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 := $(if $(VPATH),$(VPATH)/)$(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)))
74subdir-dtbslist := $(sort $(filter %/dtbs-list, $(dtb-y)))
75
76targets-for-builtin := $(extra-y)
77
78ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
79targets-for-builtin += $(obj)/lib.a
80endif
81
82ifdef need-builtin
83targets-for-builtin += $(obj)/built-in.a
84endif
85
86targets-for-modules := $(foreach x, o mod, \
87 $(patsubst %.o, %.$x, $(filter %.o, $(obj-m))))
88
89ifdef need-modorder
90targets-for-modules += $(obj)/modules.order
91endif
92
93targets += $(targets-for-builtin) $(targets-for-modules)
94
95# Linus' kernel sanity checking tool
96ifeq ($(KBUILD_CHECKSRC),1)
97 quiet_cmd_checksrc = CHECK $<
98 cmd_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
99else ifeq ($(KBUILD_CHECKSRC),2)
100 quiet_cmd_force_checksrc = CHECK $<
101 cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
102endif
103
104ifneq ($(KBUILD_EXTRA_WARN),)
105 cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $(KDOCFLAGS) \
106 $(if $(findstring 2, $(KBUILD_EXTRA_WARN)), -Wall) \
107 $<
108endif
109
110# Compile C sources (.c)
111# ---------------------------------------------------------------------------
112
113quiet_cmd_cc_s_c = CC $(quiet_modtag) $@
114 cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS) $(CC_FLAGS_LTO), $(c_flags)) -fverbose-asm -S -o $@ $<
115
116$(obj)/%.s: $(obj)/%.c FORCE
117 $(call if_changed_dep,cc_s_c)
118
119quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
120cmd_cpp_i_c = $(CPP) $(c_flags) -o $@ $<
121
122$(obj)/%.i: $(obj)/%.c FORCE
123 $(call if_changed_dep,cpp_i_c)
124
125genksyms = scripts/genksyms/genksyms \
126 $(if $(1), -T $(2)) \
127 $(if $(KBUILD_PRESERVE), -p) \
128 -r $(or $(wildcard $(2:.symtypes=.symref)), /dev/null)
129
130# These mirror gensymtypes_S and co below, keep them in synch.
131cmd_gensymtypes_c = $(CPP) -D__GENKSYMS__ $(c_flags) $< | $(genksyms)
132
133quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
134 cmd_cc_symtypes_c = $(call cmd_gensymtypes_c,true,$@) >/dev/null
135
136$(obj)/%.symtypes : $(obj)/%.c FORCE
137 $(call cmd,cc_symtypes_c)
138
139# LLVM assembly
140# Generate .ll files from .c
141quiet_cmd_cc_ll_c = CC $(quiet_modtag) $@
142 cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -fno-discard-value-names -o $@ $<
143
144$(obj)/%.ll: $(obj)/%.c FORCE
145 $(call if_changed_dep,cc_ll_c)
146
147# C (.c) files
148# The C file is compiled and updated dependency information is generated.
149# (See cmd_cc_o_c + relevant part of rule_cc_o_c)
150
151is-single-obj-m = $(and $(part-of-module),$(filter $@, $(obj-m)),y)
152
153# When a module consists of a single object, there is no reason to keep LLVM IR.
154# Make $(LD) covert LLVM IR to ELF here.
155ifdef CONFIG_LTO_CLANG
156cmd_ld_single_m = $(if $(is-single-obj-m), ; $(LD) $(ld_flags) -r -o $(tmp-target) $@; mv $(tmp-target) $@)
157endif
158
159quiet_cmd_cc_o_c = CC $(quiet_modtag) $@
160 cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< \
161 $(cmd_ld_single_m) \
162 $(cmd_objtool)
163
164ifdef CONFIG_MODVERSIONS
165# When module versioning is enabled the following steps are executed:
166# o compile a <file>.o from <file>.c
167# o if <file>.o doesn't contain a __export_symbol_*, i.e. does
168# not export symbols, it's done.
169# o otherwise, we calculate symbol versions using the good old
170# genksyms on the preprocessed source and dump them into the .cmd file.
171# o modpost will extract versions from that file and create *.c files that will
172# be compiled and linked to the kernel and/or modules.
173
174gen_symversions = \
175 if $(NM) $@ 2>/dev/null | grep -q ' __export_symbol_'; then \
176 $(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
177 >> $(dot-target).cmd; \
178 fi
179
180cmd_gen_symversions_c = $(call gen_symversions,c)
181
182endif
183
184ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
185# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
186ifdef BUILD_C_RECORDMCOUNT
187ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
188 RECORDMCOUNT_FLAGS = -w
189endif
190# Due to recursion, we must skip empty.o.
