See also: last week's Kernel page.

Kernel development

One thing that remains broken in this release is ramdisks. The current ramdisk implementation doesn't sit will with the new memory management in the 2.3 kernels. Until somebody fixes the problem, ramdisks will not be available.

The current stable kernel release remains 2.2.13. Work continues on 2.2.14; the latest prepatch, which is considered a release candidate, is 2.2.14pre6.

Why is the ext2 filesystem defragmenter not maintained? The answer, of course, as per this week's discussion, is that there is rarely a need to defragment ext2 filesystems. Ext2 is designed to resist fragmentation in most situations.

One exception can be with larger files. Once a file exceeds the size of an ext2 "block group," the system has no choice but to fragment it somewhat. The magic size depends on the block size used to create the filesystem. Older ext2 filesystems - of which there are a lot out there - use a 1K block size, and will fragment files that are larger than 8MB. Newer filesystems use 4K blocks instead, which can go up to 128MB.

This, of course, begs the next question: can a 1K filesystem be converted in place to 4K? The sad answer is that no such utility exists now; it is necessary to back up the filesystem, recreate it, then restore the files back onto it. For most applications it is probably not worth the effort.

Version 0.1.0-pre2 of the Encryption HOWTO is now available. This HOWTO currently covers the encryption of disks; expansion into networking (i.e. FreeS/WAN) is in the works.

BitVapor? Larry McVoy is getting closer to a release of the BitKeeper code management system, which is likely to be used for management of the kernel source in the future. In lieu of an actual release now, Larry has announced a set of screen shots which show, graphically, the history of the various kernel versions over time. Larry will also be releasing a repository containing the entire kernel development history - a lot of stuff.

Other patches and updates released this week include:

• Version 0.8 of the x86 performance counters patch was released by Mikael Pettersson.

• Matt Robinson at SGI has released version 1.0.3 of the Linux crash dump package.

• A different approach to crash dumps was posted by David Winchell. Instead of dumping to disk, this version preserves the system state in memory, and saves it on the subsequent boot. This avoids writing to disk when the system is known to be in a bad state.

• Chris Wing released a new version of his 32-bit UID patch.

• PPSkit 0.9 (nanosecond timekeeping) was released by Ulrich Windl.

• Richard Gooch's devfs patch is up to version 143. The 2.2 backport of devfs is now up to version 99.9.

Section Editor: Jon Corbet

For other kernel news, see: Kernelnotes Kernel traffic Kernel Newsflash

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