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Extensible Firmware Interface Specification
8-8 12/01/02 Version 1.10
Table 8-8. ACPI Device Path
Mnemonic
Byte
Offset
Byte
Length
Description
Type 0 1 Type 2 – ACPI Device Path.
Sub-Type 1 1 Sub-Type 1 ACPI Device Path.
Length 2 2 Length of this structure in bytes. Length is 12 bytes.
_HID 4 4
Device’s PnP hardware ID stored in a numeric 32-bit
compressed EISA-type ID. This value must match the
corresponding _HID in the ACPI name space.
_UID 8 4
Unique ID that is required by ACPI if two devices have the
same _HID. This value must also match the corresponding
_UID/_HID pair in the ACPI name space. Only the 32-bit
numeric value type of _UID is supported; thus strings must
not be used for the _UID in the ACPI name space.
Table 8-9. Expanded ACPI Device Path
Mnemonic
Byte
Offset
Byte
Length
Description
Type 0 1 Type 2 – ACPI Device Path.
Sub-Type 1 1 Sub-Type 2 Expanded ACPI Device Path.
Length 2 2 Length of this structure in bytes. Minimum length is
19 bytes. The actual size will depend on the size of
the _HIDSTR, _UIDSTR, and _CIDSTR fields.
_HID 4 4 Device’s PnP hardware ID stored in a numeric 32-bit
compressed EISA-type ID. This value must match the
corresponding _HID in the ACPI name space.
_UID 8 4 Unique ID that is required by ACPI if two devices have the
same _HID. This value must also match the corresponding
_UID/_HID pair in the ACPI name space.
_CID 12 4 Device’s compatible PnP hardware ID stored in a numeric
32-bit compressed EISA-type ID. This value must match at
least one of the compatible device IDs returned by the
corresponding _CID in the ACPI name space.
_HIDSTR 16 >=1 Device’s PnP hardware ID stored as a null-terminated ASCII
string. This value must match the corresponding _HID in
the ACPI name space. If the length of this string not
including the null-terminator is 0, then the _HID field is used.
If the length of this null-terminated string is greater than 0,
then this field supercedes the _HID field.
continued