composite module parts
269$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
270	$(call if_changed_rule,cc_o_c)
271	$(call cmd,force_checksrc)
272
273cmd_mod = { \
274	echo $(if $($*-objs)$($*-y)$($*-m), $(addprefix $(obj)/, $($*-objs) $($*-y) $($*-m)), $(@:.mod=.o)); \
275	$(undefined_syms) echo; \
276	} > $@
277
278$(obj)/%.mod: $(obj)/%.o FORCE
279	$(call if_changed,mod)
280
281quiet_cmd_cc_lst_c = MKLST   $@
282      cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
283		     $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
284				     System.map $(OBJDUMP) > $@
285
286$(obj)/%.lst: $(src)/%.c FORCE
287	$(call if_changed_dep,cc_lst_c)
288
289# Compile assembler sources (.S)
290# ---------------------------------------------------------------------------
291
292# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
293# or a file that it includes, in order to get versioned symbols. We build a
294# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
295# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
296#
297# This is convoluted. The .S file must first be preprocessed to run guards and
298# expand names, then the resulting exports must be constructed into plain
299# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
300# to make the genksyms input.
301#
302# These mirror gensymtypes_c and co above, keep them in synch.
303cmd_gensymtypes_S =                                                         \
304   { echo "\#include <linux/kernel.h>" ;                                    \
305     echo "\#include <asm/asm-prototypes.h>" ;                              \
306    $(CPP) $(a_flags) $< |                                                  \
307     grep "\<___EXPORT_SYMBOL\>" |                                          \
308     sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ; } | \
309    $(CPP) -D__GENKSYMS__ $(c_flags) -xc - |                                \
310    scripts/genksyms/genksyms $(if $(1), -T $(2))                           \
311     $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS))                             \
312     $(if $(KBUILD_PRESERVE),-p)                                            \
313     -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
314
315quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
316cmd_cc_symtypes_S =                                                         \
317    $(call cmd_gensymtypes_S,true,$@) >/dev/null;                           \
318    test -s $@ || rm -f $@
319
320$(obj)/%.symtypes : $(src)/%.S FORCE
321	$(call cmd,cc_symtypes_S)
322
323
324quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
325cmd_cpp_s_S       = $(CPP) $(a_flags) -o $@ $<
326
327$(obj)/%.s: $(src)/%.S FORCE
328	$(call if_changed_dep,cpp_s_S)
329
330quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
331      cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
332
333ifdef CONFIG_ASM_MODVERSIONS
334
335# versioning matches the C process described above, with difference that
336# we parse asm-prototypes.h C header to get function definitions.
337
338cmd_modversions_S =								\
339	if $(OBJDUMP) -h $@ | grep -q __ksymtab; then				\
340		$(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
341		    > $(@D)/.tmp_$(@F:.o=.ver);					\
342										\
343		$(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ 		\
344			-T $(@D)/.tmp_$(@F:.o=.ver);				\
345		mv -f $(@D)/.tmp_$(@F) $@;					\
346		rm -f $(@D)/.tmp_$(@F:.o=.ver);					\
347	fi
348endif
349
350$(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE
351	$(call if_changed_rule,as_o_S)
352
353targets += $(filter-out $(subdir-builtin), $(real-obj-y))
354targets += $(filter-out $(subdir-modorder), $(real-obj-m))
355targets += $(real-dtb-y) $(lib-y) $(always-y) $(MAKECMDGOALS)
356
357# Linker scripts preprocessor (.lds.S -> .lds)
358# ---------------------------------------------------------------------------
359quiet_cmd_cpp_lds_S = LDS     $@
360      cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
361	                     -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
362
363$(obj)/%.lds: $(src)/%.lds.S FORCE
364	$(call if_changed_dep,cpp_lds_S)
365
366# ASN.1 grammar
367# ---------------------------------------------------------------------------
368quiet_cmd_asn1_compiler = ASN.1   $(basename $@).[ch]
369      cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
370				$(basename $@).c $(basename $@).h
371
372$(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
373	$(call cmd,asn1_compiler)
374
375# Build the compiled-in targets
376# ---------------------------------------------------------------------------
377
378# To build objects in subdirs, we need to descend into the directories
379$(subdir-builtin): $(obj)/%/built-in.a: $(obj)/% ;
380$(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ;
381
382# combine symversions for later processing
383quiet_cmd_update_lto_symversions = SYMVER  $@
384ifeq ($(CONFIG_LTO_CLANG) $(CONFIG_MODVERSIONS),y y)
385      cmd_update_lto_symversions =					\
386	rm -f $@.symversions						\
387	$(foreach n, $(filter-out FORCE,$^),				\
388		$(if $(wildcard $(n).symversions),			\
389			; cat $(n).symversions >> $@.symversions))
390else
391      cmd_update_lto_symversions = echo >/dev/null
392endif
393
394#
395# Rule to compile a set of .o files into one .a file (without symbol table)
396#
397
398quiet_cmd_ar_builtin = AR      $@
399      cmd_ar_builtin = rm -f $@; $(AR) cDPrST $@ $(real-prereqs)
400
401quiet_cmd_ar_and_symver = AR      $@
402      cmd_ar_and_symver = $(cmd_update_lto_symversions); $(cmd_ar_builtin)
403
404$(obj)/built-in.a: $(real-obj-y) FORCE
405	$(call if_changed,ar_and_symver)
406
407#
408# Rule to create modules.order file
409#
410# Create commands to either record .ko file or cat modules.order from
411# a subdirectory
412# Add $(obj-m) as the prerequisite to avoid updating the timestamp of
413# modules.order unless contained modules are updated.
