xref: /linux/scripts/Makefile.build (revision 3a025e1d1c2ea42fa497c9c6b21c284e0f69e28b)
1# ==========================================================================
2# Building
3# ==========================================================================
4
5src := $(obj)
6
7PHONY := __build
8__build:
9
10# Init all relevant variables used in kbuild files so
11# 1) they have correct type
12# 2) they do not inherit any value from the environment
13obj-y :=
14obj-m :=
15lib-y :=
16lib-m :=
17always :=
18targets :=
19subdir-y :=
20subdir-m :=
21EXTRA_AFLAGS   :=
22EXTRA_CFLAGS   :=
23EXTRA_CPPFLAGS :=
24EXTRA_LDFLAGS  :=
25asflags-y  :=
26ccflags-y  :=
27cppflags-y :=
28ldflags-y  :=
29
30subdir-asflags-y :=
31subdir-ccflags-y :=
32
33# Read auto.conf if it exists, otherwise ignore
34-include include/config/auto.conf
35
36include scripts/Kbuild.include
37
38# For backward compatibility check that these variables do not change
39save-cflags := $(CFLAGS)
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 $(kbuild-file)
45
46# If the save-* variables changed error out
47ifeq ($(KBUILD_NOPEDANTIC),)
48        ifneq ("$(save-cflags)","$(CFLAGS)")
49                $(error CFLAGS was changed in "$(kbuild-file)". Fix it to use ccflags-y)
50        endif
51endif
52
53include scripts/Makefile.lib
54
55ifdef host-progs
56ifneq ($(hostprogs-y),$(host-progs))
57$(warning kbuild: $(obj)/Makefile - Usage of host-progs is deprecated. Please replace with hostprogs-y!)
58hostprogs-y += $(host-progs)
59endif
60endif
61
62# Do not include host rules unless needed
63ifneq ($(hostprogs-y)$(hostprogs-m)$(hostlibs-y)$(hostlibs-m)$(hostcxxlibs-y)$(hostcxxlibs-m),)
64include scripts/Makefile.host
65endif
66
67ifneq ($(KBUILD_SRC),)
68# Create output directory if not already present
69_dummy := $(shell [ -d $(obj) ] || mkdir -p $(obj))
70
71# Create directories for object files if directory does not exist
72# Needed when obj-y := dir/file.o syntax is used
73_dummy := $(foreach d,$(obj-dirs), $(shell [ -d $(d) ] || mkdir -p $(d)))
74endif
75
76ifndef obj
77$(warning kbuild: Makefile.build is included improperly)
78endif
79
80# ===========================================================================
81
82ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
83lib-target := $(obj)/lib.a
84obj-y += $(obj)/lib-ksyms.o
85endif
86
87ifneq ($(strip $(obj-y) $(obj-m) $(obj-) $(subdir-m) $(lib-target)),)
88builtin-target := $(obj)/built-in.o
89endif
90
91modorder-target := $(obj)/modules.order
92
93# We keep a list of all modules in $(MODVERDIR)
94
95__build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
96	 $(if $(KBUILD_MODULES),$(obj-m) $(modorder-target)) \
97	 $(subdir-ym) $(always)
98	@:
99
100# Linus' kernel sanity checking tool
101ifneq ($(KBUILD_CHECKSRC),0)
102  ifeq ($(KBUILD_CHECKSRC),2)
103    quiet_cmd_force_checksrc = CHECK   $<
104          cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
105  else
106      quiet_cmd_checksrc     = CHECK   $<
107            cmd_checksrc     = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
108  endif
109endif
110
111ifneq ($(KBUILD_ENABLE_EXTRA_GCC_CHECKS),)
112  cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $< ;
113endif
114
115# Do section mismatch analysis for each module/built-in.o
116ifdef CONFIG_DEBUG_SECTION_MISMATCH
117  cmd_secanalysis = ; scripts/mod/modpost $@
118endif
119
120# Compile C sources (.c)
121# ---------------------------------------------------------------------------
122
