xref: /openbmc/linux/scripts/Makefile.build (revision e2c75e76) 
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
76obj-y += $(obj)/lib-ksyms.o
77endif
78
79ifneq ($(strip $(obj-y) $(need-builtin)),)
80builtin-target := $(obj)/built-in.o
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.o
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-objs-m)        : part-of-module := y
123$(real-objs-m:.o=.i)  : part-of-module := y
124$(real-objs-m:.o=.s)  : part-of-module := y
125$(real-objs-m:.o=.lst): part-of-module := y
126
127$(real-objs-m)        : quiet_modtag := [M]
128$(real-objs-m:.o=.i)  : quiet_modtag := [M]
129$(real-objs-m:.o=.s)  : quiet_modtag := [M]
130$(real-objs-m:.o=.lst): quiet_modtag := [M]
131
132$(obj-m)              : quiet_modtag := [M]
133
134# Default for not multi-part modules
135modname = $(basetarget)
136
137$(multi-objs-m)         : modname = $(modname-multi)
138$(multi-objs-m:.o=.i)   : modname = $(modname-multi)
139$(multi-objs-m:.o=.s)   : modname = $(modname-multi)
140$(multi-objs-m:.o=.lst) : modname = $(modname-multi)
141$(multi-objs-y)         : modname = $(modname-multi)
142$(multi-objs-y:.o=.i)   : modname = $(modname-multi)
143$(multi-objs-y:.o=.s)   : modname = $(modname-multi)
144$(multi-objs-y:.o=.lst) : modname = $(modname-multi)
145
146quiet_cmd_cc_s_c = CC $(quiet_modtag)  $@
147cmd_cc_s_c       = $(CC) $(c_flags) $(DISABLE_LTO) -fverbose-asm -S -o $@ $<
148
149$(obj)/%.s: $(src)/%.c FORCE
150	$(call if_changed_dep,cc_s_c)
151
152quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
153cmd_cpp_i_c       = $(CPP) $(c_flags) -o $@ $<
154
155$(obj)/%.i: $(src)/%.c FORCE
156	$(call if_changed_dep,cpp_i_c)
157
158# These mirror gensymtypes_S and co below, keep them in synch.
159cmd_gensymtypes_c =                                                         \
160    $(CPP) -D__GENKSYMS__ $(c_flags) $< |                                   \
161    $(GENKSYMS) $(if $(1), -T $(2))                                         \
162     $(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX))             \
163     $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS))                             \
164     $(if $(KBUILD_PRESERVE),-p)                                            \
165     -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
166
167quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
168cmd_cc_symtypes_c =                                                         \
169    set -e;                                                                 \
170    $(call cmd_gensymtypes_c,true,$@) >/dev/null;                           \
171    test -s $@ || rm -f $@
172
173$(obj)/%.symtypes : $(src)/%.c FORCE
174	$(call cmd,cc_symtypes_c)
175
176# LLVM assembly
177# Generate .ll files from .c
178quiet_cmd_cc_ll_c = CC $(quiet_modtag)  $@
179      cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $<
180
181$(obj)/%.ll: $(src)/%.c FORCE
182	$(call if_changed_dep,cc_ll_c)
183
184# C (.c) files
185# The C file is compiled and updated dependency information is generated.
186# (See cmd_cc_o_c + relevant part of rule_cc_o_c)
187
188quiet_cmd_cc_o_c = CC $(quiet_modtag)  $@
189
190ifndef CONFIG_MODVERSIONS
191cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
192
193else
194# When module versioning is enabled the following steps are executed:
195# o compile a .tmp_<file>.o from <file>.c
196# o if .tmp_<file>.o doesn't contain a __ksymtab version, i.e. does
197#   not export symbols, we just rename .tmp_<file>.o to <file>.o and
198#   are done.
