Lines Matching +full:pre +full:- +full:programs
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.
413 ------------
418 Another example are the architecture-specific Makefiles which
442 $(CPP) -DCHIP=810 - < $< | ... $(src)/script_asm.pl
454 but when execution ``make -s`` one does not expect to see any output
457 text following $(kecho) to stdout except if ``make -s`` is used.
471 quiet_cmd_<command> - what shall be echoed
472 cmd_<command> - the command to execute
490 ------------------------
498 Kbuild achieves this by a kind of meta-programming.
513 obj-y/m, lib-y/m, extra-y/m, always-y/m, hostprogs, userprogs, Kbuild
536 -----------------------
544 as-option
545 as-option is used to check if $(CC) -- when used to compile
546 assembler (``*.S``) files -- supports the given option. An optional
552 cflags-y += $(call as-option,-Wa$(comma)-isa=$(isa-y),)
554 In the above example, cflags-y will be assigned the option
555 -Wa$(comma)-isa=$(isa-y) if it is supported by $(CC).
559 as-instr
560 as-instr checks if the assembler reports a specific instruction
563 Note: as-instr-option uses KBUILD_AFLAGS for assembler options
565 cc-option
566 cc-option is used to check if $(CC) supports a given option, and if
572 cflags-y += $(call cc-option,-march=pentium-mmx,-march=i586)
574 In the above example, cflags-y will be assigned the option
575 -march=pentium-mmx if supported by $(CC), otherwise -march=i586.
576 The second argument to cc-option is optional, and if omitted,
577 cflags-y will be assigned no value if first option is not supported.
578 Note: cc-option uses KBUILD_CFLAGS for $(CC) options
580 cc-option-yn
581 cc-option-yn is used to check if $(CC) supports a given option
587 biarch := $(call cc-option-yn, -m32)
588 aflags-$(biarch) += -a32
589 cflags-$(biarch) += -m32
591 In the above example, $(biarch) is set to y if $(CC) supports the -m32
592 option. When $(biarch) equals "y", the expanded variables $(aflags-y)
593 and $(cflags-y) will be assigned the values -a32 and -m32,
596 Note: cc-option-yn uses KBUILD_CFLAGS for $(CC) options
598 cc-disable-warning
599 cc-disable-warning checks if $(CC) supports a given warning and returns
601 because gcc 4.4 and later accept any unknown -Wno-* option and only
606 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
608 In the above example, -Wno-unused-but-set-variable will be added to
611 gcc-min-version
612 gcc-min-version tests if the value of $(CONFIG_GCC_VERSION) is greater than
617 cflags-$(call gcc-min-version, 70100) := -foo
619 In this example, cflags-y will be assigned the value -foo if $(CC) is gcc and
622 clang-min-version
623 clang-min-version tests if the value of $(CONFIG_CLANG_VERSION) is greater
628 cflags-$(call clang-min-version, 110000) := -foo
630 In this example, cflags-y will be assigned the value -foo if $(CC) is clang
633 cc-cross-prefix
634 cc-cross-prefix is used to check if there exists a $(CC) in path with
636 prefix$(CC) in the PATH is returned - and if no prefix$(CC) is found
640 call of cc-cross-prefix.
643 to set CROSS_COMPILE to well-known values but may have several
655 CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu-)
660 -----------------------
662 ld-option
663 ld-option is used to check if $(LD) supports the supplied option.
664 ld-option takes two options as arguments.
672 LDFLAGS_vmlinux += $(call ld-option, -X)
675 -----------------
707 or utilise the variable ``always-y``.
711 -------------------
724 c-source file named bin2hex.c located in the same directory as
727 Composite Host Programs
728 -----------------------
730 Host programs can be made up based on composite objects.
731 The syntax used to define composite objects for host programs is
733 $(<executable>-objs) lists all objects used to link the final
740 lxdialog-objs := checklist.o lxdialog.o
747 Note: The syntax <executable>-y is not permitted for host-programs.
749 Using C++ for host programs
750 ---------------------------
752 kbuild offers support for host programs written in C++. This was
760 qconf-cxxobjs := qconf.o
763 qconf.cc - identified by $(qconf-cxxobjs).
772 qconf-cxxobjs := qconf.o
773 qconf-objs := check.o
775 Using Rust for host programs
776 ----------------------------
778 Kbuild offers support for host programs written in Rust. However,
786 target-rust := y
792 Controlling compiler options for host programs
793 ----------------------------------------------
795 When compiling host programs, it is possible to set specific flags.
796 The programs will always be compiled utilising $(HOSTCC) passed
799 To set flags that will take effect for all host programs created
805 HOST_EXTRACFLAGS += -I/usr/include/ncurses
813 HOSTCFLAGS_piggyback.o := -DKERNELBASE=$(KERNELBASE)
820 HOSTLDLIBS_qconf := -L$(QTDIR)/lib
823 ``-L$(QTDIR)/lib``.
