LWN on Kernel, Fedora and GPG 2.5, and postmarketOS

posted by Roy Schestowitz on Feb 05, 2026

• Kernel Space / File Systems / Virtualization

  • LWN ☛ Linux Kernel Runtime Guard reaches its 1.0 release

    The Linux Kernel Runtime Guard (LKRG) is a out-of-tree loadable kernel module that attempts to detect and report violations of the kernel's internal invariants, such as might be caused by an in-progress security exploit or a rootkit. LKRG has been experimental since its initial release in 2018. In September 2025, the project announced the 1.0 version. With the promises of stability that version brings, users might want more information to decide whether to include it in their kernel.

    Security through diversity

    LKRG's mission is mildly hopeless — if an attacker has already compromised a running kernel, then there is no theoretical reason that the attacker could not also recognize and block or subvert the LKRG kernel module. In practice, however, an attacker would need to actually know to do that, and do it quickly enough to escape the periodic sweeps that LKRG performs. Using LKRG, therefore, raises the bar for attacks on the Linux kernel.

  • LWN ☛ Filesystem medley: EROFS, NTFS, and XFS

    Filesystems seem to be one of those many areas where the problems are well understood, but there is always somebody working toward a better solution. As a result, filesystem development in the Linux kernel continues at a fast pace even after all these years. In recent news, the EROFS filesystem is on the path to gain a useful page-cache-sharing feature, there is a new NTFS implementation on the horizon, and XFS may be about to get an infrastructure for self healing.

  • LWN ☛ Implicit arguments for BPF kfuncs

    The kernel's "kfunc" mechanism is a way of exporting kernel functions so that they can be called directly from BPF programs. There are over 300 kfuncs in current kernels, ranging in functionality from string processing (bpf_strnlen()) to custom schedulers (scx_bpf_kick_cpu()) and beyond. Sometimes these kfuncs need access to context information that is not directly available to BPF programs, and which thus cannot be passed in as arguments. The implicit arguments patch set from Ihor Solodrai is the latest attempt to solve this problem.

    The BPF subsystem maintains a collection of context information in the massive bpf_prog_aux structure. Over the years it has grown to contain just about any sort of information that may be needed, including a list of maps the program is using, how long since it was loaded, the current stack depth, and dozens of other fields. It can almost be thought of as an analog to the self object passed to methods in some object-oriented languages. A number of kfuncs need to make use of this structure, but it is not something that BPF programs themselves can access.

• Distributions and Operating Systems

  • Fedora Family / IBM

    • LWN ☛ Fedora and GPG 2.5

      The GNU Privacy Guard (GPG) project decided to break from the OpenPGP standard for email encryption in 2023, and instead adopted its own homegrown LibrePGP specification. The GPG 2.4 branch, the last one to adhere to OpenPGP, will be reaching the end of life in mid-2026. The Fedora project is currently having a discussion about how that affects the distribution, its users, and what to offer once 2.4 is no longer receiving updates.

  • Mobile Systems/Mobile Applications

    • LWN ☛ Open source for phones: postmarketOS [LWN.net]

      Phones running Linux are ubiquitous these days and it has been that way since Android started working toward dominance in the smartphone market. Unfortunately, Android has slowly increased its freedom-unfriendliness and has become something of a privacy nightmare. In a talk entitled "We need an open-source phone OS" at Open Source Summit Japan 2025, Luca Weiss described the smartphone landscape and gave an overview of postmarketOS as an alternative Linux operating system for mobile handsets.

      Weiss introduced himself as a software engineer at Fairphone, ""which is a Dutch brand to make sustainable mobile phones"". In his free time, he is a postmarketOS core contributor and a maintainer for the OpenRazer project to create Linux drivers for Razer gaming peripherals. He stressed that the talk was not being done for his employer; ""these are my opinions"".