See also: last week's Kernel page.

Kernel development

Alan Cox has also put out 2.3.3ac3 with a separate set of small changes. Alan had originally said that the "ac" patches were going to go away now that 2.3 is active, but that does not appear to have happened yet.

The current stable release remains 2.2.9. There are a few reports of glitches with this version, but as a whole it has held up better than some of its predecessors.

Kernel hacker Theodore Ts'o is going to VA Linux Systems in June, as announced at Linux Expo last week. He will be working full time on file systems and other goodies for Linux.

SGI will be releasing their XFS file system for Linux under some (unspecified) open source license. See their press release for the details and hype. XFS promises to bring to Linux all kinds of "enterprise" capabilities that people have been asking for: high performance, large file support, journaling, etc. If all goes as expected, Linux will have acquired something good. Thanks are due to SGI for this gift.

Meanwhile, of course, work is proceeding on adding various capabilities to the ext2 file system: higher performance, large support, journaling, etc. Now that XFS is being dropped on our doorstep, does it make sense to go forward with this work? This question was asked on the kernel list this week, and was answered with a resounding "yes." Ext2 work should proceed, for a number of reasons.

For example, SGI has not yet said what license they will apply to the software. If the license does not play well with the GPL, XFS can not be part of the standard kernel. SGI still needs to pass through the code looking for patent and license problems; there is also the little detail of actually porting it to Linux. So it will be a while before we see any code. And if XFS requires substantial changes in other parts of the kernel, those changes have to be done to Linus's satisfaction.

Thus it has been predicted that a functioning, stable XFS in Linux is at least a year away. The ext2 work will be able to address needs far sooner than that. Ext2 remains, and is likely to remain the standard Linux file system (OK, it will probably be "ext3" when all the changes go in), and certainly development will proceed.

How to name USB devices? Development on the Universal Serial Bus drivers is reaching the point where developers are worrying about problems like: what name should a device on the bus have? USB devices are essentially anonymous things: they can come and go, and they can appear at different places in the bus topology at different times. So how do you manage to give the devices consistent names for the user?

A number of ideas were passed around, including somehow using devfs for this task. But Linus shut down the conversation by saying that the problem is essentially unsolvable and that there is no point in even trying. USB devices should just be assigned whatever name is first available when they are scanned by the kernel. It is not possible to do better than that, so there is no point in really trying.

For some sorts of devices, such as mice, Linus's preferred approach is to simply have a single logical device, even in situations where there are multiple physical devices. That, he hopes, will correspond best to what the user wants. For other devices (diskettes, printers, etc.) names are just assigned as the devices are seen. He states that the comings and goings of USB devices should be treated more like media changes than device configuration events.

There is not a consensus on this issue at this point, and there is talk of trying to somehow create consistent naming at the user level. In any case, the USB stuff is very young, so a lot of evolution is yet to happen.

Here's a useful resource: Linux 2.2 (mostly networking) is a web page dedicated to information about the 2.2 networking features. If you are looking for information on any of the many networking goodies included with 2.2, this page is a good place to start.

Other patches and releases of interest:

• Richard Gooch has released devfs v103.

• H.J. Lu has released knfsd 1.3.2.

• /dev/changer is a driver for CD changers which makes all of the discs in the device available in a virtual mode.

Section Editor: Jon Corbet

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