### Qemu Arm Cortex-m4 mps2-an386 HOWTO

#### 1. Brief introduction
`arm_mps2_an386/` subdirectory contains part of the OpenHarmony LiteOS demonstration support for Qemu Arm Cortex-m4 mps2-an386 Platform,
here called *arm_mps2_an386*.
cortex-m4 Virtual platform is a `qemu-system-arm` machine target that provides emulation
for a generic, arm-based board.

Introduced functionality adds support for Cortex-m4 (1 CPU with security extensions), 16MB memory virtual platform.

Note: System memory size is hard-coded to 16MB.

#### 2. Setting up environment

[Setting up a development environment](https://gitee.com/openharmony/docs/blob/master/en/device-dev/quick-start/Readme-EN.md)

Compiler install

1.Command to install

Note: Command to install toolchain without arm-none-eabi-gdb, gdb cannot be debugged.

```
sudo apt install gcc-arm-none-eabi
```

2.The installation package to install

Note: If you have already passed the command to install gcc-arm-none-eabi, can through the command: `sudo apt remove
gcc-arm-none-eabi` after unloading, install again.

Download toolchain: [package](https://armkeil.blob.core.windows.net/developer/Files/downloads/gnu-rm/6-2017q2/gcc-arm-none-eabi-6-2017-q2-update-linux.tar.bz2)。

```
chmod 777 gcc-arm-none-eabi-6-2017-q2-update-linux.tar.bz2
tar -xvf gcc-arm-none-eabi-6-2017-q2-update-linux.tar.bz2 install_path
```

Add the installation path to the environment variable:

```
vim ~/.bashrc
```

Add the following command line to the last line of ~/.bashrc:

```
export PATH=$PATH:install_path/gcc-arm-none-eabi-6-2017-q2-update/bin
```

#### 3. Code acquisition

[Code acquisition](https://gitee.com/openharmony/docs/blob/HEAD/en/device-dev/get-code/sourcecode-acquire.md)

Note: One can use `repo` to fetch code in a straightforward manner.

#### 4. Building from sources

In the root directory of the obtained source code, run the following command:

```
hb set
```

Select `qemu_mini_system_demo` under **ohemu**.

Run the following build command:
```
hb build -f
```

This will build `OHOS_Image` for Qemu Cortex-m4 mps2-an386 machine.


After build is finished, the resulting image can be found in:
```
out/arm_mps2_an386/qemu_mini_system_demo/
```
#### 5. Running image in Qemu

a) If not installed, please install `qemu-system-arm`
For details, please refer to the HOWTO: [Qemu installation](https://gitee.com/openharmony/device_qemu/blob/HEAD/README.md)

b) Run

Run the `./qemu-run --help` command. The following information is displayed:

```
Usage: qemu-run [OPTION]...
Run a OHOS image in qemu according to the options.

    Options:

    -e, --exec file_name     kernel exec file name
    -n, --net-enable         enable net
    -g, --gdb                enable gdb for kernel
    -t, --test               test mode, exclusive with -g
    -h, --help               print help info

    By default, the kernel exec file is: out/arm_mps2_an386/qemu_mini_system_demo/OHOS_Image.
```

#### 6. gdb debug

```
cd device/qemu/arm_mps2_an386
vim liteos_m/config.gni
```

In the modified `board_opt_flags` compiler options:

```
board_opt_flags = []
```
to:

```
board_opt_flags = [ "-g" ]
```

Save and exit, recompile under OHOS root directory:

```
hb build -f
```

In a window to enter the command:

```
./qemu-run -g
```

In another window to enter the command:

```
arm-none-eabi-gdb out/arm_mps2_an386/qemu_mini_system_demo/OHOS_Image
(gdb) target remote localhost:1234
(gdb) b main
```

More GDB related debugging can refer to [GDB instruction manual](https://sourceware.org/gdb/current/onlinedocs/gdb).

