Category: Linux

  • While there are some developers who are familiar with using Ecore_Evas to create a canvas for applications, we often find that new EFL users face some confusion when first trying to create an application. This article aims to provide a simple example of how to create your first EFL Wayland application. For those not familiar with the Ecore_Evas library, it is a set of functions that make it easy to tie together Ecore’s main loop and input handling to Evas; as such, it’s a natural base for EFL applications. While this combination makes it easy to create the basic aspects all applications need, for normal applications (those that use buttons, checkboxes and layouts) one should consider using Elementary. Ecore_Evas is extremely well suited for applications that are not based on widgets. It has a main loop that delivers events, does basic window handling, and leaves all of the drawing up […]

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  • December 15, 2016 - Javier Martinez Canillas

    Samsung OSG Contributions to Linux Kernel 4.9

    Linux 4.9 was released on December 11, making this release the biggest to date in number of changes. In this development cycle, the Samsung Open Source Group (OSG) contributed 394 patches that modified 15,856 lines of code. Although 4 engineers contributed to different Kernel subsystems, most of the changes comes again from Mauro Carvalho Chehab’s work to improve the Linux kernel documentation. The following is a list of the OSG engineers that contributed to this release and the number of changesets and lines of code, as reported by Jonathan Corbet and Greg Kroah-Hartman’s gitdm tool. OSG developers by changesets Mauro Carvalho Chehab 238 60.4% Javier Martinez Canillas 108 27.4% Shuah Khan 24 6.1% Luis de Bethencourt 24 6.1% OSG developers by changed lines Mauro Carvalho Chehab 14,747 93.0% Javier Martinez Canillas 518 3.3% Shuah Khan 314 2.0% Luis de Bethencourt 277 1.7% OSG Contributions to This Release On this release, […]

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  • The Linux kernel contains a set of developer unit and regression tests (Kselftests) under tools/testing/selftests; these tests exercise individual code paths in the kernel. In this blog post, I’ll explain how to build and run these tests, run Kselftest on a system it’s built on, and how to install and run tests on a target test system. Even though kselftest’s main purpose is for developer regression test, testers and users can also use it to ensure there are no regressions in a new kernel. Kselftest is run everyday on several Linux kernel trees on the 0-Day and kernelci.org Linux kernel integration test rings. How to Build Kselftest The tests are intended to be run after building, installing, and booting a kernel.

    Boot the new kernel, then execute the following

    Please note, some tests require root privileges. You can run a subset of selftests using “TARGETS” make command […]

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  • After finishing high school, I was destined to continue my academic life studying one of the fine arts I always loved: Architecture. I took special art classes to get prepared to study it, and so I did; I entered the architectural school at my hometown in the Canary Islands. In their first year, all students learn about the Bauhaus school and their impact. I knew about them, but in that year I learned about their philosophy in detail and I became sanely obsessed with their work. During their difficult social/political time, Bauhaus revolutionized the world of architecture, design, and art. Their modernist designs were centered in functionality, simplicity, rationality, and taking art to everybody through mass production. In summary, making our day to day habitats and tools better, cheaper, simpler, and available to all. So through most of my first year I asked myself “Where is the present-day Bauhaus?” I […]

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  • November 4, 2016 - Chris Michael

    Ecore_Wl2: An EFL Library for Wayland Applications

    Throughout the years of developing Wayland support for EFL, few EFL libraries have had as much impact on EFL Wayland applications as the Ecore_Wayland library has. This library was one of the first to make it possible to truly run EFL applications in a Wayland environment. As the years progressed, it became apparent that Ecore_Wayland had some shortcomings; this blog post will introduce you to the replacement for Ecore_Wayland, called Ecore_Wl2. Ecore_Wayland’s Shortcomings While testing our first Wayland implementation, it became apparent that the initial implementation of the Ecore_Wayland library had some drawbacks. Publicly exposed structures could not be changed easily without breaking existing applications, and any changes to existing Wayland protocols would require significant changes to our Ecore_Wayland library. It was also discovered that when an EFL Wayland application creates a new window, the backend library also creates an entirely new display and connection to the Wayland server. This […]

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  • November 3, 2016 - Bryce Harrington

