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 :=
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
56ifdef host-progs
57ifneq ($(hostprogs-y),$(host-progs))
58$(warning kbuild: $(obj)/Makefile - Usage of host-progs is deprecated. Please replace with hostprogs-y!)
59hostprogs-y += $(host-progs)
60endif
61endif
62
63# Do not include host rules unless needed
64ifneq ($(hostprogs-y)$(hostprogs-m)$(hostlibs-y)$(hostlibs-m)$(hostcxxlibs-y)$(hostcxxlibs-m),)
65include scripts/Makefile.host
66endif
67
68ifndef obj
69$(warning kbuild: Makefile.build is included improperly)
70endif
71
72# ===========================================================================
73
74ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
75lib-target := $(obj)/lib.a
76real-obj-y += $(obj)/lib-ksyms.o
77endif
78
79ifneq ($(strip $(real-obj-y) $(need-builtin)),)
80builtin-target := $(obj)/built-in.a
81endif
82
83modorder-target := $(obj)/modules.order
84
85# We keep a list of all modules in $(MODVERDIR)
86
87__build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
88 $(if $(KBUILD_MODULES),$(obj-m) $(modorder-target)) \
89 $(subdir-ym) $(always)
90 @:
91
92# Linus' kernel sanity checking tool
93ifneq ($(KBUILD_CHECKSRC),0)
94 ifeq ($(KBUILD_CHECKSRC),2)
95 quiet_cmd_force_checksrc = CHECK $<
96 cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
97 else
98 quiet_cmd_checksrc = CHECK $<
99 cmd_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
100 endif
101endif
102
103ifneq ($(KBUILD_ENABLE_EXTRA_GCC_CHECKS),)
104 cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $< ;
105endif
106
107# Do section mismatch analysis for each module/built-in.a
108ifdef CONFIG_DEBUG_SECTION_MISMATCH
109 cmd_secanalysis = ; scripts/mod/modpost $@
110endif
111
112# Compile C sources (.c)
113# ---------------------------------------------------------------------------
114
115# Default is built-in, unless we know otherwise
116modkern_cflags = \
117 $(if $(part-of-module), \
118 $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE), \
119 $(KBUILD_CFLAGS_KERNEL) $(CFLAGS_KERNEL))
120quiet_modtag := $(empty) $(empty)
121
122$(real-obj-m) : part-of-module := y
123$(real-obj-m:.o=.i) : part-of-module := y
124$(real-obj-m:.o=.s) : part-of-module := y
125$(real-obj-m:.o=.lst): part-of-module := y
126
127$(real-obj-m) : quiet_modtag := [M]
128$(real-obj-m:.o=.i) : quiet_modtag := [M]
129$(real-obj-m:.o=.s) : quiet_modtag := [M]
130$(real-obj-m:.o=.lst): quiet_modtag := [M]
131
132$(obj-m) : quiet_modtag := [M]
133
134quiet_cmd_cc_s_c = CC $(quiet_modtag) $@
135cmd_cc_s_c = $(CC) $(c_flags) $(DISABLE_LTO) -fverbose-asm -S -o $@ $<
136
137$(obj)/%.s: $(src)/%.c FORCE
138 $(call if_changed_dep,cc_s_c)
139
140quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
141cmd_cpp_i_c = $(CPP) $(c_flags) -o $@ $<
142
143$(obj)/%.i: $(src)/%.c FORCE
144 $(call if_changed_dep,cpp_i_c)
145
146# These mirror gensymtypes_S and co below, keep them in synch.
147cmd_gensymtypes_c = \
148 $(CPP) -D__GENKSYMS__ $(c_flags) $< | \
149 $(GENKSYMS) $(if $(1), -T $(2)) \
150 $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \
151 $(if $(KBUILD_PRESERVE),-p) \
152 -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
153
154quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
155cmd_cc_symtypes_c = \
156 set -e; \
157 $(call cmd_gensymtypes_c,true,$@) >/dev/null; \
158 test -s $@ || rm -f $@
159
160$(obj)/%.symtypes : $(src)/%.c FORCE
161 $(call cmd,cc_symtypes_c)
162
163# LLVM assembly
164# Generate .ll files from .c
165quiet_cmd_cc_ll_c = CC $(quiet_modtag) $@
166 cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $<
167
168$(obj)/%.ll: $(src)/%.c FORCE
169 $(call if_changed_dep,cc_ll_c)
170
171# C (.c) files
172# The C file is compiled and updated dependency information is generated.
