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# 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 CONFIG_LTO_CLANG
92targets-for-modules += $(patsubst %.o, %.lto.o, $(filter %.o, $(obj-m)))
93endif
94
95ifdef need-modorder
96targets-for-modules += $(obj)/modules.order
97endif
98
99targets += $(targets-for-builtin) $(targets-for-modules)
100
101# Linus' kernel sanity checking tool
102ifeq ($(KBUILD_CHECKSRC),1)
103 quiet_cmd_checksrc = CHECK $<
104 cmd_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
105else ifeq ($(KBUILD_CHECKSRC),2)
106 quiet_cmd_force_checksrc = CHECK $<
107 cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
108endif
109
110ifneq ($(KBUILD_EXTRA_WARN),)
111 cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $<
112endif
113
114# Compile C sources (.c)
115# ---------------------------------------------------------------------------
116
117quiet_cmd_cc_s_c = CC $(quiet_modtag) $@
118 cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS) $(CC_FLAGS_LTO), $(c_flags)) -fverbose-asm -S -o $@ $<
119
120$(obj)/%.s: $(src)/%.c FORCE
121 $(call if_changed_dep,cc_s_c)
122
123quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
124cmd_cpp_i_c = $(CPP) $(c_flags) -o $@ $<
125
126$(obj)/%.i: $(src)/%.c FORCE
127 $(call if_changed_dep,cpp_i_c)
128
129# These mirror gensymtypes_S and co below, keep them in synch.
130cmd_gensymtypes_c = \
131 $(CPP) -D__GENKSYMS__ $(c_flags) $< | \
132 scripts/genksyms/genksyms $(if $(1), -T $(2)) \
133 $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \
134 $(if $(KBUILD_PRESERVE),-p) \
135 -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
136
137quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
138cmd_cc_symtypes_c = \
139 $(call cmd_gensymtypes_c,true,$@) >/dev/null; \
140 test -s $@ || rm -f $@
141
142$(obj)/%.symtypes : $(src)/%.c FORCE
143 $(call cmd,cc_symtypes_c)
144
145# LLVM assembly
146# Generate .ll files from .c
147quiet_cmd_cc_ll_c = CC $(quiet_modtag) $@
148 cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $<
149
150$(obj)/%.ll: $(src)/%.c FORCE
151 $(call if_changed_dep,cc_ll_c)
152
153# C (.c) files
154# The C file is compiled and updated dependency information is generated.
155# (See cmd_cc_o_c + relevant part of rule_cc_o_c)
156
157quiet_cmd_cc_o_c = CC $(quiet_modtag) $@
158 cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< $(cmd_objtool)
159
160ifdef CONFIG_MODVERSIONS
161# When module versioning is enabled the following steps are executed:
162# o compile a <file>.o from <file>.c
163# o if <file>.o doesn't contain a __ksymtab version, i.e. does
164# not export symbols, it's done.
165# o otherwise, we calculate symbol versions using the good old
166# genksyms on the preprocessed source and postprocess them in a way
167# that they are usable as a linker script
168# o generate .tmp_<file>.o from <file>.o using the linker to
169# replace the unresolved symbols __crc_exported_symbol with
170# the actual value of the checksum generated by genksyms
171# o remove .tmp_<file>.o to <file>.o
172
173ifdef CONFIG_LTO_CLANG
174# Generate .o.symversions files for each .o with exported symbols, and link these
175# to the kernel and/or modules at the end.
176cmd_modversions_c = \
177 if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then \
178 $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
179 > $@.symversions; \
180 else \
181 rm -f $@.symversions; \
182 fi;
183else
184cmd_modversions_c = \
185 if $(OBJDUMP) -h $@ | grep -q __ksymtab; then \
186 $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
187 > $(@D)/.tmp_$(@F:.o=.ver); \
188 \
189 $(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ \
190 -T $(@D)/.tmp_$(@F:.o=.ver); \
191 mv -f $(@D)/.tmp_$(@F) $@; \
192 rm -f $(@D)/.tmp_$(@F:.o=.ver); \
193 fi
194endif
195endif
196
197ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
198# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
199ifdef BUILD_C_RECORDMCOUNT
200ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
201 RECORDMCOUNT_FLAGS = -w
202endif
203# Due to recursion, we must skip empty.o.
204# The empty.o file is created in the make process in order to determine
205# the target endianness and word size. It is made before all other C
206# files, including recordmcount.
