31:27

0h

RO

Reserved (RSVD_​M)

Reserved

26:24

0h

RW/O

FPB MEM High Vector Size Supported (FPBMEMHVECSIZES)

Indicates the size of the FPB MEM High Vector implemented in hardware.



Defined encodings are:

000b 256 bits

001b 512 bits

010b 1 K bits

011b 2 K bits

100b 4 K bits

101b 8 K bits



All other encodings are Reserved.



All defined Granularities are allowed for all defined vector sizes.



If the FPB MEM High Decode Mechanism Supported bit is Clear, then the value in this field is undefined and must be ignored by software.

23:19

0h

RO

Reserved

18:16

0h

RW/O

FPB MEM Low Vector Size Supported (FPBMEMLVECSIZES)

Indicates the size of the FPB MEM Low Vector implemented in hardware, and constrains the allowed values software is permitted to write to the FPB MEM Low Vector Start field.



Defined encodings are:



Value : Size : Allowed Granularities in RID units

----------------------------------------------------------------

000b : 256 bits : 1, 2, 4, 8, 16

001b : 512 bits : 1, 2, 4, 8

010b : 1 K bits : 1, 2, 4

011b : 2 K bits : 1, 2

100b : 4 K bits : 1



All other encodings are Reserved.



If the FPB MEM Low Decode Mechanism Supported bit is Clear, then the value in this field is undefined and must be ignored by software

15:11

0h

RO

Reserved

10:8

0h

RW/O

FPB RID Vector Size Supported (FPBRIDVECSIZES)

Indicates the size of the FPB RID Vector implemented in hardware, and constrains the allowed values software is permitted to write to the FPB RID Vector Granularity field.



Defined encodings are:

Value : Size : Allowed Granularities in RID units

----------------------------------------------------------------

000b : 256 bits : 8, 64, 256

010b : 1 K bits : 8, 64

101b : 8 K bits : 8



All other encodings are Reserved.



If the FPB RID Decode Mechanism Supported bit is Clear, then the value in this field is undefined and must

be ignored by software.

7:3

0h

RO

FPB Num Sec Dev (FPBNSECDEV)

For Upstream Ports of Switchesonly, this field indicates the quantity of Device Numbersassociated with the Secondary Side of the UpstreamPort bridge. The quantity is determined by adding oneto the numerical value of this field.Although it is recommended that Switch implementationsassign Downstream Ports using all 8 allowed Functionsper allocated Device Number, such that all DownstreamPorts are assigned within a contiguous range of Deviceand Function Numbers, it is, however, explicitlypermitted to assign Downstream Ports to FunctionNumbers that are not contiguous within the indicatedrange of Device Numbers, and system software isrequired to scan for Switch Downstream Ports at everyFunction Number within the indicated quantity of DeviceNumbers associated with the Secondary Side of theUpstream Port.



This field is Reserved for Downstream Ports

2

0h

RW/O

FPB MEM High Decode Mechanism Supported (FPBMEMHS)

If set, indicates that the FPB MEM High Vector mechanism is supported

1

0h

RW/O

FPB MEM Low Decode Mechanism Supported (FPBMEMLS)

If set, indicates that the FPB MEM Low Vector mechanism is supported

0

0h

RW/O

FPB RID Decode Mechanism Supported (FPBRIDS)

If set, indicates that the FPB RID Vector mechanism is supported