
5-12
BUS TRANSACTIONS AND OPERATIONS
The SMI Acknowledge Transaction can be observed by the bridge agents to determine when an
agent enters or exits SMM mode.
5.2.4.
Deferred Reply Transaction
An agent issues a Deferred Reply Transaction to complete an earlier transaction for which the
response was deferred. The Deferred Reply Transaction may return data to complete an earlier
Memory Read, I/O Read, or Interrupt Acknowledge Transaction, or it may simply indicate the
completion of an earlier Memory Write, I/O Write, or Invalidate Transaction (note that the data
transfer for a memory write or I/O write takes place in the data phase of the earlier transaction).
After being deferred, the Invalidate Transaction may have hit a modified line on another bus,
which will cause the Deferred Reply Transaction to return data.
The deferring agent is both the requesting agent and the responding agent for the Deferred Reply
Transaction. The addressed agent is the agent which issued the original transaction.
5.2.4.1.
REQUEST INITIATOR RESPONSIBILITIES (DEFERRING AGENT)
This transaction uses the address bus to return the Deferred ID, which was sent with the original
request on DID[7:0]#. The Deferred ID is returned on address Aa[23:16]# signals. The deferring
agent will not place a unique ID onto Ab[23:16]#, since DEN# is deasserted.
See Section 5.3.3., “Deferred Operations” for Deferred ID generation.
The ownership transfer of a cache line transferred from the deferring agent to the original re-
questing agent takes place during Snoop Result Phase of this transaction. Since this transaction
is not snooped, HIT# and HITM# signals are used by the requesting agent. For a Deferred Reply
resulting from a Memory Read Data Line Transaction, the deferring agent must assert HIT# in
the deferred reply’s Snoop Result Phase if the original requesting agent should place the line in
the Shared state. If the original requester does not observe HIT# active, it may place the line in
Exclusive state. For a Deferred Reply resulting from a Memory Invalidate Transaction which hit
a modified line on another bus, the deferring agent must echo the HITM# in the Snoop Result
REQa[4:0]#
REQb[4:0]#
0
0
0
0
0
x
x
x
x
x
Ab[15:8]#
Ab[7:3]#
xx
x
SPLCK#=0
rsvd
DEN#=0
rsvd
Aa[23:16]#
Ab[23:16]#
DID[7:0]# (original)
xx
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: ......