191# The empty.o file is created in the make process in order to determine
192# the target endianness and word size. It is made before all other C
193# files, including recordmcount.
194sub_cmd_record_mcount = \
195 if [ $(@) != "scripts/mod/empty.o" ]; then \
196 $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
197 fi;
198recordmcount_source := $(srctree)/scripts/recordmcount.c \
199 $(srctree)/scripts/recordmcount.h
200else
201sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
202 "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
203 "$(if $(CONFIG_64BIT),64,32)" \
204 "$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
205 "$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
206 "$(if $(part-of-module),1,0)" "$(@)";
207recordmcount_source := $(srctree)/scripts/recordmcount.pl
208endif # BUILD_C_RECORDMCOUNT
209cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), \
210 $(sub_cmd_record_mcount))
211endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
212
213# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
214# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
215# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
216
217is-standard-object = $(if $(filter-out y%, $(OBJECT_FILES_NON_STANDARD_$(target-stem).o)$(OBJECT_FILES_NON_STANDARD)n),$(is-kernel-object))
218
219$(obj)/%.o: private objtool-enabled = $(if $(is-standard-object),$(if $(delay-objtool),$(is-single-obj-m),y))
220
221ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
222cmd_warn_shared_object = $(if $(word 2, $(modname-multi)),$(warning $(kbuild-file): $*.o is added to multiple modules: $(modname-multi)))
223endif
224
225define rule_cc_o_c
226 $(call cmd_and_fixdep,cc_o_c)
227 $(call cmd,checksrc)
228 $(call cmd,checkdoc)
229 $(call cmd,gen_objtooldep)
230 $(call cmd,gen_symversions_c)
231 $(call cmd,record_mcount)
232 $(call cmd,warn_shared_object)
233endef
234
235define rule_as_o_S
236 $(call cmd_and_fixdep,as_o_S)
237 $(call cmd,gen_objtooldep)
238 $(call cmd,gen_symversions_S)
239 $(call cmd,warn_shared_object)
240endef
241
242# Built-in and composite module parts
243$(obj)/%.o: $(obj)/%.c $(recordmcount_source) FORCE
244 $(call if_changed_rule,cc_o_c)
245 $(call cmd,force_checksrc)
246
247# To make this rule robust against "Argument list too long" error,
248# ensure to add $(obj)/ prefix by a shell command.
249cmd_mod = printf '%s\n' $(call real-search, $*.o, .o, -objs -y -m) | \
250 $(AWK) '!x[$$0]++ { print("$(obj)/"$$0) }' > $@
251
252$(obj)/%.mod: FORCE
253 $(call if_changed,mod)
254
255quiet_cmd_cc_lst_c = MKLST $@
256 cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
257 $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
258 System.map $(OBJDUMP) > $@
259
260$(obj)/%.lst: $(obj)/%.c FORCE
261 $(call if_changed_dep,cc_lst_c)
262
263# Compile Rust sources (.rs)
264# ---------------------------------------------------------------------------
265
266rust_allowed_features := new_uninit
267
268# `--out-dir` is required to avoid temporaries being created by `rustc` in the
269# current working directory, which may be not accessible in the out-of-tree
270# modules case.
271rust_common_cmd = \
272 RUST_MODFILE=$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \
273 -Zallow-features=$(rust_allowed_features) \
274 -Zcrate-attr=no_std \
275 -Zcrate-attr='feature($(rust_allowed_features))' \
276 -Zunstable-options --extern force:alloc --extern kernel \
277 --crate-type rlib -L $(objtree)/rust/ \
278 --crate-name $(basename $(notdir $@)) \
279 --sysroot=/dev/null \
280 --out-dir $(dir $@) --emit=dep-info=$(depfile)
281
282# `--emit=obj`, `--emit=asm` and `--emit=llvm-ir` imply a single codegen unit
283# will be used. We explicitly request `-Ccodegen-units=1` in any case, and
284# the compiler shows a warning if it is not 1. However, if we ever stop
285# requesting it explicitly and we start using some other `--emit` that does not
286# imply it (and for which codegen is performed), then we would be out of sync,
287# i.e. the outputs we would get for the different single targets (e.g. `.ll`)
288# would not match each other.
