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5.2. Virtualization

5.2.1. Kernel Acceleration for KVM Networking

The VHost Net feature moves the task of converting virtio descriptors to skbs and back from qemu userspace to the kernel driver. This was shown to reduce latency by a factor of five, and improve bandwidth from 90% native to 95% of native on some systems.
This feature is activated by using -netdev options (instead of -net) and adding the vhost=on flag.
For more information, refer to

5.2.2. KVM Stable PCI Addresses

KVM guests in Fedora now have stable PCI addresses, reducing the chance that Windows guests will require reactivation as guest configuration is modified.
KVM guest virtual machine devices retain their PCI address allocations as other devices are added or removed from the guest configuration.

5.2.3. Virt x2apic

X2apic improves guest performance by reducing the overhead of APIC access, which is used to program timers and for issuing inter-processor interrupts. By exposing x2apic to guests, and by enabling the guest to utilize x2apic, we improve guest performance.
Fedora 13 supports x2apic in both the host and guest roles.
For more information, refer to

5.2.4. Virtio-Serial

The virtio-console pci device is now equipped to handle multiple console ports as well as generic ports for guests running on top of qemu and KVM. This facilitates simple communication between guest and host.

5.2.5. Virtualization Technology Preview Repo

The Virtualization Preview Repository exists for people who would like to test the very latest virtualization-related packages. This repo is intended primarily as an aid to testing and early experimentation. It is not intended for deployment on production systems.

5.2.6. Xen Kernel Support

The kernel package in Fedora 13 supports booting as a guest domU, but will not function as a dom0 until such support is provided upstream.
The most recent Fedora release with dom0 support is Fedora 8.
Booting a Xen domU guest within a Fedora 13 host requires the KVM-based xenner. Xenner runs the guest kernel and a small Xen emulator together as a KVM guest.

Important — Suitable hardware required

KVM requires hardware virtualization features in the host system. Systems lacking hardware virtualization do not support Xen guests at this time.