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Latest LWN Articles About Linux (Paywall Has Just Expired)

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Linux
  • SPDX identifiers in the kernel

    Observers of the kernel's commit stream or mailing lists will have seen a certain amount of traffic referring to the addition of SPDX license identifiers to kernel source files. For many, this may be their first encounter with SPDX. But the SPDX effort has been going on for some years; this article describes SPDX, along with why and how the kernel community intends to use it.

    On its face, compliance with licenses like the GPL seems like a straightforward task. But it quickly becomes complicated for a company that is shipping a wide range of software, in various versions, in a whole set of different products. Compliance problems often come about not because a given company wants to flout a license, but instead because that company has lost track of which licenses it needs to comply with and for which versions of which software. SPDX has its roots in an effort that began in 2009 to help companies get a handle on what their compliance obligations actually are.

    It can be surprisingly hard to determine which licenses apply to a given repository full of software. The kernel's COPYING file states that it can be distributed under the terms of version 2 of the GNU General Public License. But many of the source files within the kernel tell a different story; some are BSD licensed, and many are dual-licensed. Some carry an exception to make it clear that user-space programs are not a derived product of the kernel. Occasionally, files with GPL-incompatible licenses have been found (and fixed).

  • 4.15 Merge window part 1

    When he released 4.14, Linus Torvalds warned that the 4.15 merge window might be shorter than usual due to the US Thanksgiving holiday. Subsystem maintainers would appear to have heard him; as of this writing, over 8,800 non-merge changesets have been pulled into the mainline since the opening of the 4.15 merge window. Read on for a summary of the most interesting changes found in that first set of patches.

  • 4.15 Merge window part 2

    Despite the warnings that the 4.15 merge window could be either longer or shorter than usual, the 4.15-rc1 prepatch came out right on schedule on November 26. Anybody who was expecting a quiet development cycle this time around is in for a surprise, though; 12,599 non-merge changesets were pulled into the mainline during the 4.15 merge window, 1,000 more than were seen in the 4.14 merge window. The first 8,800 of those changes were covered in this summary; what follows is a look at what came after.

  • BPF-based error injection for the kernel

    Diligent developers do their best to anticipate things that can go wrong and write appropriate error-handling code. Unfortunately, error-handling code is especially hard to test and, as a result, often goes untested; the code meant to deal with errors, in other words, is likely to contain errors itself. One way of finding those bugs is to inject errors into a running system and watching how it responds; the kernel may soon have a new mechanism for doing this sort of injection.

    As an example of error handling in the kernel, consider memory allocations. There are few tasks that can be performed in kernel space without allocating memory to work with. Memory allocation operations can fail (in theory, at least), so any code that contains a call to a function like kmalloc() must check the returned pointer and do the right thing if the requested memory was not actually allocated. But kmalloc() almost never fails in a running kernel, so testing the failure-handling paths is hard. It is probably fair to say that a large percentage of allocation-failure paths in the kernel have never been executed; some of those are certainly wrong.

  • Tools for porting drivers

    Out-of-tree drivers are a maintenance headache, since customers may want to use them in newer kernels. But even those drivers that get merged into the mainline may need to be backported at times. Coccinelle developer Julia Lawall introduced the audience at Open Source Summit Europe to some new tools that can help make both forward-porting and backporting drivers easier.

    She opened her talk by noting that she was presenting step one in her plans, she hoped to be able to report on step two next year some time. The problem she is trying to address is that the Linux kernel keeps moving on. A vendor might create a driver for the 4.4 kernel but, over the next six months, the kernel will have moved ahead by another two versions. There are lots of changes with each new kernel, including API changes that require driver changes to keep up.

    That means that vendors need to continually do maintenance on their drivers unless they get them upstream, where they will get forward-ported by the community. But the reverse problem is there as well: once a device becomes popular, customers may start asking for it to run with older kernels too. That means backporting.

