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DEVELOPMENT(7)	   FreeBSD Miscellaneous Information Manual	DEVELOPMENT(7)

     development -- introduction to development	with the FreeBSD codebase

     This manual page describes	how an ordinary	system operator, UNIX adminis-
     trator, or	developer can, without any special permission, obtain, main-
     tain, and modify the FreeBSD codebase as well as how to maintain a	master
     build which can then be exported to other machines	in your	network.  This
     manual page is targeted to	system operators, programmers, and developers.

     Please note that what is being described here is based on a complete
     FreeBSD environment, not just the FreeBSD kernel.	The methods described
     here are as applicable to production installations	as it is to develop-
     ment environments.	 You need a good 12-17GB of disk space on one machine
     to	make this work conveniently.

     Your master server	should always run a stable, production version of the
     FreeBSD operating system.	This does not prevent you from doing -CURRENT
     builds or development.  The last thing you	want to	do is to run an	unsta-
     ble environment on	your master server which could lead to a situation
     where you lose the	environment and/or cannot recover from a mistake.

     Create a huge partition called /FreeBSD.  8-12GB is recommended.  This
     partition will contain nearly all the development environment, including
     the CVS tree, broken-out source, and possibly even	object files.  You are
     going to export this partition to your other machines via a READ-ONLY NFS
     export so do not mix it with other	more security-sensitive	partitions.

     You have to make a	choice in regards to /usr/obj.	You can	put /usr/obj
     in	/FreeBSD or you	can make /usr/obj its own partition.  I	recommend mak-
     ing it a separate partition for several reasons.  First, as a safety mea-
     sure since	this partition is written to a great deal.  Second, because
     you typically do not have to back it up.  Third, because it makes it far
     easier to mix and match the development environments which	are described
     later in this document.  I	recommend a /usr/obj partition of at least

     On	the master server, use csup(1) to automatically	pull down and maintain
     the FreeBSD CVS archive once a day.  The first pull will take a long
     time, it is several gigabytes, but	once you have it, the daily synchro-
     nizations will be quite small.

	 mkdir /FreeBSD/FreeBSD-CVS
	 rm -rf	/home/ncvs
	 ln -s /FreeBSD/FreeBSD-CVS /home/ncvs

     The cron(8) job should look something like	this (please randomize the
     time of day!).  Note that you can use the csup(1) configuration file
     example directly from /usr/share/examples without modification by supply-
     ing appropriate arguments to csup(1).

	 33 6 *	* *	 /usr/bin/csup -r 20 -L	2 -h /usr/share/examples/cvsup/cvs-supfile

     Run the csup(1) manually the first	time to	pull down the archive.	It
     could take	all day	depending on how fast your connection is!  You will
     run all csup(1) and cvs(1)	operations as ``root'' and you need to set up
     a ~/.cvsrc	(/root/.cvsrc) file, as	shown below, for proper	cvs(1) opera-
     tion.  Using ~/.cvsrc to specify cvs(1) defaults is an excellent way to
     ``file and	forget'', but you should never forget that you put them	in

	 # cvs -q
	 diff -u
	 update	-Pd
	 checkout -P

     Now use cvs(1) to check out a -STABLE source tree and a -CURRENT source
     tree, as well as ports and	docs, to create	your initial source environ-
     ment.  Keeping the	broken-out source and ports in /FreeBSD	allows you to
     export it to other	machines via read-only NFS.  This also means you only
     need to edit/maintain files in one	place and all your clients automati-
     cally pick	up the changes.

	 mkdir /FreeBSD/FreeBSD-4.x
	 mkdir /FreeBSD/FreeBSD-current

	 cd /FreeBSD/FreeBSD-4.x
	 cvs -d	/home/ncvs checkout -rRELENG_4 src

	 cd /FreeBSD/FreeBSD-current
	 cvs -d	/home/ncvs checkout src
	 cvs -d	/home/ncvs checkout ports
	 cvs -d	/home/ncvs checkout doc

     Now create	a softlink for /usr/src	and /usr/src2.	On the main server I
     always point /usr/src at -STABLE and /usr/src2 at -CURRENT.  On client
     machines I	usually	do not have a /usr/src2	and I make /usr/src point at
     whatever version of FreeBSD the client box	is intended to run.

