Linux in the news
All in one big page
See also: last week's Kernel page.
The current development kernel release is still 2.3.99-pre6; there has not been a mainstream kernel release since April 26. In the "testing" area, however, things have been active - the preprepatch for 2.3.99-pre7 is in its ninth revision as of this writing. It contains the new configuration option controlling whether devfs is automatically mounted at boot time, the new devfs FAQ, a whole new PowerPC 8620 ethernet/serial driver contributed by MontaVista Software, a number of ethernet driver, USB, and PCMCIA updates, a new Specialix RIO driver, and a new "PPP over ethernet" driver. This prepatch also contains a significant rewrite of the mount/superblock handling code; things are not stabilizing quite yet.
The recent development kernels still appear to have severe memory management problems - at least for some users. Reports of the kswapd thread using 70% or more of the CPU are common. There is increasing interest in simply backing out a number of the recent memory management changes in the hope that things work better again for the short term. Meanwhile a number of hackers are working toward better memory management in the future. In particular, Andrea Arcangeli's classzone patch has gotten a number of good reviews.
(Andrea, by the way, will be speaking at the May 16 Bay Area LUG meeting in San Francisco).
The current stable kernel release is 2.2.15, released on May 7. Alan Cox has moved forward with 2.2.16pre2, which contains quite a few fixes and updates already. Andrea Arcangeli, meanwhile, has released 2.2.15aa1, which enhances the 2.2.15 kernel with quite a few goodies, much of which (big memory, large file support, raw I/O) is backported from the 2.3 series.
What's in your kernel? The Linux kernel is said to be the grand unifying factor which keeps all Linux distributions at least somewhat the same. But, as it turns out, the distributors do not ship kernels direct from Linus - each applies its own patches and tweaks. Last week we looked at the Linux-Mandrake 7.0 kernel; this week instead we grabbed the kernel source package for Caldera's eDesktop 2.4. Here's what we found:
Caldera's kernel is thus relatively lightly patched. The one thing there that's perhaps unique is the streams patch, for which most Linux distributions (and users) have little use.
Should USB require devfs? Universal Serial Bus devices are by their nature dynamic - they come and go whenever the user inserts or removes a plug. The USB development team has implemented the USB device filesystem (or "usbdevfs") as a way of keeping up with what the user is doing. Usbdevfs is a dynamic filesystem which tracks the state of the USB; as devices are added, a corresponding entry shows up in usbdevfs (customarily mounted on /proc/bus/usb).
Some readers may have noticed that usbdevfs sounds much like devfs, which is now part of the 2.3 development tree. The USB folks noticed that too, and have been merging usbdevfs into devfs with the goal of having just one dynamic device filesystem. It's an idea that would seem to make some sense.
Except that not everybody is thrilled with the idea of needing devfs to be able to use USB devices. Devfs remains controversial at best. But, more importantly, it is not at all clear when the distributions will start shipping kernels with devfs enabled. Even when they go with the 2.4 kernels, distributors may shy away from devfs for a while. Running devfs requires that a system be reconfigured in a non-trivial way; distributors will hesitate before requiring that of their users.
The merge of usbdevfs and devfs will probably continue. But there's also likely to be some sort of short-term hack that will allow systems to function with USB in the absence of devfs. The final destination seems to be clear, but not everybody wants to get there at the same speed.
Meanwhile, the latest USB 2.3.99 jobs list has been posted by Randy Dunlap.
Other patches and updates released this week include:
Section Editor: Jonathan Corbet
May 11, 2000