New Linux Kernel Patch Allows Forcing a CPU Mitigation
Even when CPU mitigations can consume precious CPU cycles, it might not be a bad idea to allow users to enable them, even if your machine isn't vulnerable.
As reported by Phoronix, Brendan Jackman, a Google engineer, issued a patch that introduces a new Linux boot parameter, force_cpu_bug=. When enabled, the kernel assumes the CPU is affected by a bug such as Spectre, Meltdown, or Retbleed and reacts accordingly.
But why would you want to do this, especially when your machine isn't affected? According to Jackman's post on the force_cpu_bug patch, "It's a bit unfortunate that we have to do this by bug instead of by mitigation. However, we don't have clear identifiers for the mitigations that we do, so I don't think it's practical to do better here than ‘you can pretend you're on a vulnerable CPU – now go and read the docs for the per-vuln cmdline params to figure out how to run the mitigation you want.’"
But why would anyone want to run this command-line boot option, especially when it's very likely to prevent the machine in question from achieving its full potential? Jackman says (in his patch), "This can be handy for mundane reasons like ‘I wanna debug this on the machine that quickly.’”
He continues to say that it can also be helpful for research, "while some mitigations are focussed on individual vulns and uarches, others are fairly general, and it's strategically useful to have an idea how they'd perform on systems where we don't currently need them."
Jackman's patch has to go through the usual process, during which it will be determined if it is of use for mainline release. You can view Jackman's original patch here.
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
-
AlmaLinux 10.0 Beta Released
The AlmaLinux OS Foundation has announced the availability of AlmaLinux 10.0 Beta ("Purple Lion") for all supported devices with significant changes.
-
Gnome 47.2 Now Available
Gnome 47.2 is now available for general use but don't expect much in the way of newness, as this is all about improvements and bug fixes.
-
Latest Cinnamon Desktop Releases with a Bold New Look
Just in time for the holidays, the developer of the Cinnamon desktop has shipped a new release to help spice up your eggnog with new features and a new look.
-
Armbian 24.11 Released with Expanded Hardware Support
If you've been waiting for Armbian to support OrangePi 5 Max and Radxa ROCK 5B+, the wait is over.
-
SUSE Renames Several Products for Better Name Recognition
SUSE has been a very powerful player in the European market, but it knows it must branch out to gain serious traction. Will a name change do the trick?
-
ESET Discovers New Linux Malware
WolfsBane is an all-in-one malware that has hit the Linux operating system and includes a dropper, a launcher, and a backdoor.
-
New Linux Kernel Patch Allows Forcing a CPU Mitigation
Even when CPU mitigations can consume precious CPU cycles, it might not be a bad idea to allow users to enable them, even if your machine isn't vulnerable.
-
Red Hat Enterprise Linux 9.5 Released
Notify your friends, loved ones, and colleagues that the latest version of RHEL is available with plenty of enhancements.
-
Linux Sees Massive Performance Increase from a Single Line of Code
With one line of code, Intel was able to increase the performance of the Linux kernel by 4,000 percent.
-
Fedora KDE Approved as an Official Spin
If you prefer the Plasma desktop environment and the Fedora distribution, you're in luck because there's now an official spin that is listed on the same level as the Fedora Workstation edition.