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