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 := $(obj)/
9$(obj)/:
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 :=
29rustflags-y :=
30cppflags-y :=
31ldflags-y :=
32
33subdir-asflags-y :=
34subdir-ccflags-y :=
35
36# Read auto.conf if it exists, otherwise ignore
37-include include/config/auto.conf
38
39include $(srctree)/scripts/Kbuild.include
40include $(srctree)/scripts/Makefile.compiler
41include $(kbuild-file)
42include $(srctree)/scripts/Makefile.lib
43
44# Do not include hostprogs rules unless needed.
45# $(sort ...) is used here to remove duplicated words and excessive spaces.
46hostprogs := $(sort $(hostprogs))
47ifneq ($(hostprogs),)
48include $(srctree)/scripts/Makefile.host
49endif
50
51# Do not include userprogs rules unless needed.
52# $(sort ...) is used here to remove duplicated words and excessive spaces.
53userprogs := $(sort $(userprogs))
54ifneq ($(userprogs),)
55include $(srctree)/scripts/Makefile.userprogs
56endif
57
58ifndef obj
59$(warning kbuild: Makefile.build is included improperly)
60endif
61
62ifeq ($(need-modorder),)
63ifneq ($(obj-m),)
64$(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.)
65$(warning You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.)
66endif
67endif
68
69# ===========================================================================
70
71# subdir-builtin and subdir-modorder may contain duplications. Use $(sort ...)
72subdir-builtin := $(sort $(filter %/built-in.a, $(real-obj-y)))
73subdir-modorder := $(sort $(filter %/modules.order, $(obj-m)))
74
75targets-for-builtin := $(extra-y)
76
77ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
78targets-for-builtin += $(obj)/lib.a
79endif
80
81ifdef need-builtin
82targets-for-builtin += $(obj)/built-in.a
83endif
84
85targets-for-modules := $(foreach x, o mod, \
86 $(patsubst %.o, %.$x, $(filter %.o, $(obj-m))))
87
88ifdef need-modorder
89targets-for-modules += $(obj)/modules.order
90endif
91
92targets += $(targets-for-builtin) $(targets-for-modules)
93
94# Linus' kernel sanity checking tool
95ifeq ($(KBUILD_CHECKSRC),1)
96 quiet_cmd_checksrc = CHECK $<
97 cmd_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
98else ifeq ($(KBUILD_CHECKSRC),2)
99 quiet_cmd_force_checksrc = CHECK $<
100 cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
101endif
102
103ifneq ($(KBUILD_EXTRA_WARN),)
104 cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $(KDOCFLAGS) \
105 $(if $(findstring 2, $(KBUILD_EXTRA_WARN)), -Wall) \
106 $<
107endif
108
109# Compile C sources (.c)
110# ---------------------------------------------------------------------------
111
112quiet_cmd_cc_s_c = CC $(quiet_modtag) $@
113 cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS) $(CC_FLAGS_LTO), $(c_flags)) -fverbose-asm -S -o $@ $<
114
115$(obj)/%.s: $(src)/%.c FORCE
116 $(call if_changed_dep,cc_s_c)
117
118quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
119cmd_cpp_i_c = $(CPP) $(c_flags) -o $@ $<
120
121$(obj)/%.i: $(src)/%.c FORCE
122 $(call if_changed_dep,cpp_i_c)
123
124genksyms = scripts/genksyms/genksyms \
125 $(if $(1), -T $(2)) \
126 $(if $(KBUILD_PRESERVE), -p) \
127 -r $(or $(wildcard $(2:.symtypes=.symref)), /dev/null)
128
129# These mirror gensymtypes_S and co below, keep them in synch.
130cmd_gensymtypes_c = $(CPP) -D__GENKSYMS__ $(c_flags) $< | $(genksyms)
131
132quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
133 cmd_cc_symtypes_c = $(call cmd_gensymtypes_c,true,$@) >/dev/null
134
135$(obj)/%.symtypes : $(src)/%.c FORCE
136 $(call cmd,cc_symtypes_c)
137
138# LLVM assembly
139# Generate .ll files from .c
140quiet_cmd_cc_ll_c = CC $(quiet_modtag) $@
141 cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -fno-discard-value-names -o $@ $<
142
143$(obj)/%.ll: $(src)/%.c FORCE
144 $(call if_changed_dep,cc_ll_c)
145
146# C (.c) files
147# The C file is compiled and updated dependency information is generated.
148# (See cmd_cc_o_c + relevant part of rule_cc_o_c)
149
150is-single-obj-m = $(and $(part-of-module),$(filter $@, $(obj-m)),y)
151
152# When a module consists of a single object, there is no reason to keep LLVM IR.
153# Make $(LD) covert LLVM IR to ELF here.