207sub_cmd_record_mcount = \
208 if [ $(@) != "scripts/mod/empty.o" ]; then \
209 $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
210 fi;
211recordmcount_source := $(srctree)/scripts/recordmcount.c \
212 $(srctree)/scripts/recordmcount.h
213else
214sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
215 "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
216 "$(if $(CONFIG_64BIT),64,32)" \
217 "$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
218 "$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
219 "$(if $(part-of-module),1,0)" "$(@)";
220recordmcount_source := $(srctree)/scripts/recordmcount.pl
221endif # BUILD_C_RECORDMCOUNT
222cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), \
223 $(sub_cmd_record_mcount))
224endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
225
226ifdef CONFIG_STACK_VALIDATION
227
228objtool := $(objtree)/tools/objtool/objtool
229
230objtool_args = \
231 $(if $(CONFIG_UNWINDER_ORC),orc generate,check) \
232 $(if $(part-of-module), --module) \
233 $(if $(CONFIG_FRAME_POINTER),, --no-fp) \
234 $(if $(CONFIG_GCOV_KERNEL)$(CONFIG_LTO_CLANG), --no-unreachable)\
235 $(if $(CONFIG_RETPOLINE), --retpoline) \
236 $(if $(CONFIG_X86_SMAP), --uaccess) \
237 $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount)
238
239cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
240cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
241
242endif # CONFIG_STACK_VALIDATION
243
244ifdef CONFIG_LTO_CLANG
245
246# Skip objtool for LLVM bitcode
247$(obj)/%.o: objtool-enabled :=
248
249else
250
251# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
252# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
253# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
254
255$(obj)/%.o: objtool-enabled = $(if $(filter-out y%, \
256 $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y)
257
258endif
259
260ifdef CONFIG_TRIM_UNUSED_KSYMS
261cmd_gen_ksymdeps = \
262 $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd
263
264# List module undefined symbols
265undefined_syms = $(NM) $< | $(AWK) '$$1 == "U" { printf("%s%s", x++ ? " " : "", $$2) }';
266endif
267
268define rule_cc_o_c
269 $(call cmd_and_fixdep,cc_o_c)
270 $(call cmd,gen_ksymdeps)
271 $(call cmd,checksrc)
272 $(call cmd,checkdoc)
273 $(call cmd,gen_objtooldep)
274 $(call cmd,modversions_c)
275 $(call cmd,record_mcount)
276endef
277
278define rule_as_o_S
279 $(call cmd_and_fixdep,as_o_S)
280 $(call cmd,gen_ksymdeps)
281 $(call cmd,gen_objtooldep)
282 $(call cmd,modversions_S)
283endef
284
285# Built-in and composite module parts
286$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
287 $(call if_changed_rule,cc_o_c)
288 $(call cmd,force_checksrc)
289
290ifdef CONFIG_LTO_CLANG
291# Module .o files may contain LLVM bitcode, compile them into native code
292# before ELF processing
293quiet_cmd_cc_lto_link_modules = LTO [M] $@
294cmd_cc_lto_link_modules = \
295 $(LD) $(ld_flags) -r -o $@ \
296 $(shell [ -s $(@:.lto.o=.o.symversions) ] && \
297 echo -T $(@:.lto.o=.o.symversions)) \
298 --whole-archive $(filter-out FORCE,$^) \
299 $(cmd_objtool)
300
301# objtool was skipped for LLVM bitcode, run it now that we have compiled
302# modules into native code
303$(obj)/%.lto.o: objtool-enabled = y
304$(obj)/%.lto.o: part-of-module := y
305
306$(obj)/%.lto.o: $(obj)/%.o FORCE
307 $(call if_changed,cc_lto_link_modules)
308endif
309
310cmd_mod = { \
311 echo $(if $($*-objs)$($*-y)$($*-m), $(addprefix $(obj)/, $($*-objs) $($*-y) $($*-m)), $(@:.mod=.o)); \
312 $(undefined_syms) echo; \
313 } > $@
314
315$(obj)/%.mod: $(obj)/%$(mod-prelink-ext).o FORCE
316 $(call if_changed,mod)
317
318quiet_cmd_cc_lst_c = MKLST $@
319 cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
320 $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
321 System.map $(OBJDUMP) > $@
322
323$(obj)/%.lst: $(src)/%.c FORCE
324 $(call if_changed_dep,cc_lst_c)
325
326# Compile assembler sources (.S)
327# ---------------------------------------------------------------------------
328
329# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
330# or a file that it includes, in order to get versioned symbols. We build a
331# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
332# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
333#
334# This is convoluted. The .S file must first be preprocessed to run guards and
335# expand names, then the resulting exports must be constructed into plain
336# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
337# to make the genksyms input.
338#
339# These mirror gensymtypes_c and co above, keep them in synch.
