LKML Summary Podcast

Audio: http://media.libsyn.com/media/jcm/linux_kernel_podcast_20091209.mp3

For Wednesday, December 9th 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: Audio, hardware breakpoints, kbuild, and tracing.

Audio. Mark Brown, Linus Torvalds, Alan Stern, and others had a conversation concerning audio chipsets requiring reference voltages in which the hardware isn’t wired with a convenient reference to use and so various ramping up and down is required at suspend and resume time. Apparently, a delay is necessary in order to avoid a loud noise coming from the sound device on such hardware.

Hardware Breakpoints. Frederic Weisbecker noted a design flaw with the existing hardware breakpoint code. It turns out that the current design, which allows one to modify an existing breakpoint entry, does so by first unregistering and then re-registering the modified form thereof. This is racy with respect to another task creating a similar breakpoint. Frederic’s fix is to instead mark a breakpoint disabled during modification, then re-enable it.

Kbuild. Nir Tzachar pointed out some issues with the new ncurses based menu system that is being worked on. Specifically that lxdialog/check-lxdialog.sh always includes the “wide” (ncursesw) version of the library even if only the “narrow” version is needed, as in the case with the kernel. This can result (on systems with both versions installed) in non-color menus. Nir’s fix is essentially to ignore the “wide” version since it is not being used.

Tracing. Tim Bird posted a variant of the ftrace function tracer (build upon it) that can be used to filter on function duration, especially useful for embedded devices that wish to measure function duration during boot.

In today’s announcements: util-linux-ng version 2.17-rc2. Karel Zak announced the second RC of the forthcoming 2.17 release of util-linux-ng. As Karel previously mentioned, this version introduces a number of overhauls.

The latest kernel release is 2.6.32.

Americo Wang noted a regression in the current git tree, in the VM. He can’t reproduce it at the moment but it triggers in swap_free. Hugh Dickens said it looked like something had corrupted the start of a page table.

Stephen Rothwell posted a linux-next tree for December 9th. Since Tuesday, the omap tree lost its conflict, the samsung tree no longer needed a fixup and lost all its conflicts, the powerpc tree gained a conflict against Linus’ tree, the ext3 tree lost its conflict, the kbuild tree inherited a merge fixup from the net tree, the kvm tree lost its conflicts, the net tree lost its merge fixups, the kgdb tree lost its conflict, the slab tree lost its build failure, the omap_dss2 tree gained a conflict against the omap tree, the tip tree gained a conflict against Linus’ tree, the percpu tree lost 2 conflicts and its merge fixup (due to changes in the kgdb and tip trees), the hwpoison tree lost its build failure, the sysctl tree lost its conflicts, the tty tree gained a conflict against the trivial tree, the usb tree gained a build failure for which Stephen revered a commit, and the staging tree gained a conflict against Linus’ tree. The total sub-tree count remained steady at 155 trees in the latest compose and Stephen repeated his usual “call for calm” that people not merge items intended for 2.6.34 until after 2.6.33-rc1.

Finally today, Johannes Stezen asked Linus why the kernel name was no longer being updated post-2.6.32. Linus eventually replied (a day later, but since this update is late anyway, I’ll add it now) saying that he updates the name totally randomly, usually after he reads something that strikes him as funny.

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