199# o otherwise, we calculate symbol versions using the good old
200#   genksyms on the preprocessed source and postprocess them in a way
201#   that they are usable as a linker script
202# o generate <file>.o from .tmp_<file>.o using the linker to
203#   replace the unresolved symbols __crc_exported_symbol with
204#   the actual value of the checksum generated by genksyms
205
206cmd_cc_o_c = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $<
207
208cmd_modversions_c =								\
209	if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then		\
210		$(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
211		    > $(@D)/.tmp_$(@F:.o=.ver);					\
212										\
213		$(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) 			\
214			-T $(@D)/.tmp_$(@F:.o=.ver);				\
215		rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver);		\
216	else									\
217		mv -f $(@D)/.tmp_$(@F) $@;					\
218	fi;
219endif
220
221ifdef CONFIG_FTRACE_MCOUNT_RECORD
222ifdef BUILD_C_RECORDMCOUNT
223ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
224  RECORDMCOUNT_FLAGS = -w
225endif
226# Due to recursion, we must skip empty.o.
227# The empty.o file is created in the make process in order to determine
228# the target endianness and word size. It is made before all other C
229# files, including recordmcount.
230sub_cmd_record_mcount =					\
231	if [ $(@) != "scripts/mod/empty.o" ]; then	\
232		$(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)";	\
233	fi;
234recordmcount_source := $(srctree)/scripts/recordmcount.c \
235		    $(srctree)/scripts/recordmcount.h
236else
237sub_cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
238	"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
239	"$(if $(CONFIG_64BIT),64,32)" \
240	"$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CFLAGS)" \
241	"$(LD)" "$(NM)" "$(RM)" "$(MV)" \
242	"$(if $(part-of-module),1,0)" "$(@)";
243recordmcount_source := $(srctree)/scripts/recordmcount.pl
244endif # BUILD_C_RECORDMCOUNT
245cmd_record_mcount =						\
246	if [ "$(findstring $(CC_FLAGS_FTRACE),$(_c_flags))" =	\
247	     "$(CC_FLAGS_FTRACE)" ]; then			\
248		$(sub_cmd_record_mcount)			\
249	fi;
250endif # CONFIG_FTRACE_MCOUNT_RECORD
251
252ifdef CONFIG_STACK_VALIDATION
253ifneq ($(SKIP_STACK_VALIDATION),1)
254
255__objtool_obj := $(objtree)/tools/objtool/objtool
256
257objtool_args = $(if $(CONFIG_UNWINDER_ORC),orc generate,check)
258
259objtool_args += $(if $(part-of-module), --module,)
260
261ifndef CONFIG_FRAME_POINTER
262objtool_args += --no-fp
263endif
264ifdef CONFIG_GCOV_KERNEL
265objtool_args += --no-unreachable
266else
267objtool_args += $(call cc-ifversion, -lt, 0405, --no-unreachable)
268endif
269ifdef CONFIG_RETPOLINE
270ifneq ($(RETPOLINE_CFLAGS),)
271  objtool_args += --retpoline
272endif
273endif
274
275
276ifdef CONFIG_MODVERSIONS
277objtool_o = $(@D)/.tmp_$(@F)
278else
279objtool_o = $(@)
280endif
281
282# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
283# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
284# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
285cmd_objtool = $(if $(patsubst y%,, \
286	$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
287	$(__objtool_obj) $(objtool_args) "$(objtool_o)";)
288objtool_obj = $(if $(patsubst y%,, \
289	$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
290	$(__objtool_obj))
291
292endif # SKIP_STACK_VALIDATION
293endif # CONFIG_STACK_VALIDATION
294
295# Rebuild all objects when objtool changes, or is enabled/disabled.
