The Unabridged Pentium 4 IA32 Processor Genealogy

The Snoop Result Signals are Shared, DEFER# Isn't

There are three snoop result signals (divided into two groups) that are sampled by the Request Agent during the Snoop Phase:

• HIT# and HITM# are the signals used by the Snoop Agents (i.e., the processor caches) to deliver the cache snoop result, or to stall the completion of the Snoop Phase if one or more of the Snoop Agents isn't ready to deliver the snoop result (see “Line Containing a Semaphore Is in the E or M State” on page 1185 for an example of snoop stall). Both HIT# and HITM# might be driven by multiple snoopers if any of them need to stall the completion of the Snoop Phase until the snoop result is available. At that time, each of the snoopers that have been stalling would stop driving ...