825 When host programs are actually built
826 -------------------------------------
828 Kbuild will only build host-programs when they are referenced
838 hostprogs := gen-devlist
839 $(obj)/devlist.h: $(src)/pci.ids $(obj)/gen-devlist
840 ( cd $(obj); ./gen-devlist ) < $<
843 $(obj)/gen-devlist is updated. Note that references to
844 the host programs in custom rules must be prefixed with $(obj).
846 (2) Use always-y
849 shall be built when a makefile is entered, the always-y
856 always-y := $(hostprogs)
860 hostprogs-always-y := lxdialog
868 Just like host programs, Kbuild also supports building userspace executables
876 ------------------------
878 The following line tells kbuild that the program bpf-direct shall be
883 userprogs := bpf-direct
885 Kbuild assumes in the above example that bpf-direct is made from a
886 single C source file named bpf-direct.c located in the same directory
889 Composite Userspace Programs
890 ----------------------------
892 Userspace programs can be made up based on composite objects.
893 The syntax used to define composite objects for userspace programs is
895 $(<executable>-objs) lists all objects used to link the final
901 userprogs := bpf-fancy
902 bpf-fancy-objs := bpf-fancy.o bpf-helper.o
905 files. In the above example, bpf-fancy.c is compiled to bpf-fancy.o
906 and bpf-helper.c is compiled to bpf-helper.o.
908 Finally, the two .o files are linked to the executable, bpf-fancy.
909 Note: The syntax <executable>-y is not permitted for userspace programs.
911 Controlling compiler options for userspace programs
912 ---------------------------------------------------
914 When compiling userspace programs, it is possible to set specific flags.
915 The programs will always be compiled utilising $(CC) passed
918 To set flags that will take effect for all userspace programs created
924 userccflags += -I usr/include
931 bpf-helper-userccflags += -I user/include
938 bpfilter_umh-userldflags += -static
941 ``<executable>-userldlibs``. The ``userldlibs`` syntax specifies libraries
942 linked to all userspace programs created in the current Makefile.
944 When linking bpfilter_umh, it will be passed the extra option -static.
948 When userspace programs are actually built
949 ------------------------------------------
951 Kbuild builds userspace programs only when told to do so.
964 (2) Use always-y
969 always-y := $(userprogs)
973 userprogs-always-y := binderfs_example
982 is compiled. This includes generated files such as host programs.
983 Kbuild knows targets listed in $(hostprogs), $(always-y), $(always-m),
984 $(always-), $(extra-y), $(extra-) and $(targets). They are all deleted
990 $(clean-files).
995 clean-files := crc32table.h
1002 $(no-clean-files) variable.
1004 Usually kbuild descends down in subdirectories due to ``obj-* := dir/``,
1011 subdir- := compressed
1016 Note 1: arch/$(SRCARCH)/Makefile cannot use ``subdir-``, because that file is
1018 ``subdir-``.
1020 Note 2: All directories listed in core-y, libs-y, drivers-y and net-y will
1044 - Additional prerequisites are specified in arch/$(SRCARCH)/Makefile
1047 init-* core* drivers-* net-* libs-* and build all targets.
1049 - The values of the above variables are expanded in arch/$(SRCARCH)/Makefile.
1053 The very first objects linked are listed in scripts/head-object-list.txt.
1055 6) Finally, the architecture-specific part does any required post processing
1058 - This includes building boot records
1059 - Preparing initrd images and the like
1062 ----------------------------------------------------
1073 KBUILD_LDFLAGS := -m elf_s390
1075 Note: ldflags-y can be used to further customise
1076 the flags used. See `Non-builtin vmlinux targets - extra-y`_.
1089 LDFLAGS_vmlinux := -e stext
1103 OBJCOPYFLAGS := -O binary
1115 Default value - see top level Makefile.
1122 KBUILD_AFLAGS += -m64 -mcpu=ultrasparc
1127 Default value - see top level Makefile.
1136 cflags-$(CONFIG_X86_32) := -march=i386
1137 cflags-$(CONFIG_X86_64) := -mcmodel=small
1138 KBUILD_CFLAGS += $(cflags-y)
1146 cflags-$(CONFIG_MPENTIUMII) += $(call cc-option,\
1147 -march=pentium2,-march=i686)
1149 # Disable unit-at-a-time mode ...
1150 KBUILD_CFLAGS += $(call cc-option,-fno-unit-at-a-time)
1160 Default value - see top level Makefile.
1166 Note that target specification file generation (for ``--target``)
1170 Assembler options specific for built-in
1178 $(KBUILD_AFLAGS_MODULE) is used to add arch-specific options that
1184 $(CC) options specific for built-in
1192 $(KBUILD_CFLAGS_MODULE) is used to add arch-specific options that
1198 $(RUSTC) options specific for built-in
1206 $(KBUILD_RUSTFLAGS_MODULE) is used to add arch-specific options that
1214 $(KBUILD_LDFLAGS_MODULE) is used to add arch-specific options
1220 The linker script with full path. Assigned by the top-level Makefile.
1226 The objects listed in scripts/head-object-list.txt are exceptions;
1235 --------------------------------
1244 --------------------------------
1259 See also chapter XXX-TODO that describes how kbuild supports
1263 -----------------------------------------
1267 corresponding arch-specific section for modules; the module-building
1268 machinery is all architecture-independent.
