riscv-software-src / riscv-software-src/opensbi

What is the best way to setup a core to be visible in M-mode but not by an operating system in S/U-mode?

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C
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Description

I am currently contributing to Keystone (https://github.com/keystone-enclave/keystone) which utilizes OpenSBI, and we are currently trying to achieve this behavior:

We want to have a system with a "management core" such that this core is visible to the M-mode supervisor, but not to anything else (i.e. an operating system and its applications in S/U-mode).

We are not quite sure how to best achieve this with OpenSBI as it is currently -- do you guys have any thoughts on how best to achieve this? We've made some modifications in our private fork of OpenSBI, but we would of course like to stick with the standard release of OpenSBI as much as possible. We are also thinking this may need the changes we suggested in this issue: https://github.com/riscv-software-src/opensbi/issues/297

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reviewing OpenSBI's current handling of hart visibility and the related proposal in issue #297. Determine whether standard OpenSBI already supports hiding a management core from S/U-mode, or whether a defined design and implementation change is needed; done means a documented, agreed approach or an actionable implementation plan.

Written by the indexing model from the issue text.

Assessment

Tech stack
c
Domain
operating-systems
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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