P28 takes the P27 trap path and gives it event sources.
Commands:
make -C projects/28_rv32i_machine_interrupts/test
make -C projects/28_rv32i_machine_interrupts/test act4Results:
| check | result |
|---|---|
| Directed CSR/trap regression | PASS |
| Masked timer pending test | PASS |
Timer interrupt with mret | PASS |
| External interrupt handler | PASS |
ACT4/Sail rv32i/I | PASS=39 FAIL=0 NOT RUN=0 |
| Hardening | NOT RUN |
| Official privileged tests | NOT RUN |
The useful part is that the interrupt plumbing did not disturb the base
integer ACT4 result. The honest caveat is that the timer registers are custom
teaching CSRs at 0x7c0 and 0x7c1; real RISC-V platforms normally expose
mtime and mtimecmp as memory-mapped platform registers.
Next, P29 should stop using that shortcut and make a real small-system memory map: ROM, RAM, UART, timer MMIO, and external interrupt wiring.