100 lines
6.5 KiB
Markdown
100 lines
6.5 KiB
Markdown
# LiteOS Cortex-A<a name="EN-US_TOPIC_0000001096612501"></a>
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- [Introduction](#section11660541593)
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- [Directory Structure](#section161941989596)
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- [Constraints](#section119744591305)
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- [Usage](#section741617511812)
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- [Preparations](#section1579912573329)
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- [Source Code Acquisition](#section11443189655)
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- [Compilation and Building](#section2081013992812)
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- [Repositories Involved](#section1371113476307)
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## Introduction<a name="section11660541593"></a>
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The OpenHarmony LiteOS Cortex-A is a new-generation kernel developed based on the Huawei LiteOS kernel. Huawei LiteOS is a lightweight operating system \(OS\) built for the Internet of Things \(IoT\) field. With the rapid development of the IoT industry, OpenHarmony LiteOS Cortex-A brings small-sized, low-power, and high-performance experience and builds a unified and open ecosystem for developers. In addition, it provides rich kernel mechanisms, more comprehensive Portable Operating System Interface \(POSIX\), and a unified driver framework, Hardware Driver Foundation \(HDF\), which offers unified access for device developers and friendly development experience for application developers. [Figure 1](#fig27311582210) shows the architecture of the OpenHarmony LiteOS Cortex-A kernel.
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**Figure 1** Architecture of the OpenHarmony LiteOS Cortex-A kernel<a name="fig27311582210"></a>
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## Directory Structure<a name="section161941989596"></a>
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```
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/kernel/liteos_a
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├── apps # User-space init and shell application programs
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├── arch # System architecture, such as ARM
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│ └── arm # Code for ARM architecture
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├── bsd # Code of the driver and adaptation layer module related to the FreeBSD, such as the USB module
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├── compat # Kernel API compatibility
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│ └── posix # POSIX APIs
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├── drivers # Kernel drivers
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│ └── char # Character device
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│ ├── mem # Driver for accessing physical input/output (I/O) devices
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│ ├── quickstart # APIs for quick start of the system
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│ ├── random # Driver for random number generators
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│ └── video # Framework of the framebuffer driver
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├── fs # File system module, which mainly derives from the NuttX open-source project
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│ ├── fat # FAT file system
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│ ├── jffs2 # JFFS2 file system
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│ ├── include # Header files exposed externally
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│ ├── nfs # NFS file system
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│ ├── proc # proc file system
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│ ├── ramfs # RAMFS file system
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│ └── vfs # VFS layer
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├── kernel # Kernel modules including the process, memory, and IPC modules
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│ ├── base # Basic kernel modules including the scheduling and memory modules
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│ ├── common # Common components used by the kernel
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│ ├── extended # Extended kernel modules including the dynamic loading, vDSO, and LiteIPC modules
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│ ├── include # Header files exposed externally
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│ └── user # Init process loading
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├── lib # Kernel library
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├── net # Network module, which mainly derives from the lwIP open-source project
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├── platform # Code for supporting different systems on a chip (SOCs), such as Hi3516D V300
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│ ├── hw # Logic code related to clocks and interrupts
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│ ├── include # Header files exposed externally
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│ └── uart # Logic code related to the serial port
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├── platform # Code for supporting different systems on a chip (SOCs), such as Hi3516D V300
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├── security # Code related to security features, including process permission management and virtual ID mapping management
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├── syscall # System calling
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└── tools # Building tools as well as related configuration and code
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```
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## Constraints<a name="section119744591305"></a>
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- Programming languages: C and C++
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- Applicable development boards: Hi3518E V300 and Hi3516D V300
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- Hi3518E V300 uses the JFFS2 file system by default, and Hi3516D V300 uses the FAT file system by default.
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## Usage<a name="section741617511812"></a>
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OpenHarmony LiteOS Cortex-A supports the [Hi3518E V300](https://gitee.com/openharmony/docs/blob/master/en/device-dev/quick-start/quickstart-lite-introduction-hi3518.md) and [Hi3516D V300](https://gitee.com/openharmony/docs/blob/master/en/device-dev/quick-start/quickstart-lite-introduction-hi3516.md). You can develop and run your applications based on both development boards.
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### Preparations<a name="section1579912573329"></a>
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You need to set up the compilation environment on Linux.
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- [Compilation environment on Linux](https://gitee.com/openharmony/docs/blob/master/en/device-dev/quick-start/quickstart-lite-env-setup-lin.md)
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- For Hi3518E V300, see [Setting Up the Hi3518 Development Environment](https://gitee.com/openharmony/docs/blob/master/en/device-dev/quick-start/quickstart-lite-steps-board3518-setting.md).
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- For Hi3516D V300, see [Setting Up the Hi3516 Development Environment](https://gitee.com/openharmony/docs/blob/master/en/device-dev/quick-start/quickstart-lite-steps-board3516-setting.md).
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### Source Code Acquisition<a name="section11443189655"></a>
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Download and decompress a set of source code on a Linux server to acquire the [source code](https://gitee.com/openharmony/docs/blob/master/en/device-dev/get-code/sourcecode-acquire.md).
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### Compilation and Building<a name="section2081013992812"></a>
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For details about how to develop the first application, see:
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- [Developing the First Example Program Running on Hi3518](https://gitee.com/openharmony/docs/blob/master/en/device-dev/quick-start/quickstart-lite-steps-board3518-running.md)
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- [Developing the First Example Program Running on Hi3516](https://gitee.com/openharmony/docs/blob/master/en/device-dev/quick-start/quickstart-lite-steps-board3516-running.md)
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## Repositories Involved<a name="section1371113476307"></a>
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[Kernel subsystem](https://gitee.com/openharmony/docs/blob/master/en/readme/kernel.md)
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[drivers\_liteos](https://gitee.com/openharmony/drivers_liteos/blob/master/README.md)
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**kernel\_liteos\_a**
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