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BUILD(7) Miscellaneous Information Manual BUILD(7) NAME build -- general instructions on how to build the FreeBSD system DESCRIPTION The sources for the FreeBSD system and its applications are contained in three directories, normally: /usr/src "base system", loosely defined as everything required to build the system to a useful state /usr/doc system documentation, excluding manual pages /usr/ports third-party software, with a consistent interface for building and installing them; see ports(7) These directories may be initially empty or non-existent until updated with Git (devel/git from the FreeBSD Ports Collection). The make(1) command is used in each of these directories to build and install the things in that directory. Issuing the make(1) command in any directory issues the make(1) command recursively in all subdirecto- ries. With no target specified, the items in the directories are built and no further action is taken. A source tree is allowed to be read-only. As described in make(1), ob- jects are usually built in a separate object directory hierarchy speci- fied by the environment variable MAKEOBJDIRPREFIX, or under /usr/obj if variable MAKEOBJDIRPREFIX is not set. The canonical object directory is described in the documentation for the buildworld target below. The build may be controlled by defining make(1) variables described in the "ENVIRONMENT" section below, and by the variables documented in make.conf(5). The default components included in the build are specified in the file /etc/src.conf in the source tree. To override the default file, in- clude the SRCCONF option in the make steps, pointing to a custom src.conf file. For more information see src.conf(5). The following list provides the names and actions for the targets sup- ported by the build system: analyze Run Clang static analyzer against all objects and present output on stdout. check Run tests for a given subdirectory. The default directory used is ${.OBJDIR}, but the check directory can be changed with ${CHECKDIR}. checkworld Run the FreeBSD test suite on installed world. clean Remove any files created during the build process. cleandepend Remove the ${.OBJDIR}/${DEPENDFILE}* files generated by prior "make" and "make depend" steps. cleandir Remove the canonical object directory if it exists, or perform actions equivalent to "make clean cleandepend" if it does not. This target will also remove an obj link in ${.CURDIR} if that exists. It is advisable to run "make cleandir" twice: the first invocation will remove the canonical object directory and the second one will clean up ${.CURDIR}. depend Generate a list of build dependencies in file ${.OBJDIR}/${DEPENDFILE}. Per-object dependencies are generated at build time and stored in ${.OBJDIR}/${DEPENDFILE}.${OBJ}. install Install the results of the build to the appropriate loca- tion in the installation directory hierarchy specified in variable DESTDIR. obj Create the canonical object directory associated with the current directory. objlink Create a symbolic link to the canonical object directory in ${.CURDIR}. tags Generate a tags file using the program specified in the make(1) variable CTAGS. The build system supports ctags(1) and GNU Global. The other supported targets under directory /usr/src are: buildenv Spawn an interactive shell with environment variables set up for building the system or individual compo- nents. For cross-building the target architecture needs to be specified with make(1) variables TARGET_ARCH and TARGET. This target is only useful after a complete toolchain (including the compiler, linker, assembler, headers and libraries) has been built; see the toolchain tar- get below. buildworld Build everything but the kernel, configure files in etc, and release. The object directory can be changed from the default /usr/obj by setting the MAKEOBJDIRPREFIX make(1) variable. The actual build location prefix used depends on the WITH_UNIFIED_OBJDIR option from src.conf(5). If en- abled it is ${MAKEOBJDIRPREFIX}${.CURDIR}/${TARGET}.${TARGET_ARCH} for all builds. If disabled it is ${MAKEOBJDIRPREFIX}${.CURDIR} for native builds, and ${MAKEOBJDIRPREFIX}/${TARGET}.