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 := 19targets := 20subdir-y := 21subdir-m := 22EXTRA_AFLAGS := 23EXTRA_CFLAGS := 24EXTRA_CPPFLAGS := 25EXTRA_LDFLAGS := 26asflags-y := 27ccflags-y := 28cppflags-y := 29ldflags-y := 30 31subdir-asflags-y := 32subdir-ccflags-y := 33 34# Read auto.conf if it exists, otherwise ignore 35-include include/config/auto.conf 36 37include scripts/Kbuild.include 38 39# The filename Kbuild has precedence over Makefile 40kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src)) 41kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile) 42include $(kbuild-file) 43 44include scripts/Makefile.lib 45 46# Do not include host rules unless needed 47ifneq ($(hostprogs-y)$(hostprogs-m)$(hostlibs-y)$(hostlibs-m)$(hostcxxlibs-y)$(hostcxxlibs-m),) 48include scripts/Makefile.host 49endif 50 51ifndef obj 52$(warning kbuild: Makefile.build is included improperly) 53endif 54 55ifeq ($(need-modorder),) 56ifneq ($(obj-m),) 57$(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.) 58$(warning You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.) 59endif 60endif 61 62# =========================================================================== 63 64ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),) 65lib-target := $(obj)/lib.a 66real-obj-y += $(obj)/lib-ksyms.o 67endif 68 69ifneq ($(strip $(real-obj-y) $(need-builtin)),) 70builtin-target := $(obj)/built-in.a 71endif 72 73ifeq ($(CONFIG_MODULES)$(need-modorder),y1) 74modorder-target := $(obj)/modules.order 75endif 76 77mod-targets := $(patsubst %.o, %.mod, $(obj-m)) 78 79# Linus' kernel sanity checking tool 80ifeq ($(KBUILD_CHECKSRC),1) 81 quiet_cmd_checksrc = CHECK $< 82 cmd_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< 83else ifeq ($(KBUILD_CHECKSRC),2) 84 quiet_cmd_force_checksrc = CHECK $< 85 cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< 86endif 87 88ifneq ($(KBUILD_EXTRA_WARN),) 89 cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $< 90endif 91 92# Compile C sources (.c) 93# --------------------------------------------------------------------------- 94 95quiet_cmd_cc_s_c = CC $(quiet_modtag) $@ 96 cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS) $(CC_FLAGS_LTO), $(c_flags)) $(DISABLE_LTO) -fverbose-asm -S -o $@ $< 97 98$(obj)/%.s: $(src)/%.c FORCE 99 $(call if_changed_dep,cc_s_c) 100 101quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@ 102cmd_cpp_i_c = $(CPP) $(c_flags) -o $@ $< 103 104$(obj)/%.i: $(src)/%.c FORCE 105 $(call if_changed_dep,cpp_i_c) 106 107# These mirror gensymtypes_S and co below, keep them in synch. 108cmd_gensymtypes_c = \ 109 $(CPP) -D__GENKSYMS__ $(c_flags) $< | \ 110 scripts/genksyms/genksyms $(if $(1), -T $(2)) \ 111 $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \ 112 $(if $(KBUILD_PRESERVE),-p) \ 113 -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null)) 114 115quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@ 116cmd_cc_symtypes_c = \ 117 $(call cmd_gensymtypes_c,true,$@) >/dev/null; \ 118 test -s $@ || rm -f $@ 119 120$(obj)/%.symtypes : $(src)/%.c FORCE 121 $(call cmd,cc_symtypes_c) 122 123# LLVM assembly 124# Generate .ll files from .c 125quiet_cmd_cc_ll_c = CC $(quiet_modtag) $@ 126 cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $< 127 128$(obj)/%.ll: $(src)/%.c FORCE 129 $(call if_changed_dep,cc_ll_c) 130 131# C (.c) files 132# The C file is compiled and updated dependency information is generated. 