AXI Transaction ID Filtering¶

In order to facilitate constraining the recovery core’s accessibility, the I3C core implements an AXI transaction ID filtering mechanism.

Transaction IDs are passed using the aruser and awuser signals.

The ID filtering logic is optional and depends on the AXI_ID_FILTERING macro definition.

Recovery core configuration includes a parameter denoting the NUM_PRIV_IDS - number of privileged IDs that are granted read and write access when the filtering mechanism is enabled.

Having AXI_ID_FILTERING defined requires NUM_PRIV_IDS to be greater than 0. This is verified with an assertion.

Undefined AXI_ID_FILTERING and non-zero NUM_PRIV_IDS are considered a legal configuration and causes the ID filtering logic to not be included in the design.

The filtering mechanism is controlled via:

• disable_axi_filtering_i recovery core port to disable the filtering mechanism

  • 1'b0 - enable AXI filtering

  • 1'b1 - disable AXI filtering

• [0:AXI_ID_WIDTH-1] priv_ids_i [0:NUM_PRIV_IDS-1] recovery core port containing privileged IDs

  • Each privileged ID should be of width AXI_ID_WIDTH passed at priv_ids_i[k] for each k in {0 … NUM_PRIV_IDS - 1}

  • All NUM_PRIV_IDS entries are expected to be set to valid privileged IDs

When the filtering is enabled, any transaction attempt outside of the privileged IDs will be met with a SLVERR (0b10) error on the respective AXI response channel.

The above-mentioned disable_axi_filtering_i and priv_ids_i ports will not be included in the design if AXI_ID_FILTERING is not defined.