289
290quiet_cmd_rustc_o_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
291 cmd_rustc_o_rs = $(rust_common_cmd) --emit=obj=$@ $<
292
293$(obj)/%.o: $(obj)/%.rs FORCE
294 +$(call if_changed_dep,rustc_o_rs)
295
296quiet_cmd_rustc_rsi_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
297 cmd_rustc_rsi_rs = \
298 $(rust_common_cmd) -Zunpretty=expanded $< >$@; \
299 command -v $(RUSTFMT) >/dev/null && $(RUSTFMT) $@
300
301$(obj)/%.rsi: $(obj)/%.rs FORCE
302 +$(call if_changed_dep,rustc_rsi_rs)
303
304quiet_cmd_rustc_s_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
305 cmd_rustc_s_rs = $(rust_common_cmd) --emit=asm=$@ $<
306
307$(obj)/%.s: $(obj)/%.rs FORCE
308 +$(call if_changed_dep,rustc_s_rs)
309
310quiet_cmd_rustc_ll_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
311 cmd_rustc_ll_rs = $(rust_common_cmd) --emit=llvm-ir=$@ $<
312
313$(obj)/%.ll: $(obj)/%.rs FORCE
314 +$(call if_changed_dep,rustc_ll_rs)
315
316# Compile assembler sources (.S)
317# ---------------------------------------------------------------------------
318
319# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
320# or a file that it includes, in order to get versioned symbols. We build a
321# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
322# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
323#
324# This is convoluted. The .S file must first be preprocessed to run guards and
325# expand names, then the resulting exports must be constructed into plain
326# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
327# to make the genksyms input.
328#
329# These mirror gensymtypes_c and co above, keep them in synch.
330cmd_gensymtypes_S = \
331 { echo "\#include <linux/kernel.h>" ; \
332 echo "\#include <asm/asm-prototypes.h>" ; \
333 $(NM) $@ | sed -n 's/.* __export_symbol_\(.*\)/EXPORT_SYMBOL(\1);/p' ; } | \
334 $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | $(genksyms)
335
336quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
337 cmd_cc_symtypes_S = $(call cmd_gensymtypes_S,true,$@) >/dev/null
338
339$(obj)/%.symtypes : $(obj)/%.S FORCE
340 $(call cmd,cc_symtypes_S)
341
342
343quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
344cmd_cpp_s_S = $(CPP) $(a_flags) -o $@ $<
345
346$(obj)/%.s: $(obj)/%.S FORCE
347 $(call if_changed_dep,cpp_s_S)
348
349quiet_cmd_as_o_S = AS $(quiet_modtag) $@
350 cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $< $(cmd_objtool)
351
352ifdef CONFIG_ASM_MODVERSIONS
353
354# versioning matches the C process described above, with difference that
355# we parse asm-prototypes.h C header to get function definitions.
356
357cmd_gen_symversions_S = $(call gen_symversions,S)
358
359endif
360
361$(obj)/%.o: $(obj)/%.S FORCE
362 $(call if_changed_rule,as_o_S)
363
364targets += $(filter-out $(subdir-builtin), $(real-obj-y))
365targets += $(filter-out $(subdir-modorder), $(real-obj-m))
366targets += $(real-dtb-y) $(lib-y) $(always-y)
367
368# Linker scripts preprocessor (.lds.S -> .lds)
369# ---------------------------------------------------------------------------
370quiet_cmd_cpp_lds_S = LDS $@
371 cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
372 -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
373
374$(obj)/%.lds: $(src)/%.lds.S FORCE
375 $(call if_changed_dep,cpp_lds_S)
376
377# ASN.1 grammar
378# ---------------------------------------------------------------------------
379quiet_cmd_asn1_compiler = ASN.1 $(basename $@).[ch]
380 cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
381 $(basename $@).c $(basename $@).h
382
383$(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
384 $(call cmd,asn1_compiler)
385
386# Build the compiled-in targets
387# ---------------------------------------------------------------------------
388
389# To build objects in subdirs, we need to descend into the directories
390$(subdir-builtin): $(obj)/%/built-in.a: $(obj)/% ;
391$(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ;
392$(subdir-dtbslist): $(obj)/%/dtbs-list: $(obj)/% ;
393
394#
395# Rule to compile a set of .o files into one .a file (without symbol table)
396#
397# To make this rule robust against "Argument list too long" error,
398# remove $(obj)/ prefix, and restore it by a shell command.
399
400quiet_cmd_ar_builtin = AR $@
401 cmd_ar_builtin = rm -f $@; \
402 $(if $(real-prereqs), printf "$(obj)/%s " $(patsubst $(obj)/%,%,$(real-prereqs)) | xargs) \
403 $(AR) cDPrST $@
404
405$(obj)/built-in.a: $(real-obj-y) FORCE
406 $(call if_changed,ar_builtin)
407
408#
409# Rule to create modules.order and dtbs-list
410#
411# This is a list of build artifacts (module or dtb) from the current Makefile
412# and its sub-directories. The timestamp should be updated when any of the
413# member files.
