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Like its predecessors, Fedora 13 uses the KVM hypervisor. However, the PCI addresses of virtual hardware components such as graphic cards, storage adaptors or network interfaces visible in KVM guest systems are now designed to remain the same when a device is added to, or removed from, the virtual hardware configuration. Some versions of Windows regarded the changes previously triggered by the smallest modification to the hardware configuration as important enough to warrant a reactivation request.

The virtual x2apic feature is designed to improve performance, particularly in guest systems with multiple CPUs. VirtioSerial, on the other hand, is designed to simplify the communication between guest systems and their host. The kernel of Fedora 13 also includes vhost-net, which was integrated in Linux 2.6.34 – roughly described in the commit comment in the main development branch of Linux, this is a server for the Virtio framework which works at kernel level and is designed to reduce overheads when guest systems transfer data to other machines via the virtual Virtio network hardware. The features page in the Fedora wiki states that VHost-Net decreased the latency fivefold on a test system and, compared to running directly on the hardware, increased data throughput from 90% to 95%.

Updates galore

At Fedora 13's time of release, the (SRPMS/x86-32/x86-64/) and (SRPMS/x86-32/x86-64/) update package repositories already contain numerous updates which have been released or are in preparation. These corrections have not been integrated into the distribution, which was already finalised last week and has since been deployed to the mirrors, to avoid introducing new bugs just before the release of the new version.

These updates are probably only the first few of the flood of updates customary in Fedora, because, unlike many mainstream distributions, the Fedora project releases updates not only to fix bugs or security holes, but also to deploy new versions of the software contained in Fedora. Fedora 12, which is now six months old, has so far been given nearly 4,000 updates – decidedly more than other distributions.

Fedora updates frequently also include jumps from one kernel version in the main development branch to the next. For instance, Fedora 12, which was originally released with kernel version 2.6.31, was already updated to Linux 2.6.32 several months ago, but it hasn't been given the version 2.6.33 kernel used in Fedora 13; an update to the recently released Linux version 2.6.34 is already being prepared. To avoid presenting users with a frozen system in case of a kernel problem, the new kernel is always installed in parallel with the current one, and previous kernels are only uninstalled as part of subsequent updates.

As the new kernel version in the main development line includes numerous infrastructure improvements as well as a large number of new and improved drivers, the updated version of Fedora 12 supports various hardware components introduced in the past few months which were unavailable in the distribution's original release. This distinguishes Fedora from mainstream desktop distributions such as openSUSE or Ubuntu, where new kernel versions or drivers are not deployed as regular updates – as a result, those who don't want to switch to a developer version of their distribution sometimes have to wait for months until new hardware components are supported by the next main release with a more recent kernel.

Core matters

The kernel in Fedora 13 is based on Linux version A kernel with a workaround for the performance weakness in AMD's new Phenom X6 processors with Turbo Core and numerous other corrections is deployed with the first updates. Compared to their fellow distributors, the Fedora developers have integrated only a very few changes into their kernel; among the major changes is the support of Evergreen graphics chips on Radeon HD 5000 graphics cards, the crystalhd staging driver and various updates for DRM and V4l/DVB drivers as well as a few further patches which are part of the recently released Linux 2.6.34 or due to be integrated into version 2.6.35.

Major patches in the Fedora kernel unlikely to make it into the main development branch of Linux any time soon include the Utrace userspace tracing framework and the kernel drivers and infrastructure for LIRC, which is required for some infra-red remote controls. The Fedora kernel does not support operation as a controlling Xen domain (Dom0).

As in previous versions of Fedora, the developers have omitted most of the drivers in the kernel's staging area. This causes Fedora's Wi-Fi support to be slightly inferior in comparison with openSUSE or Ubuntu, because Wi-Fi chips such as Realtek's 8187SE, 8192SU, RTL8192E or RTL8192U are only supported via staging drivers, which are missing in Fedora. Furthermore, only a few kernel drivers, and these still in need of tweaking, are available for Ralink series RT2860 and RT2870 chip-sets and their successors. Ralink's own drivers, which work slightly better, but sometimes cause problems with the NetworkManager, are available via RPM Fusion. This repository also offers a driver package which includes numerous other staging drivers – for instance various drivers which are related to Ralink's proprietary drivers as well as some drivers for the Realtek Wi-Fi chip-sets mentioned above.

Like previous versions of Fedora, Goddard still uses a variant of GRUB 0.97 as its default boot manager; those who want to experiment with the current pre-release version of GRUB 2 can find it in the package repositories.

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