133# (See cmd_cc_o_c + relevant part of rule_cc_o_c) 134 135quiet_cmd_cc_o_c = CC $(quiet_modtag) $@ 136 cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< 137 138ifdef CONFIG_MODVERSIONS 139# When module versioning is enabled the following steps are executed: 140# o compile a <file>.o from <file>.c 141# o if <file>.o doesn't contain a __ksymtab version, i.e. does 142# not export symbols, it's done. 143# o otherwise, we calculate symbol versions using the good old 144# genksyms on the preprocessed source and postprocess them in a way 145# that they are usable as a linker script 146# o generate .tmp_<file>.o from <file>.o using the linker to 147# replace the unresolved symbols __crc_exported_symbol with 148# the actual value of the checksum generated by genksyms 149# o remove .tmp_<file>.o to <file>.o 150 151ifdef CONFIG_LTO_CLANG 152# Generate .o.symversions files for each .o with exported symbols, and link these 153# to the kernel and/or modules at the end. 154cmd_modversions_c = \ 155 if $(LLVM_NM) $@ | grep -q __ksymtab; then \ 156 $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \ 157 > $@.symversions; \ 158 fi; 159else 160cmd_modversions_c = \ 161 if $(OBJDUMP) -h $@ | grep -q __ksymtab; then \ 162 $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \ 163 > $(@D)/.tmp_$(@F:.o=.ver); \ 164 \ 165 $(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ \ 166 -T $(@D)/.tmp_$(@F:.o=.ver); \ 167 mv -f $(@D)/.tmp_$(@F) $@; \ 168 rm -f $(@D)/.tmp_$(@F:.o=.ver); \ 169 fi 170endif 171endif 172 173ifdef CONFIG_FTRACE_MCOUNT_RECORD 174ifndef CC_USING_RECORD_MCOUNT 175# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl 176ifdef BUILD_C_RECORDMCOUNT 177ifeq ("$(origin RECORDMCOUNT_WARN)", "command line") 178 RECORDMCOUNT_FLAGS = -w 179endif 180 181ifdef CONFIG_LTO_CLANG 182# With LTO, we postpone running recordmcount until after the LTO link step, so 183# let's export the parameters for the link script. 184export RECORDMCOUNT_FLAGS 185else 186# Due to recursion, we must skip empty.o. 187# The empty.o file is created in the make process in order to determine 188# the target endianness and word size. It is made before all other C 189# files, including recordmcount. 190sub_cmd_record_mcount = \ 191 if [ $(@) != "scripts/mod/empty.o" ]; then \ 192 $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \ 193 fi; 194endif 195 196recordmcount_source := $(srctree)/scripts/recordmcount.c \ 197 $(srctree)/scripts/recordmcount.h 198else 199sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \ 200 "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \ 201 "$(if $(CONFIG_64BIT),64,32)" \ 202 "$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \ 203 "$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \ 204 "$(if $(part-of-module),1,0)" "$(@)"; 205 206recordmcount_source := $(srctree)/scripts/recordmcount.pl 207endif # BUILD_C_RECORDMCOUNT 208ifndef CONFIG_LTO_CLANG 209cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), \ 210 $(sub_cmd_record_mcount)) 211endif # CONFIG_LTO_CLANG 212endif # CC_USING_RECORD_MCOUNT 213endif # CONFIG_FTRACE_MCOUNT_RECORD 214 215ifdef CONFIG_STACK_VALIDATION 216ifneq ($(SKIP_STACK_VALIDATION),1) 217 218__objtool_obj := $(objtree)/tools/objtool/objtool 219 220objtool_args = $(if $(CONFIG_UNWINDER_ORC),orc generate,check) 221 222objtool_args += $(if $(part-of-module), --module,) 223 224ifndef CONFIG_FRAME_POINTER 225objtool_args += --no-fp 226endif 227ifdef CONFIG_GCOV_KERNEL 228objtool_args += --no-unreachable 229endif 230ifdef CONFIG_RETPOLINE 231 objtool_args += --retpoline 232endif 233ifdef CONFIG_X86_SMAP 234 objtool_args += --uaccess 235endif 236 237# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory 238# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file 239# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file 240cmd_objtool = $(if $(patsubst y%,, \ 241 $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \ 242 $(__objtool_obj) $(objtool_args) $@) 243objtool_obj = $(if $(patsubst y%,, \ 244 $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \ 245 $(__objtool_obj)) 246 247endif # SKIP_STACK_VALIDATION 248endif # CONFIG_STACK_VALIDATION 249 250# Rebuild all objects when objtool changes, or is enabled/disabled. 