xref: /freebsd/share/man/man7/build.7 (revision 75af1320f4b57fb568ec4f6df6171a0343953f4f)
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28.Dd November 13, 2024
29.Dt BUILD 7
30.Os
31.Sh NAME
32.Nm build
33.Nd general instructions on how to build the
34.Fx
35system
36.Sh DESCRIPTION
37The sources for the
38.Fx
39system and its applications are contained in three different directories,
40normally
41.Pa /usr/src ,
42.Pa /usr/doc ,
43and
44.Pa /usr/ports .
45These directories may be initially empty or non-existent until updated with
46Git
47.Po installed from packages with
48.Xr pkg 7
49or from
50.Xr ports 7 Pc .
51Directory
52.Pa /usr/src
53contains the
54.Dq "base system"
55sources, which is loosely defined as the things required to rebuild
56the system to a useful state.
57Directory
58.Pa /usr/doc
59contains the source for the system documentation, excluding the manual
60pages.
61Directory
62.Pa /usr/ports
63contains a tree that provides a consistent interface for building and
64installing third party applications.
65For more information about the ports build process, see
66.Xr ports 7 .
67.Pp
68The
69.Xr make 1
70command is used in each of these directories to build and install the
71things in that directory.
72Issuing the
73.Xr make 1
74command in any directory issues the
75.Xr make 1
76command recursively in all subdirectories.
77With no target specified, the items in the directories are built
78and no further action is taken.
79.Pp
80A source tree is allowed to be read-only.
81As described in
82.Xr make 1 ,
83objects are usually built in a separate object directory hierarchy
84specified by the environment variable
85.Va MAKEOBJDIRPREFIX ,
86or under
87.Pa /usr/obj
88if variable
89.Va MAKEOBJDIRPREFIX
90is not set.
91The canonical object directory is described in the documentation for the
92.Cm buildworld
93target below.
94.Pp
95The build may be controlled by defining
96.Xr make 1
97variables described in the
98.Sx ENVIRONMENT
99section below, and by the variables documented in
100.Xr make.conf 5 .
101.Pp
102The default components included in the build are specified in the file
103.Pa /etc/src.conf
104in the source tree.
105To override the default file, include the SRCCONF option in the make steps,
106pointing to a custom src.conf file.
107For more information see
108.Xr src.conf 5 .
109.Pp
110The following list provides the names and actions for the targets
111supported by the build system:
112.Bl -tag -width ".Cm cleandepend"
113.It Cm analyze
114Run Clang static analyzer against all objects and present output on stdout.
115.It Cm check
116Run tests for a given subdirectory.
117The default directory used is
118.Pa ${.OBJDIR} ,
119but the check directory can be changed with
120.Pa ${CHECKDIR} .
121.It Cm checkworld
122Run the
123.Fx
124test suite on installed world.
125.It Cm clean
126Remove any files created during the build process.
127.It Cm cleandepend
128Remove the
129.Pa ${.OBJDIR}/${DEPENDFILE}*
130files generated by prior
131.Dq Li "make"
132and
133.Dq Li "make depend"
134steps.
135.It Cm cleandir
136Remove the canonical object directory if it exists, or perform
137actions equivalent to
138.Dq Li "make clean cleandepend"
139if it does not.
140This target will also remove an
141.Pa obj
142link in
143.Pa ${.CURDIR}
144if that exists.
145.Pp
146It is advisable to run
147.Dq Li "make cleandir"
148twice: the first invocation will remove the canonical object directory
149and the second one will clean up
150.Pa ${.CURDIR} .
151.It Cm depend
152Generate a list of build dependencies in file
153.Pa ${.OBJDIR}/${DEPENDFILE} .
154Per-object dependencies are generated at build time and stored in
155.Pa ${.OBJDIR}/${DEPENDFILE}.${OBJ} .
156.It Cm install
157Install the results of the build to the appropriate location in the
158installation directory hierarchy specified in variable
159.Va DESTDIR .
160.It Cm obj
161Create the canonical object directory associated with the current
162directory.
