Lines Matching +full:build +full:- +full:rules
15 scripts/Makefile.* common rules etc. for all kbuild Makefiles.
29 architecture-specific information to the top Makefile.
33 .config file to construct various file lists used by kbuild to build
34 any built-in or modular targets.
36 scripts/Makefile.* contains all the definitions/rules etc. that
37 are used to build the kernel based on the kbuild makefiles.
44 *Users* are people who build kernels. These people type commands such as
59 *Kbuild developers* are people who work on the kernel build system itself.
80 ----------------
90 obj-y += foo.o
95 If foo.o shall be built as a module, the variable obj-m is used.
100 obj-$(CONFIG_FOO) += foo.o
102 $(CONFIG_FOO) evaluates to either y (for built-in) or m (for module).
106 Built-in object goals - obj-y
107 -----------------------------
110 in the $(obj-y) lists. These lists depend on the kernel
113 Kbuild compiles all the $(obj-y) files. It then calls
114 ``$(AR) rcSTP`` to merge these files into one built-in.a file.
116 linked into vmlinux by scripts/link-vmlinux.sh
118 The order of files in $(obj-y) is significant. Duplicates in
120 built-in.a and succeeding instances will be ignored.
133 obj-$(CONFIG_ISDN_I4L) += isdn.o
134 obj-$(CONFIG_ISDN_PPP_BSDCOMP) += isdn_bsdcomp.o
136 Loadable module goals - obj-m
137 -----------------------------
139 $(obj-m) specifies object files which are built as loadable
144 simply adds the file to $(obj-m).
149 obj-$(CONFIG_ISDN_PPP_BSDCOMP) += isdn_bsdcomp.o
154 that you want to build a module in the same way as above; however,
155 kbuild needs to know which object files you want to build your
156 module from, so you have to tell it by setting a $(<module_name>-y)
162 obj-$(CONFIG_ISDN_I4L) += isdn.o
163 isdn-y := isdn_net_lib.o isdn_v110.o isdn_common.o
166 compile the objects listed in $(isdn-y) and then run
167 ``$(LD) -r`` on the list of these files to generate isdn.o.
169 Due to kbuild recognizing $(<module_name>-y) for composite objects,
176 obj-$(CONFIG_EXT2_FS) += ext2.o
177 ext2-y := balloc.o dir.o file.o ialloc.o inode.o ioctl.o \
179 ext2-$(CONFIG_EXT2_FS_XATTR) += xattr.o xattr_user.o \
188 kbuild will build an ext2.o file for you out of the individual
189 parts and then link this into built-in.a, as you would expect.
191 Library file goals - lib-y
192 --------------------------
194 Objects listed with obj-* are used for modules, or
195 combined in a built-in.a for that specific directory.
198 All objects listed with lib-y are combined in a single
200 Objects that are listed in obj-y and additionally listed in
201 lib-y will not be included in the library, since they will
203 For consistency, objects listed in lib-m will be included in lib.a.
205 Note that the same kbuild makefile may list files to be built-in
207 may contain both a built-in.a and a lib.a file.
212 lib-y := delay.o
216 shall be listed in libs-y.
220 Use of lib-y is normally restricted to ``lib/`` and ``arch/*/lib``.
223 ------------------------------
227 Makefiles in these subdirs. The build system will automatically
231 To do so, obj-y and obj-m are used.
238 obj-$(CONFIG_EXT2_FS) += ext2/
240 If CONFIG_EXT2_FS is set to either "y" (built-in) or "m" (modular)
241 the corresponding obj- variable will be set, and kbuild will descend
248 When Kbuild descends into the directory with "y", all built-in objects
249 from that directory are combined into the built-in.a, which will be
254 that directory specifies obj-y, those objects will be left orphan.
257 Kbuild also supports dedicated syntax, subdir-y and subdir-m, for
259 do not contain kernel-space objects at all. A typical usage is to let
260 Kbuild descend into subdirectories to build tools.
265 subdir-$(CONFIG_GCC_PLUGINS) += gcc-plugins
266 subdir-$(CONFIG_MODVERSIONS) += genksyms
267 subdir-$(CONFIG_SECURITY_SELINUX) += selinux
269 Unlike obj-y/m, subdir-y/m does not need the trailing slash since this
276 Non-builtin vmlinux targets - extra-y
277 -------------------------------------
279 extra-y specifies targets which are needed for building vmlinux,
280 but not combined into built-in.a.
