In association with heise online

Ralink WLAN

Developers have added experimental support for Ralink's RT5390 WLAN chip to the rt2800pci driver. This is currently considered "non-functional" and for the time being is aimed squarely at testers and developers. As with the Realtek drivers, the situation for drivers for Ralink WLAN components is set to improve – as reported some weeks ago in a blog posting by Greg Kroah-Hartman, the company has recently been working directly on the drivers produced by the Rt2x00 project, which have long been included in the kernel. Like Realtek, Ralink had for some time been developing its own drivers, the poor quality of which meant, however, that they never made it past the staging zone.

The Rt2x00 project drivers arose largely independently of the drivers developed by Ralink. The former now support most chips just as well, if not better. The rt2860sta and rt2870sta staging drivers for Ralink WLAN chips are therefore likely to exit the kernel in 2.6.40, as they address WLAN components which are now supported by the Rt2x00 driver (1, 2). Users still experiencing problems with the latter, and consequently employing one of the two staging drivers, should report these problems to the kernel development team as soon as possible, so that they can be resolved or the removal of the staging drivers deferred.

WLAN drivers

As in 2.6.37 and 2.6.38, kernel hackers have further developed the b43 driver code for addressing Broadcom 802.11n chips, with the result that the driver also now addresses third generation 802.11n PHYs (see e.g. 1, 2). A good overview of which Broadcom chips the driver is now able or better able to address can be gleaned from the updated wiki page on the driver and the changes made since mid March. The BCM4321 and BCM4322 components are among the chips now partly supported. The driver is still unable to address the BCM4313, BCM43224 and BCM43225 components. The wiki page also lists the chips addressed by the proprietary wl driver and by Broadcom's own staging drivers.

The iwlwifi driver now supports Intel 2000 series WLAN chips (see e.g. 1, 2). To make this WLAN driver for newer Intel WLAN chips easier to maintain, the developers have hived off support for IPW3945 (802.11g) and IPW4965 (802.11n) series chips to a new iwlegacy driver.

The ar9170usb driver for some Atheros USB chips is to exit the Kernel in 2.6.40, as it is being replaced by the carl9170 driver that was merged into 2.6.37.

In Brief

  • Following on from the basic infrastructure for operating as a Xen host (Dom0), merged into 2.6.37, kernel 2.6.39 sees the addition of the network backend used by frontend drivers in Xen guests (DomU) to communicate with other systems. The storage backend is still outstanding, so that it remains impossible to run as Dom0 in any meaningful way without installing further patches.
  • Packet scheduler CHOKe ("CHOose and Kill" or "CHOose and Keep") has been merged into the network stack. It is based on the Random Early Detection (RED) algorithm and is primarily of interest for allowing routers and bridges to avoid congestion and jams. More information can be found in the LWN.net article "The CHOKe packet scheduler". Also new is the Stochastic Fair Blue (SFC) scheduler, which takes up ideas from a 1999 research paper "BLUE: A New Class of Active Queue Management AlgorithmsPDF".
  • The Bluetooth code now supports Low Energy (LE) connections, defined in version 4.0 of the Bluetooth-specification. There is also a new Bluetooth driver for Texas Instruments' WiLink7, btwilink. Nokia developers have also introduced a whole series of minor enhancements to the Bluetooth code, links to which can be found in the 'Minor Gems' section of this article.
  • From 2.6.39, the network stack will offer mechanisms for outsourcing QoS (quality of service) tasks to hardware.
  • The kernel will in future allocate names beginning with "eth" to USB network chips with a globally unique MAC address. The prefix 'usb' will continue to be used for other chips generally used for point to point communication.
  • USB NIC driver smsc95xx now also supports LAN9530, LAN9730 and LAN89530 SMSC chips.
  • Texas Instruments' wl12xx driver for wl1271 and wl1273 WLAN chips now supports operation as an access point (AP) (see e.g. 1, 2, 3, 4, 5).
  • The C_CAN driver for Bosch's C_CAN Controller, used in some ST Microelectronics products, has been merged into the kernel.
  • Kernel hackers have added support for IPsec extended sequence numbers (ESN), as specified in RFC 4303, to the functions responsible for Encapsulating Security Payload (ESP) (1, 2).

Network subsystem maintainer David Miller lists a number of further enhancements in his git pull requests sent out during the merge window (1, 2, 3), in which he rates ipset support as "totally awesome" and elucidates a number of changes to the routing infrastructure. These include changes to the code for routing statistics which modify locking behaviour, thereby improving scalability. 2.6.37 and 2.6.38 also included enhancements in this area.

Next: Minor gems

Print Version | Permalink: http://h-online.com/-1227053
  • Twitter
  • Facebook
  • submit to slashdot
  • StumbleUpon
  • submit to reddit
 


  • July's Community Calendar





The H Open

The H Security

The H Developer

The H Internet Toolkit