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[$] Supporting BPF in GCC
The GCC project has been working to support compiling to BPF for some time. José Marchesi and David Faust spoke in an extended session at the 2024 Linux Storage, Filesystem, Memory Management, and BPF Summit about how that work has been going, and what is left for GCC to be on-par with LLVM with regard to BPF support. They also related tentative plans for how GCC BPF support would be maintained in the future.
[$] Filesystems and iomap
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.
[$] Measuring memory fragmentation
In the final session in the memory-management track of the 2024 Linux Storage, Filesystem, Memory-Management and BPF Summit, the exhausted group of developers looked one more time at the use of huge pages and the associated problem of memory fragmentation. At its worst, this problem can make huge pages harder (and more expensive) to allocate. Luis Chamberlain, who ran the session, felt that people were worried about this problem, but that there was little data on how severe it truly is.
[$] The state of the memory-management community in 2024
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.
[$] LLVM improvements for BPF verification
Alan Jowett gave a remote presentation at the 2024 Linux Storage, Filesystem, Memory Management, and BPF Summit about what features could be added to LLVM to make writing BPF programs easier. While there is nothing specific to LLVM about BPF code (and the next session in the track was led by GCC developer José Marchesi about better support for that compiler), LLVM is currently the most common way to turn C code into BPF bytecode. That translation, however, runs into problems when the BPF verifier cannot understand the code LLVM's optimizations produce.
[$] Fleshing out memory descriptors
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.
[$] The rest of the 6.10 merge window
Linus Torvalds released 6.10-rc1 and closed the 6.10 merge window on May 26. By that time, 11,534 non-merge changesets had been pulled into the mainline for the next release; nearly 5,000 of those came in after "The first half of the 6.10 merge window" was written. While the latter half of the merge window tends to focus more on fixes, there was also a lot of new functionality that landed during this time.
[$] The next steps for the maple tree
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.
[$] Two talks on multi-size transparent huge page performance
Using huge pages has been known for years to improve the performance of many workloads. But traditional huge pages, often sized by the CPU at 2MB, can be difficult to allocate and can waste memory due to internal fragmentation. Driven by both the folio transition and hardware improvements, attention to smaller, multi-size transparent huge pages (mTHPs) has been on the rise. In two memory-management-track sessions at the 2024 Linux Storage, Filesystem, Memory-Management and BPF Summit, developers discussed the kernel's ability to reliably allocate mTHPs and the performance gains that result.
[$] Atomic writes without tears
John Garry and Ted Ts'o led a discussion about supporting atomic writes for buffered I/O, without any torn (or partial) writes to the device, at the 2024 Linux Storage, Filesystem, Memory Management, and BPF Summit. It is something of a continuation of a discussion at last year's summit. The goal is to help PostgreSQL, which writes its data using 16KB buffered I/O; it currently has to do a lot of extra work to ensure that its data is safe on disk. A promise of non-torn, 16KB buffered writes would allow the database to avoid doing double writes.
Security updates for Tuesday
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).
Huston: Calling Time on DNSSEC?
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.
Security updates for Monday
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).
Kernel prepatch 6.10-rc1
Linus has released 6.10-rc1 and closed the merge window for this release. For reasons that have not been spelled out, the codename for the release has been changed to "Baby Opossum Posse".
Eight weekend stable kernel updates
The 6.9.2, 6.8.11, 6.6.32, 6.1.92, 5.15.160, 5.10.218, 5.4.277, and 4.19.315 stable kernel updates have all been released. Each contains an important set of fixes. Users of those kernels should upgrade.
BitKeeper, Linux, and licensing disputes: How Linus wrote Git in 14 days (Graphite blog)
This Graphite blog post retells the history of the BitKeeper fiasco and the dawn of the Git era.
When we think of history, we often romanticize it as being born of a sudden stroke of inspiration. But the creation of git shows the far harsher reality of invention: a slowly escalating disagreement over a license; the need for a scrappy backup solution to unblock work; and then continued polishing and iteration through years and years, led not by the inventor, but rather a community.
For those who weren't around in those days, a perusal of the LWN coverage from the time might be of interest too, including:
- Our first mention of BitKeeper in October 1998
- Not quite open source, 1999
- Linus tries out BitKeeper, 2002
- The free software community and proprietary packages, 2002
- The kernel and BitKeeper part ways, 2005
- How Tridge reverse engineered BitKeeper, 2005
- The guts of Git, 2005
...and a lot more for those who care to search for it.
Security updates for Friday
Security updates have been issued by Fedora (chromium, libreoffice, and thunderbird), Red Hat (.NET 7.0, .NET 8.0, gdk-pixbuf2, git-lfs, glibc, python3, and xorg-x11-server-Xwayland), SUSE (firefox, opensc, and ucode-intel), and Ubuntu (cjson and gnome-remote-desktop).
KDE Gear 24.05.0
The KDE Project has announced the release of KDE Gear 24.05.0, with new features and updates for the more than 200 applications that are part of the project. In addition to new versions of the Dolphin file manager, Kdenlive video editor, and Elisa music player, this release includes five applications new to KDE Gear: the Audex CD-ripper application, an application Accessibility Inspector, the Francis Pomodoro timer, Kalm to teach breathing techniques, and a Sokoban-like game called Skladnik. See the full changelog for a complete list of changes.
Security updates for Thursday
Security updates have been issued by Debian (chromium), Fedora (chromium, libxml2, pgadmin4, and python-libgravatar), Mageia (ghostscript), Red Hat (389-ds:1.4, ansible-core, bind and dhcp, container-tools:rhel8, edk2, exempi, fence-agents, freeglut, frr, ghostscript, glibc, gmp, go-toolset:rhel8, grafana, grub2, gstreamer1-plugins-bad-free, gstreamer1-plugins-base, gstreamer1-plugins-good, harfbuzz, httpd:2.4, idm:DL1, idm:DL1 and idm:client modules, kernel, kernel-rt, krb5, LibRaw, libreoffice, libsndfile, libssh, libtiff, libX11, libxml2, libXpm, linux-firmware, motif, mutt, openssh, osbuild and osbuild-composer, pam, pcp, pcs, perl-Convert-ASN1, perl-CPAN, perl:5.32, pki-core:10.6 and pki-deps:10.6 modules, pmix, poppler, postgresql-jdbc, python-dns, python-jinja2, python-pillow, python27:2.7, python3.11, python3.11-cryptography, python3.11-urllib3, python39:3.9 and python39-devel:3.9 modules, qt5-qtbase, resource-agents, squashfs-tools, sssd, systemd, tigervnc, tomcat, traceroute, varnish:6, virt:rhel and virt-devel:rhel modules, vorbis-tools, webkit2gtk3, xorg-x11-server, xorg-x11-server-Xwayland, and zziplib), SUSE (chromium, perl, postgresql14, and python-sqlparse), and Ubuntu (klibc, linux-aws-hwe, openssl, and vlc).
Alpine Linux 3.20.0 released
Version 3.20.0 of the Alpine Linux distribution has been released with initial support for 64-bit RISC-V. Other important changes include updates to GNOME 46, KDE Plasma 6, and replacing Redis with Valkey due to Redis's adoption of a non-free license model. See the release notes for more on this release.