173# (See cmd_cc_o_c + relevant part of rule_cc_o_c)
174
175quiet_cmd_cc_o_c = CC $(quiet_modtag) $@
176
177ifndef CONFIG_MODVERSIONS
178cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
179
180else
181# When module versioning is enabled the following steps are executed:
182# o compile a .tmp_<file>.o from <file>.c
183# o if .tmp_<file>.o doesn't contain a __ksymtab version, i.e. does
184# not export symbols, we just rename .tmp_<file>.o to <file>.o and
185# are done.
186# o otherwise, we calculate symbol versions using the good old
187# genksyms on the preprocessed source and postprocess them in a way
188# that they are usable as a linker script
189# o generate <file>.o from .tmp_<file>.o using the linker to
190# replace the unresolved symbols __crc_exported_symbol with
191# the actual value of the checksum generated by genksyms
192
193cmd_cc_o_c = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $<
194
195cmd_modversions_c = \
196 if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then \
197 $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
198 > $(@D)/.tmp_$(@F:.o=.ver); \
199 \
200 $(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) \
201 -T $(@D)/.tmp_$(@F:.o=.ver); \
202 rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver); \
203 else \
204 mv -f $(@D)/.tmp_$(@F) $@; \
205 fi;
206endif
207
208ifdef CONFIG_FTRACE_MCOUNT_RECORD
209# gcc 5 supports generating the mcount tables directly
210ifneq ($(call cc-option,-mrecord-mcount,y),y)
211KBUILD_CFLAGS += -mrecord-mcount
212else
213# else do it all manually
214ifdef BUILD_C_RECORDMCOUNT
215ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
216 RECORDMCOUNT_FLAGS = -w
217endif
218# Due to recursion, we must skip empty.o.
219# The empty.o file is created in the make process in order to determine
220# the target endianness and word size. It is made before all other C
221# files, including recordmcount.
222sub_cmd_record_mcount = \
223 if [ $(@) != "scripts/mod/empty.o" ]; then \
224 $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
225 fi;
226recordmcount_source := $(srctree)/scripts/recordmcount.c \
227 $(srctree)/scripts/recordmcount.h
228else
229sub_cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
230 "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
231 "$(if $(CONFIG_64BIT),64,32)" \
232 "$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CFLAGS)" \
233 "$(LD)" "$(NM)" "$(RM)" "$(MV)" \
234 "$(if $(part-of-module),1,0)" "$(@)";
235recordmcount_source := $(srctree)/scripts/recordmcount.pl
236endif # BUILD_C_RECORDMCOUNT
237cmd_record_mcount = \
238 if [ "$(findstring $(CC_FLAGS_FTRACE),$(_c_flags))" = \
239 "$(CC_FLAGS_FTRACE)" ]; then \
240 $(sub_cmd_record_mcount) \
241 fi;
242endif # -record-mcount
243endif # CONFIG_FTRACE_MCOUNT_RECORD
244
245ifdef CONFIG_STACK_VALIDATION
246ifneq ($(SKIP_STACK_VALIDATION),1)
247
248__objtool_obj := $(objtree)/tools/objtool/objtool
249
250objtool_args = $(if $(CONFIG_UNWINDER_ORC),orc generate,check)
251
252objtool_args += $(if $(part-of-module), --module,)
253
254ifndef CONFIG_FRAME_POINTER
255objtool_args += --no-fp
256endif
257ifdef CONFIG_GCOV_KERNEL
258objtool_args += --no-unreachable
259else
260objtool_args += $(call cc-ifversion, -lt, 0405, --no-unreachable)
261endif
262ifdef CONFIG_RETPOLINE
263ifneq ($(RETPOLINE_CFLAGS),)
264 objtool_args += --retpoline
265endif
266endif
267
268
269ifdef CONFIG_MODVERSIONS
270objtool_o = $(@D)/.tmp_$(@F)
271else
272objtool_o = $(@)
273endif
274
275# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
276# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
277# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
278cmd_objtool = $(if $(patsubst y%,, \
279 $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
280 $(__objtool_obj) $(objtool_args) "$(objtool_o)";)
281objtool_obj = $(if $(patsubst y%,, \
282 $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
283 $(__objtool_obj))
284
285endif # SKIP_STACK_VALIDATION
286endif # CONFIG_STACK_VALIDATION
287
288# Rebuild all objects when objtool changes, or is enabled/disabled.
