Advanced Configuration and Power Interface Specification

Device Configuration
Offset
Byte 11
Field Name, ASL Field
Name
Range length, _LEN,
bits[15:8]
Definition
This field contains the upper eight bits of the memory range length.
The range length field provides the length of the memory range in
256 byte blocks.
Note: Address bits [7:0] of memory base addresses are assumed to be 0.
Note: A Memory range descriptor can be used to describe a fixed memory address by setting the range
minimum base address and the range maximum base address to the same value.
Note: 24-bit Memory Range descriptors are used for legacy devices.
Note: Mixing of 24-bit and 32-bit memory descriptors on the same device is not allowed.
See Section 19.6.79, “Memory24 (Memory Resource Descriptor Macro),” for a description of the
ASL macro that creates a 24-bit Memory descriptor.
6.4.3.2 Vendor-Defined Descriptor
Type 1, Large Item Name 0x4
The vendor defined resource data type is for vendor use.
Table 6-205 Large Vendor-Defined Resource Descriptor Definition
Offset Field Name Definition
Byte 0 Vendor Defined Descriptor Value = 0x84 (10000100B) – Type = 1, Large item name
= 0x04
Byte 1 Length, bits [7:0] Lower eight bits of data length (UUID and vendor data)
Byte 2 Length, bits [15:8] Upper eight bits of data length (UUID and vendor data)
Byte 3 UUID specific descriptor sub type UUID specific descriptor sub type value
Byte 4-19 UUID UUID Value
Byte 20-
(Length+20)
Vendor Defined Data
Vendor defined data bytes
ACPI 3.0 defines the UUID specific descriptor subtype field and the UUID field to address potential
collision of the use of this descriptor. It is strongly recommended that all newly defined vendor
descriptors use these fields prior to Vendor Defined Data.
See VendorLong (page 900) for a description of the ASL macro that creates a long vendor-defined
resource descriptor.
6.4.3.3 32-Bit Memory Range Descriptor
Type 1, Large Item Name 0x5
This memory range descriptor describes a device’s memory resources within a 32-bit address space.
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