A stream ID is used to map the incoming transaction to a context by using the stream mapping table. The characteristics of the stream ID are as follows:
The width of the stream ID is selected during the MMU-500 configuration.
You must specify the stream ID on a dedicated AXI sideband signal. Select the
Stream ID - width of the sideband signal parametervalue from the range 1-10 bits, and dedicated sideband signals are used for read and write transactions.
For more information about streamID signals, see Sideband signals.
The stream ID width in the TCU is a constant 15-bits. The stream ID from each TBU is zero-extended to form a 10-bit field appended to a 5-bit TBU ID field, making it 15-bits wide. This arrangement ensures that the stream ID presented to each TBU must not be unique, and happens at the TCU. If the Stream ID presented to each TBU is already unique, and the TBU ID addition is not required, then you must ensure that the TBU ID field is masked in the SMR.
See the ARM® System Memory Management Unit Architecture Specification for more information on stream ID-to-context mapping.