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Among the changes the developers have integrated into Linux 3.0 is the storage backend for Xen (for example 1, 2, 3). This means that the kernel has finally acquired all the essential components for hosting guest systems as a Dom0 together with the Xen hypervisor.

Background information on this is available in various Xen-related blog postings (1, 2, 3, 4, 5, 6). However, the code that has been integrated into the kernel is a substantially cut-down and revised version of the code that is currently used in commercial Xen products such as the Xen Server. Hence, the 3.0 kernel with the Xen hypervisor doesn't, for example, offer to pass through USB devices to guests, and Suspend-to-RAM doesn't work either.


The Radeon DRM/KMS driver now supports the graphics core in Llano processors, which AMD recently launched for notebooks and desktop PCs (see 1, 2). To prevent such problems as blank screens, audio output via HDMI has been temporarily disabled by default in the driver, but can be switched on again by using the kernel parameter In addition, a change in the help text for the Radeon DRM/KMS driver now makes it clear that it supports all Radeon graphics hardware.

The i915-DRM/KMS driver in Linux 3.0 – for Intel graphics chips in processors and chipsets for notebooks and desktop PCs – reportedly already controls the graphics core in Ivy Bridge processors, which Intel will probably not launch until the beginning of next year (see 1, 2, 3, 4, 5, 6, 7). The Nouveau DRM/KMS driver got changes that lay the foundations for supporting various techniques involved in switching between processor/chipset graphics and GeForce graphics chips (see 1, 2, 3); NVIDIA calls it "Optimus" in recent notebooks.


The netfilter code now includes a "Berkeley Packet Filter Just-in-Time Compiler" for x86-64 systems. It generates assembler code at rumtime that carries out some of the network packet filtering tasks set by sniffer tools such as Tcpdump. Disabled by default, the JIT compiler can be enabled by writing "1" into the /proc/sys/net/core/bpf_jit_enable file; when testing an earlier version of the compiler, its developer managed to measure savings of 50 nanoseconds per packet.

The kernel's Wi-Fi stack will offer "basic" Wake on Wireless LAN (WoWLAN) configuration support (1, 2). Another new addition is the rtl8192se driver for Realtek's RTL8191SE and RTL8192SE PCIe Wi-Fi chips (for example 1). From Linux 3.0, the kernel drivers the developers create for Ralink Wi-Fi chips within the Rt2x00 project will offer experimental support for series RT5370 USB Wi-Fi chips. The driver for the RT53xx family continues to be classified as experimental, but it is now said to fully support these PCI Wi-Fi chips and to work better. The situation is similar with the drivers for series RT33xx PCI and USB chips, which no longer have "experimental" status. The drivers for Ralink chips have now matured far enough for the kernel developers to throw out the rt2860sta and rt2870sta drivers that were developed by Ralink and were later integrated into the staging branch.

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