Specifications

QSSC-S4R Technical Product Specification BIOS Initialization
171
HW Domain
User Domain OS Domain
Begin
User inserts device in
the HP-capable PCI
Express slot
User closes MRL
Hot-plug controller detects the
Attention Button event and
sends a notification to the PCI
Express Root Port
The Root Port updates
Slot Status states and
triggers a platform hot-
plug event depending
on the Event
Generation configured
and OS type.
OS Hot-plug Driver
performs the
necessary
initialization, including
Power Control, and
Attention and Power
Indicators.
OS HP driver triggers
bus re-enumeration
OS HP driver
searches for and loads
device driver for the
hot-plugged device.
Event Generation:
MSI for Native Hot-
plug, or ACPI GPE for
BIOS-assisted Hot-
plug.
BIOS uses ACPI
method to determine
OS capability and
configure Hot-plug
handling and signaling
operations accordingly
User presses Attention
Button
Native Hot-plug
OS Domain
OS Hot-plug Driver
performs basic
initialization
OS HP driver invokes
ACPI ASL for BIOS-
assistance on hot-add
operations (Power
Control, and Attention
and Power Indicators)
OS HP driver triggers
bus re-enumeration
and loads the
appropriate device
driver for the hot-
plugged device
ACPI-assisted Hot-plug
Figure 76. PCIE hotplug flow chart
For more details, please refer to the
PCI Express Base Specification v.2.0. for more details.
16.8.1.1 PCI Express Bifurcation
QSSC-S4R platforms have a total of eleven PCI Express ports. But it employs only four hot plug controllers for PCI
Express. Hence only four x8 Gen2 PCI Express slots are hot plug
enabled on QSSC-S4R platforms.
Table 104. PCIe Bifurcation: hot-swap and non hot-swap configuration
# Silicon Type Purpose Length Hot-
Plug
1 IOH-1 Gen2 x8 8Gbps PCI Express x8 Slot 1 Yes
2 IOH-1 Gen2 x8 8Gbps PCI Express x8 Slot 2 Yes
3 IOH-1 Gen2 x8 8Gbps PCI Express x8 Slot 3 Half No
4 IOH-2 Gen2 x8 8Gbps PCI Express x8 Slot 4 Half No