    Compose Key Support in Weston

    I recently added support to Weston for compose sequences via the configured compose key. This is now available in all of the Weston clients. What are “compose sequences”? Let’s say I need to write to someone named Zoë, but I don’t have an “ë” key on my keyboard. I can create the letter using separate key strokes:

    The first key, RAlt (the Alt key on the right side of the keyboard), is the compose key (also called the Multi-key). It signals that a compose sequence is beginning. The next key is double-quote, constructed by holding one of the Shift keys while pressing the single-quote key. Third we type the letter e. This completes the sequence. Or, more correctly, the system finds a match for this sequence in a table of available sequences, and thus considers it finished. The entry in the table indicates that the ‘ë’ symbol should be […]

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  • November 1, 2016 - Shuah Khan

    Beware of Ubuntu 16.10 Upgrade Woes

    I wanted to share a word of caution for anybody planning to update their development and test systems to Ubuntu 16.10: I can’t build kernels anymore. Ubuntu recommends a special patch to the kernel Makefile. This patch will work only on Ubuntu kernel sources and not the upstream Linux kernel trees. Linux kernel builds fail with the following message

    The message about CONFIG_CC_STACKPROTECTOR_STRONG is misleading because this Kernel config option is enabled in most distro kernels; disabling it won’t solve the kernel build failure problem. It fails because the position independent executable option is set as default in gcc version 6.2.0 20161005 (Ubuntu 6.2.0-5ubuntu12). As a result, Linux Kernel Makefile needs to update to build the kernel with “-fno-pie” option. The Ubuntu 16.10 release notes say We have modified GCC to by-default compile programs with position independent executable support to improve the security benefits provided by Address Space Layout Randomization. This may cause […]

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  • October 28, 2016 - Mauro Carvalho Chehab

    Improving Linux Kernel Development Process Documentation

    This article will cover how the Linux kernel community handled the conversion of documentation related to the kernel development process; it’s part of a series on improvements being made to Linux kernel documentation. Introduction It’s not an easy task to properly describe the Linux development process. The kernel community moves at a very fast pace and produces about 6 versions per year. Thousands of people, distributed worldwide, contribute to this collective work; the development process is a live being that constantly adjusts to what best fits the people involved in the process. Additionally, since kernel development is managed per subsystems, each maintainer has their own criteria for what works best for the subsystem they take care of. To address this, the documentation provides a common ground for understanding the best practices all kernel developers should follow. The Documentation/Development-Process Book There are several files inside the kernel that describes the development […]

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  • October 26, 2016 - Chris Michael

    Ecore_Drm2: How to Use Atomic Modesetting

    In a previous article, I briefly discussed how the Ecore_Drm2 library came into being. This article will expand on that article and provide a brief introduction to the Atomic Modesetting and Nuclear Pageflip features inside the new Ecore_Drm2 library. What Makes Atomic Modesetting and Nuclear Pageflip so Great? For those that are unaware of what “modesetting” is, you may read more about it here. Atomic Modesetting is a feature that allows for output modes (resolutions, refresh rate, etc) to be tested in advance on a single screen or on multiple outputs. A benefit of this feature is that the given mode may be tested prior to being applied. If the test of a given output mode fails, the screen image doesn’t need to be changed to confirm a given mode works or not, thus reducing screen flickering. Atomic/Nuclear Pageflipping allows for a given scanout framebuffer object and/or one or more hardware […]

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  • The Light Display Manager doesn’t start on Odroid XU4 on the recent mainline kernels with exynos_defconfig. I first noticed this problem during the Linux 4.8 rc testing and this problem persists in 4.9-rc1. I want to share the root-cause, and a work-around in this post. I’m running kernel 4.9.0-rc1 with exynos_defconfig on Ubuntu 16.04 with HDMI. Light Display Manager (lightdm) fails with the following errors.

    This block repeats a few times until systemd gives up on starting lightdm. The system is operational with functioning serial console and networking, however the display doesn’t work. What Causes this problem? The following sequence of events is what leads to this problem The user space calls exynos_drm_gem_create_ioctl() with the EXYNOS_BO_NONCONTIG request to allocate GEM buffers. exynos_drm_gem_create() creates non-contiguous GEM buffers as requested. exynos_user_fb_create() comes along later and validates the GEM buffers to associate them to frame-buffer. The validation in check_fb_gem_memory_type() detects non-contiguous buffers […]

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