Linux in the news
All in one big page
See also: last week's Kernel page.
The current development kernel release is 2.4.0-test4. See the diffstat listing for the full list of changed files; in summary, the patch includes the addition of support for Orion boards as another MIPS sub-architecture, a big update to the Microgate SyncLink ISA and PCI serial adapter driver, more ACPI code work, some PowerPC tweaks, a sizeable update to the memory technology device driver, and a number of other small tweaks.
There are already three 2.4.0-test5 prepatches out there, with the latest version being 712K in size. The majority of that patch seems to be codepage updates, though a large update to the bttv driver also accounts for some of it.
The current stable kernel release is 2.2.16. The 2.2.17 prepatch is up to 2.2.17pre13, released without announcement on July 16th. Here is Alan's announcement for 2.2.17pre12, which came out just a couple of days before that. Comparing the two, pre13 appears to mostly hold S390 changes.
Meanwhile, for those still working in the older world, David Weinehall has released the sixth prepatch to the 2.0.39 stable kernel release.
The Wonderful World of Linux 2.4. Joe Pranevich has put out the "final draft" version of his Wonderful World of Linux 2.4 document, which describes the changes to be found in the upcoming 2.4 kernel. Check it out for a comprehensive discussion of what's coming.
RTAI releases real-time Linux add-on for kernel 2.4.xx (LinuxDevices). RTAI, the "Real Time Application Interface", is a real-time extension for Linux. It is also now available for the 2.4 kernel series. "Paolo Mantegazza, RTAI project leader, says the new release 'is a relatively advanced porting of RTAI to the approaching Linux [kernel] 2.4.xx, both for [Intel-x86] and PowerPC architectures'. The current RTAI version supports kernel 2.3.99-pre6 and 2.4.0-test1".
API changes, 2.4, and the release cycle. It all started with this message from Alexander Viro, describing a change in the way a number of functions in the kernel are called. A number of methods that used to be called with the "big kernel lock" held, such as revalidate, readlink, follow_link, open, and release, will now be called without that lock. If they need the big kernel lock, it will be their responsibility to obtain it themselves.
The big kernel lock is a historical remnant from the early days of Linux symmetric multiprocessing (SMP). Back in 2.0, this lock was used to insure that only one processor was running kernel code at any given time. Organizing things that way made SMP easier to implement, but leads to contention problems even with two processors. Thus, later versions of the kernel have been slowly eliminating the big kernel lock in favor of more fine-grained schemes. The change under discussion here is another step in that direction.
The problem, of course, is that the kernel developers are supposed to be stabilizing things in hope of actually getting 2.4.0 out someday. Thus Alan Cox, among other developers, has asked that Linus refuse these changes in the interest of kernel stability. Linus has, however, listed his reasons for accepting the patch, and it is going in.
Hans Reiser, not one to miss an opportunity, has pointed out that adding ReiserFS is not a very big change compared to some others that are still going in.
The kernel developers will cope with this change, of course, and 2.4.0 will come out at some point. But the explicit goal of a shorter development cycle for 2.4 is clearly not coming to be. Linus seems to have a hard time making feature freezes stick; as he puts it himself, he's "a push-over and a wimp." So the new stuff keeps going in. There is little doubt that 2.4 will be a better kernel for all of the additional work, but it's also a much later kernel.
Some ideas have gone around on how to avoid these delays the next time. They include:
Then, there is the simple idea of imposing feature freezes earlier, and, importantly, sticking to them. Linus has made it clear that he means business with the 2.4 freeze at this point:
I want you guys to look at your computer screen, imagining the worst monster you can (the cacodeamon from Quake will do, just make him hairier and bigger and more MEAN), and think of me. Think of me like I am when I see a patch which isn't a pure bug-fix.
Alan Cox then took the opportunity to point out that Linus needs to grow a beard if he's going to pull off the "hairier" part...
Other patches and updates released this week include:
Section Editor: Jonathan Corbet
July 20, 2000