1. An apparatus for use in a processor for controlling access of a plurality of processor clients to a plurality of memory instances of an internal memory of the processor, the apparatus comprising: an internal memory controller comprising a configurable switching element; the configurable switching element being connectable between the plurality of clients and the plurality of memory instances and being operative to control access of particular ones of the plurality of clients to particular ones of the plurality of memory instances; wherein the configurable switching element is configurable to connect any one of at least a subset of the plurality of clients to each of at least a subset of the plurality of memory instances, such that in a first selectable configuration of the configurable switching element, a given one of the processor clients is permitted to access a first set of memory instances comprising one or more of the plurality of memory instances, and in a second selectable configuration of the configurable switching element, the given processor client is permitted to access a second set of memory instances comprising one or more of the plurality of memory instances, the second set being different than the first set.