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[Embedded System] Deploy Linux v5.13 onto qemu vexpress-a9
Table of Contents
Beginners Guide
Given the fact the the tutorials are mostly focused on Linux v4, and you will find that it doesnt work out by simply follow these tutorials to deploy v5.13, this blog aims to cover the latest Linux version of the time (2021/10/29), v5.13.
If you are a total beginner to this, start here!
- Visit The Linux Kernel Archives
- Visit BUSYBOX v1.34.1
- See 奔跑吧-linux內核-qemu調試內核-软件开发平台及语言笔记大全(超详细)
- See QEMU搭建arm Linux開發環境
- See ubuntu-16.04 qemu 嵌入式arm模拟
- See qemu参数大全
- See 嵌入式 C語言自我修養 — 從芯片、編譯器到操作系統
- See /etc/inittab,/etc/init.d/rcS和/etc/profile分析
- install related library and tools
- Start
Install library and tools
sudo apt-get install qemu qemu-system-arm libncurses5-dev gcc-arm-linux-gnueabi build-essential flex bison
Linux v5.14.14 (stable)
Download it
wget https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.14.14.tar.xz
and untar it ztex
$> cd linux-5.14.14
linux-5.14.14> CROSS_COMPILE=arm-linux-gnueabi-
linux-5.14.14> ARCH=arm
linux-5.14.14> make CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm vexpress_defconfig
linux-5.14.14> make CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm dtbs
linux-5.14.14> make CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm
After this, you can get, dtb file (describe hardware configuration of vexpress-a9), zImage (kernel image)
BUSYBOX v1.34.1
$> wget https://busybox.net/downloads/busybox-1.34.1.tar.bz2
and untar it ztex
$> cd busybox-1.34.1
busybox-1.34.1> CROSS_COMPILE=arm-linux-gnueabi-
busybox-1.34.1> ARCH=arm
busybox-1.34.1> make CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm menuconfig
Settings —>
— Build Options
[ ] Build static binary (no shared libs)
Image Not Showing
Possible Reasons
- The image file may be corrupted
- The server hosting the image is unavailable
- The image path is incorrect
- The image format is not supported
Image Not Showing
Possible Reasons
- The image file may be corrupted
- The server hosting the image is unavailable
- The image path is incorrect
- The image format is not supported
busybox-1.34.1> CROSS_COMPILE=arm-linux-gnueabi-
busybox-1.34.1> ARCH=arm
busybox-1.34.1> make CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm
busybox-1.34.1> make CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm install
You will see there is a
_installdirectory, we are gonna use this to make our ramfs. ztex
busybox-1.34.1> mkdir rootfs
busybox-1.34.1> cp -r _install/* rootfs
busybox-1.34.1> mkdir rootfs/lib
busybox-1.34.1> mkdir rootfs/dev
busybox-1.34.1> cp -p /usr/arm-linux-gnueabi/lib/* rootfs/lib
(cuz we need arm library to execute on the arm platform)
busybox-1.34.1> sudo mknod -m 666 rootfs/dev/tty1 c 4 1
busybox-1.34.1> sudo mknod -m 666 rootfs/dev/tty2 c 4 2
busybox-1.34.1> sudo mknod -m 666 rootfs/dev/tty3 c 4 3
busybox-1.34.1> sudo mknod -m 666 rootfs/dev/tty4 c 4 4
(create serial devices)
busybox-1.34.1> sudo mknod -m 666 rootfs/dev/console c 5 1
(create console)
busybox-1.34.1> sudo mknod -m 666 rootfs/dev/null c 1 3
(create null)
Now, we have created the rootfs, let's make our image file. based on a ext4 file system format!ztex
➜ rootfs ls
bin dev etc lib linuxrc proc sbin sys usr
➜ rootfs file linuxrc
linuxrc: symbolic link to bin/busybox
note that this first thing been executed is
linuxrc, which is a symbolic link tobin/busyboxztex
busybox-1.34.1> dd if=/dev/zero of=a9rootfs.ext4 bs=1M count=64
busybox-1.34.1> mkfs.ext4 a9rootfs.ext4
busybox-1.34.1> mount -t ext4 a9rootfs.ext4 /mnt/ -o loop
busybox-1.34.1> cp -r rootfs/* /mnt
busybox-1.34.1> umount /mnt
while the other tutorials use 32M. I found that 32M gives no enough space, so I adjust it to 64Mztex
Mount proc sys fs
mkdir rootfs/proc
mkdir rootfs/sys
mkdir rootfs/etc
mkdir rootfs/etc/init.d
touch rootfs/etc/init.d/rcS
touch rootfs/etc/inittab
chmod -R 777 rootfs/etc
rootfs
├── bin
├── dev
├── etc
├── lib
├── linuxrc -> bin/busybox
├── proc
├── sbin
├── sys
└── usr
➜ busybox-1.34.1 tree rootfs/etc -L 2
rootfs/etc
├── init.d
│ └── rcS
└── inittab
inittab
#first:run the system script file
::sysinit:/etc/init.d/rcS
::askfirst:-/bin/sh
::ctrlaltdel:-/sbin/reboot
#umount all filesystem
::shutdown:/bin/umount -a -r
#restart init process
::restart:/sbin/init
init.d/rcS
#!/bin/sh
mount -t proc none /proc
mount -t sysfs none /sys
mount -o remount,rw /
/sbin/mdev -s
#/sbin/umount -a
#/sbin/mount -a
#/sbin/mount -t ext4 remount rw /
see [Linux筆記] 利用 mount 指令解決 Read-only file system 問題
see 用busybox制作文件系统
see 移植Linux操作系統時候遇到的問題
➜ busybox-1.34.1 cat mkrootfs.sh
mkdir rootfs
cd rootfs
mkdir -pv proc sys dev etc etc/init.d
touch etc/inittab
touch etc/init.d/rcS
chmod -R 777 etc
cd ..
cp -r _install/* rootfs
mknod -m 666 rootfs/dev/tty1 c 4 1
mknod -m 666 rootfs/dev/tty2 c 4 2
mknod -m 666 rootfs/dev/tty3 c 4 3
mknod -m 666 rootfs/dev/tty4 c 4 4
mknod -m 666 rootfs/dev/console c 5 1
mknod -m 666 rootfs/dev/null c 1 3
dd if=/dev/zero of=a9rootfs.ext4 bs=1M count=64
mkfs.ext4 a9rootfs.ext4
mount -t ext4 a9rootfs.ext4 /mnt/ -o loop
cp -r rootfs/* /mnt
umount /mnt
Fire QEMU
$> qemu-system-arm -M vexpress-a9 -m 512M -kernel arch/arm/boot/zImage -dtb arch/arm/boot/dts/vexpress-v2p-ca9.dtb -nographic -append "root=/dev/mmcblk0 console=ttyAMA0" -sd a9rootfs.ext4
What's next
Now we can develop and modify linux kernel and test&debug on qemu!!
Appendix and FAQ
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