163.It Cm objlink
164Create a symbolic link to the canonical object directory in
165.Pa ${.CURDIR} .
166.It Cm tags
167Generate a tags file using the program specified in the
168.Xr make 1
169variable
170.Va CTAGS .
171The build system supports
172.Xr ctags 1
173and
174.Nm "GNU Global" .
175.El
176.Pp
177The other supported targets under directory
178.Pa /usr/src
179are:
180.Bl -tag -width ".Cm distributeworld"
181.It Cm buildenv
182Spawn an interactive shell with environment variables set up for
183building the system or individual components.
184For cross-building the target architecture needs to be specified with
185.Xr make 1
186variables
187.Va TARGET_ARCH
188and
189.Va TARGET .
190.Pp
191This target is only useful after a complete toolchain (including
192the compiler, linker, assembler, headers and libraries) has been
193built; see the
194.Cm toolchain
195target below.
196.It Cm buildworld
197Build everything but the kernel, configure files in
198.Pa etc ,
199and
200.Pa release .
201The object directory can be changed from the default
202.Pa /usr/obj
203by setting the
204.Pa MAKEOBJDIRPREFIX
205.Xr make 1
206variable.
207The actual build location prefix used
208depends on the
209.Va WITH_UNIFIED_OBJDIR
210option from
211.Xr src.conf 5 .
212If enabled it is
213.Pa ${MAKEOBJDIRPREFIX}${.CURDIR}/${TARGET}.${TARGET_ARCH}
214for all builds.
215If disabled it is
216.Pa ${MAKEOBJDIRPREFIX}${.CURDIR}
217for native builds, and
218.Pa ${MAKEOBJDIRPREFIX}/${TARGET}.${TARGET_ARCH}${.CURDIR}
219for cross builds and native builds with variable
220.Va CROSS_BUILD_TESTING
221set.
222.It Cm cleankernel
223Attempts to clean up targets built by a preceding
224.Cm buildkernel ,
225or similar step, built from the same source directory and
226.Va KERNCONF .
227.It Cm cleanworld
228Attempt to clean up targets built by a preceding
229.Cm buildworld ,
230or similar step, built from this source directory.
231.It Cm cleanuniverse
232When
233.Va WITH_UNIFIED_OBJDIR
234is enabled, attempt to clean up targets built by a preceding
235.Cm buildworld ,
236.Cm universe ,
237or similar step, for any architecture built from this source directory.
238.It Cm distributeworld
239Distribute everything compiled by a preceding
240.Cm buildworld
241step.
242Files are placed in the directory hierarchy specified by
243.Xr make 1
244variable
245.Va DISTDIR .
246This target is used while building a release; see
247.Xr release 7 .
248.It Cm native-xtools
249This target builds a cross-toolchain for the given
250.Sy TARGET
251and
252.Sy TARGET_ARCH ,
253as well as a select list of static userland tools for the host system.
254This is intended to be used in a jail where QEMU is used to improve
255performance by avoiding emulating binaries that do not need to be emulated.
256.Sy TARGET
257and
258.Sy TARGET_ARCH
259should be defined.
260.It Cm native-xtools-install
261Installs the results to
262.Pa ${DESTDIR}/${NXTP}
263where
264.Va NXTP
265defaults to
266.Pa nxb-bin .
267.Sy TARGET
268and
269.Sy TARGET_ARCH
270must be defined.
271.It Cm packageworld
272Archive the results of
273.Cm distributeworld ,
274placing the results in
275.Va DISTDIR .
276This target is used while building a release; see
277.Xr release 7 .
278.It Cm installworld
279Install everything built by a preceding
280.Cm buildworld
281step into the directory hierarchy pointed to by
282.Xr make 1
283variable
284.Va DESTDIR .
285.Pp
286If installing onto an NFS file system and running
287.Xr make 1
288with the
289.Fl j
290option, make sure that
291.Xr rpc.lockd 8
292is running on both client and server.
293See
294.Xr rc.conf 5
295on how to make it start at boot time.
