qemu arm 开发环境搭建

柔情只为你懂 2022-02-09 12:55 275阅读 0赞

# qemu arm 开发环境搭建 #

作者：吴甜甜 个人博客网站： wutiantian.github.io

`qemu` `arm`

--------------------

实验环境 ubuntu 18.04 qemu 4.0.0

## 1. 在 qemu 上模拟运行 linux 内核 ##

### 非图形化启动 ###

qemu-system-arm -M \
       vexpress-a9 -m 512M \
       -dtb linux-4.20.17/arch/arm/boot/dts/vexpress-v2p-ca9.dtb \
       -kernel linux-4.20.17/arch/arm/boot/zImage \
       -nographic \
       -append "console=ttyAMA0"

### 图形化启动 ###

*  4.0.0 版本直接启动会出现图形界面没有显示的情况，原因是 SDL 库的版本不够新，4.0.0 版本需要安装 libsdl2-dev - Simple DirectMedia Layer development files 版本，1.2 版本已经不能用了，导致 qemu 配置时 SDL 支持为 no ，安装 2 版本后，再进行配置就会发现 SDL 支持为 yes，重新安装即可。
 *  参考帖子 \[在Ubuntu下安装QEMU完毕后去测试arm，结果只输出一行VNC\]\[1\]

qemu-system-arm -M \
       vexpress-a9 -m 512M \
       -dtb linux-4.20.17/arch/arm/boot/dts/vexpress-v2p-ca9.dtb \
       -kernel linux-4.20.17/arch/arm/boot/zImage \
       -append "root=/dev/mmcblk0 rw console=tty0" \
       -sd rootfs.ext3

## 2. 制作根文件系统 ##

mkdir rootfs  
mkdir rootfs/lib  
cp –r \_install/\* rootfs  
cp -p /usr/arm-linux-gnueabi/lib/\* rootfs/lib  
mkdir -p rootfs/dev/  
mknod –m 666 tty1 c 4 1  
mknod –m 666 tty2 c 4 2  
mknod –m 666 tty3 c 4 3  
mknod –m 666 tty4 c 4 4  
mknod –m 666 console c 5 1  
mknod –m 666 null c 1 3

### 添加开机启动文件 rcS ###

echo '------------------------------------'  
echo 'Hello SummerGift!'  
echo '------------------------------------'

## 3. u-boot 配置编译与启动配置 ##

### 3.1 重新编译内核为 uImage，修改装载地址 ###

make LOADADDR=0x60003000 uImage -j4

### 3.2 修改启动命令，并重新编译 uboot ###

#undef CONFIG_BOOTCOMMAND
       
       #define CONFIG_BOOTCOMMAND \
       "tftp 0x60003000 uImage;tftp 0x60500000 vexpress-v2p-ca9.dtb; \
       setenv bootargs 'root=/dev/mmcblk0 console=ttyAMA0'; \
       bootm 0x60003000 - 0x60500000; "
       
       #define CONFIG_IPADDR 192.168.1.66
       #define CONFIG_NETMASK 255.255.255.0
       #define CONFIG_SERVERIP 192.168.1.198

### 3.3 启动 uboot 运行 ###

qemu-system-arm -M vexpress-a9 \
       -kernel u-boot \
       -nographic \
       -m 512M

### 3.4 uboot 通过 tftp 下载内核后启动脚本 ###

*  实际测试 4.0.0 版本会报错 vlan 参数无效，实际修改为下面的启动参数即可

-net nic \
       -net tap,ifname=tap0 \

*  全部启动参数

cp /home/summergift/linux_arm/linux-4.20.17/arch/arm/boot/uImage /home/summergift/linux_arm/tftpboot
       cp /home/summergift/linux_arm/linux-4.20.17/arch/arm/boot/dts/vexpress-v2p-ca9.dtb /home/summergift/linux_arm/tftpboot
       cp /home/summergift/linux_arm/rootfs.ext3 /home/summergift/linux_arm/tftpboot
       
       qemu-system-arm \
       -M vexpress-a9 \
       -kernel u-boot-2019.04/u-boot \
       -m 512M \
       -nographic \
       -net nic \
       -net tap,ifname=tap0 \
       -sd rootfs.ext3

