development - introduction to development with the FreeBSD codebase
Please note that what is being described here is based on a complete Fx environment, not just the Fx kernel. The methods described here are as applicable to production installations as it is to development environments. You need a good 12-17GB of disk space on one machine to make this work conveniently.
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 making it a separate partition for several reasons. First, as a safety measure 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 5GB.
On the master server, use cvsup(1)PqPaports/net/cvsup to automatically pull down and maintain the Fx CVS archive once a day. The first pull will take a long time, it is several gigabytes, but once you have it, the daily synchronizations 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 cvsup(1) configuration file example directly from /usr/share/examples without modification by supplying appropriate arguments to cvsup(1).
33 6 * * * /usr/local/bin/cvsup -g -r 20 -L 2 -h cvsup.freebsd.org /usr/share/examples/cvsup/cvs-supfile
Run the cvsup(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 cvsup(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) operation. 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 there.
# 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 environment. 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 automatically 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 Fx 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:
(ONLY IF YOU MADE A POOR CHOICE AND PUT /usr/obj in /FreeBSD!) 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 simply 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:
(THESE COMMANDS ON THE MASTER SERVER AND ON ALL CLIENTS) 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.conf5 file on the master server and on all your clients:
You should try to make the directory you use for the ports working directory 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 softlinks (since this is on /usr these are per-machine) to where the distfiles and working space really are.
/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_enable="YES" nfs_server_flags="-u -t -n 4"
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 running -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.
(ON EACH 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
cd /usr/src make buildkernel KERNCONF=KERNELNAME
WARNING! If you are familiar with the old config/cd/make method of building a -STABLE kernel, note that the config(8) method will put the build environment in /usr/src/sys/i386/compile/KERNELNAME instead of in /usr/obj
Building a -CURRENT kernel
cd /usr/src2 (on the master server) make buildkernel KERNCONF=KERNELNAME
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
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
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 (interchangeably) 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 another.
(ON THE CLIENT) (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.conf5 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.
Many developers choose to maintain a local branch of Fx 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 Fx tree is based on CVS, the former is convenient.
First, you need to modify your cvsup(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 cvsup(1).
The Fx 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, etc.
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 information on using CVS, see cvs(1).
WARNING! The cvsup(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, cvsup(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 lossage 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.
(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 Fx 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 generally want the source to not change out from under me when I am developing 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 repository synchronized via cron(8).
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