292 extra-y += vmlinux.lds
294 $(extra-y) should only contain targets needed for vmlinux.
296 Kbuild skips extra-y when vmlinux is apparently not a final goal.
299 If you intend to build targets unconditionally, always-y (explained
302 Always built goals - always-y
303 -----------------------------
305 always-y specifies targets which are literally always built when
311 offsets-file := include/generated/asm-offsets.h
312 always-y += $(offsets-file)
315 -----------------
317 ccflags-y, asflags-y and ldflags-y
320 invocations happening during a recursive build.
322 ccflags-y specifies options for compiling with $(CC).
327 ccflags-y := -Os -D_LINUX -DBUILDING_ACPICA
328 ccflags-$(CONFIG_ACPI_DEBUG) += -DACPI_DEBUG_OUTPUT
334 asflags-y specifies assembler options.
339 asflags-y := -ansi
341 ldflags-y specifies options for linking with $(LD).
346 ldflags-y += -T $(src)/decompress_$(arch-y).lds
348 subdir-ccflags-y, subdir-asflags-y
349 The two flags listed above are similar to ccflags-y and asflags-y.
350 The difference is that the subdir- variants have effect for the kbuild
352 Options specified using subdir-* are added to the commandline before
353 the options specified using the non-subdir variants.
357 subdir-ccflags-y := -Werror
359 ccflags-remove-y, asflags-remove-y
365 ccflags-remove-$(CONFIG_MCOUNT) += -pg
371 $(CFLAGS_$@) specifies per-file options for $(CC). The $@
374 CFLAGS_$@ has the higher priority than ccflags-remove-y; CFLAGS_$@
375 can re-add compiler flags that were removed by ccflags-remove-y.
380 CFLAGS_aha152x.o = -DAHA152X_STAT -DAUTOCONF
387 AFLAGS_$@ has the higher priority than asflags-remove-y; AFLAGS_$@
388 can re-add assembler flags that were removed by asflags-remove-y.
393 AFLAGS_head.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
394 AFLAGS_crunch-bits.o := -Wa,-mcpu=ep9312
395 AFLAGS_iwmmxt.o := -Wa,-mcpu=iwmmxt
398 -------------------
404 3) Command-line used to compile target
407 be re-compiled.
409 Custom Rules
410 ------------
412 Custom rules are used when the kbuild infrastructure does
414 header files generated during the build process.
415 Another example are the architecture-specific Makefiles which
416 need custom rules to prepare boot images etc.
418 Custom rules are written as normal Make rules.
420 located, so all custom rules shall use a relative
423 Two variables are used when defining custom rules:
431 referring to generated files. Use $(obj) for pattern rules that need to work
439 $(CPP) -DCHIP=810 - < $< | ... $(src)/script_asm.pl
465 but when execution ``make -s`` one does not expect to see any output
468 text following $(kecho) to stdout except if ``make -s`` is used.
474 $(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $(boot)/$@
482 quiet_cmd_<command> - what shall be echoed
483 cmd_<command> - the command to execute
501 ------------------------
509 Kbuild achieves this by a kind of meta-programming.
524 obj-y/m, lib-y/m, extra-y/m, always-y/m, hostprogs, userprogs, Kbuild
529 used in conjunction with custom rules as defined in `Custom Rules`_.
547 -----------------------
555 as-option
556 as-option is used to check if $(CC) -- when used to compile
557 assembler (``*.S``) files -- supports the given option. An optional
563 cflags-y += $(call as-option,-Wa$(comma)-isa=$(isa-y),)
565 In the above example, cflags-y will be assigned the option
566 -Wa$(comma)-isa=$(isa-y) if it is supported by $(CC).
570 as-instr
571 as-instr checks if the assembler reports a specific instruction
574 Note: as-instr-option uses KBUILD_AFLAGS for assembler options
576 cc-option
577 cc-option is used to check if $(CC) supports a given option, and if
583 cflags-y += $(call cc-option,-march=pentium-mmx,-march=i586)
585 In the above example, cflags-y will be assigned the option
586 -march=pentium-mmx if supported by $(CC), otherwise -march=i586.
587 The second argument to cc-option is optional, and if omitted,
588 cflags-y will be assigned no value if first option is not supported.
