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) 580