251objtool_dep = $(objtool_obj) \ 252 $(wildcard include/config/orc/unwinder.h \ 253 include/config/stack/validation.h) 254 255ifdef CONFIG_TRIM_UNUSED_KSYMS 256cmd_gen_ksymdeps = \ 257 $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd 258 259# List module undefined symbols 260undefined_syms = $(NM) $< | $(AWK) '$$1 == "U" { printf("%s%s", x++ ? " " : "", $$2) }'; 261endif 262 263define rule_cc_o_c 264 $(call cmd_and_fixdep,cc_o_c) 265 $(call cmd,gen_ksymdeps) 266 $(call cmd,checksrc) 267 $(call cmd,checkdoc) 268 $(call cmd,objtool) 269 $(call cmd,modversions_c) 270 $(call cmd,record_mcount) 271endef 272 273define rule_as_o_S 274 $(call cmd_and_fixdep,as_o_S) 275 $(call cmd,gen_ksymdeps) 276 $(call cmd,objtool) 277 $(call cmd,modversions_S) 278endef 279 280# Built-in and composite module parts 281.SECONDEXPANSION: 282$(obj)/%.o: $(src)/%.c $(recordmcount_source) $$(objtool_dep) FORCE 283 $(call if_changed_rule,cc_o_c) 284 $(call cmd,force_checksrc) 285 286cmd_mod = { \ 287 echo $(if $($*-objs)$($*-y)$($*-m), $(addprefix $(obj)/, $($*-objs) $($*-y) $($*-m)), $(@:.mod=.o)); \ 288 $(undefined_syms) echo; \ 289 } > $@ 290 291$(obj)/%.mod: $(obj)/%.o FORCE 292 $(call if_changed,mod) 293 294targets += $(mod-targets) 295 296quiet_cmd_cc_lst_c = MKLST $@ 297 cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \ 298 $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \ 299 System.map $(OBJDUMP) > $@ 300 301$(obj)/%.lst: $(src)/%.c FORCE 302 $(call if_changed_dep,cc_lst_c) 303 304# Compile assembler sources (.S) 305# --------------------------------------------------------------------------- 306 307# .S file exports must have their C prototypes defined in asm/asm-prototypes.h 308# or a file that it includes, in order to get versioned symbols. We build a 309# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from 310# the .S file (with trailing ';'), and run genksyms on that, to extract vers. 311# 312# This is convoluted. The .S file must first be preprocessed to run guards and 313# expand names, then the resulting exports must be constructed into plain 314# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed 315# to make the genksyms input. 316# 317# These mirror gensymtypes_c and co above, keep them in synch. 318cmd_gensymtypes_S = \ 319 { echo "\#include <linux/kernel.h>" ; \ 320 echo "\#include <asm/asm-prototypes.h>" ; \ 321 $(CPP) $(a_flags) $< | \ 322 grep "\<___EXPORT_SYMBOL\>" | \ 323 sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ; } | \ 324 $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | \ 325 scripts/genksyms/genksyms $(if $(1), -T $(2)) \ 326 $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \ 327 $(if $(KBUILD_PRESERVE),-p) \ 328 -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null)) 329 330quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@ 331cmd_cc_symtypes_S = \ 332 $(call cmd_gensymtypes_S,true,$@) >/dev/null; \ 333 test -s $@ || rm -f $@ 334 335$(obj)/%.symtypes : $(src)/%.S FORCE 336 $(call cmd,cc_symtypes_S) 337 338 339quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@ 340cmd_cpp_s_S = $(CPP) $(a_flags) -o $@ $< 341 342$(obj)/%.s: $(src)/%.S FORCE 343 $(call if_changed_dep,cpp_s_S) 344 345quiet_cmd_as_o_S = AS $(quiet_modtag) $@ 346 cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $< 347 348ifdef CONFIG_ASM_MODVERSIONS 349 350# versioning matches the C process described above, with difference that 351# we parse asm-prototypes.h C header to get function definitions. 