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RISC-V Design ยท All levels

Core Cluster Integration: Debug Playbook

Debug Playbook for Core Cluster Integration.

Debug playbook

Debug Playbook for Core Cluster Integration is anchored on Cluster-level boot success rate and coherent interconnect stability under mixed interrupt, DMA, and cache-coherency traffic.. Convert observations into mechanism-backed decisions with explicit ownership.

  1. Freeze workload seed, binary, compiler, firmware, and platform setup.

  2. Find earliest persistent mechanism failure in the timeline.

  3. Build one reduced reproducer for dominant hypothesis.

  4. Patch minimal fix with explicit rollback gate.

  5. Rerun correctness + performance + power matrix.

Decision tree

diagram
ROOT CAUSE TREE - Core Cluster Integration

Cluster-level boot success rate and coherent interconnect stability under mixed interrupt, DMA, and cache-coherency traffic. regressed
          |
   reproducible on fixed seed?
      /                 \
    no                   yes
    |                     |
env/tool drift       first failing domain?
                     /        |         \
                  decode    execute    memory/MMU
                    |         |            |
               control map  bypass/FU   TLB/walk/perm
                    |
         privilege/CSR side effects checked?

Stop at first confirmed mechanism, then assign explicit owner + fix proof.

Review memo template

diagram
RISC-V REVIEW MEMO - SoC Integration & Bring-up / Core Cluster Integration

1. Symptom
   - Failing metric: Cluster-level boot success rate and coherent interconnect stability under mixed interrupt, DMA, and cache-coherency traffic.
   - Failing workload slice: <name>
   - Triggering mode: <privilege/virtualization/interrupt/cache/boot>
   - Build and runtime tags: <toolchain/firmware/RTL revision>

2. Mechanism hypothesis
   - Primary mechanism: Integrating a RISC-V core cluster is more than wiring CPU instances to a bus: cache hierarchy policy, interrupt routing, clock/reset sequencing, debug access, and coherency ordering all interact. Platform teams must validate that cluster-local assumptions (TLB shootdown timing, cache maintenance behavior, and atomics support) remain correct when connected to shared L3, IO masters, and accelerators. Misaligned assumptions here create failures that look like random software hangs but are usually deterministic integration defects under concurrency. Bring-up readiness comes from interface contract checks, stress-driven coherency tests, and observability hooks that connect firmware events to hardware state transitions.
   - Competing hypotheses: <decode control / hazard / MMU / privilege / integration>
   - Missing evidence: <trace/counter/proof/report>

3. Proposed action
   - Smallest reversible change: <RTL/compiler/runtime/config>
   - Expected movement: <throughput/latency/tail/perf-per-watt>
   - Regression risk: correctness, security, power, timing, software compatibility

4. Signoff
   - Required artifact: Cluster integration dossier: interface contract matrix, coherency stress results, interrupt-latency traces, and reset/clock sequencing checklist.
   - Required owners: SoC architect, CPU subsystem owner, interconnect architect, verification lead, firmware owner
   - Final decision: ship, bounded rollout, rollback, or escalate
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