
5-13
BUS TRANSACTIONS AND OPERATIONS
Phase of the Deferred Reply (the Snoop Result Phase indicates all changes in the length of data
returned).
The deferring agent may assert DEFER# in the Snoop Result Phase of the Deferred Reply to
retry the original transaction.
A Deferred Reply may receive any response except a Deferred Response. The response must fol-
low the protocol illustrated in Chapter 4, Bus Protocol. If a Retry Response is received, then the
addressed agent will retry the original transaction.
5.2.4.2.
ADDRESSED AGENT RESPONSIBILITIES (ORIGINAL REQUESTOR)
The addressed agent is the agent which issued the original transaction. It must decode the
DID[7:0]# returned on Aa[23:16]# and match it with a previously deferred transaction. At the
Snoop Result Phase of the Deferred Reply, the original requestor’s transaction is in the exact
same state as the Snoop Result phase for a non-deferred transaction (with DEN# assumed deas-
serted). HIT#/HITM#/DEFER# are used as in the original transaction. It must accept any re-
turned data and complete the original transaction as if it were not deferred. It must make the
appropriate snoop state transition at the Snoop Result Phase of the Deferred Reply, and must re-
issue the original transaction if a Retry Response is received.
5.2.5.
Reserved Transactions
These transaction encodings are reserved. No agent should take any action when they are seen.
They should be completely ignored.
5.3.
BUS OPERATIONS
This section describes bus operations. A bus operation is a bus procedure that appears atomic to
software even though it might not appear atomic on the bus. The operations discussed in this sec-
tion are those that have multiple transactions (such as locked operations) or those that have po-
tential multiple data transfers (implicit writebacks).
5.3.1.
Implicit Writeback Response
In response to any memory transaction, each caching agent issues an internal snoop operation.
If the snoop finds the accessed line in the Modified state in a writeback cache, then the caching
agent asserts HITM# in the Snoop Phase. The caching agent that asserted HITM# writes back
the Modified line from its cache during snoop-initiated Data Phase. This data transfer is called
REQa[4:0]#
0
0
0
0
1
1
1
0
0
x
Содержание Pentium Pro Family
Страница 17: ...1 Component Introduction ...
Страница 26: ...2 Pentium Pro Processor Architecture Overview ...
Страница 27: ......
Страница 36: ...3 Bus Overview ...
Страница 62: ...4 Bus Protocol ...
Страница 105: ...5 Bus Transactions and Operations ...
Страница 126: ...6 Range Registers ...
Страница 131: ...7 Cache Protocol ...
Страница 135: ...8 Data Integrity ...
Страница 148: ...9 Configuration ...
Страница 161: ...10 Pentium Pro Processor Test Access Port TAP ...
Страница 172: ...11 Electrical Specifications ...
Страница 201: ...12 GTL Interface Specification ...
Страница 229: ...13 3 3V Tolerant Signal Quality Specifications ...
Страница 233: ...14 Thermal Specifications ...
Страница 239: ...15 Mechanical Specifications ...
Страница 241: ...15 2 MECHANICAL SPECIFICATIONS s Figure 15 1 Package Dimensions Bottom View ...
Страница 252: ...16 Tools ...
Страница 260: ...16 8 TOOLS Figure 16 4 Generic MP System Layout for Debug Port Connection ...
Страница 264: ...17 OverDrive Processor Socket Specification ...
Страница 290: ...A Signals Reference ...
Страница 320: ...Index ...
Страница 328: ......