Internal I/O Subsystem; Peripheral Component Interconnect Express (Pcie) Bus; Pcie Slots - IBM BladeCenter PS700 Technical Overview And Introduction

2.6 Internal I/O subsystem

Each POWER7 processor as implemented in the POWER7 processor-based blades utilizes a
single GX+ bus which is used to connect to the I/O subsystem. The I/O subsystem is a GX+
multifunctional host bridge chip which provides the following major interfaces:
One GX+ primary interface to the processor
Two 64-bit PCI-X 2.0 buses, one 64-bit PCI-X 1.0 bus, and one 32-bit PCI-X 1.0 bus
Four x8 PCI Express links
Two 10 Gbps Ethernet ports: Each port is individually configurable to function as two 1
Gbps ports
The PS702 with two POWER7 processors also has two GX+ multifunctional host bridge
chips. Unless otherwise noted, references to slots, embedded controllers and so forth are
assumed to be doubled for the PS702.
Note: Table 2-2 on page 45 indicates there are two GX+ buses in the POWER7 processor
however only one of them is active in the PS700 and PS701, and each processor in the
PS702.

2.6.1 Peripheral Component Interconnect Express (PCIe) bus

PCIe uses a serial interface and allows for point-to-point interconnections between devices
using a directly wired interface between these connection points. A single PCIe serial link is a
dual-simplex connection using two pairs of wires, one pair for transmit and one pair for
receive, and can only transmit one bit per cycle. It can transmit at the extremely high speed of
2.5 Gbps, which equates to a burst mode of 320 MBps on a single connection. These two
pairs of wires is called a lane. A PCIe link might be comprised of multiple lanes. In such
configurations, the connection is labeled as x1, x2, x8, x12, x16, or x32, where the number is
the number of lanes.
The PCIe expansion card options for the PS700, PS701, and PS702 blades support
Extended Error Handling (EEH). The card ports are routed through the BladeCenter
mid-plane to predetermined I/O switch bays. The switches installed in these switch bays must
match the type of expansion card installed, Ethernet, Fibre Channel, and so forth.

2.6.2 PCIe slots

The two PCIe slots are connected to the four x8 PCIe links on the GX+ multifunctional host
bridge chip. One of the links supports the CIOv connector and the other three links support
the CFFh connector on the blade. All PCIe slots are Enhanced Error Handling (EEH). PCI
EEH-enabled adapters respond to a special data packet generated from the affected PCIe
slot hardware by calling system firmware, which examines the affected bus, allows the device
driver to reset it, and continues without a system reboot. For Linux, EEH support extends to
the majority of frequently used devices, although various third-party PCI devices might not
provide native EEH support.
Expansion card form factors
There are two PCIe card form factors supported on the PS700, PS701, and PS702 blades:
CIOv
CFFh
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IBM BladeCenter PS700, PS701, and PS702 Technical Overview and Introduction