When an AXI transaction is received, the master ID (MID) that is available as part of AxUSER is compared against all entries of the MID list, together with parity checks (if enabled).
An AXI MID matches the nth entry if the following is true.
(MASTER_IDnn.MASTER_ID_MASK & MID ==MASTER_IDnn.MASTER_ID_MASK & MASTER_IDnn.MASTER_ID) && (~CTRL.MID_PARITY_EN || CTRL.MID_PARITY_EN & (MASTER_IDnn.MASTER_ID_PARITY == Computed parity))
An entry in the master ID list consists of the fields shown in Table: Master ID List Entry.
For a matched entry, if it is enabled by the corresponding bit of the PERMISSIONS field (as defined by the PERM field shown in Table: Aperture Permissions Register Format) and if the read only (MASTER_IDnn.MIDR) bit is set, only read transactions are allowed and write transactions are not allowed.
The bitwise result of matching against each entry of the master ID list is stored in the match vector (MATCH [m–1:0]. The parity bit is computed and written by the software if the parity option is enabled.