${TARGET_ARCH}${.CURDIR} for cross builds and native builds with variable CROSS_BUILD_TESTING set. cleankernel Attempts to clean up targets built by a preceding buildkernel, or similar step, built from the same source directory and KERNCONF. cleanworld Attempt to clean up targets built by a preceding buildworld, or similar step, built from this source directory. cleanuniverse When WITH_UNIFIED_OBJDIR is enabled, attempt to clean up targets built by a preceding buildworld, universe, or similar step, for any architecture built from this source directory. distributeworld Distribute everything compiled by a preceding buildworld step. Files are placed in the directory hierarchy specified by make(1) variable DISTDIR. This target is used while building a release; see release(7). native-xtools This target builds a cross-toolchain for the given TARGET and TARGET_ARCH, as well as a select list of static userland tools for the host system. This is intended to be used in a jail where QEMU is used to improve performance by avoiding emulating binaries that do not need to be emulated. TARGET and TARGET_ARCH should be defined. native-xtools-install Installs the results to ${DESTDIR}/${NXTP} where NXTP defaults to nxb-bin. TARGET and TARGET_ARCH must be defined. packages Create a freebsd-base(7) package repository containing packages that can be used to install or upgrade the base system. The repository is created in the object directory, under ${REPODIR}/${PKG_ABI} where REPODIR is the base directory where the repository will be created, and PKG_ABI is the pkg(7) ABI for the build target, for example, /usr/obj/${SRCDIR}/repo/FreeBSD:15:amd64. packageworld Archive the results of distributeworld, placing the results in DISTDIR. This target is used while build- ing a release(7) and is unrelated to building freebsd-base(7) packages. installworld Install everything built by a preceding buildworld step into the directory hierarchy pointed to by make(1) variable DESTDIR. If installing onto an NFS file system and running make(1) with the -j option, make sure that rpc.lockd(8) is running on both client and server. See rc.conf(5) on how to make it start at boot time. toolchain Create the build toolchain needed to build the rest of the system. For cross-architecture builds, this step creates a cross-toolchain. universe For each architecture, execute a buildworld followed by a buildkernel for all kernels for that architec- ture, including LINT. This command takes a long time. kernels Like universe with WITHOUT_WORLDS defined so only the kernels for each architecture are built. worlds Like universe with WITHOUT_KERNELS defined so only the worlds for each architecture are built. targets Print a list of supported TARGET / TARGET_ARCH pairs for world and kernel targets. tinderbox Execute the same targets as universe. In addition print a summary of all failed targets at the end and exit with an error if there were any. toolchains Create a build toolchain for each architecture sup- ported by the build system. xdev Builds and installs a cross-toolchain and sysroot for the given TARGET and TARGET_ARCH. The sysroot con- tains target library and headers. The target is an alias for xdev-build and xdev-install. The location of the files installed can be controlled with DESTDIR. The target location in DESTDIR is ${DESTDIR}/${XDTP} where XDTP defaults to /usr/${XDDIR} and XDDIR de- faults to ${TARGET_ARCH}-freebsd. update-packages Create or update the freebsd-base(7) package reposi- tory for the base system. If an old repository is be- ing updated, then packages whose contents have not changed since the previous version will be copied into the new repository to avoid needless updating of the version number. xdev-build Builds for the xdev target. xdev-install Installs the files for the xdev target. xdev-links Installs autoconf-style symlinks to ${DESTDIR}/usr/bin pointing into the xdev toolchain in ${DESTDIR}/${XDTP}. Kernel specific build targets in /usr/src are: buildkernel Rebuild the kernel and the kernel modules. The ob- ject directory can be changed from the default /usr/obj by setting the MAKEOBJDIRPREFIX make(1) variable. installkernel Install the kernel and the kernel modules to direc- tory ${DESTDIR}/boot/kernel, renaming any pre-exist- ing directory with this name to kernel.old if it con- tained the currently running kernel. The target di- rectory under ${DESTDIR} may be modified using the INSTKERNNAME or KODIR make(1) variables. distributekernel Install the kernel to the directory ${DISTDIR}/kernel/boot/kernel. This target is used while building a release; see release(7). packagekernel Archive the results of distributekernel, placing the results in DISTDIR. This target is used while