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See also: last week's Kernel page.

Kernel development


The current development kernel release is 2.3.22. A number of problems have been reported with this kernel, so potential users may wish to approach it with caution. The "testing" directory contains a 2.3.23 prepatch (up to version 4 as of this writing) that should probably be applied; it fixes the 2.3.22 difficulties. (Of course, 2.3.23 may be out by the time you read this; see the LWN daily updates page for the latest information).

The current stable kernel release is 2.2.13, released at long last. A set of release notes for this version has been posted by Alan Cox. Therein one can read the (long) list of changes incorporated into this release of the kernel.

If 2.2.13 proves as stable as hoped, there is a good chance that the next release (2.2.14) will contain the long-awaited NFS server patches.

Version 0.0.2 of the ext3 journaling filesystem has been released by Stephen Tweedie. See the announcement for details; this is, according to Stephen, "the first usable release." Note that if you want to test out ext3, that there are a couple of patches to 0.0.2 in the FTP area which should be applied as well.

Stephen has also released an initial set of tools to help with ext3 migration. (See also: the September 23 LWN kernel section for a discussion of ext3 and what it does).

Questions for the week: why is the traffic shaper in 2.3.x?, or even why is ifconfig still around? Both questions relate back to the same basic issue: Linux networking has a great many advanced capabilities that are, at this point, still little used. On a modern Linux system one can do things like:

  • Route different types of packets via different interfaces, even if all are going to the same destination. For example, WWW traffic can be sent via a different path than ssh traffic.

  • Put bandwidth limits on specific ports or sites.

  • Control how packets are dropped when network congestion strikes.

  • Prioritize some traffic over others.
The old 2.0 traffic shaper (described in LWN back in November, 1998) is greatly outclassed by the new quality of service code in 2.2. Similarly, the ifconfig command - a Unix classic - is left behind by the current kernel's networking capabilities. Instead, the ip command found in the "iproute2" package, can replace not only ifconfig, but arp, route, and some others as well; it is also able to control all of the newer networking capabilities of the network kernel.

The main reason for the persistence of the older networking tools appears to be documentation. Very little exists for the iproute2 and traffic control tools; thus it is hard for most people to start using them. These tools are somewhat complex and intimidating for new users.

There are documentation efforts underway, so this lack is likely to be remedied somewhat within the next few months. At that point, the traffic shaper can maybe go away, and ifconfig perhaps replaced by a shell script which translates to the new IP tools. Until then, it looks like business as usual for most users.

(The iproute2 package - and much of the fancy networking features supported by it - was written by Alexey Kuznetsov. The package may be obtained from his FTP site at ftp.inr.ac.ru/ip-routing/. A number of mirror sites exist, including ones at funet.fi and uchicago.edu. A good introduction to traffic control may be found in Werner Almesberger's Linux Expo talk, available in PostScript form from his FTP site.)

The Linux Core Kernel Commentary. "TedC" points out to us that Coriolis is about to release the Linux Core Kernel Commentary, which lists a portion of the kernel source and describes what is going on. It appears to be truly "core kernel" - things like filesystems, device drivers, networking, and more are not included.

Other patches and updates released this week include:

  • An online ext2 filesystem resizer was posted by Andreas Dilger. This tool can not only resize filesystems, but it can do it while the filesystem is mounted and in use.

  • Richard Gooch's devfs patch is up to version 127. Evidently SGI is sponsoring the devfs work at this point.

  • Modutils 2.3.6 was released by Keith Owens.

  • Trond Myklebust has ported his NFSv3 client to the 2.3 kernel series.

  • As a followup to last week's discussions on dynamic devices, Jeff Garzik posted a patch which turns the block and character device arrays into dynamic, linked lists. Some sort of change like this will be required once device numbers get bigger - the current in-kernel static arrays will simply get too large with a larger device number space.

  • H.J. Lu has released nfs-utils 0.1. This release is based on the older knfsd-1.4.7; there is a new naming and numbering scheme in effect. This release is part of the new Linux NFS Project, which has set up its own mailing list and CVS archive.

The Wonderful World of Linux 3.0 Joseph Pranevich, chronicler of new Linux features, has now sent us a grim look into post-millennial times with The Wonderful World of Linux 3.0.

Section Editor: Jon Corbet


October 21, 1999

For other kernel news, see:

 

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