• Immutable Page
  • Info
  • Attachments

KernelPodcast20090510

For Sunday, May 10th 2009, I'm Jon Masters with a summary of the weekend's LKML traffic.

In today's issue: page frame snapshots tracing, devtmpfs, a minimal linker script, and email address formats.

Page frame snapshot tracing. Ingo Molnar posted a slightly tidied up version of a patch written by Steven Rostedt aimed at adding page table dumping support to the kernel's tracing infrastructure. With this patch applied, and with the appropriate value for number of pages to dump written into an interface file provided within debugfs by the patch, subsequent page table entries will be dumped out to the trace buffer. A special binary format is used for these entries, documented within the debugfs interface itself (via one of Ingo and Steven's classical kernel-provided text files) and, additionally, within the patch. According to Ingo, the preliminary figures are "plenty fast" - 127 milliseconds to collect, 64 milliseconds to dump data on a 1GB RAM 2GHz Athlon 64, not even using splice(), yet.

Devtmpfs. Greg Kroah-Hartman posted the latest version (split into 13 individual patches) of the devtmpfs implementation. This was originally proposed by Kay Sievers on April 30th and is a special version of tmpfs created by the kernel very early in boot, before any device core device has been registered. It automatically populates the filesystem with entries for each device having a major/minor number and is intended to complement udev by providing a few prepopulated devices that are initialized even before udev has been started. This saves udev from performing a coldplug uevent replay operation the moment it starts, which in turn shaves a few seconds from a typical system boot time. Embedded systems save a need even to include something like udev. Yes, everyone and his dog have made jokes and jibes about devfs.

A minimal linker script. Sam Ravnborg, kbuild infrastructure maintainer, has posted what he describes as a "minimal linker script" that follows his grand plan for cleanups to the tree. He has asked for feedback.

The weekend's bikeshed painting exercise came in the form of a discussion around email address formats recommended for the kernel MAINTAINERS file. In a followup, Andrew Morton affirmed that a format including both name and current email address would be useful for cut-and-pasting into logs.

In today's announcements: qgit version 2.3.

The latest kernel release is 2.6.30-rc5, which was released by Linus on Friday evening. Since then, Greg Kroah-Hartman has posted some updates to the driver "staging" tree, which include some new device IDs and a couple of bugfixes. Linus was additionally sent requests to pull from GFS2, the net tree, and the sound tree. All of these contain fixes intended for 2.6.30.

That's a summary of today's LKML traffic. For further information visit www.kernel.org. I'm Jon Masters.

Tell others about this page:

last edited 2009-05-11 17:00:31 by JonMasters