Loris Cro has published a detailed YouTube video talking about the terminology used to discuss asynchronicity, concurrency, and parallelism in our recent article about Zig's new Io interface. Our article is not completely clear because it uses the term "asynchronous I/O" to refer to what should really be called "non-blocking I/O", and sometimes confuses asynchronicity for concurrency, among other errors of terminology, he says. Readers interested in precise details about Zig's approach and some of the motivation behind the design may find Cro's video interesting.

Inside this week's LWN.net Weekly Edition:

• Front: Rust in Debian; Python comprehensions; asynchronous Zig; BPF and io_uring; C safety; 6.18 statistics; just.
• Briefs: Landlock; Let's Encrypt lifetimes; Last 5.4 kernel; TAB election; AlmaLinux 10.1; FreeBSD 15.0; NixOS 25.11; Django 6.0; Home Assistant 2025.12; PHP 8.5.0; Racket 9.0; Quotes; ...
• Announcements: Newsletters, conferences, security updates, patches, and more.

Version 2025.12 of the Home Assistant home-automation system has been released.

This month, we're unveiling Home Assistant Labs, a brand-new space where you can preview features before they go mainstream. And what better way to kick it off than with Winter mode? ❄️ Enable it and watch snowflakes drift across your dashboard. It's completely unnecessary, utterly delightful, and exactly the kind of thing we love to build. ❄️

But that's just the beginning. We've been working on making automations more intuitive over the past releases, and this release finally delivers purpose-specific triggers and conditions. Instead of thinking in (numeric) states, you can now simply say "When a light turns on" or "If the climate is heating". It's automation building the way our mind works, as it should be.

The Django Python web framework project has announced the release of Django 6.0 including many new features, as can be seen in the release notes. Some highlights include template partials for modularizing templates, a flexible task framework for running background tasks, a modernized email API, and a Content Security Policy (CSP) feature that provides the ability to "easily configure and enforce browser-level security policies to protect against content injection".

Over time, many Linux users wind up with a collection of aliases, shell scripts, and makefiles to run simple commands (or a series of commands) that are often used, but challenging to remember and annoying to type out at length. The just command runner is a Rust-based utility that just does one thing and does it well: it reads recipes from a text file (aptly called a "justfile"), and runs the commands from an invoked recipe. Rather than accumulating a library of one-off shell scripts over time, just provides a cross-platform tool with a framework and well-documented syntax for collecting and documenting tasks that makes it useful for solo users and collaborative projects.

Security updates have been issued by Debian (containerd, mako, and xen), Fedora (forgejo, nextcloud, openbao, rclone, restic, and tigervnc), Oracle (firefox, kernel, libtiff, libxml2, and postgresql), SUSE (libecpg6, lightdm-kde-greeter, python-cbor2, python-mistralclient-doc, python315, and python39), and Ubuntu (kdeconnect, linux, linux-aws, linux-realtime, python-django, and unbound).

Greg Kroah-Hartman has announced the release of the 5.4.302 stable kernel:

This is the LAST 5.4.y release. It is now end-of-life and should not be used by anyone, anymore. As of this point in time, there are 1539 documented unfixed CVEs for this kernel branch, and that number will only increase over time as more CVEs get assigned for kernel bugs.

For the curious, Kroah-Hartman has also provided a list of the unfixed CVEs for 5.4.302.

Let's Encrypt has announced that it will be reducing the validity period of its certificates from 90 days to 45 days by 2028:

Most users of Let's Encrypt who automatically issue certificates will not have to make any changes. However, you should verify that your automation is compatible with certificates that have shorter validity periods.

To ensure your ACME client renews on time, we recommend using ACME Renewal Information (ARI). ARI is a feature we've introduced to help clients know when they need to renew their certificates. Consult your ACME client's documentation on how to enable ARI, as it differs from client to client. If you are a client developer, check out this integration guide.

If your client doesn't support ARI yet, ensure it runs on a schedule that is compatible with 45-day certificates. For example, renewing at a hardcoded interval of 60 days will no longer be sufficient. Acceptable behavior includes renewing certificates at approximately two thirds of the way through the current certificate's lifetime.

Manually renewing certificates is not recommended, as it will need to be done more frequently with shorter certificate lifetimes.

FreeBSD 15.0 has been released. Notable changes in this release include a new method for installing the base system using the pkg package manager, an update to OpenZFS 2.4.0-rc4, native support for the inotify(2) interface, and the addition of Open Container Initiative (OCI) images to FreeBSD's release artifacts. See the release notes for a full list of changes, hardware notes for supported hardware, and check the errata before installing or upgrading.

The designers of the Zig programming language have been working to find a suitable design for asynchronous code for some time. Zig is a carefully minimalist language, and its initial design for asynchronous I/O did not fit well with its other features. Now, the project has announced (in a Zig SHOWTIME video) a new approach to asynchronous I/O that promises to solve the function coloring problem, and allows writing code that will execute correctly using either synchronous or asynchronous I/O.

