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Skip-free audio and video playback is a fundamental expectation for many - if not most - Linux users. Given the importance of this feature and the increase in hardware performance over the years, one would think that the audio latency problem would have been solved some time ago. The recent posting of (and mixed reception for) the "RealtimeKit" mechanism shows that this issue remains open, though, and that we are still short of a consensus on how it should be solved. Click below (subscribers only) for LWN's report.

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Back in May, the proposed "no long file names" patch got a hostile reception on the linux-kernel mailing list. This patch, presumably aimed at working around Microsoft's VFAT patents, made the kernel unable to create long file names on VFAT filesystems. It was seen by many as a reduction in functionality without any sort of well-explained justification, and it was not merged. Now there is a new patch which takes a different approach on both the technical and political fronts. Its fate remains to be seen, but it demonstrates a method for dealing with patents which is worthy of wider consideration. A look at the new patch and patent avoidance strategies in general, can be found below (subscribers only).

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The slow loris is an exotic animal of southeast Asia that is best known for its slow, deliberate movements. This characterizes the technique used by a new Denial of Service tool that has been named after the animal. Slowloris was released to the public by security researcher "RSnake" on June 17. Guest author Christian Folini takes a look at slowloris on this week's Security page (subscribers only).

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Guest author Neil Brown wraps up his series on kernel design patterns with a look at "midlayers". These layers sit between a layer that implements a wide range of services (such as POSIX system calls), and a layer that is specific to a piece of hardware or filesystem. While it is tempting to implement midlayers as an actual layer that requires all requests to pass through them, that is the essence of the "midlayer mistake" pattern. Subscribers can read more about this pattern in the article from this week's Kernel page.

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Guest author Valerie Aurora is frequently asked about chunkfs, which is a prototype file system implementing "repair-driven" file system features. Her answer: "Chunkfs works, the overhead is reasonable, and it is only practical if it is part of the file system design from the beginning, not tacked on after the fact. I just need to write up the paper summarizing all the data." That paper is now available, subscribers only, from this week's Kernel page.

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FreedomHEC (Freedom Hardware Engineer's Conference) Taipei was held June 10 and 11 in, unsurprisingly, Taipei, Taiwan. The event, sponsored by the governmental Institute for Information Industry, followed the huge Computex conference in the hope of attracting hardware developers who are interested in supporting Linux. LWN Executive Editor Jonathan Corbet spoke at FreedomHEC; the following report (subscribers only) gives a look at the conference and what it accomplished.

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In part two of this three-part series, guest author Neil Brown looks at the patterns embodied in kernel data structures. In particular, he examines lists, red-black trees, and radix trees to find common patterns in the kernel implementations. Because performance is such an overriding concern for kernel hackers, the data structure implementations are rather different than the "Abstract Data Types" that are normally considered—at least academically—the proper way to handle such things. Click below, subscribers only, for the second installment from next week's Kernel page.

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The idea of "design patterns" came from the field of Architecture, but have been used for software development, particularly object-oriented programming, for many years as well. When the visibility of these patterns is raised, so that more developers know and understand them, better quality code can result. In the first part of a three-part series, guest author Neil Brown looks at design patterns in the Linux kernel and how they can lead to improved quality of kernel code.

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Your editor once thought that the Xen Dom0 patches might be merged for 2.6.30. So much for editorial infallibility. The Xen Dom0 discussion has restarted; based on that, your editor will be making no such predictions for 2.6.31. Click below for the full report from this week's Kernel Page.

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One of the biggest advantages of free software is that it is usually written with the needs of its users in mind. Proprietary software, instead, has more of a tendency to reflect the interests of its owners. Thus, free applications do not normally implement "features" which allow their users to do less. One might think that the consensus against "antifeatures" in free software is nearly universal, but, as the case of the okular PDF reader in Debian shows, there are still exceptions.

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Current news

Michael Tiemann reports on his recent trip to Brazil for FISL 10. He notes that free software adoption is growing rapidly within the Brazilian government. He also describes an effort by the Malaysian government to reward use of free software, rather than the development of it, because that can lead to multiple, competing solutions that don't necessarily solve the users' problems. In addition, he also noted a barrier to free software adoption: "On the alarm front, I heard specific confirmation of a storyline I've been following, which is that the Bill and Melinda Gates Foundation is basically telling governments: if you want contributions/investments from us, then you'll give Microsoft cabinet-level access to inform policy, and you'll use Microsoft products. For example, donations to educational initiatives require installing and teaching Microsoft products."

