Kernel based checkpoint and restart. Oren Laadan posted version 16 of his patch series intended to add kernel based checkpointing and restart to the official Linux kernel. With the patch series applied, the kernel can save state information for running applications so that they can be later resumed from the time that they were checkpointed, or on another machine entirely.
Per-BDI writeback flusher threads. Jens Axboe posted version 8 of his patch series implementing per-BDI writeback flusher threads. This patch series was covered by the "In Brief" section of this week's Linux Weekly News Kernel Page. In the latest version, various cleanup and hang fixes have been incorporated. On a tangentially related note, Artem Bityutskiy posted a second attempt at periodic writeback timer optimization. In this patch series, the 'pdflush' kernel threads are modified such that they won't wakeup every 5 seconds as they do now, but rather will intelligently do so when data needs to be flushed out to disk or other secondary storage.
Microblaze MMU support. Michal Simek posted version two of the patchset adding support for the Microblaze MMU. For those just tuning in, Microblaze (for which support is being added in 2.6.30) is a soft synthesized core from Xilinx. John Williams, and a team of merry men, have been diligently working on support for the Microblaze for many years now. Your author can't wait to finally be able to use an upstream kernel on his Xilinx ML403 boards.
ARM device tree support. On another embedded note, support for device tree on ARM was finally posted to LKML. Janboe Ye posted a patch based on Grant Likely and Josh Boyer's original work for powerpc. This allows ARM platforms to read a flattened OpenFirmware-esque device tree blob passed in by the bootloader that describes the platform. Your author was one of those suggesting this idea back in 2005 at the Linux Symposium. Since then, many others have actually made it happen, including Grant Likely of Secret Lab, the general ringleader.
Xen. Jeremy Fitzhardinge reposted several of his recent Xen patch series for inclusion in the 2.6.31 merge window. No changes were made and apparently the patch series posted have "no outstanding issues". This is, however, unlikely to guarantee that fully Xen Dom0 support will make it into 2.6.31.
In today's announcements: Jon Masters announced release 3.9 of module-init-tools. The latest version includes a large amount of ELF cleanup work from Andreas Robinson. Karel Zak announced release 2.15.1-rc1 of util-linux-ng. This release candidate includes a number of fixes. The Linux Weekly News kernel page for May 28th is now available. It includes the new "In Brief" summary section.
Stephen Rothwell posted a linux-next tree for May 27th. Since Tuesday, a new microblaze tree was added to the compose, the linux-next tree still fails to build for powerpc allyesconfig, the vfs tree gained a conflict against the gfs2 tree, the kbuild tree lot its build failure, the v4l-dvb tree lost its build failure, the mtd tree gained a build failure to the previous day's version was used, and the rr tree gained a conflict against Linus' tree. The addition of microblaze brings the total subtree count to an impressive 141.
This final note today. Paul McKenney finally got added to the kernel MAINTAINERS file. Paul has long-since been the go to guy for RCU releated issues but wasn't listed as an official kernel maintainer until now.