Saying that calibre is ebook-management software undersells the application by a fair margin. Calibre is an open-source Swiss Army knife for ebooks that can be used for everything from creating ebooks, converting ebooks from obscure formats to modern formats like EPUB, to serving up an ebook library over the web. The most recent major release, calibre 8.0, brings a better text-to-speech engine, a tool for creating audio overlays when authoring ebooks, support for profiles in the ebook viewer, and more.

José Marchesi and David Faust kicked off the BPF track at the 2025 Linux Storage, Filesystem, Memory-Management, and BPF Summit with an extra-long session on what they have been doing to support compiling to BPF in GCC. Overall, the project is slowly working toward full support for BPF, with most of the self-tests now passing using Faust's in-progress patches. However, the progress toward that goal has turned up a number of problems with how Clang supports BPF that needed to be discussed at length to find a path forward for both projects.

Ryan Sipes has announced efforts to expand Thunderbird's offerings with web services to "enhance the experience of using Thunderbird".

The Why for offering these services is simple. Thunderbird loses users each day to rich ecosystems that are both clients and services, such as Gmail and Office365. These ecosystems have both hard vendor lock-ins (through interoperability issues with 3rd-pary clients) and soft lock-ins (through convenience and integration between their clients and services). It is our goal to eventually have a similar offering so that a 100% open source, freedom-respecting alternative ecosystem is available for those who want it.

The planned services include hosted email, appointment scheduling, a revival of Firefox Send, and (of course) an AI assistant based on a partnership with Flower AI. The AI features will "always be optional for use by people who want them". Sipes is managing director of product for Thunderbird's parent organization, MZLA Technologies Corporation. LWN covered his GUADEC 2024 keynote last July.

Outgoing Fedora Project Leader (FPL) Matthew Miller has announced his successor, Jef Spaleta.

Some of you may remember Jef's passionate voice in the early Fedora community. He got involved all the way back in the days of fedora.us, before Red Hat got involved. Jef served on the Fedora Board from July 2007 through the end of 2008. This was the critical time after Fedora Extras and Fedora Core merged into one Fedora Linux where, with the launch of the "Features" process, Fedora became a truly community-led project.

Spaleta will be joining Red Hat full time in May and Miller will be formally handing off FPL duties at the Flock conference in June.

Version 2.0 of PorteuX, a distribution based on Slackware Linux, has been released. This release adds the ability to test experimental Wayland sessions for the Cinnamon, LXQt, and Xfce desktops. PorteuX 2.0 updates the Linux kernel to 6.14 and includes many package updates and bug fixes. Users have the choice of PorteuX stable or its rolling release called current. See the install.txt for instructions on installing PorteuX to disk.

The CPU's translation lookaside buffer (TLB) caches the results of virtual-address translations, significantly speeding memory accesses. TLB misses are expensive, so a lot of thought goes into using the TLB as efficiently as possible. Reducing pressure on the TLB was the topic of Rik van Riel's memory-management-track session at the 2025 Linux Storage, Filesystem, Memory-Management, and BPF Summit. Some approaches were considered, but the session was short on firm conclusions.

For those of you who still have dedicated audio players: version 4.0 of Rockbox, a replacement firmware for many players, has been released. This release brings support for a number of new devices, updated codecs, a number of user-interface improvements, some new games, and more. (LWN last reviewed Rockbox in 2010 — and looked at the ill-fated Android port that year as well).

Security updates have been issued by Debian (firefox-esr, jetty9, openjpeg2, and tomcat9), Fedora (dokuwiki, firefox, php-kissifrot-php-ixr, php-phpseclib3, and rust-zincati), Red Hat (kernel and pki-core), Slackware (mozilla), SUSE (apparmor, atop, docker, docker-stable, firefox, govulncheck-vulndb, libmodsecurity3, openvpn, upx, and warewulf4), and Ubuntu (inspircd, linux, linux-aws, linux-gcp, linux-gke, linux-gkeop, linux-ibm, linux-lowlatency, linux-lowlatency-hwe-6.8, linux-oem-6.8, linux-oracle, linux-oracle-6.8, linux-aws, linux-aws-5.4, linux-aws-fips, linux-azure-6.8, linux-hwe-6.8, linux-raspi, linux-realtime, nginx, phpseclib, and vim).

The kernel's slab allocator is charged with providing small objects on demand; its performance and reliability are crucial for the functioning of the system as a whole. At the 2025 Linux Storage, Filesystem, Memory-Management, and BPF Summit, two adjacent sessions in the memory-management track dug into current work on the slab allocator. The first focused on the new sheaves feature, while the second discussed a set of allocation functions that are safe to call in any context.

From the LibreQoS site comes the sad news that Dave Täht has passed away. Among many other things, he bears a lot of credit for our networks functioning as well as they do. "We're incredibly grateful to have Dave as our friend, mentor, and as someone who continuously inspired us – showing us that we could do better for each other in the world, and leverage technology to make that happen. He will be dearly missed".

Searching through LWN's archives will turn up many references to his work fixing WiFi, improving queue management, tackling bufferbloat, and more. Farewell, Dave, we hope the music is good wherever you are.

(Thanks to Jon Masters for the heads-up).

