Lines Matching +full:full +full:- +full:custom
29 architecture-specific information to the top Makefile.
34 any built-in or modular targets.
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
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-$(CONFIG_EXT2_FS_XATTR) += xattr.o xattr_user.o \
189 parts and then link this into built-in.a, as you would expect.
191 Library file goals - lib-y
192 --------------------------
194 Objects listed with obj-* are used for modules, or
195 combined in a built-in.a for that specific directory.
198 All objects listed with lib-y are combined in a single
200 Objects that are listed in obj-y and additionally listed in
201 lib-y will not be included in the library, since they will
203 For consistency, objects listed in lib-m will be included in lib.a.
205 Note that the same kbuild makefile may list files to be built-in
207 may contain both a built-in.a and a lib.a file.
212 lib-y := delay.o
216 shall be listed in libs-y.
220 Use of lib-y is normally restricted to ``lib/`` and ``arch/*/lib``.
223 ------------------------------
231 To do so, obj-y and obj-m are used.
238 obj-$(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
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
325 ccflags-y specifies options for compiling with $(CC).
330 ccflags-y := -Os -D_LINUX -DBUILDING_ACPICA
331 ccflags-$(CONFIG_ACPI_DEBUG) += -DACPI_DEBUG_OUTPUT
337 asflags-y specifies assembler options.
342 asflags-y := -ansi
344 ldflags-y specifies options for linking with $(LD).
349 ldflags-y += -T $(src)/decompress_$(arch-y).lds
351 subdir-ccflags-y, subdir-asflags-y
352 The two flags listed above are similar to ccflags-y and asflags-y.
353 The difference is that the subdir- variants have effect for the kbuild
355 Options specified using subdir-* are added to the commandline before
356 the options specified using the non-subdir variants.
360 subdir-ccflags-y := -Werror
362 ccflags-remove-y, asflags-remove-y
368 ccflags-remove-$(CONFIG_MCOUNT) += -pg
374 $(CFLAGS_$@) specifies per-file options for $(CC). The $@
377 CFLAGS_$@ has the higher priority than ccflags-remove-y; CFLAGS_$@
378 can re-add compiler flags that were removed by ccflags-remove-y.
383 CFLAGS_aha152x.o = -DAHA152X_STAT -DAUTOCONF
390 AFLAGS_$@ has the higher priority than asflags-remove-y; AFLAGS_$@
391 can re-add assembler flags that were removed by asflags-remove-y.
396 AFLAGS_head.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
397 AFLAGS_crunch-bits.o := -Wa,-mcpu=ep9312
398 AFLAGS_iwmmxt.o := -Wa,-mcpu=iwmmxt
401 -------------------
407 3) Command-line used to compile target
410 be re-compiled.
412 Custom Rules
413 ------------
415 Custom rules are used when the kbuild infrastructure does
418 Another example are the architecture-specific Makefiles which
419 need custom rules to prepare boot images etc.
421 Custom rules are written as normal Make rules.
423 located, so all custom rules shall use a relative
426 Two variables are used when defining custom rules:
442 $(CPP) -DCHIP=810 - < $< | ... $(src)/script_asm.pl
444 This is a custom rule, following the normal syntax
468 but when execution ``make -s`` one does not expect to see any output
471 text following $(kecho) to stdout except if ``make -s`` is used.
482 To enable this behaviour for custom commands kbuild requires
485 quiet_cmd_<command> - what shall be echoed
486 cmd_<command> - the command to execute
504 ------------------------
512 Kbuild achieves this by a kind of meta-programming.
527 obj-y/m, lib-y/m, extra-y/m, always-y/m, hostprogs, userprogs, Kbuild
532 used in conjunction with custom rules as defined in `Custom Rules`_.
550 -----------------------
558 as-option
559 as-option is used to check if $(CC) -- when used to compile
560 assembler (``*.S``) files -- supports the given option. An optional
566 cflags-y += $(call as-option,-Wa$(comma)-isa=$(isa-y),)
568 In the above example, cflags-y will be assigned the option
569 -Wa$(comma)-isa=$(isa-y) if it is supported by $(CC).
