scarv/scarv-cpu

External interrupt causes and NMI

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ben-marshall commented

Currently the CPU supports two external interrupt sources:

  • int_external
  • int_software

These should be extended in the following ways:

  • Add a non-maskable interrupt pin (NMI). This should have it's own documented cause code.
  • Add a cause field to the int_external line which finds its way to mcause when such an interrupt is taken.
  • Add a cause field to the int_software line which finds its way to mcause when such an interrupt is taken.
ben-marshall commented

Decided against cause code for software interrupts. Expect software to figure this out.