LKML Summary Podcast

Audio: http://media.libsyn.com/media/jcm/linux_kernel_podcast_20091123.mp3

For Monday, Novemember 23rd, 2009 , I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: Ftrace for Microblaze, kexec, kprobes, KVM, LIRC, and rwlocks.

Ftrace for Microblaze. Michal Simek posted a five part patch series implementing ftrace support for Xilinx Microblaze soft-core CPUs. On a tangent, your author is interested in reviving his ML403 board and running the latest Microblaze – anyone wanting to help out can drop me a line.

Kexec. Amerigo Wang reposted a patch series intended to provide support for reducing the reserved memory used for a crash kernel if it is already more than sufficient to store the crash kernel image. The patch implements a new sysfs interface through which one can reduce the reservation size.

Kprobes. Masami Hiramatsu posted version 5 of a 10 part patch series implementing optimized jumps (aka “Djprobe”) for probe points. Kprobes is the dynamic probe infrastructure intended to allow one to insert probe functions at certain points within the kernel. Jason Baron and others have also recently been working on jump optimization with labels, and so might benefit from working with Masami on a common approach to such patching.

KVM. Gleb Natapov posted the second version of a 12 part patch series implementing asynchronous page fault support for paravirtualized KVM guests. With appropriate support in the guest kernel, and the right communication between it and the host KVM hypervisor, the guest kernel can receive a hint that the page it needs is currently not available and will be faulted in, allowing it to switch to another task in the interim.

LIRC. Mauro Carvalho Chehab, and Jarod Wilson debated the future of the until now out-of-tree LIRC Infra-Red drivers vs. implementing such support through the standard kernel input layer. Doing IR through the standard input interface would mean that the kernel could handle a lot of the heavy lifting, but it would be based upon an assumption that the majority of IR users are really controlling input devices over that protocol, and not weird IR gadgets.

RW Locks. Nick Piggin raised the issue of fairness for rwlocks. The current implementation of rwlocks in the Linux kernel is (intentionally) unfair with respect to writers, which can be starved for some arbitrary period of time. As Nick points out, there are few users of rwlocks in the current kernel, but he would nonetheless like to have a “fair” alternative.

Finally today, Luis R. Rodriguez asked about bug reporting for open firmware (not the OpenFirmware system level firmware, but other firmware for which the source is open), now that there is at least one (ar9170) device firmware for which source is available. He wonders whether it makes sense to discuss on LKML or whether there is a more appropriate answer.

The latest kernel release is 2.6.32-rc8.

Stephen Rothwell posted a linux-next tree for November 23rd. Since Friday, the omap, infiniband, input, alacrity, and staging trees lost conflicts, while the microblaze, mips, net, mfd, and tip trees had issues. The total subtree count remains steady at 151 trees.

That’s a summary of today’s Linux Kernel Mailing List traffic, for further information visit www.kernel.org. I’m Jon Masters.