Kvm on Le Site de François

KubeVirt

Mon, 01 Jan 0001 00:00:00 +0000

KubeVirt is a CNCF project that makes Kubernetes a native hypervisor management plane, allowing KVM virtual machines to be declared, scheduled, and operated through the Kubernetes API without a separate virtualisation management layer. The motivating use case is organisational convergence: teams running a mix of legacy VM workloads and modern containerised services no longer need two separate platforms (an OpenStack or vSphere cluster for VMs, a Kubernetes cluster for containers) with separate networking, storage, RBAC, and CI/CD integration. With KubeVirt, both workload types live in the same cluster, share the same kubectl and GitOps tooling, and are subject to the same scheduling, resource quota, and network policy primitives. KubeVirt reached 1.0 in 2023 and is the engine behind Red Hat OpenShift Virtualization, the downstream product used by organisations migrating away from VMware.

KVM/QEMU

Mon, 01 Jan 0001 00:00:00 +0000

KVM (Kernel-based Virtual Machine) and QEMU (Quick Emulator) solve different halves of the same problem and are almost always used together. KVM is a Linux kernel module that turns the kernel into a hypervisor: with Intel VT-x or AMD-V, guest CPUs run on real hardware at near-native speed and guest memory is managed through extended page tables. KVM has no device model of its own — no disk, network, or firmware emulation. QEMU supplies that in userspace (virtio, USB, VGA, ACPI) and controls KVM by issuing ioctl calls on /dev/kvm — creating VMs, mapping memory, running vCPUs via KVM_RUN — while QMP exposes external management over a Unix socket. libvirt, originally from Red Hat, sits above both: it translates domain XML into QEMU command lines and lifecycle operations. The stack is the default on Linux: RHEL ships qemu-kvm, OpenShift Virtualization runs KubeVirt (virt-launcher → libvirt → QEMU), and OpenShift Sandboxed Containers uses Kata Containers with the same hypervisor to isolate pods in micro-VMs.

libvirt

Mon, 01 Jan 0001 00:00:00 +0000

libvirt is an open-source library, daemon, and toolset that provides a unified, stable API for managing virtualisation infrastructure — virtual machines, storage volumes, virtual networks, and host devices — across multiple hypervisor backends. It was originally written by Daniel Berrange at Red Hat and has since become the standard virtualisation management layer on Linux, underpinning KubeVirt, OpenStack Nova, oVirt/RHEV, Proxmox, and the virsh / virt-manager administrative tools. The core value proposition is hypervisor abstraction: the same libvirt API call creates a VM on KVM/QEMU, Xen, LXC, or (historically) VMware ESXi, without the management layer caring about the underlying implementation. In practice, the KVM/QEMU driver is the dominant use case on Linux; the others are progressively less-maintained but remain supported. libvirt communicates with hypervisors through driver-specific mechanisms — with QEMU, it generates the full QEMU command line from the domain XML definition and manages the QEMU process lifecycle, communicating with the running VM through the QEMU Monitor Protocol (QMP) over a Unix socket.