Feature: Debug interface

[dpretet]

In order to help debugging and tracing, the core could embed a queue, fed by the master and the slave interfaces, to stream out some events like:

• 4 KB boundary crossing if uses AXI4 protocol
• request / completion timeout
• xRESP with value equals to EXOKAY if uses AXI4-lite protocol
• xRESP with value equals to SLV_ERR
• xRESP with value equals to DEC_ERR

The debug stage must have an input to connect each interface, with a FIFO to store the events, and routing stage to stream the event for instance with an AXI4-stream interface.

The debug could be actionable per interface.

A message / event format must be specified