414
415cmd_modules_order = { $(foreach m, $(real-prereqs), \
416	$(if $(filter %/modules.order, $m), cat $m, echo $(patsubst %.o,%.ko,$m));) :; } \
417	| $(AWK) '!x[$$0]++' - > $@
418
419$(obj)/modules.order: $(obj-m) FORCE
420	$(call if_changed,modules_order)
421
422#
423# Rule to compile a set of .o files into one .a file (with symbol table)
424#
425quiet_cmd_ar_lib = AR      $@
426      cmd_ar_lib = $(cmd_update_lto_symversions); $(cmd_ar)
427
428$(obj)/lib.a: $(lib-y) FORCE
429	$(call if_changed,ar_lib)
430
431# NOTE:
432# Do not replace $(filter %.o,^) with $(real-prereqs). When a single object
433# module is turned into a multi object module, $^ will contain header file
434# dependencies recorded in the .*.cmd file.
435ifdef CONFIG_LTO_CLANG
436quiet_cmd_link_multi-m = AR [M]  $@
437cmd_link_multi-m =						\
438	$(cmd_update_lto_symversions);				\
439	rm -f $@; 						\
440	$(AR) cDPrsT $@ $(filter %.o,$^)
441else
442quiet_cmd_link_multi-m = LD [M]  $@
443      cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(filter %.o,$^)
444endif
445
446$(multi-obj-m): FORCE
447	$(call if_changed,link_multi-m)
448$(call multi_depend, $(multi-obj-m), .o, -objs -y -m)
449
450targets += $(multi-obj-m)
451targets := $(filter-out $(PHONY), $(targets))
452
453# Add intermediate targets:
454# When building objects with specific suffix patterns, add intermediate
455# targets that the final targets are derived from.
456intermediate_targets = $(foreach sfx, $(2), \
457				$(patsubst %$(strip $(1)),%$(sfx), \
458					$(filter %$(strip $(1)), $(targets))))
459# %.asn1.o <- %.asn1.[ch] <- %.asn1
460# %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
461# %.lex.o <- %.lex.c <- %.l
462# %.tab.o <- %.tab.[ch] <- %.y
463targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
464	   $(call intermediate_targets, .dtb.o, .dtb.S .dtb) \
465	   $(call intermediate_targets, .lex.o, .lex.c) \
466	   $(call intermediate_targets, .tab.o, .tab.c .tab.h)
467
468# Build
469# ---------------------------------------------------------------------------
470
471ifdef single-build
472
473KBUILD_SINGLE_TARGETS := $(filter $(obj)/%, $(KBUILD_SINGLE_TARGETS))
474
475curdir-single := $(sort $(foreach x, $(KBUILD_SINGLE_TARGETS), \
476			$(if $(filter $(x) $(basename $(x)).o, $(targets)), $(x))))
477
478# Handle single targets without any rule: show "Nothing to be done for ..." or
479# "No rule to make target ..." depending on whether the target exists.
480unknown-single := $(filter-out $(addsuffix /%, $(subdir-ym)), \
481			$(filter-out $(curdir-single), $(KBUILD_SINGLE_TARGETS)))
482
483single-subdirs := $(foreach d, $(subdir-ym), \
484			$(if $(filter $(d)/%, $(KBUILD_SINGLE_TARGETS)), $(d)))
485
486__build: $(curdir-single) $(single-subdirs)
487ifneq ($(unknown-single),)
488	$(Q)$(MAKE) -f /dev/null $(unknown-single)
489endif
490	@:
491
492ifeq ($(curdir-single),)
493# Nothing to do in this directory. Do not include any .*.cmd file for speed-up
494targets :=
495else
496targets += $(curdir-single)
497endif
498
499else
500
501__build: $(if $(KBUILD_BUILTIN), $(targets-for-builtin)) \
502	 $(if $(KBUILD_MODULES), $(targets-for-modules)) \
503	 $(subdir-ym) $(always-y)
504	@:
505
506endif
507
508# Descending
509# ---------------------------------------------------------------------------
510
511PHONY += $(subdir-ym)
512$(subdir-ym):
513	$(Q)$(MAKE) $(build)=$@ \
514	$(if $(filter $@/, $(KBUILD_SINGLE_TARGETS)),single-build=) \
515	need-builtin=$(if $(filter $@/built-in.a, $(subdir-builtin)),1) \
516	need-modorder=$(if $(filter $@/modules.order, $(subdir-modorder)),1)
517
518# Add FORCE to the prequisites of a target to force it to be always rebuilt.
519# ---------------------------------------------------------------------------
520
521PHONY += FORCE
522
523FORCE:
524
525# Read all saved command lines and dependencies for the $(targets) we
526# may be building above, using $(if_changed{,_dep}). As an
527# optimization, we don't need to read them if the target does not
528# exist, we will rebuild anyway in that case.
529
530existing-targets := $(wildcard $(sort $(targets)))
531
532-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
533
534# Create directories for object files if they do not exist
535obj-dirs := $(sort $(patsubst %/,%, $(dir $(targets))))
536# If targets exist, their directories apparently exist. Skip mkdir.
537existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))
538obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))
539ifneq ($(obj-dirs),)
540$(shell mkdir -p $(obj-dirs))
541endif
542
543.PHONY: $(PHONY)
544