Linux 6.3 Preparing Support For Arm's Scalable Matrix Extension 2 (SME2)

Written by Michael Larabel in Arm on 6 February 2023 at 04:30 PM EST. Add A Comment
While initial Scalable Matrix Extension (SME) support for the Linux kernel only was mainlined last year to the kernel tree, Arm already has SME 2 and SME 2.1 support on the way to mainline.

While it's still not too common finding SVE/SVE2 Arm SoCs or even more so for SME that was announced in 2021 for Armv9-A as a superset of SVE2, Arm is already pushing ahead with mainline kernel support for SME 2/2.1. Scalable Matrix Extension Version 2 and 2.1 add the ZT0 register and new architectural state over SME Version 1 that is already supported by the mainline kernel since Linux 5.19.

There have been the Linux kernel SME 2/2.1 patches floating around the mailing list the past few months for review while now they look set for introduction in Linux 6.3.


Via ARM64's Git tree is a for-next/sme2 branch created toward the end of January and carrying the various SME 2/2.1 patches. With it now going the way of "for-next", it should be ready for sending in when the Linux 6.3 merge window opens later this month -- in two weeks. So at least the kernel-side enablement around Scalable Matrix Extension 2 is ready well in advance of SoCs with this capability.
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Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

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