Specifications

QSSC-S4R Technical Product Specification BIOS Role in Server Management
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20.5 System Management BIOS (SMBIOS)
The BIOS provides support for the System Management BIOS Reference Specification, Version 2.5, to create a
standardized interface for manageable attributes that are expected to be supported by DMI-enabled computer systems.
The BIOS provides this interface via data structures through which the system attributes are reported. Using SMBIOS,
a system administrator can obtain the types, capabilities, operational status, installation date and other information
about the server components.
This section defines the structures supported in this product. Where specific information is entered in a structure, a
table is provided to define that information. All other field information is filled according to the System Management
BIOS Reference Specification.
20.5.1 Access Methods
As defined in the SMBIOS specification, the approved method of accessing the SMBIOS information is through the
table method. The table convention allows the SMBIOS structures to be accessed under 32-bit protected-mode
operating systems.
The total number of structures can be obtained from the SMBIOS entry-point structure. The system information is
presented to an application as a set of structures that are obtained by traversing the SMBIOS structure table
referenced by the SMBIOS entry-point structure.
20.5.1.1 Structure Table Entry Point
The SMBIOS entry point structure can be located by the application software by searching for the structure information
in the following table within the physical memory address range of 000F0000h to 000FFFFFh.
EFI-aware operating systems and applications can locate the SMBIOS table using the standard EFI system table
mechanism. The SMBIOS tables are located above physical address 100000h.
Table 148. SMBIOS Table Structure for Locating SMBIOS Tables
Of
f
set Name Length Value Description
00h
A
nchor String Four
bytes
“_SM_” 4 ASCII characters to mark the beginning of the entry point.
04h Entry Point Structure
Checksum
Byte Varies Checksum of whole structure.
05h Entry Point Length Byte 1Fh Number of bytes in this table.
06h SMBIOS Major
Revision
Byte 02h The major revision of the SMBIOS specification that this
system is following:
02 for rev 2.5.
07h SMBIOS Minor
Revision
Byte 05h The minor revision of the SMBIOS specification that this
system is following:
05 for 2.5.
08h Maximum Structure
Size
Word Varies Size of largest supported structure.
0Ah Entry Point Revision Byte 00h 00 indicate compliance with entry point defined in SMBIOS
2.1 spec, which has not changed since the 2.1 spec.
0Bh Formatted Area Five bytes 0000000000h Reserved and set to all 00h.
10h Intermediate Anchor
String
Five bytes “_DMI_” 5 ASCII characters paragraph aligned, for legacy DMI
browsers.
15h Intermediate
Checksum
Byte Varies Checksum from 10h to end of structure.
16h Structure Word Varies Total length in bytes of structure pointed at
Table Length by offset 18h.
18h Structure Table
A
ddress
DWord Varies 32-bit physical starting address of the SMBIOS structure
table.
1Ch Number of SMBIOS
Structures
Word Varies Total number of SMBIOS structures present.
1Eh SMBIOS BCD
Revision
Byte 25h Bits 7:4 - Major revision
Bits 3:0 - Minor revision
20.5.2 SMBIOS Structures Supported
This System BIOS supports the structure types listed in the following sections.