	 cd /usr
	 rm -rf	src src2
	 ln -s /FreeBSD/FreeBSD-4.x/src	src	 (could	be -CURRENT on a client)
	 ln -s /FreeBSD/FreeBSD-current/src src2 (MASTER SERVER	ONLY)

     Now you have to make a choice for /usr/obj.  Well,	hopefully you made it
     already and chose the partition method.  If you chose poorly you probably
     intend to put it in /FreeBSD and, if so, this is what you want to do:

	 mkdir /FreeBSD/obj
	 cd /usr
	 rm -rf	obj
	 ln -s /FreeBSD/obj obj

     Alternatively you may chose simply	to leave /usr/obj in /usr.  If your
     /usr is large enough this will work, but I	do not recommend it for	safety
     reasons (/usr/obj is constantly being modified, /usr is not).

     Note that exporting /usr/obj via read-only	NFS to your other boxes	will
     allow you to build	on your	main server and	install	from your other	boxes.
     If	you also want to do builds on some or all of the clients you can sim-
     ply have /usr/obj be a local directory on those clients.  You should
     never export /usr/obj read-write, it will lead to all sorts of problems
     and issues	down the line and presents a security problem as well.	It is
     far easier	to do builds on	the master server and then only	do installs on
     the clients.

     I usually maintain	my ports tree via CVS.	It is sitting right there in
     the master	CVS archive and	I have even told you to	check it out (see
     above).  With some	fancy softlinks	you can	make the ports tree available
     both on your master server	and on all of your other machines.  Note that
     the ports tree exists only	on the HEAD CVS	branch,	so its always -CURRENT
     even on a -STABLE box.  This is what you do:

	 cd /usr
	 rm -rf	ports
	 ln -s /FreeBSD/FreeBSD-current/ports ports

	 cd /usr/ports				 (this pushes into the softlink)
	 rm -rf	distfiles			 (ON MASTER SERVER ONLY)
	 ln -s /usr/ports.distfiles distfiles	 (ON MASTER SERVER ONLY)

	 mkdir /usr/ports.distfiles
	 mkdir /usr/ports.workdir

     Since /usr/ports is softlinked into what will be read-only	on all of your
     clients, you have to tell the ports system	to use a different working
     directory to hold ports builds.  You want to add a	line to	your
     make.conf(5) file on the master server and	on all your clients:


     You should	try to make the	directory you use for the ports	working	direc-
     tory as well as the directory used	to hold	distfiles consistent across
     all of your machines.  If there is	not enough room	in
     /usr/ports.distfiles and /usr/ports.workdir I usually make	those soft-
     links (since this is on /usr these	are per-machine) to where the dist-
     files and working space really are.

     The master	server needs to	export /FreeBSD	and /usr/obj via NFS so	all
     the rest of your machines can get at them.	 I strongly recommend using a
     read-only export for both security	and safety.  The environment I am
     describing	in this	manual page is designed	primarily around read-only NFS
     exports.  Your exports file on the	master server should contain the fol-
     lowing lines:

	 /FreeBSD -ro -alldirs -maproot=root: -network YOURLAN -mask YOURLANMASK
	 /usr/obj -ro -alldirs -maproot=root: -network YOURLAN -mask YOURLANMASK

     Of	course,	NFS server operations must also	be configured on that machine.
     This is typically done via	your /etc/rc.conf:

	 nfs_server_flags="-u -t -n 4"

     All of your client	machines can import the	development/build environment
     directory simply by NFS mounting /FreeBSD and /usr/obj from the master
     server.  A	typical	/etc/fstab entry on your client	machines will be some-
     thing like	this:

	 masterserver:/FreeBSD	   /FreeBSD	   nfs	   ro,bg    0	    0
	 masterserver:/usr/obj	   /usr/obj	   nfs	   ro,bg    0	    0

     And, of course, you should	configure the client for NFS client operations
     via /etc/rc.conf.	In particular, this will turn on nfsiod(8) which will
     improve client-side NFS performance:


     Each client should	create softlinks for /usr/ports	and /usr/src that
     point into	the NFS-mounted	environment.  If a particular client is	run-
     ning -CURRENT, /usr/src should be a softlink to
     /FreeBSD/FreeBSD-current/src.  If it is running -STABLE, /usr/src should
     be	a softlink to /FreeBSD/FreeBSD-4.x/src.	 I do not usually create a
     /usr/src2 softlink	on clients, that is used as a convenient shortcut when
     working on	the source code	on the master server only and could create
     massive confusion (of the human variety) on a client.