# Qemu Arm Cortex-m4 mps2-an386 教程

## 1. 简介
`arm_mps2_an386/` 子目录包含部分Qemu arn cortex-m4虚拟化平台验证的OpenHarmony kernel\_liteos\_m的代码，目录名为*arm_mps2_an386*。
Arm Cortex-m4 虚拟化平台是一个 `qemu-system-arm` 的目标设备，通过它来模拟一个通用的、基于arm cortex-m4架构的单板。

这次模拟的配置是：arm cortex-m4架构，1个CPU，16M内存。

提示: 系统内存硬编码为16MB。

## 2. 环境搭建

[环境搭建](https://gitee.com/openharmony/docs/blob/master/zh-cn/device-dev/porting/Readme-CN.md)

编译器安装

1.命令安装

提示：命令安装的工具链无 arm-none-eabi-gdb，无法进行gdb调试

```
sudo apt install gcc-arm-none-eabi
```

2.安装包安装

提示：如果已经通过命令安装了gcc-arm-none-eabi， 可以通过命令：`sudo apt remove gcc-arm-none-eabi` 卸载之后，再进行安装。

下载工具链[安装包](https://armkeil.blob.core.windows.net/developer/Files/downloads/gnu-rm/6-2017q2/gcc-arm-none-eabi-6-2017-q2-update-linux.tar.bz2)。

```
chmod 777 gcc-arm-none-eabi-6-2017-q2-update-linux.tar.bz2
tar -xvf gcc-arm-none-eabi-6-2017-q2-update-linux.tar.bz2 install_path
```

将安装路径添加到环境变量中:

```
vim ~/.bashrc
```

在~/.bashrc最末尾加入:

```
export PATH=$PATH:install_path/gcc-arm-none-eabi-6-2017-q2-update/bin
```

## 3. 获取源码

[代码获取](https://gitee.com/openharmony/docs/blob/HEAD/zh-cn/device-dev/get-code/sourcecode-acquire.md)

提示: 可以使用 `repo` 命令来获取源码。

## 4. 源码构建

在已经获取的源码根目录，请输入：

```
hb set
```

选择ohemu下的`qemu_mini_system_demo`选项。


然后执行构建命令如下：
```
hb build -f
```

这个命令构建会产生 `OHOS_Image` 的镜像文件。

在构建完成之后，对应的镜像文件在如下目录：
```
out/arm_mps2_an386/qemu_mini_system_demo/
```
## 5. 在Qemu中运行镜像

a) 如果没有安装 `qemu-system-arm` ，安装请参考链接:[Qemu安装指导](https://gitee.com/openharmony/device_qemu/blob/HEAD/README_zh.md)

b) 运行

执行`./qemu-run --help`提示如下：

```
Usage: qemu-run [OPTION]...
Run a OHOS image in qemu according to the options.

    Options:

    -e, --exec file_name     kernel exec file name
    -n, --net-enable         enable net
    -g, --gdb                enable gdb for kernel
    -t, --test               test mode, exclusive with -g
    -h, --help               print help info

    By default, the kernel exec file is: out/arm_mps2_an386/qemu_mini_system_demo/OHOS_Image.
```

## 6. gdb调试

```
cd device/qemu/arm_mps2_an386
vim liteos_m/config.gni
```

将 `board_opt_flags` 中的

```
board_opt_flags = []
```

编译选项修改为:

```
board_opt_flags = [ "-g" ]
```

保存并退出，在OHOS根目录重新编译:

```
hb build -f
```

在一个窗口中输入命令：

```
./qemu-run -g
```

在另一个窗口中输入命令：

```
arm-none-eabi-gdb out/arm_mps2_an386/qemu_mini_system_demo/OHOS_Image
(gdb) target remote localhost:1234
(gdb) b main
```

更多gdb相关的调试可以查阅：[gdb指导手册](https://sourceware.org/gdb/current/onlinedocs/gdb)。