LKML Summary Podcast

Audio: http://traffic.libsyn.com/jcm/linux_kernel_podcast_20110328.mp3

For the weekend of March 27th 2011, I’m Jon Masters with a summary of this week’s LKML traffic. Yup, it’s back, sorry it was away so long.

In this week’s issue: SMBIOS, Lazy patch checking, and farewell to APM.

SMBIOS vs. DMI. SMBIOS has long since replaced the DMI specification (the last update to DMI was apparently in 2003), but the kernel is still DMI-centric, having been overloaded to understand various parts of SMBIOS. This is a trend that has been going on for some time, but it finally annoyed Prarit Bhargava enough to want to do something about it – he proposes various changes to expose SMBIOS data directly in sysfs in a thread entitled “SMBIOS: Add initial code and export version via sysfs”. Alan Cox was keen to retain backward compatibility and preserve the same userspace API, even if the actual data being provided came from SMBIOS rather than legacy DMI. (disclaimer: I discussed this with Prarit as part of a separate issue).

Lazy Patch checking. Sarah Sharp hit upon a common problem when cleaning up existing code. Checkpatch would report an error on lines exceeding 81 characters in length, even though she didn’t write the original code. To make such review and improvement work less cumbersome, Sarah adds a “–lazy” flag to checkpatch.pl to change the return code on such errors. She notes she’s “not a perl hacker”, which is of course not a failing.

Farewll APM. Len Brown posted a feature-removal-schedule update that will plan the removal of “APM” power management in 2.6.40. It’s been a long time since ACPI and its kin killed off the need for APM on modern systems. Apparently, Microsoft pulled this support in 2006, so 5 years later is probably more than sufficient for Linux systems(!).

In this week’s pull requests for the 2.6.39 merge window:

* Stefan Richter requested Linus pull some firewire updates, including an ALSA bug fix.

* Jean Delvare requested Linus pull some hwmon subsystem updates, including support for two new devices (ADS1015, and SMSC SCH5627).

* Alex Elder requested Linus pull some XFS updates.

* Michal Marek requested Linus pull some kbuild updates (v2).

* Ingo Molnar requested Linus pull some x86 fixes.

* Miklos Szeredi reqested Linus pull some fuse updates.

* Pekka Enberg requested Linus pull some SLAB changes that include SLUB lockless fastpath patches from Christoph Lameter.

* Sage Weil requested Linus pull some Ceph and RBD updates, including “support for an object watch/notify framework that allows and RBD block device to get/send notifications about snapshot creation”.

* Dave Airlie requested Linus pull some drm fixes, including “One radeon, 2 core fixes, and an interface update to allow for 2 > crtcs in vblank”.

* Takashi Iwai requested Linus pull some sound fixes for VIA HD audio codes, and “a few other small fixes”.

* Samuel Ortiz requested Linus pull some MFD fixes, including MFD cell sharing support, and new drivers for TI’s TPS6105x, Maxim MAX8997, STE AB8500 GPADC, and Intel’s Tunnel Creek).

* Roland Dreier requested Linus pull some infiniband fixes.

* J. Bruce Fields posted some nfsd changes, including a new interface from Kevin Coffman to allow userspace to query for enctype support.

* Al Viro posted some vfs and procfs fixes, including fixes for “dumb leaks in path_lookupat() and a large pile of procfs fixes”.

* Phillip Lougher requested Linus pull some squashfs updates, including support for reading compression options out of the filesystem.

* Florian Tobia Schandinat posted some viafs cleanup patches.

* Colin Cross posted some ARM Tegra updates.

* Len Brown requested Linus pull some ACPI patches, and some idle patches.

* Mike Frysinger requested Linus pull some changes for blackfin.

* Mauro Carvalho Chehab requested Linux pull some drivers/media updates, which includes the addition of the “Media Controller API”, required to “adjust stream parameters on SoC media devices”.

* Alasdair Kergon requested Linus pull some device-mapper patches.

* Artem Bityutskiy stated he had found “a couple of brown-paperbag bugs”, so posted a second UBI/UBIFS pull request to take care of the matter.

* Anton Vorontsov requested Linus pull some battery fixes.

* Ted Ts’o requested Linus pull some ext4 updates.

* Trond Myklebust requested Linus pull some NFS client changesets.

* Martin Scheidefsky requested Linus pull some s390 patches.

* Ingo Molnar requested Linus pull some core kernel, IRQ, perf, and x86 fixes.

* Thomas Glexiner requested Linus pull some additional IRQ cleanups. These included code for architectures which Ingo considers “orphaned”, but Ingo had done some cross-building at least to check they still build.

* Jesse Barnes requested Linus pull some PCI fixes.

* James Bottomley requested Linus pull some “final SCSI updates”.

In this week’s miscellaneous items:

* Amerigo Wang posted a patch implementing “acpi_addr” kernel command line handling for passing the ACPI RSDP structure (pointer) into kdump kernels. Cong Wang suggested that this be renamed acpi_rsdp instead.

