Category: Development

  • Memory usage is often overlooked as Moore’s law brings us larger amounts of memory year after year; still, it matters significantly for multiple reasons. First, even if the total memory available to an application has been increasing, speed and cache size haven’t. This means that the more memory an application has to walk, the more likely it is to step out of the cache and slow down the application, a problem for performance-critical tasks. There is a difference in latency access of two orders of magnitude to use cache vs. the main memory; for reference, you can use 1ns for a cache hit and 100ns for a memory access. Something else you might not realize is that fetching data from the memory subsystem consumes more energy than not doing so. Stating it like this seems obvious, but it’s true, consuming less memory also means consuming less energy. Some hardware can […]

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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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  • I want to use this short article to point out a big problem in code that uses libdrm. This, or a variant of this, is lurking in a shocking amount of software:

    Stop doing this, it has always been a crash waiting to happen. drmEventContext is part of libdrm’s ABI and there are strict promises that the structure won’t be randomly re-ordered. However, it may grow as the need arises when new versions of libdrm offer functionality which didn’t exist before. libdrm 2.4.78 introduces another page flip handler, adding a new function pointer harmlessly at the end of the structure page_flip_handler2. It also bumps DRM_EVENT_CONTEXT_VERSION from 2 to 3, as that’s the current version of the structure in the header file. As a result, the code above crashes… sometimes. What went wrong? The Proper Way to Use drmEventContext DrmEventContext.version is intended to tell the library what version of the […]

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  • April 10, 2017 - Ben Lloyd Pearson

    What Does the Samsung OSG Do?

    In case you haven’t heard the news, we’re currently on a quest to hire a new Linux Kernel engineer, so we thought this would be a good time to explain what our team does for Samsung. Samsung relies on open source software for the vast majority of products and services the company produces and as a result, it has become an imperative for the company to have a team dedicated to improving and leveraging open source software. Essentially, the OSG has two primary purposes. The first is to provide open source leadership within Samsung by helping other divisions in the company understand how to participate in and benefit from open source development. The second is to serve as Samsung’s representatives in the wider open source community. The mandate of this team is to focus on enhancing key open source projects and technologies via active contributions to them, and to be […]

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  • February 22, 2017 - Javier Martinez Canillas

    Samsung OSG Contributions to Linux Kernel 4.10

    Linux 4.10 was released on February 17; for this release, 6 engineers from the US and UK branches of the Samsung Open Source Group (OSG) contributed 341 patches that modified 44,709 lines of code. Again, most of the changes comes from Mauro Carvalho Chehab’s work to improve the Linux kernel documentation and fixing bugs all over the media tree. 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 231 67.7% Javier Martinez Canillas 77 22.6% Stefan Schmidt 11 3.2% Shuah Khan 11 3.2% Luis de Bethencourt 10 2.9% Derek Foreman 1 0.3% OSG developers by changed lines Mauro Carvalho Chehab 44,120 98.7% Luis de Bethencourt 162 0.4% Javier Martinez Canillas 156 0.3% Stefan Schmidt 145 0.3% Shuah Khan 92 0.2% Derek […]

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  • February 2, 2017 - Derek Foreman

    A Curious Wayland Bug

    Enlightenment has a slightly unconventional architecture. For many of its internal dialogues (settings, the file manager, etc.) it uses what we call “internal windows.” These are simply regular toolkit windows that use regular rendering back-ends; in the good ol’ days, this meant a connection to the X server which resulted in a render to a standard X window. In this scenario, the compositor gets the result back the same way as all X client windows, and it composites all internal and external windows together. Under Wayland, things get a bit scarier because now the compositor is the display server. Enlightenment makes a Wayland connection to itself; this gives us all manner of game winning capabilities we never had before. For example, let’s say the internal window wants to sleep and wait for a reply from the compositor (such as a released buffer to render the next frame into). We deadlock and fall down […]

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  • January 24, 2017 - Cedric Bail

    Improving the Security of Your SSH Configuration

    Most developers make use of SSH servers on a regular basis and it’s quite common to be a bit lazy when it comes to the admin of some of them. However, this can create significant problems because SSH is usually served over a port that’s remotely accessible. I always spend time securing my own SSH servers according to some best practices, and you should review the steps in this article yourself.  This blog post will expand upon these best practices by offering some improvements. Setup SSH Server Configuration The first step is to make the SSH service accessible via only the local network and Tor. Tor brings a few benefits for an SSH server: Nobody knows where users are connecting to the SSH server from. Remote scans need to know the hidden service address Tor uses, which reduces the risk of automated scan attacks on known login/password and bugs in the ssh server. It’s always […]

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  • 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 29, 2016 - Arun Raghavan

    Playback Synchronization & Video Walls with GStreamer

    Hello again, and I hope you’re having a pleasant end of the year (if you are, you might want to consider avoiding the news until next year). In a previous post, I wrote about synchronized playback with GStreamer, and work on this has continued apace. Since I last wrote about it, a bunch of work has been completed: Added support for sending a playlist to clients (instead of a single URI), Added the ability to start/stop playback, Cleaned up the API considerably to improve the potential for it to be included upstream, Turned the control protocol implementation into an interface to remove the necessity to use the built-in TCP server (different use-cases might want different transports), Improved overall robustness of code and documentation, Introduced an API for clients to send the server information about themselves, and finally Added an API for the server to send video transformations for each specific client to apply before rendering. […]

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  • If you’re reading this blog, you’re probably among the growing number of software professionals who understand how valuable open source development is to the production of modern technology. Many of us have seen how open source can reduce costs, increase development speed, increase overall product quality and more, but it can often be challenging to quantify the value of this using understandable metrics. Fortunately for us, open source development happens in public so a lot of information can be extracted from public resources such as git repository logs, email mailing lists, code review and bug tracking platforms, and more. One relatively new and useful tool to aide in this is GrimoireLab from Bitergia. We’ve spent the last few months exploring the capabilities of this tool to find out what kind of metrics we can use to track the success of the efforts of the Samsung Open Source Group. Doing so […]

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