Default values and modifiability of attributes
The master must set the value of every AMBA-PV extension attribute prior to passing the transaction object through an interface method call.
Table 2-1 Default values and modifiability of the AMBA-PV extension attributes
If an AMBA-PV extension object is re-used, the modifiability rules cease to apply at the end of the lifetime of the corresponding transaction instance. The rules re-apply if the AMBA-PV extension object is re-used for a new transaction.
After adding the AMBA-PV extension to a transaction object
and passing that transaction object as an argument to an interface
method call (
transport_dbg()), the master must not modify
any of the AMBA-PV extension attributes during the lifetime of the
An interconnect can modify the ID attribute, but only before
passing the corresponding transaction as an argument to an interface
method call (
transport_dbg()) on the forward path. When
the interconnect has passed a pointer to the AMBA-PV extension to
a downstream model, it is not permitted to modify the ID of that
extension object again during the entire lifetime of the corresponding
As a consequence of the above rule, the ID attribute is valid
immediately on entering any of the method calls
transport_dbg(). Following the return from
any of those calls, the ID attribute has the value set by the interconnect
The interconnect and slave can modify the response attribute
at any time between having first received the corresponding transaction
object and the time at which they pass a response upstream by returning
control from the
The master can assume it is seeing the value of the AMBA-PV extension response attribute only after it has received a response for the corresponding transaction.
If the AMBA-PV extension is used for the direct memory or debug transport interfaces, the modifiability rules given here must apply to the appropriate attributes of the AMBA-PV extension, namely the ID, privileged, non-secure, and instruction attributes.