Introduction to embedded Linux BSP

Author: Li Zhimin,Hua Qing vision embedded college lecturer.

An embedded system consists of a hardware environment, an embedded operating system, and applications. The hardware environment is a hardware platform for operating systems and applications to run. It has different requirements with different applications. The diversity of hardware platforms is the main feature of embedded systems. How to Make embedded operating systems run effectively on different hardware platforms is a key issue to be addressed in the development of embedded systems. The solution is to provide a hardware-related layer between the hardware platform and the operating system to shield these hardware differences and provide a unified operating environment for the operating system, this hardware-related layer is the board-level support package (BSP) in the embedded system ).

BSP is the intermediate layer software between the hardware platform and the operating system. It aims to avoid the diversity of underlying hardware and perform direct hardware operations according to the requirements of the operating system, provide the underlying hardware information to the operating system and start the operating system. BSP has the characteristics of hardware relevance and operating system relevance. Its main functions include:

(1) initialize the underlying hardware to provide the underlying hardware information for the operating system;
(2) initialize related hardware devices, mainly storage devices and communication devices;
(3) check whether the system hardware is normal;
(4) load the operating system and start the system to run.

BSP is different from the operating system. different operating systems have different defined forms of BSP, and the functions implemented by BSP are also different. In an embedded Linux system, the underlying hardware is initialized and the operating system is guided. Meanwhile, BSP is related to the hardware, and initialization of the hardware is also considered. These initialization operations are mainly to correctly configure the registers and coprocessor related to CPU, memory, and interrupt. In different development stages, BSP has different tasks to complete because the core and file system are in different locations: in the Development and debugging stage, BSP should be able to communicate with the host and download the core from the host; in the target product, BSP should be able to load the core from non-Easy loss storage devices.