2.6.25 is out

Corbet's picture

The 2.6.25 kernel has been released at last by Linus Torvalds. The plan had been to get it out a week or so ago, but a couple of stubborn problems prevented that. A marathon debugging session by Ingo Molnar turned up the last show-stopper on April 15, and the final kernel came out shortly thereafter.

When I predicted that the release would be “around tax day in the US” I came pretty close. Maybe I should do this sort of stuff for a living.

I was talking with one of the developers at the recently-held Collaboration Summit; he told me that 2.6.25 was notable in that it didn’t really have any new stuff that he was excited about. That’s pretty interesting given that this development cycle was the biggest on record: over 12,000 changesets merged from some 1200 developers and almost 370,000 lines of new code. It is true that a lot of this work was internal stuff - making things work better inside the kernel, but not visible to users. That said, there’s still some fun stuff in this release, including:

  • The “pagemap” patches. For a long time people have wondered just which processes on their system are using all the memory. The existing tools (primarily “ps”) are not as helpful as one would like for that sort of question. These patches, by Matt Mackall, enable the kernel to provide much more detailed information on memory use; this will be valuable to administrators worldwide.
  • The SMACK security module breaks the monopoly on mandatory access control previously held by SELinux. In the near future we’re likely to see more options for the hardening of Linux systems.
  • Initial support for kernel-based video modesetting. Conventional wisdom says that graphics support on Linux has been messy for a long time; now it’s getting cleaned up in a big way.
  • The Controller Area Network protocol remains interesting to me, though not because I expect to use it in the near future. CAN is a protocol for networking in noisy environments - in a car, for example. It’s how all your gadgets will talk to each other, enabling the system to, say, interrupt your phone call when the forward-looking radar has concluded that you’re about to have an unwanted encounter with the car ahead of you. This code was developed and contributed by engineers at Volkswagen - not normally considered to be a hotbed of Linux kernel hacking. The range of industries which are beginning to understand the benefits of collaborative development is impressive.
  • The ath5k driver for Atheros chipsets. This driver comes from our friends in the OpenBSD community, who made the major effort of reverse-engineering these chips. After a lengthy delay while some legal concerns were taken care of, this code has finally made its way into Linux, bringing support for one of the most problematic bits of hardware (though the 2.6.25 driver still has some rough edges). One has to wonder that the recent decision by Atheros to hire an ath5k developer and work toward mainline support for all of its hardware is purely coincidental.

That is just the beginning of the list for 2.6.25. If you want to see the whole list, head over to the always-amazing KernelNewbies changelog, which has all of the details.

So what about 2.6.26? As of this writing, the merge window has not yet opened. That can be expected to happen in the next couple of days. I think I’ll resist the temptation to predict what will go in during this cycle - I’ll get proven wrong too quickly.