154ifdef CONFIG_LTO_CLANG
155cmd_ld_single_m = $(if $(is-single-obj-m), ; $(LD) $(ld_flags) -r -o $(tmp-target) $@; mv $(tmp-target) $@)
156endif
157
158quiet_cmd_cc_o_c = CC $(quiet_modtag) $@
159 cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< \
160 $(cmd_ld_single_m) \
161 $(cmd_objtool)
162
163ifdef CONFIG_MODVERSIONS
164# When module versioning is enabled the following steps are executed:
165# o compile a <file>.o from <file>.c
166# o if <file>.o doesn't contain a __export_symbol_*, i.e. does
167# not export symbols, it's done.
168# o otherwise, we calculate symbol versions using the good old
169# genksyms on the preprocessed source and dump them into the .cmd file.
170# o modpost will extract versions from that file and create *.c files that will
171# be compiled and linked to the kernel and/or modules.
172
173gen_symversions = \
174 if $(NM) $@ 2>/dev/null | grep -q ' __export_symbol_'; then \
175 $(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
176 >> $(dot-target).cmd; \
177 fi
178
179cmd_gen_symversions_c = $(call gen_symversions,c)
180
181endif
182
183ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
184# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
185ifdef BUILD_C_RECORDMCOUNT
186ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
187 RECORDMCOUNT_FLAGS = -w
188endif
189# Due to recursion, we must skip empty.o.
190# The empty.o file is created in the make process in order to determine
191# the target endianness and word size. It is made before all other C
192# files, including recordmcount.
193sub_cmd_record_mcount = \
194 if [ $(@) != "scripts/mod/empty.o" ]; then \
195 $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
196 fi;
197recordmcount_source := $(srctree)/scripts/recordmcount.c \
198 $(srctree)/scripts/recordmcount.h
199else
200sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
201 "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
202 "$(if $(CONFIG_64BIT),64,32)" \
203 "$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
204 "$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
205 "$(if $(part-of-module),1,0)" "$(@)";
206recordmcount_source := $(srctree)/scripts/recordmcount.pl
207endif # BUILD_C_RECORDMCOUNT
208cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), \
209 $(sub_cmd_record_mcount))
210endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
211
212# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
213# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
214# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
215
216is-standard-object = $(if $(filter-out y%, $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y)
217
218$(obj)/%.o: objtool-enabled = $(if $(is-standard-object),$(if $(delay-objtool),$(is-single-obj-m),y))
219
220ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
221cmd_warn_shared_object = $(if $(word 2, $(modname-multi)),$(warning $(kbuild-file): $*.o is added to multiple modules: $(modname-multi)))
222endif
223
224define rule_cc_o_c
225 $(call cmd_and_fixdep,cc_o_c)
226 $(call cmd,checksrc)
227 $(call cmd,checkdoc)
228 $(call cmd,gen_objtooldep)
229 $(call cmd,gen_symversions_c)
230 $(call cmd,record_mcount)
231 $(call cmd,warn_shared_object)
232endef
233
234define rule_as_o_S
235 $(call cmd_and_fixdep,as_o_S)
236 $(call cmd,gen_objtooldep)
237 $(call cmd,gen_symversions_S)
238 $(call cmd,warn_shared_object)
239endef
240
241# Built-in and composite module parts
242$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
243 $(call if_changed_rule,cc_o_c)
244 $(call cmd,force_checksrc)
245
246# To make this rule robust against "Argument list too long" error,
247# ensure to add $(obj)/ prefix by a shell command.
248cmd_mod = printf '%s\n' $(call real-search, $*.o, .o, -objs -y -m) | \
249 $(AWK) '!x[$$0]++ { print("$(obj)/"$$0) }' > $@
250
251$(obj)/%.mod: FORCE
252 $(call if_changed,mod)
253
254quiet_cmd_cc_lst_c = MKLST $@
255 cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
256 $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
257 System.map $(OBJDUMP) > $@
258
259$(obj)/%.lst: $(src)/%.c FORCE
260 $(call if_changed_dep,cc_lst_c)
261
262# Compile Rust sources (.rs)
263# ---------------------------------------------------------------------------
264
265rust_allowed_features := new_uninit
266
267rust_common_cmd = \
268 RUST_MODFILE=$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \
269 -Zallow-features=$(rust_allowed_features) \
270 -Zcrate-attr=no_std \
271 -Zcrate-attr='feature($(rust_allowed_features))' \
272 --extern alloc --extern kernel \
273 --crate-type rlib -L $(objtree)/rust/ \
274 --crate-name $(basename $(notdir $@)) \
275 --emit=dep-info=$(depfile)
276
277# `--emit=obj`, `--emit=asm` and `--emit=llvm-ir` imply a single codegen unit
278# will be used. We explicitly request `-Ccodegen-units=1` in any case, and
279# the compiler shows a warning if it is not 1. However, if we ever stop
280# requesting it explicitly and we start using some other `--emit` that does not
281# imply it (and for which codegen is performed), then we would be out of sync,
282# i.e. the outputs we would get for the different single targets (e.g. `.ll`)
283# would not match each other.
