"Android Deep Exploration" (Vol. 1) Hal and Driver development

Chapter One: An overview of Android system porting and driver development

This chapter mainly introduces the main contents of Android driver development and system porting, and makes an overall introduction to the Android and Linux drivers. Through the study of the first chapter, I have a perceptual understanding of Linux driver development. In the process of learning, first of all, I learned through the previous lessons of knowledge and access to information about the meaning of some professional vocabulary (for example:. So file: Shared library, is a sharer object for dynamic connection; SDK: Software development Kit; API: Application Programming Interface , HAL: Hardware abstraction layer, etc.), laying the foundation for better learning of Android Drive development later.

Secondly, on the premise of understanding some professional foundation, through the first chapter of the study I learned that, at present, the Android system has formed a very complete architecture, mainly including the Linux kernel, core library and environment (c + + code base and runtime), the Android Software Development Kit (application framework) and applications.

Android porting can be divided into two parts: application porting and system porting. This book is mainly about system porting, which means having the Android operating system run on a particular hardware platform. Doing so requires the operating system to support the CPU architecture of the hardware platform and to allow Android to recognize the various hardware on the platform. Therefore, in addition to porting the CPU architecture, the most important thing is to migrate Linux drivers. In addition to Linux-driven porting, the Android system is also unique to the HAL hardware abstraction layer, which is located between the Android and Linux systems and plays a role when Android accesses Linux. In this respect, the Android transplant is divided into Linux-driven porting and Hal porting.

We all know that Android is based on the Linux kernel, because Linux is always open source, so the Linux kernel-based android is also known as open source, so once launched by the vast number of programmers and mobile phone manufacturers favor. But Android's "semi-masked" aspect of open source has been explained in the context of Android's development history.

For example, all hardware drivers written for Android cannot be merged into kernel. These drivers are only valid in Google Code and are not available at all in kernel.  It is for this reason that Google never submits a lot of hardware drivers and platform source code to kernel. Since the hardware vendors are not open source driver code, for our survival in the Android low-level developers, especially those engaged in the drive development of the members, has brought huge employment opportunities. We can get paid for the development of non-open source drivers for hardware vendors, and with the exception of Android, there are many companies that are recruiting Android-driven developers. Thus, the drive of non-open source to our learning has brought difficulties, but also for the future employment opportunities to increase weight.

Http://www.cnblogs.com/Mr-zsj/p/5413596.html

"Android Deep Exploration" (Vol. 1) Hal and Driver development