IBM OpenCAPI (OCXL) coherent accelerator interface
Kernel-side support for OpenCAPI, IBM's coherent host-to-accelerator interconnect used on Power9 servers to attach FPGAs and custom ASICs that share memory with the CPU. It exposes /dev/ocxl character devices so userspace programs can talk to those accelerator cards, a niche mostly seen in HPC and research deployments built around Power9 hardware from roughly 2018 through 2021.
recommendation
Worth keeping but documenting its niche: OpenCAPI is tied to IBM Power9-class servers, which IBM moved into legacy-support status in early 2025 (IBM i 7.5 is named as the last release supporting Power9), and newer Power10 and Power11 systems do not center this interconnect. The code is not abandoned — patches were still landing in late 2023 and beyond — and there is no replacement kernel API offering the same /dev/ocxl userspace contract, so it should remain available for the existing Power9 install base while being clearly labelled as legacy.
repository signals
sources
- docs.kernel.org
Kernel docs describe OCXL as the Linux interface for OpenCAPI accelerators, exposed as /dev/ocxl devices for FPGA/ASIC accelerators attached coherently to the host.
- lore.kernel.org
Lore history shows the driver still receives upstream maintenance patches rather than being abandoned outright.
- ibm.com
IBM's January 2025 planning page says IBM i 7.5 is the last release to support IBM Power9 processor-based systems, placing the platform in legacy-support status.
- ibm.com
IBM's 2025-2026 firmware schedule still lists multiple Power9 systems alongside newer Power10/Power11 models, indicating installed-base support but an older generation.
codex reasoning notes (technical)
OCXL is a real driver for IBM OpenCAPI accelerator hardware. Recommendation is keep-annotate: static history shows meaningful recent maintenance through 2025, and lore evidence includes post-merge cleanup traffic, so this is not a dead/orphaned tree; however deployment is niche and tied to Power9-era OpenCAPI hardware rather than current mainstream platforms. I infer hardware_still_sold_new_in_2025=false and last_widely_available_year=2021 from IBM's Jan 2025 note that Power9 is on its last IBM i-supported release plus IBM's 2025-2026 materials centering newer Power10/Power11 while Power9 appears only as legacy supported systems. No clear upstream replacement driver covers the same OCXL userspace/kernel API, so replacement_driver is null. Source acquisition: docs.kernel URL from web search result; lore URL from lore_file_timeline on drivers/misc/ocxl/main.c; IBM URLs from web search/open/find.