The creation of the Linux root file system

One. Creating root file system directories and files

1. Create a Directory

#mkdir Rootfs

#cd Rootfs

#mkdir bin Dev etc lib proc sbin sys usr MNT tmp var

#mkdir usr/bin usr/lib Usr/sbin lib/modules

2. Create a Device file

#cd Rootfs/dev

#mknod-M 666 console C 5 1

#mknod-M 666 null C 1 3

3. Join the configuration file

#tar etc.tar.gz

#mv etc/*/root/etc/-RF

4. Adding kernel modules

#cd .../linux

#make Modules Arch=arm cross_compile=arm-linux-

#make Modules_install Arch=arm Install_mod_path=.../rootfs

5. Compiling BusyBox

1. Configure BusyBox

#make Menuconfig

Busybox Settingsàbuild options->

* check "Build busybox as a static binary", Static link

*cross Compiler prefix (arm-linux-)

Installation options->

* Select "Don t use/usr" to prevent BusyBox from being installed in the/USR directory of the host system, destroying the host system

*busybox installation Prefix (/XXX/ROOTFS)

This option indicates the installation location of the compiled BusyBox

2. Compiling and installing BusyBox

#make

#make Install

Two. Mount the root file system to the kernel

1. Introduction to Mount Mode

(1). File system type

Depending on the hardware characteristics and system requirements of the storage device, different file system types have different application situations.

In embedded Linux applications, the main storage devices are RAM and flash,

Common storage device-based file system types include: JFFS2, YAFFS2, ubifs, RAMDisk, etc.

(2). System type

#基于nandflash的文件系统 YAFFS2, UbiFS (Readable and writable)

#基于norflash的文件系统 JFFS2

#基于内存的文件系统 Rmdisk, Initramfs

#基于网络的文件系统 NFS

2. Initranfs Mount

1. #cd/rootfs/#ln –s./bin/busybox Init

2. Configure the Linux kernel to support Initramfs

　　　　　　

3. Compiling

4. Setting Environment variables

Setenv BOOTARGSNOINITRD console=ttysac0,115200

3. NFS Mount

　　　　

Setenv Bootargs NOINITRD

console=ttysac0,115200 Init=/init

Root=/dev/nfs RW

nfsroot=192.168.1.3:/home/s5-arm/part4/rootfs,proto=tcp,nfsvers=

3ip=192.168.1.6:192.168.1.3:192.168.1.1:255.255.255.0::eth0:off

The creation of the Linux root file system