289objtool_dep = $(objtool_obj) \
290 $(wildcard include/config/orc/unwinder.h \
291 include/config/stack/validation.h)
292
293define rule_cc_o_c
294 $(call echo-cmd,checksrc) $(cmd_checksrc) \
295 $(call cmd_and_fixdep,cc_o_c) \
296 $(cmd_checkdoc) \
297 $(call echo-cmd,objtool) $(cmd_objtool) \
298 $(cmd_modversions_c) \
299 $(call echo-cmd,record_mcount) $(cmd_record_mcount)
300endef
301
302define rule_as_o_S
303 $(call cmd_and_fixdep,as_o_S) \
304 $(call echo-cmd,objtool) $(cmd_objtool) \
305 $(cmd_modversions_S)
306endef
307
308# List module undefined symbols (or empty line if not enabled)
309ifdef CONFIG_TRIM_UNUSED_KSYMS
310cmd_undef_syms = $(NM) $@ | sed -n 's/^ *U //p' | xargs echo
311else
312cmd_undef_syms = echo
313endif
314
315# Built-in and composite module parts
316$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
317 $(call cmd,force_checksrc)
318 $(call if_changed_rule,cc_o_c)
319
320# Single-part modules are special since we need to mark them in $(MODVERDIR)
321
322$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
323 $(call cmd,force_checksrc)
324 $(call if_changed_rule,cc_o_c)
325 @{ echo $(@:.o=.ko); echo $@; \
326 $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
327
328quiet_cmd_cc_lst_c = MKLST $@
329 cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
330 $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
331 System.map $(OBJDUMP) > $@
332
333$(obj)/%.lst: $(src)/%.c FORCE
334 $(call if_changed_dep,cc_lst_c)
335
336# Compile assembler sources (.S)
337# ---------------------------------------------------------------------------
338
339modkern_aflags := $(KBUILD_AFLAGS_KERNEL) $(AFLAGS_KERNEL)
340
341$(real-obj-m) : modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
342$(real-obj-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
343
344# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
345# or a file that it includes, in order to get versioned symbols. We build a
346# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
347# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
348#
349# This is convoluted. The .S file must first be preprocessed to run guards and
350# expand names, then the resulting exports must be constructed into plain
351# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
352# to make the genksyms input.
353#
354# These mirror gensymtypes_c and co above, keep them in synch.
355cmd_gensymtypes_S = \
356 (echo "\#include <linux/kernel.h>" ; \
357 echo "\#include <asm/asm-prototypes.h>" ; \
358 $(CPP) $(a_flags) $< | \
359 grep "\<___EXPORT_SYMBOL\>" | \
360 sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ) | \
361 $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | \
362 $(GENKSYMS) $(if $(1), -T $(2)) \
363 $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \
364 $(if $(KBUILD_PRESERVE),-p) \
365 -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
366
367quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
368cmd_cc_symtypes_S = \
369 set -e; \
370 $(call cmd_gensymtypes_S,true,$@) >/dev/null; \
371 test -s $@ || rm -f $@
372
373$(obj)/%.symtypes : $(src)/%.S FORCE
374 $(call cmd,cc_symtypes_S)
375
376
377quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
378cmd_cpp_s_S = $(CPP) $(a_flags) -o $@ $<
379
380$(obj)/%.s: $(src)/%.S FORCE
381 $(call if_changed_dep,cpp_s_S)
382
383quiet_cmd_as_o_S = AS $(quiet_modtag) $@
384
385ifndef CONFIG_MODVERSIONS
386cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
387
388else
389
390ASM_PROTOTYPES := $(wildcard $(srctree)/arch/$(SRCARCH)/include/asm/asm-prototypes.h)
391
392ifeq ($(ASM_PROTOTYPES),)
393cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
394
395else
396
397# versioning matches the C process described above, with difference that
398# we parse asm-prototypes.h C header to get function definitions.