589 Note: cc-option uses KBUILD_CFLAGS for $(CC) options
591 cc-option-yn
592 cc-option-yn is used to check if $(CC) supports a given option
598 biarch := $(call cc-option-yn, -m32)
599 aflags-$(biarch) += -a32
600 cflags-$(biarch) += -m32
602 In the above example, $(biarch) is set to y if $(CC) supports the -m32
603 option. When $(biarch) equals "y", the expanded variables $(aflags-y)
604 and $(cflags-y) will be assigned the values -a32 and -m32,
607 Note: cc-option-yn uses KBUILD_CFLAGS for $(CC) options
609 cc-disable-warning
610 cc-disable-warning checks if $(CC) supports a given warning and returns
612 because gcc 4.4 and later accept any unknown -Wno-* option and only
617 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
619 In the above example, -Wno-unused-but-set-variable will be added to
622 gcc-min-version
623 gcc-min-version tests if the value of $(CONFIG_GCC_VERSION) is greater than
628 cflags-$(call gcc-min-version, 70100) := -foo
630 In this example, cflags-y will be assigned the value -foo if $(CC) is gcc and
633 clang-min-version
634 clang-min-version tests if the value of $(CONFIG_CLANG_VERSION) is greater
639 cflags-$(call clang-min-version, 110000) := -foo
641 In this example, cflags-y will be assigned the value -foo if $(CC) is clang
644 cc-cross-prefix
645 cc-cross-prefix is used to check if there exists a $(CC) in path with
647 prefix$(CC) in the PATH is returned - and if no prefix$(CC) is found
651 call of cc-cross-prefix.
654 to set CROSS_COMPILE to well-known values but may have several
658 build (host arch is different from target arch). And if CROSS_COMPILE
666 CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu-)
671 --------------------------
673 rustc-min-version
674 rustc-min-version tests if the value of $(CONFIG_RUSTC_VERSION) is greater
679 rustflags-$(call rustc-min-version, 108500) := -Cfoo
681 In this example, rustflags-y will be assigned the value -Cfoo if
685 -----------------------
687 ld-option
688 ld-option is used to check if $(LD) supports the supplied option.
689 ld-option takes two options as arguments.
697 LDFLAGS_vmlinux += $(call ld-option, -X)
700 -----------------
702 Make rules may invoke scripts to build the kernel. The rules shall
732 or utilise the variable ``always-y``.
736 -------------------
739 computer where the build is running.
742 built on the build host.
749 c-source file named bin2hex.c located in the same directory as
753 -----------------------
758 $(<executable>-objs) lists all objects used to link the final
765 lxdialog-objs := checklist.o lxdialog.o
772 Note: The syntax <executable>-y is not permitted for host-programs.
775 ---------------------------
785 qconf-cxxobjs := qconf.o
788 qconf.cc - identified by $(qconf-cxxobjs).
797 qconf-cxxobjs := qconf.o
798 qconf-objs := check.o
801 ----------------------------
811 target-rust := y
818 ----------------------------------------------
830 HOST_EXTRACFLAGS += -I/usr/include/ncurses
838 HOSTCFLAGS_piggyback.o := -DKERNELBASE=$(KERNELBASE)
845 HOSTLDLIBS_qconf := -L$(QTDIR)/lib
848 ``-L$(QTDIR)/lib``.
851 -------------------------------------
853 Kbuild will only build host-programs when they are referenced
863 hostprogs := gen-devlist
864 $(obj)/devlist.h: $(src)/pci.ids $(obj)/gen-devlist
865 ( cd $(obj); ./gen-devlist ) < $<
868 $(obj)/gen-devlist is updated. Note that references to
869 the host programs in custom rules must be prefixed with $(obj).
871 (2) Use always-y
874 shall be built when a makefile is entered, the always-y
881 always-y := $(hostprogs)
885 hostprogs-always-y := lxdialog
887 This will tell kbuild to build lxdialog even if not referenced in
901 ------------------------
903 The following line tells kbuild that the program bpf-direct shall be
908 userprogs := bpf-direct
910 Kbuild assumes in the above example that bpf-direct is made from a
911 single C source file named bpf-direct.c located in the same directory
915 ----------------------------
920 $(<executable>-objs) lists all objects used to link the final
926 userprogs := bpf-fancy
927 bpf-fancy-objs := bpf-fancy.o bpf-helper.o
930 files. In the above example, bpf-fancy.c is compiled to bpf-fancy.o
931 and bpf-helper.c is compiled to bpf-helper.o.
