1# Getting Started of QEMU (Ubuntu) 2 3The development of embedded software is inseparable from the development board. Without physical development boards, similar virtual machines like QEMU can be used to simulate the development board. QEMU is a virtual machine that supports cross-platform virtualization. It can virtualize many development boards. To facilitate the experience of RT-Thread without a development board, RT-Thread provides a board-level support package (BSP) for QEMU-simulated **ARM vexpress A9** development board. 4 5## 1 Install dependency libraries 6 7We need to type commands as following in the terminal: 8 9```shell 10sudo apt install gcc 11sudo apt install python3 12sudo apt install python3-pip 13sudo apt install gcc-arm-none-eabi 14sudo apt install gdb-arm-none-eabi 15sudo apt install binutils-arm-none-eabi 16sudo apt install scons 17sudo apt install libncurses5-dev 18sudo apt install qemu 19sudo apt install qemu-system-arm 20sudo apt install git 21``` 22 23## 2 Get RT-Thread source code 24 25Download RT-Thread Source Code : `git clone https://github.com/RT-Thread/rt-thread.git` 26 27You can directly ignore the following steps, this is used for setting GCC compiler manually. Usually, you don't need to set this. 28 29> - Install the compiler. If the compiler version installed with `apt-get` command is too old, it will cause compilation errors. You can download and install the new version using the following command in turn. The download link and the decompression folder name will vary according to the download version. The following Compression Packet will unzip to the `/opt` folder. 30> 31> - `wget https://armkeil.blob.core.windows.net/developer/Files/downloads/gnu-rm/6-2016q4/gcc-arm-none-eabi-6_2-2016q4-20161216-linux.tar.bz2` 32> - `cd /opt` 33> - `sudo tar xf ~/gcc-arm-none-eabi-6_2-2016q4-20161216-linux.tar.bz2` 34> 35> 36> - After the compiler is installed, it is necessary to modify the `rtconfig.py` file under `rt-thread/bsp/qemu-vexpress-a9` BSP, modify the corresponding path to the bin directory corresponding to the compiler decompressed into the opt directory. Referring to the following figure, the directory name varies according to the downloaded version of the compiler: 37> 38>  39> 40 41 42 43## 3 Build QEMU Project 44 45### 3.1 Move into QEMU folder 46 47``` 48cd rt-thread/bsp/qemu-vexpress-a9/ 49``` 50 51### 3.2 Configure the environment of Env tool 52 53#### 3.2.1 Remap python command 54 55We need to remap `python` command as python3 by default. 56 57Using `whereis` command to identify your python3's version: 58 59 60 61For instance, as you can see, in my computer, the python3's version is python 3.9. You need to identify python3's version in your computer. Then, we remap the `python` command as python3 by default: 62 63```shell 64sudo rm -rf /usr/bin/python3 65sudo rm -rf /usr/bin/python 66sudo ln -s /usr/bin/python3.9 /usr/bin/python3 67sudo ln -s /usr/bin/python3.9 /usr/bin/python 68``` 69 70### 3.3 Install Env and Configure BSP 71 72Type following the command under `bsp/qemu-vexpress-a9` folder: 73 74``` 75scons --menuconfig 76``` 77 78The Env tool will be installed and initialized after using the `scons --menuconfig` command. Then it will enter the configuration interface, and you could configure the BSP: 79 80 81 82 83 84You can use the keyboard `↑` key and `↓` key to look up and down menu items, use the `Enter` key to enter the selected directory, use the `Space` key to select or cancel bool variables, and press `Esc Esc` to exit the current directory. 85 86> Notice: Please make sure that the terminal size is larger than 80x24 character size. 87 88### 3.4 Configure the QEMU BSP and acquisition of software packages 89 90``` 91source ~/.env/env.sh 92scons --menuconfig 93pkgs --update 94``` 95 96The `env.sh` file is a file that needs to be executed. It configures the environment variables so that we can update the package with the pkgs command and execute it with the `source ~/.env/env.sh` command. 97 98Then use `scons --menuconfig` command to enter menuconfig, and you could select the online packages by this time. 99 100 101 102 103 104For example, select the kernel sample package: semphore sample. 105 106 107 108Exit and save the configuration. 109 110 111 112If you have selected an online package, you can download the package to the packages folder in the BSP directory using the `pkgs --update` command (Git needs to be installed): 113 114 115 116#### 4.1 Tips 117 118Before you use the `pkgs` command, you need to type command `source ~/.env/env.sh`. This is a annoying work. We can attach this command as a new line at the end of `~/.bashrc`, which can let you to to use `pkgs` command directly. 