IBM Looking for Volunteer Kernel Testers, LWN's Latest Kernel Articles Outside Paywall
-
Fedora Magazine: Contribute at the Fedora Linux Test Week for Kernel 6.3
The kernel team is working on final integration for Linux kernel 6.3. This version was just recently released, and will arrive soon in Fedora Linux. As a result, the Fedora Linux kernel and QA teams have organized a test week from Sunday, May 07, 2023 to Sunday, May 14, 2023. Refer to the wiki page in this article for links to the test images you’ll need to participate. Please continue reading for details.
-
Disabling SELinux's runtime disable
Distributors have been enabling the SELinux security module for nearly 20 years now, and many administrators have been disabling it on their systems for almost as long. There are a few ways in which SELinux can be disabled on any given system, including command-line options, a run-time switch, or simply not loading a policy after boot. One of those ways, however, is about to be disabled itself.
SELinux undoubtedly improves the security of a system; it can confine processes to the resources that they are intended to use. But SELinux can also get in the way, especially in situations where some program does not behave in the way that the policy authors expected. The tools for figuring out where a problem lies and amending SELinux policies have improved over the years but, for many, convincing SELinux to let some task proceed is simply not worth the trouble. These are the people who end up just turning it off altogether.
The kernel provides a set of options for doing that, beyond building a kernel that does not include SELinux at all. The selinux=0 command-line parameter will disable SELinux at boot. Another option is editing /etc/selinux/config, which can have the effect of preventing an SELinux policy from being loaded into the kernel. Without a policy, SELinux deems itself to be in an uninitialized state and will not enforce any restrictions. Finally, writing a zero to /sys/fs/selinux/disable will disable SELinux until the next boot, but only if no policy has yet been loaded.
-
Designated movable (memory) blocks
The concept of movable memory was initially designed for hot-pluggable memory on server-class systems, but it would now appear that this mechanism is finding a new use in consumer-electronics devices as well. The designated movable block patch set was first submitted by Doug Berger in September 2022. By adding more flexibility around the configuration and use of movable memory, this work will, it is hoped, improve how Linux performs on resource-constrained systems.
The motivation for these patches stems from the need to support large, contiguous allocations (2MB or more) for audio and video device drivers on hardware that lacks an IOMMU and may have a small amount (1-2GB) of memory. These devices are commonly found as set-top boxes running a variety of Linux-based software environments from RDK and Android TV to entirely custom software stacks.
-
Development statistics for 6.3
The 6.3 kernel was released on April 24 after a nine-week development cycle. As is the case with all mainline releases, this is a major kernel release with a lot of changes and a big pile of new features. The time has come, yet again, for a look at where that work came from and who supported it.
The 6.3 development cycle saw the merging of 14,424 non-merge changesets from 1,971 developers, which is a bit of a slowdown from 6.2. Of those developers, 250 made their first kernel contribution for this release. The work merged for 6.2 deleted over 513,000 lines of code — far more than the usual — but the kernel still grew by over 131,000 lines.