352 353cmd_modversions_S = \ 354 if $(OBJDUMP) -h $@ | grep -q __ksymtab; then \ 355 $(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \ 356 > $(@D)/.tmp_$(@F:.o=.ver); \ 357 \ 358 $(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ \ 359 -T $(@D)/.tmp_$(@F:.o=.ver); \ 360 mv -f $(@D)/.tmp_$(@F) $@; \ 361 rm -f $(@D)/.tmp_$(@F:.o=.ver); \ 362 fi 363endif 364 365$(obj)/%.o: $(src)/%.S $$(objtool_dep) FORCE 366 $(call if_changed_rule,as_o_S) 367 368targets += $(filter-out $(subdir-obj-y), $(real-obj-y)) $(real-obj-m) $(lib-y) 369targets += $(extra-y) $(MAKECMDGOALS) $(always) 370 371# Linker scripts preprocessor (.lds.S -> .lds) 372# --------------------------------------------------------------------------- 373quiet_cmd_cpp_lds_S = LDS $@ 374 cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \ 375 -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $< 376 377$(obj)/%.lds: $(src)/%.lds.S FORCE 378 $(call if_changed_dep,cpp_lds_S) 379 380# ASN.1 grammar 381# --------------------------------------------------------------------------- 382quiet_cmd_asn1_compiler = ASN.1 $(basename $@).[ch] 383 cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \ 384 $(basename $@).c $(basename $@).h 385 386$(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler 387 $(call cmd,asn1_compiler) 388 389# Build the compiled-in targets 390# --------------------------------------------------------------------------- 391 392# To build objects in subdirs, we need to descend into the directories 393$(sort $(subdir-obj-y)): $(subdir-ym) ; 394 395# combine symversions for later processing 396quiet_cmd_update_lto_symversions = SYMVER $@ 397ifeq ($(CONFIG_LTO_CLANG) $(CONFIG_MODVERSIONS),y y) 398 cmd_update_lto_symversions = \ 399 rm -f $@.symversions; \ 400 for i in $(foreach n, \ 401 $(filter-out FORCE,$^), \ 402 $(if $(wildcard $(n).symversions),$(n))); do \ 403 cat $$i.symversions >> $@.symversions; \ 404 done 405else 406 cmd_update_lto_symversions = echo >/dev/null 407endif 408 409# 410# Rule to compile a set of .o files into one .a file (without symbol table) 411# 412ifdef builtin-target 413 414quiet_cmd_ar_builtin = AR $@ 415 cmd_ar_builtin = rm -f $@; $(AR) cDPrST $@ $(real-prereqs) 416 417quiet_cmd_ar_and_symver = AR $@ 418 cmd_ar_and_symver = $(cmd_update_lto_symversions); $(cmd_ar_builtin) 419 420$(builtin-target): $(real-obj-y) FORCE 421 $(call if_changed,ar_and_symver) 422 423targets += $(builtin-target) 424endif # builtin-target 425 426# 427# Rule to create modules.order file 428# 429# Create commands to either record .ko file or cat modules.order from 430# a subdirectory 431$(modorder-target): $(subdir-ym) FORCE 432 $(Q){ $(foreach m, $(modorder), \ 433 $(if $(filter %/modules.order, $m), cat $m, echo $m);) :; } \ 434 | $(AWK) '!x[$$0]++' - > $@ 435 436# 437# Rule to compile a set of .o files into one .a file (with symbol table) 438# 439ifdef lib-target 440 441quiet_cmd_ar_lib = AR $@ 442 cmd_ar_lib = $(cmd_update_lto_symversions); $(cmd_ar) 443 444$(lib-target): $(lib-y) FORCE 445 $(call if_changed,ar_lib) 446 447targets += $(lib-target) 448 449dummy-object = $(obj)/.lib_exports.o 450ksyms-lds = $(dot-target).lds 451 452ifdef CONFIG_LTO_CLANG 453# Objdump doesn't understand LLVM IR. Use llvm-nm to dump symbols. 454dump_export_list = $(LLVM_NM) 455else 456dump_export_list = $(OBJDUMP) -h 457endif 458 459quiet_cmd_export_list = EXPORTS $@ 460cmd_export_list = $(dump_export_list) $< | \ 461 sed -ne '/___ksymtab/s/.*+\([^ ]*\).*/EXTERN(\1)/p' >$(ksyms-lds);\ 462 rm -f $(dummy-object);\ 463 echo | $(CC) $(a_flags) -c -o $(dummy-object) -x assembler -;\ 464 $(LD) $(ld_flags) -r -o $@ -T $(ksyms-lds) $(dummy-object);\ 465 rm $(dummy-object) $(ksyms-lds) 466 467$(obj)/lib-ksyms.o: $(lib-target) FORCE 468 $(call if_changed,export_list) 469 470targets += $(obj)/lib-ksyms.o 471 472endif 473 474# NOTE: 475# Do not replace $(filter %.o,^) with $(real-prereqs). When a single object 476# module is turned into a multi object module, $^ will contain header file 477# dependencies recorded in the .