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Two Google engineers came to Open Source Summit North America 2021 to talk about a project to change the way the company creates and maintains the kernel it runs in its data centers on its production systems. Andrew Delgadillo and Dylan Hatch described the current production kernel (Prodkernel) and the problems that occur because it is so far from the mainline. Project Icebreaker is an effort to change that and to provide a near-mainline kernel for development and testing within Google; the talk looked at the project, its risks, its current status, and its plans.
Julia is an open-source programming language and ecosystem for high-performance scientific computing; its development team has made the first release candidate for version 1.7 available for testing on Linux, BSD, macOS, and Windows. Back in May, we looked at the increased performance that arrived with Julia 1.6, its last major release. In this article we describe some of the changes and new features in the language and its libraries that are coming in 1.7.
Developers working in languages like C or C++ have access to two competing compilers — GCC and LLVM — either of which can usually get the job done. Rust developers, though, are currently limited to the LLVM-based rustc compiler. While rustc works well, there are legitimate reasons for developers to wish for an alternative. As it turns out, there are two different ways to compile Rust using GCC under development, though neither is ready at the moment. Developers of both approaches came to the 2021 Linux Plumbers Conference to present the status of their work.
Much of the free-software development world has adopted Git forges (such as GitHub, GitLab, or sourcehut) with enthusiasm. The kernel community has not. Reasons for that reticence vary, but one that is often heard is that these forges simply don't work well at the scale needed for the kernel project. At a Kernel-Summit session during the 2021 Linux Plumbers conference, Donald Zickus and Prarit Bhargava sought to show how Red Hat has put GitLab to good use to support its kernel team. Not only can these forges work for kernel development, they said, but moving to a forge can bring a number of advantages.
The term "interrupt" brings to mind a signal that originates in the hardware and which is handled in the kernel; even software interrupts are a kernel concept. But there is, it seems, a use case for enabling user-space processes to send interrupts directly to each other. An upcoming Intel processor generation includes support for this capability; at the 2021 Linux Plumbers Conference, Sohil Mehta ran a Kernel-Summit session on how Linux might support that feature.
The LWN.net Weekly Edition for September 30, 2021 is available.
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Work toward the signing of BPF programs has been finding its way into recent mainline kernel releases; it is intended to improve security by limiting the BPF programs that can be successfully loaded into the kernel. As John Fastabend described in his "Watching the super powers" session at the 2021 Linux Plumbers Conference, this new feature has the potential to completely break his tools. But rather than just complain, he decided to investigate solutions; the result is an outline for an auditing mechanism that brings greater flexibility to the problem of controlling which programs can be run.
A controversy about the handling of the Time Zone Database (tzdb) has been brewing since May, but has come to a head in recent weeks. Changes that were proposed to simplify the main database file have some consequences in terms of time-zone history and changes to the representation of some zones. Those changes have upset a number of users of the database—to the point where some have called for a fork. A September 25 release of tzdb with some, but not all, of the changes seems unlikely to resolve the conflict.
The Kernel Maintainers Summit is an invitation-only gathering of top-level kernel subsystem maintainers; it is concerned mostly with process-oriented issues that are not easily worked out on the mailing lists. There was no maintainers summit in 2020; plans had been made to hold it in an electronic form, but there turned out to be a lack of things to talk about. In 2021, though, a number of interesting topics turned up, so an online gathering was held on September 24 as part of the Linux Plumbers Conference.
Read on for a summary of the discussions held at this year's Summit.
It has often been said that the competition between the GCC and LLVM compilers is good for both of them. One place where that competition shows up is in the area of security features; if one compiler adds a way to harden programs, the other is likely to follow suit. Qing Zhao's session at the 2021 Linux Plumbers Conference told the story of how GCC successfully played catch-up for two security-related features that were of special interest to the kernel community.
The Asahi Linux project has a progress report on its goal of running Linux on Mac M1 hardware.
Earlier this year we saw the absolute lowest level drivers being merged into the kernel. Those are important for bring-up, but to get a usable system we need many more. Over September we’ve seen a lot of action on this front, with many important drivers now in review or even already merged for Linux 5.16. The goal of the Asahi Linux project is to upstream everything into the Linux kernel, so all our drivers are eventually headed for upstream review.