	 cd /usr
	 rm -rf	ports src
	 ln -s /FreeBSD/FreeBSD-current/ports ports
	 ln -s /FreeBSD/FreeBSD-XXX/src	src

     Do	not forget to create the working directories so	you can	build ports,
     as	previously described.  If these	are not	good locations,	make them
     softlinks to the correct location.	 Remember that /usr/ports/distfiles is
     exported by the master server and is therefore going to point to the same
     place (typically /usr/ports.distfiles) on every machine.

	 mkdir /usr/ports.distfiles
	 mkdir /usr/ports.workdir

     Here is how you build a -STABLE kernel (on	your main development box).
     If	you want to create a custom kernel, copy GENERIC to KERNELNAME and
     then edit it before configuring and building.  The	kernel configuration
     file lives	in /usr/src/sys/i386/conf/KERNELNAME.

	 cd /usr/src
	 make buildkernel KERNCONF=KERNELNAME

     WARNING! If you are familiar with the old config/cd/make method of	build-
     ing a -STABLE kernel, note	that the config(8) method will put the build
     environment in /usr/src/sys/i386/compile/KERNELNAME instead of in

     Building a	-CURRENT kernel

	 cd /usr/src2		 (on the master	server)
	 make buildkernel KERNCONF=KERNELNAME

     Installing	a -STABLE kernel (typically done on a client, only do this on
     your main development server if you want to install a new kernel for your
     main development server):

	 cd /usr/src
	 make installkernel KERNCONF=KERNELNAME

     If	you are	using the older	config/cd/make build mechanism for -STABLE,
     you would install using:

	 cd /usr/src/sys/i386/compile/KERNELNAME
	 make install

     Installing	a -CURRENT kernel (typically done only on a client)

	 (remember /usr/src is pointing	to the client's	specific environment)
	 cd /usr/src
	 make installkernel KERNCONF=KERNELNAME

     This environment is designed such that you	do all builds on the master
     server, and then install from each	client.	 You can do builds on a	client
     only if /usr/obj is local to that client.	Building the world is easy:

	 cd /usr/src
	 make buildworld

     If	you are	on the master server you are running in	a -STABLE environment,
     but that does not prevent you from	building the -CURRENT world.  Just
     cd(1) into	the appropriate	source directory and you are set.  Do not
     accidentally install it on	your master server though!

	 cd /usr/src2
	 make buildworld

     You can build on your main	development server and install on clients.
     The main development server must export /FreeBSD and /usr/obj via read-
     only NFS to the clients.

     NOTE!!! If	/usr/obj is a softlink on the master server, it	must also be
     the EXACT SAME softlink on	each client.  If /usr/obj is a directory in
     /usr or a mount point on the master server, then it must be (interchange-
     ably) a directory in /usr or a mount point	on each	client.	 This is
     because the absolute paths	are expected to	be the same when building the
     world as when installing it, and you generally build it on	your main
     development box and install it from a client.  If you do not set up
     /usr/obj properly you will	not be able to build on	machine	and install on

	 (remember /usr/src is pointing	to the client's	specific environment)
	 cd /usr/src
	 make installworld

     WARNING! If builds	work on	the master server but installs do not work
     from the clients, for example you try to install and the client complains
     that the install tried to write into the read-only	/usr/obj, then it is
     likely that the make.conf(5) file on the client does not match the	one on
     the master	server closely enough and the install is trying	to install
     something that was	not built.

     Developers	often want to run buildkernel's	or buildworld's	on client
     boxes simply to life-test the box.	 You do	this in	the same manner	that
     you buildkernel and buildworld on your master server.  All	you have to do
     is	make sure that /usr/obj	is pointing to local storage.  If you followed
     my	advise and made	/usr/obj its own partition on the master server, then
     it	is typically going to be an NFS	mount on the client.  Simply unmount-
     ing /usr/obj will leave you with a	/usr/obj that is a subdirectory	in
     /usr which	is typically local to the client.  You can then	do builds to
     your heart's content!

