1. A method, comprising: communicating between at least first and second devices over a bus in accordance with a bus address space, including providing direct access over the bus to a local address space of the first device by mapping at least some of the addresses of the local address space to the bus address space; in response to detecting, by the first device or the second device, that the second device requires to access a local address in the local address space that is not currently mapped to the bus address space, mapping the local address to the bus address space; and accessing the local address directly, by the second device, using the mapping.