CXLio

CXLio is a software framework designed to simplify the use of Compute Express Link (CXL) devices in modern data centers. It provides an abstraction layer that helps operating systems, device drivers, and applications discover CXL-capable hardware—such as accelerators, memory expanders, and storage devices—and manage their resources efficiently.

The CXLio stack typically comprises a kernel component for device enumeration and resource management, a userspace library, and optional plugins or drivers for specific hardware. Together they offer a uniform API for creating device namespaces, registering memory regions, performing DMA mappings, and routing IO requests across PCIe and CXL links.

Key features include dynamic device discovery and hotplug support, memory management with registration and protection, I/O virtualization and isolation for multi-tenant environments, robust error handling, and instrumentation interfaces for performance monitoring.

Standards and interoperability: CXLio is designed to align with Compute Express Link specifications, including CXL.io, CXL.mem, and CXL.cache. It aims to provide portable, vendor-agnostic APIs across supported operating systems, with conformance depending on firmware and driver maturity.

Use cases: CXLio enables pooling of memory resources across CPUs, sharing accelerators in virtualized or containerized deployments, offloading I/O workloads from host CPUs, and enabling scalable data-path architectures in dense data-center servers.

Status: CXLio exists as an open, collaborative project in development by an ecosystem of contributors. Its adoption is experimental and depends on hardware support, firmware readiness, and integration with existing system software.