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Lossless data compression is an important tool for reducing the storage requirements of the world's ever-growing data sets. Yann Collet developed the LZ4 algorithm and designed the Zstandard (or Zstd) algorithm; he came to the 2025 Open Source Summit Japan in Tokyo to talk about where data compression goes from here. It turns out that we have reached a point where general-purpose algorithms are only going to provide limited improvement; for significant increases in compression, while keeping computation costs within reason for data-center use, turning to format-specific techniques will be needed.

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The Debian GNOME team would like to remove the GTK 2 graphics toolkit, which has been unmaintained upstream for more than five years, and ship Debian 14 ("forky") without it. As one might expect, however, there are those who would like to find a way to keep it. Despite its age and declared obsolescence, quite a few Debian packages still depend on GTK 2. Many of those applications are unlikely to be updated, and users are not eager to give them up. Discussion about how to handle this is ongoing; it seems likely that Debian developers will find some way to continue supporting applications that require GTK 2, but users may have to look outside official Debian repositories.

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Quality-of-service (QoS) mechanisms attempt to prioritize some processes (or network traffic, disk I/O, etc.) over others in order to meet a system's performance goals. This is a difficult topic to handle in the world of Linux, where workloads, hardware, and user expectations vary wildly. Qais Yousef spoke at the 2025 Linux Plumbers Conference, alongside his collaborators John Stultz, Steven Rostedt, and Vincent Guittot, about their plans for introducing a high-level QoS API for Linux in a way that leaves end users in control of its configuration. The talk focused specifically on a QoS mechanism for the scheduler, to prioritize access to CPU resources differently for different kinds of processes. (slides; video)

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In open-source circles there are many situations, such as bug reports, demos, and tutorials, when one might want to provide a play-by-play of a session in one's terminal. The asciinema project provides a set of tools to do just that. Its tools let users record, edit, and share terminal sessions in a text-based format that has quite a few advantages compared to making and sharing videos of terminal sessions. For example, it is easy to use, offers the ability to search text from recorded sessions, and allows users to copy and paste directly from the recording.

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The READ_ONCE() and WRITE_ONCE() macros are heavily used within the kernel; there are nearly 8,000 call sites for READ_ONCE(). They are key to the implementation of many lockless algorithms and can be necessary for some types of device-memory access. So one might think that, as the amount of Rust code in the kernel increases, there would be a place for Rust versions of these macros as well. The truth of the matter, though, is that the Rust community seems to want to take a different approach to concurrent data access.

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The Software Freedom Conservancy (SFC) is suing VIZIO over smart TVs that include software licensed under the GPL and LGPL (including the Linux kernel, FFmpeg, systemd, and others). VIZIO didn't provide the source code along with the device, and on request they only provided some of it. Unlike a typical lawsuit about enforcing the GPL, the SFC isn't suing as a copyright holder; it's suing as a normal owner of the TV in question. This approach opens some important legal questions, and after years of pre-trial maneuvering (most recently resulting in a ruling related to signing keys that is the subject of a separate article), we might finally obtain some answers when the case goes to trial on January 12. As things stand, it seems likely that the judge in the case will rule that that the GPL-enforcement lawsuits can be a matter of contract law, not just copyright law, which would be a major change to how GPL enforcement works.

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On December 24 2025, Linus Torvalds posted a strongly worded message celebrating a ruling in the ongoing GPL-compliance lawsuit filed against VIZIO by the Software Freedom Conservancy (SFC). This case and Torvalds's response have put a spotlight on an old debate over the extent to which the source-code requirements of the GNU General Public License (version 2) extend to keys and other data needed to successfully install modified software on a device. It is worth looking at whether this requirement exists, the subtleties in interpretation that cloud the issue, and the extent to which, if any, the SFC is demanding that information.

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At the 2025 Linux Plumbers Conference (LPC), held in Tokyo in mid-December, Changwoo Min led a session on what he has learned while developing the "latency-criticality aware virtual deadline" (LAVD) scheduler, which is aimed at gaming workloads. The session was part of the Gaming on Linux microconference, which is a new entrant into LPC; organizers hope to see it return next year in Prague and, presumably, beyond. LAVD uses the extensible scheduler class (sched_ext) and has the primary goal of minimizing stuttering in games; it is implemented in a combination of BPF and Rust.

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Last year we revived the tradition of publishing a timeline of notable events from the previous year. Since that seemed to go over well, we decided we should continue the practice and look back on some of the most noteworthy events and releases of 2025.

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