284
285quiet_cmd_rustc_o_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
286 cmd_rustc_o_rs = $(rust_common_cmd) --emit=obj=$@ $<
287
288$(obj)/%.o: $(src)/%.rs FORCE
289 $(call if_changed_dep,rustc_o_rs)
290
291quiet_cmd_rustc_rsi_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
292 cmd_rustc_rsi_rs = \
293 $(rust_common_cmd) -Zunpretty=expanded $< >$@; \
294 command -v $(RUSTFMT) >/dev/null && $(RUSTFMT) $@
295
296$(obj)/%.rsi: $(src)/%.rs FORCE
297 $(call if_changed_dep,rustc_rsi_rs)
298
299quiet_cmd_rustc_s_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
300 cmd_rustc_s_rs = $(rust_common_cmd) --emit=asm=$@ $<
301
302$(obj)/%.s: $(src)/%.rs FORCE
303 $(call if_changed_dep,rustc_s_rs)
304
305quiet_cmd_rustc_ll_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
306 cmd_rustc_ll_rs = $(rust_common_cmd) --emit=llvm-ir=$@ $<
307
308$(obj)/%.ll: $(src)/%.rs FORCE
309 $(call if_changed_dep,rustc_ll_rs)
310
311# Compile assembler sources (.S)
312# ---------------------------------------------------------------------------
313
314# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
315# or a file that it includes, in order to get versioned symbols. We build a
316# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
317# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
318#
319# This is convoluted. The .S file must first be preprocessed to run guards and
320# expand names, then the resulting exports must be constructed into plain
321# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
322# to make the genksyms input.
323#
324# These mirror gensymtypes_c and co above, keep them in synch.
325cmd_gensymtypes_S = \
326 { echo "\#include <linux/kernel.h>" ; \
327 echo "\#include <asm/asm-prototypes.h>" ; \
328 $(NM) $@ | sed -n 's/.* __export_symbol_\(.*\)/EXPORT_SYMBOL(\1);/p' ; } | \
329 $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | $(genksyms)
330
331quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
332 cmd_cc_symtypes_S = $(call cmd_gensymtypes_S,true,$@) >/dev/null
333
334$(obj)/%.symtypes : $(src)/%.S FORCE
335 $(call cmd,cc_symtypes_S)
336
337
338quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
339cmd_cpp_s_S = $(CPP) $(a_flags) -o $@ $<
340
341$(obj)/%.s: $(src)/%.S FORCE
342 $(call if_changed_dep,cpp_s_S)
343
344quiet_cmd_as_o_S = AS $(quiet_modtag) $@
345 cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $< $(cmd_objtool)
346
347ifdef CONFIG_ASM_MODVERSIONS
348
349# versioning matches the C process described above, with difference that
350# we parse asm-prototypes.h C header to get function definitions.
351
352cmd_gen_symversions_S = $(call gen_symversions,S)
353
354endif
355
356$(obj)/%.o: $(src)/%.S FORCE
357 $(call if_changed_rule,as_o_S)
358
359targets += $(filter-out $(subdir-builtin), $(real-obj-y))
360targets += $(filter-out $(subdir-modorder), $(real-obj-m))
361targets += $(real-dtb-y) $(lib-y) $(always-y)
362
363# Linker scripts preprocessor (.lds.S -> .lds)
364# ---------------------------------------------------------------------------
365quiet_cmd_cpp_lds_S = LDS $@
366 cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
367 -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
368
369$(obj)/%.lds: $(src)/%.lds.S FORCE
370 $(call if_changed_dep,cpp_lds_S)
371
372# ASN.1 grammar
373# ---------------------------------------------------------------------------
374quiet_cmd_asn1_compiler = ASN.1 $(basename $@).[ch]
375 cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
376 $(basename $@).c $(basename $@).h
377
378$(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
379 $(call cmd,asn1_compiler)
380
381# Build the compiled-in targets
382# ---------------------------------------------------------------------------
383
384# To build objects in subdirs, we need to descend into the directories
385$(subdir-builtin): $(obj)/%/built-in.a: $(obj)/% ;
386$(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ;
387
388#
389# Rule to compile a set of .o files into one .a file (without symbol table)
390#
391# To make this rule robust against "Argument list too long" error,
392# remove $(obj)/ prefix, and restore it by a shell command.