296.It Cm toolchain
297Create the build toolchain needed to build the rest of the system.
298For cross-architecture builds, this step creates a cross-toolchain.
299.It Cm universe
300For each architecture,
301execute a
302.Cm buildworld
303followed by a
304.Cm buildkernel
305for all kernels for that architecture,
306including
307.Pa LINT .
308This command takes a long time.
309.It Cm kernels
310Like
311.Cm universe
312with
313.Va WITHOUT_WORLDS
314defined so only the kernels for each architecture are built.
315.It Cm worlds
316Like
317.Cm universe
318with
319.Va WITHOUT_KERNELS
320defined so only the worlds for each architecture are built.
321.It Cm targets
322Print a list of supported
323.Va TARGET
324/
325.Va TARGET_ARCH
326pairs for world and kernel targets.
327.It Cm tinderbox
328Execute the same targets as
329.Cm universe .
330In addition print a summary of all failed targets at the end and
331exit with an error if there were any.
332.It Cm toolchains
333Create a build toolchain for each architecture supported by the build system.
334.It Cm xdev
335Builds and installs a cross-toolchain and sysroot for the given
336.Sy TARGET
337and
338.Sy TARGET_ARCH .
339The sysroot contains target library and headers.
340The target is an alias for
341.Cm xdev-build
342and
343.Cm xdev-install .
344The location of the files installed can be controlled with
345.Va DESTDIR .
346The target location in
347.Va DESTDIR
348is
349.Pa ${DESTDIR}/${XDTP}
350where
351.Va XDTP
352defaults to
353.Pa /usr/${XDDIR}
354and
355.Va XDDIR
356defaults to
357.Pa ${TARGET_ARCH}-freebsd .
358.It Cm xdev-build
359Builds for the
360.Cm xdev
361target.
362.It Cm xdev-install
363Installs the files for the
364.Cm xdev
365target.
366.It Cm xdev-links
367Installs autoconf-style symlinks to
368.Pa ${DESTDIR}/usr/bin
369pointing into the xdev toolchain in
370.Pa ${DESTDIR}/${XDTP} .
371.El
372.Pp
373Kernel specific build targets in
374.Pa /usr/src
375are:
376.Bl -tag -width ".Cm distributekernel"
377.It Cm buildkernel
378Rebuild the kernel and the kernel modules.
379The object directory can be changed from the default
380.Pa /usr/obj
381by setting the
382.Pa MAKEOBJDIRPREFIX
383.Xr make 1
384variable.
385.It Cm installkernel
386Install the kernel and the kernel modules to directory
387.Pa ${DESTDIR}/boot/kernel ,
388renaming any pre-existing directory with this name to
389.Pa kernel.old
390if it contained the currently running kernel.
391The target directory under
392.Pa ${DESTDIR}
393may be modified using the
394.Va INSTKERNNAME
395and
396.Va KODIR
397.Xr make 1
398variables.
399.It Cm distributekernel
400Install the kernel to the directory
401.Pa ${DISTDIR}/kernel/boot/kernel .
402This target is used while building a release; see
403.Xr release 7 .
404.It Cm packages
405Create a
406.Xr pkg 7
407repository containing packages that can be used to create or upgrade an
408installation of the base system.
409The output repository is placed in the object directory, under
410.Pa repo/${PKG_ABI}
411where
412.Va PKG_ABI
413is the
414.Xr pkg 7
415ABI for the build target, for example,
416.Pa /usr/obj/${SRCDIR}/repo/FreeBSD:15:amd64 .
417.It Cm packagekernel
418Archive the results of
419.Cm distributekernel ,
420placing the results in
421.Va DISTDIR .
422This target is used while building a release; see
423.Xr release 7 .
424.It Cm kernel
425Equivalent to
426.Cm buildkernel
427followed by
428.Cm installkernel
429.It Cm kernel-toolchain
430Rebuild the tools needed for kernel compilation.
431Use this if you did not do a
432.Cm buildworld
433first.
434.It Cm reinstallkernel
435Reinstall the kernel and the kernel modules, overwriting the contents
436of the target directory.
