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The venerable printk() function has been part of Linux since the very beginning, though it has undergone a fair number of changes along the way. Now, John Ogness is proposing to fundamentally rework printk() in order to get rid of handful of issues that currently plague it. The proposed code does this by adding yet another ring buffer implementation to the kernel; this one is aimed at making printk() work better from hard-to-handle contexts. For a task that seems conceptually simple—printing messages to the console—printk() is actually a rather complex beast; that won't change if these patches are merged, though many of the problems with the current implementation will be removed.

Security updates have been issued by Arch Linux (bind, kibana, systemd, and thunderbird), Debian (elfutils and liblivemedia), Fedora (kernel, kernel-headers, kernel-tools, and SDL), openSUSE (dovecot23, firefox, kauth, python-Jinja2, python-numpy, and thunderbird), Red Hat (java-1.8.0-openjdk and kernel), SUSE (python, python-amqp, python-oslo.messaging, python-ovs, python-paramiko, python-psql2mysql, qemu, and supportutils), and Ubuntu (ghostscript, gnome-keyring, and ldb).

Version 1.12 of the Go language has been released. "Some of the highlights include opt-in support for TLS 1.3, improved modules support (in preparation for being the default in Go 1.13), support for windows/arm, and improved macOS & iOS forwards compatibility". See the release notes for details.

Concurrency is hard even when the hardware's behavior is entirely deterministic; it gets harder in situations where operations can be reordered in seemingly random ways. In these cases, developers tend to reach for barriers as a way of enforcing ordering, but explicit barriers are tricky to use and are often not the best way to think about the problem. It is thus common to see explicit barriers removed as code matures. That now seems to be happening with an especially obscure type of barrier used with memory-mapped I/O (MMIO) operations.

Git v2.21.0 has been released. "It is comprised of 500 non-merge commits since v2.20.0, contributed by 74 people, 20 of which are new faces." The release notes are included in the announcement.

Version 8.3 of the GNU Compiler Collection has been released. "GCC 8.3 is a bug-fix release from the GCC 8 branch containing important fixes for regressions and serious bugs in GCC 8.2 with more than 153 bugs fixed since the previous release."

Security updates have been issued by Arch Linux (msmtp and python-mysql-connector), Debian (freedink-dfarc, rssh, sox, and waagent), Fedora (docker-latest, java-1.8.0-openjdk, koji, pagure, poppler, and spice), openSUSE (ansible, GraphicsMagick, mosquitto, pspp, spread-sheet-widget, and python-python-gnupg), Red Hat (chromium-browser), Slackware (file), SUSE (kernel, python-Django, qemu, and thunderbird), and Ubuntu (bind9).

Anybody expecting the 5.0 kernel to come out today will have been disappointed; Linus released 5.0-rc8 instead. "This may be totally unnecessary, but we actually had more patches come in this last week than we had for rc7, which just didn't make me feel the warm and fuzzies. And while none of the patches looked all that scary, some of them were to pretty core files, so it wasn't all just random rare drivers (although those kinds also existed)."

The latest updates from the stable kernel machine are 4.20.12, 4.19.25, 4.14.103, 4.9.160, 4.4.176, and 3.18.136. Each contains a relatively small set of important fixes.

Linus Torvalds once famously said that there is no design behind the Linux kernel. That may be true, but there are still some guiding principles behind the evolution of the kernel; one of those, to date, has been that the kernel does not recognize "containers" as objects in their own right. Instead, the kernel provides the necessary low-level features, such as namespaces and control groups, to allow user space to create its own container abstraction. This refusal to dictate the nature of containers has led to a diverse variety of container models and a lot of experimentation. But that doesn't stop those who would still like to see the kernel recognize containers as first-class kernel-supported objects.

Security updates have been issued by Mageia (libreoffice, libtiff, spice, and spice-gtk), openSUSE (build, mosquitto, and nodejs6), Red Hat (firefox, flatpak, and systemd), Scientific Linux (firefox, flatpak, and systemd), SUSE (kernel-firmware and texlive), and Ubuntu (bind9 and ghostscript).