399
400cmd_as_o_S = $(CC) $(a_flags) -c -o $(@D)/.tmp_$(@F) $<
401
402cmd_modversions_S = \
403 if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then \
404 $(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
405 > $(@D)/.tmp_$(@F:.o=.ver); \
406 \
407 $(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) \
408 -T $(@D)/.tmp_$(@F:.o=.ver); \
409 rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver); \
410 else \
411 mv -f $(@D)/.tmp_$(@F) $@; \
412 fi;
413endif
414endif
415
416$(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE
417 $(call if_changed_rule,as_o_S)
418
419targets += $(filter-out $(subdir-obj-y), $(real-obj-y)) $(real-obj-m) $(lib-y)
420targets += $(extra-y) $(MAKECMDGOALS) $(always)
421
422# Linker scripts preprocessor (.lds.S -> .lds)
423# ---------------------------------------------------------------------------
424quiet_cmd_cpp_lds_S = LDS $@
425 cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
426 -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
427
428$(obj)/%.lds: $(src)/%.lds.S FORCE
429 $(call if_changed_dep,cpp_lds_S)
430
431# ASN.1 grammar
432# ---------------------------------------------------------------------------
433quiet_cmd_asn1_compiler = ASN.1 $@
434 cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
435 $(subst .h,.c,$@) $(subst .c,.h,$@)
436
437$(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
438 $(call cmd,asn1_compiler)
439
440# Build the compiled-in targets
441# ---------------------------------------------------------------------------
442
443# To build objects in subdirs, we need to descend into the directories
444$(sort $(subdir-obj-y)): $(subdir-ym) ;
445
446#
447# Rule to compile a set of .o files into one .o file
448#
449ifdef builtin-target
450
451# built-in.a archives are made with no symbol table or index which
452# makes them small and fast, but unable to be used by the linker.
453# scripts/link-vmlinux.sh builds an aggregate built-in.a with a symbol
454# table and index.
455quiet_cmd_ar_builtin = AR $@
456 cmd_ar_builtin = rm -f $@; \
457 $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(filter $(real-obj-y), $^)
458
459$(builtin-target): $(real-obj-y) FORCE
460 $(call if_changed,ar_builtin)
461
462targets += $(builtin-target)
463endif # builtin-target
464
465#
466# Rule to create modules.order file
467#
468# Create commands to either record .ko file or cat modules.order from
469# a subdirectory
470modorder-cmds = \
471 $(foreach m, $(modorder), \
472 $(if $(filter %/modules.order, $m), \
473 cat $m;, echo kernel/$m;))
474
475$(modorder-target): $(subdir-ym) FORCE
476 $(Q)(cat /dev/null; $(modorder-cmds)) > $@
477
478#
479# Rule to compile a set of .o files into one .a file
480#
481ifdef lib-target
482quiet_cmd_link_l_target = AR $@
483
484# lib target archives do get a symbol table and index
485cmd_link_l_target = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(lib-y)
486
487$(lib-target): $(lib-y) FORCE
488 $(call if_changed,link_l_target)
489
490targets += $(lib-target)
491
492dummy-object = $(obj)/.lib_exports.o
493ksyms-lds = $(dot-target).lds
494
495quiet_cmd_export_list = EXPORTS $@
496cmd_export_list = $(OBJDUMP) -h $< | \
497 sed -ne '/___ksymtab/s/.*+\([^ ]*\).*/EXTERN(\1)/p' >$(ksyms-lds);\
498 rm -f $(dummy-object);\
499 echo | $(CC) $(a_flags) -c -o $(dummy-object) -x assembler -;\
