Интерактивная система просмотра системных руководств (man-ов)
nanobsd (8)
>> nanobsd (8) ( FreeBSD man: Команды системного администрирования )
BSD mandoc
NAME
nanobsd.sh
- utility used to create a FreeBSD system image suitable for embedded
applications
SYNOPSIS
[-bhkw
]
[-c config-file
]
DESCRIPTION
The
utility is a script which produces a minimal implementation of
Fx (called
NanoBSD )
which typically fits on a small media such as a Compact Flash card,
or other mass storage medium.
It can be used to build specialized install images, designed for easy
installation and maintenance.
The following options are available:
-b
Skip the build stages (both for kernel and world).
-c config-file
Specify the configuration file to use.
-h
Display usage information.
-k
Skip the
buildkernel
stage of the build.
-w
Skip the
buildworld
stage of the build.
The features of
NanoBSD
include:
Ports and packages work as in
Fx .
Every single application can be installed and used in a
NanoBSD
image, the same way as in
Fx .
No missing functionality.
If it is possible to do something with
Fx ,
it is possible to do the same thing with
NanoBSD
unless the specific feature or features were explicitly removed from the
NanoBSD
image when it was created.
Everything is read-only at run-time.
It is safe to pull the power-plug.
There is no necessity to run
fsck(8)
after a non-graceful shutdown of the system.
Easy to build and customize.
Making use of just one shell script and one configuration file it is
possible to build reduced and customized images satisfying any arbitrary
set of requirements.
NanoBSD
Media Layout
The mass storage medium is divided into three parts by default (which
are normally mounted read-only):
Two image partitions:
code#1
and
code#2
The configuration file partition, which can be mounted under the
/cfg
directory at run time.
The
/etc
and
/var
directories are
md(4)
(malloc backed) disks.
The configuration file partition persists under the
/cfg
directory.
It contains files for
/etc
directory and is briefly mounted read-only right after the system boot,
therefore it is required to copy modified files from
/etc
back to the
/cfg
directory if changes are expected to persist after the system restarts.
BUILDING NanoBSD
A
NanoBSD
image is built using a simple
shell script, which can be
found in the
src/tools/tools/nanobsd
directory.
This script creates a bootable image, which can be copied on the storage
medium using the
dd(1)
utility.
The necessary commands to build and install a
NanoBSD
image are:
cd /usr/src/tools/tools/nanobsd
sh nanobsd.sh
cd /usr/obj/nanobsd.full
dd if=_.disk.full of=/dev/da0 bs=64k
CUSTOMIZING NanoBSD
This is probably the most important and most interesting feature of
NanoBSD
This is also where you will be spending most of the time when developing with
NanoBSD
Customization is done in two ways:
Configuration options.
Custom functions.
With configuration settings, it is possible to configure options passed
to both the
buildworld
and
installworld
stages of the
NanoBSD
build process, as well as internal options passed to the main build
process of
NanoBSD
Through these options it is possible to cut the system down, so it will
fit on as little as 64MB.
You can use the configuration options to trim down the system
even more, until it will consist of just the kernel and two or three
files in the userland.
The configuration file consists of configuration options, which override
the default values.
The most important directives are:
NANO_NAME
Build name (used to construct the working directory names).
NANO_SRC
Path to the source tree used to build the image.
NANO_KERNEL
Name of the kernel configuration file used to build the kernel.
NANO_BOOT0CFG
Controls the options passed to
boot0cfg(8);
these dictate
boot0 's
behaviour.
NANO_BOOTLOADER
The
boot0
loader to use relative to the
NANO_WORLDDIR
variable.
This defaults to
boot/boot0sio
and should be overridden to
boot/boot0
to provide a VGA
console.
CONF_BUILD
Options passed to the
buildworld
stage of the build.
CONF_INSTALL
Options passed to the
installworld
stage of the build.
CONF_WORLD
Options passed to both the
buildworld
and
installworld
stages of the build.
FlashDevice
Defines the type of media to use.
Check the
FlashDevice.sub
file for more details.
For more configuration options, please check the
script.
To build
NanoBSD
image using the
nanobsd.conf
configuration file, use the following command:
sh nanobsd.sh -c nanobsd.conf
It is possible to fine-tune
NanoBSD
using shell functions in the configuration file.
The following example illustrates the basic model of custom functions:
