What's changed: Initial version (topic 2.05, subtopics 2.05.1–2.05.2)
5.1How Virtual Machines Work and KVM
Learn the difference between host-type and hypervisor-type virtualization (KVM, VirtualBox, Xen), how CPU/memory/storage/network virtualization works, the role of QEMU, hardware virtualization support (vmx/svm) checked via /proc/cpuinfo/lscpu, the kvm-intel/kvm-amd kernel modules, lifecycle management via libvirtd, virt-manager, and bridge-utils.
Running several independent OS instances on one physical server—virtualization—is core Linux infrastructure, from spinning up test environments to consolidating a data center. LinuC-2 centers on KVM, Linux's native hypervisor, and how it "fakes" CPU, memory, storage, and network resources for guests.
5.1.1Host-type vs hypervisor-type
- Host-type virtualization installs the hypervisor as an application on top of an existing OS (e.g., VirtualBox). Easy to set up, but the host OS adds overhead.
- Hypervisor-type virtualization controls hardware directly. On Linux, KVM runs as part of the kernel itself, giving each guest OS an isolated execution environment. Xen is a different approach with its own dedicated hypervisor layer.
- KVM (Kernel-based Virtual Machine) is a set of kernel modules that turn the Linux kernel itself into a hypervisor; guests are scheduled as ordinary Linux processes.
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