* Shawn Guo posted some patches to SDHI support to take driver specific bits out of sdhi-pltfm.c and “make them self registered”.

* Joseph Cihula posted a patch disabling Intel VT-d Protected Memory Regions (PMRs) when the kernel has been launched with TXT (trusted execution).

* Tony Luck posted a patch removing normal shutdown logs from the new “persistent store” (pstore), to avoid cluttering up limited storage. Seiji Aguchi considered it useful to retain normal shutdown logs for Enterprise use. Artem Bityutskiy and Americo Wang considered this policy in kernel and offered a mount option as the preferred solution to deciding logging action.

* Sarah Sharp noticed that PCI hotplug wasn’t working properly on 2.6.38 for her particular setup. Rafael J. Wysocki pointed out a stable-bound patch, which Sarah tested and soon found PCI hotplug working again.

* Dave Chinner posted some “vfs: inode lock breakup” patches, which are “derived from Nick Piggin’s vfs-scale tree”. He has been “sitting on them until the dache_lock breakup and rcu path-walk has had some time to be shaken out”. He forward ported the patches and ran some XFS/ext4 tests.

* Paul Turner posted version 5 of his CFS Bandwith Control patch series.

* Herbert Poetzl inquired about “debugging a modern laptop …”, which Andi Kleen replied to. In his reply, Andi pointed out the existance of the USB DebugPort, which is an optional feature built-in to many EHCI controllers. There’s usually only one, and it requires a $100 cable, but this is something this author has not played with and suspects many others haven’t either. An investment of $100 isn’t bad if you need to routinely debug laptop kernels. Mark Lord added that those with ExpressCard slots could pick up an “Oxford Chipset” card, which provides true serial/parallel ports, the latter of which can also be used for homebrew JTAG adapters (according to Mark).

* Kamezawa Hiroyuki posted an RFC patch entitled “A forkbomb killer and mm tracking system”, which is all new compared with older posts, and apparently includes support for dead process tracking (struct mm_struct tracking).

* Tejun Heo was cleaning up the custom locking in btrfs, migrating to standard kernel mutex adaptive spinlocks. He noted that mutex_trylock doesn’t currently do adaptive spinning, but that it probably should in his benchmarks (and that btrfs equivalent code was already doing this). Linus thought this sounded reasonable, and Tejun updated his patches accordingly.

* The Microsoft HyperV folks posted a few staging cleanups.

* Thomas Gleixner posted some final ARM genirq cleanups.

* David Miller posted some Networking, and SPARC cleanups.

* Rafael J. Wysocki requested Linus pull some more power management updates.

* Jonathan Corbet posted some documentation updates.

* Jens Axboe requested Linus pull some block driver updates.

* Tony Lindgren requested Linus pull some OMAP fixes.

* Guenter Roeck requested Linus pull some hwmon fixes.

* Liam Girdwood requested Linus pull some voltage regulator updates.

In today’s announcements:

* Christian Dietrich announced “undertaker” version 1.1. This is another static code analysis tool for C code that users preprocessor directives. It’s part of work done by the VAMOS team at the University of Erlangen.

* Scott James Remnant announced the release of version 1.2 of “Upstart”, the premier legacy init replacement daemon for Linux systems. In this release, Scott corrects a “brown paper bag” bug that broke use of pdksh.

* John Linn requested that Stephen Rothwell include the new Xilinx ARM tree in linux-next.

* Junio C. Hamano announced the releast of Git 1.7.4.2. It includes lots of fixes, even half hour GMT timezone offset support in gitweb.

The latest kernel release is 2.6.38.

Greg Kroah-Hartman announced the release of stable kernel 2.6.33.8, which is intended for use by the pre-empt RT kernel patch, which is still 2.6.33 based.

Greg Kroah-Hartman announced the release of stable kernels 2.6.32.34, 2.6.38.1, and 2.6.37.5. Later, Greg posted 2.6.32.35, which had only a build fix for those bitten with a particular build problem on 2.6.32.34.

Tony Luck requested Linus pull some IA64 changes.

Greg Kroah-Hartman requested Linus pull some USB changes for problems reported so far during the 2.6.39 merge window.

Paul Mundt requested Linus pull part two of super-H updates and some rmobile updates.

John Linville posted some further wireless fixes for 2.6.39 to Dave Miller.

David Howells requested Linus pull some NOMMU and FRV patches.

Con Kolivas announced the release of 2.6.38-ck1, which includes various patches of his intended to “improve system responsiveness”.

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

Finally this week, Lukasz Sokol noted that the UK branch of WalMart is selling a very tux-like product, wondering if this was a legal issue. Alan Cox responded that Larry Ewing was “sort of CC-BY”, requiring attribution if asked, so that was probably ok. But more worrying to Alan was “the unfortunate placing of the stick which means it looks like its taking a crap”.