The first chapter of Android Deep Exploration reading notes

The first chapter first introducesAndroidSystem Architecture (Androidis a very good embedded operating system), total is divided into four layers: the first layerLinuxkernel, becauseAndroidis based onLinuxthe kernel, soAndroidwith otherLinuxsystem is no different. This level of this layer mainly includesLinuxdrivers and memory management, process management, power management, and more. The second layer is written in a code base that also includesDALIVKthe runtime of the virtual machine. Third floorAndroid SDKlayer. The fourth tier application (equivalent toAndroidof theUI). And this layer is mainly on the third floorAndroid SDK APIcomplete various functions. The second introduction isAndroidporting (which can be divided into application porting and system porting), where application porting is the application to a specific hardware platform. System porting refers to theAndroidthe system runs on a particular platform. One of the first prerequisites for a system to run on a particular hardware platform is that the operating system supports the hardware platformCPUarchitecture. want toAndroidworks on different hardware platforms and supports onlyCPUarchitecture is not enough and must be madeAndroidvarious hardware that can identify the platform. These efforts are largely dependent onLinuxkernel to complete, which will mostly also die by theLinuxDrive, so that the system is ported in addition to portingCPUarchitecture, the most important thing is portingLinuxDrive. In addition, a hardware abstraction layer is added (HAL,Hardware Abstraction Layer).It then tells the viewLinuxSeveral methods of the kernel version and the definition rules for the version number. Finally, we introduceLinuxdevice drivers. The driver targets the memory peripherals, notCPUNuclear,Linuxmemory and peripherals are divided into character devices, block devices, network equipment, three categories.

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The first chapter of Android Deep Exploration reading notes