1270 core-y, libs-y, drivers-y
1271 $(libs-y) lists directories where a lib.a archive can be located.
1273 The rest list directories where a built-in.a object file can be
1278 $(core-y), $(libs-y), $(drivers-y)
1281 and arch/$(SRCARCH)/Makefile only adds architecture-specific
1287 core-y += arch/sparc/
1289 libs-y += arch/sparc/prom/
1290 libs-y += arch/sparc/lib/
1292 drivers-$(CONFIG_PM) += arch/sparc/power/
1294 Architecture-specific boot images
1295 ---------------------------------
1323 There are no rules for naming architecture-specific targets,
1331 echo '* bzImage - Compressed kernel image (arch/x86/boot/bzImage)'
1352 -----------------------------------------
1363 LDFLAGS_bootsect := -Ttext 0x0 -s --oformat binary
1364 LDFLAGS_setup := -Ttext 0x0 -s --oformat binary -e begtext
1372 LDFLAGS_$@ syntax - one for each potential target.
1400 $(obj)/vmlinux.bin.gz: $(vmlinux.bin.all-y) FORCE
1407 blob to non-init memory prior to calling unflatten_device_tree().
1409 To use this command, simply add ``*.dtb`` into obj-y or targets, or make
1417 targets += $(dtb-y)
1418 DTC_FLAGS ?= -p 1024
1421 ----------------------------
1429 kbuild knows .lds files and includes a rule ``*lds.S`` -> ``*lds``.
1434 extra-y := vmlinux.lds
1436 The assignment to extra-y is used to tell kbuild to build the
1444 KBUILD_CPPFLAGS : Set in top-level Makefile
1445 cppflags-y : May be set in the kbuild makefile
1446 CPPFLAGS_$(@F) : Target-specific flags.
1451 architecture-specific files.
1454 --------------------
1456 The directory include/asm-generic contains the header files
1462 See `generic-y`_ for further info on syntax etc.
1464 Post-link pass
1465 --------------
1468 will be invoked for post-link objects (vmlinux and modules.ko)
1469 for architectures to run post-link passes on. Must also handle
1475 .tmp_vmlinux? targets to be called from link-vmlinux.sh.
1484 Many headers can be exported as-is but other headers require a
1485 minimal pre-processing before they are ready for user-space.
1487 The pre-processing does:
1489 - drop kernel-specific annotations
1490 - drop include of compiler.h
1491 - drop all sections that are kernel internal (guarded by ``ifdef __KERNEL__``)
1498 arch/<arch>/include/asm/ to list asm files coming from asm-generic.
1502 no-export-headers
1503 -----------------
1505 no-export-headers is essentially used by include/uapi/linux/Kbuild to
1509 generic-y
1510 ---------
1513 include/asm-generic then this is listed in the file
1519 generic-y += termios.h
1520 generic-y += rtc.h
1537 #include <asm-generic/termios.h>
1539 generated-y
1540 -----------
1542 If an architecture generates other header files alongside generic-y
1543 wrappers, generated-y specifies them.
1545 This prevents them being treated as stale asm-generic wrappers and
1551 generated-y += syscalls_32.h
1553 mandatory-y
1554 -----------
1556 mandatory-y is essentially used by include/(uapi/)asm-generic/Kbuild
1559 This works like optional generic-y. If a mandatory header is missing
1561 generate a wrapper of the asm-generic one.
1574 three-part version number, such as "2", "4", and "0". These three
1577 $(EXTRAVERSION) defines an even tinier sublevel for pre-patches
1578 or additional patches. It is usually some non-numeric string
1579 such as "-pre4", and is often blank.
1582 $(KERNELRELEASE) is a single string such as "2.4.0-pre4", suitable
1602 both 32-bit and 64-bit.
1611 Use this for architecture-specific install targets.
1626 default option --strip-debug will be used. Otherwise, the
1644 GNU Make supports elementary list-processing functions. The kernel
1649 immediate evaluation of the right-hand side and stores an actual string
1650 into the left-hand side. ``=`` is like a formula definition; it stores the
1651 right-hand side in an unevaluated form and then evaluates this form each
1652 time the left-hand side is used.
1660 - Original version made by Michael Elizabeth Chastain, <mailto:mec@shout.net>
1661 - Updates by Kai Germaschewski <kai@tp1.ruhr-uni-bochum.de>
1662 - Updates by Sam Ravnborg <sam@ravnborg.org>
1663 - Language QA by Jan Engelhardt <jengelh@gmx.de>
1668 - Generating offset header files.
1669 - Add more variables to chapters 7 or 9?