Operating System Boot, Sleep, And Wake; Advanced Configuration And Power Interface (Acpi) - Intel SE7520AF2 Technical Product Specification

System BIOS
based on the intended usage for that system. For example, a server system that will be used in
small home/office environments has different requirements than the one used for enterprise
applications.
The Intel® Server Board SE7520AF2 supports Microsoft Hardware Design Guide 3.0.
5.17.2

Advanced Configuration and Power Interface (ACPI)

The Intel® SE7520AF2 BIOS is ACPI-compliant. The primary role of the BIOS is to provide
ACPI tables. The POST creates the ACPI tables and locates them in extended memory (above
1MB). The location of these tables is conveyed to the ACPI-aware operating system 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 operating system, 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 operating system 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, issues the appropriate
command to the mBMC/BMC to enable ACPI mode 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.
ACPI has three runtime components:
− ACPI Tables: These tables describe the interfaces to the hardware. ACPI tables can
make use of a p-code type of language, the interpretation of which is performed by the
operating system. The operating system contains and uses an ACPI Machine Language
(AML) interpreter that executes procedures encoded in AML and stored in the ACPI
tables. AML is a compact, tokenized, abstract machine language. The tables contain
information about power management capabilities of the system, APICs, bus structure.
The tables also describe control methods that operating system uses to change PCI
interrupt routing, control legacy devices in Super I/O, and find out the cause of the wake
event, and handle PCI hot plug if applicable.
− ACPI Registers: The constrained part of the hardware interface, described (at least in
location) by the ACPI tables.
− ACPI BIOS: This is the code that boots the machine and implements interfaces for
sleep, wake, and some restart operations. The ACPI Description Tables are also
provided by the ACPI BIOS.
All IA32 server platforms support S0, S4, and S5 states. In addition to these, the Intel® Server
Board SE7520AF2 also supports the S1 state. S1 and S4 are considered sleep states. The
ACPI specification defines the sleep states and requires the system to support at least one of
them.
While entering the S4 state, the operating system saves the context to the disk and most of the
system is powered off. The system can wake on a power button press, or a signal received from
a wake-on-LAN compliant LAN card (or on-board LAN), modem ring, PCI power management
interrupt, or RTC alarm. The BIOS performs complete POST upon wake up from S4, and
initializes the platform.
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Intel order number C77866-003
Intel® Server Board SE7520AF2 TPS
Revision 1.2