Creating a RFS with Buildroot

Info Box Applies to Linux Applies to Naon

Introduction

Buildroot is a set of scripts and patches for the creation of a cross-compilation toolchain as well as the creation of a complete root file system. Buildroot provides:

• support for prebuilt or external toolchains
• configuration through menuconfig, gconfig and xconfig interfaces
• lots of available libraries, tools, packages and utilities
• support for all the major filesystems (JFFS2, UBIFS, CRAMFS, ...)
• uClibc, glibc, eglibc generation, or use of the libc from the external toolchain
• easy customization through Makefiles

References

• Buildroot project page: http://buildroot.uclibc.org/

• Buildroot User Manual: http://buildroot.uclibc.org/downloads/manual/manual.html

• Buildroot on eLinux: http://elinux.org/Buildroot

Getting Buildroot

Buildroot releases can be downloaded from http://buildroot.net/downloads/

Daily Snapshots of the latest Buildroot source tree can be downloaded from http://buildroot.uclibc.org/downloads/snapshots/

The source tree can be browsed online: http://git.buildroot.net/buildroot/ and a copy of the repository can be grabbed with the following commands:

• git clone git://git.buildroot.net/buildroot
• git clone http://git.buildroot.net/git/buildroot.git (Use this if you're behind a firewall blocking git)

The following is the project directory tree:

.
├── arch
├── board
├── boot
├── CHANGES
├── Config.in
├── Config.in.legacy
├── configs
├── COPYING
├── docs
├── fs
├── linux
├── Makefile
├── Makefile.legacy
├── package
├── support
├── system
└── toolchain

Configuring Buildroot

For modifying the Buildroot configuration, enter the project directory and enter the following command:

make menuconfig

You can optionally use the O= parameter to set a specific build folder:

make O=<path_to_build_directory> menuconfig

Setting up the target architecture

From the menuconfig interface, you need to select:

• Target Architecture -> Select "ARM (little endian)"
• Target Architecture Variant -> Select "cortex-A8"
• Target ABI -> Select "EABI"

Setting up the external toolchain

You need to set the path and prefix for the external toolchain:

• Toolchain -> Toolchain type -> Select "External Toolchain"
• Toolchain -> Toolchain -> Select "Custom Toolchain"
• Toolchain -> Toolchain origin-> Select "Pre-installed toolchain"
• Toolchain -> Toolchain path (eg. /home/shared/devel/dave/naon-DAA/sw/linux/sdk/arm-2009q1)
• Toolchain -> Toolchain prefix (eg. $(ARCH)-none-linux-gnueabi-)

System configuration

Entering the "System configuration" option you should set:

• System hostname (NEW)
• System banner (NEW)
• Port to run a getty (login prompt) on -> Enter ttyO0
• () Custom script to run before creating filesystem images -> If required, you can run custom scripts to do board-specific cleanups, add-ons and the like, so the generated files can be used directly without further processing.

Package selection

The list of available packages can be accessed entering the Package selection for the target option