437As with the
438.Cm installkernel
439target, the target directory can be specified using the
440.Xr make 1
441variable
442.Va INSTKERNNAME .
443.El
444.Pp
445Convenience targets for cleaning up the install destination directory
446denoted by variable
447.Va DESTDIR
448include:
449.Bl -tag -width ".Cm delete-old-libs"
450.It Cm check-old
451Print a list of old files and directories in the system.
452.It Cm delete-old
453Delete obsolete base system files and directories interactively.
454When
455.Li -DBATCH_DELETE_OLD_FILES
456is specified at the command line, the delete operation will be
457non-interactive.
458The variables
459.Va DESTDIR ,
460.Va TARGET_ARCH
461and
462.Va TARGET
463should be set as with
464.Dq Li "make installworld" .
465.It Cm delete-old-libs
466Delete obsolete base system libraries interactively.
467This target should only be used if no third party software uses these
468libraries.
469When
470.Li -DBATCH_DELETE_OLD_FILES
471is specified at the command line, the delete operation will be
472non-interactive.
473The variables
474.Va DESTDIR ,
475.Va TARGET_ARCH
476and
477.Va TARGET
478should be set as with
479.Dq Li "make installworld" .
480.El
481.Sh ENVIRONMENT
482Variables that influence all builds include:
483.Bl -tag -width ".Va MAKEOBJDIRPREFIX"
484.It Va DEBUG_FLAGS
485Defines a set of debugging flags that will be used to build all userland
486binaries under
487.Pa /usr/src .
488When
489.Va DEBUG_FLAGS
490is defined, the
491.Cm install
492and
493.Cm installworld
494targets install binaries from the current
495.Va MAKEOBJDIRPREFIX
496without stripping,
497so that debugging information is retained in the installed binaries.
498.It Va DESTDIR
499The directory hierarchy prefix where built objects will be installed.
500If not set,
501.Va DESTDIR
502defaults to the empty string.
503.It Va MAKEOBJDIRPREFIX
504Defines the prefix for directory names in the tree of built objects.
505Defaults to
506.Pa /usr/obj
507if not defined.
508This variable should only be set in the environment or
509.Pa /etc/src-env.conf
510and not via
511.Pa /etc/make.conf
512or
513.Pa /etc/src.conf
514or the command line.
515.Va MAKEOBJDIRPREFIX
516must specify an absolute path.
517.It Va WITHOUT_WERROR
518If defined, compiler warnings will not cause the build to halt,
519even if the makefile says otherwise.
520.It Va WITH_CTF
521If defined, the build process will run the DTrace CTF conversion
522tools on built objects.
523.El
524.Pp
525Additionally, builds in
526.Pa /usr/src
527are influenced by the following
528.Xr make 1
529variables:
530.Bl -tag -width ".Va LOCAL_MODULES_DIR"
531.It Va CROSS_TOOLCHAIN
532Requests use of an external toolchain to build either the world or kernel.
533This value of this variable can either be the full path to a file,
534or the base name of a file in
535.Pa ${LOCALBASE}/share/toolchains .
536The file should be a make file which sets variables to request an external
537toolchain such as
538.Va XCC .
539.Pp
540External toolchains are available in ports for both LLVM and GCC/binutils.
541For external toolchains available in ports,
542.Va CROSS_TOOLCHAIN
543should be set to the name of the package.
544LLVM toolchain packages use the name llvm<major version>.
545GCC toolchains provide separate packages for each architecture and use the
546name ${MACHINE_ARCH}-gcc<major version>.
547.It Va KERNCONF
548Overrides which kernel to build and install for the various kernel
549make targets.
550It defaults to
551.Cm GENERIC .
552.It Va KERNCONFDIR
553Overrides the directory in which
554.Va KERNCONF
555and any files included by
556.Va KERNCONF
557should be found.
558Defaults to
559.Pa sys/${ARCH}/conf .
560.It Va KERNFAST
561If set, the build target
562.Cm buildkernel
563defaults to setting
564.Va NO_KERNELCLEAN ,
565.Va NO_KERNELCONFIG ,
566and
567.Va NO_KERNELOBJ .
568When set to a value other than
569.Cm 1
570then
571.Va KERNCONF
572is set to the value of
573.Va KERNFAST .
574.It Va LOCAL_DIRS
575If set, this variable supplies a list of additional directories relative to
576the root of the source tree to build as part of the
577.Cm everything
578target.
579The directories are built in parallel with each other,
580and with the base system directories.
581Insert a
582.Va .WAIT
583directive at the beginning of the
584.Va LOCAL_DIRS
585list to ensure all base system directories are built first.
586.Va .WAIT
587may also be used as needed elsewhere within the list.
588.It Va LOCAL_ITOOLS
589If set, this variable supplies a list of additional tools that are used by the
590.Cm installworld
591and
592.Cm distributeworld
593targets.
594.It Va LOCAL_LIB_DIRS
595If set, this variable supplies a list of additional directories relative to
596the root of the source tree to build as part of the
597.Cm libraries
598target.
599The directories are built in parallel with each other,
600and with the base system libraries.
601Insert a
602.Va .WAIT
603directive at the beginning of the
604.Va LOCAL_DIRS
605list to ensure all base system libraries are built first.
606.Va .WAIT
607may also be used as needed elsewhere within the list.
608.It Va LOCAL_MTREE
609If set, this variable supplies a list of additional mtrees relative to the
610root of the source tree to use as part of the
611.Cm hierarchy
612target.
613.It Va LOCAL_LEGACY_DIRS
614If set, this variable supplies a list of additional directories relative to
615the root of the source tree to build as part of the
616.Cm legacy
617target.
618.It Va LOCAL_BSTOOL_DIRS
619If set, this variable supplies a list of additional directories relative to
620the root of the source tree to build as part of the
621.Cm bootstrap-tools
622target.
623.It Va LOCAL_TOOL_DIRS
624If set, this variable supplies a list of additional directories relative to
625the root of the source tree to build as part of the
626.Cm build-tools
627target.
628.It Va LOCAL_XTOOL_DIRS
629If set, this variable supplies a list of additional directories relative to
630the root of the source tree to build as part of the
631.Cm cross-tools
632target.
633.It Va PORTS_MODULES
634A list of ports with kernel modules that should be built and installed
635as part of the
636.Cm buildkernel
637and
638.Cm installkernel
639process.
640.Bd -literal -offset indent
641make PORTS_MODULES=emulators/virtualbox-ose-kmod kernel
642.Ed
643.It Va LOCAL_MODULES
644A list of external kernel modules that should be built and installed
645as part of the
646.Cm buildkernel
647and
648.Cm installkernel
649process.
650Defaults to the list of sub-directories of
651.Va LOCAL_MODULES_DIR .
652.It Va LOCAL_MODULES_DIR
653The directory in which to search for the kernel modules specified by
654.Va LOCAL_MODULES .
655Each kernel module should consist of a directory containing a makefile.
656Defaults to
657.Pa ${LOCALBASE}/sys/modules .
658.It Va SRCCONF
659Specify a file to override the default
660.Pa /etc/src.conf .
661The src.conf file controls the components to build.
662See
663.Xr src.conf 5
664.It Va STRIPBIN
665Command to use at install time when stripping binaries.
666Be sure to add any additional tools required to run
667.Va STRIPBIN
668to the
669.Va LOCAL_ITOOLS
670.Xr make 1
671variable before running the
672.Cm distributeworld
673or
674.Cm installworld
675targets.
676See
677.Xr install 1
678for more details.
679.It Va SUBDIR_OVERRIDE
680Override the default list of sub-directories and only build the
681sub-directory named in this variable.
682If combined with
683.Cm buildworld
684then all libraries and includes, and some of the build tools will still build
685as well.
686Specifying
687.Cm -DNO_LIBS ,
688and
689.Cm -DWORLDFAST
690will only build the specified directory as was done historically.
