Advanced Configuration and Power Interface Specification

Device Configuration
Offset Field Name Definition
Byte 3 Resource Type Indicates which type of resource this descriptor describes. Defined
values are:
0 Memory range
1 I/O range
2 Bus number range
3–191 Reserved
192-255 Hardware Vendor Defined
Byte 4 General Flags Flags that are common to all resource types:
Bits [7:4] Reserved (must be 0)
Bit [3] Max Address Fixed, _MAF:
1 The specified maximum address is fixed
0 The specified maximum address is not fixed
and can be changed
Bit [2] Min Address Fixed,_MIF:
1 The specified minimum address is fixed
0 The specified minimum address is not fixed
and can be changed
Bit [1] Decode Type, _DEC:
1 This bridge subtractively decodes this address
(top level bridges only)
0 This bridge positively decodes this address
Bit [0] Ignored
Byte 5 Type Specific Flags Flags that are specific to each resource type. The meaning of the
flags in this field depends on the value of the Resource Type field
(see above).
Byte 6
Byte 7
Byte 8
Byte 9
Byte 10
Byte 11
Byte 12
Address space
granularity, _GRA bits[7:0]
Address space
granularity, _GRA
bits[15:8]
Address space
granularity, _GRA
bits[23:16]
Address space
granularity, _GRA
bits[31:24]
Address space
granularity, _GRA
bits[39:32]
Address space
granularity, _GRA
bits[47:40]
Address space
granularity, _GRA
bits[55:48]
A set bit in this mask means that this bit is decoded. All bits less
significant than the most significant set bit must be set. That is, the
value of the full Address Space Granularity field (all 64 bits) must
be a number (2 n -1).
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