See also: last week's Kernel page.

Kernel development

To add to the fun, Alan Cox has also released 2.3.99-4.2-ac1.. On the off chance that some may find this notation confusing, this patch could also be known as "Alan Cox's first patch to the second prepatch for the fourth pre-2.3.99 kernel." It contains stuff that Alan intends to eventually be integrated into the mainline kernel, including a large number of S/390 updates, a Perle Specialix RIO serial driver, an HP100 network driver update, an IBM PCMCIA token ring driver, and some sound driver tweaks.

Here is the latest 2.4 jobs list from Alan.

The current stable kernel release is still 2.2.14. Prepatch 2.2.15pre17 came out on April 2 with a claim that the real release would follow in 24 hours if no new problems came up. Said release has not yet happened, however, as of this writing.

"You agreed to the pact. Your soul is mine now." That description of devfs behavior was posted by Werner Almesberger as part of a discussion of one aspect of the devfs system: if you enable it in your kernel, your chances of having a broken system are very high unless you are running the devfs daemon as well. This happens because devfs automatically mounts itself on top of /dev, and all of the old device files that the system relies on will not be present without explicit help.

This behavior seems certain to burn a number of people once the 2.4 kernel comes out, leading to a whole rash of "2.4 is junk, my system wouldn't even boot" messages from highly annoyed users. Devfs can do cool things when properly configured, but is a trap for those who enable the kernel configuration option with the idea of trying it out "one of these days." That will probably need to change before 2.4.0 comes out. Possible solutions include not mounting devfs automatically, mounting it somewhere other than /dev, or having it automatically "see through" to the underlying directory when unknown (to devfs) devices are referenced.

New filesystem releases. The Reiserfs people are still working feverishly in an attempt to get their filesystem ready for a hoped-for inclusion in 2.4. The latest release is Reiserfs 3.6.3; it is still labelled as "beta" and does not yet fix all of the outstanding problems. In particular, testing it on big-endian systems (such as Sparcs) could be hazardous.

SGI has put out an announcement that the full XFS port is now available (and has been for a little while). XFS is said to be "still very unstable," and has only been tested on 32-bit Intel systems.

The Timpanogas group has released NWFS 2.2.2, the latest version of their NetWare filesystem implementation.

Why is there no audio CD filesystem in Linux? It seems to some that it would be a nice feature to be able to mount an audio CD and access the individual tracks as files. The problem, as it turns out, is that the process of turning the data on a CD into clean audio is far from straightforward. Audio readers must be prepared to do jitter correction and to handle failed reads due to scratches or dust on the CD. It's a task that is, at least according to some, better handled in user space.

Those who want to try an audio filesystem anyway can have a look at CDFS and AudioFS.

After the long memory overcommitting thread - some code. Eduardo Horvath has posted a patch which can completely disable memory overcommitting in the Linux kernel. Those who are truly worried about the default behavior can now experiment with a system that does not work that way. Adding some more swap space first is probably a good idea.

Other patches and updates released this week include:

• Rik van Riel has posted a new version of his fair scheduler patch.

• Bert Hubert has announced a new set of HOWTOs, covering advanced routing, traffic shaping, the logical volume manager, and 2.4 networking.

• Autodetect is a tool which seeks to ease the kernel configuration process by scanning the system to see which hardware is present and setting the appropriate configuration options.

• iptables 1.0.0, the first official release of the new firewalling and masquerading clients, has been released.

Section Editor: Jonathan Corbet

For other kernel news, see: Kernel traffic Kernel Newsflash Kernel Trap Linux 2.5.x Porting help

Other resources: Kernel Source Reference L-K mailing list FAQ Linux-MM Linux Scalability Effort Kernel Newbies Linux Device Drivers

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