AMD Versal CDX bus controller
Controller-side support for the CDX bus on AMD (formerly Xilinx) Versal adaptive SoCs and FPGAs, where dynamically-configured FPGA logic blocks are exposed to Linux running on the chip's Arm application cores. It handles communication between the application processor and the real-time processor that manages the FPGA fabric, typically via a remote-processor messaging channel.
recommendation
It should stay because the underlying AMD Versal adaptive SoC family is still being sold and marketed in 2025, including newer Gen 2 variants, and the code is actively maintained: MSI support landed in 2024 and further functional fixes and symbol exports went in as recently as September 2025. The /sys/bus/cdx interface is a documented, supported kernel ABI, and since this is the controller implementation for the CDX bus itself, no replacement exists. Deployment is niche (embedded FPGA workloads) but the driver is clearly current.
repository signals
sources
- git.kernel.org
Upstream activity remained real in 2025 with a functional CDX-controller change: symbol export and MCDI/RPC initialization work landed on 2025-09-08.
- git.kernel.org
The driver gained MSI support in 2024, indicating active feature development rather than retirement.
- kernel.org
Kernel ABI documentation includes /sys/bus/cdx interfaces, showing CDX is an exposed supported bus/userspace interface rather than dead code.
- amd.com
AMD continued marketing the Versal adaptive SoC family, including Gen 2 variants, in and after 2025; the underlying hardware family is still sold new.
- docs.amd.com
AMD Versal documentation describes both APU and RPU subsystems, matching the CDX driver's APU/RPU split architecture used for controller communication.
codex reasoning notes (technical)
Real driver, not a helper library: local source inspection via shell showed module/platform-driver code in cdx_rpmsg.c and CDX bus/controller logic tied to AMD FPGA devices. Upstream activity was checked with local `git log` (lei/lore tooling unavailable here): recent non-treewide commits in 2025 include functional fixes and exports, and I found no removal-oriented history. URLs for the two kernel commits are canonical git.kernel.org commit pages inferred from the local commit IDs; AMD product/TRM URLs and kernel ABI doc were obtained via web search. Hardware is still current but niche embedded/FPGA infrastructure, so deployments today are low rather than none. No obvious replacement driver exists because this is the bus/controller implementation for CDX itself.