The AXI Firewall IP actively checks for certain potentially fatal issues in the AXI forward transfers received on the AR, AW, and W channels of the SI. When any of the enabled read or write fault conditions are detected on the associated forward channel of the SI, the AXI Firewall IP blocks further read or write transfers between the SI and MI. Separate firewall blocking conditions are imposed for read and write faults.
If the block is triggered by a protocol violation fault in
a forward transfer, the transfer exhibiting the violation is not propagated
to the MI. The block condition is indicated through the AXI4-Lite control interface and through the non-AXI error
output signals (si_r_error and si_w_error
), both of which remain sticky until the block is cleared.
Only problematic conditions observed on the SI of the firewall trigger faults. No conditions observed on the MI of the firewall trigger faults.
When configured for SI-side mode,
the AXI Firewall IP does not allow W-channel transfers to propagate
ahead of corresponding AW commands; any premature W-transfers are
stalled (s_axi_wready deasserted) until
the AW command is received.