The AXI Firewall IP is designed to detect potentially fatal conditions on the monitored interface. An AXI protocol violation is considered potentially fatal if there is a high likelihood that it would corrupt the state of the AXI interface and interfere with ongoing operation. There are additional protocol violations listed in the AXI Protocol Specification that are not considered potentially fatal if they are likely to only corrupt the transported payload without interfering with the on-going operation of the AXI interface. The AXI Firewall IP core does not implement checks for non-fatal protocol violations, to save area.
The fault(s) causing the block are readable through the control interface, and remain unchanged until the block is cleared. Specifically, during the first cycle in which any read or write fault is triggered, the MI-Side Fault Status Register/SI-Side Fault Status Register captures all checks that are asserted during that cycle, but no subsequently triggered checks (within read or write) change the value of the read/write field of the MI-Side Fault Status Register/SI-Side Fault Status Register.