What is RISC-V and why should we care?

RISC-V is an open Instruction Set Architecture (ISA) standard which enables the open development of CPUs and a shared common software ecosystem. With billions of RISC-V cores already produced, and this is accelerating rapidly, we are seeing a revolution driven by open hardware. Nonetheless, for all the successes that RISC-V has enjoyed, it is yet to become mainstream in HPC. This comes at a time when HPC is facing new challenges, especially around performance and sustainability of operations, and recent advances in RISC-V such as data centre RISC-V hardware make this technology a more realistic proposition with potential to address these. In this survey paper we explore the current state of art of RISC-V for HPC, identifying areas where RISC-V can benefit the HPC community, the level of maturity of the hardware and software ecosystem for HPC, and identify areas where the HPC community can contribute. The outcome is a set of recommendations around where the HPC and RISC-V communities can can come together and focus on high priority action points to help increase adoption.