340cmd_gensymtypes_S = \
341 { echo "\#include <linux/kernel.h>" ; \
342 echo "\#include <asm/asm-prototypes.h>" ; \
343 $(CPP) $(a_flags) $< | \
344 grep "\<___EXPORT_SYMBOL\>" | \
345 sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ; } | \
346 $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | \
347 scripts/genksyms/genksyms $(if $(1), -T $(2)) \
348 $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \
349 $(if $(KBUILD_PRESERVE),-p) \
350 -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
351
352quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
353cmd_cc_symtypes_S = \
354 $(call cmd_gensymtypes_S,true,$@) >/dev/null; \
355 test -s $@ || rm -f $@
356
357$(obj)/%.symtypes : $(src)/%.S FORCE
358 $(call cmd,cc_symtypes_S)
359
360
361quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
362cmd_cpp_s_S = $(CPP) $(a_flags) -o $@ $<
363
364$(obj)/%.s: $(src)/%.S FORCE
365 $(call if_changed_dep,cpp_s_S)
366
367quiet_cmd_as_o_S = AS $(quiet_modtag) $@
368 cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $< $(cmd_objtool)
369
370ifdef CONFIG_ASM_MODVERSIONS
371
372# versioning matches the C process described above, with difference that
373# we parse asm-prototypes.h C header to get function definitions.
374
375cmd_modversions_S = \
376 if $(OBJDUMP) -h $@ | grep -q __ksymtab; then \
377 $(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
378 > $(@D)/.tmp_$(@F:.o=.ver); \
379 \
380 $(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ \
381 -T $(@D)/.tmp_$(@F:.o=.ver); \
382 mv -f $(@D)/.tmp_$(@F) $@; \
383 rm -f $(@D)/.tmp_$(@F:.o=.ver); \
384 fi
385endif
386
387$(obj)/%.o: $(src)/%.S FORCE
388 $(call if_changed_rule,as_o_S)
389
390targets += $(filter-out $(subdir-builtin), $(real-obj-y))
391targets += $(filter-out $(subdir-modorder), $(real-obj-m))
392targets += $(real-dtb-y) $(lib-y) $(always-y) $(MAKECMDGOALS)
393
394# Linker scripts preprocessor (.lds.S -> .lds)
395# ---------------------------------------------------------------------------
396quiet_cmd_cpp_lds_S = LDS $@
397 cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
398 -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
399
400$(obj)/%.lds: $(src)/%.lds.S FORCE
401 $(call if_changed_dep,cpp_lds_S)
402
403# ASN.1 grammar
404# ---------------------------------------------------------------------------
405quiet_cmd_asn1_compiler = ASN.1 $(basename $@).[ch]
406 cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
407 $(basename $@).c $(basename $@).h
408
409$(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
410 $(call cmd,asn1_compiler)
411
412# Build the compiled-in targets
413# ---------------------------------------------------------------------------
414
415# To build objects in subdirs, we need to descend into the directories
416$(subdir-builtin): $(obj)/%/built-in.a: $(obj)/% ;
417$(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ;
418
419# combine symversions for later processing
420ifeq ($(CONFIG_LTO_CLANG) $(CONFIG_MODVERSIONS),y y)
421 cmd_update_lto_symversions = \
422 rm -f $@.symversions \
423 $(foreach n, $(filter-out FORCE,$^), \
424 $(if $(shell test -s $(n).symversions && echo y), \
425 ; cat $(n).symversions >> $@.symversions))
426else
427 cmd_update_lto_symversions = echo >/dev/null
428endif
429
430#
431# Rule to compile a set of .o files into one .a file (without symbol table)
432#
433
434quiet_cmd_ar_builtin = AR $@
435 cmd_ar_builtin = rm -f $@; $(AR) cDPrST $@ $(real-prereqs)
436
437quiet_cmd_ar_and_symver = AR $@
438 cmd_ar_and_symver = $(cmd_update_lto_symversions); $(cmd_ar_builtin)
439
440$(obj)/built-in.a: $(real-obj-y) FORCE
441 $(call if_changed,ar_and_symver)
442
443#
444# Rule to create modules.order file
445#
446# Create commands to either record .ko file or cat modules.order from
447# a subdirectory
448# Add $(obj-m) as the prerequisite to avoid updating the timestamp of
449# modules.order unless contained modules are updated.
450
451cmd_modules_order = { $(foreach m, $(real-prereqs), \
452 $(if $(filter %/modules.order, $m), cat $m, echo $(patsubst %.o,%.ko,$m));) :; } \
453 | $(AWK) '!x[$$0]++' - > $@
454
455$(obj)/modules.order: $(obj-m) FORCE
456 $(call if_changed,modules_order)
457
458#
459# Rule to compile a set of .o files into one .a file (with symbol table)
460#
461quiet_cmd_ar_lib = AR $@
462 cmd_ar_lib = $(cmd_update_lto_symversions); $(cmd_ar)
463
464$(obj)/lib.a: $(lib-y) FORCE
465 $(call if_changed,ar_lib)
466
467# NOTE:
468# Do not replace $(filter %.o,^) with $(real-prereqs). When a single object
469# module is turned into a multi object module, $^ will contain header file
470# dependencies recorded in the .*.cmd file.
