Specifications

QSSC-S4R Technical Product Specification BIOS Initialization
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may vary from boot to boot with varying presence of PCI devices with PCI-PCI bridges. If a bridge device with a single
bus behind it is inserted into a PCI bus, all subsequent PCI bus numbers below the current bus are increased by one.
The bus assignments occur once, early in the BIOS boot process, and never change during the pre-boot phase.
16.3.2 Resource Assignment
The BIOS resource manager assigns the PIC-mode interrupt for the devices that are accessed by the legacy code.
The BIOS ensures that the PCI BAR registers and the command registers for all devices are correctly set up to match
the behavior of the legacy BIOS after booting to a legacy OS. Legacy code cannot make any assumption about the
scan order of devices or the order in which resources are allocated to them.
16.3.3 Automatic IRQ Assignment
The BIOS automatically assigns IRQs to devices in the system for legacy compatibility. A method is not provided to
manually configure the IRQs for devices.
16.3.4 EFI Optimized Boot support and Legacy Option ROMs
The BIOS has implemented a new Legacy Boot protocol. This protocol may or may not be installed depending on the
state of a new setup option called EFI Optimized Boot. If EFI Optimized Boot is disabled, an early DXE driver installs
the Legacy Boot Marker Protocol. Since EFI optimized boot does not load the CSM, video option ROM and INT
services are not loaded. However, EFI optimized boot does load an EFI video driver providing legacy-free video on the
local console via the on-board video controller. If the OS does not support the native EFI mode, then the system halts
with a blank screen after POST.
Note: SATA SW RAID and EFI Optimized Boot are mutually exclusive options. SATA SW RAID can boot only in Legacy Boot
mode. For more information on the two setup options, see Section 0 and Section 17.2.3.3.4.
16.3.5 EFI PCI APIs
The BIOS provides standard PCI protocols as described in the Extensible Firmware Interface Reference Specification,
Version 1.1.
16.3.6 Legacy PCI APIs
In the legacy mode, the system BIOS supports the INT 1Ah, AH = B1h functions as defined in the PCI BIOS
Specification
, Revision 2.1. The system BIOS supports the real mode interface.
16.3.7 Dual Video
The BIOS supports single and dual video modes on some server board models. By default, the dual video mode is
disabled.
x In the single video mode, the on-board video controller is disabled when an add-in video card is detected.
x In the dual video mode, the on-board video controller is enabled and is the primary video device. The external
video card is allocated resources and is considered the secondary video device.
16.4 PnP ISA
Although the platform does not support add-in ISA devices, some on-board devices require ISA resources. For on-
board ISA devices, the BIOS assigns I/O, memory, direct memory access (DMA) channels, and IRQs from the system
resource pool to the embedded PnP Super I/O device.
16.5 Keyboard / Mouse
The BIOS supports only USB keyboards and mice.
The system can boot without a keyboard or mouse attached. If present, the BIOS detects the keyboard during POST
and displays the message “Keyboard Detected” on the POST Screen.
16.6 Universal Serial Bus (USB)
On systems that use the Intel
®
Boxboro-EX Chipset chipset systems, on-board USB is provided
by the dual EHCI
controllers in the Intel
®
82801Jx I/O Controller Hub (ICH10).