933 Finally, the two .o files are linked to the executable, bpf-fancy.
934 Note: The syntax <executable>-y is not permitted for userspace programs.
937 ---------------------------------------------------
949 userccflags += -I usr/include
956 bpf-helper-userccflags += -I user/include
963 bpfilter_umh-userldflags += -static
966 ``<executable>-userldlibs``. The ``userldlibs`` syntax specifies libraries
969 When linking bpfilter_umh, it will be passed the extra option -static.
974 ------------------------------------------
989 (2) Use always-y
994 always-y := $(userprogs)
998 userprogs-always-y := binderfs_example
1000 This will tell Kbuild to build binderfs_example when it visits this
1008 Kbuild knows targets listed in $(hostprogs), $(always-y), $(always-m),
1009 $(always-), $(extra-y), $(extra-) and $(targets). They are all deleted
1015 $(clean-files).
1020 clean-files := crc32table.h
1027 $(no-clean-files) variable.
1029 Usually kbuild descends down in subdirectories due to ``obj-* := dir/``,
1036 subdir- := compressed
1041 Note 1: arch/$(SRCARCH)/Makefile cannot use ``subdir-``, because that file is
1043 ``subdir-``.
1045 Note 2: All directories listed in core-y, libs-y, drivers-y and net-y will
1069 - Additional prerequisites are specified in arch/$(SRCARCH)/Makefile
1072 init-* core* drivers-* net-* libs-* and build all targets.
1074 - The values of the above variables are expanded in arch/$(SRCARCH)/Makefile.
1078 The very first objects linked are listed in scripts/head-object-list.txt.
1080 6) Finally, the architecture-specific part does any required post processing
1083 - This includes building boot records
1084 - Preparing initrd images and the like
1086 Set variables to tweak the build to the architecture
1087 ----------------------------------------------------
1098 KBUILD_LDFLAGS := -m elf_s390
1100 Note: ldflags-y can be used to further customise
1101 the flags used. See `Non-builtin vmlinux targets - extra-y`_.
1114 LDFLAGS_vmlinux := -e stext
1128 OBJCOPYFLAGS := -O binary
1140 Default value - see top level Makefile.
1147 KBUILD_AFLAGS += -m64 -mcpu=ultrasparc
1152 Default value - see top level Makefile.
1161 cflags-$(CONFIG_X86_32) := -march=i386
1162 cflags-$(CONFIG_X86_64) := -mcmodel=small
1163 KBUILD_CFLAGS += $(cflags-y)
1171 cflags-$(CONFIG_MPENTIUMII) += $(call cc-option,\
1172 -march=pentium2,-march=i686)
1174 # Disable unit-at-a-time mode ...
1175 KBUILD_CFLAGS += $(call cc-option,-fno-unit-at-a-time)
1185 Default value - see top level Makefile.
1191 Note that target specification file generation (for ``--target``)
1195 Assembler options specific for built-in
1203 $(KBUILD_AFLAGS_MODULE) is used to add arch-specific options that
1209 $(CC) options specific for built-in
1217 $(KBUILD_CFLAGS_MODULE) is used to add arch-specific options that
1223 $(RUSTC) options specific for built-in
1231 $(KBUILD_RUSTFLAGS_MODULE) is used to add arch-specific options that
1239 $(KBUILD_LDFLAGS_MODULE) is used to add arch-specific options
1245 The linker script with full path. Assigned by the top-level Makefile.
1251 The objects listed in scripts/head-object-list.txt are exceptions;
1260 --------------------------------
1269 --------------------------------
1284 See also chapter XXX-TODO that describes how kbuild supports
1288 -----------------------------------------
1291 which specify how to build the vmlinux file. Note that there is no
1292 corresponding arch-specific section for modules; the module-building
1293 machinery is all architecture-independent.
1295 core-y, libs-y, drivers-y
1296 $(libs-y) lists directories where a lib.a archive can be located.
1298 The rest list directories where a built-in.a object file can be
1303 $(core-y), $(libs-y), $(drivers-y)
1306 and arch/$(SRCARCH)/Makefile only adds architecture-specific
1312 core-y += arch/sparc/
1314 libs-y += arch/sparc/prom/
1315 libs-y += arch/sparc/lib/
1317 drivers-$(CONFIG_PM) += arch/sparc/power/
1319 Architecture-specific boot images
1320 ---------------------------------
1332 call make manually to build a target in boot/.
