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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

Ubuntu: Infographic, New Releases, Ubuntu Podcast and Statistics

  • Infographic: Snaps in numbers
    Coinciding with the release of Ubuntu 18.10 today, we have celebrated the exceptional adoption of snaps by sharing the infographic below. From popular snaps to daily installs, this infographic demonstrates where, when and why users are installing and adopting the secure, Linux application format. For more commentary around these numbers, check out this recent blog. Alternatively, start installing your chosen snaps.
  • Ubuntu 18.10:Multi-cloud,new desktop theme & enhanced snap integration
    Canonical today announced the release of Ubuntu 18.10, focused on multi-cloud deployments, AI software development, a new community desktop theme and richer snap desktop integration. “Ubuntu is now the world’s reference platform for AI engineering and analytics” said Mark Shuttleworth, CEO of Canonical. “We accelerate developer productivity and help enterprises operate at speed and at scale, across multiple clouds and diverse edge appliances.” This year, the financial services industry has engaged significantly with Canonical and Ubuntu for infrastructure efficiency on-premise and to accelerate their move to the cloud. The push for machine learning analytics and of fintech efforts around blockchain, distributed ledger applications and cryptocurrencies are current drivers of Ubuntu investments and deployments.
  • Ubuntu Studio 18.10 Released
    The Ubuntu Studio team is pleased to announce the release of Ubuntu Studio 18.10 “Cosmic Cuttlefish”. As a regular release, this version of Ubuntu Studio will be supported for 9 months. Since it’s just out, you may experience some issues, so you might want to wait a bit before upgrading. Please see the release notes for a complete list of changes and known issues.
  • Ubuntu MATE: Ubuntu MATE 18.10 Final Release
    Ubuntu MATE 18.10 is a modest, yet strategic, upgrade over our 18.04 release. If you want bug fixes and improved hardware support then 18.10 is for you. For those who prefer staying on the LTS then everything in this 18.10 release is also important for the upcoming 18.04.2 release. Oh yeah, we've also made a bespoke Ubuntu MATE 18.10 image for the GPD Pocket and GPD Pocket 2.
  • Ubuntu Podcast from the UK LoCo: S11E32 – Thirty-Two Going on Spinster
    This week we interview Daniel Foré about the final release of elementary 5.0 (Juno), bring you some Android love and go over all your feedback. It’s Season 11 Episode 32 of the Ubuntu Podcast! Alan Pope and Martin Wimpress are connected and speaking to your brain.
  • Canonical have released some statistics from the Ubuntu installer survey
    When installing Ubuntu 18.04, Canonical's installer will offer to send some statistics to them. Canonical have now released some of this. One thing to note, is that this data does not include Ubuntu Server, Ubuntu Core, cloud images or and any other Ubuntu derivatives that don't include the report in their own installer. They've had some good results from it, with 66% of people sending them their data. It's a nice start, but I think they really need to do some separation of physical and virtual machines, since it seems they're merged together which will skew a bunch of the data I would imagine.

Linux-driven embedded PCs target autonomous cars

Kontron announced two Ubuntu-driven computers for autonomous vehicles. The S2000 is a lab dev platform with a Xeon 8160T and the EvoTRAC S1901 offers a choice of Kontron modules including a new Atom C3000 based, Type 7 COMe-bDV7R. Kontron has launched a Kontron’s S2000 Development Platform for developing autonomous in-vehicle computers and is prepping an EvoTRAC S1901 in-vehicle PC for use in advanced automotive applications, including autonomous vehicles. Both systems ship with Intel processors running a pre-installed Ubuntu 16.04 LTS Linux stack. The systems follow earlier Kontron automotive computers such as the EvoTrac G102 in-vehicle cellular gateway. Read more

OpenBSD 6.4 Released - Disables SMT/HT By Default, Updates Radeon DRM

Adding to the exciting release day is Theo de Raadt releasing OpenBSD 6.4 as the newest version of this BSD operating system known for its security mindfulness. Exciting us from a technical standpoint and for anyone using OpenBSD on the desktop is a newer Radeon DRM display driver, but it's still very dated compared to what is found in the mainline Linux kernel. Their Radeon DRM driver is now synced against the Linux 4.4.155 LTS upstream state that then provides mode-setting support for various GCN 1.0/1.1 graphics cards as a new feature to OpenBSD... But newer GPUs and the many other open-source AMD improvements past Linux 4.4 haven't made their way into the OpenBSD world yet. Even still, Radeon graphics remain among the best supported options for what is available to OpenBSD users. The Radeon DRM code is also now available for 64-bit ARM OpenBSD users. Read more Direct: OpenBSD 6.4 LWN: OpenBSD 6.4

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