LWN's Latest Articles About Linux (Kernel)
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Linus and Dirk chat about AI, XZ, hardware, and more
One of the mainstays of the Linux Foundation's Open Source Summit is the "fireside chat" (sans fire) between Linus Torvalds and Dirk Hohndel to discuss open source and Linux kernel topics of the day. On April 17, at Open Source Summit North America (OSSNA) in Seattle, Washington, they held with tradition and discussed a range of topics including proper whitespace parsing, security, and the current AI craze.
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Warning about WARN_ON()
Kernel developers, like conscientious developers for many projects, will often include checks in the code for conditions that are never expected to occur, but which would indicate a serious problem should that expectation turn out to be incorrect. For years, developers have been encouraged (to put it politely) to avoid using assertions that crash the machine for such conditions unless there is truly no alternative. Increasingly, though, use of the kernel's WARN_ON() family of macros, which developers were told to use instead, is also being discouraged.
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Weighted memory interleaving and new system calls
Gregory Price recently posted version 4 of a patch set that adds support for weighted memory interleaving — allowing a process's memory to be distributed between non-uniform memory access (NUMA) nodes in a more controlled way. According to the performance measurements he includes, the patch set could provide a significant improvement for computers with network-attached memory. The patch set also introduces new system calls and paves the way for future extensions intended to give processes more control over their own memory.
Modern computers can have a variety of kinds of memory in use at the same time. Not just traditional NUMA between separate banks of RAM within the same computer, but also memory distributed across a data center, like Compute Express Link (CXL) attached memory. These technologies allow computers to support much larger amounts of memory, at the cost of significantly complicating memory management and slower memory access speeds.
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A change in direction for security-module stacking?
The long-running effort to complete the work on stacking (or composing) the Linux security modules (LSMs) recently encountered a barrier—in the form of a "suggestion" to discontinue it from Linus Torvalds. His complaint revolved around the indirect function calls that are used to implement LSMs, but he also did not think much of the effort to switch away from those calls. While it does not appear that a major course-change is in store for LSMs, it is clear that Torvalds is not happy with the direction of that subsystem.