691When combined with
692.Cm buildworld
693it is necessary to override
694.Va LOCAL_LIB_DIRS
695with any custom directories containing libraries.
696This allows building a subset of the system in the same way as
697.Cm buildworld
698does using its sysroot handling.
699This variable can also be useful when debugging failed builds.
700.Bd -literal -offset indent
701make some-target SUBDIR_OVERRIDE=foo/bar
702.Ed
703.It Va SYSDIR
704Specify the location of the kernel source to override the default
705.Pa /usr/src/sys .
706The kernel source is located in the
707.Pa sys
708subdirectory of the source tree checked out from the
709.Pa src.git
710repository.
711.It Va TARGET
712The target hardware platform.
713This is analogous to the
714.Dq Nm uname Fl m
715output.
716This is necessary to cross-build some target architectures.
717For example, cross-building for ARM64 machines requires
718.Va TARGET_ARCH Ns = Ns Li aarch64
719and
720.Va TARGET Ns = Ns Li arm64 .
721If not set,
722.Va TARGET
723defaults to the current hardware platform, unless
724.Va TARGET_ARCH
725is also set, in which case it defaults to the appropriate
726value for that architecture.
727.It Va TARGET_ARCH
728The target machine processor architecture.
729This is analogous to the
730.Dq Nm uname Fl p
731output.
732Set this to cross-build for a different architecture.
733If not set,
734.Va TARGET_ARCH
735defaults to the current machine architecture, unless
736.Va TARGET
737is also set, in which case it defaults to the appropriate
738value for that platform.
739Typically, one only needs to set
740.Va TARGET .
741.El
742.Pp
743Builds under directory
744.Pa /usr/src
745are also influenced by defining one or more of the following symbols,
746using the
747.Fl D
748option of
749.Xr make 1 :
750.Bl -tag -width ".Va LOADER_DEFAULT_INTERP"
751.It Va LOADER_DEFAULT_INTERP
752Defines what interpreter the default loader program will have.
753Valid values include
754.Dq 4th ,
755.Dq lua ,
756and
757.Dq simp .
758This creates the default link for
759.Pa /boot/loader
760to the loader with that interpreter.
761It also determines what interpreter is compiled into
762.Pa userboot .
763.It Va NO_CLEANDIR
764If set, the build targets that clean parts of the object tree use the
765equivalent of
766.Dq make clean
767instead of
768.Dq make cleandir .
769.It Va NO_CLEAN
770If set, no object tree files are cleaned at all.
771This is the default when
772.Va WITH_META_MODE
773is used with
774.Xr filemon 4
775loaded.
776See
777.Xr src.conf 5
778for more details.
779Setting
780.Va NO_CLEAN
781implies
782.Va NO_KERNELCLEAN ,
783so when
784.Va NO_CLEAN
785is set no kernel objects are cleaned either.
786.It Va NO_CTF
787If set, the build process does not run the DTrace CTF conversion tools
788on built objects.
789.It Va NO_SHARE
790If set, the build does not descend into the
791.Pa /usr/src/share
792subdirectory (i.e., manual pages, locale data files, timezone data files and
793other
794.Pa /usr/src/share
795files will not be rebuild from their sources).
796.It Va NO_KERNELCLEAN
797If set, the build process does not run
798.Dq make clean
799as part of the
800.Cm buildkernel
801target.
802.It Va NO_KERNELCONFIG
803If set, the build process does not run
804.Xr config 8
805as part of the
806.Cm buildkernel
807target.
808.It Va NO_KERNELOBJ
809If set, the build process does not run
810.Dq make obj
811as part of the
812.Cm buildkernel
813target.
814.It Va NO_LIBS
815If set, the libraries phase will be skipped.
816.It Va NO_OBJWALK
817If set, no object directories will be created.
818This should only be used if object directories were created in a
819previous build and no new directories are connected.
820.It Va UNIVERSE_TOOLCHAIN
821Requests use of the toolchain built as part of the
822.Cm universe
823target as an external toolchain.
