PowerCommons A2O - A2O Core Revival

Project Overview

The PowerCommons A2O initiative revives and modernizes IBM’s A2O processor core - a proven architecture that powered the world’s most powerful supercomputers. By making this enterprise-grade technology accessible on modern FPGA platforms, we’re democratizing access to high-performance, transparent computing.

Project Status: 🟡 Active Development
Timeline: September 2025 - March 2026 Funding: €50,000 (NLnet Foundation - pending)
Repository: codeberg.org/PowerCommons/powercommons-a2o

Why A2O?

Proven Heritage

The A2O processor isn’t experimental - it’s battle-tested technology that ran in production for years:

• Powered Blue Gene/Q supercomputers
• Achieved 16.32 petaflops in Sequoia system
• Demonstrated reliability at massive scale
• Optimized for power efficiency

Technical Excellence

• 64-bit PowerPC Architecture: Full ISA 2.06 compliance
• Out-of-Order Execution: Advanced performance optimization
• Multi-Threading: 4-way SMT capability
• Vector Processing: QPX floating-point unit
• Cache Hierarchy: Sophisticated L1/L2 cache design

Open Liberation

IBM released A2O as open source, but the code has suffered from:

• Incompatibility with modern toolchains
• Broken build systems
• Missing documentation
• Lack of community support

PowerCommons fixes these issues, making A2O accessible to everyone.

Technical Objectives

Phase 1: Infrastructure Setup (Months 1) 🚧✅

• Assess current codebase state
• Identify toolchain incompatibilities
• Document build requirements
• Establish development environment

Phase 2: Core Revival, Implementation & Software (Months 3-4) 🚧

• Fix Vivado 2025.x compatibility issues
• Resolve timing closure problems
• Update synthesis constraints
• Create automated build system

Phase 3: Integration and Documentation (Months 5-6) 📋

• Implement missing peripherals
• Add LiteX integration
• Create FPGA reference designs
• Roadmap

Current Challenges

Build System Issues

// Example of outdated synthesis directive
(* ram_style = "block" *)  // Vivado 2025 requires different syntax
reg [63:0] cache_data [0:1023];

The original build system uses obsolete Xilinx tools and scripts incompatible with modern Vivado versions.

Timing Closure

Critical paths in the original design exceed timing constraints on modern FPGAs:

• Cache access paths
• Out-of-order execution logic
• Vector unit operations

Software Stack

Limited software support requires development of:

• Modern GCC toolchain
• Linux kernel patches
• Bootloader implementation
• Debug infrastructure