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Linux Journal takes a look at a hospital with Linux thin clients for patients. "The happy healers at Glendale Adventist Medical Center, in conjunction with Linux luminaries IBM and Novell, as well as the networkers at NoMachine, have found a way to insert Linux into the lives of its patients. Rather than blank walls and bad TV to stare at, patients in the new West Tower at Glendale Adventist have access to the outside world, via Linux-based thin clients available right in the patient's room. The setup utilizes servers from IBM, the networking and compression expertise of NoMachine, and SUSE Linux Enterprise Desktop to provide patients with access to the internet, where they can do everything from learning about their condition and treatment to keeping family and friends abreast of their progress via the standard cast of internet characters: Twitter, Facebook, and the omnipresent blogs."

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CentOS has updated openswan (input validation flaws), pidgin (denial of service), ruby (denial of service).

Debian has updated nagios (arbitrary program execution).

Gentoo has updated libwmf (pointer use-after-free flaw), modsecurity (denial of service).

Red Hat has updated ruby (denial of service).

SUSE has updated java (multiple vulnerabilities), optipng, cups, quagga, pango, strongswan, perl-DBD-Pg, irssi, openssl/libopenssl-devel, net-snmp, ImageMagick/GraphicsMagick, perl, ipsec-tools/novell-ipsec-tools, poppler/libpoppler3/libpoppler4, yast2-ldap-server, tomcat6, gstreamer-plugins/gstreamer010-plugins-bad, apache2-mod_php5 (various issues).

Ubuntu has updated perl (buffer overflow), nagios (arbitrary program execution).

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IBM has announced the release of Milepost GCC, an extension to the GCC compiler which uses machine learning techniques to improve application performance on embedded processors. "'Our technology automatically learns how to get the best performance from the hardware -- whether mobile phones, desktops, or entire systems -- the software will run faster and use less energy,' noted Dr. Bilha Mendelson, Manager of Code Optimization Technologies at IBM Research - Haifa. 'We opened the compiler environment so it can access artificial intelligence and machine learning guidance to automatically determine exactly what specific optimizations should be used and when to apply them to ramp-up performance.'" The code can be downloaded from the Milepost site.

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Stable kernels 2.6.30.1, 2.6.29.6, and 2.6.27.26 have been released by the stable team. Each contains quite a number of patches (111, 35, and 32 respectively) all over the tree, some with security implications. The 2.6.29.6 release comes with an important note: "This is the last release of the 2.6.29 kernel series. All users are strongly suggested to move to the 2.6.30 release series at this time."

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Dave Philips reviews the Linux version of Pianoteq (commercial software) on Linux Journal. "On the 15th of May 2009 the Modartt company announced the release of version 3.0.3 of their award-winning Pianoteq, a professional-quality digital keyboard instrument created by an audio synthesis method known as physical modeling. The program is vastly praised by its users, but in order to feel the love you've had to run a Windows machine or a Mac box. Until now, that is. The latest release introduces various new attractions, and the one that interests me the most is support for a native Linux version."

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The Free Software Foundation Europe presents an interview with Smári McCarthy. "Stian Rødven Eide: One of the most profiled projects you have been involved with is the Fab Lab, having headed the Icelandic branch for over a year now. While best known for its use of 3D printers, the Fab Lab is actually a much broader concept that goes far beyond technical innovation. Can you tell us a bit about your work there, and what you hope to achieve? Smári McCarthy: There are two sides to the Fab Lab story. On the one hand, there’s the research side, which is all about developing the universal constructors, figuring out the hard science of digital fabrication. In that realm I think our work is done when we can download chicken sandwiches off the Internet."

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The July, 2009 edition of the GNOME Journal has been published. Contents include: "a review of Project Hamster by Les Harris, an interview on working with upstream with Laszlo Peter by Stormy Peters, using git for GNOME translators by Og Maciel, an introduction to GNOME Zeitgeist by Natan Yellin, a look at some of GNOME Do's advanced features by Jorge Castro, and lastly, the Behind the Scenes feature continues with Owen Taylor by Paul Cutler."

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CentOS has updated seamonkey (arbitrary code execution).

Fedora 9 has updated xorg-x11-xfs (race condition).

Fedora 10 has updated xorg-x11-xfs (race condition).

Red Hat Enterprise Linux has updated pidgin (denial of service) and openswan (input validation flaws).

Ubuntu has updated kernel (multiple vulnerabilities).

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iTWire reports on a new Linux installation by a Glendale, California hospital. "Adventist Medical Center (GAMC) has installed thin clients running Linux virtual desktops in 65 patient rooms in its new West Tower. "Just as easily as the hospital provides patients with TVs in rooms, now we provide personal computing," said Roger Pruyne, senior programmer/analyst and project manager for the GAMC Patient Computing project. The system combines NoMachine's NX remote access and virtualisation software, SUSE Linux Enterprise Desktop, and an IBM System x3650 server. GAMC estimates that this approach saves 98 percent of the cost that would have been involved if conventional PCs had been selected."

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