In the MESI protocol, what state does a cache line transition to if it is in the 'E' (Exclusive) state and another cache attempts to read the same data?
The 'E' state means the local cache has the only copy, and it is clean (consistent with main memory). When a second cache performs a read request, the local cache's status of exclusivity is broken. The local cache supplies the data to the requesting cache (and potentially snoops the bus to see the data being supplied from another source/memory), and both caches now hold a clean, identical copy. The original cache transitions from 'E' to 'S' (Shared), and the new cache enters the 'S' state.
