LiteOS Cortex-A

• Introduction

• Directory Structure

• Constraints

• Usage

  • Preparations
  • Source Code Acquisition
  • Compilation and Building

• Repositories Involved

Introduction

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 shows the architecture of the OpenHarmony LiteOS Cortex-A kernel.

Figure 1 Architecture of the OpenHarmony LiteOS Cortex-A kernel

Directory Structure

/kernel/liteos_a
├── apps                   # User-space init and shell application programs
├── arch                   # System architecture, such as ARM
│   └── arm                # Code for ARM architecture
├── bsd                    # Code of the driver and adaptation layer module related to the FreeBSD, such as the USB module
├── compat                 # Kernel API compatibility
│   └── posix              # POSIX APIs
├── drivers                # Kernel drivers
│   └── char               # Character device
│       ├── mem            # Driver for accessing physical input/output (I/O) devices
│       ├── quickstart     # APIs for quick start of the system
│       ├── random         # Driver for random number generators
│       └── video          # Framework of the framebuffer driver
├── fs                     # File system module, which mainly derives from the NuttX open-source project
│   ├── fat                # FAT file system
│   ├── jffs2              # JFFS2 file system
│   ├── include            # Header files exposed externally
│   ├── nfs                # NFS file system
│   ├── proc               # proc file system
│   ├── ramfs              # RAMFS file system
│   └── vfs                # VFS layer
├── kernel                 # Kernel modules including the process, memory, and IPC modules
│   ├── base               # Basic kernel modules including the scheduling and memory modules
│   ├── common             # Common components used by the kernel
│   ├── extended           # Extended kernel modules including the dynamic loading, vDSO, and LiteIPC modules
│   ├── include            # Header files exposed externally
│   └── user               # Init process loading
├── lib                    # Kernel library
├── net                    # Network module, which mainly derives from the lwIP open-source project
├── platform               # Code for supporting different systems on a chip (SOCs), such as Hi3516D V300
│   ├── hw                 # Logic code related to clocks and interrupts
│   ├── include            # Header files exposed externally
│   └── uart               # Logic code related to the serial port
├── platform               # Code for supporting different systems on a chip (SOCs), such as Hi3516D V300
├── security               # Code related to security features, including process permission management and virtual ID mapping management
├── syscall                # System calling
└── tools                  # Building tools as well as related configuration and code

Constraints

• Programming languages: C and C++
• Applicable development boards: Hi3518E V300 and Hi3516D V300
• Hi3518E V300 uses the JFFS2 file system by default, and Hi3516D V300 uses the FAT file system by default.

Usage

OpenHarmony LiteOS Cortex-A supports the Hi3518E V300 and Hi3516D V300. You can develop and run your applications based on both development boards.

Preparations

You need to set up the compilation environment on Linux.

• Compilation environment on Linux
• For Hi3518E V300, see Setting Up the Hi3518 Development Environment.
• For Hi3516D V300, see Setting Up the Hi3516 Development Environment.

Source Code Acquisition

Download and decompress a set of source code on a Linux server to acquire the source code.

Compilation and Building

For details about how to develop the first application, see:

• Developing the First Example Program Running on Hi3518

• Developing the First Example Program Running on Hi3516

Repositories Involved

Kernel subsystem

drivers_liteos

kernel_liteos_a