Linux Weekly News

While BPF may be most famous for its use in the Linux kernel, there is actually a growing effort to standardize BPF for use on other systems. These include eBPF for Windows, but also uBPF, rBPF, hBPF, bpftime, and others. Some hardware manufacturers are even considering integrating BPF directly into networking hardware. Dave Thaler led two sessions about all of the problems that cross-platform use inevitably brings and the current status of the standardization work at the 2024 Linux Storage, Filesystem, Memory Management, and BPF Summit.

A discussion of extensions to the statx() system call comes up frequently at the Linux Storage, Filesystem, Memory Management, and BPF Summit; this year's edition was no exception. Kent Overstreet led the first filesystem-only session at the summit on querying information about filesystems that have subvolumes and snapshots. While it was billed as a discussion on statx() additions, it ranged more widely over new APIs needed for modern filesystems.

Greg Kroah-Hartman has announced the release of the 6.9.3 and 6.8.12 stable kernels. As usual, they contain lots of important fixes throughout the tree. Note that 6.8.12 is the end of the line for the 6.8.x stable kernel series.

Security updates have been issued by Debian (python-pymysql), Fedora (chromium, mingw-python-requests, and thunderbird), Mageia (perl-Email-MIME and qtnetworkauth5 & qtnetworkauth6), Red Hat (gdisk and python39:3.9 and python39-devel:3.9 modules), SUSE (freerdp, gdk-pixbuf, gifsicle, glib2, java-1_8_0-ibm, kernel, libfastjson, libredwg, nodejs16, python, python3, python36, rpm, warewulf4, and xdg-desktop-portal), and Ubuntu (gst-plugins-base1.0, python-werkzeug, and tpm2-tss).

The LWN.net Weekly Edition for May 30, 2024 is available.

The Asahi Linux project works to support Linux on Apple Silicon hardware. The project's flagship distribution is the Fedora Asahi Remix, which has its own installer (rather than Anaconda) to accommodate the unique requirements of installing on Apple's hardware. Previously the installer was built by the Asahi project, but it has asked for (and received) an exception from the Fedora Engineering Steering Committee (FESCo) to include two binaries from upstream open-source projects so that the installer can be built on Fedora infrastructure.

The FreeBSD Foundation has announced the 2024 FreeBSD Community Survey Report. The report provides a summary of 1,446 responses to an anonymous online survey of FreeBSD users. It provides insights into user profiles, typical usage, how the FreeBSD project is viewed, as well as recommendations for expanding the FreeBSD community and contributor base:

Currently fewer than half of users consider FreeBSD their daily driver; Individuals are less likely than Corporate Users to consider FreeBSD primary. The barrier seems to be less about software and more about hardware support, particularly around Wi-Fi drivers (which are at the top of the wish list for the Foundation to focus on in the coming year). A relatively high number of those who don't consider FreeBSD their main OS say they would consider doing so with hardware support for desktops and laptops that was equivalent to Linux.

The raw data for the survey is available as well.

When redesigning the LWN site in 2002, we thought long and hard about whether the ability to post comments should be part of it; LWN had not offered that feature for the first four years of its existence. There were already plenty of examples of how comments can go bad by then, but we decided to trust our readers to keep things under control. Much of the time, that trust has proved justified, but there have been times where things have not gone so well. This time is quickly becoming one of those others.

Security updates have been issued by AlmaLinux (glibc and tomcat), Fedora (chromium, fcitx5-qt, python-pyqt6, qadwaitadecorations, qgnomeplatform, qt6, qt6-qt3d, qt6-qt5compat, qt6-qtbase, qt6-qtcharts, qt6-qtcoap, qt6-qtconnectivity, qt6-qtdatavis3d, qt6-qtdeclarative, qt6-qtgraphs, qt6-qtgrpc, qt6-qthttpserver, qt6-qtimageformats, qt6-qtlanguageserver, qt6-qtlocation, qt6-qtlottie, qt6-qtmqtt, qt6-qtmultimedia, qt6-qtnetworkauth, qt6-qtopcua, qt6-qtpositioning, qt6-qtquick3d, qt6-qtquick3dphysics, qt6-qtquicktimeline, qt6-qtremoteobjects, qt6-qtscxml, qt6-qtsensors, qt6-qtserialbus, qt6-qtserialport, qt6-qtshadertools, qt6-qtspeech, qt6-qtsvg, qt6-qttools, qt6-qttranslations, qt6-qtvirtualkeyboard, qt6-qtwayland, qt6-qtwebchannel, qt6-qtwebengine, qt6-qtwebsockets, qt6-qtwebview, and zeal), Red Hat (glibc, kernel, kernel-rt, kpatch-patch, linux-firmware, mod_http2, pcp, pcs, protobuf, python3, rpm-ostree, and rust), SUSE (git, glibc-livepatches, kernel, libxml2, openssl-1_1, SUSE Manager Client Tools, SUSE Manager Client Tools, salt, and xdg-desktop-portal), and Ubuntu (amavisd-new, firefox, flask-security, frr, git, intel-microcode, jinja2, libreoffice, linux-intel-iotg, unbound, and webkit2gtk).