824.It Va WORLDFAST
825If set, the build target
826.Cm buildworld
827defaults to setting
828.Va NO_CLEAN ,
829.Va NO_OBJWALK ,
830and will skip most bootstrap phases.
831It will only bootstrap libraries and build all of userland.
832This option should be used only when it is known that none of the bootstrap
833needs changed and that no new directories have been connected to the build.
834.El
835.Pp
836Builds under directory
837.Pa /usr/doc
838are influenced by the following
839.Xr make 1
840variables:
841.Bl -tag -width ".Va DOC_LANG"
842.It Va DOC_LANG
843If set, restricts the documentation build to the language subdirectories
844specified as its content.
845The default action is to build documentation for all languages.
846.El
847.Pp
848Builds using the
849.Cm universe
850and related targets are influenced by the following
851.Xr make 1
852variables:
853.Bl -tag -width ".Va USE_GCC_TOOLCHAINS"
854.It Va JFLAG
855Pass the value of this variable to each
856.Xr make 1
857invocation used to build worlds and kernels.
858This can be used to enable multiple jobs within a single architecture's build
859while still building each architecture serially.
860.It Va MAKE_JUST_KERNELS
861Only build kernels for each supported architecture.
862.It Va MAKE_JUST_WORLDS
863Only build worlds for each supported architecture.
864.It Va WITHOUT_WORLDS
865Only build kernels for each supported architecture.
866.It Va WITHOUT_KERNELS
867Only build worlds for each supported architecture.
868.It Va UNIVERSE_TARGET
869Execute the specified
870.Xr make 1
871target for each supported architecture instead of the default action of
872building a world and one or more kernels.
873This variable implies
874.Va WITHOUT_KERNELS .
875.It Va USE_GCC_TOOLCHAINS
876Use external GCC toolchains to build the requested targets.
877If the required toolchain package for a supported architecture is not installed,
878the build for that architecture is skipped.
879.It Va TARGETS
880Only build the listed targets instead of each supported architecture.
881.It Va EXTRA_TARGETS
882In addition to the supported architectures, build the semi-supported
883architectures.
884A semi-supported architecture has build support in the
885.Fx
886tree, but receives significantly less testing and is generally for
887fringe uses that do not have a wide appeal.
888.El
889.Sh FILES
890.Bl -tag -width ".Pa /usr/share/examples/etc/make.conf" -compact
891.It Pa /usr/doc/Makefile
892.It Pa /usr/doc/share/mk/doc.project.mk
893.It Pa /usr/ports/Mk/bsd.port.mk
894.It Pa /usr/ports/Mk/bsd.sites.mk
895.It Pa /usr/share/examples/etc/make.conf
896.It Pa /usr/src/Makefile
897.It Pa /usr/src/Makefile.inc1
898.El
899.Sh EXAMPLES
900For an
901.Dq approved
902method of updating your system from the latest sources, please see the
903.Sx COMMON ITEMS
904section in
905.Pa src/UPDATING .
906.Pp
907The following sequence of commands can be used to cross-build the system for
908the arm64 (aarch64) architecture on a different host architecture, such as
909amd64:
910.Bd -literal -offset indent
911cd /usr/src
912make TARGET=arm64 buildworld buildkernel
913make TARGET=arm64 DESTDIR=/clients/arm64 installworld installkernel
914.Ed
915.Sh SEE ALSO
916.Xr cc 1 ,
917.Xr install 1 ,
918.Xr make 1 ,
919.Xr make.conf 5 ,
920.Xr src.conf 5 ,
921.Xr arch 7 ,
922.Xr development 7 ,
923.Xr pkg 7 ,
924.Xr ports 7 ,
925.Xr release 7 ,
926.Xr tests 7 ,
927.Xr config 8 ,
928.Xr etcupdate 8 ,
929.Xr reboot 8 ,
930.Xr shutdown 8
931.Sh HISTORY
932The
933.Nm
934manpage first appeared in
935.Fx 4.3 .
936.Sh AUTHORS
937.An Mike W. Meyer Aq Mt mwm@mired.org
938