chipsalliance / chipsalliance/rocket-chip

mtval not written after ebreak

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#2,348 3 comments 0 reactions 0 assignees View on GitHub

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bug build: emulator
Dominant language
Scala
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Description

Type of issue: bug report

Impact: unknown

Development Phase: proposal

Other information

Spec says mtval register is written with the faulting virtual address when a hardware breakpoint is triggered, but Rocket chip does not save the address to mtval register when ebreak instruction is executed. Is it intended?

Here's all my test and logs as before.

test.zip

Contributor guide

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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 the RISC-V behavior described in the issue and reproducing the report with the attached test.zip and its logs. Trace how Rocket Chip handles ebreak and writes mtval, then verify the result against the cited specification; done means the reported mtval behavior is corrected or its intended behavior is documented.

Written by the indexing model from the issue text.

Assessment

Tech stack
scala
Domain
embedded-iot
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Active
Clarity
Mostly clear
Newbie friendliness
48/100

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