Any documentation on RoCC interrupt and exception?

[pepper-lees]

Hi,

I noticed in UCB's very helpful Your First Accelerator: Matrix Sum that they mentioned an interrupt signal in RoCCCommand, which I see inside LazyRoCC.scala.

To help both myself and others, I'm thinking of adding short Javadoc comments explaining each signals and submitting a PR. I can infer info about most signals, but I don't quite understand the difference between interrupt and exception. What do they do & represent? And if you run an RoCC instruction (e.g. ROCC_INSTRUCTION_DS) what would one expect to happen when the interrupt signal goes high? Thanks!

class RoCCCoreIO(implicit p: Parameters) extends CoreBundle()(p) {
  /** Incoming command from the associated processing core. */
  val cmd = Flipped(Decoupled(new RoCCCommand))
  /** Outgoing result to the associated processing core. */
  val resp = Decoupled(new RoCCResponse)
  /** Memory interface to HellaCache, the L1 cache on a Rocket Chip. */
  val mem = new HellaCacheIO
  /** Indicate to the processor that the accelerator is currently doing work. */
  val busy = Output(Bool())
  /** ??? */
  val interrupt = Output(Bool())
  /** ??? */
  val exception = Input(Bool())
}