Intel Xeon User Manual

Intel
®
82870P2 (P64H2)
112 Design Guide
8.2.7 Three or More Slot Serial Mode
Serial Mode allows for three to six slots to be hot pluggable. This mode can also be used to enable
slots that are hot pluggable, and others that are not on the same PCI/PCI-X bus.
8.2.7.1 Hot Plug and Non-Hot Plug Combinations
To accomplish hot plug and non-hot plug combinations, put the non-hot pluggable devices on their
own hot plug serialization logic (for M66EN and PCIXCAP), and scan them in for software to
view. Don’t electrically isolate those devices—allow software to see their capabilities to choose
bus frequency properly.
8.2.7.2 Required Additional Logic
Serial Mode requires a power switch to be used to turn the slot power on and off on all Hot
Pluggable slots. Serial Mode also requires the use of a bus and clock switch. In addition, Serial
Mode requires auto bus and clock disable logic to immediately disable the PCI bus and clock when
the power fault signal (from the power switch) goes active.
If the platform supports PME# or SMBus connections to the slots, isolation logic is required to
disconnect these signals before inserting or removing a card. See the PCI Hot Plug Specification,
Revision 1.1 for implementation details.
8.2.7.3 Debounced Hot Plug Switch Input
The switch inputs to the serialization/deserialization logic may require debouncing logic. This
depends upon the logic used for serialization, and is left up to the individual designer.
8.2.7.4 Comparator Circuit for PCIXCAP1/PCIXCAP2 Pins
A comparator circuit is required for properly decoding the PCI/PCI-X capability of the slot. Refer
to the PCI Local Bus Specification, Revision 2.2 for this circuit. An example of this circuit is also
contained in the reference schematics.
8.2.7.5 HPxSLOT [2:0]
The HPxSLOT [2:0] pins are pull-ups/pull-downs that are used to determine the slot count and
mode of operation for the P64H2 Hot Plug Controller. These pins should be strapped to the proper
slot count value. See Table 8-8.
8.2.7.6 Stutter Logic for Implementing Fewer Than Six Slots
The serialized input/output data stream effectively stutters around the unused bit positions
corresponding with the number of Hot Plug slots determined by HPx_SLOT[2:0]. This reduces the
amount of logic required to implement fewer than six slots. If HPx_SLOT[2:0] is strapped to
enable four Hot Pluggable slots, bit positions 4 and 5 would be skipped. Refer to Figure 8-15 for an
example of this. Note that this concept also applies to the output data stream as well.

Intel Xeon Specifications

General

Brand	Intel
Model	Xeon
Category	Processor
Language	English