Category: Linux

  • When debugging kernel problems that aren’t obvious, it’s necessary to understand the history of changes to the source files. For example, a race condition that results in a lockdep warning might have tentacles into multiple code paths. This requires us to examine and understand not only the changes made, but also why they were made. Individual patch commit logs are the best source of the information on why a change was made. So how do we find this information? My goto tool set for such endeavors has been a combination of git gui and git log. Recently I started using cregit. I will go over these options in this blog. git log Running git log on a source file will show all the commits for that file, then you can find the corresponding code change by generating the patch. Using git log can be tedious, but useful for targeted commit […]

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  • In the upcoming Linux 4.14-rc3 release, work continues to develop the Kselftest TAP13 framework API and convert tests to TAP13. The new tests include Kselftest common RUN_TESTS in that have been enhanced to print TAP13 to cover test shell scripts that won’t be able to use the Kselftest TAP13 API; this also covers test programs that aren’t converted yet. Several fixes have been made to existing tests to prevent failure in unsupported cases as part of an ongoing work based on feedback from Kselftest stable release users that don’t want the tests to fail due to unmet dependencies, such as config options being disabled. Additionally, a new watchdog test has been added and much needed cleanups to the existing watchdog tests have been made by Eugeniu Rosca. A New Kselftest Use-Case A notable change in this release is new support for the “make O=dir kselftest” use-case.  Several developers rely on this […]

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  • October 5, 2017 - Mike Blumenkrantz

    How to Create an EFL Gadget Sandbox

    The new gadget API and infrastructure for Enlightenment continue to undergo heavy development. In addition to improving and extending the base gadget UI, work has recently begun on creating a gadget provider with the new API to provide sandboxing and allow gadgets to be written as regular applications that don’t have or require access to compositor internals. The primary enabler of the new sandboxing system is the efl-wl compositor widget. This allows the compositor to launch applications in isolation, and also provides the ability to add protocol extensions for only that specific instance of the compositor widget. Using these features, it becomes possible to add gadget-specific protocols and utilities on the compositor side that are passed through transparently to the client gadget application. Currently, there is one base protocol in use: the e-gadget protocol, which looks like this:

    The purpose of this is to mimic the gadget API. Applications […]

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  • August 2, 2017 - Bryce Harrington

    Better Attachment Handling with Mutt

    The Mutt email client is famed for its extensive configuration options, but since it’s text-based, certain things are more challenging to do when compared to its graphical brethren. Viewing attachments is one such annoyance; fortunately, as with most things, Mutt is extensively configurable! By default, Mutt does fine with most plain text documents, and depending on your installation may also handle HTML documents in some fashion. Attachments that Mutt doesn’t recognize can of course be downloaded and viewed manually, but we can do better. To tell Mutt that it should handle a new attachment type, or its “MIME type”, we associate it with Mutt’s “auto_view” parameter. For example, add this to your ~/.muttrc (and restart Mutt):

    Note: if you plan to add a number of file types, you may wish to put these in their own config file (e.g. ~/.mutt/auto-views), and include a line in ~/.muttrc like the following: […]

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  • July 28, 2017 - Shuah Khan

    Kselftest for Linux 4.13 to Include TAP13

    Linux 4.13-rc1 was released on July 15th 2017  and it includes enhancements to the Kselftest framework to support The Test Anything Protocol v13 (TAP13). TAP13 defines a human friendly output format for tests. Kselftest is run in test rings and is widely used for Linux kernel stable release regression testing. It’s important to make it easier to identify run-to-run differences; TAP13 adaption makes it easier to understand the test results, and helps pin point differences between one run to another run of the test suite. Credit goes to Tim Bird for recommending TAP13 as a suitable format, and to Greg KH for kick starting the work with help from Paul Elder and Alice Ferrazzi. The first phase of the TAP13 conversion is included in Linux 4.13. Future releases will include updates to rest of the tests. The following shows membarrier test results before and after TAP 13 conversion: Before:

    After: […]

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  • July 18, 2017 - Bryce Harrington

    Introduction to GPG Encryption and git-crypt

    While Open Source prides itself on open transparency, there are certain things that must be kept secret like team credentials or personal information.  GNU’s OpenPGP (GPG) encryption tool set coupled with git-crypt can be invaluable for sharing such information privately with colleagues. For people unfamiliar with GPG it can seem a bit intimidating to start with, but it needn’t be! This article is a step-by-step introduction to getting set up with your own GPG key. Install GPG Since GPG has become pretty ubiquitous it should be straightforward to install via the usual method for your operating system. debian/ubuntu:

    OSX (using ports):

    etc. Create Your Own GPG Key Easy enough! The following command will ask for the info needed to make the key. Pick RSA with a key length of 4096 bits, and be very careful to set a unique GPG password that you’re not using anywhere else (but pick one you can remember!):


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  • As you might already know, many open source projects are moving away from autotools as a build system and are embracing Meson. GStreamer was one of the first projects to initiate this move as the community pushed for it to happen. Meson has many advantages over autotools, but one I would like to talk about in this post is the notion of subprojects, which Meson introduces. Basically, thanks to this it’s easy to build several projects as if it was one; GStreamer has many components that were formerly independent in the build system, meaning that if you wanted to build the latest version of, say, gst-plugins-bad, you also needed to build GStreamer core and GStreamer base one way or another. Previously, we had some scripts to help with this process, but it was still necessary to clone and build everything separately and handle interdependency between things manually. Today, things are different when using […]

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  • Wayland: there have been many blog posts, articles, and news items about the new Linux display protocol. There have been developers working to extend the protocol for new and extremely helpful use cases, but new frontiers continue to be explored: putting a multiseat Wayland compositor into a toolkit widget. Due to Wayland’s philosophy of “build your own compositor,” there is no de-facto implementation of a Wayland display server that is analogous to Xorg for X11. Wayland implementations are written using the libwayland server API, and this is flexible enough to be used even in the case of a widget. Overall, the only noteworthy difference between putting a compositor in a widget and a normal nested compositor is that the output size is set to the size of the widget instead of the size of the window. With this in mind, a compositor widget can be manipulated just like any other […]

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  • The Tizen Developer Conference (TDC) is just around the corner; it will be held May 16 – 17 at the Hilton Union Square Hotel in San Francisco, CA. Our team contributes a ton of code to some of the critical open source software that makes up Tizen, so of course we’ll be spending some time there to network with app developers and device makers who work with Tizen. What’s Happening with Tizen? There has been quite a few exciting developments for Tizen over the last year; for starters Samsung joined forces with Microsoft to bring .NET to Tizen, allowing developers to build applications for Tizen using C# and Visual Studio. Additionally, Tizen has continued to show up on a growing number of consumer devices including the Gear S3, Z2,  Gear 360, AR9500M air conditioner, POWERbot VR7000, multiple smart TV’s, and more. Finally, Tizen RT was released last year, making it […]

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  • After my previous blog post, you should now be using SSH and Tor all the more often, but things are probably slow when you are trying to setup a secure connection with this method. This may well be due to your computer lacking a proper source of entropy to create secure cryptographic keys. You can check the entropy of your system with the following command.

    This will return a number, hopefully it’s above 3,000 because that’s what is likely needed to keep up with your needs. So what do you do if it’s not high enough? This article will cover two tips to improve your computer’s entropy. All examples in this guide are for Linux distributions that use systemd. rngd rngd is a tool designed to feed the system with more entropy from various sources. It is part of the rng-tools package. After installing it, the rngd service needs to […]

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