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System BIOS
the BIOS initializes and configures the root hub ports and looks for a keyboard, mouse, boot
device, and the USB hub and enables them.
The BIOS implements legacy USB keyboard support. USB legacy support in BIOS translates
commands that are coming from USB KB/Mouse and translates it into the format the PS2 device
generated then sent to the KB controller to emulate the PS2 behavior. It makes the USB
keystrokes and the USB mouse movements appear as if they originated from the standard PS/2
devices.
Emulation is transparent to the software. Legacy support is required if the system does not
contain a PS/2 keyboard and mouse. BIOS support is not meant to replace a USB driver but will
enable the system to allow the USB driver to control these devices.
The PS/2 keyboard/mouse port is considered the primary connection for these input devices.
USB ports are treated as a contingency. Use of legacy USB emulation is not encouraged,
because USB legacy support involves many SMI (System Management Interrupt)s and slows the
POST and OS loader.
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USB legacy support involves many SMIs and slows the POST and operating system
loader.
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It is possible to breach system security with a USB keyboard and mouse. Security
features are covered in Section 6.6.
In addition, BIOS also support USB Floppy/CDROM/HD boot. With this functionality, system can
work without the legacy device support to achieve legacy-free requirement.
6.3
BIOS Supported Server Management Features
The SE7500CW2 server BIOS supports many standards-based server management features
and several proprietary features.
This section describes the implementation of the standard and the proprietary features including
console redirection, The BIOS owns console redirection over a serial port.
6.3.1
Advanced Configuration and Power Interface (ACPI)
The primary role of the ACPI BIOS is to supply the ACPI Tables. POST creates the ACPI tables
and locates them above 1 MB in extended memory. The location of these tables is conveyed to
the ACPI-aware OS through a series of tables located throughout memory. The format and
location of these tables is documented in the publicly available ACPI specification. To prevent
conflicts with a non-ACPI-aware OS, the memory used for the ACPI tables is marked as
"reserved" in the INT 15h, function E820h.
As described in the ACPI specification, an ACPI-aware OS generates an SMI to request that the
system be switched into ACPI mode. The BIOS responds by setting up all system (chipset)
specific configuration required to support ACPI and sets the SCI_EN bit as defined by the ACPI
specification. The system automatically returns to legacy mode on hard reset or power-on reset.
There are three runtime components to ACPI:
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Revision 1.40
SE7500CW2 Server Board Technical Product Specification
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