Security updates have been issued by Fedora (gnutls, libpng, mingw-python3, python-spotipy, source-to-image, unbound, and webkitgtk), Mageia (libpng), SUSE (bash-git-prompt, gitea-tea, java-17-openjdk, java-21-openjdk, kernel, openssh, python, and shadowsocks-v2ray-plugin, v2ray-core), and Ubuntu (binutils, openjdk-17-crac, openjdk-21-crac, and openjdk-25-crac).

There are many possible programmer mistakes that are not caught by the minimal checks specified by the C language; among those is passing an array of the wrong size to a function. A recent attempt to add some safety around array parameters within the crypto layer involved the use of some clever tricks, but it turns out that clever tricks are unnecessary in this case. There is an obscure C feature that can cause this checking to happen, and it is already in use in a few places within the kernel.

Linus Torvalds released the 6.18 kernel as expected on November 30, closing the last full development cycle of 2025. It was another busy cycle, featuring a record number of developers. The time has come for a look at where the code came from for this kernel release, but also for the year-long long-term-support cycle which has also reached its conclusion with this release.

Security updates have been issued by AlmaLinux (bind9.18, cups, gimp, ipa, kernel, libssh, mingw-expat, openssl, pcs, sssd, tigervnc, and valkey), Debian (gnome-shell-extension-gsconnect, mistral-dashboard, pagure, python-mistralclient, pytorch, qtbase-opensource-src, sogo, tryton-server, and unbound), Fedora (cef, drupal7, glib2, linux-firmware, migrate, pack, pgadmin4, rnp, and unbound), Slackware (libxslt), SUSE (cpp-httplib, curl, glib2, grub2, kernel, libcoap-devel, libcryptopp, libwireshark19, postgresql15, and postgresql17), and Ubuntu (edk2).

Greg Kroah-Hartman has announced the release of the 6.17.10, 6.12.60, and 6.6.118 stable kernels. As usual, each contains a number of important fixes throughout the tree. Users are advised to upgrade.

Linus has released the 6.18 kernel, as expected.

So I'll have to admit that I'd have been happier with slightly less bugfixing noise in this last week of the release, but while there's a few more fixes than I would hope for, there was nothing that made me feel like this needs more time to cook. So 6.18 is tagged and pushed out.

Headline changes in this release include the ability to manage namespaces with file handles, support for the AccECN congestion-control protocol, initial support for signing of BPF programs, improved memory management with sheaves, the Rust binder driver, better control over transparent huge pages, and a lot more. This release also saw the removal of the bcachefs filesystem.

See the LWN merge-window summaries (part 1, part 2) and the KernelNewbies 6.18 page for more information.

Version 25.11 of the NixOS distribution has been released. "The 25.11 release was made possible due to the efforts of 2742 contributors, who authored 59430 commits since the previous release". Changes include 7,002 new packages, GNOME 49, LLVM 21, a new COSMIC desktop environment beta, firewalld support, and more; see the release notes for details.

The prizrak.me blog is carrying an introduction to the Landlock security module.

Landlock shines when an application has a predictable set of files or directories it needs. For example, a web server could restrict itself to accessing only /var/www/html and /tmp.

Unlike SELinux or AppArmor, Landlock policies don't require administrator involvement or system-wide configuration. Developers can embed policies directly in application code, making sandboxing a natural part of the development process.

Security updates have been issued by Debian (krita and tryton-server), Oracle (bind9.18, ipa, kernel, libssh, redis, redis:7, sqlite, sssd, and vim), Slackware (cups), SUSE (containerd, cups, curl, dovecot24, git-bug, gitea-tea, glib2, grub2, himmelblau, java-25-openjdk, kernel, libmicrohttpd, libvirt, pnpm, powerpc-utils, python311, python313, redis, rnp, runc, sssd, tomcat11, unbound, and xwayland), and Ubuntu (cups, libxml2, openvpn, and webkit2gtk).

Security updates have been issued by Debian (kdeconnect, libssh, and samba), Fedora (7zip, docker-buildkit, and docker-buildx), Oracle (bind, buildah, cups, delve and golang, expat, firefox, gimp, go-rpm-macros, haproxy, kernel, lasso, libsoup, libtiff, mingw-expat, openssl, podman, python-kdcproxy, qt5-qt3d, runc, squid, thunderbird, tigervnc, valkey, webkit2gtk3, xorg-x11-server, and xorg-x11-server-Xwayland), SUSE (buildah, cloudflared, containerd, expat, firefox, gnutls, helm, kernel, libxslt, mysql-connector-java, ongres-scram, openbao, openexr, openssh, podman, python311, python312, ruby2.5, rubygem-rack, runc, samba, sssd, tiff, unbound, and yelp), and Ubuntu (edk2, ffmpeg, h2o, python3.13, rust-openssl, and valkey).