The GCC project has been working to support compiling to BPF for some time. José Marchesi and David Faust spoke in an extended session at the 2024 Linux Storage, Filesystem, Memory Management, and BPF Summit about how that work has been going, and what is left for GCC to be on-par with LLVM with regard to BPF support. They also related tentative plans for how GCC BPF support would be maintained in the future.

The iomap block-mapping abstraction is being used by more filesystems, in part because of its support for large folios. But there are some challenges in adopting iomap, which was the topic of a discussion led by Ritesh Harjani in a combined storage and filesystem session at the 2024 Linux Storage, Filesystem, Memory Management, and BPF Summit. One of the main trouble spots is how to handle metadata, which is not an area that iomap has been aimed at.

In the final session in the memory-management track of the 2024 Linux Storage, Filesystem, Memory-Management and BPF Summit, the exhausted group of developers looked one more time at the use of huge pages and the associated problem of memory fragmentation. At its worst, this problem can make huge pages harder (and more expensive) to allocate. Luis Chamberlain, who ran the session, felt that people were worried about this problem, but that there was little data on how severe it truly is.

A longstanding tradition in the memory-management track of the Linux Storage, Filesystem, Memory-Management and BPF Summit is a session with maintainer Andrew Morton to discuss the overall state of the community and the development process. The 2024 gathering upheld that tradition toward the end of the final day of the event. It seems that Morton and the assembled developers were all happy with how memory-management work is going, but there is always room for improvement.

Security updates have been issued by Debian (less), Mageia (chromium-browser-stable), SUSE (apache2, java-1_8_0-openj9, kernel, libqt5-qtnetworkauth, and openssl-3), and Ubuntu (netatalk and python-cryptography).

Geoff Huston suggests that it is time to give up on DNSSEC and look for a better way to secure the Internet namespace.

What appears to be very clear (to me at any rate!) is that DNSSEC as we know it today is just not going anywhere. It's too complex, too fragile and just too slow to use for the majority of services and their users. Some value its benefits highly enough that they are prepared to live with its shortcomings, but that's not the case for the overall majority of name holders and for the majority of users, and no amount of passionate exhortations about DNSSEC will change this.

Alan Jowett gave a remote presentation at the 2024 Linux Storage, Filesystem, Memory Management, and BPF Summit about what features could be added to LLVM to make writing BPF programs easier. While there is nothing specific to LLVM about BPF code (and the next session in the track was led by GCC developer José Marchesi about better support for that compiler), LLVM is currently the most common way to turn C code into BPF bytecode. That translation, however, runs into problems when the BPF verifier cannot understand the code LLVM's optimizations produce.

One of the long-term goals of the folio conversion in the kernel's memory-management subsystem is the replacement of the page structure, which describes a page of physical memory, with an eight-byte "memory descriptor". This change would reduce the overhead of tracking physical memory, increase type safety, and make memory management more flexible. Thus far, though, details on what the memory-descriptor future will look like have been relatively scarce. At the 2024 Linux Storage, Filesystem, Memory-Management and BPF Summit, Matthew Wilcox led a discussion to try to fill in the picture somewhat.

Security updates have been issued by Debian (apache2, bluez, chromium, fossil, libreoffice, python-pymysql, redmine, and ruby-rack), Fedora (buildah, crosswords, dotnet7.0, glycin-loaders, gnome-tour, helix, helvum, libipuz, loupe, maturin, mingw-libxml2, ntpd-rs, perl-Email-MIME, and a huge list of Rust-based packages due to a "mini-mass-rebuild" that updated the toolchain to Rust 1.78 and picked up fixes for various pieces), Mageia (chromium-browser-stable, mariadb, and roundcubemail), Oracle (kernel, libreoffice, nodejs, and tomcat), and SUSE (cJSON, libfastjson, opera, postgresql15, python3, and qt6-networkauth).

Linus Torvalds released 6.10-rc1 and closed the 6.10 merge window on May 26. By that time, 11,534 non-merge changesets had been pulled into the mainline for the next release; nearly 5,000 of those came in after "The first half of the 6.10 merge window" was written. While the latter half of the merge window tends to focus more on fixes, there was also a lot of new functionality that landed during this time.

The maple tree data structure was added during the 6.1 development cycle; since then, it has taken its place at the core of the kernel's memory-management subsystem. Unsurprisingly, work on maple trees is not yet done. Maple-tree maintainer Liam Howlett ran a session in the memory-management track of the 2024 Linux Storage, Filesystem, Memory-Management and BPF Summit to discuss the current state of the maple tree and which features can be expected next.