xref: /freebsd-10.2-release/tools/tools/tinybsd/README

# $FreeBSD: releng/10.2/tools/tools/tinybsd/README 236707 2012-06-07 09:14:28Z bz $

- TinyBSD

You must read this to know how to build embedded systems with TinyBSD.

- TinyBSD files

TinyBSD's creation conf files are available under /usr/src/tools/tools/tinybsd/conf 
and the script are available under /usr/src/tools/tools/tinybsd/tinybsd.

The system has been entirely based on the ease of image customization from
PicoBSD, and the compilation script based on NanoBSD's.

# ls /usr/src/tools/tools/tinybsd/conf
bridge/   default/  firewall/ minimal/  vpn/      wireless/  wrap/

We have these six pre configured images to build. On each directory we have 3 
main files in there. Let's see what each of them are:

# ls /usr/src/tools/tools/tinybsd/conf/default
TINYBSD            etc/               tinybsd.basefiles

TINYBSD: Just like PicoBSD had its kernel previously compiled, we call ours
TINYBSD.

# more TINYBSD

machine         i386
cpu             I486_CPU
cpu             I586_CPU
cpu             I686_CPU
ident           TINYBSD

#To statically compile in device wiring instead of /boot/device.hints
#hints          "GENERIC.hints"         #Default places to look for devices.
...

As you can see, it's a kernel file identical to your system's, leaving only
the task of enabling or disabling options, according to your needs.

tinybsd.basefiles: Just like PicoBSD had its crunch.conf file to define which
files we'd want the new system to have, in this one we'll have all files to be
put into our embedded system, already having all available files for running
the system well. Put in or take out the files you need according to your
needs. Let's see it:

# more tinybsd.basefiles
# contents of ${WORKDIR}/boot
boot/boot0
boot/boot1
boot/boot2
boot/defaults/loader.conf
boot/device.hints
...
# contents of ${WORKDIR}/bin
bin/[:bin/test
bin/cat
bin/chflags
bin/chio
bin/chmod
...

And so on. In case you'd want to add the binary "setkey", sitting on
/usr/sbin, you'd only need to add the following line inside the /usr/sbin part
of the file, like this:

usr/sbin/pw
usr/sbin/pwd_mkdb
usr/sbin/setkey

tinybsd.ports: Here you can add the applications from the FreeBSD Ports Collection 
which you want TinyBSD ports system to install in your embedded system. You whould 
list one application per line, mentioning its category and name, like the examples:
www/mini_httpd
net-mgmt/rate 

etc/: This is the directory where you can put your custom /etc configuration.

# ls /usr/src/tools/tools/tinybsd/tinybsd
tinybsd

tinybsd: This is the script that builds the entire system. You'll hardly
need to modify it at all. The idea is for it to create a temporary work
directory for it to create the entire system tree. Once done, it'll copy all
files listed in tinybsd.basefiles to this tree, then it'll compile a new
kernel using the definitions in the TINYBSD file, and finally copy the library
dependencies the binaries will have. We'll then populate /etc on that
temporary tree and put in a few important default configurations inside on
/usr/src/tools/tools/tinybsd/conf/YOURCHOICE/etc/ like rc.conf, fstab and others.

Finally, we create an empty image, according to your media's specifications,
passed on to the script on the command line, and copy the entire temporary
work tree into the image mounted on /mnt.

- Running TinyBSD

Now that we know how it works, it's time for us to build our own image. Let's
do that step-by-step.

1) Choose what pre-configured image you want.

2) Edit the TINYBSD kernel file and add/remove all options you'll need.

3) Edit the tinybsd.basefiles file and add/remove all binaries you'll need on
your system.

4) Copy all your /etc configuration which you want to conf/YOURIMAGE/etc/.

5) Gather the right information on your destination media. To do that, plug in
the device on the system and fetch the information using diskinfo(8):

# diskinfo -v /dev/ad2
ad2
        512             # sectorsize
        20060135424     # mediasize in bytes (19G)
        39179952        # mediasize in sectors
        38869           # Cylinders according to firmware.
        16              # Heads according to firmware.
        63              # Sectors according to firmware.

To create my image, I'll need to know the media size in sectors, Heads
according to firmware and Sectors according to firmware. Optionally, you may
define the name of the generated image's file, but if you don't, it'll be
named tinybsd.bin. Now that we have gathered these informations through
diskinfo, all we need to do is run tinybsd. Remember that it has 3
parameters plus 1 optional, and if you don't pass on the required ones, the
script will warn you about it:

# /usr/src/tools/tools/tinybsd/tinybsd
Woops!
   Usage: tinybsd <mediasize in sectors> <heads according to firmware> 
   <sectors according to firmware> <conf> [<tinybsd image name>]

   Example: tinybsd 62592 4 32

	or

   /usr/src/tools/tools/tinybsd/tinybsd 62592 4 32 wireless

   Run diskinfo(8) -v against your CF device to get correct information
   about your disk.