123# Default is built-in, unless we know otherwise
124modkern_cflags =                                          \
125	$(if $(part-of-module),                           \
126		$(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE), \
127		$(KBUILD_CFLAGS_KERNEL) $(CFLAGS_KERNEL))
128quiet_modtag := $(empty)   $(empty)
129
130$(real-objs-m)        : part-of-module := y
131$(real-objs-m:.o=.i)  : part-of-module := y
132$(real-objs-m:.o=.s)  : part-of-module := y
133$(real-objs-m:.o=.lst): part-of-module := y
134
135$(real-objs-m)        : quiet_modtag := [M]
136$(real-objs-m:.o=.i)  : quiet_modtag := [M]
137$(real-objs-m:.o=.s)  : quiet_modtag := [M]
138$(real-objs-m:.o=.lst): quiet_modtag := [M]
139
140$(obj-m)              : quiet_modtag := [M]
141
142# Default for not multi-part modules
143modname = $(basetarget)
144
145$(multi-objs-m)         : modname = $(modname-multi)
146$(multi-objs-m:.o=.i)   : modname = $(modname-multi)
147$(multi-objs-m:.o=.s)   : modname = $(modname-multi)
148$(multi-objs-m:.o=.lst) : modname = $(modname-multi)
149$(multi-objs-y)         : modname = $(modname-multi)
150$(multi-objs-y:.o=.i)   : modname = $(modname-multi)
151$(multi-objs-y:.o=.s)   : modname = $(modname-multi)
152$(multi-objs-y:.o=.lst) : modname = $(modname-multi)
153
154quiet_cmd_cc_s_c = CC $(quiet_modtag)  $@
155cmd_cc_s_c       = $(CC) $(c_flags) $(DISABLE_LTO) -fverbose-asm -S -o $@ $<
156
157$(obj)/%.s: $(src)/%.c FORCE
158	$(call if_changed_dep,cc_s_c)
159
160quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
161cmd_cpp_i_c       = $(CPP) $(c_flags) -o $@ $<
162
163$(obj)/%.i: $(src)/%.c FORCE
164	$(call if_changed_dep,cpp_i_c)
165
166# These mirror gensymtypes_S and co below, keep them in synch.
167cmd_gensymtypes_c =                                                         \
168    $(CPP) -D__GENKSYMS__ $(c_flags) $< |                                   \
169    $(GENKSYMS) $(if $(1), -T $(2))                                         \
170     $(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX))             \
171     $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS))                             \
172     $(if $(KBUILD_PRESERVE),-p)                                            \
173     -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
174
175quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
176cmd_cc_symtypes_c =                                                         \
177    set -e;                                                                 \
178    $(call cmd_gensymtypes_c,true,$@) >/dev/null;                           \
179    test -s $@ || rm -f $@
180
181$(obj)/%.symtypes : $(src)/%.c FORCE
182	$(call cmd,cc_symtypes_c)
183
184# LLVM assembly
185# Generate .ll files from .c
186quiet_cmd_cc_ll_c = CC $(quiet_modtag)  $@
187      cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $<
188
189$(obj)/%.ll: $(src)/%.c FORCE
190	$(call if_changed_dep,cc_ll_c)
191
192# C (.c) files
193# The C file is compiled and updated dependency information is generated.
194# (See cmd_cc_o_c + relevant part of rule_cc_o_c)
195
196quiet_cmd_cc_o_c = CC $(quiet_modtag)  $@
197
198ifndef CONFIG_MODVERSIONS
199cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
200
201else
202# When module versioning is enabled the following steps are executed:
203# o compile a .tmp_<file>.o from <file>.c
204# o if .tmp_<file>.o doesn't contain a __ksymtab version, i.e. does
205#   not export symbols, we just rename .tmp_<file>.o to <file>.o and
206#   are done.