573 as-instr
574 as-instr checks if the assembler reports a specific instruction
577 Note: as-instr-option uses KBUILD_AFLAGS for assembler options
579 cc-option
580 cc-option is used to check if $(CC) supports a given option, and if
586 cflags-y += $(call cc-option,-march=pentium-mmx,-march=i586)
588 In the above example, cflags-y will be assigned the option
589 -march=pentium-mmx if supported by $(CC), otherwise -march=i586.
590 The second argument to cc-option is optional, and if omitted,
591 cflags-y will be assigned no value if first option is not supported.
592 Note: cc-option uses KBUILD_CFLAGS for $(CC) options
594 cc-option-yn
595 cc-option-yn is used to check if $(CC) supports a given option
601 biarch := $(call cc-option-yn, -m32)
602 aflags-$(biarch) += -a32
603 cflags-$(biarch) += -m32
605 In the above example, $(biarch) is set to y if $(CC) supports the -m32
606 option. When $(biarch) equals "y", the expanded variables $(aflags-y)
607 and $(cflags-y) will be assigned the values -a32 and -m32,
610 Note: cc-option-yn uses KBUILD_CFLAGS for $(CC) options
612 cc-disable-warning
613 cc-disable-warning checks if $(CC) supports a given warning and returns
615 because gcc 4.4 and later accept any unknown -Wno-* option and only
620 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
622 In the above example, -Wno-unused-but-set-variable will be added to
625 gcc-min-version
626 gcc-min-version tests if the value of $(CONFIG_GCC_VERSION) is greater than
631 cflags-$(call gcc-min-version, 70100) := -foo
633 In this example, cflags-y will be assigned the value -foo if $(CC) is gcc and
636 clang-min-version
637 clang-min-version tests if the value of $(CONFIG_CLANG_VERSION) is greater
642 cflags-$(call clang-min-version, 110000) := -foo
644 In this example, cflags-y will be assigned the value -foo if $(CC) is clang
647 cc-cross-prefix
648 cc-cross-prefix is used to check if there exists a $(CC) in path with
650 prefix$(CC) in the PATH is returned - and if no prefix$(CC) is found
654 call of cc-cross-prefix.
657 to set CROSS_COMPILE to well-known values but may have several
669 CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu-)
674 -----------------------
676 ld-option
677 ld-option is used to check if $(LD) supports the supplied option.
678 ld-option takes two options as arguments.
686 LDFLAGS_vmlinux += $(call ld-option, -X)
689 -----------------
721 or utilise the variable ``always-y``.
725 -------------------
738 c-source file named bin2hex.c located in the same directory as
742 -----------------------
747 $(<executable>-objs) lists all objects used to link the final
754 lxdialog-objs := checklist.o lxdialog.o
761 Note: The syntax <executable>-y is not permitted for host-programs.
764 ---------------------------
774 qconf-cxxobjs := qconf.o
777 qconf.cc - identified by $(qconf-cxxobjs).
786 qconf-cxxobjs := qconf.o
787 qconf-objs := check.o
790 ----------------------------
800 target-rust := y
807 ----------------------------------------------
819 HOST_EXTRACFLAGS += -I/usr/include/ncurses
827 HOSTCFLAGS_piggyback.o := -DKERNELBASE=$(KERNELBASE)
834 HOSTLDLIBS_qconf := -L$(QTDIR)/lib
837 ``-L$(QTDIR)/lib``.
840 -------------------------------------
842 Kbuild will only build host-programs when they are referenced
847 (1) List the prerequisite explicitly in a custom rule.
852 hostprogs := gen-devlist
853 $(obj)/devlist.h: $(src)/pci.ids $(obj)/gen-devlist
854 ( cd $(obj); ./gen-devlist ) < $<
857 $(obj)/gen-devlist is updated. Note that references to
858 the host programs in custom rules must be prefixed with $(obj).
860 (2) Use always-y
862 When there is no suitable custom rule, and the host program
863 shall be built when a makefile is entered, the always-y
870 always-y := $(hostprogs)
874 hostprogs-always-y := lxdialog
890 ------------------------
892 The following line tells kbuild that the program bpf-direct shall be
897 userprogs := bpf-direct
899 Kbuild assumes in the above example that bpf-direct is made from a
900 single C source file named bpf-direct.c located in the same directory
904 ----------------------------
909 $(<executable>-objs) lists all objects used to link the final
915 userprogs := bpf-fancy
916 bpf-fancy-objs := bpf-fancy.o bpf-helper.o
919 files. In the above example, bpf-fancy.c is compiled to bpf-fancy.o
920 and bpf-helper.c is compiled to bpf-helper.o.