build- ing a release(7) and is unrelated to building freebsd-base(7) packages. kernel Equivalent to buildkernel followed by installkernel kernel-toolchain Rebuild the tools needed for kernel compilation. Use this if you did not do a buildworld first. reinstallkernel Reinstall the kernel and the kernel modules, over- writing the contents of the target directory. As with the installkernel target, the target directory can be specified using the make(1) variable INSTKERNNAME. Convenience targets for cleaning up the install destination directory denoted by variable DESTDIR include: check-old Print a list of old files and directories in the sys- tem. check-old-libs Print a list of obsolete base system libraries. delete-old Delete obsolete base system files and directories in- teractively. When -DBATCH_DELETE_OLD_FILES is speci- fied at the command line, the delete operation will be non-interactive. The variables DESTDIR, TARGET_ARCH and TARGET should be set as with "make installworld". delete-old-libs Delete obsolete base system libraries interactively. This target should only be used if no third party software uses these libraries. When -DBATCH_DELETE_OLD_FILES is specified at the command line, the delete operation will be non-interactive. The variables DESTDIR, TARGET_ARCH and TARGET should be set as with "make installworld". ENVIRONMENT Variables that influence all builds include: DEBUG_FLAGS Defines a set of debugging flags that will be used to build all userland binaries under /usr/src. When DEBUG_FLAGS is defined, the install and installworld targets install binaries from the current MAKEOBJDIRPREFIX without stripping, so that debugging information is retained in the installed binaries. DESTDIR The directory hierarchy prefix where built objects will be installed. If not set, DESTDIR defaults to the empty string. If set, DESTDIR must specify an absolute path. MAKEOBJDIRPREFIX Defines the prefix for directory names in the tree of built objects. Defaults to /usr/obj if not defined. This variable should only be set in the environment or /etc/src-env.conf and not via /etc/make.conf or /etc/src.conf or the command line. MAKEOBJDIRPREFIX must specify an absolute path. WITHOUT_WERROR If defined, compiler warnings will not cause the build to halt, even if the makefile says otherwise. WITH_CTF If defined, the build process will run the DTrace CTF conversion tools on built objects. Additionally, builds in /usr/src are influenced by the following make(1) variables: CROSS_TOOLCHAIN Requests use of an external toolchain to build ei- ther the world or kernel. This value of this vari- able can either be the full path to a file, or the base name of a file in ${LOCALBASE}/share/toolchains. The file should be a make file which sets variables to request an exter- nal toolchain such as XCC. External toolchains are available in ports for both LLVM and GCC/binutils. For external toolchains available in ports, CROSS_TOOLCHAIN should be set to the name of the package. LLVM toolchain packages use the name llvm<major version>. GCC toolchains provide separate packages for each architecture and use the name ${MACHINE_ARCH}-gcc<major version>. INSTKERNNAME If set, specify an alternative name to build and in- stall for the various kernel make targets. KERNCONF Overrides which kernel to build and install for the various kernel make targets. It defaults to GENERIC. KERNBUILDDIR Overrides the default directory to get all the opt_*.h files for building a kernel module. Useful for stand-alone modules that depend on config(8) op- tions. Automatically set for modules built with a kernel. KERNCONFDIR Overrides the directory in which KERNCONF and any files included by KERNCONF should be found. De- faults to sys/${ARCH}/conf. KERNFAST If set, the build target buildkernel defaults to setting NO_KERNELCLEAN, NO_KERNELCONFIG, and NO_KERNELOBJ. When set to a value other than 1 then KERNCONF is set to the value of KERNFAST. KODIR If set, this variable specifies an alternative di- rectory to install the kernel. LOCAL_DIRS If set, this variable supplies a list of additional directories relative to the root of the source tree to build as part of the everything target. The di- rectories are built in parallel with each other, and with the base system directories. Insert a .WAIT directive at the beginning of the LOCAL_DIRS list to ensure all base system directories are built first. .WAIT may also be used as needed elsewhere within the list. LOCAL_ITOOLS