AMD has taken up support for modern EPYC in FreeBSD

The FreeBSD Project has published a report for the second quarter of 2024, which describes the work done by leading BSD developers. According to Phoronix, among the FreeBSD Foundation’s completed tasks in the last quarter are projects to improve the audio stack, improve OpenZFS, port VPP (Vector Packet Processing) to FreeBSD, and improve wireless network support.

It also became known that AMD and the FreeBSD Foundation are collaborating on the development of a full AMD IOMMU driver. The goal of the project is to improve support for AMD EPYC-based servers in FreeBSD, including those with more than 256 cores, integration with the Bhyve virtualization system, and other improvements.

«Work continued on the joint project between Advanced Micro Devices (AMD) and the FreeBSD Foundation to develop the AMD IOMMU driver. This driver will allow FreeBSD to fully support over 256 cores with features such as CPU mapping, and will also include Bhyve integration. Konstantin Belousov worked on various parts of the project, including driver connection, register definition, ACPI table parser, and utility function implementation. The two key components that need to be completed are context processing, which is basically a generalization of the Intel DMAR code, and page table generation. After this, you can activate the AMD driver for testing. To follow Konstantin’s work, look for commits in the repository tagged “Sponsored by fields for Advanced Micro Devices (AMD) and The FreeBSD Foundation,” the report says.

Image source: FreeBSD

The emergence of AMD’s support for the FreeBSD community is a significant event, since previously only Intel was famous for actively contributing to the development of the project and providing engineering resources over the years. In this light, I wonder whether AMD’s support is a gesture of goodwill or whether the company has customers who require compatibility and optimizations for FreeBSD. Among the major players whose infrastructure actively uses FreeBSD, there is, for example, Netflix. In recent years, Arm has also become actively involved in OS development.

In addition, FreeBSD continues to actively support the RISC-V architecture. So, there is already experimental support for Bhyve. In addition, one of the new developments for the FreeBSD kernel was the creation of Zcond, a lightweight conditional execution mechanism similar to the static_key interface in Linux.