207# o otherwise, we calculate symbol versions using the good old
208#   genksyms on the preprocessed source and postprocess them in a way
209#   that they are usable as a linker script
210# o generate <file>.o from .tmp_<file>.o using the linker to
211#   replace the unresolved symbols __crc_exported_symbol with
212#   the actual value of the checksum generated by genksyms
213
214cmd_cc_o_c = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $<
215
216cmd_modversions_c =								\
217	if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then		\
218		$(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
219		    > $(@D)/.tmp_$(@F:.o=.ver);					\
220										\
221		$(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) 			\
222			-T $(@D)/.tmp_$(@F:.o=.ver);				\
223		rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver);		\
224	else									\
225		mv -f $(@D)/.tmp_$(@F) $@;					\
226	fi;
227endif
228
229ifdef CONFIG_FTRACE_MCOUNT_RECORD
230ifdef BUILD_C_RECORDMCOUNT
231ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
232  RECORDMCOUNT_FLAGS = -w
233endif
234# Due to recursion, we must skip empty.o.
235# The empty.o file is created in the make process in order to determine
236# the target endianness and word size. It is made before all other C
237# files, including recordmcount.
238sub_cmd_record_mcount =					\
239	if [ $(@) != "scripts/mod/empty.o" ]; then	\
240		$(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)";	\
241	fi;
242recordmcount_source := $(srctree)/scripts/recordmcount.c \
243		    $(srctree)/scripts/recordmcount.h
244else
245sub_cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
246	"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
247	"$(if $(CONFIG_64BIT),64,32)" \
248	"$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CFLAGS)" \
249	"$(LD)" "$(NM)" "$(RM)" "$(MV)" \
250	"$(if $(part-of-module),1,0)" "$(@)";
251recordmcount_source := $(srctree)/scripts/recordmcount.pl
252endif # BUILD_C_RECORDMCOUNT
253cmd_record_mcount =						\
254	if [ "$(findstring $(CC_FLAGS_FTRACE),$(_c_flags))" =	\
255	     "$(CC_FLAGS_FTRACE)" ]; then			\
256		$(sub_cmd_record_mcount)			\
257	fi;
258endif # CONFIG_FTRACE_MCOUNT_RECORD
259
260ifdef CONFIG_STACK_VALIDATION
261ifneq ($(SKIP_STACK_VALIDATION),1)
262
263__objtool_obj := $(objtree)/tools/objtool/objtool
264
265objtool_args = $(if $(CONFIG_ORC_UNWINDER),orc generate,check)
266
267ifndef CONFIG_FRAME_POINTER
268objtool_args += --no-fp
269endif
270ifdef CONFIG_GCOV_KERNEL
271objtool_args += --no-unreachable
272endif
273
274# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
275# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
276# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
277cmd_objtool = $(if $(patsubst y%,, \
278	$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
279	$(__objtool_obj) $(objtool_args) "$(@)";)
280objtool_obj = $(if $(patsubst y%,, \
281	$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
282	$(__objtool_obj))
283
284endif # SKIP_STACK_VALIDATION
285endif # CONFIG_STACK_VALIDATION
286
287# Rebuild all objects when objtool changes, or is enabled/disabled.