922 Finally, the two .o files are linked to the executable, bpf-fancy.
923 Note: The syntax <executable>-y is not permitted for userspace programs.
926 ---------------------------------------------------
938 userccflags += -I usr/include
945 bpf-helper-userccflags += -I user/include
952 bpfilter_umh-userldflags += -static
955 ``<executable>-userldlibs``. The ``userldlibs`` syntax specifies libraries
958 When linking bpfilter_umh, it will be passed the extra option -static.
963 ------------------------------------------
978 (2) Use always-y
983 always-y := $(userprogs)
987 userprogs-always-y := binderfs_example
997 Kbuild knows targets listed in $(hostprogs), $(always-y), $(always-m),
998 $(always-), $(extra-y), $(extra-) and $(targets). They are all deleted
1004 $(clean-files).
1009 clean-files := crc32table.h
1016 $(no-clean-files) variable.
1018 Usually kbuild descends down in subdirectories due to ``obj-* := dir/``,
1025 subdir- := compressed
1030 Note 1: arch/$(SRCARCH)/Makefile cannot use ``subdir-``, because that file is
1032 ``subdir-``.
1034 Note 2: All directories listed in core-y, libs-y, drivers-y and net-y will
1058 - Additional prerequisites are specified in arch/$(SRCARCH)/Makefile
1061 init-* core* drivers-* net-* libs-* and build all targets.
1063 - The values of the above variables are expanded in arch/$(SRCARCH)/Makefile.
1067 The very first objects linked are listed in scripts/head-object-list.txt.
1069 6) Finally, the architecture-specific part does any required post processing
1072 - This includes building boot records
1073 - Preparing initrd images and the like
1076 ----------------------------------------------------
1087 KBUILD_LDFLAGS := -m elf_s390
1089 Note: ldflags-y can be used to further customise
1090 the flags used. See `Non-builtin vmlinux targets - extra-y`_.
1103 LDFLAGS_vmlinux := -e stext
1117 OBJCOPYFLAGS := -O binary
1129 Default value - see top level Makefile.
1136 KBUILD_AFLAGS += -m64 -mcpu=ultrasparc
1141 Default value - see top level Makefile.
1150 cflags-$(CONFIG_X86_32) := -march=i386
1151 cflags-$(CONFIG_X86_64) := -mcmodel=small
1152 KBUILD_CFLAGS += $(cflags-y)
1160 cflags-$(CONFIG_MPENTIUMII) += $(call cc-option,\
1161 -march=pentium2,-march=i686)
1163 # Disable unit-at-a-time mode ...
1164 KBUILD_CFLAGS += $(call cc-option,-fno-unit-at-a-time)
1174 Default value - see top level Makefile.
1180 Note that target specification file generation (for ``--target``)
1184 Assembler options specific for built-in
1192 $(KBUILD_AFLAGS_MODULE) is used to add arch-specific options that
1198 $(CC) options specific for built-in
1206 $(KBUILD_CFLAGS_MODULE) is used to add arch-specific options that
1212 $(RUSTC) options specific for built-in
1220 $(KBUILD_RUSTFLAGS_MODULE) is used to add arch-specific options that
1228 $(KBUILD_LDFLAGS_MODULE) is used to add arch-specific options
1234 The linker script with full path. Assigned by the top-level Makefile.
1240 The objects listed in scripts/head-object-list.txt are exceptions;
1249 --------------------------------
1258 --------------------------------
1273 See also chapter XXX-TODO that describes how kbuild supports
1277 -----------------------------------------
1281 corresponding arch-specific section for modules; the module-building
1282 machinery is all architecture-independent.
1284 core-y, libs-y, drivers-y
1285 $(libs-y) lists directories where a lib.a archive can be located.
