This demo introduces Reptiles - Repeated Tiles of Sargantana, an open-source RISC-V multicore architecture designed to support research in HPC systems. Reptiles builds upon the OpenPiton manycore framework by integrating multiple Sargantana RISC-V cores and enhancing the memory hierarchy and interconnection network to improve scalability and performance. The goal is to provide an accessible and flexible platform for researchers to develop, experiment with, and optimize HPC workloads using open hardware.

Reptiles replicates Sargantana tiles within OpenPiton’s architecture and introduces several architectural improvements. These include a configurable network-on-chip width (from 64 up to 704 bits), flexible cache block sizes, adjustable numbers of miss status holding registers (MSHRs), improved cache sizes and associativities, parallel SRAM access in the L2 and the last-level cache, and configurable number of memory controllers. The system also integrates the High-Performance Data Cache (HPDcache) as an L1 data cache and enhances the Sargantana core with broader support for RISC-V extensions, particularly the RISC-V Vector Extension (RVV 1.0). Additional improvements include debugging support, performance counter access in Linux, and enhanced RTL simulation features such as checkpointing.

In this demo we show a fully functional FPGA prototype of Reptiles with four Sargantana cores booting Linux and running OpenMP benchmarks such as the NAS Parallel Benchmarks, interactive UART console games, and graphical applications by performing X11 forwarding over SSH. Overall, Reptiles demonstrates that open-source RISC-V multicore systems can effectively support scalable HPC research and experimentation.