471ifdef CONFIG_LTO_CLANG
472quiet_cmd_link_multi-m = AR [M] $@
473cmd_link_multi-m = \
474 $(cmd_update_lto_symversions); \
475 rm -f $@; \
476 $(AR) cDPrsT $@ $(filter %.o,$^)
477else
478quiet_cmd_link_multi-m = LD [M] $@
479 cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(filter %.o,$^)
480endif
481
482$(multi-obj-m): FORCE
483 $(call if_changed,link_multi-m)
484$(call multi_depend, $(multi-obj-m), .o, -objs -y -m)
485
486targets += $(multi-obj-m)
487targets := $(filter-out $(PHONY), $(targets))
488
489# Add intermediate targets:
490# When building objects with specific suffix patterns, add intermediate
491# targets that the final targets are derived from.
492intermediate_targets = $(foreach sfx, $(2), \
493 $(patsubst %$(strip $(1)),%$(sfx), \
494 $(filter %$(strip $(1)), $(targets))))
495# %.asn1.o <- %.asn1.[ch] <- %.asn1
496# %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
497# %.lex.o <- %.lex.c <- %.l
498# %.tab.o <- %.tab.[ch] <- %.y
499targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
500 $(call intermediate_targets, .dtb.o, .dtb.S .dtb) \
501 $(call intermediate_targets, .lex.o, .lex.c) \
502 $(call intermediate_targets, .tab.o, .tab.c .tab.h)
503
504# Build
505# ---------------------------------------------------------------------------
506
507ifdef single-build
508
509KBUILD_SINGLE_TARGETS := $(filter $(obj)/%, $(KBUILD_SINGLE_TARGETS))
510
511curdir-single := $(sort $(foreach x, $(KBUILD_SINGLE_TARGETS), \
512 $(if $(filter $(x) $(basename $(x)).o, $(targets)), $(x))))
513
514# Handle single targets without any rule: show "Nothing to be done for ..." or
515# "No rule to make target ..." depending on whether the target exists.
516unknown-single := $(filter-out $(addsuffix /%, $(subdir-ym)), \
517 $(filter-out $(curdir-single), $(KBUILD_SINGLE_TARGETS)))
518
519single-subdirs := $(foreach d, $(subdir-ym), \
520 $(if $(filter $(d)/%, $(KBUILD_SINGLE_TARGETS)), $(d)))
521
522__build: $(curdir-single) $(single-subdirs)
523ifneq ($(unknown-single),)
524 $(Q)$(MAKE) -f /dev/null $(unknown-single)
525endif
526 @:
527
528ifeq ($(curdir-single),)
529# Nothing to do in this directory. Do not include any .*.cmd file for speed-up
530targets :=
531else
532targets += $(curdir-single)
533endif
534
535else
536
537__build: $(if $(KBUILD_BUILTIN), $(targets-for-builtin)) \
538 $(if $(KBUILD_MODULES), $(targets-for-modules)) \
539 $(subdir-ym) $(always-y)
540 @:
541
542endif
543
544# Descending
545# ---------------------------------------------------------------------------
546
547PHONY += $(subdir-ym)
548$(subdir-ym):
549 $(Q)$(MAKE) $(build)=$@ \
550 $(if $(filter $@/, $(KBUILD_SINGLE_TARGETS)),single-build=) \
551 need-builtin=$(if $(filter $@/built-in.a, $(subdir-builtin)),1) \
552 need-modorder=$(if $(filter $@/modules.order, $(subdir-modorder)),1)
553
554# Add FORCE to the prequisites of a target to force it to be always rebuilt.
555# ---------------------------------------------------------------------------
556
557PHONY += FORCE
558
559FORCE:
560
561# Read all saved command lines and dependencies for the $(targets) we
562# may be building above, using $(if_changed{,_dep}). As an
563# optimization, we don't need to read them if the target does not
564# exist, we will rebuild anyway in that case.
565
566existing-targets := $(wildcard $(sort $(targets)))
567
568-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
569
570# Create directories for object files if they do not exist
571obj-dirs := $(sort $(patsubst %/,%, $(dir $(targets))))
572# If targets exist, their directories apparently exist. Skip mkdir.
573existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))
574obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))
575ifneq ($(obj-dirs),)
576$(shell mkdir -p $(obj-dirs))
577endif
578
579.PHONY: $(PHONY)