Source code based on: Linux 5.4
0. Preface
ION was introduced by Google in Android 4.0. The main purpose is to realize zero-copy shared memory between devices by allocating and sharing memory between hardware devices and user space. It is mostly used for multimedia, such as camera, display, graphic, etc. ION is a memory manager that manages different types of memory heaps (heap), and different types of memory are allocated through different memory allocators, such as cma, kmalloc, vmalloc, etc.
to be continued