Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
Table 5-28 Root System Description Pointer Structure
Field
Byte
Length
Byte
Offset
Description
Signature 8 0 “RSD PTR ” (Notice that this signature must contain a trailing blank
character.)
Checksum 1 8 This is the checksum of the fields defined in the ACPI 1.0
specification. This includes only the first 20 bytes of this table, bytes
0 to 19, including the checksum field. These bytes must sum to
zero.
OEMID 6 9 An OEM-supplied string that identifies the OEM.
Revision 1 15 The revision of this structure. Larger revision numbers are backward
compatible to lower revision numbers. The ACPI version 1.0
revision number of this table is zero. The current value for this field
is 2.
RsdtAddress 4 16 32 bit physical address of the RSDT.
Length 4 20 The length of the table, in bytes, including the header, starting from
offset 0. This field is used to record the size of the entire table.
XsdtAddress 8 24 64 bit physical address of the XSDT.
Extended
Checksum
1 32 This is a checksum of the entire table, including both checksum
fields.
Reserved 3 33 Reserved field
5.2.6 System Description Table Header
All system description tables begin with the structure shown in Table 5-29. The Signature field
determines the content of the system description table. System description table signatures defined
by this specification are listed in Table 5-30.
Table 5-29 DESCRIPTION_HEADER Fields
Field
Byte
Length
Byte
Offset
Description
Signature 4 0 The ASCII string representation of the table identifier. Notice that if
OSPM finds a signature in a table that is not listed in Table 5-30,
OSPM ignores the entire table (it is not loaded into ACPI
namespace); OSPM ignores the table even though the values in the
Length and Checksum fields are correct.
Length 4 4 The length of the table, in bytes, including the header, starting from
offset 0. This field is used to record the size of the entire table.
Revision 1 8 The revision of the structure corresponding to the signature field for
this table. Larger revision numbers are backward compatible to
lower revision numbers with the same signature.
Checksum 1 9 The entire table, including the checksum field, must add to zero to
be considered valid.
OEMID 6 10 An OEM-supplied string that identifies the OEM.
110 April, 2015 Version 6.0