If set, this variable supplies a list of additional tools that are used by the installworld and distributeworld targets. LOCAL_LIB_DIRS If set, this variable supplies a list of additional directories relative to the root of the source tree to build as part of the libraries target. The di- rectories are built in parallel with each other, and with the base system libraries. Insert a .WAIT di- rective at the beginning of the LOCAL_DIRS list to ensure all base system libraries are built first. .WAIT may also be used as needed elsewhere within the list. LOCAL_MTREE If set, this variable supplies a list of additional mtrees relative to the root of the source tree to use as part of the hierarchy target. LOCAL_LEGACY_DIRS If set, this variable supplies a list of additional directories relative to the root of the source tree to build as part of the legacy target. LOCAL_BSTOOL_DIRS If set, this variable supplies a list of additional directories relative to the root of the source tree to build as part of the bootstrap-tools target. LOCAL_TOOL_DIRS If set, this variable supplies a list of additional directories relative to the root of the source tree to build as part of the build-tools target. LOCAL_XTOOL_DIRS If set, this variable supplies a list of additional directories relative to the root of the source tree to build as part of the cross-tools target. OBJROOT The object directory root is defined as ${OBJDIR}/${SRCDIR}/. See share/mk/src.sys.obj.mk. PKG_FORMAT Specify a package compression format when building freebsd-base(7) packages. Default: `tzst'. Con- sider using `tar' to disable compression. Accepted options are documented in the -f description of pkg-create(8). PORTS_MODULES A list of ports with kernel modules that should be built and installed as part of the buildkernel and installkernel process. This is currently incompati- ble with building freebsd-base(7) packages. Each port must be specified as category/port[@flavor], e.g. PORTS_MODULES=graphics/gpu-firmware-intel-kmod@kabylake PORTS_MODULES+=graphics/drm-66-kmod LOCAL_MODULES A list of external kernel modules that should be built and installed as part of the buildkernel and installkernel process. Defaults to the list of sub- directories of LOCAL_MODULES_DIR. LOCAL_MODULES_DIR The directory in which to search for the kernel mod- ules specified by LOCAL_MODULES. Each kernel module should consist of a directory containing a makefile. Defaults to ${LOCALBASE}/sys/modules. SRCCONF Specify a file to override the default /etc/src.conf. The src.conf file controls the com- ponents to build. See src.conf(5) REPODIR The root directory used to create the package repos- itory for building packges(7). Defaults to ${OBJROOT}/repo/. This can also be set in src-env.conf(5). STRIPBIN Command to use at install time when stripping bina- ries. Be sure to add any additional tools required to run STRIPBIN to the LOCAL_ITOOLS make(1) variable before running the distributeworld or installworld targets. See install(1) for more details. SUBDIR_OVERRIDE Override the default list of sub-directories and only build the sub-directory named in this variable. If combined with buildworld then all libraries and includes, and some of the build tools will still build as well. Specifying -DNO_LIBS, and -DWORLDFAST will only build the specified directory as was done historically. When combined with buildworld it is necessary to override LOCAL_LIB_DIRS with any custom directories contain- ing libraries. This allows building a subset of the system in the same way as buildworld does using its sysroot handling. This variable can also be useful when debugging failed builds. make some-target SUBDIR_OVERRIDE=foo/bar SYSDIR Specify the location of the kernel source to over- ride the default /usr/src/sys. The kernel source is located in the sys subdirectory of the source tree checked out from the src.git repository. TARGET The target hardware platform. This is analogous to the "uname -m" output. This is necessary to cross- build some target architectures. For example, cross-building for ARM64 machines requires TARGET_ARCH=aarch64 and TARGET=arm64. If not set, TARGET defaults to the current hardware platform, unless TARGET_ARCH is also set, in which case it de- faults to the appropriate value for that architec- ture. TARGET_ARCH The target machine processor architecture. This is analogous to the "uname -p" output. Set this to cross-build for a different architecture. If not set, TARGET_ARCH