(Android dedicated drivers form the pillar of Android runtime. Technically, the Android dedicated driver is also the highlight of the entire Android system, especially the Binder driver. Binder is an interprocess communication mechanism (IPC). Compared with the traditional IPC mechanism, the biggest attribute of Binder is efficiency, because communication data only needs to be replicated once between two processes. Binder is widely used in Android system. When it comes to large communication data, Binder is generally used in combination with another driver Ashmem. Ashmem is a shared memory driver. Compared with traditional shared memory, the biggest attribute of Ashmem is that it is described through a file descriptor and can be dynamically partitioned. The purpose of dynamic block management is to return some memory that is no longer used to the system, which is very suitable for mobile devices with small memory. The other special driver, Logger, is a log driver. Compared with the traditional log system, the attribute of Logger is that logs are recorded in the kernel space rather than in files, which can improve the log reading and writing speed. This PPT talks about the implementation principles of Logger, Binder and Ashmem, three Android specific drivers. Because these three drivers are widely and frequently used in Android source code, we can grasp the essence of Android by understanding their implementation principles. This is also very helpful for reading other codes of Android system in the future.)
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