1287 The rest list directories where a built-in.a object file can be
1292 $(core-y), $(libs-y), $(drivers-y)
1295 and arch/$(SRCARCH)/Makefile only adds architecture-specific
1301 core-y += arch/sparc/
1303 libs-y += arch/sparc/prom/
1304 libs-y += arch/sparc/lib/
1306 drivers-$(CONFIG_PM) += arch/sparc/power/
1308 Architecture-specific boot images
1309 ---------------------------------
1324 arch/$(SRCARCH)/Makefile, and use the full path when calling down
1337 There are no rules for naming architecture-specific targets,
1345 echo '* bzImage - Compressed kernel image (arch/x86/boot/bzImage)'
1366 -----------------------------------------
1377 LDFLAGS_bootsect := -Ttext 0x0 -s --oformat binary
1378 LDFLAGS_setup := -Ttext 0x0 -s --oformat binary -e begtext
1386 LDFLAGS_$@ syntax - one for each potential target.
1414 $(obj)/vmlinux.bin.gz: $(vmlinux.bin.all-y) FORCE
1421 blob to non-init memory prior to calling unflatten_device_tree().
1423 To use this command, simply add ``*.dtb`` into obj-y or targets, or make
1431 targets += $(dtb-y)
1432 DTC_FLAGS ?= -p 1024
1435 ----------------------------
1443 kbuild knows .lds files and includes a rule ``*lds.S`` -> ``*lds``.
1448 extra-y := vmlinux.lds
1450 The assignment to extra-y is used to tell kbuild to build the
1458 KBUILD_CPPFLAGS : Set in top-level Makefile
1459 cppflags-y : May be set in the kbuild makefile
1460 CPPFLAGS_$(@F) : Target-specific flags.
1461 Note that the full filename is used in this
1465 architecture-specific files.
1468 --------------------
1470 The directory include/asm-generic contains the header files
1476 See `generic-y`_ for further info on syntax etc.
1478 Post-link pass
1479 --------------
1482 will be invoked for post-link objects (vmlinux and modules.ko)
1483 for architectures to run post-link passes on. Must also handle
1489 .tmp_vmlinux? targets to be called from link-vmlinux.sh.
1498 Many headers can be exported as-is but other headers require a
1499 minimal pre-processing before they are ready for user-space.
1501 The pre-processing does:
1503 - drop kernel-specific annotations
1504 - drop include of compiler.h
1505 - drop all sections that are kernel internal (guarded by ``ifdef __KERNEL__``)
1512 arch/<arch>/include/asm/ to list asm files coming from asm-generic.
1516 no-export-headers
1517 -----------------
1519 no-export-headers is essentially used by include/uapi/linux/Kbuild to
1523 generic-y
1524 ---------
1527 include/asm-generic then this is listed in the file
1533 generic-y += termios.h
1534 generic-y += rtc.h
1551 #include <asm-generic/termios.h>
1553 generated-y
1554 -----------
1556 If an architecture generates other header files alongside generic-y
1557 wrappers, generated-y specifies them.
1559 This prevents them being treated as stale asm-generic wrappers and
1565 generated-y += syscalls_32.h
1567 mandatory-y
1568 -----------
1570 mandatory-y is essentially used by include/(uapi/)asm-generic/Kbuild
1573 This works like optional generic-y. If a mandatory header is missing
1575 generate a wrapper of the asm-generic one.
1588 three-part version number, such as "2", "4", and "0". These three
1591 $(EXTRAVERSION) defines an even tinier sublevel for pre-patches
1592 or additional patches. It is usually some non-numeric string
1593 such as "-pre4", and is often blank.
1596 $(KERNELRELEASE) is a single string such as "2.4.0-pre4", suitable
1616 both 32-bit and 64-bit.
1625 Use this for architecture-specific install targets.
1640 default option --strip-debug will be used. Otherwise, the
1658 GNU Make supports elementary list-processing functions. The kernel
1663 immediate evaluation of the right-hand side and stores an actual string
1664 into the left-hand side. ``=`` is like a formula definition; it stores the
1665 right-hand side in an unevaluated form and then evaluates this form each
1666 time the left-hand side is used.
1674 - Original version made by Michael Elizabeth Chastain, <mailto:mec@shout.net>
1675 - Updates by Kai Germaschewski <kai@tp1.ruhr-uni-bochum.de>
1676 - Updates by Sam Ravnborg <sam@ravnborg.org>
1677 - Language QA by Jan Engelhardt <jengelh@gmx.de>
1682 - Generating offset header files.
1683 - Add more variables to chapters 7 or 9?