Hardware Support: A Summary
Explore the key hardware support needed for operating system virtualization focused on address translation. Understand privileged CPU modes, base and bounds registers, and how the hardware handles virtual address translation and exceptions to protect memory access. This lesson helps you grasp the hardware features that enable secure and efficient virtualization.
Let us now summarize the support we need from the hardware (see figure below).
Privileged mode
First, as discussed in the chapter on CPU virtualization, we require two different CPU modes. The OS runs in privileged mode (or kernel mode), where it has access to the entire machine; applications run in user mode, where they are limited in what they can do. A single bit, perhaps stored in some kind of processor status word, indicates which mode the CPU is currently running in; upon certain special occasions (e.g., a system call or some other kind of ...