296objtool_dep = $(objtool_obj)					\
297	      $(wildcard include/config/orc/unwinder.h		\
298			 include/config/stack/validation.h)
299
300define rule_cc_o_c
301	$(call echo-cmd,checksrc) $(cmd_checksrc)			  \
302	$(call cmd_and_fixdep,cc_o_c)					  \
303	$(cmd_checkdoc)							  \
304	$(call echo-cmd,objtool) $(cmd_objtool)				  \
305	$(cmd_modversions_c)						  \
306	$(call echo-cmd,record_mcount) $(cmd_record_mcount)
307endef
308
309define rule_as_o_S
310	$(call cmd_and_fixdep,as_o_S)					  \
311	$(call echo-cmd,objtool) $(cmd_objtool)				  \
312	$(cmd_modversions_S)
313endef
314
315# List module undefined symbols (or empty line if not enabled)
316ifdef CONFIG_TRIM_UNUSED_KSYMS
317cmd_undef_syms = $(NM) $@ | sed -n 's/^ \+U //p' | xargs echo
318else
319cmd_undef_syms = echo
320endif
321
322# Built-in and composite module parts
323$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
324	$(call cmd,force_checksrc)
325	$(call if_changed_rule,cc_o_c)
326
327# Single-part modules are special since we need to mark them in $(MODVERDIR)
328
329$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
330	$(call cmd,force_checksrc)
331	$(call if_changed_rule,cc_o_c)
332	@{ echo $(@:.o=.ko); echo $@; \
333	   $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
334
335quiet_cmd_cc_lst_c = MKLST   $@
336      cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
337		     $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
338				     System.map $(OBJDUMP) > $@
339
340$(obj)/%.lst: $(src)/%.c FORCE
341	$(call if_changed_dep,cc_lst_c)
342
343# Compile assembler sources (.S)
344# ---------------------------------------------------------------------------
345
346modkern_aflags := $(KBUILD_AFLAGS_KERNEL) $(AFLAGS_KERNEL)
347
348$(real-objs-m)      : modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
349$(real-objs-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
350
351# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
352# or a file that it includes, in order to get versioned symbols. We build a
353# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
354# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
355#
356# This is convoluted. The .S file must first be preprocessed to run guards and
357# expand names, then the resulting exports must be constructed into plain
358# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
359# to make the genksyms input.
360#
361# These mirror gensymtypes_c and co above, keep them in synch.
362cmd_gensymtypes_S =                                                         \
363    (echo "\#include <linux/kernel.h>" ;                                    \
364     echo "\#include <asm/asm-prototypes.h>" ;                              \
365    $(CPP) $(a_flags) $< |                                                  \
366     grep "\<___EXPORT_SYMBOL\>" |                                          \
367     sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ) | \
368    $(CPP) -D__GENKSYMS__ $(c_flags) -xc - |                                \
369    $(GENKSYMS) $(if $(1), -T $(2))                                         \
370     $(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX))             \
371     $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS))                             \
372     $(if $(KBUILD_PRESERVE),-p)                                            \
373     -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
374
375quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
376cmd_cc_symtypes_S =                                                         \
377    set -e;                                                                 \
378    $(call cmd_gensymtypes_S,true,$@) >/dev/null;                           \
379    test -s $@ || rm -f $@
380
381$(obj)/%.symtypes : $(src)/%.S FORCE
382	$(call cmd,cc_symtypes_S)
383
384
385quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
386cmd_cpp_s_S       = $(CPP) $(a_flags) -o $@ $<
387
388$(obj)/%.s: $(src)/%.S FORCE
389	$(call if_changed_dep,cpp_s_S)
390
391quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
392
393ifndef CONFIG_MODVERSIONS
394cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
395
396else
397
398ASM_PROTOTYPES := $(wildcard $(srctree)/arch/$(SRCARCH)/include/asm/asm-prototypes.h)
399
400ifeq ($(ASM_PROTOTYPES),)
401cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
402
403else
404
405# versioning matches the C process described above, with difference that
406# we parse asm-prototypes.h C header to get function definitions.