     I have described how to maintain two versions of the source tree, a sta-
     ble version in /FreeBSD/FreeBSD-4.x and a current version in
     /FreeBSD/FreeBSD-current.	There is absolutely nothing preventing you
     from breaking out other versions of the source tree into /FreeBSD/XXX.
     In	fact, my /FreeBSD partition also contains OpenBSD, NetBSD, and various
     flavors of	Linux.	You may	not necessarily	be able	to build non-FreeBSD
     operating systems on your master server, but being	able to	collect	and
     manage source distributions from a	central	server is a very useful	thing
     to	be able	to do and you can certainly export to machines which can build
     those other operating systems.

     Many developers choose to maintain	a local	branch of FreeBSD to test
     patches or	build a	custom distribution.  This can be done with CVS	or
     another source code management system (SubVersion,	Perforce, BitKeeper)
     with its own repository.  Since the main FreeBSD tree is based on CVS,
     the former	is convenient.

     First, you	need to	modify your csup(1) environment	to avoid it modifying
     the local changes you have	committed to the repository.  It is important
     to	remove the delete keyword from your supfile and	to add the CVSROOT
     subdirectory to your refuse file.	For more information, see csup(1).

     The FreeBSD version of cvs(1) examines a custom environmental variable,
     CVS_LOCAL_BRANCH_NUM, which specifies an integer to use when doing	a
     cvs(1) tag/rtag.  Set this	number to something high (say 1000) to avoid
     colliding with potential future branches of the main repository.  For
     example, branching	a file with version 1.4	produces 1.4.1000.  Future
     commits to	this branch will produce revisions 1.4.1000.1, 1.4.1000.2,

     To	fork your local	branch,	do:

	 cvs rtag -r RELENG_4 -b LOCAL_RELENG_4	src

     After this, you can check out a copy from your local repository using the
     new tag and begin making changes and committing them.  For	more informa-
     tion on using CVS,	see cvs(1).

     WARNING! The csup(1) utility may blow away	changes	made on	a local	branch
     in	some situations.  This has been	reported to occur when the master CVS
     repository	is directly manipulated	or an RCS file is changed.  At this
     point, csup(1) notices that the client and	server have entirely different
     RCS files,	so it does a full replace instead of trying to send just
     deltas.  Ideally this situation should never arise, but in	the real world
     it	happens	all the	time.

     While this	is the only scenario where the problem should crop up, there
     have been some suspicious-sounding	reports	of CVS_LOCAL_BRANCH_NUM	los-
     sage that cannot be explained by this alone.  Bottom line is, if you
     value your	local branch then you should back it up	before every update.

     The advantage of using csup(1) to maintain	an updated copy	of the CVS
     repository	instead	of using it to maintain	source trees directly is that
     you can then pick and choose when you bring your source tree (or pieces
     of	your source tree) up to	date.  By using	a cron(8) job to maintain an
     updated CVS repository, you can update your source	tree at	any time with-
     out any network cost as follows:

	 (on the main development server)
	 cd /usr/src
	 cvs -d	/home/ncvs update
	 cd /usr/src2
	 cvs -d	/home/ncvs update
	 cd /usr/ports
	 cvs -d	/home/ncvs update

     It	is that	simple,	and since you are exporting the	whole lot to your
     clients, your clients have	immediate visibility into the updated source.
     This is a good time to also remind	you that most of the cvs(1) operations
     you do will be done as ``root'', and that certain options are required
     for CVS to	operate	properly on the	FreeBSD	repository.  For example, -Pd
     is	necessary when running cvs update.  These options are typically	placed
     in	your ~/.cvsrc (as already described) so	you do not have	to re-specify
     them every	time you run a cvs(1) command.	Maintaining the	CVS repository
     also gives	you far	more flexibility in regards to breaking	out multiple
     versions of the source tree.  It is a good	idea to	give your /FreeBSD
     partition a lot of	space (I recommend 8-12GB) precisely for that reason.
     If	you can	make it	15GB I would do	it.

     I generally do not	cvs update via a cron(8) job.  This is because I gen-
     erally want the source to not change out from under me when I am develop-
     ing code.	Instead	I manually update the source every so often... when I
     feel it is	a good time.  My recommendation	is to only keep	the CVS	repos-
     itory synchronized	via cron(8).

     crontab(1), crontab(5), make.conf(5), build(7), firewall(7), release(7),
     tuning(7),	diskless(8)

     The development manual page was originally	written	by Matthew Dillon
     <> and first appeared in	FreeBSD	5.0, December 2002.

FreeBSD	11.1			 May 02, 2012			  FreeBSD 11.1


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