KVM vs Xen Project Hypervisor

KVM is an open-source virtualization solution for Linux hosts with Intel VT or AMD-V extensions. It runs multiple virtual machines using unmodified Linux or Windows images, each with virtualized hardware such as a network card, disk, and graphics adapter. The documented capabilities include live migration, nested guests, CPU and PCI hotplug, virtio devices, and device assignment; snapshots and GPU acceleration are also listed. KVM’s kernel component is part of mainline Linux, while its userspace component is part of mainline QEMU. Linux distributions commonly package the required modules and tools, and Windows guest drivers are available separately. Documented processor coverage includes Intel, AMD, ARM, PowerPC, and 64-bit S390 systems. KVM can be used with upper layers including QEMU, libvirt, OpenStack, and oVirt. It is available for Linux and self-hosted use, and the listed plan is free. The host must have Intel VT or AMD-V virtualization extensions.

Xen Project Hypervisor is a free, open-source type-1 hypervisor that runs multiple operating systems on one host. The project describes uses including server and desktop virtualization, IaaS, embedded systems, security applications, and hardware appliances. Linux is the most common control stack; NetBSD and FreeBSD are also named as host options. Xen’s microkernel design has a small memory footprint and restricts the interface exposed to guests. It can run a system’s main device driver inside a VM, allowing that VM to be restarted after a driver crash or compromise without affecting the rest of the system. On x86, fully paravirtualized guests can run without virtualization extensions. Listed capabilities include snapshots, nested virtualization, and GPU acceleration. The separate XAPI toolstack supports multi-host management, snapshots and migration, resource pools, storage migration, Open vSwitch, event tracking, upgrades, patching, and monitoring. Its built-in guest support and templates cover Windows and Linux. Downloads are source releases for building, packaging, and platform integration.