1343 $(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
1345 ``$(Q)$(MAKE) $(build)=<dir>`` is the recommended way to invoke
1348 There are no rules for naming architecture-specific targets,
1356 echo '* bzImage - Compressed kernel image (arch/x86/boot/bzImage)'
1363 An architecture shall always, per default, build a bootable image.
1377 -----------------------------------------
1388 LDFLAGS_bootsect := -Ttext 0x0 -s --oformat binary
1389 LDFLAGS_setup := -Ttext 0x0 -s --oformat binary -e begtext
1397 LDFLAGS_$@ syntax - one for each potential target.
1425 $(obj)/vmlinux.bin.gz: $(vmlinux.bin.all-y) FORCE
1432 blob to non-init memory prior to calling unflatten_device_tree().
1434 To use this command, simply add ``*.dtb`` into obj-y or targets, or make
1442 targets += $(dtb-y)
1443 DTC_FLAGS ?= -p 1024
1446 ----------------------------
1454 kbuild knows .lds files and includes a rule ``*lds.S`` -> ``*lds``.
1459 extra-y := vmlinux.lds
1461 The assignment to extra-y is used to tell kbuild to build the
1469 KBUILD_CPPFLAGS : Set in top-level Makefile
1470 cppflags-y : May be set in the kbuild makefile
1471 CPPFLAGS_$(@F) : Target-specific flags.
1476 architecture-specific files.
1479 --------------------
1481 The directory include/asm-generic contains the header files
1487 See `generic-y`_ for further info on syntax etc.
1489 Post-link pass
1490 --------------
1493 will be invoked for post-link objects (vmlinux and modules.ko)
1494 for architectures to run post-link passes on. Must also handle
1500 .tmp_vmlinux? targets to be called from link-vmlinux.sh.
1509 Many headers can be exported as-is but other headers require a
1510 minimal pre-processing before they are ready for user-space.
1512 The pre-processing does:
1514 - drop kernel-specific annotations
1515 - drop include of compiler.h
1516 - drop all sections that are kernel internal (guarded by ``ifdef __KERNEL__``)
1523 arch/<arch>/include/asm/ to list asm files coming from asm-generic.
1527 no-export-headers
1528 -----------------
1530 no-export-headers is essentially used by include/uapi/linux/Kbuild to
1534 generic-y
1535 ---------
1538 include/asm-generic then this is listed in the file
1544 generic-y += termios.h
1545 generic-y += rtc.h
1547 During the prepare phase of the build a wrapper include
1562 #include <asm-generic/termios.h>
1564 generated-y
1565 -----------
1567 If an architecture generates other header files alongside generic-y
1568 wrappers, generated-y specifies them.
1570 This prevents them being treated as stale asm-generic wrappers and
1576 generated-y += syscalls_32.h
1578 mandatory-y
1579 -----------
1581 mandatory-y is essentially used by include/(uapi/)asm-generic/Kbuild
1584 This works like optional generic-y. If a mandatory header is missing
1586 generate a wrapper of the asm-generic one.
1599 three-part version number, such as "2", "4", and "0". These three
1602 $(EXTRAVERSION) defines an even tinier sublevel for pre-patches
1603 or additional patches. It is usually some non-numeric string
1604 such as "-pre4", and is often blank.
1607 $(KERNELRELEASE) is a single string such as "2.4.0-pre4", suitable
1617 host system architecture. For a cross build, a user may
1623 This variable specifies the directory in arch/ to build.
1627 both 32-bit and 64-bit.
1636 Use this for architecture-specific install targets.
1651 default option --strip-debug will be used. Otherwise, the
1656 This variable specifies a prefix for relocations required by build
1669 GNU Make supports elementary list-processing functions. The kernel
1674 immediate evaluation of the right-hand side and stores an actual string
1675 into the left-hand side. ``=`` is like a formula definition; it stores the
1676 right-hand side in an unevaluated form and then evaluates this form each
1677 time the left-hand side is used.
1685 - Original version made by Michael Elizabeth Chastain, <mailto:mec@shout.net>
1686 - Updates by Kai Germaschewski <kai@tp1.ruhr-uni-bochum.de>
1687 - Updates by Sam Ravnborg <sam@ravnborg.org>
1688 - Language QA by Jan Engelhardt <jengelh@gmx.de>
1693 - Generating offset header files.
1694 - Add more variables to chapters 7 or 9?