The Linux Foundation has announced the formation of the Enabling Linux in Safety Applications (ELISA) project to create tools and processes for companies to use to build and certify safety-critical Linux applications. "Building off the work being done by SIL2LinuxMP project and Real-Time Linux project, ELISA will make it easier for companies to build safety-critical systems such as robotic devices, medical devices, smart factories, transportation systems and autonomous driving using Linux. Founding members of ELISA include Arm, BMW Car IT GmbH, KUKA, Linutronix, and Toyota. To be trusted, safety-critical systems must meet functional safety objectives for the overall safety of the system, including how it responds to actions such as user errors, hardware failures, and environmental changes. Companies must demonstrate that their software meets strict demands for reliability, quality assurance, risk management, development process, and documentation. Because there is no clear method for certifying Linux, it can be difficult for a company to demonstrate that their Linux-based system meets these safety objectives."

The announcement of the 5.0-rc7 kernel prepatch on February 17 signaled the imminent release of the final 5.0 kernel and the end of this development cycle. 5.0, as it turns out, brought in fewer changesets than its immediate predecessors, but it was still a busy cycle with a lot of developers participating. Read on for an overview of where the work came from in this release cycle.

Security updates have been issued by CentOS (firefox, flatpak, and systemd), Fedora (createrepo_c, dnf, dnf-plugins-core, dnf-plugins-extras, docker, libcomps, libdnf, and runc), Mageia (giflib, irssi, kernel, kernel-linus, libexif, poppler, tcpreplay, and zziplib), and SUSE (php5, procps, and qemu).

The LWN.net Weekly Edition for February 21, 2019 is available.

On his blog, Karim Yaghmour writes about an experimental social network that he and a colleague cobbled together using Git. While it is simply a proof of concept at this point, he is looking for feedback and, perhaps, collaborators to take it further. "It turns out that git has practically everything that's needed to act both as storage and protocol for a social network. Not only that, but it's very well-known within and used, deployed and maintained in the circles I navigate, it scales very well (see github), it's used for critical infrastructure (see kernel.org), it provides history, it's distributed by nature, etc. It's got *almost* everything, but not quite everything needed. So what's missing from git? A few basic things that it turns out aren't very hard to take care of: ability to 'follow', getting followee notifications, 'commenting' and an interface for viewing feeds. And instead of writing a whole online treatise of how this could be done, I asked my colleague Francois-Denis Gonthier to implement a proof and concept of this that we called 'gitgeist' and just published on github [https://github.com/opersys/gitgeist-poc]."

These days applications are generally moving away from the desktop and toward the mobile space. But taking a multi-platform desktop application and adding two mobile platforms into the mix is difficult to do, as Dirk Hohndel described in his linux.conf.au 2019 talk. Hohndel maintains the Subsurface dive log application, which has added mobile support over the past few years; he wanted to explain the process that the project went through to support all of those platforms. As the subtitle of the talk, "Developing for multiple platforms without losing your mind", indicates, it is a hard problem to solve sanely.

Stable kernels 4.20.11, 4.19.24, 4.14.102, 4.9.159, 4.4.175, and 3.18.135 have been released. They all contain important fixes and users should upgrade.

Security updates have been issued by Debian (ansible, drupal7, and systemd), Fedora (botan2, ceph, and firefox), Oracle (firefox, flatpak, and systemd), Red Hat (firefox), SUSE (gvfs, kernel, libqt5-qtbase, python-numpy, and qemu), and Ubuntu (gdm3).

The digiKam team has announced the release of digiKam 6.0.0. New features include full support of video files management working as photos; an integration of all import/export web-service tools in LightTable, Image editor and Showfoto; raw file decoding engine supporting new cameras; similarity data is now stored in a separate file; simplified web-service authentication using OAuth protocol; and more.