Datasheet

Intel
®
Xeon
®
Processor C5500/C3500 Series
February 2010 Datasheet, Volume 1
Order Number: 323103-001 115
Interfaces
2.5.5.3.1 APIC ID Decode
APIC ID decode is used to determine the Target NodeID for non-broadcast interrupts.
Three bits of the APIC ID is used to select from eight targets. Selection of the APIC ID
bits is dependent on the processor, so modes exist within the APIC ID decode register
to select the appropriate bits. The bits that are used is also dependent on the type of
interrupt (physical or extend logical).
2.5.5.3.2 Subtractive Decode
Requests that are subtractively decoded are sent to the legacy DMI port. When the
legacy DMI port is located on a remote IIO over Intel
®
QPI this decoder simply
specifies the NodeID of the peer legacy IIO that is targeted. If this decoder is disabled,
then legacy DMI is not available over Intel
®
QPI, and any subtractive decoded request
that is received by the Intel
®
QPI cluster results in an error.
2.5.5.3.3 DCA Tag
DCA enabled writes result in a PrefetchHint message on Intel
®
QPI that is sent to a
caching agent on Intel
®
QPI. The NodeID of the caching agent is determined by the PCI
Express tag. The IIO supports a number of modes for which tag bits correspond to
which NodeID bits. The tag bits may also translate to cache target information in the
packet.
2.5.6 Special Response Status
Intel
®
QPI includes two response types: normal and failed. Normal is the default. Failed
is discussed in this section.
On receiving a failed response status the IIO continues to process the request in the
standard manner, but the failed status is forwarded with the completion. This response
status is also logged as an error.
The IIO sends a failed response to Intel
®
QPI for some failed response types from PCI
Express.
2.5.7 Illegal Completion/Response/Request
IIO explicitly checks all transaction for compliance to the request-response. If an illegal
response is detected it is logged and the illegal packet is dropped.
Table 65. I/O Decoder Entries
Field Type
Address
Base/Range
Size
(Bytes)
attr Interleave CSR Register Comments
VGA/CSeg Memory 000A_0000 128K MMIO None QPIPVSAD
Space can be
disabled.
LocalxAPIC Memory FEE0_0000 1M IPI
8 deep
table
QPIPAPICSAD
Which bits of address
select the table entry
is variable.
Special
Requests
Targeting
DMI.
Memory N/A N/A Varies None QPIPSUBSAD
Peer-to-peer between
PCie and DMI is not
supported.
DCA Tag NodeID 0 64 NodeID
Direct
Mapping
QPIPDCASAD
Direct mapping
modes for tag to
NodeID.