Kernel Log: Linux 2.6.30 is taking shape

The release of 2.6.30-rc1 marks the end of the development phase for integrating the majority of the changes scheduled for 2.6.30.

Kernel Log logo Between Tuesday and Wednesday, Linus Torvalds released Linux 2.6.30-rc1, the first release candidate of version 2.6.30 of the Linux kernel. The final version is expected in eight to ten weeks. Fifteen days after the release of Linux 2.6.29, the first RC of 2.6.30 closes the merge window, the first phase of the development cycle in which the kernel hackers integrate all the major changes into the main development branch; the coming few weeks will be dedicated to eliminating any flaws the testers find in the release candidates.

Statistically, the programmers modified 8344 source code files; 980,137 lines were added or moved, and 372,613 lines were deleted. In his release email, Linus Torvalds points out that a third of the changes are "crap", as they affect the staging area, which is primarily intended for immature drivers and isn't popular with everyone. He said a further third of the changes are "real" drivers, and the final third affects other kernel areas.

What's (not) new

After two new file systems, Btrfs and SquashFS, already made it into the main development branch with Linux 2.6.29, version 2.6.30 will include a further two new file systems: NILFS2 (New Implementation of a Log-structured File System version 2) and exofs (Extended Object File System; previously known as osdfs). NILFS2 is a log-structured file system (LFS) that offers "continuous snapshotting", a technology specially optimised for Solid State Drives (SSD) without wear levelling; exofs, on the other hand, is intended for the somewhat exotic OSDs (Object-Based Storage Devices) (see also: kernel documentation for NILFS2 and exofs). Desktop users are, therefore, unlikely to have much contact with either of these file systems.

In addition to the new file systems, the kernel hackers have integrated the TOMOYO security framework, version 1.0.19 of the ALSA audio drivers, and numerous new WiFi drivers; also, the WLAN stack is to offer better support for the power saving functionality of modern WiFi hardware. As planned, a number of additional fastboot patches that allow the kernel to initialise several of its subsystems at once promise to speed up system booting.

The Direct Rendering Manager (DRM) of Linux 2.6.30 will offer rudimentary support for the R6xx and R7xx GPUs used in the series 2000, 3000 and 4000 Radeon models. Together with suitable X.org graphics drivers, this enables 2D and video acceleration; access to these GPUs' 3D units is still in development. The KVM code now offers nested virtualisation for AMD processors – this allows for guest operating systems to host their own guest systems.

Over the next few weeks, the Kernel Log will discuss the details of these and many further new features in its "What's new in 2.6.30" mini series – as Linus Torvalds usually still merges one or two substantial changes that missed the merge window in the days after the release of the first RC, we'll delay the start of the mini series for another few days.

The code for Xen Dom0 operation hasn't made it into the main development branch so far; while it could be among the possible late-comers, this seems rather unlikely. Another feature that hasn't made it into 2.6.30 is Ext4 online defragmentation.

In Brief

The squashfs-developers released matching userspace tools for the SquashFS-Code from Linux 2.6.29.

As previously reported, the maintainer of Linux stable series kernel version 2.6.29.1 released nearly 50 bug fixes and minor enhancements ten days after the previously published version of Linux 2.6.29.

In future Luis R. Rodriguez wants to offer the wireless subsystem and the driver contained in the current Linux kernel as backports. That should mean that older versions, from and including Linux version 2.6.27, will be able to support the newer WiFi drivers.

The X.org developers have released the 2.1.13 version of the video driver xf86-video-nv for Nvidia cards. However, in the past few months, the driver has not seen much improvement. Support for newer GeForce graphics hardware is only minimally expanded, and the XVideo support for the G90 and newer GPUs is still lacking.

In June of this year, the Linux Wireless developers will hold a mini-summit in conjunction with FUDCon LinuxTag Berlin 2009.

SGI has released as open source a number of programs, previously used internally to test file systems.

Linux WiFi Developer Johannes Berg has been working on a revision of the already substantially revised rfkill kernel framework that controls the interaction between hardware, kernel and user space programs when pressing buttons and hotkeys on notebooks that turn radio links on and off.

The kernel developers will begin making concrete plans for this years Kernel Summit, taking place in Tokyo, Japan from the 18th to the 20th of October.

At the end of last month, AMD released version 9.3 of the Linux Catalyst graphics drivers otherwise known as proprietary fglrx. The release notes provide an overview of the innovations of the latest version with support for the Radeon X1950 models 9500 and notes on set up for the R300, R400 and R500 series GPUs.

Luis R. Rodriguez has created a new wiki page which indexes the different Kernel.org-based wikis.

Last Autumn's decision that pressing the key combination CTRL + ALT + Backspace would no longer terminate X Server (DontZap) has been the subject of discussion on the mailing list xorg-devel and fedora-devel over the past two weeks.

Further background and information about developments in the Linux kernel and its environment can also be found in previous issues of the kernel log at The H Open Source: