title: RISC-V spec references the word 'hart' - what does 'hart' mean?
body: <p>I found references to <em>hart</em> on page 35 of the <a href="https://content.riscv.org/wp-content/uploads/2016/06/riscv-spec-v2.1.pdf" rel="noreferrer">RISC-V 2.1 spec</a>. However, I could not find a definition for <em>hart</em> in this document. Does hart refer to a hardware-thread or something more sinister? </p>