*.cmd file. 478ifdef CONFIG_LTO_CLANG 479quiet_cmd_link_multi-m = AR [M] $@ 480cmd_link_multi-m = \ 481 $(cmd_update_lto_symversions); \ 482 rm -f $@; \ 483 $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(filter %.o,$^) 484else 485quiet_cmd_link_multi-m = LD [M] $@ 486 cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(filter %.o,$^) 487endif 488 489$(multi-used-m): FORCE 490 $(call if_changed,link_multi-m) 491$(call multi_depend, $(multi-used-m), .o, -objs -y -m) 492 493targets += $(multi-used-m) 494targets := $(filter-out $(PHONY), $(targets)) 495 496# Add intermediate targets: 497# When building objects with specific suffix patterns, add intermediate 498# targets that the final targets are derived from. 499intermediate_targets = $(foreach sfx, $(2), \ 500 $(patsubst %$(strip $(1)),%$(sfx), \ 501 $(filter %$(strip $(1)), $(targets)))) 502# %.asn1.o <- %.asn1.[ch] <- %.asn1 503# %.dtb.o <- %.dtb.S <- %.dtb <- %.dts 504# %.lex.o <- %.lex.c <- %.l 505# %.tab.o <- %.tab.[ch] <- %.y 506targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \ 507 $(call intermediate_targets, .dtb.o, .dtb.S .dtb) \ 508 $(call intermediate_targets, .lex.o, .lex.c) \ 509 $(call intermediate_targets, .tab.o, .tab.c .tab.h) 510 511# Build 512# --------------------------------------------------------------------------- 513 514ifdef single-build 515 516curdir-single := $(sort $(foreach x, $(KBUILD_SINGLE_TARGETS), \ 517 $(if $(filter $(x) $(basename $(x)).o, $(targets)), $(x)))) 518 519# Handle single targets without any rule: show "Nothing to be done for ..." or 520# "No rule to make target ..." depending on whether the target exists. 521unknown-single := $(filter-out $(addsuffix /%, $(subdir-ym)), \ 522 $(filter $(obj)/%, \ 523 $(filter-out $(curdir-single), \ 524 $(KBUILD_SINGLE_TARGETS)))) 525 526__build: $(curdir-single) $(subdir-ym) 527ifneq ($(unknown-single),) 528 $(Q)$(MAKE) -f /dev/null $(unknown-single) 529endif 530 @: 531 532ifeq ($(curdir-single),) 533# Nothing to do in this directory. Do not include any .*.cmd file for speed-up 534targets := 535else 536targets += $(curdir-single) 537endif 538 539else 540 541__build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \ 542 $(if $(KBUILD_MODULES),$(obj-m) $(mod-targets) $(modorder-target)) \ 543 $(subdir-ym) $(always) 544 @: 545 546endif 547 548# Descending 549# --------------------------------------------------------------------------- 550 551PHONY += $(subdir-ym) 552$(subdir-ym): 553 $(Q)$(MAKE) $(build)=$@ \ 554 $(if $(filter $@/, $(KBUILD_SINGLE_TARGETS)),single-build=) \ 555 need-builtin=$(if $(filter $@/built-in.a, $(subdir-obj-y)),1) \ 556 need-modorder=$(if $(need-modorder),$(if $(filter $@/modules.order, $(modorder)),1)) 557 558# Add FORCE to the prequisites of a target to force it to be always rebuilt. 559# --------------------------------------------------------------------------- 560 561PHONY += FORCE 562 563FORCE: 564 565# Read all saved command lines and dependencies for the $(targets) we 566# may be building above, using $(if_changed{,_dep}). As an 567# optimization, we don't need to read them if the target does not 568# exist, we will rebuild anyway in that case. 569 570existing-targets := $(wildcard $(sort $(targets))) 571 572-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd) 573 574ifdef building_out_of_srctree 575# Create directories for object files if they do not exist 576obj-dirs := $(sort $(obj) $(patsubst %/,%, $(dir $(targets)))) 577# If targets exist, their directories apparently exist. Skip mkdir. 578existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets)))) 579obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs))) 580ifneq ($(obj-dirs),) 581$(shell mkdir -p $(obj-dirs)) 582endif 583endif 584 585.PHONY: $(PHONY) 586