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A kernel implementation of the Point-to-Point Tunnelling Protocols (PPTP) used in VPNs has been added to the network subsystem; according to the relevant commit comment, it is discernibly faster and puts less strain on the CPU than existing user space PPTP stacks. The new kernel functions are accessible via accel-pptp.

With Linux version 2.6.37, the developers have integrated the carl9170 driver for Atheros AR9170 chips into the kernel (for instance 1, 2, 3, 4, 5). These components were previously supported via the ar9170usb and otus drivers. The ar9170usb driver was originally intended to replace the otus driver, which is located in the staging area, but it never managed to match the range of features, speed, stability and quality of otus. Carl9170 has now apparently achieved this, and otus has consequently been thrown out; in the medium term, ar9170usb will probably suffer the same fate.

Network subsystem maintainer David Miller in his main Git-Pull request highlights numerous improvements introduced by Eric Dumazet to optimise routing as well as neighbour and device handling. Due to the changes, routing tests now reportedly run faster with the routing cache disabled.

About the source code management system

Many of the links in this article point to the relevant commits in the web front end of Linus Torvalds' Git source code management system for Linux, because these commits tend to contain a lot more information about the respective changes. The commit comment in the mid-section of the web page displayed by the Git web front end is often a particularly helpful source of further information. This is where the author of a patch usually describes the background and intended effects of the changes.

The bottom section of the Git web front end lists the files that are affected by the patch. The "diff" link behind each file name shows how the patch modifies the respective file; if you want to view the complete patch in its raw form, click on the commitdiff link. Even if you don't have any programming skills the patches are often a good source of information, because they also contain changes to the documentation and comments within the code.


Various other changes affecting the network hardware have been made in the staging area; this is the kernel area for drivers and other independent code which doesn't meet its developers' or the kernel hackers' quality standards. The newly integrated rtl8712 staging driver replaces the rtl8192su driver for USB-802.11n chips by Realtek.

The staging area now includes the brcm80211 open source driver developed by Broadcom for its 802.11n Wi-Fi components. Features such as the support of power management and data encryption techniques have been on the kernel hackers' to-do list since the driver was first introduced back in September. The same applies to transmissions via 40 MHz channels – this is an optional feature of the 802.11n standard which is, however, required to achieve the maximum gross bit rate of 300 Mbits/s.

autofs3 and smbfs have been moved to the staging area because nobody is looking after them; both drivers will probably be thrown out soon unless someone takes on the task of maintaining them. The ti-st (1, 2) and mrst-touchscreen drivers have matured in the staging area and are no longer considered to be lacking in quality; the developers have, therefore, moved them to their proper place in the kernel code.

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