Ubuntu 根文件系统定制

以下基于 Ubuntu 18.04 64bit 根文件系统定制为例。

准备工作

安装 qemu

在 Linux PC 主机上安装模拟器：

   sudo apt-get install qemu-user-static

下载和解压 ubuntu-core

用户可以到

ubuntu cdimg

 下载，选择下载 "ubuntu-base-18.04.5-base-arm64.tar.gz"。

下载完之后，创建临时文件夹并解压根文件系统：

   mkdir temp
   sudo tar -xpf ubuntu-base-18.04.5-base-arm64.tar.gz -C temp

修改根文件系统

准备工作

准备网络：

   sudo cp -b /etc/resolv.conf temp/etc/resolv.conf

准备 qemu：

   sudo cp /usr/bin/qemu-aarch64-static temp/usr/bin/

创建一个挂载脚本，命名为 mount.sh，脚本内容如下：

   #!/bin/bash
   mnt() {
   	echo "MOUNTING"
   	sudo mount -t proc /proc ${2}proc
   	sudo mount -t sysfs /sys ${2}sys
   	sudo mount -o bind /dev ${2}dev
   	sudo mount -o bind /dev/pts ${2}dev/pts
   }
   umnt() {
   	echo "UNMOUNTING"
   	sudo umount ${2}proc
   	sudo umount ${2}sys
   	sudo umount ${2}dev/pts
   	sudo umount ${2}dev
   }

   if [ "$1" == "-m" ] && [ -n "$2" ] ;
   then
   	mnt $1 $2
   elif [ "$1" == "-u" ] && [ -n "$2" ];
   then
   	umnt $1 $2
   fi

添加执行权限并使用脚本进行挂载：

注意：稍后定制完成一定要记得取消挂载！！！

   chmod +x mount.sh
   ./mount.sh -m temp/

进入根文件系统进行操作：

   sudo chroot temp

更新及安装

更新：

   apt update
   apt upgrade

至少需要安装一个 systemd，否则开机无法进入系统

   apt install -y systemd

安装自己需要的功能

   apt install vim git ....(根据自己需求添加)

安装 xubuntu：

   apt-get install xubuntu-desktop

可能出现错误:

   E: Unable to locate package xxxx

安装包的源没有添加到 "/etc/apt/source.list" 中,导致无法识别安装包,可以
自行添加源，也可以使用下面给出的 "source.list" 覆盖原来的
"/etc/apt/source.list" 文件:

   # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
   # newer versions of the distribution.

   deb http://ports.ubuntu.com/ubuntu-ports/ bionic main restricted
   deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic main restricted

   ## Major bug fix updates produced after the final release of the
   ## distribution.
   deb http://ports.ubuntu.com/ubuntu-ports/ bionic-updates main restricted
   deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic-updates main restricted

   ## Uncomment the following two lines to add software from the 'universe'
   ## repository.
   ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
   ## team. Also, please note that software in universe WILL NOT receive any
   ## review or updates from the Ubuntu security team.
   deb http://ports.ubuntu.com/ubuntu-ports/ bionic universe
   deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic universe
   deb http://ports.ubuntu.com/ubuntu-ports/ bionic-updates universe
   deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic-updates universe

   ## N.B. software from this repository may not have been tested as
   ## extensively as that contained in the main release, although it includes
   ## newer versions of some applications which may provide useful features.
   ## Also, please note that software in backports WILL NOT receive any review
   ## or updates from the Ubuntu security team.
   deb http://ports.ubuntu.com/ubuntu-ports/ bionic-backports main restricted
   deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic-backports main restricted

   deb http://ports.ubuntu.com/ubuntu-ports/ bionic-security main restricted
   deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic-security main restricted
   deb http://ports.ubuntu.com/ubuntu-ports/ bionic-security universe
   deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic-security universe
   deb http://ports.ubuntu.com/ubuntu-ports/ bionic-security multiverse
   deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic-security multiverse

添加用户及设置密码

添加用户：

   useradd -s '/bin/bash' -m -G adm,sudo firefly

给用户设置密码：

   passwd firefly

给root用户设置密码：

   passwd root

修改完自己的根文件系统就可以退出了。

   exit

一定要取消挂载：

   ./mount.sh -u temp/

制作根文件系统

制作自己的根文件系统，大小依据自己的根文件系统而定，注意依据 "temp" 文
件夹的大小来修改 "count" 值：

   mkdir  rootfs
   dd if=/dev/zero of=linuxroot.img bs=1M count=4000
   mkfs.ext4 linuxroot.img
   sudo mount linuxroot.img rootfs/
   sudo cp -rfp temp/*  rootfs/
   sudo umount rootfs/
   e2fsck -p -f linuxroot.img
   resize2fs  -M linuxroot.img

这样 "linuxroot.img" 就是最终的根文件系统映像文件了。

FAQs

根文件系统加载后，大小不正常，未占满整个分区：

在系统正确加载后执行扩展文件系统命令：

   resize2fs /dev/mtd/by-name/linuxroot