Linux 5.13 Adding KCPUID For Helping To Bring-Up New x86 CPUs

Written by Michael Larabel in Linux Kernel on 26 April 2021 at 07:07 AM EDT. 2 Comments
The "x86/misc" pull request this morning for the newly-opened Linux 5.13 merge window adds the new KCPUID utility contributed by Intel.

KCPUID is being added to the Linux kernel source tree by Intel for reporting CPU features as an alternative to the likes of /proc/cpuinfo. KCPUID s a utility to live within the kernel source tree for reliably reporting raw CPU features where as /proc/cpuinfo can sometimes misreport if features were disabled at boot-time and prior to new feature bits being added for /proc/cpuinfo reporting.

There are other user-space utilities for reporting CPU features but they aren't always necessarily up-to-date. By keeping KCPUID within the kernel source tree and being maintained by open-source Intel engineers, the hope is this will always be up-to-date. KCPUID relies upon CPUID leaf definitions stored within a CSV file and thus very easy to add new entries.

With the ease of adding new CPUID leafs and being part of the kernel source tree, Intel for their part appears interested in using this tool for hardware enablement of new features on pre-production x86 processors. Most users will still be best off just relying on /proc/cpuinfo but for those bringing up new x86 processor features, KCPUID within the kernel source tree may prove convenient and its straight-forward manner of adding new information via the CSV file.

Adding KCPUID for Linux 5.13 was the main change of today's x86/misc pull.
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