More in Tux Machines

OSS Leftovers

  • OpenStack regroups
    Only a few years ago, OpenStack was the hottest open-source project around, with a bustling startup ecosystem to boot. The project, which gives enterprises the tools to run the equivalent of AWS in their own private data centers, ran into trouble as it tried to tackle too many individual projects at the same time and enterprises took longer than expected to adopt it. That meant many a startup floundered or was acquired before it was able to gain traction while the nonprofit foundation that manages the project started to scale back its big tent approach and refocused on its core services.
  • SD Times news digest: Docker and MuleSoft’s partnership, ActiveState’s open-source language automation category, and Instana’s automatic Python instrumentation
    Docker and MuleSoft have announced a new partnership to modernize applications and accelerate digital transformation. As part of the partnership, the companies will work together to deliver new capabilities for legacy apps with APIs, legacy apps without APIs and new apps created in Docker. In addition, MuleSoft’s Anypoint platform will be combined with Docker Enterprise.
  • ActiveState Creates Open Source Language Automation Category
  • New open source cloud discovery tool arrives from Twistlock
    Cloud Discovery connects to cloud providers' native platform APIs to discover services such as container registries, managed Kubernetes platforms, and serverless services, and requires only read permissions. Other key features include:
  • Google Open-Sources "Amber" Multi-API Shader Test Framework
    The newest open-source graphics project out of Google is called Amber and it's a multi-API shader testing framework focused on capturing and communicating of shader bugs. Google's Amber tries to make it easier to capture/communicate shader bugs with a scripting-based workflow. The captured shaders can be in binary form, SPIR-V assembly, or a higher-level shading language. Amber is currently focused on supporting the Vulkan and Dawn graphics APIs.
  • Microsoft allies with Facebook on AI software [Ed: Evil likes/attracts evil. Now they can do their crimes together while blaming "AI". Longtime Microsoft propagandist Jordan Novet has decided to add the Microsoft lie (PR campaign) "Microsoft loves Linux" (in photo form) to an article that has nothing to do with Linux.]
  • Microsoft alliance with Facebook signals shift in AI approach

Android Leftovers

Security Leftovers

Devices: Adding Linux to A PDP-11, Adding GNU/Linux Software to Chrome OS, and Adding Ubuntu to Android

  • Adding Linux To A PDP-11
    The UNIBUS architecture for DEC’s PDPs and Vaxxen was a stroke of genius. If you wanted more memory in your minicomputer, just add another card. Need a drive? Plug it into the backplane. Of course, with all those weird cards, these old UNIBUS PDPs are hard to keep running. The UniBone is the solution to this problem. It puts Linux on a UNIBUS bridge, allowing this card to serve as a memory emulator, a test console, a disk emulator, or any other hardware you can think of. The key to this build is the BeagleBone, everyone’s second-favorite single board computer that has one feature the other one doesn’t: PRUs, or a programmable real-time unit, that allows you to blink a lot of pins very, very fast. We’ve seen the BeagleBone be used as Linux in a terminal, as the rest of the computer for an old PDP-10 front panel and as the front end for a PDP-11/03.
  • Chrome OS Linux apps will soon be able to access your entire Downloads folder and Google Drive
    Google is working hard to turn Chrome OS into more than just a browser, but a real, functional operating system for consumers of all kinds. Most recently, they’ve invited developers to the platform with Linux app support that enables all of their tools, including Android Studio, to work as expected. Soon, your Chrome OS and Google Drive files will be even more accessible to your Linux apps. [...] According to a new commit on the Chromium Gerrit, that’s all about to change. The commit primarily pertains to a new dialog that will be shown when sharing ‘root’ folders like My Drive or Downloads with your Chrome OS Linux apps (internally known as Crostini) container. The dialog is intended to forewarn you that sharing a root folder is a bit more serious than just sharing a sub-folder, and to be sure you know what you’re doing.
  • Samsung Note 9 and Tab S4 owners can run a full Ubuntu Desktop – Linux on Dex
    We have come a long way as an industry and if this is not one of the biggest milestones in personal computing, I don’t know what else qualifies. Over the past decade of smartphones being around, we have seen an exponential increase in the power that our smartphones pack. I mean, flagships from the past few years spot more RAM and processing power than most laptops out there, but the small form factor has always been a hindrance to the utilization of this power. I mean you can only do so much on a 5.5-inch display. Samsung has launched its “Linux on Dex” app in beta and is inviting geeks and tinkerers to register and help test and develop it. The app lets owners of specific Samsung devices “run” a full Ubuntu desktop on their device alongside Android.