Passing on the parameters correctly:

# /usr/src/tools/tools/tinybsd/tinybsd 39179952 16 63 wireless
Creating directory hierarchy...
./bin missing (created)
./boot missing (created)
./boot/defaults missing (created)
./boot/kernel missing (created)
./boot/modules missing (created)
./dev missing (created)
./etc missing (created)
...

In the end, we have the generated tinybsd.bin image. Now we have to copy it to
its final destination:

# dd if=/usr/src/tools/tools/tinybsd/tinybsd.bin of=/dev/ad2

Boot up your new embedded system and log on it. If you're ever going to modify
it, you must first remount the root slice as read-write, as it operates by
default on read-only mode, saving disk writes and preventing data-loss in case
of power failures. To mount it for read-write, use mount:

# mount -u -o rw /

Once you're done, return it to read-only mode:

# mount -u -o ro /

The first thing you need to do after logging for the first time, is to set a
root password. By default, it's created with no root password.

If you run df(1), you'll see the following partitions:

# df
Filesystem 1K-blocks  Used Avail Capacity  Mounted on
/dev/ad0a      29359 19446  7565    72%    /
devfs              1     1     0   100%    /dev
procfs             4     4     0   100%    /proc
/dev/md0        3694   114  3286     3%    /var
/dev/md1        19566    6 17996     0%    /tmp 

As you can see, /var and /tmp are mounted on /dev/md0 and /dev/md1
respectively, using memory disk devices. That's because both /var and /tmp are
write-intensive, and as our system works mostly on read-only mode, we'd suffer
with writing problems there, so the memory disk approach works fine. On the
other hand, whenever you reboot the system, those directories' contents
(including logs on /var/log) will be lost. If you need to keep the contents of
those directories, I suggest you to always upload them to another box.

The configuration line that fires up the system script to create /var as a
memory disk partition is "varmfs="YES"", inside
/etc/rc.conf. Besides mounting /var as a memory disk device, it also populates
its tree with the necessary subdirectories. Initially, /var is created on
memory using only 32MB of space, and that's usually enough. Although, if you
find it necessary to tweak that configuration, you may edit this line of
/etc/rc.conf:

varsize="32m"

Change 32m to whatever value you see fit (in MBytes). Take care of not using
your entire memory for /var.

- Ports and TinyBSD

You can also install ports on the new system via ports. For that, you'll need
to set the PREFIX environment variable to the image's destination path. Let's
assume you want to install apache on the newly-created image. For that, I'd do
this:

# mdconfig -a -t vnode -f /usr/src/tools/tools/tinybsd/tinybsd.bin -u 0

That uses mdconfig to enable the memory disk 0.

# mount /dev/md0a /mnt

Now we've mounted the image on the temporary directory /mnt. Let's then
install apache via ports:

# cd /usr/ports/www/apache13
# make install PREFIX=/mnt/usr/local
===>  Vulnerability check disabled
>> apache_1.3.31.tar.gz doesn't seem to exist in /usr/ports/distfiles/.
>> Attempting to fetch from http://www.apache.org/dist/httpd/.
...
      This port has installed the following startup scripts which may cause
      these network services to be started at boot time.
/mnt/usr/local/etc/rc.d/apache.sh
....

Once the install is finished, let's verify that apache has indeed been
properly installed under our /mnt directory:

# cd /mnt/usr/local/sbin
# ls -lga httpd
-rwxr-xr-x  1 root  wheel  252439 Jul 14 15:31 httpd

Our software has been successfully installed. You must notice that at the end
of the install, it shows the full path for the PREFIX variable we passed it.
The problem with that is that at boot-time, your system is going to look for
it under /mnt instead of /usr. So we need to edit apache's initialization
script under /usr/local/etc/rc.d (apache.sh) and remove all instances of
"/mnt" in it.

WARNING: A very important thing to care about are dependencies. Before
installing anything, check to see if it has any dependencies, and that you'll
have enough disk space on the destination system for both the application
you're installing and its dependencies.

- Script download

TinyBSD is still a project under heavy development, both the script itself and
its documentation. 

In case you'd like to try or use the BETA version of the script, feel free to
download it from the project's official site at http://code.google.com/p/tinybsd/.