414
415cmd_gen_order = { $(foreach m, $(real-prereqs), \
416 $(if $(filter %/$(notdir $@), $m), cat $m, echo $m);) :; } \
417 > $@
418
419$(obj)/modules.order: $(obj-m) FORCE
420 $(call if_changed,gen_order)
421
422$(obj)/dtbs-list: $(dtb-y) FORCE
423 $(call if_changed,gen_order)
424
425#
426# Rule to compile a set of .o files into one .a file (with symbol table)
427#
428
429$(obj)/lib.a: $(lib-y) FORCE
430 $(call if_changed,ar)
431
432quiet_cmd_ld_multi_m = LD [M] $@
433 cmd_ld_multi_m = $(LD) $(ld_flags) -r -o $@ @$< $(cmd_objtool)
434
435define rule_ld_multi_m
436 $(call cmd_and_savecmd,ld_multi_m)
437 $(call cmd,gen_objtooldep)
438endef
439
440$(multi-obj-m): private objtool-enabled := $(delay-objtool)
441$(multi-obj-m): private part-of-module := y
442$(multi-obj-m): %.o: %.mod FORCE
443 $(call if_changed_rule,ld_multi_m)
444$(call multi_depend, $(multi-obj-m), .o, -objs -y -m)
445
446# Add intermediate targets:
447# When building objects with specific suffix patterns, add intermediate
448# targets that the final targets are derived from.
449intermediate_targets = $(foreach sfx, $(2), \
450 $(patsubst %$(strip $(1)),%$(sfx), \
451 $(filter %$(strip $(1)), $(targets))))
452# %.asn1.o <- %.asn1.[ch] <- %.asn1
453# %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
454# %.dtbo.o <- %.dtbo.S <- %.dtbo <- %.dtso
455# %.lex.o <- %.lex.c <- %.l
456# %.tab.o <- %.tab.[ch] <- %.y
457targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
458 $(call intermediate_targets, .dtb.o, .dtb.S .dtb) \
459 $(call intermediate_targets, .dtbo.o, .dtbo.S .dtbo) \
460 $(call intermediate_targets, .lex.o, .lex.c) \
461 $(call intermediate_targets, .tab.o, .tab.c .tab.h)
462
463# Build
464# ---------------------------------------------------------------------------
465
466$(obj)/: $(if $(KBUILD_BUILTIN), $(targets-for-builtin)) \
467 $(if $(KBUILD_MODULES), $(targets-for-modules)) \
468 $(subdir-ym) $(always-y)
469 @:
470
471# Single targets
472# ---------------------------------------------------------------------------
473
474single-subdirs := $(foreach d, $(subdir-ym), $(if $(filter $d/%, $(MAKECMDGOALS)), $d))
475single-subdir-goals := $(filter $(addsuffix /%, $(single-subdirs)), $(MAKECMDGOALS))
476
477$(single-subdir-goals): $(single-subdirs)
478 @:
479
480# Descending
481# ---------------------------------------------------------------------------
482
483PHONY += $(subdir-ym)
484$(subdir-ym):
485 $(Q)$(MAKE) $(build)=$@ \
486 need-builtin=$(if $(filter $@/built-in.a, $(subdir-builtin)),1) \
487 need-modorder=$(if $(filter $@/modules.order, $(subdir-modorder)),1) \
488 $(filter $@/%, $(single-subdir-goals))
489
490# Add FORCE to the prequisites of a target to force it to be always rebuilt.
491# ---------------------------------------------------------------------------
492
493PHONY += FORCE
494
495FORCE:
496
497targets += $(filter-out $(single-subdir-goals), $(MAKECMDGOALS))
498targets := $(filter-out $(PHONY), $(targets))
499
500# Read all saved command lines and dependencies for the $(targets) we
501# may be building above, using $(if_changed{,_dep}). As an
502# optimization, we don't need to read them if the target does not
503# exist, we will rebuild anyway in that case.
504
505existing-targets := $(wildcard $(sort $(targets)))
506
507-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
508
509# Create directories for object files if they do not exist
510obj-dirs := $(sort $(patsubst %/,%, $(dir $(targets))))
511# If targets exist, their directories apparently exist. Skip mkdir.
512existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))
513obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))
514ifneq ($(obj-dirs),)
515$(shell mkdir -p $(obj-dirs))
516endif
517
518.PHONY: $(PHONY)