PROMPT
You see deadlock signature, ordering violation count, coherency timeout rate on Coherence Fabric Debug. Walk through root cause and fix.

STRONG ANSWER
1. Names the layer and transaction identity.
2. Explains debug requires correlating transaction IDs, cache-line addresses, state transitions, and fabric backpressure.
3. Requests coherence trace, litmus replay, fabric credit graph, failing line timeline.
4. Proposes one reduced sequence and one system regression.

WEAK ANSWER
Jumps to widening the interface, increasing FIFO depth, or blaming firmware without evidence.

DEADLOCK = CYCLE IN THE WAIT GRAPH

  A waits on response channel held by B
        ^                         |
        |                         v
  B waits on snoop channel held by A

Break the cycle with:
  - separate virtual channels per message class
  - guaranteed sink for responses/snoops
  - no protocol message blocked behind another class

ROOT-CAUSE TREE — Coherence Fabric Debug

deadlock signature, ordering violation count, coherency timeout rate looks wrong
        |
   reproducible?
     /        \
   no          yes
   |            |
 flaky env   same first transaction every time?
 / seed         /            \
              yes             no
               |               |
        protocol rule     timing/reset/PVT
        or config bug     or load-dependent

COHERENCE TRAFFIC FLOW

RN issues coherent read
   -> HN looks up directory
   -> snoops to sharers
   -> data + state update returned

False sharing: different variables, same cache line -> coherence storm.

COHERENCY TRAFFIC STACK

data fetch        ████████
snoop responses   ██████████████
writebacks        ██████
maintenance ops   ████

High snoop stack with good IPC -> suspect line sharing before faster NoC.