IBM POWER FSI bus and CFAM endpoint stack
FSI (FRU Support Interface) is IBM's low-level service bus that lets a baseboard management controller reach into POWER server processors for boot, debug, and runtime telemetry. The code includes the FSI core bus, host masters on Aspeed AST2600/AST2700 BMCs, and client drivers like SCOM, SBEFIFO, and OCC used on OpenBMC-managed IBM Power9 and Power10 systems.
recommendation
It should stay because the underlying hardware is still sold new: IBM continues to ship Power10 systems such as the S1022 (documentation refreshed February 2025) and ASPEED still markets the AST2700 BMC that the in-tree masters target. Upstream maintenance is active, with bug-fix traffic on fsi-core and the Aspeed master on lkml as recently as April 2026, and no replacement subsystem could absorb its role. Deployment is niche, confined to OpenBMC-managed POWER servers, but the stack remains live and necessary.
repository signals
sources
- lore.kernel.org
April 2026 LKML patch fixes a refcount leak in fsi-core, showing active upstream maintenance in the current cycle.
- ibm.com
IBM markets the Power S1022 as a Power10 server designed to run Linux, indicating the underlying POWER platform is still sold new.
- ibm.com
IBM documentation for the Power S1022 was updated on February 5, 2025, reinforcing that this Power10 platform remains current.
- ibm.com
IBM documents OpenBMC-based management for Power Systems servers, matching the BMC-facing deployment model used by the FSI stack.
- aspeedtech.com
ASPEED still sells the AST2700 BMC family, a current server-management SoC generation relevant to the in-tree Aspeed FSI master support.
codex reasoning notes (technical)
Not an early-exit case: shell inspection of drivers/fsi/Kconfig/Makefile showed a real bus+driver stack (FSI core, Aspeed/GPIO/I2CR masters, SCOM/SBEFIFO/OCC clients), not docs/helpers/tests. Shell-read DT bindings in-tree also showed current Aspeed AST2600 and AST2700 FSI-master compatibles. lore_file_timeline and lore_activity MCP queries produced recent 2026 fix traffic on fsi-core and fsi-master-aspeed; no successful lore evidence of a removal series surfaced. Web-search-obtained IBM and ASPEED URLs show the stack still maps to shipping IBM Power/OpenBMC server hardware. Deployment is niche rather than broad, so 'low' fits, but it is still live and lacks a natural replacement.