如果想要图形化启动则去掉 -nographic 参数，并且修改启动命令中的 ttyAMA0 为 tty0。

## 4. 使用 nfs 挂载根文件系统 ##

### 4.1 修改 uboot 启动参数并重新编译 ###

### 4.2 开启内核 nfs 功能并重新编译 ###

VFS: Unable to mount root fs via NFS, trying floppy.  
VFS: Cannot open root device "nfs" or unknown-block(2,0): error -6  
Please append a correct "root=" boot option; here are the available partitions:  
1f00 131072 mtdblock0  
(driver?)  
1f01 32768 mtdblock1  
(driver?)  
b300 32768 mmcblk0  
driver: mmcblk  
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)  
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.20.17 \#3  
Hardware name: ARM-Versatile Express  
\[<80110914>\] (unwind\_backtrace) from \[<8010c80c>\] (show\_stack+0x10/0x14)  
\[<8010c80c>\] (show\_stack) from \[<80705078>\] (dump\_stack+0x88/0x9c)  
\[<80705078>\] (dump\_stack) from \[<801207ac>\] (panic+0x110/0x27c)  
\[<801207ac>\] (panic) from \[<80a01598>\] (mount\_block\_root+0x1ec/0x2d8)  
\[<80a01598>\] (mount\_block\_root) from \[<80a017c8>\] (mount\_root+0x144/0x160)  
\[<80a017c8>\] (mount\_root) from \[<80a01934>\] (prepare\_namespace+0x150/0x198)  
\[<80a01934>\] (prepare\_namespace) from \[<80a01180>\] (kernel\_init\_freeable+0x340/0x354)  
\[<80a01180>\] (kernel\_init\_freeable) from \[<8071bbb0>\] (kernel\_init+0x8/0x114)  
\[<8071bbb0>\] (kernel\_init) from \[<801010e8>\] (ret\_from\_fork+0x14/0x2c)  
Exception stack(0x9f48ffb0 to 0x9f48fff8)  
ffa0: 00000000 00000000 00000000 00000000  
ffc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000  
ffe0: 00000000 00000000 00000000 00000000 00000013 00000000  
\---\[ end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0) \]---

### 4.3 从网上搜索的解决办法 ###

在 nfsroot 配置项后面加上 proto=tcp,nfsvers=3,nolock 即可

#undef CONFIG_BOOTCOMMAND
       
       #define CONFIG_BOOTCOMMAND \
       "tftp 0x60003000 uImage;tftp 0x60500000 vexpress-v2p-ca9.dtb; \
       setenv bootargs 'root=/dev/nfs rw \
       nfsroot=192.168.1.198:/home/summergift/linux_arm/rootfs,proto=tcp,nfsvers=3,nolock init=/linuxrc \
       ip=192.168.1.66 console=tty0'; \
       bootm 0x60003000 - 0x60500000; "
       
       #define CONFIG_IPADDR 192.168.1.66
       #define CONFIG_NETMASK 255.255.255.0
       #define CONFIG_SERVERIP 192.168.1.198

### 4.4 图形化启动 uboot + kernel + rootfs + nfs ###

*  uboot 启动参数

*  qemu 启动参数项

make -C /home/summergift/linux_arm/linux-4.20.17 LOADADDR=0x60003000 uImage -j4
       cp /home/summergift/linux_arm/linux-4.20.17/arch/arm/boot/uImage /home/summergift/linux_arm/tftpboot
       cp /home/summergift/linux_arm/linux-4.20.17/arch/arm/boot/dts/vexpress-v2p-ca9.dtb /home/summergift/linux_arm/tftpboot
       cp /home/summergift/linux_arm/rootfs.ext3 /home/summergift/linux_arm/tftpboot
       
       qemu-system-arm \
       -M vexpress-a9 \
       -kernel u-boot-2019.04/u-boot \
       -m 512M \
       -net nic \
       -net tap,ifname=tap0 \
       -sd rootfs.ext3

### linux 启动顺序 ###

init->linuxrc->inittab->fstab->console

各种文件系统挂载之后就可以通过 cat 命令来查看系统信息了。