IBM has open-sourced the POWER Instruction Set Architecture (ISA) and hardware reference designs, the company announced at the OpenPOWER Summit. The OpenPOWER Foundation also becomes part of the Linux Foundation.
Open sourcing the POWER ISA means that developers can design chips based on the instruction set royalty-free. In addition to the ISA, IBM is also making a softcore available to the community, which the company got running on a Xilinx FPGA. It represents the first tangible result of opening up the POWER ISA.
Furthermore, IBM is also contributing OpenCAPI and Open Memory Interface (OMI) reference designs. CAPI, OpenCAPI since version 3 as part of an open consortium, is IBM’s standard to attach accelerators to the CPU, similar to CCIX and CXL. A subset of OpenCAPI 3.1 that provides a low-latency protocol for accessing memory is called OMI.
With these open source designs, the OpenPOWER Foundation hopes to grow the OpenPOWER ecosystem, as it is also joining the Linux Foundation. With this step, POWER is becoming a competitor of the relatively young open source RISC-V instruction set that is gaining momentum.
The Instruction Set Architecture (ISA), also called instruction set or simply architecture, is in simple terms the collection of instructions that a processor (a realization of the ISA) can execute; it defines the primitives for a machine language programmer. The implementation, called microarchitecture, typically has a broader impact on the power and performance characteristics, while instruction set extensions target a more narrow, specific set of workloads or algorithms to speed up.