119 120### 3.5 Compile the QEMU project 121 122``` 123scons 124``` 125 126Using the `scons` command to compile the BSP. 127 128 129 130## 4 Introduction of QEMU BSP Catalogue 131 132The board-level support package (BSP) provided by RT-Thread simulates ARM vexpress A9 development board is located in the `qemu-vexpress-a9` folder under the `bsp` directory of RT-Thread source code. This BSP implements LCD, keyboard, mouse, SD card, Ethernet card, serial port and other related drivers. The contents of the folder are shown in the following figure. 133 134 135 136The main files and directories of `qemu-vexpress-a9` BSP are described as follows: 137 138| Fles/Directories | Description | 139| ---------------- | ------------------------------------------- | 140| applications | User application code directory | 141| drivers | The underlying driver provided by RT-Thread | 142| qemu.bat | Script files running on Windows platform | 143| qemu.sh | Script files running on Linux platform | 144| qemu-dbg.bat | Debugging script files on Windows platform | 145| qemu-dbg.sh | Debugging script files on Linux platform | 146| README.md | Description document of BSP | 147| rtconfig.h | A header file of BSP | 148 149## 5 Compile and Run 150 151### 5.1 Use the *scons* Command to Compile the Project 152 153Switch to the QEMU BSP directory and enter the `scons` command to compile the project. If the compilation is correct, the `rtthread.elf` file will be generated in the BSP directory, which is a target file required for QEMU to run. 154 155 156 157### 5.2 Use the *./qemu.sh* Command to Run the Project 158 159After compiling, type `./qemu.sh` to start the virtual machine and BSP project. `qemu.sh` is a Linux batch file. This file is located in the BSP folder, mainly including the execution instructions of QEMU. The first run of the project will create a blank `sd.bin` file under the BSP folder, which is a virtual SD card with a size of 64M. The Env command interface displays the initialization information and version number information printed during the start-up of RT-Thread system, and the QEMU virtual machine is also running. As shown in the following picture: 160 161 162 163### 5.3 Run the Finsh Console 164 165RT-Thread supports Finsh, and users can use command operations in command line mode. 166 167Type `help` or press `Tab` to view all supported commands. As shown in the figure below, commands are on the left and command descriptions are on the right. 168 169 170 171For example, by entering the `list_thread` command, you can see the currently running threads, thread status and stack size; by entering the `list_timer`, you can see the status of the timers. 172 173 174 175### 5.4 Run the File System 176 177Type `list_device` to view all devices registered in the system. You can see the virtual SD card "sd0" device as shown in the following picture. Next, we can format the SD card using the `mkfs sd0` command, which will format the SD card into a FatFS file system. FatFs is a Microsoft fat-compatible file system developed for small embedded devices. It is written in ANSI C, uses abstract hardware I/O layer and provides continuous maintenance, so it has good portability. 178 179> For more information on FatFS, click on the link: [http://elm-chan.org/fsw/ff/00index_e.html](http://elm-chan.org/fsw/ff/00index_e.html) 180 181 182 183The file system will not be loaded immediately after the first formatting of the SD card, and the file system will be loaded correctly only after the second boot. So exit the virtual machine, and then restart the virtual machine and project by entering `./qemu.sh` on the command line interface. Entering `ls` command, you can see that the `Directory` directory has been added, the file system has been loaded, and then you can experience the file system with other commands provided by RT-Thread: 184 185 186 187- ls: Display the file and directory information 188- cd: Switch to the specified directory 189- rm: Delete files or directories 190- echo: Writes the specified content to the target file 191- cat: Displays the details of a file 192- mkdir: Create folders 193 194Please enter `help` to see more commands. 195 196## 6 More Functions 197 198You can configure more functions in the menuconfig's configuration interface. use `scons --menuconfig` to config the BSP. After the configuration is completed, save the configuration first, and then exit the configuration interface, then: 199 2001. If you choose a package, you need to use the command `pkgs --update` to download the package. 2012. Compile with `scons`. 2023. Then enter `./qemu.sh` to run QEMU. 2034. Use `help` to view all commands of the BSP. And then use the commands. 204