500 $(LD) $(ld_flags) -r -o $@ -T $(ksyms-lds) $(dummy-object);\
501 rm $(dummy-object) $(ksyms-lds)
502
503$(obj)/lib-ksyms.o: $(lib-target) FORCE
504 $(call if_changed,export_list)
505
506targets += $(obj)/lib-ksyms.o
507
508endif
509
510#
511# Rule to link composite objects
512#
513# Composite objects are specified in kbuild makefile as follows:
514# <composite-object>-objs := <list of .o files>
515# or
516# <composite-object>-y := <list of .o files>
517# or
518# <composite-object>-m := <list of .o files>
519# The -m syntax only works if <composite object> is a module
520link_multi_deps = \
521$(filter $(addprefix $(obj)/, \
522$($(subst $(obj)/,,$(@:.o=-objs))) \
523$($(subst $(obj)/,,$(@:.o=-y))) \
524$($(subst $(obj)/,,$(@:.o=-m)))), $^)
525
526quiet_cmd_link_multi-m = LD [M] $@
527cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis)
528
529$(multi-used-m): FORCE
530 $(call if_changed,link_multi-m)
531 @{ echo $(@:.o=.ko); echo $(link_multi_deps); \
532 $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
533$(call multi_depend, $(multi-used-m), .o, -objs -y -m)
534
535targets += $(multi-used-m)
536targets := $(filter-out $(PHONY), $(targets))
537
538# Add intermediate targets:
539# When building objects with specific suffix patterns, add intermediate
540# targets that the final targets are derived from.
541intermediate_targets = $(foreach sfx, $(2), \
542 $(patsubst %$(strip $(1)),%$(sfx), \
543 $(filter %$(strip $(1)), $(targets))))
544# %.asn1.o <- %.asn1.[ch] <- %.asn1
545# %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
546# %.lex.o <- %.lex.c <- %.l
547# %.tab.o <- %.tab.[ch] <- %.y
548targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
549 $(call intermediate_targets, .dtb.o, .dtb.S .dtb) \
550 $(call intermediate_targets, .lex.o, .lex.c) \
551 $(call intermediate_targets, .tab.o, .tab.c .tab.h)
552
553# Descending
554# ---------------------------------------------------------------------------
555
556PHONY += $(subdir-ym)
557$(subdir-ym):
558 $(Q)$(MAKE) $(build)=$@ need-builtin=$(if $(findstring $@,$(subdir-obj-y)),1)
559
560# Add FORCE to the prequisites of a target to force it to be always rebuilt.
561# ---------------------------------------------------------------------------
562
563PHONY += FORCE
564
565FORCE:
566
567# Read all saved command lines and dependencies for the $(targets) we
568# may be building above, using $(if_changed{,_dep}). As an
569# optimization, we don't need to read them if the target does not
570# exist, we will rebuild anyway in that case.
571
572cmd_files := $(wildcard $(foreach f,$(sort $(targets)),$(dir $(f)).$(notdir $(f)).cmd))
573
574ifneq ($(cmd_files),)
575 include $(cmd_files)
576endif
577
578ifneq ($(KBUILD_SRC),)
579# Create directories for object files if they do not exist
580obj-dirs := $(sort $(obj) $(patsubst %/,%, $(dir $(targets))))
581# If cmd_files exist, their directories apparently exist. Skip mkdir.
582exist-dirs := $(sort $(patsubst %/,%, $(dir $(cmd_files))))
583obj-dirs := $(strip $(filter-out $(exist-dirs), $(obj-dirs)))
584ifneq ($(obj-dirs),)
585$(shell mkdir -p $(obj-dirs))
586endif
587endif
588
589# Some files contained in $(targets) are intermediate artifacts.
590# We never want them to be removed automatically.
591.SECONDARY: $(targets)
592
593.PHONY: $(PHONY)