SELECTIVE SMART DISCARDS WITH PREFETCHABLE AND CONTROLLED-PREFETCHABLE ADDRESS SPACE

A bridging device has a first port to allow the device to communicate with other devices on an expansion bus and a second port to allow the device to communicate with devices on a second bus. The device also includes a memory to store data and a processor or logic to prefetch data upon request from a device on the expansion bus, tag any remaining prefetched data with an identifier upon a disconnecting event, and retain the prefetched data until a discarding event occurs. A method of controlling prefetch transactions on an expansion bus involves prefetching data across a primary bus for a device on a secondary bus. An indication that a disconnecting event has occurred is detected and any remaining prefetched data remaining is tagged with an identifier and retained. The data may be prefetched from a controlled prefetch region in the memory.