VFIO passthrough for AMD/Xilinx CDX bus devices on Versal Adaptive SoCs
Provides userspace and virtual-machine passthrough access to devices on the CDX bus, a custom interconnect AMD/Xilinx uses on its Versal Adaptive SoC platforms (FPGA-plus-CPU chips aimed at networking, datacenter, and embedded workloads). It lets hypervisors or DPDK-style userspace applications drive FPGA-attached functions directly, similar to how VFIO already works for PCI devices.
recommendation
It should stay because the code is young (added in 2023), still receiving real maintenance into 2026 including race-condition and null-pointer fixes, and there is no alternative path for passing CDX-bus devices through to virtual machines or userspace. AMD continues to ship current Versal silicon and even packages a cdx-controller module in its own release artifacts, so although the deployed base is small and specialized, the hardware is actively sold and the driver has a clear ongoing purpose.
repository signals
sources
- spinics.net
Public mailing-list traffic shows active 2026 maintenance for vfio/cdx, including race and NULL-dereference fixes.
- cateee.net
LKDDb shows CONFIG_VFIO_CDX exists from Linux 6.5 through current development kernels, indicating an actively carried in-tree driver rather than abandoned legacy code.
- kernel.org
Kernel ABI docs still document sysfs for the CDX bus, showing the underlying bus/subsystem remains part of current kernel interfaces.
- amd.com
AMD still markets current Versal Adaptive SoCs, a contemporary product family plausibly hosting CDX-based devices.
- edf.amd.com
AMD/Xilinx release artifacts include a cdx-controller kernel module package, indicating vendor-supported deployments rather than purely historical hardware.
codex reasoning notes (technical)
Local shell inspection (`rg` in-tree) confirmed this is a real driver: Kconfig entry, `module_driver(...)`, and VFIO ops for CDX bus devices. Local `git -c safe.directory=... log -- drivers/cdx drivers/vfio/cdx` showed creation in 2023 and substantive updates through 2026-02, so there is no sign of stagnation. Web search found the spinics thread with active 2026 bug-fix work and no removal/deprecation discussion. Web search also found LKDDb and current kernel ABI docs showing CDX remains present upstream. AMD product pages and release-package indexes obtained via web search indicate the surrounding AMD/Xilinx adaptive-SoC ecosystem is still current, but specialized; that supports `deployments_today = low` rather than medium/high. No natural replacement driver exists for VFIO access to CDX-bus devices, so removal/deprecation is not justified.