Embedded Linux From Scratch in 90 minutes

Goals
- Linux kernel configuring and compiling;
- Root file system creation;
- Busybox compiling and installation;
- Device file creation;
- System initialization scripts: virtual file system, networking;
- Setup of a simple HTTP interface to the system.

1. Download fast processor emulator using a portable dynamic translator.

wget http://download.savannah.gnu.org/releases/qemu/qemu-0.12.2.tar.gz
tar zxvf qemu-0.12.2.tar.gz
cd qemu-0.12.2.tar.gz

Then you configure QEMU and build it (usually no options are needed):

./configure

install zlib if you need (apt-get install zlib1g-dev)

make

Then type as root user:

make install

2. Getting the Kernel sources:

wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.25.4.tar.gz

Start with a minimalistic kernel configuration

make allnoconfig

Adding settings specific to the embedded system
install ncurses if you need (apt-get install libncurses5-dev)

make menuconfig

Compiling:

make

You will get
arch/x86/boot/bzImage


3. Getting Busybox source

wget http://www.busybox.net/downloads/busybox-1.15.3.tar.gz

Configuring BusyBox

make menuconfig

choosing to build a statically, natively compiled executable.

Compiling busybox

make

Pre-installing busybox (in the _install/ subdirectory):

make install

4. Creating a root filesystem
Creating an empty file with a 1000K size:
dd if=/dev/zero of=rootfs.img bs=1k count=1000

Formating this file for the ext2 filesystem:
mkfs.ext2 -i 1024 -F rootfs.img

5. Populating the root filesystem
logged as root:
Creating a mount point:
mkdir /mnt/tmproot

Mounting the root filesystem image:
mount -o loop rootfs.img /mnt/tmproot

Copying the busybox file structure into the mounted image:
rsync -a busybox/_install/ /mnt/tmproot/
(or cp -ax busybox/_install/ /mnt/tmproot/)
chown -R root:rooot /mnt/tmproot/

Flushing the changes into the mounted filesystem image:
sync

6. Booting the Virtual System
Using the QEMU emulator as a bootloader
qemu -m 32 -hda rootfs.img -kernel linux-2.6.25.4/arch/x86/boot/bzImage -append "root=/dev/hda" -redir tcp:5555::80

click "Applications -> Internet -> Terminal Server Client"then fill in the Computer with "127.0.0.1:5900",and select VNC in the protocol, if VNC grayed, install vncviewer

apt-get install vncviewer