AMD & FreeBSD Begin Collaborating Over OS Improvements

The FreeBSD open-source operating system project published their Q2'2024 status report that outlines some interesting work happening to this leading BSD project.

Among the work the past quarter, the FreeBSD Foundation has been sponsoring projects to work on enhancing the audio stack, hierarchical rate limits for OpenZFS, porting of the Vector Packet Processor (VPP) to FreeBSD, and improving wireless networking support on FreeBSD. Of the audio stack work for FreeBSD has been to enable async audio device detach, sound crashes and fixes, more out of the box support for the "snd_hda" laptop audio hardware, fixes around the OSS API, and started working on the audio OSS audio / MIDI library. FreeBSD has acknowledged their audio support doesn't receive as much attention as it could but there are developers working to improve the situation. 

Also interesting is that AMD and the FreeBSD Foundation have been collaborating to develop a complete FreeBSD AMD IOMMU driver. The intent is for FreeBSD to better support more than 256+ CPU cores, Bhyve integration, and other improvements for AMD EPYC servers on FreeBSD. The Q2'2024 status report notes: 

"Work continued on a joint project between Advanced Micro Devices (AMD) and The FreeBSD Foundation to develop a complete FreeBSD AMD IOMMU driver. This work will allow FreeBSD to fully support greater than 256 cores with features such as CPU mapping and will also include bhyve integration. Konstantin Belousov has been working on various parts of the project, including driver attachment, register definitions, an ACPI table parser, and utility functions. Two key components that need to be completed are context handling, which is mostly a generalization of Intel DMAR code, and page table creation. After this, the AMD driver’s enable bit can be turned on for testing. To follow all of Konstantin’s work, look for src commits tagged with Sponsored by fields for Advanced Micro Devices (AMD) and The FreeBSD Foundation."

This is great to see happen with Intel typically better regarded for their FreeBSD support and engineering resources they have contributed over the years. Intel engineers have contributed a lot directly to FreeBSD over the years while Arm has also been making more inroads in recent years too.

Separately, FreeBSD continues seeing more work around RISC-V support including for the StarFive JH7110 SoC / VisionFive v2 and T-HEAD/XuanTie CPU. There is also experimental support for the RISC-V hypervisor within Bhyve.

A new innovation happening for the FreeBSD kernel is that "Zcond" is being developed as a low-cost conditional execution mechanism similar to Linux's static_key interface.

More details on all of these interesting FreeBSD projects for the past quarter via the FreeBSD.org report.