20 October 2008, 09:39

Kernel Log: Coming in 2.6.28 - Part 2: network infrastructure and network drivers

The commit flood for 2.6.28 during the current merge window doesn't look like ending soon – in the last 24 hours alone, Linus Torvalds has integrated a further 700 patches, most of them contributed by other kernel developers, into Linux's main development tree. The changes to ATA support and the block layer were described in a previous kernel log. The networking changes described here found their way into the main tree a few days ago. The network subsystem administrator has even recently been insisting that all changes for the next kernel version should have been in linux-next, the staging tree for new changes, before the merge window was opened – because of this, the main development tree should already include all major network-related changes for Linux 2.6.28.

A rough overview of all the changes can be found in an email sent by Torvalds to pull the networking changes. As expected the developers are integrating five new network drivers:

atl2 – Atheros L2 10/100 Mbit NICs
enic – 10 Gbit NICs from Cisco
jme – Gigabit NICs from JMicron
qlge – 10 Gbit NICs from Qlogic
smsc95xx – USB 2.0 10/100 Mbit adapter with SMSC LAN9500

Unlike many previous kernel versions, no new Wi-Fi drivers are being added to this version. Instead, more popular Wi-fi drivers have been worked on. The ath5k driver for Atheros WLAN chips now supports mesh networks and the Atheros AR2417 v2 chip; the rt2x00 driver now makes use of the encryption technology of various RaLink Wi-Fi chips (1, 2, 3, 4). A number of further improvements to LAN and WLAN drivers can be accessed via the links at the end of this article.

The generic Wireless Regulatory Infrastructure should, in future, be more flexible and better ensure that Wi-Fi hardware does not infringe local rules and regulations on wireless connections. In a change from the previous kernel code, the new infrastructure makes considerable use of a program running in userspace, which can be updated much more easily and rapidly by the distributors than the kernel. Details of how it works and lots of background information on this issue can be found in the commit notes, kernel documentation, an article on LWN.net and a description of the Central Regulatory Domain Agent in the Linux wireless wiki.

The developers have made improvements to the Linux TX multiqueue implementation ("multiqueue networking"), which was introduced in 2.6.27 and have added a "PRIO based multiqueue packet scheduler". Additions to the main development tree include the Phonet Stack (documentation), introduced by Nokia developers, and transparent Ethernet bridging over GRE tunnels from Herbert Xu. Jan Engelhardt has also introduced a number of wide-ranging revisions in the netfilter field, as a result of which Ebtables support is now based on Xtables. After five years of not working, the netfilter infrastructure now once more properly supports transparent proxy support with the developers saying ("Proper transparent proxy support in netfilter. We sort of lost this feature 5 or so years ago, but hey better late than never to get it back :-)").

Other commits in the network infrastructure and drivers include:

Generic:

LAN

Wi-Fi

Further background and information about developments in the Linux kernel and its environment can also be found in previous issues of the kernel log at heise open:

Older Kernel logs can be found in the archives or by using the search function at heise open. (thl/c't)

(djwm)

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