How to enable many RoCC accelerators with RocketChip?

[shibizhao]

Dear authors,

I am a beginner with Chipyard, and I am curious about the RoCC extension.

Here are some questions I would like to know.

1. I found the limitations of #RoCC Accelerators are four from this page: https://chipyard.readthedocs.io/en/stable/Customization/RoCC-or-MMIO.html. And I would like to know how I can extend more than four RoCC accelerators with a single core.
2. I have instantiated a Rocketchip with a Rocket core and a simple RoCC accelerator. And I think that when the accelerator is running, this RoCC instruction will be blocked in the Rocket CPU pipeline. When there are multiple RoCC accelerators, how can I enable their execution (in parallel or with an async mode) in a core? I think the in-order Rocket core cannot achieve this. Whether a Boom core can accomplish this execution mode?

Thanks for your time. Look forward to your reply :)