ION is the memory manager of Android, it could be used by graphic and multimedia stacks to allocate buffers.
ION include a buffer sharing mechanism between process and drivers.
ION define opaque handles to manage underline buffers.
ION handles are only map in kernel if that is needed by drivers, it help to save logical address space.
In a same way ION handles aren't mmaped by default in userland but all helpers functions are provided.
i cant understand the things?
why need ion instad of pmem?
can some1 tell?