Linux 6.3 ARM64 Changes Land With SME 2 & SME 2.1 Support

Written by Michael Larabel in Arm on 25 February 2023 at 06:30 AM EST. Add A Comment
Along with all of the Arm SoC and board updates that were merged to the mainline Linux 6.3 kernel earlier in the week, the ARM64 (AArch64) architecture changes have also landed for this next Linux kernel version.

Most notable with the ARM64 changes for Linux 6.3 is the kernel side support for Scalable Matrix Extension 2. Both SME 2 and SME 2.1 support for the kernel changes are in place. Scalable Matrix Extension Version 2 and 2.1 add a new 512-bit architectural register (ZT0) register and new architectural state over SME Version 1 that is already supported by the mainline kernel since Linux 5.19.

It will likely be a while still before seeing any Arm SoCs with Scalable Matrix Extension 2 but it's nice to see the timely enablement for the kernel changes to handle it. The ARM64 changes for Linux 6.3 also include adding Arm SPEv1.2 support, permitting EFI booting with the MMU and caches active, hardening the ARM64 Shadow Call Stack pointer handling, Arm Pointer Authentication clean-ups, and various other fixes and polishing.

The full list of ARM64 feature patches for Linux 6.3 can be found via this pull request that has already been merged to mainline.
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