288objtool_dep = $(objtool_obj)					\
289	      $(wildcard include/config/orc/unwinder.h		\
290			 include/config/stack/validation.h)
291
292define rule_cc_o_c
293	$(call echo-cmd,checksrc) $(cmd_checksrc)			  \
294	$(call cmd_and_fixdep,cc_o_c)					  \
295	$(cmd_modversions_c)						  \
296	$(cmd_checkdoc)							  \
297	$(call echo-cmd,objtool) $(cmd_objtool)				  \
298	$(call echo-cmd,record_mcount) $(cmd_record_mcount)
299endef
300
301define rule_as_o_S
302	$(call cmd_and_fixdep,as_o_S)					  \
303	$(cmd_modversions_S)						  \
304	$(call echo-cmd,objtool) $(cmd_objtool)
305endef
306
307# List module undefined symbols (or empty line if not enabled)
308ifdef CONFIG_TRIM_UNUSED_KSYMS
309cmd_undef_syms = $(NM) $@ | sed -n 's/^ \+U //p' | xargs echo
310else
311cmd_undef_syms = echo
312endif
313
314# Built-in and composite module parts
315$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
316	$(call cmd,force_checksrc)
317	$(call if_changed_rule,cc_o_c)
318
319# Single-part modules are special since we need to mark them in $(MODVERDIR)
320
321$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
322	$(call cmd,force_checksrc)
323	$(call if_changed_rule,cc_o_c)
324	@{ echo $(@:.o=.ko); echo $@; \
325	   $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
326
327quiet_cmd_cc_lst_c = MKLST   $@
328      cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
329		     $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
330				     System.map $(OBJDUMP) > $@
331
332$(obj)/%.lst: $(src)/%.c FORCE
333	$(call if_changed_dep,cc_lst_c)
334
335# Compile assembler sources (.S)
336# ---------------------------------------------------------------------------
337
338modkern_aflags := $(KBUILD_AFLAGS_KERNEL) $(AFLAGS_KERNEL)
339
340$(real-objs-m)      : modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
341$(real-objs-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
342
343# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
344# or a file that it includes, in order to get versioned symbols. We build a
345# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
346# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
347#
348# This is convoluted. The .S file must first be preprocessed to run guards and
349# expand names, then the resulting exports must be constructed into plain
350# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
351# to make the genksyms input.
352#
353# These mirror gensymtypes_c and co above, keep them in synch.
354cmd_gensymtypes_S =                                                         \
355    (echo "\#include <linux/kernel.h>" ;                                    \
356     echo "\#include <asm/asm-prototypes.h>" ;                              \
357    $(CPP) $(a_flags) $< |                                                  \
358     grep "\<___EXPORT_SYMBOL\>" |                                          \
359     sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ) | \
360    $(CPP) -D__GENKSYMS__ $(c_flags) -xc - |                                \
361    $(GENKSYMS) $(if $(1), -T $(2))                                         \
362     $(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX))             \
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 += $(real-objs-y) $(real-objs-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) $(cpp_flags) -P -C -U$(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.PRECIOUS: $(objtree)/$(obj)/%-asn1.c $(objtree)/$(obj)/%-asn1.h
438
439$(obj)/%-asn1.c $(obj)/%-asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
440	$(call cmd,asn1_compiler)
441
442# Build the compiled-in targets
443# ---------------------------------------------------------------------------
444
445# To build objects in subdirs, we need to descend into the directories
446$(sort $(subdir-obj-y)): $(subdir-ym) ;
447
448#
449# Rule to compile a set of .o files into one .o file
450#
451ifdef builtin-target
452
453ifdef CONFIG_THIN_ARCHIVES
454  cmd_make_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS)
455  cmd_make_empty_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS)
456  quiet_cmd_link_o_target = AR      $@
457else
458  cmd_make_builtin = $(LD) $(ld_flags) -r -o
459  cmd_make_empty_builtin = rm -f $@; $(AR) rcs$(KBUILD_ARFLAGS)
460  quiet_cmd_link_o_target = LD      $@
461endif
462
