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08 January 2010, 11:01

Kernel Log: Coming in 2.6.33 (Part 1) - Networking

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Kernel Log Logo by Thorsten Leemhuis

Linux 2.6.33 will have new and improved drivers for Wi-Fi chips by Intel, Ralink and Realtek. Several drivers for old Wi-Fi hardware have been moved to the staging area and will probably soon be discarded. New additions include various LAN chip drivers and several improvements to the network stack.

On Tuesday night, Linus Torvalds released Linux 2.6.33-rc3, the third release candidate of Linux version 2.6.33. The forthcoming version is expected to be finalised in early March and this release candidate offers a smaller number of changes than is usual at this point in the development cycle – it seems that some of the kernel hackers took some time off over Christmas.

However, most of the important new features of the next version in the Linux main development line were already integrated by Torvalds and his fellow programmers in the "merge window" phase at the start of the development cycle. As it is uncommon for newly integrated items to be discarded again in the current second phase, the Kernel Log can already provide a comprehensive overview of the most important new features of Linux 2.6.33.

To avoid being swamped by the wealth of advancements, the Kernel Log will provide the overview in its usual multi-part series of articles that together discuss the kernel's various functional areas. The first part of the "Coming in 2.6.33" series deals with the most important changes to the kernel's network support. Articles discussing the Linux kernel's storage hardware, file systems, graphics support, architecture code, drivers and other functional areas will follow over the next few weeks preceding the release of version 2.6.33 of the Linux kernel.


The iwlwifi driver can now address various, previously unsupported Intel series 1000, 5000 and 6000 Wi-Fi modules (123) and now also supports the WiMAX function of the 6x50 series (12). A new addition is the "Intel Wireless MultiCom 3200 top driver (iwmc3200top)" for a new Intel wireless chip that supports GPS, Bluetooth, Wi-Fi and WiMAX. The power saving features of the iwl3945 Intel Wi-Fi driver have been temporarily disabled due to some problems.

The kernel developers have also added the rt2800pci driver, which is still considered "very experimental", "intended for developers" and "non-functional" at this point in the development cycle and addresses Ralink's RT2760, RT2790, RT2860, RT2880, RT2890 and RT3052 PCI Wi-Fi chips frequently found in recent netbooks and notebooks. These chips could previously only be used with a driver developed by the vendor which was in the kernel's staging area for a few months. The staging area is the kernel area for drivers of insufficient quality or maturity. However, some distributions don't include the staging drivers and the drivers, with their separate Wi-Fi stack, occasionally have problems when interacting with configuration tools, such as the Network Manager. So the Ralink drivers, although not a proper solution, were better than nothing. Initially it's likely the situation will be the same for the rt2800pci driver.

The new driver was mainly developed by the rt2x00 project which also maintains other drivers for Ralink chips. Several more of the project's drivers were improved for 2.6.33 and now support a greater variety of USB Wi-Fi hardware than ever – more details can be found via the links mentioned under "Minor gems" at the end of this article. The new support of Ralink's RT3070 Wi-Fi chip in the rt2800usb driver is also classified as "non-functional at the moment" – but the developers have already prepared patches for the two rt2800 drivers which could still make it into 2.6.33 and get the drivers into a "usable state".

The kernel hackers have incorporated the rtl8192u driver for Realtek's chips of the same name into the staging area. Furthermore, the arlan, netwave, strip and wavelan drivers have been moved to the area for low-quality drivers because they are based on the Linux kernel's MAC80211 Wi-Fi stack and, according to the kernel developers, are now hardly used by anyone – therefore, they are currently not considered worth the effort of porting them to the new Wi-Fi stack. If no one comes forward to maintain these drivers they are destined to be removed in Linux 2.6.35.

LAN, network stack etc

Further changes in the network subsystem:

  • The sfc driver now supports the SFL9021 'Siena' and SFC9020 'Bethpage' 10 Gigabit ethernet controllers from Solarflare's SFC9000 series (12).
  • A new addition is the octeon_mgmt LAN driver for CN57XX, CN56XX, CN55XX, CN54XX, CN52XX and CN6XXX Octeon chips by Cavium Networks.
  • The bnx2x driver now also supports Broadcom's BCM8481/BCM84823 and BCM84823 chips (12) and offers extended iSCSI support when combined with the cnic driver (123).
  • The new recvmmsg socket syscall allows multiple messages to be received, which reduces processing workloads (see also the short description at
  • The new TCP Cookie TransactionsPDF are designed to make initialising TCP connections faster, more secure and more robust (1234567).

The first Git-Pull request by network subsystem maintainer David S. Miller alone caused more than 1800 changes to be integrated into Linux 2.6.33 – this means that about a fifth of all the commits incorporated during the merge window of 2.6.33 have been handled by Miller, who also maintains the old IDE subsystem and the Sparc code. While the majority of changes modify C source code, some of the changes adapt the firmware that comes with the kernel and considerably increase the total number of new, deleted or moved lines of source code – this is very evident with two patches of about 1 MB each which update the firmware of the bnx2x driver (12).

Minor gems

Many further minor, but by no means insignificant, changes can be found in the list below, which contains the commit headers referring to the respective change. Like many of the references in the text above, the links point to the relevant commit in the web front end of the Git branch for the kernel sources maintained by Linus Torvalds at The commit comments and the patches themselves provide extensive further information on the respective changes.



Various others network drivers, network stack

For other articles on 2.6.33 and links to the rest of the "Coming in 2.6.33 " series, see The H's Kernel Log - 2.6.33 Tracking page.

(thl /c't).


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