用户空间-内核空间

RAM is divided into two distinct regions- the user space and the kernal space.

User Space- It is set of locations where normal user processes run. These processes can’t access kernal space directly. Some part of kernal space can be accessed via system calls.These system calls acts as software interrupts in kernal space.

Kernal Space - kernal runs in the dedicated part of memory. Role of kernal space is to manage applications/ processes running in user space. It can access all the memory. If a process perform a system call, a software interrupt is sent to kernal which then dispatches an appropriate interrupt handler.

https://www.quora.com/What-is-the-difference-between-user-space-and-the-kernel-space