407
408cmd_as_o_S = $(CC) $(a_flags) -c -o $(@D)/.tmp_$(@F) $<
409
410cmd_modversions_S =								\
411	if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then		\
412		$(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
413		    > $(@D)/.tmp_$(@F:.o=.ver);					\
414										\
415		$(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) 			\
416			-T $(@D)/.tmp_$(@F:.o=.ver);				\
417		rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver);		\
418	else									\
419		mv -f $(@D)/.tmp_$(@F) $@;					\
420	fi;
421endif
422endif
423
424$(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE
425	$(call if_changed_rule,as_o_S)
426
427targets += $(real-objs-y) $(real-objs-m) $(lib-y)
428targets += $(extra-y) $(MAKECMDGOALS) $(always)
429
430# Linker scripts preprocessor (.lds.S -> .lds)
431# ---------------------------------------------------------------------------
432quiet_cmd_cpp_lds_S = LDS     $@
433      cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
434	                     -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
435
436$(obj)/%.lds: $(src)/%.lds.S FORCE
437	$(call if_changed_dep,cpp_lds_S)
438
439# ASN.1 grammar
440# ---------------------------------------------------------------------------
441quiet_cmd_asn1_compiler = ASN.1   $@
442      cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
443				$(subst .h,.c,$@) $(subst .c,.h,$@)
444
445.PRECIOUS: $(objtree)/$(obj)/%-asn1.c $(objtree)/$(obj)/%-asn1.h
446
447$(obj)/%-asn1.c $(obj)/%-asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
448	$(call cmd,asn1_compiler)
449
450# Build the compiled-in targets
451# ---------------------------------------------------------------------------
452
453# To build objects in subdirs, we need to descend into the directories
454$(sort $(subdir-obj-y)): $(subdir-ym) ;
455
456#
457# Rule to compile a set of .o files into one .o file
458#
459ifdef builtin-target
460
461ifdef CONFIG_THIN_ARCHIVES
462  cmd_make_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS)
463  cmd_make_empty_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS)
464  quiet_cmd_link_o_target = AR      $@
465else
466  cmd_make_builtin = $(LD) $(ld_flags) -r -o
467  cmd_make_empty_builtin = rm -f $@; $(AR) rcs$(KBUILD_ARFLAGS)
468  quiet_cmd_link_o_target = LD      $@
469endif
470
471# If the list of objects to link is empty, just create an empty built-in.o
472cmd_link_o_target = $(if $(strip $(obj-y)),\
473		      $(cmd_make_builtin) $@ $(filter $(obj-y), $^) \
474		      $(cmd_secanalysis),\
475		      $(cmd_make_empty_builtin) $@)
476
477$(builtin-target): $(obj-y) FORCE
478	$(call if_changed,link_o_target)
479
480targets += $(builtin-target)
481endif # builtin-target
482
483#
484# Rule to create modules.order file
485#
486# Create commands to either record .ko file or cat modules.order from
487# a subdirectory
488modorder-cmds =						\
489	$(foreach m, $(modorder),			\
490		$(if $(filter %/modules.order, $m),	\
491			cat $m;, echo kernel/$m;))
492
493$(modorder-target): $(subdir-ym) FORCE
494	$(Q)(cat /dev/null; $(modorder-cmds)) > $@
495
496#
497# Rule to compile a set of .o files into one .a file
498#
499ifdef lib-target
500quiet_cmd_link_l_target = AR      $@
501
502ifdef CONFIG_THIN_ARCHIVES
503  cmd_link_l_target = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(lib-y)
504else
505  cmd_link_l_target = rm -f $@; $(AR) rcs$(KBUILD_ARFLAGS) $@ $(lib-y)
506endif
507
508$(lib-target): $(lib-y) FORCE
509	$(call if_changed,link_l_target)
510
511targets += $(lib-target)
512
513dummy-object = $(obj)/.lib_exports.o
