21 April 2008, 08:49

Improvements throughout

Thorsten Leemhuis

What's new in Linux 2.6.25

Linux 2.6.25 packs new and improved Wi-Fi drivers, improvements to Ext4 and Completely Fair Scheduler (CFS), the new Smack security framework, and numerous improvements in both hardware support and infrastructure. But the new kernel toes a hard line when it comes to proprietary USB drivers.

With well over twelve thousand – and rising – commits between Linux versions 2.6.24 and 2.6.25, kernel developers have never been as productive in the 2.6 series as they have been in the past weeks. Taken together, the changes amount to more than a million of the nearly nine million lines in the Linux kernel's source code archive, adding numerous important updates that all Linux users will profit from sooner or later.

The kernel hackers further improved Wi-Fi support – already reworked in 2.6.24 – integrating a number of additional drivers for various Wi-Fi hardware into the kernel. Once again, there are also several real-time environment improvements, among them the still maturing Completely Fair Scheduler (CFS) that juggles programs and their threads. The development of the Ext4 file system, integrated into the kernel a few months ago for testing and development purposes, has also come quite a long way. The Smack security framework, supposedly easier to work with than SELinux, is included for the first time. Some of the updates in 2.6.25 may seem like a step backward to some users. The new Linux version denies proprietary kernel module USB drivers access to some central and functionally essential driver interfaces.

The changes mentioned are only the most important ones in Linux 2.6.25, which, like every other new kernel in the main development line, also contains scads of new and updated drivers along with numerous improvements to the infrastructure. The changelog lists in detail all of the adjustments since 2.6.24 for anyone that wants to know exactly what was changed and has the time to study the several megabyte-long document. A brief overview of the improvements already mentioned and many other important updates can be found in the following sections of this feature: