Linux 6.3 Features: AMD Auto IBRS To Steam Deck Controller Interface, IPv4 BIG TCP & More

Written by Michael Larabel in Software on 6 March 2023 at 12:00 PM EST. Page 1 of 3. 3 Comments.

Now that the Linux 6.3 merge window is over with Linux 6.3-rc1 having been released last night, here is a look at all of the interesting changes, new features, and hardware support coming with this next major kernel version.

For the next roughly eight weeks Linux 6.3 will continue on with testing and bug fixing before being released as stable around late April or early May. Linux 6.3 is another hearty kernel update. Among the changes to find with Linux 6.3 include the new Intel VPU driver for Meteor Lake SoCs, AMD Automatic IBRS for more efficient Spectre V2 mitigations compared to Retpolines for Zen 4 processors, Steam Deck controller interface support in the Steam Controller HID kernel driver, EXT4 DIO performance optimizations, BFQ tuning for multi-actuator hard drives, Arm Scalable Matrix Extensions (SME) 2/2.1 support, Intel TPMI and PMCI drivers added, the Qualcomm ath12k driver for forthcoming WIFi 7 chipsets, IPv4 BIG TCP for better performance, and Microsoft Pluton TPM CRB support.

Tux logo

Below and on the pages ahead is the more exhaustive list of the Linux 6.3 kernel features based on my monitoring of Git and the mailing lists. Now with the Linux 6.3 merge window past, it's onto testing and performance benchmarking of Linux 6.3.


- AMD Automatic IBRS for Zen 4 processors across the Ryzen and EPYC product stacks. Automatic IBRS is akin to Intel eIRBS and is more efficient than Retpolines for Spectre V2 mitigation. This switch from Retpolines to Automatic IBRS can deliver some performance improvements.

- Intel LKGS support for this Load Kernel GS instruction as part of their upcoming FRED feature.

- Linux kernel preparations for Arm SME2 and SME2.1 as Arm's Scalable Matrix Extensions.

- New Arm and RISC-V power management drivers.

- Optimized string functions for RISC-V by making use of the Zbb bit manipulation extension.

- The Intel TPMI driver was merged for this Topology Aware Register and PM Capsule Interface to be used for dealing with different power management features.

- Intel TDX updates to avoid a "total insanity" scenario.

- The AMD-Xilinx XDMA driver has been merged for this Xilinx Direct Memory Access (DMA) subsystem.

- AMD Slow Memory Bandwidth Allocation Enforcement for Zen 4 server processors.

- Qualcomm Snapdragon 8 Gen 2 support.

- Various RAS and EDAC updates for AMD and Intel servers -- including 12 channel DDR5 for Granite Rapids.


Graphics / Compute Accelerators:

- The Intel Meteor Lake VPU driver was merged for this "Versatile Processing Unit" premiering in next-gen Meteor Lake SoCs. The VPU will be used for AI inference purposes. This is the first new driver making use of the compute accelerator "accel" subsystem that was started in Linux 6.2.

- Intel's Habana Labs AI driver has also been adapted for the new compute accelerator subsystem/framework.

- Intel Meteor Lake display support is working. Intel engineers have been working on enabling the Meteor Lake graphics support for some months now and starting with Linux 6.3 it's at least capable of driving a display.

- Intel DP MST DSC support.

- Various old drivers have been removed like for the ATI Rage 128, 3Dfx, S3 Savage, Intel 810, SiS, VIA, and more.

- AMDGPU now exposes PCIe information to user-space.

- AMDGPU also has a rework to the S0ix suspend code.

- Etnaviv now supports VeriSilicon NPU cores with pending work to enabling OpenCL on the NPUs with Mesa.

- Various other Direct Rendering Manager (DRM) updates.

- Analog TV support improvements.

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