393
394quiet_cmd_ar_builtin = AR $@
395 cmd_ar_builtin = rm -f $@; \
396 $(if $(real-prereqs), printf "$(obj)/%s " $(patsubst $(obj)/%,%,$(real-prereqs)) | xargs) \
397 $(AR) cDPrST $@
398
399$(obj)/built-in.a: $(real-obj-y) FORCE
400 $(call if_changed,ar_builtin)
401
402#
403# Rule to create modules.order file
404#
405# Create commands to either record .ko file or cat modules.order from
406# a subdirectory
407# Add $(obj-m) as the prerequisite to avoid updating the timestamp of
408# modules.order unless contained modules are updated.
409
410cmd_modules_order = { $(foreach m, $(real-prereqs), \
411 $(if $(filter %/modules.order, $m), cat $m, echo $m);) :; } \
412 > $@
413
414$(obj)/modules.order: $(obj-m) FORCE
415 $(call if_changed,modules_order)
416
417#
418# Rule to compile a set of .o files into one .a file (with symbol table)
419#
420
421$(obj)/lib.a: $(lib-y) FORCE
422 $(call if_changed,ar)
423
424quiet_cmd_ld_multi_m = LD [M] $@
425 cmd_ld_multi_m = $(LD) $(ld_flags) -r -o $@ @$(patsubst %.o,%.mod,$@) $(cmd_objtool)
426
427define rule_ld_multi_m
428 $(call cmd_and_savecmd,ld_multi_m)
429 $(call cmd,gen_objtooldep)
430endef
431
432$(multi-obj-m): objtool-enabled := $(delay-objtool)
433$(multi-obj-m): part-of-module := y
434$(multi-obj-m): %.o: %.mod FORCE
435 $(call if_changed_rule,ld_multi_m)
436$(call multi_depend, $(multi-obj-m), .o, -objs -y -m)
437
438# Add intermediate targets:
439# When building objects with specific suffix patterns, add intermediate
440# targets that the final targets are derived from.
441intermediate_targets = $(foreach sfx, $(2), \
442 $(patsubst %$(strip $(1)),%$(sfx), \
443 $(filter %$(strip $(1)), $(targets))))
444# %.asn1.o <- %.asn1.[ch] <- %.asn1
445# %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
446# %.dtbo.o <- %.dtbo.S <- %.dtbo <- %.dtso
447# %.lex.o <- %.lex.c <- %.l
448# %.tab.o <- %.tab.[ch] <- %.y
449targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
450 $(call intermediate_targets, .dtb.o, .dtb.S .dtb) \
451 $(call intermediate_targets, .dtbo.o, .dtbo.S .dtbo) \
452 $(call intermediate_targets, .lex.o, .lex.c) \
453 $(call intermediate_targets, .tab.o, .tab.c .tab.h)
454
455# Build
456# ---------------------------------------------------------------------------
457
458$(obj)/: $(if $(KBUILD_BUILTIN), $(targets-for-builtin)) \
459 $(if $(KBUILD_MODULES), $(targets-for-modules)) \
460 $(subdir-ym) $(always-y)
461 @:
462
463# Single targets
464# ---------------------------------------------------------------------------
465
466single-subdirs := $(foreach d, $(subdir-ym), $(if $(filter $d/%, $(MAKECMDGOALS)), $d))
467single-subdir-goals := $(filter $(addsuffix /%, $(single-subdirs)), $(MAKECMDGOALS))
468
469$(single-subdir-goals): $(single-subdirs)
470 @:
471
472# Descending
473# ---------------------------------------------------------------------------
474
475PHONY += $(subdir-ym)
476$(subdir-ym):
477 $(Q)$(MAKE) $(build)=$@ \
478 need-builtin=$(if $(filter $@/built-in.a, $(subdir-builtin)),1) \
479 need-modorder=$(if $(filter $@/modules.order, $(subdir-modorder)),1) \
480 $(filter $@/%, $(single-subdir-goals))
481
482# Add FORCE to the prequisites of a target to force it to be always rebuilt.
483# ---------------------------------------------------------------------------
484
485PHONY += FORCE
486
487FORCE:
488
489targets += $(filter-out $(single-subdir-goals), $(MAKECMDGOALS))
490targets := $(filter-out $(PHONY), $(targets))
491
492# Read all saved command lines and dependencies for the $(targets) we
493# may be building above, using $(if_changed{,_dep}). As an
494# optimization, we don't need to read them if the target does not
495# exist, we will rebuild anyway in that case.
496
497existing-targets := $(wildcard $(sort $(targets)))
498
499-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
500
501# Create directories for object files if they do not exist
502obj-dirs := $(sort $(patsubst %/,%, $(dir $(targets))))
503# If targets exist, their directories apparently exist. Skip mkdir.
504existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))
505obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))
506ifneq ($(obj-dirs),)
507$(shell mkdir -p $(obj-dirs))
508endif
509
510.PHONY: $(PHONY)