514ksyms-lds = $(dot-target).lds
515ifdef CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
516ref_prefix = EXTERN(_
517else
518ref_prefix = EXTERN(
519endif
520
521quiet_cmd_export_list = EXPORTS $@
522cmd_export_list = $(OBJDUMP) -h $< | \
523	sed -ne '/___ksymtab/s/.*+\([^ ]*\).*/$(ref_prefix)\1)/p' >$(ksyms-lds);\
524	rm -f $(dummy-object);\
525	echo | $(CC) $(a_flags) -c -o $(dummy-object) -x assembler -;\
526	$(LD) $(ld_flags) -r -o $@ -T $(ksyms-lds) $(dummy-object);\
527	rm $(dummy-object) $(ksyms-lds)
528
529$(obj)/lib-ksyms.o: $(lib-target) FORCE
530	$(call if_changed,export_list)
531
532targets += $(obj)/lib-ksyms.o
533
534endif
535
536#
537# Rule to link composite objects
538#
539#  Composite objects are specified in kbuild makefile as follows:
540#    <composite-object>-objs := <list of .o files>
541#  or
542#    <composite-object>-y    := <list of .o files>
543#  or
544#    <composite-object>-m    := <list of .o files>
545#  The -m syntax only works if <composite object> is a module
546link_multi_deps =                     \
547$(filter $(addprefix $(obj)/,         \
548$($(subst $(obj)/,,$(@:.o=-objs)))    \
549$($(subst $(obj)/,,$(@:.o=-y)))       \
550$($(subst $(obj)/,,$(@:.o=-m)))), $^)
551
552cmd_link_multi-link = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis)
553
554ifdef CONFIG_THIN_ARCHIVES
555  quiet_cmd_link_multi-y = AR      $@
556  cmd_link_multi-y = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(link_multi_deps)
557else
558  quiet_cmd_link_multi-y = LD      $@
559  cmd_link_multi-y = $(cmd_link_multi-link)
560endif
561
562quiet_cmd_link_multi-m = LD [M]  $@
563cmd_link_multi-m = $(cmd_link_multi-link)
564
565$(multi-used-y): FORCE
566	$(call if_changed,link_multi-y)
567$(call multi_depend, $(multi-used-y), .o, -objs -y)
568
569$(multi-used-m): FORCE
570	$(call if_changed,link_multi-m)
571	@{ echo $(@:.o=.ko); echo $(link_multi_deps); \
572	   $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
573$(call multi_depend, $(multi-used-m), .o, -objs -y -m)
574
575targets += $(multi-used-y) $(multi-used-m)
576targets := $(filter-out $(PHONY), $(targets))
577
578# Descending
579# ---------------------------------------------------------------------------
580
581PHONY += $(subdir-ym)
582$(subdir-ym):
583	$(Q)$(MAKE) $(build)=$@ need-builtin=$(if $(findstring $@,$(subdir-obj-y)),1)
584
585# Add FORCE to the prequisites of a target to force it to be always rebuilt.
586# ---------------------------------------------------------------------------
587
588PHONY += FORCE
589
590FORCE:
591
592# Read all saved command lines and dependencies for the $(targets) we
593# may be building above, using $(if_changed{,_dep}). As an
594# optimization, we don't need to read them if the target does not
595# exist, we will rebuild anyway in that case.
596
597cmd_files := $(wildcard $(foreach f,$(sort $(targets)),$(dir $(f)).$(notdir $(f)).cmd))
598
599ifneq ($(cmd_files),)
600  include $(cmd_files)
601endif
602
603ifneq ($(KBUILD_SRC),)
604# Create directories for object files if they do not exist
605obj-dirs := $(sort $(obj) $(patsubst %/,%, $(dir $(targets))))
606# If cmd_files exist, their directories apparently exist.  Skip mkdir.
607exist-dirs := $(sort $(patsubst %/,%, $(dir $(cmd_files))))
608obj-dirs := $(strip $(filter-out $(exist-dirs), $(obj-dirs)))
609ifneq ($(obj-dirs),)
610$(shell mkdir -p $(obj-dirs))
611endif
612endif
613
614# Declare the contents of the .PHONY variable as phony.  We keep that
615# information in a variable se we can use it in if_changed and friends.
616
617.PHONY: $(PHONY)
618