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Support for post-syn testing #60

ducky64 opened this issue Aug 26, 2019 · 2 comments


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@ducky64 ducky64 commented Aug 26, 2019

Apparently a requirement for practically building chips.


  • Support for using blackbox as the module passed into a test() function, so that we don't need to re-elaborate to Chisel circuit.
  • Separation of circuit interface (potentially the blackbox solution as above, or a full Chisel elaborated module that we discard the circuit for) and implementation (which you can plug in a separate Verilog module or something)
  • Potentially a blackbox where you can specify a FIRRTL file, or some other file that contains data like combinational paths for cross-thread-ops checking or implicit clock resolution.

@seldridge, @jackkoenig ?


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@seldridge seldridge commented Aug 26, 2019

I have viewed the second bullet point as the critical problem and path to a solution. Chisel intermixes specification (IO) and implementation (module internals) whereas other languages opt to make this explicit (VHDL has specification/implementation). Because of this, it's difficult in Chisel to think about abstracting over implementations.

I've used the following recently as something towards this:

/** A [[Module]] mixin that exposes the type of the underlying IO
  * @tparam A the type of the [[Module]]'s IO
trait Spec[A <: Record] { this: Module =>
  override val io: A

I was then able to write tests for any Module with Spec[A]. However, there then needs to be some means to convert between different module types and blackboxes. A typeclass interface object pattern worked here with toLegacy and toBlackBox methods.

This is likely related to programmatic IO discoverability.

@ducky64 ducky64 added this to the 0.1 Basic usability milestone Sep 16, 2019

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@edwardcwang edwardcwang commented Dec 2, 2019

Related: #2

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