Post on 22-Dec-2015
Building Embedded Linux System
2005/09/21 Reporter: sih-han wang
StrongARMStrongARM
32-bit StrongARM RISC processor 執行速度 :max 206 MHz
連結式規劃
Cross-platformDevelopmentEnvironment
Host•Bootloader•Kernel•Root Filesystem
Target
There are four main steps to creating a target Linux system
Determine system components
Configure and build the kernel
Build root filesystem
Set up boot software and configuration
Extract and decompress the Kernel Image and RAMDISK
Launch kernel
Initialize Memory and Hardware
Mount Root Filesystem (RAMDISK)
Run /sbin/init
User Programs
Bootloader
Kernel
Make Kernel 使用 Linux kernel
需要 Linux kernel source + some patches if needed
cross-compiler
Kernel Configuration make config
這種模式需要逐行輸入所需要設定的項目,無法往前修改設定,所以目前很少使用這種方式來設定 Kernel 的項目了
make xconfig 這種模式則是使用 X-Window 為主要環境的設定模式!
除非你有 X-Window 在執行,否則沒有辦法使用這種模式;
make menuconfig----Makefile 這種模式有點像是文字界面的選單模式,較為簡便,
而且可以在純文字界面下面執行編輯動作!
Kernel Compiling
make cleanmake menuconfig
( gzip –dc /home/ patch-2.4.18-rmk7.gz | patch –p1 –d arm-linux
gzip –dc /home/ diff-2.4.18-rmk7-pxa3.gz | patch –p1 –d arm-linux)
make assabet_config make oldconfig make dep make zImage
Additional Options:ARCH=arm CROSS_COMPILE=arm-linux-
Make Root Filesystem
Filesystem:
Busybox
Device node
Configuration
BusyBox Combine tiny versions of many common UNIX into a
single small executable. Provide a fairly complete environment for any smal
l or embedded system. BusyBox has been written with size-optimization a
nd limited resources in mind. It is also extremely modular so you can easily include or exclude commands (or features) at compile time. This makes it easy to customize your embedded systems
Ex: ls dd cp cat tar chmod mknod find ps
Make Busybox make menuconfig ln –s /home/arm-linux/include/linux/version.h vers
ion.h (/usr/local/arm/2.95.3/arm-linux/include/linux) make
make PREFIX=../busybox_arm install
Device Files 檔名 類型 主編號 次編號 權限 mknod console c 5 1 600
mknod tty0 c 5 0 600
mknod mem c 1 1 600
mknod null c 1 3 666
mknod random c 1 8 644
initrd initrd provides the capability to load a RAM disk by th
e boot loader. This RAM disk can then be mounted as the root file sys
tem and programs can be run from it. Afterwards, a new root file system can be mounted fro
m a different device. The previous root (from initrd) is then moved to a directory and can be subsequently unmounted.
initrd is mainly designed to allow system startup to occur in two phases, where the kernel comes up with a minimum set of compiled-in drivers, and where additional modules are loaded from initrd.
Make INITRD image dd if=/dev/zero of=/home/initrd.img bs=1k count=8192 su root mke2fs -F -v -m0 /home/initrd.img mkdir tmp mount -o loop initrd.img tmp/ cp ~/root-fs/* /home/tmp/ -dpRrf umount tmp/ gzip -9 < initrd.img > initrd.bin
8MB fileis null
~/root-fs
mount
Write DATA
8MB filewith data
unmount
Write Shell Script /etc/inittab
::sysinit:/etc/rc.S ::askfirst:/bin/sh
/etc/rc.S #!/bin/sh mount -t proc proc /proc
Cross-Compiler X86 Architecture code
ARM(Advanced RISC Machine) execution
-----------------------------
Cross-Compiler
在 /etc/bashrc 中加入PATH=$PATH:/usr/local/arm/2.95.3/bin
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