defaults to the current machine ar- chitecture, unless TARGET is also set, in which case it defaults to the appropriate value for that plat- form. Typically, one only needs to set TARGET. Builds under directory /usr/src are also influenced by defining one or more of the following symbols, using the -D option of make(1): LOADER_DEFAULT_INTERP Defines what interpreter the default loader pro- gram will have. Valid values include "4th", "lua", and "simp". This creates the default link for /boot/loader to the loader with that interpreter. It also determines what inter- preter is compiled into userboot. NO_CLEANDIR If set, the build targets that clean parts of the object tree use the equivalent of "make clean" instead of "make cleandir". NO_CLEAN If set, no object tree files are cleaned at all. This is the default when WITH_META_MODE is used with filemon(4) loaded. See src.conf(5) for more details. Setting NO_CLEAN implies NO_KERNELCLEAN, so when NO_CLEAN is set no ker- nel objects are cleaned either. NO_CTF If set, the build process does not run the DTrace CTF conversion tools on built objects. NO_SHARE If set, the build does not descend into the /usr/src/share subdirectory (i.e., manual pages, locale data files, timezone data files and other /usr/src/share files will not be rebuild from their sources). NO_KERNELCLEAN If set, the build process does not run "make clean" as part of the buildkernel target. NO_KERNELCONFIG If set, the build process does not run config(8) as part of the buildkernel target. NO_KERNELOBJ If set, the build process does not run "make obj" as part of the buildkernel target. NO_LIBS If set, the libraries phase will be skipped. NO_OBJWALK If set, no object directories will be created. This should only be used if object directories were created in a previous build and no new di- rectories are connected. UNIVERSE_TOOLCHAIN Requests use of the toolchain built as part of the universe target as an external toolchain. WORLDFAST If set, the build target buildworld defaults to setting NO_CLEAN, NO_OBJWALK, and will skip most bootstrap phases. It will only bootstrap li- braries and build all of userland. This option should be used only when it is known that none of the bootstrap needs changed and that no new directories have been connected to the build. Builds under directory /usr/doc are influenced by the following make(1) variables: DOC_LANG If set, restricts the documentation build to the language subdirectories specified as its content. The default action is to build documentation for all languages. Builds using the universe and related targets are influenced by the following make(1) variables: JFLAG Pass the value of this variable to each make(1) in- vocation used to build worlds and kernels. This can be used to enable multiple jobs within a single architecture's build while still building each ar- chitecture serially. MAKE_JUST_KERNELS Only build kernels for each supported architecture. MAKE_JUST_WORLDS Only build worlds for each supported architecture. WITHOUT_WORLDS Only build kernels for each supported architecture. WITHOUT_KERNELS Only build worlds for each supported architecture. UNIVERSE_TARGET Execute the specified make(1) target for each sup- ported architecture instead of the default action of building a world and one or more kernels. This variable implies WITHOUT_KERNELS. USE_GCC_TOOLCHAINS Use external GCC toolchains to build the requested targets. If the required toolchain package for a supported architecture is not installed, the build for that architecture is skipped. A specific version of GCC can be used by setting the value of this variable to the desired version (for example, "gcc14"); otherwise a default version of GCC is used. TARGETS Only build the listed targets instead of each sup- ported architecture. EXTRA_TARGETS In addition to the supported architectures, build the semi-supported architectures. A semi-supported architecture has build support in the FreeBSD tree, but receives significantly less testing and is gen- erally for fringe uses that do not have a wide ap- peal. FILES /usr/doc/Makefile /usr/doc/share/mk/doc.project.mk /usr/ports/Mk/bsd.port.mk /usr/ports/Mk/bsd.sites.mk /usr/src/Makefile /usr/src/Makefile.inc1 make(1) infrastructure for each tree /usr/ports/UPDATING /usr/src/UPDATING notable changes in each tree /usr/share/examples/etc/make.conf example make.conf(5) /etc/src.conf src build configuration, see src.conf(5) EXAMPLES This section describes