The AlmaLinux Foundation has opened membership to everyone.
The AlmaLinux Foundation [...] was created as a 501(c)(6) non-profit (the same as the Linux Foundation) in order to put OWNERSHIP of the OS, the Intellectual Property and the direction of the project into the hands of the community. By joining as a member (100% free for community members) you have the right and the ability to vote on board members and the direction of the project and other decisions as they will come up in the future.
Firefox 93.0 has been released. With this version Firefox supports the new AVIF image format, which is based on the modern and royalty free AV1 video codec. The PDF viewer supports filling more forms, such as XFA-based forms used by multiple governments and banks. Downloads that rely on insecure connections are blocked, protecting against potentially malicious or unsafe downloads. Details on these features and more can be found in the release notes.
Version 13.0.0 of the LLVM compiler suite is out. There is a long list of changes, as always; see the numerous sets of release notes below for details.
Security updates have been issued by Fedora (cryptopp), Mageia (kernel, kernel-linus, and sqlite), openSUSE (rabbitmq-server), Red Hat (kernel and samba), SUSE (glibc and webkit2gtk3), and Ubuntu (containerd, docker.io, imlib2, ledgersmb, mercurial, mongodb, and node-bl).
Version 3.10.0 of the Python language has been released. There are a lot of significant changes in this release, including the much-discussed structural pattern-matching feature. See this article for an overview of what's in 3.10.
Security updates have been issued by Debian (apache2, fig2dev, mediawiki, plib, and qemu), Fedora (chromium, curl, kernel, kernel-headers, kernel-tools, openssh, rust-addr2line, rust-backtrace, rust-cranelift-bforest, rust-cranelift-codegen, rust-cranelift-codegen-meta, rust-cranelift-codegen-shared, rust-cranelift-entity, rust-cranelift-frontend, rust-cranelift-native, rust-cranelift-wasm, rust-gimli, rust-object, rust-wasmparser, rust-wasmtime-cache, rust-wasmtime-environ, rust-wasmtime-fiber, rust-wasmtime-types, rust-wast, rust-wat, and webkit2gtk3), Mageia (apache-mod_auth_openidc, c-ares, chromium-browser-stable, icu, libspf2, perl-DBI, python, and python-rsa), openSUSE (haproxy and opera), Oracle (kernel), SUSE (firefox and libvirt), and Ubuntu (python3.8).
The 5.15-rc4 kernel prepatch is out for testing.
One thing standing out in the diffs might be the m68k 'set_fs()' removal - not really a regression fix, but it has been pending for a while, and it turned out that the problems attributed to it were due to an entirely unrelated m68k signal handling issue. So with that fixed, we could get rid of set_fs from another architecture.
See this article for information on set_fs() and its removal.
Paul McKenney has started a blog series on Rust for the Linux kernel. He has posted six of a planned 11 articles, though several are labeled as "under construction".
This series focuses mostly on use cases and opportunities, rather than on any non-trivial solutions. Please note that I am not in any way attempting to dictate or limit Rust's level of ambition. I am instead noting the memory-model consequences of a few potential levels of ambition, ranging from "portions of a few drivers", "a few drivers", "some core code" and up to and including "the entire kernel". Greater levels of ambition will require greater willingness to accommodate a wider variety of LKMM [Linux-kernel memory model] requirements.[...] These blog posts will therefore present approaches ranging upwards from trivial workarounds. But be warned that some of the high-quality approaches require profound reworking of compiler backends that have thus far failed to spark joy in the hearts of compiler writers. In addition, Rust enjoys considerable use outside of the Linux kernel, for example, as something into which to rewrite inefficient Python scripts. (A megawatt here, a megawatt there, and pretty soon you are talking about real power consumption!) Therefore, there are probably sharp limits beyond which the core Rust developers are unwilling to go.
Security updates have been issued by Debian (curl, krb5, openssl1.0, and taglib), Fedora (cifs-utils), SUSE (libqt5-qtbase and rubygem-activerecord-4_2), and Ubuntu (linux-raspi, linux-raspi-5.4 and linux-raspi2).
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