463# If the list of objects to link is empty, just create an empty built-in.o
464cmd_link_o_target = $(if $(strip $(obj-y)),\
465		      $(cmd_make_builtin) $@ $(filter $(obj-y), $^) \
466		      $(cmd_secanalysis),\
467		      $(cmd_make_empty_builtin) $@)
468
469$(builtin-target): $(obj-y) FORCE
470	$(call if_changed,link_o_target)
471
472targets += $(builtin-target)
473endif # builtin-target
474
475#
476# Rule to create modules.order file
477#
478# Create commands to either record .ko file or cat modules.order from
479# a subdirectory
480modorder-cmds =						\
481	$(foreach m, $(modorder),			\
482		$(if $(filter %/modules.order, $m),	\
483			cat $m;, echo kernel/$m;))
484
485$(modorder-target): $(subdir-ym) FORCE
486	$(Q)(cat /dev/null; $(modorder-cmds)) > $@
487
488#
489# Rule to compile a set of .o files into one .a file
490#
491ifdef lib-target
492quiet_cmd_link_l_target = AR      $@
493
494ifdef CONFIG_THIN_ARCHIVES
495  cmd_link_l_target = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(lib-y)
496else
497  cmd_link_l_target = rm -f $@; $(AR) rcs$(KBUILD_ARFLAGS) $@ $(lib-y)
498endif
499
500$(lib-target): $(lib-y) FORCE
501	$(call if_changed,link_l_target)
502
503targets += $(lib-target)
504
505dummy-object = $(obj)/.lib_exports.o
506ksyms-lds = $(dot-target).lds
507ifdef CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
508ref_prefix = EXTERN(_
509else
510ref_prefix = EXTERN(
511endif
512
513quiet_cmd_export_list = EXPORTS $@
514cmd_export_list = $(OBJDUMP) -h $< | \
515	sed -ne '/___ksymtab/s/.*+\([^ ]*\).*/$(ref_prefix)\1)/p' >$(ksyms-lds);\
516	rm -f $(dummy-object);\
517	echo | $(CC) $(a_flags) -c -o $(dummy-object) -x assembler -;\
518	$(LD) $(ld_flags) -r -o $@ -T $(ksyms-lds) $(dummy-object);\
519	rm $(dummy-object) $(ksyms-lds)
520
521$(obj)/lib-ksyms.o: $(lib-target) FORCE
522	$(call if_changed,export_list)
523
524targets += $(obj)/lib-ksyms.o
525
526endif
527
528#
529# Rule to link composite objects
530#
531#  Composite objects are specified in kbuild makefile as follows:
532#    <composite-object>-objs := <list of .o files>
533#  or
534#    <composite-object>-y    := <list of .o files>
535#  or
536#    <composite-object>-m    := <list of .o files>
537#  The -m syntax only works if <composite object> is a module
538link_multi_deps =                     \
539$(filter $(addprefix $(obj)/,         \
540$($(subst $(obj)/,,$(@:.o=-objs)))    \
541$($(subst $(obj)/,,$(@:.o=-y)))       \
542$($(subst $(obj)/,,$(@:.o=-m)))), $^)
543
544cmd_link_multi-link = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis)
545
546ifdef CONFIG_THIN_ARCHIVES
547  quiet_cmd_link_multi-y = AR      $@
548  cmd_link_multi-y = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(link_multi_deps)
549else
550  quiet_cmd_link_multi-y = LD      $@
551  cmd_link_multi-y = $(cmd_link_multi-link)
552endif
553
554quiet_cmd_link_multi-m = LD [M]  $@
555cmd_link_multi-m = $(cmd_link_multi-link)
556
557$(multi-used-y): FORCE
558	$(call if_changed,link_multi-y)
559$(call multi_depend, $(multi-used-y), .o, -objs -y)
560
561$(multi-used-m): FORCE
562	$(call if_changed,link_multi-m)
563	@{ echo $(@:.o=.ko); echo $(link_multi_deps); \
564	   $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
565$(call multi_depend, $(multi-used-m), .o, -objs -y -m)
566
567targets += $(multi-used-y) $(multi-used-m)
568
569
570# Descending
571# ---------------------------------------------------------------------------
572
573PHONY += $(subdir-ym)
574$(subdir-ym):
575	$(Q)$(MAKE) $(build)=$@
576
577# Add FORCE to the prequisites of a target to force it to be always rebuilt.
578# ---------------------------------------------------------------------------
579
580PHONY += FORCE
581
582FORCE:
583
584# Read all saved command lines and dependencies for the $(targets) we
585# may be building above, using $(if_changed{,_dep}). As an
586# optimization, we don't need to read them if the target does not
587# exist, we will rebuild anyway in that case.
588
589targets := $(wildcard $(sort $(targets)))
590cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))
591
592ifneq ($(cmd_files),)
593  include $(cmd_files)
594endif
595
596# Declare the contents of the .PHONY variable as phony.  We keep that
597# information in a variable se we can use it in if_changed and friends.
598
599.PHONY: $(PHONY)
600