Zack's Kernel News
Zack's Kernel News
Chronicler Zack Brown reports on the latest news, views, dilemmas, and developments within the Linux kernel community.
NMI Refactor And Simplification
Andy Lutomirski wasn't satisfied with the non-masking interrupt (NMI) system, as implemented in the Linux x86 architecture. An NMI is when the system hardware interrupts the normal flow of code execution in order to perform a task that's so important it can't be ignored or deferred by the operating system. For example, if the system detects bad memory, it might trigger an NMI that would halt the OS.
But even – maybe especially – in such dire circumstances, it's important for the kernel to behave in as orderly a way as possible to preserve user data and leave the system in as consistent a state as possible. One NMI may occur within another, depending on the cause of the interrupts. That nesting has to be handled gracefully, and code sometimes needs to know whether it was called from within another NMI – information that is notoriously tricky to determine. However, Andy reported that in the current code, in certain corner cases, NMIs could nest improperly, malicious user code could cause some NMIs to be ignored entirely, and some code paths simply handled NMIs incorrectly because the kernel code was wrong.
He posted some patches to try to fix things up but quickly found himself plunging down the rabbit's hole of nested NMI call subtlety, as he discovered more about how the existing NMI code behaved. The whole discussion was fascinating.
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
US / Canada
UK / Australia
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
CIQ Releases Security-Hardened Version of Rocky Linux
If you're looking for an enterprise-grade Linux distribution that is hardened for business use, there's a new version of Rocky Linux that's sure to make you and your company happy.
-
Gnome’s Dash to Panel Extension Gets a Massive Update
If you're a fan of the Gnome Dash to Panel extension, you'll be thrilled to hear that a new version has been released with a dock mode.
-
Blender App Makes it to the Big Screen
The animated film "Flow" won the Oscar for Best Animated Feature at the 97th Academy Awards held on March 2, 2025 and Blender was a part of it.
-
Linux Mint Retools the Cinnamon App Launcher
The developers of Linux Mint are working on an improved Cinnamon App Launcher with a better, more accessible UI.
-
New Linux Tool for Security Issues
Seal Security is launching a new solution to automate fixing Linux vulnerabilities.
-
Ubuntu 25.04 Coming Soon
Ubuntu 25.04 (Plucky Puffin) has been given an April release date with many notable updates.
-
Gnome Developers Consider Dropping RPM Support
In a move that might shock a lot of users, the Gnome development team has proposed the idea of going straight up Flatpak.
-
openSUSE Tumbleweed Ditches AppArmor for SELinux
If you're an openSUSE Tumbleweed user, you can expect a major change to the distribution.
-
Plasma 6.3 Now Available
Plasma desktop v6.3 has a couple of pretty nifty tricks up its sleeve.
-
LibreOffice 25.2 Has Arrived
If you've been hoping for a release that offers more UI customizations, you're in for a treat.