best practices for common situations. When man- ual intervention is necessary, it will be mentioned in UPDATING. Make sure you have full backups before proceeding! Example 1: Build and upgrade system in place If using installed drivers such as graphics or virtual machine guest drivers, check out the ports(7) tree, and specify the drivers in src.conf(5) so they are built and installed automatically after the kernel: git clone https://git.FreeBSD.org/ports.git /usr/ports cat << EOF >> /etc/src.conf PORTS_MODULES+=graphics/drm-kmod emulators/virtualbox-ose-kmod EOF Check out the CURRENT branch, build it, and install, overwriting the current system: git clone https://git.FreeBSD.org/src.git /usr/src cd /usr/src make buildworld buildkernel make installkernel shutdown -r now For major version upgrades, boot into single-user mode. After restart- ing, install userspace, and merge configurations. After verifying that you do not need them, delete old files and libraries: cd /usr/src etcupdate -p make installworld etcupdate -B make delete-old delete-old-libs shutdown -r now Example 2: Build and upgrade a custom kernel in place Create a custom kernel configuration, MYKERNEL, by including an exist- ing configuration and using device/nodevice and options/nooption to se- lect and configure components: cd /usr/src cat << EOF > sys/amd64/conf/MYKERNEL include GENERIC ident MYKERNEL nodevice sound EOF After creating the new kernel configuration, build a fresh toolchain, build the kernel, and install it, moving the old kernel to /boot/kernel.old/: make kernel-toolchain make -DALWAYS_CHECK_MAKE buildkernel KERNCONF=MYKERNEL make -DALWAYS_CHECK_MAKE installkernel KERNCONF=MYKERNEL shutdown -r now To build the kernel to an alternate location, use the INSTKERNNAME variable and boot it once to test via nextboot(8): make installkernel KERNCONF=MYKERNEL INSTKERNNAME=testkernel nextboot -k testkernel shutdown -r now Example 3: Build and upgrade a single piece of userspace Rebuild and reinstall a single piece of userspace, in this case ls(1): cd /usr/src/bin/ls make clean all make install Example 4: Build and upgrade a loadable kernel module Rebuild and reinstall a single loadable kernel module, in this case sound(4): cd /usr/src/sys/modules/sound make all install clean cleandepend KMODDIR=/boot/kernel Example 5: Quickly rebuild a kernel in place Quickly rebuild and reinstall the kernel, only recompiling the files changed since last build; note that this will only work if the full kernel build has been completed in the past, not on a fresh source tree: cd /usr/src make kernel KERNFAST=1 Example 6: Cross-compiling for different architectures To rebuild parts of FreeBSD for another CPU architecture, first prepare your source tree by building the cross-toolchain: cd src make toolchain TARGET_ARCH=aarch64 The following sequence of commands can be used to cross-build the sys- tem for the arm64 (aarch64) architecture on a different host architec- ture, such as amd64: cd /usr/src make TARGET_ARCH=aarch64 buildworld buildkernel make TARGET_ARCH=aarch64 DESTDIR=/armclient installworld installkernel Afterwards, to build and install a single piece of userspace, use: cd src/bin/ls make buildenv TARGET_ARCH=aarch64 make clean all install DESTDIR=/armclient Likewise, to quickly rebuild and reinstall the kernel, use: cd src make buildenv TARGET_ARCH=aarch64 make kernel KERNFAST=1 DESTDIR=/armclient DIAGNOSTICS Bad system call (core dumped) rescue/sh check failed, installation aborted The kernel was not updated due to incorrect build procedure. Study the examples above. SEE ALSO cc(1), install(1), make(1), make.conf(5), src.conf(5), arch(7), development(7), freebsd-base(7), pkg(7), ports(7), release(7), tests(7), config(8), etcupdate(8), nextboot(8), shutdown(8) HISTORY The build manpage first appeared in FreeBSD 4.3. AUTHORS Mike W. Meyer <mwm@mired.org> CAVEATS Old objects can cause obscure build problems; try `make cleandir cleandir'. Environment poisioning can cause obscure build problems; try prefixing make(1) commands with `env -i' When doing a major release upgrade, booting into single user mode for installworld is required. Updating the boot loader(8) is architecture specific. Consult boot(8) for your architecture for more details. FreeBSD 15.0 September 25, 2025 BUILD(7)
NAME | DESCRIPTION | ENVIRONMENT | FILES | EXAMPLES | DIAGNOSTICS | SEE ALSO | HISTORY | AUTHORS | CAVEATS
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