As he has in some previous editions of the Linux Storage, Filesystem, Memory-Management, and BPF Summit (LSFMM+BPF), Fred Knight gave an update on the status of various storage standards this year. In it, he looked at changes to the NVM Express (NVMe) standards in some detail. He also updated attendees on the fairly small changes that have come to the SCSI (T10) and ATA (T13) standards over the last few years.

The kernel's kexec mechanism allows one kernel to directly boot a new one; it can be thought of as a sort of kernel equivalent to the execve() system call. Kexec has a number of uses, including booting a special kernel to perform dumps after a crash. Normally, one does not expect user-space processes to survive booting into a new kernel, but that has not stopped developers from trying to implement that ability. Mike Rapoport ran a memory-management-track session at the 2025 Linux Storage, Filesystem, Memory-Management, and BPF Summit to discuss one piece of that problem: enabling the contents of memory to persist across a kexec handover so that the new kernel can pick up where the old one left off.

Version 137.0 of the Firefox browser has been released. Changes include the rollout of tab groups, a number of search-bar changes, and the ability to add signatures to PDF files.

Security updates have been issued by AlmaLinux (freetype, grub2, kernel, kernel-rt, and python-jinja2), Debian (freetype, linux-6.1, suricata, tzdata, and varnish), Fedora (mingw-libxslt and qgis), Mageia (elfutils, mercurial, and zvbi), Oracle (grafana, kernel, libxslt, nginx:1.22, and postgresql:12), Red Hat (opentelemetry-collector), SUSE (corosync, opera, and restic), and Ubuntu (aom, libtar, mariadb, ovn, php7.4, php8.1, php8.3, rabbitmq-server, and webkit2gtk).

The virtual memory area (VMA), represented by struct vm_area_struct, is one of the core abstractions of the kernel's memory-management subsystem; a VMA represents a portion of a process's address space with the same characteristics. A memory-mapped file will be represented by (at least) one VMA, as will the process's stack or a region of anonymous memory. Efficiently managing VMAs and the logic around them is crucial for good performance overall. Lorenzo Stoakes focused on one specific problem area: the merging of anonymous VMAs, during the memory-management track at the 2025 Linux Storage, Filesystem, Memory-Management, and BPF Summit.

Migration is the act of moving data from one location in physical memory to another. The kernel may migrate pages for many reasons, including defragmentation, improving NUMA locality, moving data to or from memory hosted on a peripheral device, or freeing a range of memory for other uses. Given the importance of migration to the memory-management subsystem, there is a lot of interest in improving its performance and removing impediments to its success. Several sessions in the memory-management track of the 2025 Linux Storage, Filesystem, Memory-Management, and BPF Summit were dedicated to this topic.

The effort to ensure that open-source software is reproducible has been gathering steam over the years, and gaining traction with major Linux distributions. Debian, for example, has been working toward reproducible builds for more than a decade; it can now produce official live CDs of the current stable release that are reproducible. Fedora started on the path much later, but it has progressed far enough that the project is now considering a change proposal for the Fedora 43 development cycle, expected to be released in October, with a goal of making 99% of Fedora's package builds reproducible. So far, reaction to the proposal seems favorable and focused primarily on how to achieve the goal—with minimal pain for packagers—rather than whether to attempt it.

Security updates have been issued by Debian (amd64-microcode, flatpak, intel-microcode, libdata-entropy-perl, librabbitmq, and vim), Fedora (augeas, containerd, crosswords-puzzle-sets-xword-dl, libssh2, libxml2, nodejs-nodemon, and webkitgtk), Red Hat (libreoffice and python-jinja2), SUSE (389-ds, apparmor, corosync, docker, docker-stable, erlang26, exim, ffmpeg-4, govulncheck-vulndb, istioctl, matrix-synapse, mercurial, openvpn, python3, rke2, and skopeo), and Ubuntu (ansible, linux, linux-hwe-5.4, linux-azure, linux-azure-5.4, linux-bluefield, linux-gcp, linux-gcp-5.4, linux-ibm, linux-kvm, linux-oracle, linux-oracle-5.4, linux-xilinx-zynqmp, linux-azure-fips, linux-gcp-fips, linux-fips, linux-fips, linux-aws-fips, linux-azure-fips, linux-gcp-fips, linux-nvidia-tegra, linux-nvidia-tegra-igx, linux-realtime, linux-intel-iot-realtime, linux-xilinx-zynqmp, opensc, and ruby-doorkeeper).

Greg Kroah-Hartman announced the release of four stable kernels on March 28: 6.13.9, 6.12.21, 6.6.85, and 6.1.132. Users are advised to upgrade.

KDE contributor David Edmundson has published a blog post about improving KDE Plasma's login experience by replacing SDDM with a new Plasma Login Manager.

It's worth stressing nothing is official or set in stone yet, whilst it has come up in previous Plasma online meetings and in the 2023 Akademy. I'm posting this whilst starting a more official discussion on the plasma-devel mailing list.

Oliver Beard and I have made a new mutli-process greeter, that uses the same startup mechanism as the desktop session. It doesn't have all the features that we propose at the start of the blog, but an architecture where features and services can be slowly and safely added.

That discussion is here for those who would like to follow along. The prototype is currently in two repositories: plasma-login for the frontend work, and plasma-login-manager, which is a fork of SDDM.